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Orientation of OH terminal groups in oligo(ethylene glycol)‐terminated self‐assemblies: results of ab initio modeling
Author(s) -
Malysheva Lyuba,
Onipko Alexander,
Liedberg Bo
Publication year - 2006
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200669158
Subject(s) - ethylene glycol , ab initio , monolayer , distortion (music) , chemistry , orientation (vector space) , crystallography , monomer , molecule , energy minimization , group (periodic table) , basis set , ab initio quantum chemistry methods , ethylene , computational chemistry , materials science , stereochemistry , geometry , nanotechnology , mathematics , organic chemistry , catalysis , polymer , amplifier , optoelectronics , cmos
Ab initio optimization of periodic arrays of HS(CH 2 ) 3 CONH‐EG 3 [EG n = (CH 2 CH 2 O) n H], which are used to model real self‐assembled monolayers (SAMs) terminated by oligomers of ethylene glycol (OEGs), favors a molecular geometry with a strong distortion of the OH tail group. The distortion effect is conformation dependent and appears exclusively in assemblies of helical OEGs. Helical SAM structures with the O–H bond directed towards the substrate surface exhibits a lower energy than the corresponding all trans SAMs with OH group oriented towards the vacuum interface. In view of strict limitations in molecular complexity and basis set for this kind of calculations, we tested the obtained molecular geometry as the starting point for performing optimization of the HS(CH 2 ) 15 CONH‐EG 6 molecule with the use of BP86/6‐31G* method/basis set provided by Gaussian03. It is found that the observed trend in OH tail group orientation survives and is consistent with a wealth of experimental data available for this type of SAMs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)