ChemPhotoChem最新文献

Carbon nitrides have emerged as promising supports for catalytically active metals in various chemical reactions. Among these, the selective oxidation of benzene to phenol stands out as particularly challenging within the chemical industry due to its traditionally low yields and complex reaction pathways. In our current investigation, we have focused on the synthesis of ionic carbon nitride fragments via a straightforward alkaline hydrolysis method. These fragments demonstrate a remarkable ability to stabilize iron cations within the carbon nitride structure (Frag-Fe), resulting in a highly efficient photocatalyst for benzene oxidation. Employing hydrogen peroxide as the oxidant in a single-step reaction, we achieved an impressive 47 % yield of phenol using Frag-Fe at 12 hours, with negligible production of CO₂ as a byproduct. This compelling outcome underscores the effectiveness of our alkaline synthesis approach in generating carbon nitride-based photocatalysts with exceptional activity for C−H oxidation reactions. Our findings not only contribute to the advancement of carbon nitride-based catalysis, but also hold significant promise for the development of more sustainable and efficient chemical processes in the future.

Industrialisation has led to unprecedented levels of outdoor air pollution, posing a significant health risk to human beings. Consequently, there is an urgent need to replace fossil fuels with sustainable energy sources, thereby mitigating these risks and providing a safer outdoor and indoor environment. Titanium dioxide is a versatile transition metal oxide with applications ranging from energy conversion to environmental remediation. However, it faces limitations, particularly in its absorption spectrum and charge separation efficiency, and enhancing these properties remains a significant challenge. In this research work, we have decorated the surface of TiO₂ hybridising it with noble-metal and/or noble-metal oxides (Ag and/or CuO) to improve the photocatalytic performances (monitoring the removal of nitrogen oxides and benzene, and hydrogen generation from water splitting) under simulated solar-light irradiation. Our results showed that titania modified with an Ag : Cu molar ratio equal to 1 : 1, not only exhibited the most promising performance in terms of nitrogen oxides and benzene removal, it was the optimum amount for the light-induced generation of hydrogen from water splitting.

The development of multifunctional nanosystems for photo-induced hyperthermia and photodynamic effect is a challenging topic in the research of advanced materials for application in biomedical field. Here, we report red-luminescent carbon-nanodots (CDs-PNM/PTC) derived from entrapment of pentacene (PTC) in nanodots prepared from poly(N-isopropylacrylamide) polymer (CDs-PNM) by an easy and reagent-free method. The CD-PNM/PTC nanosystem was characterized by different techniques (UV-Vis spectrophotometry, fluorescence, NMR, AFM). Molecular modelling investigations were performed to unveil stability, structures and energy of the CD-PNM/PTC supramolecular adducts at 298 K and 315 K. The nanosized CDs-PNM/PTC exhibited excellent water-dispersibility, good photothermal conversion efficiency and photosensitizing effect at 680 nm. No significant toxicity and eukaryotic cell uptake are features that open to potential applications in photothermal-photodynamic treatments.

The Front Cover illustrates the sequential one-electron oxidations of corannulene-extended tetrathiafulvalene and the accompanying color changes. Clar sextets for each redox state are highlighted by filled circles within the structures. The dication seems to exhibit some diradicaloid character in line with the fact that four favorable Clar sextets can be drawn for the diradicaloid resonance structure and only two for the quinoid structure. More information can be found in the Research Article by Mogens Brøndsted Nielsen and co-workers (DOI 10.1002/cptc.202400122).

In this work, melem-based supramolecular assemblies were obtained in one step by thermal treatment of melamine in an autoclave in the presence of sodium chloride. The detailed analysis showed that the obtained powder consists of two phases: poorly crystalline Na-PHI flakes and rod-shaped melem hydrate single crystals (several micrometers long and ~300–500 nm wide). Melem hydrate crystals absorb light in the visible range (Eg=2.7 eV) and demonstrate photocatalytic activity in the reaction of partial oxidation of benzyl alcohol to benzaldehyde by air under visible light with high selectivity for the target product. At 60 % conversion of benzyl alcohol, the selectivity of benzaldehyde formation is above 95 %.

