Covalent modification of metal surfaces   

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent application Ser. No. 60/819,200, filed Jul. 7, 2006, the entirety of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

Modification of inorganic substrates with polymeric materials has been utilized in a range of applications across numerous scientific disciplines including analytical chemistry, biology, and electronics. (Mansky, P., et al. Science 1997, 275, 1458-1460; Huang, Z. Langmuir, 1997, 13, 6480-6484. Granick, S. et. al. J. Polym. Sci. B. 2003, 41, 2755-2793.) Inorganic substrates can be coated with polymers or other molecules using a number of currently available methods. One popular, simple method involves the physical adsorbtion of a polymer to a substrate through coating or other deposition techniques. Other methods utilize covalent or ionic bonding between functionality on a polymer, or small molecule, and functionality present on the substrate surface to achieve modification. (Denes, A. R. et. al. J. Appl. Polym. Sci. 2001, 81, 3425-3438). While simple adsorption of polymers to metal substrates has proven successful in many cases, this procedure does not produce mechanically robust coatings with long-term stability. Post-adsorption crosslinking (Dong, B. et. al.; J. Appl. Polym. Sci., 2005, 97, 485-497.) of the polymer coating may increase the toughness and short-term performance of the resulting film, but such crosslinking can also result in cracking and flaking of the polymer films over time, resulting in mechanical failure and a dramatic reduction in film properties. The chemical attachment of functional polymers to a metal substrate introduces a stable, robust linkage between polymer chains and the metal substrate and represents a more desirable scenario for many applications where the long-term stability of the coating is required for optimal performance. (Hara, H. et. al. Adv. Drug Del. Rev. 2006, 58, 377-388.) However, the methodologies to prepare covalent attachment of polymers to metallic and non-metallic substrates has thus far been limited to only a few examples of suitable substrates and complimentary chemical functionalities. Such examples include the near-covalent interaction between gold substrates and thiol-functionalized molecules, covalent bonds formed between silica and alcohol, silyl chloride, or silyl alcohol-functionalized compounds, and covalent bonds formed between hydrogen-functionalized silicon surfaces and alkene-substituted molecules. (Mansky, P., et. al. Science 1997, 275, 1458-1460, Pesek, J. J.; Matyska, M. T. Interface Science 1997, 5, 103-117.)

Accordingly, it would be advantageous to provide a method of modifying metal surfaces to provide a metal substrate capable of forming covalent bonds with appropriately functionalized polymers or small molecule derivatives.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a method for covalently modifying a metal surface via dehydration reaction.

FIG. 2 depicts a method for covalently modifying a metal surface via condensation reaction.

FIG. 3 depicts a method for covalently modifying a metal surface via dehydration reaction.

FIG. 4 depicts a method for covalently modifying a metal surface via condensation reaction.

FIG. 5 depicts a method for covalently modifying a metal surface via dehydration reaction.

FIG. 6 depicts a method for covalently modifying a metal surface via condensation reaction.

FIG. 7 depicts a method for covalently modifying a metal surface via dehydration reaction.

FIG. 8 depicts a method for covalently modifying a metal surface via condensation reaction.

FIG. 9 depicts a method for covalently modifying a metal surface and crosslinking via dehydration reaction.

FIG. 10 depicts a method for covalently modifying a metal surface via condensation reaction followed by crosslinking.

FIG. 11 depicts a method for PEGylating a metal surface via dehydration reaction.

FIG. 12 depicts a method for PEGylating a metal surface via condensation reaction.

DETAILED DESCRIPTION

The present invention provides methods for covalently modifying a metal surface with a polymeric group or a small molecule organic moiety. In order to covalently bond the polymeric group or small molecule organic moiety to the metal surface, the metal surface is treated to introduce hydroxyl groups. In certain embodiments, the present invention provides a method for covalently modifying a metal surface, comprising the steps of introducing hydroxyl groups onto a metal substrate and covalently bonding a polymer or small molecule organic moiety onto the resulting hydrophilic metal surface.

Compounds of this invention include those described generally above, and are further illustrated by the embodiments, sub-embodiments, and species disclosed herein. As used herein, the following definitions shall apply unless otherwise indicated. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75th Ed. Additionally, general principles of organic chemistry are described in “Organic Chemistry”, Thomas Sorrell, University Science Books, Sausalito: 1999, and “March\'s Advanced Organic Chemistry”, 5th Ed., Ed.: Smith, M. B. and March, J., John Wiley & Sons, New York: 2001, the entire contents of which are hereby incorporated by reference.

As used herein, the term “sequential polymerization”, and variations thereof, refers to the method where after a first monomer (e.g. NCA or lactam) is incorporated into the polymer, thus forming a “block”, a second monomer (e.g. NCA or lactam) is added to the reaction and the polymerization continues in a similar fashion resulting in the formation of multi-block copolymers.

As used herein, the term “block copolymer” refers to a polymer comprising two or more polymer portions. The term “multi-block copolymer” refers to a polymer comprising at least three separate polymer portions. These are also referred to as triblock copolymers, tetrablock copolymers, etc. Such multi-block copolymers may be of the format X-W-X′, W-X-X′, W-X-X′-X″ or X′-X-W-X-X′, wherein W is a certain synthetic polymer portion and X, X′, and X″ are differing polymer chains. In certain aspects, the synthetic polymer is used as the center block which allows the growth of multiple blocks symmetrically from center.

As used herein, the term “synthetic polymer” refers to a polymer that is well known in the art and includes polystryrene, polyalkylene oxides, polyacrylates, polyacrylamides, polyamines, polyolefins, and derivatives thereof.

As used herein, the term “natural polymer” refers to a polymer that is well known in the art and includes polysaccarides, dextran, heparin, fibronectin, poly(amino acids), starch, amylose, amylopectin, polypeptides, proteins, and derivatives thereof.

As used herein, the term “polymer” may refer to either a natural polymer or synthetic polymer.

As used herein, the term “poly(amino acid)” or “amino acid block” refers to a covalently linked amino acid chain wherein each monomer is an amino acid unit. Such amino acid units include natural and unnatural amino acids. In certain embodiments, each amino acid unit is in the L-configuration. Such poly(amino acids) include those having suitably protected functional groups. For example, amino acid monomers may have hydroxyl or amino moieties which are optionally protected by a suitable hydroxyl protecting group or a suitable amine protecting group, as appropriate. Such suitable hydroxyl protecting groups and suitable amine protecting groups are described in more detail herein, infra. As used herein, an amino acid block comprises one or more monomers or a set of two or more monomers. In certain embodiments, an amino acid block comprises one or more monomers such that the overall block is hydrophilic. In other embodiments, an amino acid block comprises one or more monomers such that the overall block is hydrophobic. In still other embodiments, amino acid blocks of the present invention include random amino acid blocks, ie blocks comprising a mixture of amino acid residues.

As used herein, the phrase “natural amino acid side-chain group” refers to the side-chain group of any of the 20 amino acids naturally occurring in proteins. Such natural amino acids include the nonpolar, or hydrophobic amino acids, glycine, alanine, valine, leucine isoleucine, methionine, phenylalanine, tryptophan, and proline. Cysteine is sometimes classified as nonpolar or hydrophobic and other times as polar. Natural amino acids also include polar, or hydrophilic amino acids, such as tyrosine, serine, threonine, aspartic acid (also known as aspartate, when charged), glutamic acid (also known as glutamate, when charged), asparagine, and glutamine. Certain polar, or hydrophilic, amino acids have charged side-chains. Such charged amino acids include lysine, arginine, and histidine. One of ordinary skill in the art would recognize that protection of a polar or hydrophilic amino acid side-chain can render that amino acid nonpolar. For example, a suitably protected tyrosine hydroxyl group can render that tyrosine nonpolar and hydrophobic by virtue of protecting the hydroxyl group.

