EXPERIMENTAL AND THEORETICAL INVESTIGATION OF AMINOPYRIMIDINE-CARBOXYL(ATE) INTERACTIONS IN TRIMETHOPRIM 1,2-CYCLOHEXANEDICARBOXYLATE

Trimethoprim [2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine], TMP, containing pyrimidine ring play a significant role in many biological systems [l]. The pyrimidine ring system, present in nucleic acids, several vitamins, coenzymes etc., provides potential binding sites for metal ions. Trimethoprim is a well-known biological agent, also employed as a metabolic inhibitor of the dihydrofolic acid reductase enzyme [2] . TMP also showed complexing ability with various carboxylic acids [3]. In the complexes N-H…O hydrogen bonds were established between the pyrimidinic group of trimethoprim and the carboxylate group of some carboxylic acids. Hydrogen bonding is the most important noncovalent interactions. It plays a vital role in biological structure and functions, molecular design [4]. Hydrogen bonded motifs can self-organize in various ways, leading to a variety of supramolecular architectures [5] . In this study, a new trimethoprim-1,2-cyclohexanedicarboxylate salt was synthesized and characterized by analytic and spectroscopic methods. Then, a complete description of the structural properties of the compound through its consistency with the spectroscopic data has been presented by theoretical studies. Structural and energetic properties of the compound have been investigated by Density Functional Theory (B3LYP) with 6-311G(d,p) basis sets [6]. Bond lengths for TMPH+ and TMPH+C8H9O4 -have been given in (Fig 1) Also theoretical calculation provides another method to investigate the important characters of materials. Calculation is an alternative option since it is difficult to directly measure hyperpolarization. The first order-hyperpolarizability and related properties of TMPH+ , C8H9O4 - and TMPH+C8H9O4- were calculated using B3LYP/6-311G(d,p) basis set, based on the finite field approach. The mean first-order hyperpolarizability can be calculated using the following equations. Mean first order hyperpolarizability of TMPH+ , C8H9O4 - and TMPH+C8H9O4- were calculated to be 3.68x10-30 esu 8.64x10-30 esu, 5.55x10-30 esu, respectively.