Bi₂O₂CO₃ is a typical bismuth-based semiconductor photocatalyst that has attracted much attention because of layered structure and polarization characteristics. However, the wide bandgap of Bi₂O₂CO₃ limits its practical applications in photocatalysis. In this study, the nickel (II)-doped Bi₂O₂CO₃ (Ni²⁺-Bi₂O₂CO₃) with oxygen vacancies was prepared by adding a controllable amount of nickel ions. The photocatalytic efficiency of the optimized sample for ppb-grade NO under visible light irradiation is 59.4 %, which is 2.8 times than that of its counterpart, Bi₂O₂CO₃ (21.2 %). Based on experiments and characterizations, Introduction of nickel ions and oxygen vacancies improves the photocatalytic performance of Ni²⁺-Bi₂O₂CO₃, which not only lowered the bandgap from 3.25 eV to 2.92 eV, but also reduced the recombination of photogenerated carriers by formation of the impurity level. Furthermore, the adsorption and photocatalytic conversion pathway of NO was explored by in situ DRIFTS, the principal byproducts of photocatalytic oxidation of NO are NO₃⁻ and NO₂⁻. This work offers a new perspective to improve the photocatalytic activity by doping mothed for air purification.

During the last decade, thermally activated delayed fluorescence has been the topic of intense research due to its great potential for highly efficient all organic light emitting devices. While the quinazoline heterocycle has been used for its electron withdrawing ability in various push-pull dyes, quinazoline derivatives have been rarely considered for TADF emitters. Here we design and synthesize a new series of dyes with phenyl- or methoxy-substituted quinazoline rings combined with 9,9-dimethylacridan, phenoxazine or phenothiazine and either 1,4-phenylene or 2,5-thienylene as linker. Combining optical spectroscopy and theoretical investigations, we demonstrate that delayed fluorescence is observed in the solid state for the phenyl-substituted quinazoline derivatives for which both quasi-equatorial and quasi-axial conformations are predicted to coexist. Calculations further suggest that the reversed intersystem crossing is likely to involve the second triplet state that shows small energy splitting with the first singlet state. These results prompt further investigations of phenyl-substituted quinazoline based dyes for TADF.

Here we report the synthesis and luminescent properties of the modified polyhedral oligomeric silsesquioxane (POSS) that possesses two types of luminophores, cyanobenzene and N,N-diethylaniline for inducing significant emission not only from each dye but also from molecular interactions on the POSS core. From the optical measurements in the diluted solution, we observed both locally-excited emission and excimer emission originating from intramolecular interactions assisted by POSS. Moreover, highly-efficient exciplex emission was observed from the thin film, indicating that the interaction between luminophores easily occurs in the solid state by accumulating two kinds of molecules in the single POSS molecule. Finally, we also found that the modified POSS showed a unique acid responsiveness which can be caused by protonation at two types of amino moieties. In this manuscript, it is shown that POSS is able to play various roles at the same time: recruiting excited molecules to form exciplexes, suppressing concentration quenching in the solid state, and imparting stimulus responsiveness to exciplexes.

Here we report the design, synthesis, and photoresponsive behavior of supramolecular liquid crystalline (LC) materials based on benzenetricarboxamide and di-ortho substituted azobenzene. Differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray scattering studies confirm the formation of columnar tetragonal mesophase at room-temperature. Photoisomerization studies reveal the visible light responsiveness of compounds in solution. Furthermore, we demonstrate supramolecular gel formation, which undergoes irreversible gel-sol transformation upon blue light irradiation, highlighting its potential for light-triggered applications in the field of drug delivery, energy storage etc.

Visible-light induced selective arylation of 2-imino-2H-chromene-3-carbonitriles and decarboxylative ipso-arylation of coumarin-3-carboxylic acids have been accomplished under mild conditions in the absence of either base or acid and oxidant. By employing blue LEDs as an excitation source, the aryl radicals are generated by Ru(II) complex through a single-electron transfer process, which subsequently react with 2-imino-2H-chromene-3-carbonitriles and 2-oxo-2H-chromene-3-carboxylic acids to produce the desired products. This is the first report on selective arylation of conjugated systems without using either an acid or a base.