Inorganics

Vapor-responsive luminescent materials are desirable for visual detection and indication, yet reversible switching in Cu(I) complexes remains challenging. Here, a series of ionic and neutral Cu(I)–Imphens–diphosphine complexes were designed and synthesized, and their luminescence response to NH₃ and HCl vapors was examined. The complexes were characterized by IR, NMR, X-ray single-crystal diffraction, and ESI-MS. Photophysical studies revealed that absorption and emission are governed by both ligand deprotonation and solvent effects: in dichloromethane, ionic and neutral complexes show markedly different spectral profiles, whereas in DMSO, strong solvation and hydrogen-bond acceptance smooth the spectral differences between ionic and neutral complexes. Notably, when deposited on silica gel TLC plates, complexes 1a and 1b display reversible, visually detectable luminescence switching upon alternating exposure to NH₃ and HCl vapors, suggesting their potential as visual indicators. This response is tentatively attributed to reversible protonation/deprotonation, which modulates high-frequency vibrational quenching channels and the extent of π-conjugation, with additional influence from the confined, highly solvated silica gel microenvironment. These preliminary observations provide a useful basis for the further exploration of Cu(I)-based materials for reversible acid–base vapor luminescent indication.

1,3-di(2-pyridyl)benzene (dpybH) is a fascinating pro-ligand which is structurally similar to terpyridine but the central N atom is replaced by a CH moiety; when CH deprotonation occurs upon binding to a metal atom, then a cyclometallated compound is formed in which the N^C^N-bound ligand is isoelectronic with terpyridine, but it is an anionic ligand rather than a neutral ligand. In this study we prepared and thoroughly characterized two new pro-ligands, namely 1,3-bis(4-triphenylethylene-pyridin-2-yl)-4,6-difluoro-benzene and 1,3-bis(4-tetraphenylethylene-pyridin-2-yl)-4,6-difluoro-benzene, which open the doors for new N^C^N metal complexes. The related platinum(II) complexes, characterized by a weak emission in solution, were also synthesized.

The development of efficient photocatalysts for the degradation of persistent organic pollutants in wastewater remains an important challenge. In this work, Bi₂O₃/TiO₂ heterostructured catalysts with nanotubular morphology were successfully synthesized through a hydrothermal method followed by wet impregnation, and their photocatalytic activity was evaluated for methyl orange (MO) degradation under UV irradiation. Structural, morphological, surface feature, and optical properties were systematically investigated by XRD, Raman, FTIR, XPS, SEM, HRTEM-EDS, N₂ physisorption, and UV–Vis DRS analyses. Rietveld refinement confirmed the existence of oxygen defects in bismuth oxides and their concentration increased with bismuth content. The incorporation of defective Bi₂O₃ with TiO₂ nanotubes induced bandgap narrowing and interfacial electronic interactions. Among the synthesized Bi₂O₃/TiO₂ materials, BTI500-20 exhibited the highest photocatalytic activity, achieving complete MO removal with the highest apparent kinetic constant. Reactive species trapping experiments indicated that photogenerated holes and hydroxyl radicals were the main oxidative species involved in the degradation process. High-performance liquid chromatography (HPLC) analysis revealed the progressive degradation pathway of MO through azo bond cleavage, formation of aromatic intermediates, and subsequent generation of low-molecular-weight oxidation products. The enhanced photocatalytic performance was attributed to the defective structure and synergistic effect of the Bi₂O₃/TiO₂ heterojunction, which promoted interfacial charge separation and facilitated the generation of reactive oxidative species.