- Turkish Computational and Theoretical Chemistry
- Vol: 3 Issue: 1
- The amidine formed by tacrine and saccharin revisited: An ab initio Investigation of Structural, Ele...
The amidine formed by tacrine and saccharin revisited: An ab initio Investigation of Structural, Electronic and Spectroscopic Properties
Authors : Nursel ACAR
Pages : 25-37
Doi:10.33435/tcandtc.486573
View : 8 | Download : 3
Publication Date : 2019-06-15
Article Type : Research
Abstract :Computational study of tacrine and saccharin and their amidine complex (TacSac) was peformed by ab initio calculations including electron correlation. Structure, UV-Vis spectra and charge distribution of the amidine (TacSac) were investigated using ground state geometries optimized at MP2/6-311++G(d,p) level. The effects of solvent was investigated using polarizable continuum model (PCM) in conjunction with the solvation model based on density (SMD) approach. TacSac geometry remained same in gas phase and in H 2 O both with PCM and SMD models in contrast to former DFT results. The amidine is calculated to be stable indicating that former DFT calculations underestimated the stability of the investigated amidine. UV-Vis spectra and electronic transitions were calculated at CIS/6-311++G(d,p), B3LYP/6-311++G(d,p) and CAM-B3LYP/6-311++G(d,p) levels of theory and B3LYP gave the best results. TacSac has a peak at a higher wavelength enabling S 0 →S 1 transition with a lower energy. S 0 →S 1 transition corresponds to full charge transfer between HOMO and LUMO orbitals of TacSac in H 2 O. The ab initio results indicate that the TacSac system can be synthesized with an easy condensation reaction, and that the amidine product is a potential candidate for photochemical charge-transfer systems.Keywords : Amidine, Møller-Plesset, Density Functional Theory, Tacrine, Saccharin