The manuscript reports the green-chemical synthesis of a new diindole-substituted benzimidazole compound, B1 through a straightforward route in coupling between indolyl-3-carboxaldehyde and o-phenylenediamine in water medium under the aerobic condition at 75 ºC. The single crystal X-ray structural analysis of B1 suggests that the disubstituted benzimidazole compound crystallizes in a monoclinic system and the indole groups exist in a perpendicular fashion with respect to benzimidazole moiety. The SARS-CoV-2 screening activity has been studied against 1 × 10e4 VeroE6 cells in a dose-dependent manner following Hoechst 33342 and nucleocapsid staining activity with respect to remdesivir. The compound exhibits 92.4% cell viability for 30 h and 35.1% inhibition against VeroE6 cells at non-cytotoxic concentration. Molecular docking studies predict high binding propensities of B1 with the main protease (M^pro) and non-structural (nsp2 and nsp7-nsp8) proteins of SARS-CoV-2 through a number of non-covalent interactions. Molecular dynamics (MD) simulation analysis for 100 ns confirms the formation of stable conformations of B1-docked proteins with significant changes of binding energy, attributing the potential inhibition properties of the synthetic benzimidazole scaffold against SARS-CoV-2. Communicated by Ramaswamy H. Sarma

Under the gravity of future socio-economic development, the viability of water electrolysis still hinges on the accessibility of stable earth-abundant electrocatalysts and net energy efficiency. This work emphasizes the design and synthesis of two newly developed cobalt(II) complexes, [Co(HL)₂(NCS)₂] (Co^mono) and [Co₂(L)₃(CH₃OH)]ClO₄ (Co^di), with a (N,O)-donor ligand, HL (2-methoxy-6-(((2-methoxyphenyl)imino)methyl)phenol). The study delves into understanding their structural, morphological, magnetic, and charge transport characteristics. Moreover, the study explores the potential of these complexes in catalyzing hydrogen production through heterogeneous electrocatalysis. The X-ray crystal structure of Co^mono reveals the octahedral geometry of the Co(II) ion, adopting two HL units and two NCS⁻ units. The Co^di complex exhibits a doubly-phenoxo-O-bridged (μ_1,1) dinuclear complex, forming a typical octahedral geometry for both the Co(II) centres in coupling with three units of L⁻. Temperature-dependent magnetic susceptibility measurements showed that all of the Co(II) ion in Co^mono shows a typical paramagnetic behaviour for high spin octahedral Co(II) ions while the Co(II) centres in Co^di are coupled with doubly-phenoxo-bridges bearing weak ferromagnetic characteristics at low temperature. Electron transport properties of the Co(II) complex-mediated Schottky device address the superior carrier mobility (μ) for Co^di (9.21 × 10⁻⁵) over Co^mono (2.02 × 10⁻⁵ m² v⁻¹ s⁻¹) with respective transit times of 1.70 × 10⁻⁹ and 7.77 × 10⁻⁹ s. Additionally, electron impedance spectral analysis supports the lower electrical transport resistance of Co^di relative to Co^mono. The heterogeneous electrocatalytic HER activity of Co^di and Co^mono in 0.1 M KOH shows excellent electrocatalytic efficiency in terms of the various electrochemical parameters. Constant potential electrolysis, multi-cycle CVs, and post-HER analysis reveal the pre-catalytic nature of the complexes, which in turn delivers Co₃O₄ nanoparticles as the active catalysts for efficient hydrogen evolution.