As used herein, the phrase “unnatural amino acid side-chain group” refers to amino acids not included in the list of 20 amino acids naturally occurring in proteins, as described above. Such amino acids include the D-isomer of any of the 20 naturally occurring amino acids. Unnatural amino acids also include homoserine, ornithine, and thyroxine. Other unnatural amino acids side-chains are well know to one of ordinary skill in the art and include unnatural aliphatic side chains. Other unnatural amino acids include modified amino acids, including those that are N-alkylated, cyclized, phosphorylated, acetylated, amidated, azidylated, labelled, and the like.

As used herein, the phrase “living polymer chain-end” refers to the terminus resulting from a polymerization reaction having maintained chain-end reactivity after the completion of the reaction.

As used herein, the term “termination” refers to attaching a terminal group to a polymer chain-end by the reaction of a living polymer with an appropriate compound. Alternatively, the term “termination” may refer to attaching a terminal group to a hydroxyl end, or derivative thereof, of the polymer chain.

As used herein, the term “polymerization terminator” is used interchangeably with the term “polymerization terminating agent” and refers to a compound for attaching a terminal group to a polymer chain-end of a living polymer. Alternatively, the term “polymerization terminator” may refer to a compound for attaching a terminal group to a hydroxyl end, or derivative thereof, of the polymer chain.

As used herein, the term “polymerization initiator” refers to a compound, or anion thereof, which reacts with the desired monomer in a manner which results in polymerization of that monomer. In certain embodiments, the polymerization initiator is the anion of a functional group which initiates the polymerization of ethylene oxide. In other embodiments, the polymerization initiator is the amine salt described herein.

As described herein, compounds of the invention may optionally be substituted with one or more substituents, such as are illustrated generally above, or as exemplified by particular classes, subclasses, and species of the invention. It will be appreciated that the phrase “optionally substituted” is used interchangeably with the phrase “substituted or unsubstituted.” In general, the term “substituted”, whether preceded by the term “optionally” or not, refers to the replacement of hydrogen radicals in a given structure with the radical of a specified substituent. Unless otherwise indicated, an optionally substituted group may have a substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position. Combinations of substituents envisioned by this invention are preferably those that result in the formation of stable or chemically feasible compounds.

The term “stable”, as used herein, refers to compounds that are not substantially altered when subjected to conditions to allow for their production, detection, and preferably their recovery, purification, and use for one or more of the purposes disclosed herein. In some embodiments, a stable compound or chemically feasible compound is one that is not substantially altered when kept at a temperature of 40° C. or less, in the absence of moisture or other chemically reactive conditions, for at least a week.

The term “aliphatic” or “aliphatic group”, as used herein, means a straight-chain (i.e., unbranched) or branched, substituted or unsubstituted hydrocarbon chain that is completely saturated or that contains one or more units of unsaturation, or a monocyclic hydrocarbon or bicyclic hydrocarbon that is completely saturated or that contains one or more units of unsaturation, but which is not aromatic (also referred to herein as “carbocycle” “cycloaliphatic” or “cycloalkyl”), that has a single point of attachment to the rest of the molecule. Unless otherwise specified, aliphatic groups contain 1-20 aliphatic carbon atoms. In some embodiments, aliphatic groups contain 1-10 aliphatic carbon atoms. In other embodiments, aliphatic groups contain 1-8 aliphatic carbon atoms. In still other embodiments, aliphatic groups contain 1-6 aliphatic carbon atoms, and in yet other embodiments aliphatic groups contain 1-4 aliphatic carbon atoms. In some embodiments, “cycloaliphatic” (or “carbocycle” or “cycloalkyl”) refers to a monocyclic C3-C8 hydrocarbon or bicyclic C8-C12 hydrocarbon that is completely saturated or that contains one or more units of unsaturation, but which is not aromatic, that has a single point of attachment to the rest of the molecule wherein any individual ring in said bicyclic ring system has 3-7 members. Suitable aliphatic groups include, but are not limited to, linear or branched, substituted or unsubstituted alkyl, alkenyl, alkynyl groups and hybrids thereof such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

The term “heterocycle”, “heterocyclyl”, “heterocycloaliphatic”, or “heterocyclic” as used herein means non-aromatic, monocyclic, bicyclic, or tricyclic ring systems in which one or more ring members is an independently selected heteroatom. In some embodiments, the “heterocycle”, “heterocyclyl”, “heterocycloaliphatic”, or “heterocyclic” group has three to fourteen ring members in which one or more ring members is a heteroatom independently selected from oxygen, sulfur, nitrogen, or phosphorus, and each ring in the system contains 3 to 7 ring members.

The term “heteroatom” means one or more of oxygen, sulfur, nitrogen, phosphorus, or silicon (including, any oxidized form of nitrogen, sulfur, phosphorus, or silicon; the quaternized form of any basic nitrogen or; a substitutable nitrogen of a heterocyclic ring, for example N (as in 3,4-dihydro-2H-pyrrolyl), NH (as in pyrrolidinyl) or NR+ (as in N-substituted pyrrolidinyl).

The term “unsaturated”, as used herein, means that a moiety has one or more units of unsaturation.

The term “alkoxy”, or “thioalkyl”, as used herein, refers to an alkyl group, as previously defined, attached to the principal carbon chain through an oxygen (“alkoxy”) or sulfur (“thioalkyl”) atom.

The terms “haloalkyl”, “haloalkenyl” and “haloalkoxy” means alkyl, alkenyl or alkoxy, as the case may be, substituted with one or more halogen atoms. The term “halogen” means F, Cl, Br, or I.

The term “aryl” used alone or as part of a larger moiety as in “aralkyl”, “aralkoxy”, or “aryloxyalkyl”, refers to monocyclic, bicyclic, and tricyclic ring systems having a total of five to fourteen ring members, wherein at least one ring in the system is aromatic and wherein each ring in the system contains 3 to 7 ring members. The term “aryl” may be used interchangeably with the term “aryl ring”. The term “aryl” also refers to heteroaryl ring systems as defined hereinbelow.

The term “heteroaryl”, used alone or as part of a larger moiety as in “heteroaralkyl” or “heteroarylalkoxy”, refers to monocyclic, bicyclic, and tricyclic ring systems having a total of five to fourteen ring members, wherein at least one ring in the system is aromatic, at least one ring in the system contains one or more heteroatoms, and wherein each ring in the system contains 3 to 7 ring members. The term “heteroaryl” may be used interchangeably with the term “heteroaryl ring” or the term “heteroaromatic”.

