Mn(II) complexes of 1-(4-methoxybenzoyl)-4-phenyl-3-thiosemicarbazide containing o-phenanthroline and 2,2-bipyridine as co-ligands: Synthesis, crystal structure, spectral characterization, photoluminescence and electrochemical studies

Here, two complexes [Mn(Hmpth)2(bpy)] (1) and [Mn(Hmpth)2(o-phen)](2) with 1-(4-methoxybenzoyl)-4-phenyl-3-thiosemicarbazide (H2mpth) have been synthesized which contains 2-2'-bipyridine (bpy)/ o- phenanthroline ( o-phen) as co-ligand. The ligand, H2mpth and its Mn(II) complexes have been charac-terized by IR, NMR, magnetic behaviour and single crystal X-ray data. In both complexes, the metal ions adopt a distorted octahedral geometry. Here, role of co-ligands (2,2-bpy and o-phen) on the optoelec-tronic properties of Mn(II) complexes is investigated for the first time. Complex 1 exhibits high fluores-cence intensity as compared to ligand H2mpth and complex 2. The order of fluorescent behaviour found as complex 1 > complex 2 > H2mpth. Thermal behaviour of complexes were also studied. The electro-chemical characteristics of Mn(II) complexes is studied using cyclic voltammetry technique after immobi-lizing it on the glassy carbon electrode modified with Nafion-multi-walled carbon nanotubes. The cyclic voltammetry studies indicate a reversible one electron transfer process corresponding to the Mn2 + /3 + re-dox processes.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Two complexes [Mn(Hmpth)2(bpy)] (1) and [Mn(Hmpth)2(o-phen)](2) with 1-(4-methoxybenzoyl)-4-phenyl-3-thiosemicarbazide (H2mpth) as ligand and 2-2'-bipyridine (bpy) or o-phenanthroline (o-phen) as co-ligand were synthesized and characterized. The optoelectronic properties of Mn(II) complexes were investigated for the first time, showing that complex 1 has higher fluorescence intensity than H2mpth and complex 2. The thermal behavior and electrochemical characteristics of the complexes were also studied. Cyclic voltammetry analysis revealed a reversible one electron transfer process for the Mn2+/3+ redox processes.