Педагогический журнал Башкортостана №2 2006

2013.  54,  2      –  UDC 541.6:547.12:543.422 SPECTRAL ANALYSIS OF ACETYLCHOLINE HALIDES BY DENSITY FUNCTIONAL THEORY CALCULATIONS M. Karakaya, F. Ucun Department of Physics, Faculty of Arts and Sciences, Sьleyman Demirel University, Isparta Turkey E-mail: mkarakayafizik@hotmail.com Received October, 29, 2011 Revised — April, 8, 2012 The optimized molecular structures, vibrational frequencies and 1H and 13C NMR chemical shifts of acetylcholine halides (F, Cl and Br) have been investigated using density functional theory (B3LYP) method with 6-311G(d) basis set. <...> The comparison of their experimental and calculated IR, R and NMR spectra of the compounds has indicated that the spectra of three optimized minimum energy conformers can simultaneously exist in one experimental spectrum. <...> The calculated optimized geometric parameters (bond lengths and bond angles), vibrational frequencies and NMR chemical shifts for the minimum energy conformers were seen to be in a good agreement with the corresponding experimental data. <...> Within the last decades, choline and acetylcholine derivatives attract many research teams to analyze their vibrational frequencies using various computational levels, including medium and/or large basis sets because of the molecular complexity, the computational costs or hardware performance [ 1—3]. <...> The determination of the minimum energy conformers on the potential energy hypersurface of acetylcholine has been subject by many theoretical works. <...> Theoretical study of acetylcholine bromide has denoted that the experimental gauche-gauche conformation corresponds only to a local energy minimum about 2 kcalmol–1 above the global one associated with a different gauche-gauche conformation [ 12 ]. © Karakaya M., Ucun F., 2013 . 258 – 268   . 2013. . 54,  2 259 As seen from the above discussion the ground state conformation of acetylcholine is labile and influenced by its environment. <...> COMPUTATIONAL DETAILS The optimized structure parameters and vibrational frequencies for acetylcholine halides (AChF, AChCl and AChBr) were calculated by density functional theory (B3LYP) method at 6-311G(d) basis set level. <...> For the 1H and 13C NMR chemical shift calculations both in vacuum and in solvent media of the title compounds the GIAO approach was used. <...> The theoretical chemical shift 1H and 13C values were <...>