ChemPhotoChem最新文献

The Front Cover illustrates the improvement on stability as well as on thermally activated delayed fluorescence (TADF) characteristics, such as lifetime and efficiency, obtained by modifying the core of the organic emitters. The properties of TADF dyes are enhanced going from 9,9-dimethyl-fluorene to the more bulky 9,9’-spirobifluorene. Very long delayed fluorescence has been detected in both dyes as thin films and crystals, where the bulky core is pivotal to reduce deactivating intermolecular pathways. More information can be found in the Research Article by Fabio Rizzo and co-workers (DOI: 10.1002/cptc.202400235).

The Front Cover highlights investigations of the reactivity of Cannabigerol (CBG) in organic solvents under both photochemical and acid catalyzed conditions, pointing out the key role of the photoexcited CBG* in the selective formation of a 2,2-disubstituted-chromane derivative (green path). On the other hand, in the presence of Brønsted-Lowry acids, two tertiary carbocations are competitively generated (I⁺, II⁺, orange and blue paths). Finally, when performing the reaction in toluene in the presence of BF₃*OEt₂, a Friedel Crafts-like alkylation of the solvent was noticed (purple paths). More information can be found in the Research Article by Daniele Merli, Stefano Protti, and co-workers (DOI: 10.1002/cptc.202400157).

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).

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.

Herein, novel borate-type photobase generators (PBGs) that generate a proazaphosphatrane known as Verkade's base (2,8,9-triisobuthyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane (TTP)) were developed for photopatterning using a high-pressure mercury lamp. Eight PBGs were synthesized, each featuring distinct borate substituents: phenyl, p-fluorophenyl, p-tolyl, p-methoxyphenyl, m-fluoro-p-methylphenyl, 4-biphenyl, 2-naphthyl, and 6-methoxy-2-naphthyl. The relation between these substituents and their light absorption characteristics was analyzed via ultraviolet–visible spectroscopy and time-dependent density functional theory calculations. The PBG with the 6-methoxy-2-naphthylborate group (TTP–tetrakis[2-(6-methoxynaphthyl)]borate (TTP–TMNB)) demonstrated substantial light absorption near 365 nm (the i-line of the high-pressure mercury lamp), generating approximately 60 % of the corresponding TTP in deuterated tetrahydrofuran (THF) upon exposure to 650 mJ/cm², as confirmed via ¹H nuclear magnetic resonance spectroscopy. To evaluate its photolithographic potential, TTP–TMNB was mixed with epoxy resin (jER1001) and a poly(methacrylic acid)-co-poly(methyl methacrylate) copolymer (PMA_1.6-co-PMMA₁₀₀) in THF. The resulting mixture was spin-coated onto a silicon wafer and irradiated with the i-line through a photomask to create a negative-tone image. The sensitivity and contrast of this photopolymer system were measured to be 45 mJ/cm² and 1.0, respectively; moreover, a clear 10-μm negative-tone resolution was achieved.

The ammonia oxidation reaction (AOR) exhibits significant potential for environmental remediation and energy utilization. Nevertheless, the complex reaction mechanism of the AOR poses numerous challenges to its application. To overcome these challenges and realize an efficient AOR process, a thorough understanding of every elementary reaction step, especially the cleavage of N−H bonds, is crucial. This review delves into the influence of N−H bond cleavage on the rate and selectivity of AOR, and summarizes the latest advancements in promoting this crucial step. Furthermore, we discuss the challenges faced by N−H bond cleavage and provide insights into the design of efficient catalytic AOR systems.

Fluorescence aggregated molecules tend to employ versatile opportunities in metal ion probe sensors and fluorescent lighting. To achieve this dual challenging task, currently synthesized three phenanthroimidazole-naphthalene-based compounds Pq-tBu-OH, Pq-mF-OH, and Pq-pF-OH are derived based on substitution at N₁ position for better photophysical and electrochemical properties. Compared experimental and theoretical calculations define the highest bandgap to be 2.75 eV of Pq-pF-OH, and the same molecule expressed a higher (348 °C) thermal decomposition. The calculated singlet and triplet energies found in the range of 3.24–3.67 and 2.70–2.72 eV indicate well energy transfer from S₁→S₀ (quantum yield of 23.36 %, lifetime is 4.05 ns). Among the numerous morphologies, the solid form exhibited improved intensive deep blue emission (x=0.159, y=0.051), and its InGaN LED results demonstrated a strong deep blue emission at 418 nm. Moreover, the fluorophores were experimentally visualizing the aggregation-caused quenching (ACQ) which enables the probing of Fe³⁺ ion. However, for the first time, the ACQ-assisted concept is applied through synthesized molecules for Fe³⁺ ion probing via fluorescence spectra, Job's plot calculation, and ¹H NMR results. In addition, the probe works excellently at a detection limit of 10 μM and it could also act as a potential competitor for lighting applications.

The hydroxylation of benzene to phenol in presence of hydrogen peroxide was performed using a new biphasic system consisting of a solid phase, a photocatalytically active monolithic polymer composite, immersed in an aqueous phase in which H₂O₂ is dissolved. In detail, ZnO photocatalytic particles were embedded into the hydrophobic syndiotactic polystyrene (sPS) polymer. Zinc oxide nanostructures (ZnO NSs) were synthesized by an electrochemical procedure. The surface morphology and structure of ZnO nanoparticles and ZnO-sPS monolithic aerogel composite (ZnO/sPS) were investigated by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy analysis. Photocatalytic results evidenced that, under UV irradiation, both ZnO NSs and biphasic system water-photocatalytic composites had a high benzene oxidative property but with very low phenol yield (<2 %) at pH=7. To enhance the phenol selective formation, the pH of the aqueous solution surrounding the photocatalytic polymer composite was modified. A phenol yield of about 94 % and benzene conversion higher than 99 % was obtained in alkaline conditions (pH=11).