Theoretical Investigation of Linker Effects on New Designed Bodipy-Ferrocene Based Three Channels Calcium (II) Ion Sensors; as Redox, Colorimetric and Fluorescent Properties

Abstract

In this work, the structural, spectroscopic and electronic properties of proposed model complexes of 4,4-Difluoro-4-borata-3a-azonia4a-ana-s-indacene(BODIPY)-Ferrocene based Calcium ion sensors were investigated by means of DFT calculations. Geometric, and electronic effects of 4 different chemical linkers, azin(1), azadiene(2), urea(3) and thiazole(4), were predicted on the development of these fluorescent sensors computationally at B3LYP/LANL2DZ level. Designed sensors are expected to work in living systems, so all the calculations were carried out in water phase. In addition, frontier molecular orbital properties, electronic spectra and electrochemical properties were also computed. According to the computational thermodynamic results, sensors which contain urea and thiazole as the linker group, make the most stable complexes with Ca(II) ion. In general, it was found that calcium complexation of sensors leads to lower absorption energy bands, causes a decrease in HOMO-LUMO gap with respect to the linker type, a bathochromic shift in the lowest energy absorbance wavelengths, and an anodic shift of redox potential. Overall result of complexation is an increase in the absorption λ max value, while solvent effect causes a blue shift in absorption bands. Maximum emission redshift is observed in urea bridged sensors, followed by thiazole. This sequence was also spotted in the acidic environment. Molecular logic gates are also formed for normally protonated sensors and their metal complexes. Each type of designed sensors is corresponded to a certain type of logic gates.