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Water Science and Technology : a... Jun 2024Graphitic carbon nitride (g-CN) is a widely studied visible-light-active photocatalyst for low cost, non-toxicity, and facile synthesis. Nonetheless, its photocatalytic... (Review)
Review
Graphitic carbon nitride (g-CN) is a widely studied visible-light-active photocatalyst for low cost, non-toxicity, and facile synthesis. Nonetheless, its photocatalytic efficiency is below par, due to fast recombination of charge carriers, low surface area, and insufficient visible light absorption. Thus, the research on the modification of g-CN targeting at enhanced photocatalytic performance has attracted extensive interest. A considerable amount of review articles have been published on the modification of g-CN for applications. However, limited effort has been specially contributed to providing an overview and comparison on available modification strategies for improved photocatalytic activity of g-CN-based catalysts in antibiotics removal. There has been no attempt on the comparison of photocatalytic performances in antibiotics removal between modified g-CN and other known catalysts. To address these, our study reviewed strategies that have been reported to modify g-CN, including metal/non-metal doping, defect tuning, structural engineering, heterostructure formation, etc. as well as compared their performances for antibiotics removal. The heterostructure formation was the most widely studied and promising route to modify g-CN with superior activity. As compared to other known photocatalysts, the heterojunction g-CN showed competitive performances in degradation of selected antibiotics. Related mechanisms were discussed, and finally, we revealed current challenges in practical application.
Topics: Anti-Bacterial Agents; Light; Graphite; Catalysis; Nitrogen Compounds; Water Pollutants, Chemical; Photolysis; Photochemical Processes; Nitriles
PubMed: 38877630
DOI: 10.2166/wst.2024.166 -
Environmental Science & Technology Jul 2024This study addresses existing gaps in understanding the specific involvement of dissolved organic matter (DOM) fractions in antibiotic photolysis, particularly under...
Deciphering the Role of Microbial Extracellular and Intracellular Organic Matter in Antibiotic Photodissipation: Molecular and Fluorescent Profiling under Natural Radiation.
This study addresses existing gaps in understanding the specific involvement of dissolved organic matter (DOM) fractions in antibiotic photolysis, particularly under natural conditions and during DOM photobleaching. Employing fluorescent, chemical, and molecular analysis techniques, it explores the impact of extracellular and intracellular organic matter (EOM and IOM) on the photodissipation of multiclass antibiotics, coupled with DOM photobleaching under natural solar radiation. Key findings underscore the selective photobleaching of DOM fractions, propelled by distinct chemical profiles, influencing DOM-mediated antibiotic photolysis. Notably, lipid-like substances dominate in the IOM, while lignin-like substances prevail in the EOM, each uniquely responding to sunlight and exhibiting selective photobleaching. Sunlight primarily targets fulvic acid-like lignin components in EOM, contrasting the initial changes observed in tryptophan-like lipid substances in IOM. The lower photolability of EOM, attributed to its rich unsaturated compounds, contributes to an enhanced rate of indirect antibiotic photolysis (0.339-1.402 h) through reactive intermediates. Conversely, the abundance of aliphatic compounds in IOM, despite it being highly photolabile, exhibits a lower mediation of antibiotic photolysis (0.067-1.111 h). The triplet state excited DOM* plays a pivotal role in the phototransformation and toxicity decrease of antibiotics, highlighting microbial EOM's essential role as a natural aquatic photosensitizer for water self-purification. These findings enhance our understanding of DOM dynamics in aquatic systems, particularly in mitigating antibiotic risks, and introduce innovative strategies in environmental management and water treatment technologies.
Topics: Anti-Bacterial Agents; Photolysis
PubMed: 38874829
DOI: 10.1021/acs.est.4c01141 -
Science (New York, N.Y.) Jun 2024Nitrenes are a highly reactive, yet fundamental compound class. They possess a mono-valent nitrogen atom and usually a short life span, typically in the nanosecond...