An aryl (including aralkyl, aralkoxy, aryloxyalkyl and the like) or heteroaryl (including heteroaralkyl and heteroarylalkoxy and the like) group may contain one or more substituents. Suitable substituents on the unsaturated carbon atom of an aryl or heteroaryl group are selected from halogen; N3, CN, Ro; ORo; SRo; 1,2-methylene-dioxy; 1,2-ethylenedioxy; phenyl (Ph) optionally substituted with Ro; —O(Ph) optionally substituted with Ro; (CH2)1-2(Ph), optionally substituted with Ro; CH═CH(Ph), optionally substituted with Ro; NO2; CN; N(Ro)2; NRoC(O)Ro; NRoC(O)N(Ro)2; NRoCO2Ro; —NRoNRoC(O)Ro; NRoNRoC(O)N(Ro)2; NRoNRoCO2Ro; C(O)C(O)Ro; C(O)CH2C(O)Ro; CO2Ro; C(O)Ro; C(O)N(Ro)2; OC(O)N(Ro)2; S(O)2Ro; SO2N(Ro)2; S(O)Ro; NRoSO2N(Ro)2; NRoSO2Ro; C(═S)N(Ro)2; C(═NH)—N(Ro)2; or (CH2)0-2NHC(O)Ro wherein each independent occurrence of Ro is selected from hydrogen, optionally substituted C1-6 aliphatic, an unsubstituted 5-6 membered heteroaryl or heterocyclic ring, phenyl, O(Ph), or CH2(Ph), or, notwithstanding the definition above, two independent occurrences of Ro, on the same substituent or different substituents, taken together with the atom(s) to which each Ro group is bound, form a 3-8 membered cycloalkyl, heterocyclyl, aryl, or heteroaryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Optional substituents on the aliphatic group of Ro are selected from N3, CN, NH2, NH(C1-4aliphatic), N(C1-4aliphatic)2, halogen, C1-4aliphatic, OH, O(C1-4aliphatic), NO2, CN, CO2H, CO2(C1-4aliphatic), O(haloC1-4aliphatic), or haloC1-4aliphatic, wherein each of the foregoing C1-4aliphatic groups of Ro is unsubstituted.

An aliphatic or heteroaliphatic group or a non-aromatic heterocyclic ring may contain one or more substituents. Suitable substituents on the saturated carbon of an aliphatic or heteroaliphatic group, or of a non-aromatic heterocyclic ring are selected from those listed above for the unsaturated carbon of an aryl or heteroaryl group and additionally include the following: ═O, ═S, ═NNHR*, ═NN(R*)2, ═NNHC(O)R*, ═NNHCO2(alkyl), ═NNHSO2(alkyl), or ═NR*, where each R* is independently selected from hydrogen or an optionally substituted C1-6 aliphatic. Optional substituents on the aliphatic group of R* are selected from NH2, NH(C1-4 aliphatic), N(C1-4 aliphatic)2, halogen, C1-4 aliphatic, OH, O(C1-4 aliphatic), NO2, CN, CO2H, CO2(C1-4 aliphatic), O(halo C1-4 aliphatic), or halo(C1-4 aliphatic), wherein each of the foregoing C1-4aliphatic groups of R* is unsubstituted.

Optional substituents on the nitrogen of a non-aromatic heterocyclic ring are selected from R+, N(R+)2, C(O)R+, CO2R+, C(O)C(O)R+, C(O)CH2C(O)R+, SO2R+, SO2N(R+)2, C(═S)N(R+)2, C(═NH)—N(R+)2, or NR+SO2R+; wherein R+ is hydrogen, an optionally substituted C1-6 aliphatic, optionally substituted phenyl, optionally substituted O(Ph), optionally substituted CH2(Ph), optionally substituted (CH2)1-2(Ph); optionally substituted CH═CH(Ph); or an unsubstituted 5-6 membered heteroaryl or heterocyclic ring having one to four heteroatoms independently selected from oxygen, nitrogen, or sulfur, or, notwithstanding the definition above, two independent occurrences of R+, on the same substituent or different substituents, taken together with the atom(s) to which each R+ group is bound, form a 3-8-membered cycloalkyl, heterocyclyl, aryl, or heteroaryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Optional substituents on the aliphatic group or the phenyl ring of R+ are selected from NH2, NH(C1-4 aliphatic), N(C1-4 aliphatic)2, halogen, C1-4 aliphatic, OH, O(C1-4 aliphatic), NO2, CN, CO2H, CO2(C1-4 aliphatic), O(halo C1-4 aliphatic), or halo(C1-4 aliphatic), wherein each of the foregoing C1-4aliphatic groups of R+ is unsubstituted.

As detailed above, in some embodiments, two independent occurrences of Ro (or R+, or any other variable similarly defined herein), are taken together with the atom(s) to which each variable is bound to form a 3-8-membered cycloalkyl, heterocyclyl, aryl, or heteroaryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Exemplary rings that are formed when two independent occurrences of Ro (or R+, or any other variable similarly defined herein) are taken together with the atom(s) to which each variable is bound include, but are not limited to the following: a) two independent occurrences of Ro (or R+, or any other variable similarly defined herein) that are bound to the same atom and are taken together with that atom to form a ring, for example, N(Ro)2, where both occurrences of Ro are taken together with the nitrogen atom to form a piperidin-1-yl, piperazin-1-yl, or morpholin-4-yl group; and b) two independent occurrences of Ro (or R+, or any other variable similarly defined herein) that are bound to different atoms and are taken together with both of those atoms to form a ring, for example where a phenyl group is substituted with two occurrences of ORo

these two occurrences of Ro are taken together with the oxygen atoms to which they are bound to form a fused 6-membered oxygen containing ring

It will be appreciated that a variety of other rings can be formed when two independent occurrences of Ro (or R+, or any other variable similarly defined herein) are taken together with the atom(s) to which each variable is bound and that the examples detailed above are not intended to be limiting.

Unless otherwise stated, structures depicted herein are also meant to include all isomeric (e.g., enantiomeric, diastereomeric, and geometric (or conformational)) forms of the structure; for example, the R and S configurations for each asymmetric center, (Z) and (E) double bond isomers, and (Z) and (E) conformational isomers. Therefore, single stereochemical isomers as well as enantiomeric, diastereomeric, and geometric (or conformational) mixtures of the present compounds are within the scope of the invention. Unless otherwise stated, all tautomeric forms of the compounds of the invention are within the scope of the invention. Additionally, unless otherwise stated, structures depicted herein are also meant to include compounds that differ only in the presence of one or more isotopically enriched atoms. For example, compounds having the present structures except for the replacement of hydrogen by deuterium or tritium, or the replacement of a carbon by a 13C- or 14C-enriched carbon are within the scope of this invention. Such compounds are useful, for example, as analytical tools or probes in biological assays.

As used herein, the term “detectable moiety” is used interchangeably with the term “label” and relates to any moiety capable of being detected, e.g., primary labels and secondary labels. Primary labels, such as radioisotopes (e.g., 32P, 33P, 35S, or 14C), mass-tags, and fluorescent labels are signal generating reporter groups which can be detected without further modifications.

The term “secondary label” as used herein refers to moieties such as biotin and various protein antigens that require the presence of a second intermediate for production of a detectable signal. For biotin, the secondary intermediate may include streptavidin-enzyme conjugates. For antigen labels, secondary intermediates may include antibody-enzyme conjugates. Some fluorescent groups act as secondary labels because they transfer energy to another group in the process of nonradiative fluorescent resonance energy transfer (FRET), and the second group produces the detected signal.

