Density Functional Theory Studies of Temperature and Solvent Effect on Coordination Chemistry of Cu (II)- Trimethoprim Complexes

Abstract

The computational analysis was performed by using density functional theory method to find the effect of temperature and solvent on geometrically different Cu(II)-trimethoprim complexes experimentally synthesized at two different temperatures. The initial geometries of three complexes r1403 (C36H48Cu2N8O14), r1444 (C36H48Cu2N8O14) and r1435 (C36H50Cu3N8O16) were obtained from the crystallographic data. All these geometries along with reactants were optimized at B3LYP/6-31g, B3LYP/LANL2DZ, BLYP/6-31g and BLYP/LANL2DZ level of DFT theories at 298K and 352K. Single point energies were calculated in the gas as well as in the solvent phase. SDD basis set was used to calculate single point energy values in the gas phase whereas SCRF (self-consistent reaction filed) calculations were performed using default (water) and ethanol solvents. The results obtained from computational analysis were compared with the experimental data and it was concluded that r1435 is an intermediate geometry which can be converted into a stable geometry after recrystallization process. Also, more stable and reactive copper (II) trimethoprim complexes can be obtained at 352K temperature with ethanol as a solvent. Moreover, computational analysis also shows that LANL2DZ is more accurate basis set and gives more reliable results as compared to 6-31g basis set with respect to validation of experimental results.