Covalent organic framework isomers with divergent photocatalytic properties.

A pair of isomeric Py-BT-COFs with the same composition, but slightly different atomic arrangements, were designed and synthesized. The minute structural variations of the Py-BT-COF isomers generated significantly different redox and photophysical properties and correspondingly led to different photocatalytic manifestations in H2 evolution and rhodamine B degradation.

Radiation-Activated Resiquimod Prodrug Nanomaterials for Enhancing Immune Checkpoint Inhibitor Therapy.

Immune checkpoint inhibitor (ICI) therapy is effectively employed in treating various malignancies. However, the response rate is constrained to 5-30%, which is attributed to differences in immune responses across different tumors. Overcoming all obstacles of multistep immune activation with monotherapy is difficult. Here, maleimide-modified resiquimod (R848) prodrug nanoparticles (MAL-NPs) are reported and combined with radiotherapy (RT) and anti-PD1 to enhance ICI therapy. MAL-NPs can promote antigen endocytosis by dendritic cells and are radio-reduced to produce R848. When combined with RT, MAL-NPs can augment the concentration of nanoparticles at tumor sites and be selectively radio-reduced within the tumor, thereby triggering a potent antitumor immune response. The systemic immune response and long-term memory efficacy induced by MAL-NPs + RT + anti-PD1 significantly inhibit the abscopal tumor growth and prevent tumor recurrence. This strategy can achieve systemic therapy through selective training of the tumor immune microenvironment, offering a new approach to overcome the obstacles of ICI therapy.

Recent Progress in Porphyrin/g-C3N4 Composite Photocatalysts for Solar Energy Utilization and Conversion.

Transforming solar energy into chemical bonds is a promising and viable way to store solar energy. Porphyrins are natural light-capturing antennas, and graphitic carbon nitride (g-C3N4) is an effective, artificially synthesized organic semiconductor. Their excellent complementarity has led to a growing number of research papers on porphyrin/g-C3N4 hybrids for solar energy utilization. This review highlights the recent progress in porphyrin/g-C3N4 composites, including: (1) porphyrin molecules/g-C3N4 composite photocatalysts connected via noncovalent or covalent interactions, and (2) porphyrin-based nanomaterials/g-C3N4 composite photocatalysts, such as porphyrin-based MOF/g-C3N4, porphyrin-based COF/g-C3N4, and porphyrin-based assembly/g-C3N4 heterojunction nanostructures. Additionally, the review discusses the versatile applications of these composites, including artificial photosynthesis for hydrogen evolution, CO2 reduction, and pollutant degradation. Lastly, critical summaries and perspectives on the challenges and future directions in this field are also provided.

Fascinating isomeric covalent organic frameworks.

Isomeric covalent organic frameworks possessing the same chemical constitutions but different atomic arrangement structures and physicochemical properties are fascinating branches of covalent organic frameworks (COFs). However, the rational design and targeted synthesis of isomeric COFs remain conundrums, so the investigation of isomeric COFs is still in a fledging period. According to the diversity of frameworks, positional isomers with similar structures and framework isomers having distinct constructions are the main existing subspecies of isomeric COFs. In this review, we focus on the research progress and substantial achievements in this fascinating embranchment and systematically summarize and highlight the design principles of both positional isomeric and framework isomeric COFs, which will potentially facilitate further exploitation and investigation of novel isomeric COFs. The application and structure-property relationship of these isomeric COFs have been briefly introduced. Moreover, key constraints of current isomeric COFs and further advancement of this promising field are proposed and anticipated.

Synthesis of the ZnTPyP/WO3 nanorod-on-nanorod heterojunction direct Z-scheme with spatial charge separation ability for enhanced photocatalytic hydrogen generation.

The direct Z-scheme photocatalytic system can effectively improve the separation efficiency of photogenerated carriers through the photosynthesis-based photocarrier transport model. In this study, zinc porphyrin-assembled nanorods (ZnTPyP) and WO3 nanorods' nanorod-on-nanorod heterojunctions (ZnTPyP/WO3) were successfully prepared through a simple modified acid-base neutralization micelle-confined assembly method using WO3 nanorods as the nucleation template and ZnTPyP as building blocks. ZnTPyP achieved a controllable assembly onto WO3 nanorods through N-W coordination. ZnTPyP/WO3 nanorod-on-nanorod heterojunctions exhibited a structure-dependent photocatalytic performance for hydrogen production. The ZnTPyP/WO3 nanorod-on-nanorod heterojunctions exhibited a optimal hydrogen production rate (74.53 mmol g-1 h-1) using Pt as the co-catalyst, which was 2.64 times that of the ZnTPyP self-assembled nanorods. The improvement in the photocatalytic hydrogen production efficiency could be mainly attributed to the direct Z-scheme electron-transfer mechanism from WO3 to ZnTPyP. This is the first report of an approach using porphyrin-assembled nanostructures to construct organic-inorganic Z-scheme photocatalysts. This study offers valuable information for preparing new efficient photocatalysts based on organic supramolecular orderly aggregate materials.

Zn (II) Porphyrin Built-in D-A Covalent Organic Framework for Efficient Photocatalytic H2 Evolution.

Covalent organic frameworks (COFs) with donor-acceptor (D-A) units are credible photocatalysts for their per-designed structure, inherent porosity, large surface area, splendid stability and so forth. Developing COFs with an excellent photocatalytic efficiency for hydrogen evolution is of a great significance in alleviating the energy crisis. Herein, a D-A type imine-linked crystalline Zn-Por-TT COF was fabricated successfully via the co-polymerization of electron-deficient Zinc (II) 5,10,15,20-tetrakis(para-aminophenyl) porphyrin (Zn-TAPP), and electron-rich thieno[3,2-b]thiophene-2,5-dicarbaldehyde (TT). Profiting from the D-A complex structure, the obtained Zn-Por-TT COF showcases an excellent photocatalytic activity with a hydrogen evolution rate of 8200 µmol/g/h, while the Zn-TAPP monomer presents practically no capacity for the generation of hydrogen under identical conditions. In addition, the counterparts Por-TT COF and COF-366-Zn were employed to illustrate the enhancement of the photocatalytic performance by metal catalytic sites and D-A structures. In addition, the counterparts Por-TT COF and COF-366-Zn were employed to illustrate the enhancement of metal catalytic sites and D-A structures for the photocatalytic performance.

Poly(divinylbenzene) as a fiber coating for headspace solid-phase microextraction of polycyclic aromatic hydrocarbons from river water.

Porous polydivinylbenzene microspheres with high specific surface area were prepared by distillation-precipitation polymerization, and were used as the coating material in headspace solid phase microextraction for extracting polycyclic aromatic hydrocarbons. Compared with the other reported sorbents, PDVB exhibits lower cost and higher extraction efficiency, and the enrichment factors can reach 5963-16 720.

Self-Assembled Porphyrin Nanoleaves with Unique Crossed Transportation of Photogenerated Carriers to Enhance Photocatalytic Hydrogen Production.

The preparation of self-assembled porphyrins with orderly stacked nanostructures for emulating natural photosynthesis has stimulated extensive efforts to optimize the energy conversion efficiency. However, the elucidation of how orderly stacked structures promote photocatalysis at the molecular level remains a great challenge. Here, unique porphyrin nanoleaves with designed and ordered structure are synthesized and show a hydrogen evolution rate higher than that of commercial powder. Photodeposition of cocatalysts and Kelvin probe force microscopy measurement suggest selective aggregation of photogenerated electrons and holes at different active sites. Combined with theoretical calculations, we find that the orderly packing changes molecular symmetry and induces a molecular dipole, which increases linearly along the π-π stacking direction and forms a strong built-in electric field. The built-in electric field drives photogenerated electrons and holes for the unique crossed transportation along different directions. These findings reveal how orderly stacked structures promote photocatalysis and provide a novel approach for highly efficient water splitting.

Microemulsion-Assisted Self-Assembly and Synthesis of Size-Controlled Porphyrin Nanocrystals with Enhanced Photocatalytic Hydrogen Evolution.

Design and engineering of highly efficient light-harvesting nanomaterial systems to emulate natural photosynthesis for maximizing energy conversion have stimulated extensive efforts. Here we present a new class of photoactive semiconductor nanocrystals that exhibit high-efficiency energy transfer for enhanced photocatalytic hydrogen production under visible light. These nanocrystals are formed through noncovalent self-assembly of In(III) meso-tetraphenylporphine chloride (InTPP) during microemulsion assisted nucleation and growth process. Through kinetic control, a series of uniform nanorods with controlled aspect ratio and high crystallinity have been fabricated. Self-assembly of InTPP porphyrins results in extensive optical coupling and broader coverage of the visible spectrum for efficient light harvesting. As a result, these nanocrystals display excellent photocatalytic hydrogen production and photostability under the visible light in comparison with the commercial InTPP porphyrin powders.