An experimental and theoretical exploration of supramolecular interactions and photoresponse properties of two Ni(ii) complexes

Abstract

Two new nickel(II) complexes, C₃₂H₂N₈NiClO₉ (1) and C₃₆H₂₈N₁₂NiOF₂₄P₄ (2), have been synthesized where both 2,4,6-tri(pyridin-2-yl)-1,3,5-s-triazine and dipicolinic acid act as tridentate ligands for complex 1 and only 2,4,6-tri(pyridin-2-yl)-1,3,5-s-triazine is employed as a tridentate ligand for complex 2. These complexes were characterized by FT-IR spectroscopy and single-crystal X-ray diffraction. The noncovalent interactions occurring in the crystal packing of both the complexes have been well-defined focusing on π⋯π (for complex 1) and anion⋯π (for complex 2) interactions, which have also been analysed using DFT calculations. Besides, noncovalent interactions such as C–H⋯π, lone pair⋯π, π⋯π⁺, anion⋯π⁺, and π⁺⋯π⁺ along with hydrogen bonding interactions play an important role in the stabilization of both the complexes in a solid state. We also observed that the change in auxiliary ligands exhibits significant variations in their structures, band gaps and photoresponse properties. To gain insights into the charge transport mechanism, several Schottky barrier diode (SBD) parameters like carrier mobility, transit time, carrier concentration, diffusion coefficient, diffusion length, and ideality factor were measured in the light of thermionic emission and SCLC (space charge limiting current) theory.