ChemPhotoChem最新文献

Molecular recognition of guest molecules within confined cavities enables effective modulation of their chemical and physical properties through noncovalent interactions. Because these modulated properties reflect the structural features of the host–guest assembly, the guest molecule can serve as a molecular probe to elucidate the origin of the host-induced modulation. Herein, we report the formation of a host–guest complex composed of an emissive Ir(III) complex salt and a resorcin[4]arene host, along with the photophysical modulation of the guest via noncovalent interactions with the host. NMR spectroscopic analysis reveals a 1:1 binding stoichiometry, in contrast to the previously reported 6:1 stoichiometry, because the guest is larger than the cavity of the resorcin[4]arene hydrogen-bonded hexameric capsule. This 1:1 binding mode is unambiguously confirmed by single-crystal X-ray diffraction analysis. The photoluminescent properties of the Ir(III) complex are enhanced in the presence of the host, indicating that electronic communication between the host and the guest plays a crucial role in modulating its photophysical behavior. These findings are further supported by density functional theory calculations. Overall, this article provides new insights into the photophysical dynamics of entrapped emitters and highlights the pivotal role of host–guest interactions in tuning emission properties.

Converting atmospheric nitrogen (N₂) into ammonia (NH₃) by sustainable methods presents a significant challenge in green chemistry. Photocatalytic N₂ fixation under visible light offers a promising solution, provided efficient catalysts can effectively weaken the strong N≡N bond. In this study, we present a composite photocatalyst composed of the metal–organic framework (MOF) UiO-66-NH₂ and substoichiometric tungsten oxide (W₁₈O₄₉). The oxygen vacancies in W₁₈O₄₉ extend its visible light absorption, while UiO-66-NH₂ provides a high surface area and amine-functionalized linkers that enhance light harvesting. We synthesized UiO-66-NH₂/W₁₈O₄₉ composites with varying UiO-66-NH₂ contents (30%, 50%, and 70% by weight) and evaluated their photocatalytic performance under visible-light irradiation. The 50% UiO-66-NH₂/W₁₈O₄₉ composite exhibited the highest NH₃ production rate of 420.8 μmol g⁻¹ h⁻¹, which is 27.2 times higher than that of pure UiO-66-NH₂ and 10.9 times higher than that of W₁₈O₄₉. This enhancement is attributed to the synergistic heterojunction between UiO-66-NH₂ and W₁₈O₄₉, where the MOF provides a large surface area and efficient light absorption, while W₁₈O₄₉ contributes plasmon-generated hot electrons and abundant oxygen vacancies. The composite demonstrates broadened visible-light absorption, efficient charge separation, and rapid charge transfer, thus suppressing electron–hole recombination. These results highlight the potential of the UiO-66-NH₂/W₁₈O₄₉ composite as an effective photocatalyst for solar-driven ammonia production under mild conditions.

In this contribution, a set of five differently substituted phenoxazines (POA) derived from a central terephthalonitrile core is investigated. Depending on incorporated electron-donating groups (-NH₂, -NMe₂, and -OMe) or electron-withdrawing groups (-NO₂ and -CN), distinctive luminescent behavior is observed, with preferred emission either in solution, in the solid-state, or in both. An in-depth assessment of the photophysical properties revealed a subtle influence of the substituents on the absorption and emission wavelengths, which correlate with the Hammett parameters, yet a strong sensitivity to the surrounding environment. Hence, solvatochromic response and aggregation studies were conducted to identify the optimal conditions for efficient emission. Absolute photoluminescence quantum yield values of up to 0.47 in tetrachloromethane and 0.33 in the solid state were determined, underscoring the impressive photophysical characteristics of the presented compounds. X-ray diffractometric analyses in combination with Hirshfeld surface evaluation were employed to elucidate the packing effects and their possible relation to the photophysical performance. Finally, density functional theory calculations provided a detailed understanding of the occurring electronic transitions and spatial localization of the natural transition orbitals.

The photochromic interconversion between spiropyran (SP) and merocyanine (MC) was investigated using density functional theory (DFT) and its linear-response time-dependent extension. Equilibrium and transition-state geometries in both the ground and electronically excited states were optimized using the ωB97X-D3BJ exchange-correlation functional, combined with empirical dispersion corrections, the conductor-like polarizable continuum model for solvation, and the def2-TZVPP triple-ζ basis set. Conical intersection geometries were located using the spin-flip TDDFT approach. Key molecular configurations, including equilibrium, transition-state, and conical intersection geometries, were mapped along the SP–MC interconversion, and the energetically most favorable relaxation pathways were determined. The results also demonstrate that the relaxation pathway through the triplet manifold could be a possible alternative. The influence of the solvent environment on UV–vis absorption, excited-state relaxation, and SP–MC interconversion was emphasized. Finally, the efficiency of the full back-and-forth SP–MC transformation, induced by either light or thermal effects, was characterized in both vacuum and polar environments.

We systematically investigate the electronic structure factors underpinning the distinct photochemical behaviors in a series of structurally related Fe(III)–azido complexes $$ (1), $$ (2), and $$ (3), using density functional theory (DFT), time-dependent DFT, and ab initio ligand field theory together with the angular overlap model. It had been shown in experimental studies that the ground spin state of these complexes influences the photochemical reaction pathways, specifically photoreductive and redox-neutral ligand dissociation, and photooxidation to yield high-valent nitrenoid species. In addition, 3 shows a unique acetato-ligand decarboxylation channel not observed in the low-spin analogs. In this first comparative in silico study of the three complexes, we show how the steric demands of the methylated ligand in 3 lead to a weakened equatorial ligand field resulting in a high spin ground state which in turn influences the excited state manifold. With a simple approach, wherein we explore the evolution of the electronically excited states along specific vibrational modes, we find the onset of dissociative photooxidation paths in 1 and 2 which are absent in the high-spin species 3. Similarly, we can rationalize why photoinduced decarboxylation is only observed in 3.