The terms “fluorescent label”, “fluorescent dye”, and “fluorophore” as used herein refer to moieties that absorb light energy at a defined excitation wavelength and emit light energy at a different wavelength. Examples of fluorescent labels include, but are not limited to: Alexa Fluor dyes (Alexa Fluor 350, Alexa Fluor 488, Alexa Fluor 532, Alexa Fluor 546, Alexa Fluor 568, Alexa Fluor 594, Alexa Fluor 633, Alexa Fluor 660 and Alexa Fluor 680), AMCA, AMCA-S, BODIPY dyes (BODIPY FL, BODIPY R6G, BODIPY TMR, BODIPY TR, BODIPY 530/550, BODIPY 558/568, BODIPY 564/570, BODIPY 576/589, BODIPY 581/591, BODIPY 630/650, BODIPY 650/665), Carboxyrhodamine 6G, carboxy-X-rhodamine (ROX), Cascade Blue, Cascade Yellow, Coumarin 343, Cyanine dyes (Cy3, Cy5, Cy3.5, Cy5.5), Dansyl, Dapoxyl, Dialkylaminocoumarin, 4′,5′-Dichloro-2′,7′-dimethoxy-fluorescein, DM-NERF, Eosin, Erythrosin, Fluorescein, FAM, Hydroxycoumarin, IRDyes (IRD40, IRD 700, IRD 800), JOE, Lissamine rhodamine B, Marina Blue, Methoxycoumarin, Naphthofluorescein, Oregon Green 488, Oregon Green 500, Oregon Green 514, Pacific Blue, PyMPO, Pyrene, Rhodamine B, Rhodamine 6G, Rhodamine Green, Rhodamine Red, Rhodol Green, 2′,4′,5′,7′-Tetra-bromosulfone-fluorescein, Tetramethyl-rhodamine (TMR), Carboxytetramethylrhodamine (TAMRA), Texas Red, Texas Red-X.

The term “mass-tag” as used herein refers to any moiety that is capable of being uniquely detected by virtue of its mass using mass spectrometry (MS) detection techniques. Examples of mass-tags include electrophore release tags such as N-[3-[4′-[(p-Methoxytetrafluorobenzyl)oxy]phenyl]-3-methylglyceronyl]isonipecotic Acid, 4′-[2,3,5,6-Tetrafluoro-4-(pentafluorophenoxyl)]methyl acetophenone, and their derivatives. The synthesis and utility of these mass-tags is described in U.S. Pat. Nos. 4,650,750, 4,709,016, 5,360,8191, 5,516,931, 5,602,273, 5,604,104, 5,610,020, and 5,650,270. Other examples of mass-tags include, but are not limited to, nucleotides, dideoxynucleotides, oligonucleotides of varying length and base composition, oligopeptides, oligosaccharides, and other synthetic polymers of varying length and monomer composition. A large variety of organic molecules, both neutral and charged (biomolecules or synthetic compounds) of an appropriate mass range (100-2000 Daltons) may also be used as mass-tags.

The term “metal substrate”, as used herein refers to any metallic material which may be modified to incorporate hydroxyl groups to which a functionalized end-group of a polymeric or small molecule organic group can be attached.

As described generally above, the present invention provides a method for covalently modifying a metal substrate, comprising the steps of introducing hydroxyl groups onto the metal substrate to produce a hydrophilic metal surface and covalently bonding a polymer or small molecule organic moiety onto the hydrophilic metal surface. As used herein, the phrase “hydrophilic metal surface” refers to a metal substrate onto which a plurality of hydroxyl groups has been incorporated. One of ordinary skill in the art would recognize that various metallic substrates are amenable to methods of the present invention. In certain embodiments, the metal substrate is any such substrate that comprises iron. In other embodiments, the metal substrate comprises a stainless steel, a cobalt alloy, or a titanium alloy. In still other embodiments, the metal substrate comprises iron, iron alloys, steel, stainless steel, austenitic stainless steel, Type 316 stainless steel, ferritic stainless steel, martensitic stainless steel, duplex stainless steel, cobalt, cobalt alloys, cobalt-chromium alloys, stellite alloys, Vitallium®, titanium, titanium alloys, nickel-titanium alloys, nitinol, or super-alloys.

Hydrophilic metal surfaces can be prepared with the use of oxygen and/or water plasmas. (Kim et. al. Surface and Coatings Technology, 2003, 171, 312-316). It has been shown that hydroxyl groups, in the form of Fe(OH)2, are the source of this hydrophilicity on the metal surface. (Suzuki et. al. Surface and Coatings Technology 2005, 200, 284-287). This strategy extends to a number of iron-based metals and alloys such as iron, iron alloys, steel, stainless steel, austenitic stainless steel, Type 316 stainless steel, ferritic stainless steel, martensitic stainless steel, and duplex stainless steel. Other suitable metal substrates include cobalt, cobalt alloys, cobalt-chromium alloys, stellite alloys, Vitallium®, titanium, titanium alloys, nickel-titanium alloys, nitinol, and super-alloys. The geometry of the metal substrate includes, but is not limited to, flat surfaces, curved surfaces, cylinders, spheres, wire mesh, and tubing.

Using chemical functionality on the surface of plasma-treated metals, it would be advantageous to perform additional chemical modification of the substrate through dehydration or condensation reactions. Such reactions proceed on the hydrophilic metal surface without the need for additional reagents or catalysts. Chemical functionalities that undergo dehydration reactions with the plasma-modified metal substrates include, but are not limited to, phosphonic acids, silyl-alcohols and carboxylic acids. (Raman, A.; Gawalt, E. S. Langmuir, 2007, 23, 2284-2288. Raman, A. et. al. Langmuir, 2006, 22, 6469-6472. Gao, W. et al. Langmuir, 1996, 12, 6429-6435.) In addition, phosphonic halides, acyl halides, and silyl-halides can undergo condensation reactions with hydroxyl functionalized metal surfaces to afford the desired modified metallic material.

In certain embodiments, the dehydration reaction is carried out by first incubating the hydrophilic metal surface with the suitable functional molecule in an aqueous or organic solution. Without wishing to be bound by any particular theory, it is believed that during incubation, hydrogen bonding promotes the interaction of the functional molecule with the modified metal surface. This hydrogen-bonded intermediate is then converted to a covalent bond by subsequent dehydration. In certain embodiments, the dehydration step is performed at reduced pressure and/or elevated temperature. In other embodiments, the condensation reaction of acid-halide or silyl halide functional molecules and hydroxyl-functionalized metal substrates is performed using anhydrous conditions in dry organic solvents, leading directly to the desired covalently modified metal surface. One of ordinary still in the art will appreciate that the covalent bond forming reactions contemplated by the present invention are not limited to dehydration and condensation reactions and include, for example, addition reactions.

The introduction of hydroxyl groups onto a metal surface is well known to one of ordinary skill in the art. One of ordinary skill would recognize that there are multiple methods for accomplishing the functionalization of a metal substrate. One such method is the oxidation of iron atoms found in metal substrates. Such oxidation is well known in the art and includes cold plasma methods as described by, e.g., Suzuki, et al, Surface & Coatings Technology, (2005) 284-287. In certain embodiments, the metal substrate is oxidized with water vapor plasma.

As described generally above, the functionalized metal surface is covalently bonded to a polymer or a small molecule organic moiety. One of ordinary skill in the art would appreciate that hydroxyl groups are covalently bonded to a variety of other functional groups (e.g., with carboxylic acids to form esters thereof) by condensation or dehydration reaction. All such functional groups capable of covalently bonding to the hydroxyl groups incorporated onto the metal surface are contemplated. In certain embodiments, the polymer or small molecule organic moiety comprises one or more functional groups capable of covalently bonding to one or more hydroxyl groups incorporated onto the metal surface. Exemplary functional groups include, but are not limited to, phosphonic acids, silyl-alcohols, carboxylic acids, phosphonic halides, acyl halides, and silyl-halides.

