Experimental and Computational Investigations of Supramolecular Interactions in Cd(II)–Organic Hydrate: Catalytic Applications in the Knoevenagel Condensation Reaction under Solvent-Free Conditions

A dinuclear cadmium(II) complex, [Cd₂(Hhqc)₂(H₂O)₄] (H₃hqc=4,8-dihydroxyquinoline-2-carboxylic acid) was synthesized and characterized by single crystal X-ray diffraction studies, elemental analyses and thermo-gravimetric studies. The metal centers are found to be six coordinated with distorted pentagonal pyramidal geometry around them. The complex shows few significant intermolecular hydrogen bonding interactions to produce a three dimensional supramolecular network comprising of T8(2) water tapes. Besides these non-covalent interactions few other supramolecular interactions are also involved within the molecular dimer like π⋅⋅⋅π stacking, Cd⋅⋅⋅π etc. They have been analyzed using DFT calculations, MEP surface analyses and NCI plot index analyses. The detailed study highlights the complex interplay of π-stacking, H-bonding, and spodium interactions in stabilizing the dimers of complex, which providing precious insights into their energetic and structural characteristics. Further more, the catalytic efficiency of the synthesized complex has been investigated as an effective heterogeneous catalyst in the Knoevenagel condensation reactionunder solvent-free conditions.