Nitrenes are a highly reactive, yet fundamental compound class. They possess a mono-valent nitrogen atom and usually a short life span, typically in the nanosecond range. Here, we report on the synthesis of a stable nitrene by photolysis of the arylazide MFluindN (), which gave rise to the quantitative formation of the arylnitrene MFluindN () (MFluind = dispiro[fluorene-9,3'-(1',1',7',7'-tetramethyl-s-hydrindacen-4'-yl)-5',9''-fluorene]), that remains unchanged for at least 3 days when stored under argon atmosphere at room temperature. The extraordinary life span permitted the full characterization of by single crystal x-ray crystallography, EPR spectroscopy and SQUID magnetometry, which supported a triplet ground state. Theoretical simulations suggest in addition to the kinetic stabilization conferred by the bulky MFluind aryl substituent, that electron delocalization across the central aromatic ring contributes to the electron stabilization of .
PubMed: 38870274
DOI: 10.1126/science.adp4963 -
The Journal of Physical Chemistry. A Jun 2024Criegee intermediates exert a crucial influence on atmospheric chemistry, functioning as powerful oxidants that facilitate the degradation of pollutants, and...
Criegee intermediates exert a crucial influence on atmospheric chemistry, functioning as powerful oxidants that facilitate the degradation of pollutants, and understanding their reaction kinetics is essential for accurate atmospheric modeling. In this study, the kinetics of CHOO and -CHCHOO reactions with acetaldehyde (CHCHO) were investigated using a flash photolysis reaction tube coupled with the OH laser-induced fluorescence (LIF) method. The experimental results indicate that the reaction of -CHCHOO with CHCHO is independent of pressure in the range of 5-50 Torr when using Ar as the bath gas. However, the rate coefficient for the reaction between CHOO and CHCHO at 5.5 Torr was found to be lower compared to the near-constant values observed between 10 and 100 Torr. Furthermore, the reaction of -CHCHOO with CHCHO demonstrated positive temperature dependence from 283 to 330 K, with a rate coefficient of (2.11 ± 0.45) × 10 cm molecule s at 298 K. The activation energy and pre-exponential factor derived from the Arrhenius plot for this reaction were determined to be 2.32 ± 0.49 kcal mol and (1.66 ± 0.61) × 10 cm molecule s, respectively. In comparison, the reaction of CHOO with CHCHO exhibited negative temperature dependence, with a rate coefficient of (2.16 ± 0.39) × 10 cm molecule s at 100 Torr and 298 K and an activation energy and a pre-exponential factor of -1.73 ± 0.31 kcal mol and (1.15 ± 0.21) × 10 cm molecule s, respectively, over the temperature range of 280-333 K.
PubMed: 38868987
DOI: 10.1021/acs.jpca.4c01374 -
Environmental Geochemistry and Health Jun 2024In the pursuit of efficient photocatalytic materials for environmental applications, a new series of g-CN/N-doped CeO nanocomposites (g-CN/N-CeO NCs) was synthesized...
In the pursuit of efficient photocatalytic materials for environmental applications, a new series of g-CN/N-doped CeO nanocomposites (g-CN/N-CeO NCs) was synthesized using a straightforward dispersion method. These nanocomposites were systematically characterized to understand their structural, optical, and chemical properties. The photocatalytic performance of g-CN/N-CeO NCs was evaluated by investigating their ability to degrade methylene blue (MB) dye, a model organic pollutant. The results demonstrate that the integration of g-CN with N-doped CeO NCs reduces the optical energy gap compared to pristine N-doped CeO, leading to enhanced photocatalytic efficiency. It is benefited from the existence of g-CN/N-CeO NCs not only in promoting the charge separation and inhibits the fast charge recombination but also in improving photocatalytic oxidation performance. Hence, this study highlights the potential of g-CN/N-CeO NCs as promising candidates for various photocatalytic applications, contributing to the advancement of sustainable environmental remediation technologies.
Topics: Methylene Blue; Cerium; Nanocomposites; Catalysis; Light; Water Pollutants, Chemical; Graphite; Photochemical Processes; Photolysis; Nitrogen Compounds
PubMed: 38864996
DOI: 10.1007/s10653-024-02007-1 -
Journal of the American Chemical Society Jun 2024Boraphenalenes, compounds in which one carbon atom in the phenalenyl skeleton is replaced with a boron atom, have attracted attention for their solid-state and...