Polymeric groups for use in the present invention comprise one or more functional groups capable of covalently bonding with one or more hydroxyl groups incorporated onto the metal surface. It will be appreciated that many such polymeric groups are amenable to this reaction. These polymeric groups include natural or synthetic polymers and copolymers. Exemplary polymers include mono-functionalized PEG\'s, poly(amino acids), heterobifunctional PEG\'s, branched PEG\'s, heterofunctionalized branched PEG\'s, PEG-b-PAA-b-PAA block copolymer, PEG-b-PAA-b-PEG block copolymers, PEG-b-polyester-b-PEG block copolymers, PEG-b-PAA block copolymers, [where PAA refers to poly(amino acid)], dextran, heparin, fibronectin, chitosan, amylose, amylopectin, glycogen, xanthan, gellan, pullulun, cellulose, and cellulose acetate.

In certain embodiments, the present invention provides a method for preparing a covalently modified metal surface, comprising the steps of:

(a) modifying a metal substrate to incorporate thereon a plurality of hydroxyl groups; (b) providing a compound of formula I:

R1—W  I

wherein: R1 is a natural or synthetic polymer or copolymer group or a small molecule organic group; W is —C(═O)OH, —C(═O)X, —P(═O)(OH)2, —P(═O)(X)2, —P(═O)(Ra)OH, —P(═O)(Ra)X, —O—S(═O)2OH, —S(═O)2OH, —Si(Ra)2OH, —Si(ORa)2OH, —Si(Ra)2X, —Si(Ra)(OH)2, —Si(Ra)X2, —Si(ORa)2X, C(═O)H, —N═C═S, —N═C═O, phenol, thiophenol, or an epoxide; each X is independently Cl, Br, or I; and each Ra is hydrogen, an alkyl group, or an aryl group; and (c) coupling the compound of formula I to one or more of the hydroxyl groups on the metal surface.

As described generally above, the coupling step (c) can be performed in the absence of reagents or catalysts by dehydration or condensation. However, it is also contemplated that the coupling step (c) can be performed in the presence of such reagents or catalysts. For example, coupling step (c) may be performed in the presence of a suitable base. Suitable bases include any of those known to one of ordinary skill in the art for such coupling reactions. Exemplary bases include, but are not limited to, triethylamine, diisopropylamine, diisopropylethylamine, dimethylaminopyridine, and the like.

One of ordinary skill in the art will appreciate that when W is —C(═O)X, —P(═O)(X)2, —P(═O)(Ra)X, —Si(Ra)2X, or —Si(ORa)2X, then the coupling at step (c) can occur by a condensation reaction. See FIGS. 2, 4, 6, 8, 10, and 12 which depict representative methods of the present invention whereby coupling step (c) occurs by condensation reaction.

Similarly, when W is —C(═O)OH, —P(═O)(OH)2, —P(═O)(Ra)OH, —Si(Ra)2OH, or —Si(ORa)2OH, the coupling at step (c) can occur by a dehydration reaction. See FIGS. 1, 3, 5, 7, 9, and 11 which depict representative methods of the present invention whereby coupling step (c) occurs by dehydration reaction.

In certain embodiments, the metal substrate comprises iron, iron alloys, steel, stainless steel, austenitic stainless steel, Type 316 stainless steel, ferritic stainless steel, martensitic stainless steel, duplex stainless steel, cobalt, cobalt alloys, cobalt-chromium alloys, stellite alloys, Vitallium®, titanium, titanium alloys, nickel-titanium alloys, nitinol, or super-alloys.

In other embodiments, R1 is a synthetic polymer such as linear homopolymers, branched homopolymers, block copolymers, branched block copolymers, star polymers, star copolymers, graft copolymers, hyperbranched copolymers, and dendrimers. In still other embodiments, R1 is a natural polymer such as oligopeptides, proteins, polynucleic acids (e.g. DNA and RNA), oligosaccharides, and polysaccharides. According to another aspect of the present invention, R1 is poly(ethylene glycol) (PEG), a heterobifunctional PEG, a branched PEG, heterofunctionalized branched PEG\'s, PEG-b-PAA-b-PAA block copolymer, PEG-b-PAA-b-PEG block copolymers, PEG-b-polyester-b-PEG block copolymers, PEG-b-PAA block copolymers, [where PAA refers to poly(amino acid)], dextran, heparin, fibronectin, chitosan, amylose, amylopectin, glycogen, xanthan, gellan, pullulun, cellulose, and cellulose acetate.

In certain embodiments, R1 is a small molecule organic group. In other embodiments, R1 is selected from monosaccharides (e.g., glucose, galactose, fructose) and disaccharides (e.g., sucrose, lactose, maltose), phosphorylcholines, phosoplipids, cyclodextrans, and small molecule drugs.

In other embodiments, the present invention provides a method for preparing a covalently modified metal surface, comprising the steps of:

(a) providing a metal surface having a plurality of hydroxyl groups; (b) providing a compound of formula I:

R1—W  I

wherein: R1 is a natural or synthetic polymer or copolymer group or a small molecule organic group; W is —C(═O)OH, —C(═O)X, —P(═O)(OH)2, —P(═O)(X)2, —P(═O)(Ra)OH, —P(═O)(Ra)X, —O—S(═O)2OH, —S(═O)2OH, —Si(Ra)2OH, —Si(ORa)2OH, —Si(Ra)2X, —Si(Ra)(OH)2, —Si(Ra)X2, —Si(ORa)2X, C(═O)H, —N═C═S, —N═C═O, phenol, thiophenol, or an epoxide; each X is independently Cl, Br, or I; and each Ra is hydrogen, an alkyl group, or an aryl group; and (c) coupling the compound of formula I to one or more of the hydroxyl groups on the metal surface.

As defined generally above, R1 is a natural or synthetic polymer or copolymer group or a small molecule organic group. In certain embodiments, R1 is a poly(alkylene oxide) group or a branched poly(alkylene oxide). In other embodiments, R1 is a poly(ethylene glycol) group (“PEG”). PEG\'s are well known to one of ordinary skill in the art and include those described in detail in International Patent Application publication number WO2006/047419, U.S. Provisional Patent Application Ser. No. 60/795,412, filed Apr. 27, 2006, and U.S. Provisional Patent Application Ser. No. 60/795,374, filed Apr. 27, 2006, the entirety of each of which is hereby incorporated herein by reference. According to another aspect of the present invention, R1 is a group of formula II:

or a salt thereof, wherein: y is 0-2500; R2 is hydrogen, halogen, NO2, CN, N3, —N═C═O, —C(R)═NN(R)2, —P(O)(OR)2, —P(O)(X′)2, a small molecule drug, a 9-30 membered crown ether, a mono-protected amine, a di-protected amine, a protected aldehyde, a protected hydroxyl, a protected carboxylic acid, a protected thiol, or an optionally substituted group selected from aliphatic, a 3-8 membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a detectable moiety; each X′ is independently halogen; each R is independently hydrogen or an optionally substituted aliphatic group; L1 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L1 are independently replaced by -Cy-, —O—, —NR—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —SO—, —SO2—, —NRSO2—, —SO2NR—, —NRC(O)—, —C(O)NR—, —OC(O)NR—, or —NRC(O)O—, wherein: each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and L2 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L2 are independently replaced by -Cy-, —O—, —NR—, —S—, or —C(O)—, wherein: each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

As defined generally above, the y group of formula II is 0-2500. In certain embodiments, the y group of formula II is 0. In certain embodiments, the present invention provides compounds of formula II, as described above, wherein y is about 225. In other embodiments, y is about 10 to about 40. In other embodiments, y is about 40 to about 60. In still other embodiments, y is about 90 to about 150. In still other embodiments, y is about 200 to about 250. In other embodiments, y is about 300 to about 375. In other embodiments, y is about 400 to about 500. In still other embodiments, y is about 650 to about 750. In still other embodiments, y is about 1 to about 10.

