Water‐Encapsulated Ni(II) Salphen‐Type Host Complexes: Experimental and Theoretical Analysis of Potentially Bioactive Quasi‐Isostructural Polymorphs

Abstract

In this study, we report the formation of two quasi-isostructural polymorphs (a and b) of a Ni(II) salphen-type Schiff base complex using solvent evaporation technique. The polymorphs are inclusion compounds with guest water molecules exhibiting similar spectroscopic and thermal characteristics. Single crystal XRD (X-ray Diffraction) analyses reveal the subtle differences in packing and supramolecular interactions which are quantified using Hirshfeld and 2D finger print analyses. Electrostatic potential analysis shows significant difference in potential distribution in the two molecules. The compositional analysis of the frontier orbitals and differences among the atomic charge distribution of the polymorphs are established using DFT (Density Functional Theory) calculations. Apart from highlighting the strength of encapsulation, DFT study substantiates the formation of inclusion compounds through single point energy calculations. Effects of inherent differences in the polymorphs on potential biological activity are probed using in silico molecular docking with B-DNA and Human Serum Albumin (HSA). The a form shows superior bioactivity while b form excels in water encapsulation.[a] Dr.

A modern approach for the sensing of aqueous Al(III) ion by Ni(II) Salen‐type Schiff base complexes

“…The nickel atom is located almost exactly in the same plane of the ligating atoms O3–N2–N1–O1 (0.0015 Å for Ni1 from the N 2 O 2 plane). The Ni(II)–N and Ni(II)–O bond lengths are comparable with similar reported systems 6b, 34. The six‐membered metalochelate ring involving the diimine spacer group (metallocycle #1 N1–C8–C9–C12–N2–Ni1) adopts a twist boat conformation which is evidenced from the puckering analysis with a puckering amplitude of (Q) 0.797(4) °, (ɵ) 88.0(3) °, (ɸ) 89.6(2)° (Figure a).…”

A study of structural effects on linear and nonlinear response of bicompartmental Ni (II) Schiff base complexes

“…This is again confirmed from the bond angle and bond length around the central metal ion: O1 –Ni1–N1 and O2 –Ni1–N2; O –Ni1–O and N –Ni1–N are around 93° and, in the range, 86–85°, respectively. The bond length between the metal and the donor atoms (Ni–O and Ni–N) lies in 1.84–1.85 Å range and it has been noted that Ni–O distance lies in the normal range as reported in similar nickel complexes . But the bond distance between the two azomethine nitrogen atoms (N1 and N2) and the Ni atom is found to be much shorter than that between oxygen donor atoms and the metal center.…”

“…UV–Vis spectra of four square planar salen Ni (II) compounds are observed to be similar in nature and similar to other reported systems . The absorption band below 500 nm having ɛ > 1000 mol −1 dm 3 cm −1 can be assigned to metal–ligand, ligand–metal or intraligand transitions.…”

Nitrato, Pseudohalo‐Linked Zn(II)/Cd(II) Schiff‐Base Complexes with 1,3‐Diimine Spacer Group: Syntheses, Crystal Structures, DFT, TD‐DFT and Fluorescence Studies

“…Globularity (G) and asphericity (Ω) measurements of the surfaces for complex 1 and 2 gave values 0.745, 0.038 and 0.754, 0.052 respectively which suggests that the surfaces deviate from perfect spherical shape almost equally.2D finger print plot analysis have been carried out to quantify the intermolecular interactions/short contacts present in the crystal system. For both the complexes (1‐2) the highest contribution comes from the H⋅⋅⋅H interactions which show the stability of the crystal lattice Figure (d) and 4(h)) . For complex 1 , it has a value of 47.0% with a d i +d e value ca .…”