Energetically significant anti-parallel π-stacking and unconventional anion-π interactions in phenanthroline based Ni(II) and Cu(II) coordination compounds: Antiproliferative evaluation and theoretical studies

• Published in: Inorganica Chimica Acta 2021-02, Vol.516, p.120082, Article 120082
• Main Authors: Sharma, Pranay, Sarma, Pinku, Frontera, Antonio, Hussain, Sahid, Verma, Akalesh K., Bhattacharyya, Manjit K.
• Format: Article
• Language: English
• Subjects: Anions; Antiproliferatives; Apoptosis; Chemical analysis; Chloride ions; Clathrates; Coordination compounds; Copper; Crystal lattices; Crystal structure; Cytotoxicity; Enclathration; Infrared analysis; Infrared spectroscopy; Nickel compounds; Self-assembly; Single crystals; Stacking; Structural analysis; Supramolecular host; Surface analysis (chemical); Toxicity; Water chemistry; π-Stacking
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2020.120082

Werner type clathrate of Ni(II) involving guest benzoates and Cu(II) phenanthroline coordination compound involving biologically relevant π-stacking and unconventional anion-π interactions considering cytotoxicity in Dalton’s Lymphoma (DL) malignant cancer cells. [Display omitted] •Phenanthroline based coordination compounds of Ni(II) and Cu(II).•Unconventional enclathration of a single guest water molecule and Benzoates.•MEP surface analysis and DFT calculations.•Anti-parallel π-stacking and Unconventional anion–π interactions.•MTT cell viability and apoptosis assays in Dalton’s Lymphoma cancer cell lines. Two new coordination compounds of Ni(II) and Cu(II), viz. [Ni(phen)2Cl(H2O)] 4-NO2bz·3H2O (1) and [Cu(phen)2Cl]Cl·5H2O (2) (phen = 1,10-phenanthroline, 4-NO2bz = 4-nitrobenzoate) have been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR, electronic spectroscopy, TGA and EPR. The detailed crystal structure analysis of the Werner Type Clathrate 1 reveals the self-assembled unconventional enclathration of 4-NO2bz moieties in supramolecular Ni(II) hosts. In addition to the conventional discrete (H2O)n clusters in the crystal structure of 2, the layered architecture involves enclathration of single guest water molecules in the Cu(II) supramolecular hosts. We have theoretically analysed the biologically relevant anti-parallel π-stacking interactions in compound 1 and two types of anion–π interactions involving coordinated and uncoordinated chloride ions in compound 2. MEP surface analysis and DFT calculations reveal that the anti-parallel π-stacking interaction in 1 is energetically significant and enhanced upon complexation of the ligands to the Ni(II) centre. Remarkably, studies also reveal that in addition to the conventional anion⋯π interaction involving the chloride anion in the lattice, the unusual Cl(chlorido)⋯π interaction observed in the crystal assembly of 2 is also energetically significant. The antiproliferative potential of the compounds 1 and 2 have been studied in Dalton’s Lymphoma (DL) malignant cancer cell lines considering MTT cell viability and apoptosis assays. The compounds 1 and 2 exhibited significant concentration dependent increase in cell cytotoxicity and apoptosis in DL cells with negligible cytotoxicity in normal (PBMC) cells.