Boraphenalenes, compounds in which one carbon atom in the phenalenyl skeleton is replaced with a boron atom, have attracted attention for their solid-state and electronic structures; however, the construction of boraphenalene skeletons remains challenging because of the lack of suitable methods. Through this study, we showed that the tandem borylative cyclization of -symmetric dehydrobenzo[12]annulenes produces a new class of fully fused boron-atom-embedded polycyclic hydrocarbons possessing a 9b-boraphenalene skeleton. The obtained compounds exhibited high electron-accepting characteristics, and their two-step redox process was reversible in the reductive region, involving interconversion of 9b-boraphenalene between Hückel aromaticity and antiaromaticity. Notably, the benzo[]fluorene-fused derivative exhibited a stepwise single-crystal-to-single-crystal (SCSC) phase transition triggered by thermal annealing. Intermolecular electron coupling calculation of the crystal structures suggested a significant improvement of charge transporting ability associated with the SCSC phase transition. Moreover, adequate photoconductivity was observed for the single crystals before and after the SCSC phase transition through flash photolysis-time-resolved microwave conductivity.
PubMed: 38861619
DOI: 10.1021/jacs.4c02407 -
Chemistry (Weinheim An Der Bergstrasse,... Jun 2024A chromium complex carrying two benzanellated N-heterocyclic phosphenium (bzNHP) ligands was prepared by a salt metathesis approach. Spectroscopic studies suggest that...
A chromium complex carrying two benzanellated N-heterocyclic phosphenium (bzNHP) ligands was prepared by a salt metathesis approach. Spectroscopic studies suggest that the anellation enhances the π-acceptor ability of the NHP-units, which is confirmed by the facile electrochemical reduction of the complex to a spectroscopically characterized radical anion. Co-photolysis with H2 allowed extensive conversion into a σ-H2-complex, which shows a diverse reactivity towards donors and isomerizes under H-H bond fission and shift of a hydride to a P-ligand. The product carrying phosphenium, phosphine and hydride ligands was also synthesized independently and reacts reversibly with CO and MeCN to yield bis-phosphine complexes under concomitant Cr-to-P-shift of a hydride. In contrast, CO2 was not only bound but reduced to give an isolable formato complex, which reacted with ammonia borane under partial recovery of the metal hydride and production of formate. Further elaboration of the reactions of the chromium complexes with CO2 and NH3BH3 allowed to demonstrate the feasibility of a Cr-catalyzed transfer hydrogenation of CO2 to methanol. The various complexes described were characterized spectroscopically and in several cases by XRD studies. Further insights in reactivity patterns were provided through (spectro)electrochemical studies and DFT calculations.
PubMed: 38860887
DOI: 10.1002/chem.202401714 -
Molecular Pharmaceutics Jul 2024Dacarbazine (DTIC) is a widely prescribed oncolytic agent to treat advanced malignant melanomas. Nevertheless, the drug is known for exhibiting low and pH-dependent...
Dacarbazine (DTIC) is a widely prescribed oncolytic agent to treat advanced malignant melanomas. Nevertheless, the drug is known for exhibiting low and pH-dependent solubility, in addition to being photosensitive. These features imply the formation of the inactive photodegradation product 2-azahypoxanthine (2-AZA) during pharmaceutical manufacturing and even drug administration. We have focused on developing novel DTIC salt/cocrystal forms with enhanced solubility and dissolution behaviors to overcome or minimize this undesirable biopharmaceutical profile. By cocrystallization techniques, two salts, two cocrystals, and one salt-cocrystal have been successfully prepared through reactions with aliphatic carboxylic acids. A detailed structural study of these new multicomponent crystals was conducted using X-ray diffraction (SCXRD, PXRD), spectroscopic (FT-IR and H NMR), and thermal (TG and DSC) analyses. Most DTIC crystal forms reported display substantial enhancements in solubility (up to 19-fold), with faster intrinsic dissolution rates (from 1.3 to 22-fold), contributing positively to reducing the photodegradation of DTIC in solution. These findings reinforce the potential of these new solid forms to enhance the limited DTIC biopharmaceutical profile.
