title: Efficient functionalization of oxide-free silicon(111) surfaces: thiol-yne versus thiol-ene click chemistry.
abstract: Thiol-yne click (TYC) chemistry was utilized as a copper-free click reaction for the modification of alkyne-terminated monolayers on oxide-free Si(111) surfaces, and the results were compared with the analogous thiol-ene click (TEC) chemistry. A wide range of thiols such as 9-fluorenylmethoxy-carbonyl cysteine, thio-β-d-glucose tetraacetate, thioacetic acid, thioglycerol, thioglycolic acid, and 1H,1H,2H,2H-perfluorodecanethiol was immobilized using TYC under photochemical conditions, and all modified surfaces were characterized by static water contact angle measurements, X-ray photoelectron spectroscopy (including a simulation thereof by density functional calculations), and infrared absorption reflection spectroscopy. Surface-bound TYC proceeds with an efficiency of up to 1.5 thiols per alkyne group. This high surface coverage proceeds without oxidizing the Si surface. TYC yielded consistently higher surface coverages than TEC, due to double addition of thiols to alkyne-terminated monolayers. This also allows for the sequential and highly efficient attachment of two different thiols onto an alkyne-terminated monolayer.
authors.affiliation: Laboratory of Organic Chemistry, Wageningen University and Research Center, Dreijenplein 8, 6703 HB, Wageningen, The Netherlands.
authors.forename: Nagendra S
authors.initials: NS
authors.lastname: Bhairamadgi
authors.forename: Satesh
authors.initials: S
authors.lastname: Gangarapu
authors.forename: Mabel A
authors.initials: MA
authors.lastname: Caipa Campos
authors.forename: Jos M J
authors.initials: JM
authors.lastname: Paulusse
authors.forename: Cees J M
authors.initials: CJ
authors.lastname: van Rijn
authors.forename: Han
authors.initials: H
authors.lastname: Zuilhof
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D057930:Click Chemistry; D010087:Oxides / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000475:Alkenes; D000480:Alkynes; D010087:Oxides; D013438:Sulfhydryl Compounds; D012825:Silicon