A new coordination polymer of Cd(II) with 4-methyl-1,2,4-triazole-3-thiol ligand: synthesis, characterization, crystal structure, photoluminescence and DFT calculation

A new Cadmiun(II) coordination polymer, {[Cd(µ-mptrz) 2 ].0.5((CH 3 ) 2 SO)} n was prepared from the reaction of CdBr 2 with 4-methyl-4 H -1,2,4-triazole-3-thiol (Hmptrz) ligand in methanol. The coordination polymer was thoroughly characterized by elemental analysis, IR, UV–Vis, 1 HNMR spectroscopies, and thermogravimetric analysis. Moreover, its structure was studied by the single-crystal diffraction method. Compound 1 has a 1D chain structure. Furthermore, crystal structure is stabilized by intermolecular weak interactions, for example, C–H···O, C–H···N, and C–H···S hydrogen bonds. Besides, the photoluminescence of 1 has been investigated. This compound exhibits photoluminescence with an emission maximum of 321 nm upon excitation at 259 nm. The present work is a combined experimental and computational study. Quantum chemical parameters such as bond lengths, bond angles, HOMO–LUMO energy levels, energy band gap Δ E , chemical hardness η, the dipole moment μ, and Natural bond orbital (NBO) analysis of the compound were investigated using the DFT at M06/GENECP (6-31 g(d) and LANL2DZ) basis sets for compound 1 . Our calculation results have shown that compound 1 has an energy band gap (∆E = 3.857 eV), indicating a high recommendation for a semiconductor compound. The optimized geometry of the Cd(II) coordination polymer is shown in good agreement with single crystal X-ray data. UV/Vis spectra are calculated with the time-dependent density functional theory (TD-DFT) method. Furthermore, TD-DFT displays intraligand transition (ILCT) between triazole bridging ligands. Moreover, NBO analysis of the Cd(II) coordination polymer indicates that the lone pair donor orbital interaction between the N, S, and O lone pairs and π*, σ* anti-bonding orbitals provides stronger stability. Additionally, Solid-state density functional theory (DFT) calculations were performed on 1 using the program VASP to understand the electronic states and conduction pathways of the coordination polymer.