Syntheses, characterizations, crystal structures, DFT/TD-DFT, luminescence behaviors and cytotoxic effect of bicompartmental Zn (II)-dicyanamide Schiff base coordination polymers: An approach to apoptosis, autophagy and necrosis type classical cell death

Abstract

Two new Zn (II)-dicyanamide (dca) 1-D chain coordination polymers (CPs), [Zn (L-OMe)(mu(1)-dca)(mu(1,5)-dca)](n) (1) and [Zn (L-OEt)(mu(1)-dca)(mu(1,5)-dca)](n) (2) have been successfully synthesized from bicompartmental Schiff base ligands N,N-'-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane (H2LOMe), N,N-'-Bis(3-ethoxysalicylidenimino)-1,3-diaminoproane (H2LOEt) respectively and structurally characterized using various spectroscopic protocols like H-1 NMR, IR, Raman, UV-Vis, fluorescence as well as elemental analysis, TGA, PXRD and SCXRD studies. X-ray single crystal study revealed that both the complexes have two different geometrical arrangement of Zn metal centres with distorted square pyramidal Zn(2) and trigonal prismatic geometry Zn(1). Ab-initio DFT (Density functional theory) has been executed at B3LYP (Becke, 3-parameter, Lee-Yang-Parr) using DGDVP (Diffuse gradient double valence polarised) basis set to explain FMO (Frontier molecular orbital), TD-DFT (Time-dependent density functional theory) and photovoltaic efficiency in Dye Sensitized Solar Cell (DSSC). Hirshfeld surface (HS) and 2D fingerprint plot analyses are shed more light on the non-covalent supramolecular interactions. The steady state and time-resolved fluorescence measurements have been conducted in DMSO and solid-state. CPs exhibited bi-exponential decay in DMSO as well as solid-state where fluorescence behaviors are mainly intra-ligand (pi -> pi*) in nature with lifetimes in the range (1.11-1.06 ns). In particular, in vitro cytotoxic activities were evaluated towards MCF7 (breast cancer) cell line, MDA-MB-231 (breast carcinoma) cell line and MCF10A (breast epithelial) cell line using MTT assay. CP1 had lower cytotoxic effect against MCF7 (20 mu M), MDA-MB-231 (15 mu M) cell lines in comparison with cisplatin (42.2 +/- 8, 128.2 +/- 7 mu M). CP1 induced classical cell death apoptosis, autophagy and necrosis. Lower IC50 value of CP1 against MDA-MB-231 cell line provide new insights in the development of cancer therapeutics.