In certain embodiments, R2 is optionally substituted aliphatic. In other embodiments, R2 is an unsubstituted aliphatic. In some embodiments, said R2 moiety is an optionally substituted alkyl group. In other embodiments, said R2 moiety is an optionally substituted alkynyl or alkenyl group. Such groups include methyl, t-butyl, 5-norbornene-2-yl, octane-5-yl, —C≡CH, —CH2C≡CH, —CH2CH2C≡CH, and —CH2CH2CH2C≡CH. When said R2 moiety is a substituted aliphatic group, suitable substituents on R2 include any of CN, N3, NO2, —CO2H, —SH, —NH2, —C(O)H, —NHC(O)Ro, —NHC(S)Ro, —NHC(O)NRo2, —NHC(S)NRo2, —NHC(O)ORo, —NHNHC(O)Ro, —NHNHC(O)NRo2, —NHNHC(O)ORo, —C(O)Ro, —C(S)Ro, —C(O)ORo, —C(O)SRo, —C(O)OSiRo3, —OC(O)Ro, SC(S)SRo, —SC(O)Ro, —C(O)N(Ro)2, —C(S)N(Ro)2, —C(S)SRo, —SC(S)SRo, —OC(O)N(Ro)2, —C(O)NHN(Ro)2, —C(O)N(ORo)Ro, —C(O)C(O)Ro, —C(O)CH2C(O)Ro, —C(NORo)Ro, —SSRo, —S(O)2Ro, —S(O)2ORo, —OS(O)2Ro, —S(O)2N(Ro)2, —S(O)Ro, —N(Ro)S(O)2N(Ro)2, —N(Ro)S(O)2Ro, —N(ORo)Ro, —C(NH)N(Ro)2, —P(O)2Ro, —P(O)(Ro)2, —OP(O)(Ro)2, or —OP(O)(ORo)2, wherein each Ro is as defined herein.

In other embodiments, R2 is an aliphatic group optionally substituted with any of Cl, Br, I, F, —NH2, —OH, —SH, —CO2H, —C(O)H, —C(O)(C1-6 aliphatic), —NHC(O)(C1-6 aliphatic), —NHC(O)NH2, —NHC(O)NH(C1-6 aliphatic), —NHC(S)NH—, —NHC(S)N(C1-6 aliphatic)2, —NHC(O)O(C1-6 aliphatic), —NHNH2, —NHNHC(O)(C1-6 aliphatic), —NHNHC(O)NH2, —NHNHC(O)NH(C1-6 aliphatic), —NHNHC(O)O(C1-6 aliphatic), —C(O)NH2, —C(O)NH(C1-6 aliphatic)2, —C(O)NHNH2, —C(S)N(C1-6 aliphatic)2, —OC(O)NH(C1-6 aliphatic), —C(O)C(O)(C1-6 aliphatic), —C(O)CH2C(O)(C1-6 aliphatic), —S(O)2(C1-6 aliphatic), —S(O)2O(C1-6 aliphatic), —OS(O)2(C1-6 aliphatic), —S(O)2NH(C1-6 aliphatic), —S(O)(C1-6 aliphatic), —NHS(O)2NH(C1-6 aliphatic), —NHS(O)2(C1-6 aliphatic), —P(O)2(C1-6 aliphatic), —P(O)(C1-6 aliphatic)2, —OP(O)(C1-6 aliphatic)2, or —OP(O)(OC1-6 aliphatic)2.

In certain embodiments, the R2 group of formula II is a group suitable for Click chemistry. Click reactions tend to involve high-energy (“spring-loaded”) reagents with well-defined reaction coordinates, that give rise to selective bond-forming events of wide scope. Examples include nucleophilic trapping of strained-ring electrophiles (epoxide, aziridines, aziridinium ions, episulfonium ions), certain carbonyl reactivity (e.g., the reaction between aldehydes and hydrazines or hydroxylamines), and several cycloaddition reactions. The azide-alkyne 1,3-dipolar cycloaddition is one such reaction. Click chemistry is known in the art and one of ordinary skill in the art would recognize that certain R2 moieties of the present invention are suitable for Click chemistry.

According to one embodiment, the R2 group of formula II is an azide-containing group. According to another embodiment, the R2 group of formula II is an alkyne-containing group. In certain embodiments, the R2 group of formula II has a terminal alkyne moiety. According to another embodiment, the R2 group of formula II is an aldehyde-containing group. In certain embodiments, the R2 group of formula II has a terminal hydrazine moiety. In other embodiments, the R2 group of formula II has a terminal oxyamine moiety. In still other embodiments, the R2 group of formula II is a epoxide-containing group. In certain other embodiments, the R2 group of formula II has a terminal maleimide moiety.

In other embodiments, R2 is an optionally substituted 3-8 membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In certain embodiments, R2 is an optionally substituted 5-7 membered saturated or partially unsaturated ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In other embodiments, R2 is an optionally substituted phenyl ring or a 5-6 membered heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

In certain embodiments, the R2 group of formula II is an optionally substituted aryl group. Examples include optionally substituted phenyl, optionally substituted pyridyl, optionally substituted naphthyl, optionally substituted pyrenyl, optionally substituted triazole, optionally substituted imidazole, optionally substituted phthalimide, optionally substituted tetrazole, optionally substituted furan, and optionally substituted pyran. When said R2 moiety is a substituted aryl group, suitable substituents on R2 include any of Ro, CN, N3, NO2, —CH3, —CH2N3, t-butyl, 5-norbornene-2-yl, octane-5-yl, —CH═CH2, —CH2C≡CH, —CH2CH2C≡CH, —CH2CH2CH2C≡CH, Cl, Br, I, F, —NH2, —OH, —SH, —CO2H, —C(O)H, —CH2NH2, —CH2OH, —CH2SH, —CH2CO2H, —CH2C(O)H, —C(O)(C1-6 aliphatic), —NHC(O)(C1-6 aliphatic), —NHC(O)NH—, —NHC(O)NH(C1-6 aliphatic), —NHC(S)NH2, —NHC(S)N(C1-6 aliphatic)2, —NHC(O)O(C1-6 aliphatic), —NHNH2, —NHNHC(O)(C1-6 aliphatic), —NHNHC(O)NH2, —NHNHC(O)NH(C1-6 aliphatic), —NHNHC(O)O(C1-6 aliphatic), —C(O)NH2, —C(O)NH(C1-6 aliphatic)2, —C(O)NHNH2, —C(S)N(C1-6 aliphatic)2, —OC(O)NH(C1-6 aliphatic), —C(O)C(O)(C1-6 aliphatic), —C(O)CH2C(O)(C1-6 aliphatic), —S(O)2(C1-6 aliphatic), —S(O)2O(C1-6 aliphatic), —OS(O)2(C1-6 aliphatic), —S(O)2NH(C1-6 aliphatic), —S(O)(C1-6 aliphatic), —NHS(O)2NH(C1-6 aliphatic), —NHS(O)2(C1-6 aliphatic), —P(O)2(C1-6 aliphatic), —P(O)(C1-6 aliphatic)2, —OP(O)(C1-6 aliphatic)2, or —OP(O)(OC1-6 aliphatic)2.

