Visible-light photocatalytic selective aerobic oxidation of thiols to disulfides on anatase TiO2

Linking Redox Characteristics to Dissolved Organic Matter Derived from Different Biowaste Composts: A Theoretical Modeling Approach Based on FT-ICR MS Analysis

Compost dissolved organic matter (DOM) is a complex mixture of redox-active organic molecules that impact various biogeochemical processes in soil environments. However, the impact of chemical complexity (heterogeneity and chemodiversity) on the electron accepting capacity (EAC) and electron donating capacity (EDC) of DOM molecules remains unclear, which hinders our ability to predict their environmental behavior and redox properties. In this study, the applicability of Vienna Soil Organic Matter Modeler 2 (VSOMM2) to the composting system based on the FT-ICR MS data has been validated. A molecular modeling approach using VSOMM2 and Schrödinger software was developed to quantitatively assess the redox sites and molecular interactions of compost DOM. Compost DOM molecules are categorized into three distinct groups based on their heterogeneous origins. In addition, we have developed 18 molecular models of compost DOM based on the links of molecules to EAC/EDC. Finally, Ar-OH, quinone, Ar-SH, and Ar-NH2 were identified as the redox sites; noncovalent contacts, H bonds, salt bridges, and aromatic-H bonds might be significant electronic transmission channels of compost DOM. Our findings contribute to the development of precise regulatory methods for functional molecules within compost DOM, providing the fine standards for composts matching specific ecosystem service requirements.

Mechanoluminescent Materials Enable Mechanochemically Controlled Atom Transfer Radical Polymerization and Polymer Mechanotransduction

Organic mechanophores have been widely adopted for polymer mechanotransduction. However, most examples of polymer mechanotransduction inevitably experience macromolecular chain rupture, and few of them mimic mussel's mechanochemical regeneration, a mechanically mediated process from functional units to functional materials in a controlled manner. In this paper, inorganic mechanoluminescent (ML) materials composed of CaZnOS-ZnS-SrZnOS: Mn2+ were used as a mechanotransducer since it features both piezoelectricity and mechanolunimescence. The utilization of ML materials in polymerization enables both mechanochemically controlled radical polymerization and the synthesis of ML polymer composites. This procedure features a mechanochemically controlled manner for the design and synthesis of diverse mechanoresponsive polymer composites.

Combining Brønsted base and photocatalysis into conjugated microporous polymers: Visible light-induced oxidation of thiols into disulfides with oxygen

Numerous applications in visible light photocatalysis have been found over conjugated microporous polymers (CMPs) whose function could be rationally designed at the molecular level. In this context, the oxidation of thiols into disulfides entails proton and electron transfer and thus requires both Brønsted base and photocatalysis, which could be both combined into CMPs. With carbazole as a Brønsted base and an electron donor, CMPs were constructed to implement the synergistic deprotonation and oxidation of thiols into disulfides in ethanol (C₂H₅OH). Gratifyingly, the bifunctional CMPs could activate molecular oxygen (O₂) to superoxide anion (O₂^•-) and promote the blue light-induced selective oxidation of thiols into symmetrical disulfides with high efficiency in C₂H₅OH. More remarkably, the highly selective formation of unsymmetrical disulfides could also be achieved without adding a Brønsted base. This work highlights the feasibility of combining cooperative photocatalysis into CMPs for versatile chemical transformations.

Synergy of Oxygen Vacancies and Acid Sites on N-Doped WO3 Nanobelts for Efficient C-C Coupling Synthesis of Benzoin Isopropyl Ether

The surface property of a photocatalyst, including surface acid sites and oxygen vacancies, plays a pivotal role in photocatalytic organic synthesis reactions. Benzoin isopropyl ether (BIE) is usually produced via polycondensation of benzaldehyde and catalyzed with highly toxic cyanide. Here, we report a green photocatalytic approach for the selective synthesis of BIE over WO₃ driven by a green-light-emitting diode. The improved photocatalytic activity can be attributed to the synergy of oxygen vacancies (V_Os) and acid sites over N-doped WO₃ nanobelts. The results revealed that reactant molecules were predominantly adsorbed and activated on surface oxygen vacancies (V_OSs) and the Brønsted acid promoted the etherification reaction; the introduction of V_Os and nitrogen altered the band structure and electronic properties, resulting in improved photocatalytic activity. Our work provides an efficient approach to the selective photocatalytic synthesis of organics over photocatalysts with finely tuned surface properties and band structures via defect and doping engineering.

Linkage Dependence of Interfacial Charge-Transfer Transitions in ZnO: Carboxylate versus Sulfur Linker

Interfacial charge-transfer transitions (ICTTs) between organic compounds and inorganic semiconductors have recently attracted much attention due to the unique features of a wide range of visible light absorption with colorless organic molecules and direct interfacial charge separation for their potential applications in photoenergy conversions and chemical sensing. As the research on ICTT has almost been limited to titanium oxide semiconductors such as TiO₂, the exploration of ICTT in other inorganic semiconductors is a high-priority issue. Recently, we demonstrated that ICTT is strongly induced by chemisorption of aromatic thiols on ZnO nanoparticles via the sulfur atom. Here, we report on ICTT in ZnO nanoparticles adsorbed with benzoic acid derivatives and the linkage dependence of ICTT in ZnO. We observed ICTT bands in the visible region upon adsorption of 4-(dimethylamino)benzoic acid (4-DMABA) and 3,4-dimethoxybenzoic acid (3,4-DMOBA) on ZnO nanoparticles via the carboxylate group. Notably, the ICTT absorption intensities are about 1 order of magnitude lower than those in the ZnO surface complexes with aromatic thiol compounds. Time-dependence density functional theory (TD-DFT) calculations well reproduce the linkage dependence of ICTT. This characteristic linkage dependence of ICTT in ZnO is attributed to the difference in the valence orbital of bridging atoms. The sulfur bridging atom with the larger 3p valence orbitals gives rise to strong electronic couplings between ZnO and adsorbates for ICTT, in contrast to very weak electronic couplings via the smaller 2p valence orbitals of the oxygen bridging atoms in the carboxylate linkage. Our research reveals the important linkage dependence of ICTT in ZnO and elucidates the mechanism.

Cooperative TiO2 photocatalysis with TEMPO and N-hydroxysuccinimide for blue light-driven selective aerobic oxidation of amines

TiO₂ has been the focus of attention in semiconductor photocatalysis for several decades because it can potentially settle the grand energy and environmental issues with earth-abundant elements of Ti and O. However, because of its wide band gap, TiO₂ can only collect UV light, hindering its practical applications under the illumination of sunlight. In view of this, an interesting phenomenon of light-driven adsorption of amines onto TiO₂ to form a visible light-absorbing complex was adapted to assemble smart photocatalysis. The endurance of this complex was eminently refurbished by blue light-driven continuous adsorption of amines. This in turn promoted a vital selective chemical transformation, blue light-driven selective oxidation of amines into imines with atmospheric dioxygen (O₂). More importantly, the inclusion of TEMPO and N-hydroxysuccinimide (NHS) into the smart photocatalytic system could cooperatively expedite the blue light-driven selective aerobic oxidation of amines into imines through dual independent reaction channels, resembling that of enzymatic catalysis. This work underscores the importance of manoeuvring multiple reaction channels by cooperative photocatalysis during selective chemical transformations.

An overview on recent development in visible light-mediated organic synthesis over heterogeneous photo-nanocatalysts

The implementation of heterogeneous photo-nanocatalysts in organic syntheses has been investigated greatly in the last decade as a result of the increasing demand to achieve the organic reactions via the use of green approaches and through the availability of visible light source. Herein, the presented results describe the basic concepts and state-of-the-art of fundamental insight into key features that influence the catalytic performance in organic reactions to investigate and optimize a broad range of catalyzed organic transformations, that benefit the researchers in academia and chemical industry fields.