Daya Shankar Pandey

Efficient artificial light‐harvesting systems (ALH) involving energy transfer via FRET in an aqueous environment has been reported. Hydrazone ligands L1 − L3 and ‐BF ₂ complexes (BODIHYs; B1−B3 ) derived from these have been synthesized and meticulously characterized by various techniques like ¹ H, ¹³ C, ¹¹ B, ¹⁹ F NMR, ESI–MS, UV–vis, fluorescence spectroscopy, and structures of B1 and B2 unequivocally determined by X−ray single crystal analyses. Applicability of the B1−B3 have been examined as a LHS platform and categorically shown that these in combination with rhodamine B (RhB) display efficient light harvesting activity under aqueous conditions via aggregation−induced emission (AIE). Calculated energy transfer efficiency and antenna effect for the BODIHYs are significantly high ( B1 = 22%, 5.04; B2 = 18%, 4.07) at a donor/acceptor ratio of 23:1. Furthermore, hypsochromic shift shown by B1 and B2 after grinding completely reverses upon exposure to dichloromethane vapors. Powder X−ray diffraction (PXRD) analyses before and after grinding revealed that the external forces modify crystal packing by disrupting weak intra− and intermolecular interactions within the molecules.

Ammonia (NH₃) is vital in agriculture and industry, yet its large-scale production remains energy-intensive and environmentally hostile. Herein, for the first time we report the development of lead-free nontoxic hexagonal methylammonium iodobismuthate metal halide perovskite (MABI) as a highly efficient and sustainable electrocatalyst for green ammonia production from nitrate reduction. The unique structure of MABI, featuring an isolated BiI₆ octahedron stabilized by a methylammonium cation, offers a highly tunable electronic environment required for nitrogen activation and hydrogenation. The experimental and computational studies categorically established the formation of an interconnected pure hexagonal structure with a band gap of ∼2.1 eV. Electrocatalytic nitrate reduction revealed that MABI displays a remarkable ammonia yield (27.53 μg mg^-1 h^-1) with excellent stability and a quite impressive Faradaic efficiency (40%). This work highlights the potential of halide bismuthate perovskites as an alternative to traditional catalysts to produce ammonia in ambient conditions that address the dual challenges of energy efficiency and environmental sustainability.

New D-A-type catalysts based on Cu (II) complexes (C1 and C2) including dipyrrin ligands with phenothiazine/carbazole as the meso-substituent have been described. The complexes have been thoroughly characterized by various methods (¹H, ¹³C, ESI-MS, EPR, and UV-vis studies), and structures of both C1 and C2 unequivocally determined by X-ray single crystal analyses. The catalysts C1 and C2 are stable at room temperature and exhibit Faradaic efficiency values of ∼56% (C1) and ∼46% (C2) toward homogeneous reduction of CO₂ to CO. The release of CO has been validated by gas chromatographic (GC) studies. Electron-rich phenothiazine and carbazole included in the catalysts facilitate proton transfer, enabling rapid and selective formation of CO over H₂ with FE_H2 values of ∼22% for C1 and ∼7% for C2 and turnover numbers (TON) of ∼46 for C1 and ∼21 for C2. Furthermore, the formation of formate ions has been affirmed by ion chromatography (C1, ∼16%; C2, ∼18%). Detailed electrochemical studies and product analyses suggested that C1 displays superior catalytic activity relative to C2 which has been further supported by theoretical studies.

Two polymorphs of titania were synthesized by varying the reaction conditions. Enhanced HER in rutile nanorods was seen compared to that in anatase granules due to enhanced charge separation and faster diffusion of charge.

We report a series of push-pull type quinolone–quinazoline conjugates (Q1–Q3) exhibiting aggregation-induced emission, solvent polarity/viscosity dependent emissions, and reversible acid/base induced “ON–OFF–ON” type signaling.

The strategic design, synthesis, and thorough characterizations of a redox-active BODIPY-based tripodal system (tri-BDP) displaying efficient aggregation-induced emission (AIE), great sensitivity toward the viscosity of a medium, ability for triplet photosensitization, singlet oxygen generation, and photooxidation have been described. The photophysical properties of tri-BDP in various solvents and in the solid state have been extensively investigated. It displayed efficient AIE and green (∼520) emission in acetonitrile/ether mixture and red (∼621 nm) emission in the solid state. Detailed viscosity-dependent studies suggested that it can act as a fluorescent molecular rotor. Triplet photosensitization, singlet oxygen generation, and photooxidation studies in the presence of 1,3-diphenylisobenzofuran and 1,5-dihydroxyl naphthalene suggested its high efficiency toward intersystem crossing and singlet oxygen generation. Detailed electrochemical investigations suggested the redox activity of the system. Hence, this system represents multifunctional features and can be applied as a functional material for various applications.

A pyrazole appended BODIPY ligand (L) is synthesized and thoroughly characterized by various spectroscopic studies (¹H, [ ]C, [ ]B, [ ]F, ESI–MS, UV-vis and fluorescence). The ligand (L) displays aggregation induced emission (AIE) in solution (a mixture of CH₃OH and water) and solid state. The vital role of the restriction of intramolecular rotation (RIR) in AIE is supported by viscosity experiments and fluorescence lifetime studies. Photophysical behaviour and aggregate morphology is investigated by UV-vis, emission and scanning electron microscopy (SEM). Multiple strong intermolecular hydrogen bonds (C–H[ ]N and C–H[ ]F) play a significant role in the AIE response. In addition, L shows strong sensitivity toward Hg[ ]ion via chelation induced enhanced fluorescence (CHEF) mechanism. Job’s plot analysis suggested a 1:1 binding stoichiometry between L and Hg[ ], which has been further supported by electrospray ionization mass spectrometry and density functional theory.