Suitable substitutents on R2 further include bis-(4-ethynyl-benzyl)-amino, dipropargylamino, di-hex-5-ynyl-amino, di-pent-4-ynyl-amino, di-but-3-ynyl-amino, propargyloxy, hex-5-ynyloxy, pent-4-ynyloxy, di-but-3-ynyloxy, 2-hex-5-ynyloxy-ethyldisulfanyl, 2-pent-4-ynyloxy-ethyldisulfanyl, 2-but-3-ynyloxy-ethyldisulfanyl, 2-propargyloxy-ethyldisulfanyl, bis-benzyloxy-methyl, [1,3]dioxolan-2-yl, and [1,3]dioxan-2-yl.

In other embodiments, R2 is hydrogen.

According to one embodiment, R2 is methyl.

In certain embodiments, R2 is N3.

In other embodiments, R2 is an epoxide ring.

In certain embodiments, the R2 group of formula II is a crown ether. Examples of such crown ethers include 12-crown-4, 15-crown-5, and 18-crown-6.

In still other embodiments, R2 is a detectable moiety. Detectable moieties are known in the art and include those described herein. According to one aspect of the invention, the R2 group of formula II is a fluorescent moiety. Such fluorescent moieties are well known in the art and include coumarins, quinolones, benzoisoquinolones, hostasol, and Rhodamine dyes, to name but a few. Exemplary fluorescent moieties of R2 include anthracen-9-yl, pyren-4-yl, 9-H-carbazol-9-yl, the carboxylate of rhodamine B, and the carboxylate of coumarin 343. In certain embodiments, R2 is a detectable moiety selected from:

In certain embodiments, R2 is —P(O)(OR)2, or —P(O)(halogen)2. According to one aspect, the present invention provides a compound of formula II, wherein R2 is —P(O)(OH)2. According to another aspect, the present invention provides a compound of formula II, wherein R2 is —P(O)(Cl)2. One of ordinary skill in the art would recognize that when R2 is —P(O)(OR)2, or —P(O)(halogen)2, the R2 group is also capable of forming a covalent bond with the hydrophilic metal surface thus forming a “looped” attachment.

As defined generally above, the L1 group of formula II is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L1 are independently replaced by -Cy-, —O—, —NR—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —SO—, —SO2—, —NRSO2—, —SO2NR—, —NRC(O)—, —C(O)NR—, —OC(O)NR—, or —NRC(O)O—, wherein each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

In certain embodiments, L1 is a valence bond. In other embodiments, L1 is a bivalent, saturated C1-12 alkylene chain, wherein 0-6 methylene units of L1 are independently replaced by -Cy-, —O—, —NH—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —C(O)NH—, or —NHC(O)—, wherein each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In still other embodiments, L1 is a bivalent, saturated C1-6 alkylene chain, wherein 0-3 methylene units of L1 are independently replaced by -Cy-, —O—, —NH—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —C(O)NH—, or —NHC(O)—.

In certain embodiments, L1 is -Cy- (i.e. a C1 alkylene chain wherein the methylene unit is replaced by -Cy-), wherein -Cy- is an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. According to one aspect of the present invention, -Cy- is an optionally substituted bivalent aryl group. According to another aspect of the present invention, -Cy- is an optionally substituted bivalent phenyl group. In other embodiments, -Cy- is an optionally substituted 5-8 membered bivalent, saturated carbocyclic ring. In still other embodiments, -Cy- is an optionally substituted 5-8 membered bivalent, saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Exemplary -Cy- groups include bivalent rings selected from phenyl, pyridyl, pyrimidinyl, cyclohexyl, cyclopentyl, or cyclopropyl.

In certain embodiments, the L1 group of formula II is —O—, —S—, —NH—, or —C(O)O—. In other embodiments, the L1 group of formula II is -Cy-, —C(O)—, —C(O)NH—, —NHC(O)—, —NH—O—, or —O-Cy-CH2NH—O—. In still other embodiments, the L1 group of formula II is any of —OCH2—, —OCH2C(O)—, —OCH2CH2C(O)—, —OCH2CH2O—, —OCH2CH2S—, —OCH2CH2C(O)O—, —OCH2CH2NH—, —OCH2CH2NHC(O)—, —OCH2CH2C(O)NH—, and —NHC(O)CH2CH2C(O)O—. According to another aspect, the L1 group of formula II is any of —OCH2CH2NHC(O)CH2CH2C(O)O—, —OCH2CH2NHC(O)CH2OCH2C(O)O—, —OCH2CH2NHC(O)CH2OCH2C(O)NH—, —CH2C(O)NH—, —CH2C(O)NHNH—, or —OCH2CH2NHNH—.

As defined generally above, the R2 group of formula II is, inter alia, a mono-protected amine, a di-protected amine, a protected aldehyde, a protected hydroxyl, a protected carboxylic acid, or a protected thiol. Protected hydroxyl groups are well known in the art and include those described in detail in Protecting Groups in Organic Synthesis, T. W. Greene and P. G. M. Wuts, 3rd edition, John Wiley & Sons, 1999, the entirety of which is incorporated herein by reference. Examples of suitably protected hydroxyl groups further include, but are not limited to, esters, carbonates, sulfonates allyl ethers, ethers, silyl ethers, alkyl ethers, arylalkyl ethers, and alkoxyalkyl ethers. Examples of suitable esters include formates, acetates, proprionates, pentanoates, crotonates, and benzoates. Specific examples of suitable esters include formate, benzoyl formate, chloroacetate, trifluoroacetate, methoxyacetate, triphenylmethoxyacetate, p-chlorophenoxyacetate, 3-phenylpropionate, 4-oxopentanoate, 4,4-(ethylenedithio)pentanoate, pivaloate (trimethylacetate), crotonate, 4-methoxy-crotonate, benzoate, p-benzylbenzoate, 2,4,6-trimethylbenzoate. Examples of suitable carbonates include 9-fluorenylmethyl, ethyl, 2,2,2-trichloroethyl, 2-(trimethylsilyl)ethyl, 2-(phenylsulfonyl)ethyl, vinyl, allyl, and p-nitrobenzyl carbonate. Examples of suitable silyl ethers include trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, triisopropylsilyl ether, and other trialkylsilyl ethers. Examples of suitable alkyl ethers include methyl, benzyl, p-methoxybenzyl, 3,4-dimethoxybenzyl, trityl, t-butyl, and allyl ether, or derivatives thereof. Alkoxyalkyl ethers include acetals such as methoxymethyl, methylthiomethyl, (2-methoxyethoxy)methyl, benzyloxymethyl, beta-(trimethylsilyl)ethoxymethyl, and tetrahydropyran-2-yl ether. Examples of suitable arylalkyl ethers include benzyl, p-methoxybenzyl (MPM), 3,4-dimethoxybenzyl, O-nitrobenzyl, p-nitrobenzyl, p-halobenzyl, 2,6-dichlorobenzyl, p-cyanobenzyl, 2- and 4-picolyl ethers.

Protected amines are well known in the art and include those described in detail in Greene (1999). Suitable mono-protected amines further include, but are not limited to, aralkylamines, carbamates, allyl amines, amides, and the like. Examples of suitable mono-protected amino moieties include t-butyloxycarbonylamino (—NHBOC), ethyloxycarbonylamino, methyloxycarbonylamino, trichloroethyloxycarbonylamino, allyloxycarbonylamino (—NHAlloc), benzyloxocarbonyl amino (—NHCBZ), allylamino, benzylamino (—NHBn), fluorenylmethylcarbonyl (—NHFmoc), formamido, acetamido, chloroacetamido, dichloroacetamido, trichloroacetamido, phenylacetamido, trifluoroacetamido, benzamido, t-butyldiphenylsilyl, and the like. Suitable di-protected amines include amines that are substituted with two substituents independently selected from those described above as mono-protected amines, and further include cyclic imides, such as phthalimide, maleimide, succinimide, and the like. Suitable di-protected amines also include pyrroles and the like, 2,2,5,5-tetramethyl-[1,2,5]azadisilolidine and the like, and azide.

