Atypical calcium coordination number: Physicochemical study, cytotoxicity, DFT calculations and in silico pharmacokinetic characteristics of calcium caffeates

Two complexes of calcium ions containing monodeprotonated caffeate ligands were synthesized and physicochemically (IR, FIR, NMR, thermal analysis) and theoretically (DFT and pharmacokinetical parameters) characterized. [Ca(C9H7O4)2] · 2H2O 1a and [Ca(C9H7O4)2] · 2H2O KNO31b are compounds with unusual four coordinate calcium ion containing the ligand coordinated to the metal ion through two carboxylic groups arranged with tetrahedrally-like mode (CaO4). Two water molecules are outside the first coordination sphere bound non-equivalently to the ligand through a net of hydrogen bonding. The compounds were found to be cytotoxically inactive. Finally, in silico parameters predict the potential application of the compound as a supplement and/or drug.