Photoinduced alkyne-azide click reactions

1. A composition comprising an alkyne-based substrate, an azide-based substrate, at least one Cu(II) salt and at least one photoinducible reducing agent,

wherein said alkyne-based substrate comprises at least one reactive alkynyl group,

wherein said azide-based substrate comprises at least one reactive azide group, and

wherein exposure of at least a portion of said composition to electromagnetic radiation promotes formation of Cu(I), which catalyzes cycloaddition of said at least one reactive alkynyl group and said at least one reactive azide group.

2. The composition of claim 1 , wherein said alkyne-based substrate or said azide-based substrate is attached to a hydrogel.

3. The composition of claim 1 , wherein said at least one reactive alkynyl group is a terminal alkynyl group.

4. The composition of claim 1 , wherein the molar ratio of said at least one reactive alkyne group and said at least reactive azide group in said composition ranges from about 10 −2 to about 10 +2 .

5. The composition of claim 1 , wherein said at least one photoinducible reducing agent is a Type (I) photoinitiator.

6. The composition of claim 1 , wherein said at least one reducing agent is selected from the group consisting of: 1-hydroxy-cyclohexyl-phenyl-ketone; benzophenone; 2-hydroxy-2-methyl-1-phenyl-1-propanone; 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone; methyl benzoylformate; oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester; oxy-phenyl-acetic 2-[2-hydroxy-ethoxy]-ethyl ester; oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester; alpha,alpha-dimethoxy-alpha-phenyl acetophenone; 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl) phenyl]-1-butanone; 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone; diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide; bis-(eta 5-2,4-cyclopentadien-1-yl)-bis-[2,6-difluoro-3-(1H-pyrrol-1-yl) -phenyl]-titanium; (4-methylphenyl) [4-(2-methylpropyl) phenyl]-iodonium hexafluorophosphate; 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-butan-1-one; 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)-ketone; bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide; titanium dioxide; and mixtures thereof.

7. A method of preparing a compound of formula (I):

said method comprising the steps of:

(i) mixing a compound of formula (II):

R—C≡C—H  (II),

 a compound of formula (III):

R 1 —N 3   (III),

 at least one Cu(II) salt and at least one photoinducible reducing agent, to generate a first composition,

wherein R and R 1 are independently alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, heteroalkyl, substituted heteroalkyl, heteroalkenyl, substituted heteroalkenyl, aryl, substituted aryl, aryl-(C 1 -C 3 )alkyl, heterocyclyl, substituted heterocyclyl, heteroaryl, or substituted heteroaryl; and

(ii) exposing at least a portion of said first composition to electromagnetic radiation, whereby said at least one Cu(II) salt is at least partiallty reduced to a Cu(I) species, which catalyzes cycloaddition of said compound of formula (II) with said compound of formula (III) to form said compound of formula (I).

8. The method of claim 7 , wherein the molar ratio of said compound of formula (II) and said compound of formula (III) in said first composition ranges from about 0.5to about 2.

9. The method of claim 7 , wherein said at least one reducing agent is a Type (I) photoinitiator.

10. The method of claim 7 , wherein said at least one reducing agent is selected from the group consisting of: 1-hydroxy-cyclohexyl-phenyl-ketone; benzophenone; 2-hydroxy-2-methyl-1-phenyl-1-propanone; 2-hydroxy-1[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone; methyl benzoylformate; oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy -ethoxy]-ethyl ester; oxy-phenyl-acetic 2[2-hydroxy-ethoxy]-ethyl ester; oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester; alpha,alpha-dimethoxy-alpha-phenyl acetophenone; 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl) phenyl]-1-butanone; 2-methyl-1[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone; diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide; bis-(eta 5-2,4-cyclopentadien-1-yl)-bis-[2,6-difluoro-3-(1H-pyrrol-1-yl) -phenyl]-titanium; (4-methylphenyl) [4-(2-methylpropyl) phenyl]-iodonium hexafluorophosphate; 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-butan-1-one; 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)-ketone; bis-(2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl phosphine oxide; titanium dioxide; and mixtures thereof.

11. The method of claim 7 , wherein said electromagnetic radiation comprises ultraviolet or visible electromagnetic radiation.