The Zn(II) complex of salen-like scaffold [Zn(sal)](H₂O) was synthesized and characterized by elemental analysis, IR, UV–Vis, and ¹H-NMR spectroscopic techniques. The structure of complex was confirmed by single crystal X-ray diffraction studies. In the complex, Zn (II) was placed in the inner N₂O₂ compartment of the salen scaffold in square planar geometry and crystallized in the monoclinic space group P2₁/n. DFT and TDDFT calculations were performed to reproduce the experimentally observed structural and spectroscopic (IR and UV–vis) findings. The bonding of the Zn(II) framework in the [Zn(sal)](H₂O) complex was explored in depth. The theoretical approaches employed were perturbation theory within the context of the natural bond orbital (NBO) framework, and quantum theory of atoms in molecule (QTAIM) and electron localization function (ELF) analysis. The study begins by delineating the difference between the NBO and QTAIM approaches. This paper thus exhibits the supportive nature of NBO theory and QTAIM in discussion of the bonding in the [Zn(sal)](H₂O) complex, when both the methodologies are used in combination.

In the present work, a new Zn(II) perchlorate complex with 2,2’–bipyridyl of formulation {[Zn(bipy)₂(H₂O)](ClO₄)₂} (1) was obtained and well analyzed. This chemosensor was evaluated as a selective sensor for acetone among the several different organic solvents(CH₃OH, EtOH, i–PrOH, i–BuOH, CHCl₃, CH₂Cl₂, CCl₄, C₆H₆, C₇H₈, C₈H₁₀, C₂H₃N, C₃H₇NO, C₄H₈O₂, C₃H₆O₃) in a fluorescence turn–off response in accordance with theoretical calculations. Sensing experiments were performed at ambient temperature which shows the acetone molecule distinctly reduces transfer of energy barrier to complex 1 and hence, produces remarkable luminescent quenching. Also, the weak intermolecular hydrogen–bonding interactions thanks to the presence of various hydrogen bonding donors and acceptors, exist between ligand molecules, which were broken during fluorescence, resulting in quenching. The stoichiometry ratio and association constant were evaluated using Benesi–Hildebrand relation giving 1:1 stoichiometry between complex 1 and acetone. Additionally, DFT results can also explicate the significant response on complex 1 upon addition of acetone. This work is vital in a new loom for the detection of acetone and other ketones.

An organic supramolecular salt hydrate (imidazolium:N-phthalolylglycinate:H₂O; IM⁺-NPG⁻-HYD) has been examined for its charge-transfer (CT) characteristics. Accordingly, IM⁺–NPG⁻–HYD has been characterized thoroughly using various spectroscopic techniques. Combined experimental and quantum chemical studies, along with wave function analysis, were performed to study the non-covalent interactions and their role in CT in the supramolecular salt hydrate. Notably, IM⁺–NPG⁻–HYD crystalizes in two configurations (A and B), both of which are held together via non-covalent interactions to result in a three-dimensional CT supramolecular assembly. The through-space CT occurs from NPG^– (donor) to IM⁺ (acceptor), and this was mediated via non-covalent forces. We demonstrated the role of π–π stacking interactions (mixed-stacking donor-acceptor interactions) in the presence of charge-assisted hydrogen bonds in the regulation of CT properties in the self-assembly of the IM⁺–NPG⁻–HYD salt hydrate.

A Zn(II) perchlorate complex has been prepared and characterized by single X-ray crystallography, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, infrared spectroscopy, elemental analysis, and UV-vis spectroscopy. The complex crystallizes in the monoclinic space group P21/c (Z = 4) with a pentacoordinated zinc center. Interestingly, the Zn complex was found be to a potential fluorophore that could sense acetone and other ketones with high selectivity and sensitivity.