Unconventional Dual Donor-Acceptor Topologies of Aromatic Rings in Amine-Based Polymeric Tetrahedral Zn(II) Compounds Involving Unusual Non-Covalent Contacts: Antiproliferative Evaluation and Theoretical Studies

Abstract

Two Zn(II) coordination polymers, viz., [Zn2Cl2(H2O)2(µ-4-AmBz)2]n (1) and [ZnCl2(µ-3-AmPy)2]n (2) (4-AmBz = 4-aminobenzoate, 3-AmPy = 3-aminopyridine) have been prepared at room temperature and characterized using elemental analysis, FT-IR, electronic spectroscopy, TGA (thermogravimetric analysis) and single crystal XRD. Crystal structure analyses of the polymers unfold the presence of non-covalent anion–π, π-stacking and unusual NH2(amino)⋯π interactions which provide rigidity to the crystal structures. Unconventional Type I Cl⋯Cl interactions also play a pivotal role in the stability of compound 1. Molecular electrostatic potential (MEP) surface analysis reveals that the MEP values over the center of the aromatic rings of coordinated 4-AmBz and 3-AmPy moieties are positive on one side and negative on the other side which confirms the dual non-covalent donor-acceptor topologies of the aromatic rings and explains the concurrent formation of unusual non-covalent NH2···π and anion–π interactions. DFT (density functional theory) calculations, QTAIM (quantum theory of atoms in molecules) and NCI plot (non-covalent index) index analyses reveal that among various non-covalent contacts involved in the crystal packing of the compounds, H-bonds in compound 1 and π-interactions (NH2···π, π-π, anion–π) in compound 2 are energetically significant. We have explored in vitro cytotoxic potential of the compounds in Dalton’s lymphoma (DL) cancer cells using trypan blue and apoptosis assays. The studies show that compounds 1 and 2 can significantly exhibit cytotoxicity in DL cells with minimum cytotoxicity in healthy PBMC cells. Molecular docking studies reveal that the compounds effectively bind with the antiapoptotic target proteins; thereby establishing a structure activity relationship of the compounds.

Investigation of protein/DNA binding, and in vitro cytotoxicity of novel Cu(ii) and Zn(ii)-dipyrazinyl pyridine complexes

“…This assay helps to determine the viability of cancer cells after exposure to the synthesised complexes and can provide valuable information regarding their potential as anticancer agents. 75 It is based on selectively staining and distinguishing live and dead cells using trypan blue dye. Trypan blue is a blue dye that cannot permeate inside live cells (viable) due to the presence of intact cell membranes that act as barriers to large molecules like trypan blue.…”

L-proline.H2SO4 catalyzed synthesis of novel coumarin-based spiroindolino-3,4-dihydropyrimidin-2(1H)-ones: In-vitro cytotoxic assays and molecular docking study

“…Besides being cost-effective and user-friendly, the method that can be applied to various cell lines, making it a valuable tool for assessing the effects of anticancer compounds. By staining and counting viable and non-viable cells, it is possible to quantitatively measure cytotoxicity and detect early stages of cell death [50]. This assay relies on the differential uptake of the dye Trypan blue by live and dead cells.…”

The Unconventional Noncovalent Interactions Control: Crystallographic and Theoretical Analyses of the Crystalline Structure of 1,1′‐(1‐Chloro‐4‐methoxyphenyl)dibenzene as a Case Study

“…The X⋅⋅⋅X interactions have been classified based on the R−X ⋅⋅⋅X’ (θ1) and R−X’⋅⋅⋅X (θ2) angles, where classical hydrogen bonding (Type II) shows θ1≈180° with θ2≈90°, whereas if θ1≈θ2 the interaction is called of Type I. In case of Cl, despite their weak strength, type I Cl⋅⋅⋅Cl contacts are known to be involved in the packing and properties of several molecular crystals [31–33] …”