Topics: Solubility; Crystallization; X-Ray Diffraction; Dacarbazine; Photolysis; Spectroscopy, Fourier Transform Infrared; Magnetic Resonance Spectroscopy; Calorimetry, Differential Scanning
PubMed: 38858241
DOI: 10.1021/acs.molpharmaceut.4c00393 -
The Journal of Physical Chemistry. A Jun 2024Five biogenic unsaturated alcohols have been investigated under simulated atmospheric conditions regarding their gas-phase OH reactivity. The gas-phase rate coefficients...
Five biogenic unsaturated alcohols have been investigated under simulated atmospheric conditions regarding their gas-phase OH reactivity. The gas-phase rate coefficients of OH radicals with 2-methyl-3-buten-2-ol (), 3-methyl-2-buten-1-ol (), 3-methyl-3-buten-1-ol (), 2-methyl-3-buten-1-ol (), and 3-methyl-3-buten-2-ol () at 298 ± 2 K and 1000 ± 10 mbar total pressure of synthetic air were determined under low- and high-NO conditions using the relative kinetic technique. The present work provides for the first time the rate coefficients of gas-phase reactions of hydroxyl radicals with 2-methyl-3-buten-1-ol and 3-methyl-3-buten-2-ol. The following rate constants were measured (in 10 cm molecule s): = 6.32 ± 0.49, = 14.55 ± 0.93, = 10.04 ± 0.78, = 5.31 ± 0.37, and = 11.71 ± 1.29. No significant differences in the measured rate coefficients were obtained when either 365 nm photolysis of CHONO in the presence of NO or 254 nm photolysis of HO was used as a source of OH radicals. Reactivity toward other classes of related compounds such as alkenes and saturated alcohols is discussed. A comparison of the structure-activity relationship (SAR) estimates derived from the available accepted methodologies with experimental data available for unsaturated alcohols is provided. Atmospheric lifetimes for the investigated series of alkenols with respect to the main atmospheric oxidants are given and discussed.
PubMed: 38857889
DOI: 10.1021/acs.jpca.4c02287 -
Inorganic Chemistry Jun 2024The catalytic efficacy of the monobipyridyl (η--Cymene)Ru(II) half-metallocene, [(-Cym)Ru(bpy)Cl] was evaluated in both mixed homogeneous (dye + catalyst) and...
Photocatalytic Conversion of CO to Formate/CO by an (η--Cymene)Ru(II) Half-Metallocene Catalyst: Influence of Additives and TiO Immobilization on the Catalytic Mechanism and Product Selectivity.
The catalytic efficacy of the monobipyridyl (η--Cymene)Ru(II) half-metallocene, [(-Cym)Ru(bpy)Cl] was evaluated in both mixed homogeneous (dye + catalyst) and heterogeneous hybrid systems (dye/TiO/Catalyst) for photochemical CO reduction. A series of homogeneous photolysis experiments revealed that the (-Cym)Ru(II) catalyst engages in two competitive routes for CO reduction (CO to formate conversion via Ru-hydride vs CO to CO conversion through a Ru-COOH intermediate). The conversion activity and product selectivity were notably impacted by the p value and the concentration of the proton source added. When a more acidic TEOA additive was introduced, the half-metallocene Ru(II) catalyst leaned toward producing formate through the Ru-H mechanism, with a formate selectivity of 86%. On the other hand, in homogeneous catalysis with TFE additive, the CO-to-formate conversion through Ru-H was less effective, yielding a more efficient CO-to-CO conversion with a selectivity of >80% (TON of 140 and TON of 626 over 48 h). The preference between the two pathways was elucidated through an electrochemical mechanistic study, monitoring the fate of the metal-hydride intermediate. Compared to the homogeneous system, the TiO-heterogenized (-Cym)Ru(II) catalyst demonstrated enhanced and enduring performance, attaining TONs of 1000 for CO-to-CO and 665 for CO-to-formate.
PubMed: 38856726
DOI: 10.1021/acs.inorgchem.3c03879