Structure/function relationships of a new stannate (IV) complex based on 5,7-dichloro-8-hydroxyquinolinium, accomplished with DFT calculations

Abstract

In this work, a novel compound bis(5,7-dichloro-8-hydroxyquinolinium) hexachlorostannate (II) dihydrate, formulated as (C9H6Cl2NO)2[SnCl6]·2H2O, has been synthesized and characterized by single crystal X-ray diffraction (XRD), Hirshfeld surface analysis, thermal studies, IR and UV-Vis spectroscopies, photoluminescence properties and in vitro biological activities. Stannate complex crystallizes in the triclinic system with space group P1¯. It is built of [SnCl6]2− anions and (C9H6Cl2NO)+ cations in the 1/2 ratio. The crystalline structure is stabilized by intermolecular and intramolecular hydrogen bonds and offset π-π stacking interactions. Intermolecular interactions were investigated by Hirshfeld surfaces. In addition, the optimized molecular structure and vibrational frequencies were calculated by the Density Functional Theory (DFT) method using the B3LYP function with the LanL2DZ basis set. On the basis of the comparison between calculated and experimental results, assignments of the fundamental vibrational modes are discussed. Subsequently, the nucleophilic and electrophilic binding site regions are elucidated using the molecular electrostatic potential (MEP). The thermal behavior was studied by TG-DTG-SDTA analyses. Moreover, the optical properties of the crystal were studied using optical absorption UV-visible and photoluminescence (PL) spectroscopy. To investigate microscopic third order non-linear optical behaviour of the examined complex, the electric dipole μtot, the polarizability αtot and the hyperpolarizability 〈γ〉 were computed using DFT//B3LYP/6-31G(d,p) and DFT//B3LYP/LanL2DZ methods for organic cation and hybrid compound, respectively. According to our calculation, the title compound exhibits non-zero 〈γ〉 value revealing microscopic third order nonlinear optical behaviour. In addition, the antioxidant activities of the complex were also investigated through scavenging effect on DPPH radicals, total antioxidant activity and reducing power.