Protected aldehydes are well known in the art and include those described in detail in Greene (1999). Suitable protected aldehydes further include, but are not limited to, acyclic acetals, cyclic acetals, hydrazones, imines, and the like. Examples of such groups include dimethyl acetal, diethyl acetal, diisopropyl acetal, dibenzyl acetal, bis(2-nitrobenzyl)acetal, 1,3-dioxanes, 1,3-dioxolanes, semicarbazones, and derivatives thereof.

Protected carboxylic acids are well known in the art and include those described in detail in Greene (1999). Suitable protected carboxylic acids further include, but are not limited to, optionally substituted C1-6 aliphatic esters, optionally substituted aryl esters, silyl esters, activated esters, amides, hydrazides, and the like. Examples of such ester groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, benzyl, and phenyl ester, wherein each group is optionally substituted. Additional suitable protected carboxylic acids include oxazolines and ortho esters.

Protected thiols are well known in the art and include those described in detail in Greene (1999). Suitable protected thiols further include, but are not limited to, disulfides, thioethers, silyl thioethers, thioesters, thiocarbonates, and thiocarbamates, and the like. Examples of such groups include, but are not limited to, alkyl thioethers, benzyl and substituted benzyl thioethers, triphenylmethyl thioethers, and trichloroethoxycarbonyl thioester, to name but a few.

As defined generally above, the L2 group of formula II is L2 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L2 are independently replaced by -Cy-, —O—, —NR—, —S—, or —C(O)—, wherein each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

In certain embodiments, L2 is a valence bond. In other embodiments, L2 is a bivalent, saturated C1-12 alkylene chain, wherein 0-6 methylene units of L2 are independently replaced by -Cy-, or —O—, —NH—, wherein each -Cy- is independently an optionally substituted 5-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In still other embodiments, L2 is a bivalent, saturated C1-6 alkylene chain, wherein 0-2 methylene units of L2 are independently replaced by -Cy-.

In certain embodiments, L2 is -Cy- (i.e., a C1 alkylene chain wherein the methylene unit is replaced by -Cy-), wherein -Cy- is an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. According to one aspect of the present invention, -Cy- is an optionally substituted bivalent aryl group. According to another aspect of the present invention, -Cy- is an optionally substituted bivalent phenyl group. In other embodiments, -Cy- is an optionally substituted 5-8 membered bivalent, saturated carbocyclic ring. In still other embodiments, -Cy- is an optionally substituted 5-8 membered bivalent, saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Exemplary -Cy- groups include bivalent rings selected from phenyl, pyridyl, pyrimidinyl, cyclohexyl, cyclopentyl, or cyclopropyl.

In certain embodiments, the L2 group of formula II is —O—, —S—, —NH—, or —C(O)—. In still other embodiments, the L2 group of formula II is any of —OCH2—, —OCH2C(O)—, —OCH2CH2C(O)—, —OCH2CH2O—, or —OCH2CH2S—. In other embodiments, the L2 group of formula II is —OC(O)CH2CH2CH2CH2—, —OCH2CH2—, —NHC(O)CH2CH2—, —NHC(O)CH2CH2CH2—, —OC(O)CH2CH2CH2—, —O-Cy-, —O-Cy-CH2—, —O-Cy-NH—, —O-Cy-S—, —O-Cy-C(O)—, or —O-Cy-C(O)O-Cy-.

In certain embodiments, the present invention provides a method for preparing a covalently modified metal surface, comprising the steps of:

(a) modifying a metal substrate to incorporate thereon a plurality of hydroxyl groups; (b) providing a compound of formula II-a:

or a salt thereof, wherein: W is —C(═O)OH, —C(═O)X, —P(═O)(OH)2, —P(═O)(X)2, —P(═O)(Ra)OH, —P(═O)(Ra)X, —O—S(═O)2OH, —S(═O)2OH, —Si(Ra)2OH, —Si(ORa)2OH, —Si(Ra)2X, —Si(Ra)(OH)2, —Si(Ra)X2, —Si(ORa)2X, C(═O)H, —N═C═S, —N═C═O, phenol, thiophenol, or an epoxide; each X is independently Cl, Br, or I; and each Ra is hydrogen, an alkyl group, or an aryl group; y is 0-2500; R2 is hydrogen, halogen, NO2, CN, N3, —N═C═O, —C(R)═NN(R)2, —P(O)(OR)2, —P(O)(X′)2, a 9-30 membered crown ether, a mono-protected amine, a di-protected amine, a protected aldehyde, a protected hydroxyl, a protected carboxylic acid, a protected thiol, or an optionally substituted group selected from aliphatic, a 3-8 membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a detectable moiety; each X′ is independently halogen; each R is independently hydrogen or an optionally substituted aliphatic group; L1 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L1 are independently replaced by -Cy-, —O—, —NR—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —SO—, —SO2—, —NRSO2—, —SO2NR—, —NRC(O)—, —C(O)NR—, —OC(O)NR—, or —NRC(O)O—, wherein: each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and L2 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L2 are independently replaced by -Cy-, —O—, —NR—, —S—, or —C(O)—, wherein: each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur. and (c) coupling the compound of formula II-a to one or more of the hydroxyl groups on the metal surface.

Each of the R2, L1, y, and L2 groups of formula II-a are as described in classes and subclasses for compounds of formula II, both singly and in combination.

In other embodiments, the present invention provides a compound of formula II-a′:

or a salt thereof, wherein: W is —Si(Ra)2OH, —Si(ORa)2OH, —Si(Ra)2X, —Si(Ra)(OH)2, —Si(Ra)X2, or —Si(ORa)2X; each X is independently Cl, Br, or I; and each Ra is hydrogen, an alkyl group, or an aryl group; y is 0-2500; R2 is hydrogen, halogen, NO2, CN, N3, —N═C═O, —C(R)═NN(R)2, —P(O)(OR)2, —P(O)(X′)2, a 9-30 membered crown ether, a mono-protected amine, a di-protected amine, a protected aldehyde, a protected hydroxyl, a protected carboxylic acid, a protected thiol, or an optionally substituted group selected from aliphatic, a 3-8 membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a detectable moiety; each X′ is independently halogen; each R is independently hydrogen or an optionally substituted aliphatic group; L1 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L1 are independently replaced by -Cy-, —O—, —NR—, —S—, —OC(O)—, —C(O)O—, —C(O)—, —SO—, —SO2—, —NRSO2—, —SO2NR—, —NRC(O)—, —C(O)NR—, —OC(O)NR—, or —NRC(O)O—, wherein: each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and L2 is a valence bond or a bivalent, saturated or unsaturated, straight or branched C1-12 alkylene chain, wherein 0-6 methylene units of L2 are independently replaced by -Cy-, —O—, —NR—, —S—, or —C(O)—, wherein: each -Cy- is independently an optionally substituted 3-8 membered bivalent, saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an optionally substituted 8-10 membered bivalent saturated, partially unsaturated, or aryl bicyclic ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

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