Abstract
The design of new molecular electrocatalysts for Hydrogen Evolution Reaction (HER) is an active area of research. In the present work, we report the synthesis and structural characterization of tetra -coordinated [5,10,15,20-(tetraethyl-4(4-butyryl) oxyphenylporphyrinato)] zinc(II) [Zn(TEBOP)] ( II ) and penta-coordinated (4-cyanopyridine)(meso-tetrakis (ethyl-4 (4-butyryl) oxyphenyl) porphyrinato) zinc(II) [Zn (TEBOP)(4-CNpy)] ( III ) complexes. All compounds, including the parent ligand 5,10,15,20-(tetraethyl-4(4-butyryl)oxyphenylporphyrin (H2TEBOP) ( I ), were fully characterized using multiple analytical, spec-troscopic and electrochemical techniques. Single-crystal X-ray diffraction study revealed stabilization of the structure via multiple non-covalent C-H ...Cg pi inter-molecular interactions. Optical absorption and emission spectroscopy results indicated a noticeable effect of the axial ligands on the photophysical prop-erties. HER study revealed higher activity of complex ( III ) than complex ( II ), possibly due to the presence of an axial ligand (4-cyanopyridine, 4-CNpy) in the former. Both experimental and computational mod-elling results suggested a ligand-centred HER process.(c) 2023 Elsevier B.V. All rights reserved.