Open AccessMolecular Surface Functionalization of Carbon Materials via Radical-Induced Grafting of Terminal Alkenes
Author(s) -
Yongqian Zhang,
Ali Abbaspour Tamijani,
Megan E. Taylor,
Bo Zhi,
Christy L. Haynes,
Sara E. Mason,
Robert J. Hamers
Publication year - 2019
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.9b02369
Subject(s) - chemistry , regioselectivity , steric effects , density functional theory , carbon fibers , monolayer , surface modification , x ray photoelectron spectroscopy , sn2 reaction , photochemistry , computational chemistry , organic chemistry , chemical engineering , catalysis , biochemistry , composite number , engineering , composite material , materials science
Formation of functional monolayers on surfaces of carbon materials is inherently difficult because of the high bond strength of carbon and because common pathways such as S N 2 mechanisms cannot take place at surfaces of solid materials. Here, we show that the radical initiators can selectively abstract H atoms from H-terminated carbon surfaces, initiating regioselective grafting of terminal alkenes to surfaces of diamond, glassy carbon, and polymeric carbon dots. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) demonstrate formation of self-terminating organic monolayers linked via the terminal C atom of 1-alkenes. Density functional theory (DFT) calculations suggest that this selectivity is at least partially thermodynamic in origin, as significantly less energy is needed to abstract H atoms from carbon surfaces as compared to typical aliphatic compounds. The regioselectivity favoring binding to the terminal C atom of the reactant alkenes arises from steric hindrance encountered in bond formation at the adjacent carbon atom. Our results demonstrate that carbon surface radical chemistry yields a versatile, selective, and scalable approach to monolayer formation on H-terminated carbon surfaces and provide mechanistic insights into the surface selectivity and regioselectivity of molecular grafting.