ChemPhotoChem最新文献

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.

A synthetic route for a novel rhodamine-based diarylethene (DAE) systems 1 and 2 is reported. The key synthetic steps involve the preparation of 6′- and 7′-bromo rhodamine precursors, their conversion into azide derivatives, and subsequent Huisgen 1,3-dipolar cycloaddition with a perfluorocyclopentene acetylene unit. The target compounds, 1 and 2, isolated in their “closed” rhodamine and “open” DAE forms, are characterized through nuclear magnetic resonance (NMR), infrared, and UV–vis absorption spectroscopies, revealing distinct electronic environments for the triazole moiety in both derivatives. Spectroscopic studies highlight their intense UV–vis absorption with minimal visible-light absorption, supported by theoretical time-dependent density-functional theory (TD-DFT) calculations. Investigation of chemo-switching behavior with trifluoroacetic acid and metal ions in dichloromethane reveals a two-step protonation process involving the triazole and rhodamine moieties, confirmed by UV–vis absorption and NMR spectroscopies. Such a process is reversible upon triethylamine addition. Selectivity tests show strong responses toward Hg²⁺ and Zn²⁺, for compound 1 displaying an additional response with Fe³⁺. Photoswitching experiments and TD-DFT calculations reveal distinct behaviors for compounds 1 and 2. UV irradiation of 1 results in the formation of an unexpected open-spiro rhodamine species, potentially due to photoinduced acid production. In contrast, 2 undergoes a different spectral feature arising from a degraded product with lower-lying transitions.

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.

An efficient access to 6-(γ-ketoalkylsulfonyl)methyl phenanthridines and 6-(arylsulfonyl)methyl phenanthridines has been demonstrated under visible-light photoredox-catalyzed conditions. Exposure of biphenyl vinyl azides to strained 3°-cyclopropanols in the presence of Ru(bpy)₃Cl₂ and SO₂ surrogate DABSO under blue-LED irradiation triggers a cascade radical cyclization to provide entry to the γ-ketosulfones–tethered phenanthridines in moderate to good yields. On the other hand, entry to the 6-(arylsulfonyl)methyl phenanthridines is demonstrated via a complementary cascade radical cyclization event involving biphenyl vinyl azides and thianthrenium salts in the presence of Na₂S₂O₅ and fac-Ir(ppy)₃ catalyst under blue-LED irradiation. The efficiency of the developed reactions has been established through broad substrate-scope studies, and the mechanistic proposal is backed by incisive mechanistic probing studies.

Metastable-state photoacid (mPAH) has become a common tool for controlling and driving chemical processes with light. mPAHs with fast reverse reactions are desirable for precise temporal control or generating quick pulses of proton concentration. In this work, different approaches towards fast reversing mPAHs are studied. Experimental and computational results showed that stabilizing the charge–transfer intermediate is an effective way to increase the rate. A novel mPAH with a reverse reaction ≈500 times faster than the most used mPAH in methanol is developed. Another water-soluble mPAH showed a reverse reaction with a rate constant of 7.8 s⁻¹, which is the fastest ever reported. The half-life of the acidic state is calculated to be 89 ms, which allowed to demonstrate sub-second switching using this mPAH.