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Parameterization of the torsional potential for calix[4]arene‐substituted poly(thiophene)s
Author(s) -
Preat Julien,
RodríguezRopero Francisco,
Torras Juan,
Bertran Oscar,
Zanuy David,
Alemán Carlos
Publication year - 2010
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21463
Subject(s) - thiophene , dihedral angle , ring (chemistry) , molecular dynamics , force field (fiction) , quantum , chemistry , computational chemistry , maxima and minima , molecule , materials science , physics , mathematics , quantum mechanics , organic chemistry , hydrogen bond , mathematical analysis
Three different strategies have been followed to develop the torsional force‐field parameters of the inter‐ring dihedral angles for calix[4]arene‐substituted poly(thiophene)s, a family of highly sensitive ion receptors. These procedures, which are based on the rotational profiles calculated using quantum mechanical methods, differ in the complexity of the model compounds and the processing applied to the quantum mechanical energies before the fitting. The performance of the three sets of developed parameters, which are essentially compatible with the General Amber Force Field, has been evaluated by computing the potential of mean forces for the inter‐ring rotation of 2,2′‐bithiophene, and its substituted analog bearing a calix[4]arene group in different environments. Finally, the ability of the new sets of torsional parameters to describe a calix[4]arene‐substituted poly(thiophene) in tetrahydrofuran solution has been checked using Molecular Dynamics simulations. Specifically, the molecular shape, the polymer conformation, and the effects of the Na + ions trapped in the cavity of the receptor have been examined. Although the potential derived from unsubstituted 2,2′‐bithiophene is able to reproduce the experimental free energies of the minima, the overall results indicate that the parameters derived from the analog bearing a calix[4]arene group provide the best description of the systems under study. This should be attributed to the strong constraints found in complex substituted poly(thiophene)s, which require parameterization strategies able to capture all the interactions and phenomena involved in their inter‐ring rotations. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010