caa a22 4500 46323975X CHVBK 20180405153309.0 cr unu---uuuuu 170326e20070101xx s 000 0 eng 10.1007/s10947-007-0150-5 doi (NATIONALLICENCE)springer-10.1007/s10947-007-0150-5 Quantum-chemical study of the effects of noncovalent interactions on the nuclear magnetic screening constants of pyrimidine base associates [Elektronische Daten] [A. Nafikova, R. Aminova, A. Aganov, V. Reznik] The effects of weak noncovalent interactions on the nuclear magnetic screening (NMS) constants (σ 1H), (σ 13C) and charge distribution (q t ) on atoms in van der Waals model associates of unsubstituted and substituted pyrimidines and substituted uracil are considered. The NMS constants were calculated by the UB3LYP/6-31G(d,p) with GIAO functions. The correlation dependences of the 1H and 13C σ constants on the charge q on atoms whre constructed. It were shown that they can be represented as polynomials that include the terms that are linear and quadratic relative to the charge. The relations obtained in this way are similar in form and close in magnitude to the coefficients of the known Buckingham and Augspurger functions that describe the electric field effects on the nuclear magnetic screening constants. It was found that the coefficients in these polynomials have a definite physical sense in that they characterize nuclear magnetic screening and the "screening polarizability” tensor in the unperturbed molecule and associate, respectively. The NMS constants and charge distribution in pyrimidine base associates and accordingly the coefficients that reflect their values in polynomials depend on the form, size, and composition of the associate and can vary significantly depending on the position of the pyrimidine base in the associate. Springer Science+Business Media, Inc., 2007 nuclear magnetic screening nationallicence van der Waals associates nationallicence pyrimidine bases nationallicence quantum-chemical calculations nationallicence screening polarizability nationallicence stacking interactions nationallicence electric fields nationallicence charge distribution nationallicence Nafikova A. Kazan State University, Kazan aut Aminova R. Kazan State University, Kazan aut Aganov A. Kazan State University, Kazan aut Reznik V. A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, Kazan aut Journal of Structural Chemistry Springer US 48(2007-01-01), S64-S78 0022-4766 48<S64 2007 48 10947 https://doi.org/10.1007/s10947-007-0150-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10947-007-0150-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nafikova A. Kazan State University, Kazan aut NATIONALLICENCE 700 1- Aminova R. Kazan State University, Kazan aut NATIONALLICENCE 700 1- Aganov A. Kazan State University, Kazan aut NATIONALLICENCE 700 1- Reznik V. A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, Kazan aut NATIONALLICENCE 773 0- Journal of Structural Chemistry Springer US 48(2007-01-01), S64-S78 0022-4766 48<S64 2007 48 10947 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer