Rate of interfacial electron transfer through the 1,2,3-triazole linkage.
The rate of electron transfer is measured to two ferrocene and one iron tetraphenylporphyrin redox species coupled through terminal acetylenes to azide-terminated thiol monolayers by the Cu(I)-catalyzed azide-alkyne cycloaddition (a Sharpless "click" reaction) to form the 1,2,3-triazole linkage. The high yield, chemoselectivity, convenience, and broad applicability of this triazole formation reaction make such a modular assembly strategy very attractive. Electron-transfer rate constants from greater than 60,000 to 1 s(-1) are obtained by varying the length and conjugation of the electron-transfer bridge and by varying the surrounding diluent thiols in the monolayer. Triazole and the triazole carbonyl linkages provide similar electronic coupling for electron transfer as esters. The ability to vary the rate of electron transfer to many different redox species over many orders of magnitude by using modular coupling chemistry provides a convenient way to study and control the delivery of electrons to multielectron redox catalysts and similar interfacial systems that require controlled delivery of electrons.
Devaraj
Neal K
NK
Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
Decreau
Richard A
RA
Ebina
Wataru
W
Collman
James P
JP
Chidsey
Christopher E D
CE
D000480:Alkynes / Q000737:chemistry; D001386:Azides / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D003500:Cyclization; D004566:Electrodes; D004583:Electrons; D005296:Ferrous Compounds / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D000075163:Metallocenes; D008665:Metalloporphyrins / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry
D000480:Alkynes; D001386:Azides; D005296:Ferrous Compounds; D000075163:Metallocenes; D008665:Metalloporphyrins; D013438:Sulfhydryl Compounds; D014230:Triazoles; C032547:iron tetraphenylporphyrin; D006046:Gold; D003300:Copper; C004998:ferrocene