Herein, we report the design and photo-modulation of full-color circularly polarized luminescence (CPL) of a V-shaped, cyclohexanediamine-derived chiral trans-CCP functionalized with cyanostilbene moieties. With pronounced aggregation-induced emission features and photo-responsiveness, trans-CCP self-assembles in DMSO-H₂O into a blue fluorescent gel constituted by nanospheres. Upon photoirradiation with 365 nm light, the gel undergoes a morphological transition into one-dimensional nanofiber. It is interesting to find that photoinduced transformation is accompanied by an inversion of CD and CPL signals. Furthermore, through coassembly with achiral dye molecules that exhibit emissions ranging from green to red, trans-CCP readily serves as both an efficient chirality and energy transfer donor, rendering the originally achiral dye molecules a series of CPL emitters. Critically, the CPL signals of the doped emitters invert in response to UV irradiation while maintaining excellent color fidelity, following the supramolecular chirality switching of the CCP host. Therefore, a robust, photo-regulated platform for full-color CPL inversion within a coassembled system is established. By harnessing chirality transfer energy migration and photo-switching, this work opens new avenues for the remote control of full-color CPL materials.

Metallophotoredox catalysis is very useful in transforming the chemical moieties for readily available diverse scaffolds. This study presents an efficient and concise methodology devised for decarboxylative oxidation of aliphatic carboxylic acid through manganese (II) acetate-catalyzed visible blue light-induced homolysis. The control experiments showed the presence of peroxide radical along with singlet oxygen suggesting the radical pathway. The light on/off experiment proved that continuous irradiation of light is essential for efficient photocatalytic decarboxylative oxygenation reaction. The established protocol is applicable for both primary and secondary carboxylic acids to afford aldehydes and ketones, respectively, in good yields.

This article presents an in-depth study on the use of tetrazine-based coordination polymers as photocatalysts for the treatment of wastewater contaminated with organic pollutants. The synthesis of a Zn-based MOF incorporating s-tetrazine dicarboxylic acid as an organic ligand is detailed, following a solvothermal method. Analysis of the crystalline structure reveals a three-dimensional porous network characterized by pores approximately 8 Å wide, forming a highly interconnected material. The photocatalytic activity of this material is then investigated for the degradation of ibuprofen under simulated solar irradiation. The reaction mechanism and the intermediate species involved in the degradation pathway are elucidated. This research contributes to a better understanding of tetrazine-based materials in aqueous-phase applications and highlights their potential for sustainable environmental treatment strategies.

In this work, the CuI thin film is introduced as an alternative back contact layer (BCL) to the expensive Au BCL for the Cu₂O photocathodes. It is fabricated by a solution process using CuI precursor solution, dissolving CuI powders in acetonitrile. The thickness of CuI BCL is optimized by controlling the concentration of CuI precursor solution. As a result, the Cu₂O photocathodes based on the CuI BCL with the optimal thickness (approximately 6.4 nm) show a comparable photoelectrochemical performance compared to the Cu₂O photocathodes based on the traditional Au BCL. The solution-processed CuI thin film properly works as a BCL for the Cu₂O photocathodes by allowing the effective hole transport from Cu₂O to the back contact and suppressing the hole–electron recombination at the back contact via the large conduction band offset at the CuI/Cu₂O interface. This provides a novel and promising approach to develop the photocathode with entirely low-cost materials for solar water splitting.

Freshwater pollution is a critical global issue, requiring efficient, eco-friendly treatment technologies. In this study, a new ternary nanocomposite photocatalyst was fabricated by combining silver phosphate (Ag₃PO₄) with platinum nanoparticles (Pt NPs) and polymethyl methacrylate (PMMA), a flexible long-chain polymer. The nanocomposite was prepared using coprecipitation, ultrasonic blending, and light-induced reduction. Structural and chemical analyses confirmed successful integration of all components. (XRD) X-ray Diffraction verified the body-centered-cubic phase of Ag₃PO₄, while X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy evidenced the presence and interaction of Ag₃PO₄, Pt, and PMMA. (TEM) Transmission Electron Microscopy revealed PtNPs (5–15 nm) uniformly anchored to the PMMA-coated Ag₃PO₄ surface, displaying varied morphological features. Optical characterization via UV–vis spectroscopy showed a clear reduction in bandgap, enhancing visible light absorption. The Pt@PMMA/Ag₃PO₄ photocatalyst demonstrated outstanding contaminant removal under visible light, achieving 94.20% breakdown of imidacloprid (IM) insecticide in 60 min and near-total removal of acridine orange (ACO) dye in just 15 min. This enhanced performance is attributed to increased light utilization from Pt, larger reactive surface area, and efficient charge separation and transport facilitated by the polymer network, as evidenced by photocurrent response and reduced photoluminescence. The currently developed Pt@PMMA/Ag₃PO₄ nanocomposite shows strong potential as a high-performance, sustainable photocatalyst for light-driven water purification.