Journal of Photochemistry and Photobiology C: Photochemistry Reviews最新文献

During the past two decades, there is an explosive growth of numerous scientific researches on dual-emitting fluorescence ratiometric nanoprobes (FRNPs). FRNPs adopt dual-signal ratiometry as signal output toward specific targets, and exhibit unique in-built signal self-calibration function and high accuracy for target detection. Especially, FRNPs can perform high-performance detection of in-vitro/in-vivo pH. These explored FRNPs-pH systems were extensively applied to pH-sensing, imaging and therapeutic applications at the levels of living cells and small animals. Thereby, this review has systematically summarized the promising FRNPs-pH systems reported in recent years. The first section has clearly introduced dual-emission fluorescence (FL) ratiometric modes and FL sensing mechanisms during the construction and application processes. The second section wholly summarizes various construction methods of FRNPs-pH systems based on different compositions and structures. The third section rationally discusses potential applications of FRNPs-pH systems, referring to FL bioimaging at the levels of living cells and small animals, pH-sensing and imaging detection at the levels of whole cells, organelles, tissues and organs, as well as FL imaging-guided tumor therapy. Furthermore, the current status, potential challenges and development perspectives in following researches are analyzed reasonably. This comprehensive and timely review promotes further explorations of multifunctional luminescent nanoprobes and versatile sensing materials for highly efficient biomedical applications.

Photocatalysis holds the tantalizing potential to satisfy global energy demand, reduce greenhouse effect, and resolve environmental contamination. In particular, chemical transformation of biomass by sunlight has delivered a sustainable and decarbonized approach to the production of chemicals and fuels by using the abundant resources on earth. As the major byproduct in biodiesel processing, glycerol has introduced itself as a renewable, bio-derived feedstock for the production of value-added chemicals. To this end, the development of sunlight-driven “glycerochemistry” capable of transforming glycerol into high value-added chemicals has received much research attention over recent years. This Review summarizes the recent progress achieved in the realization of value-added chemical production from photocatalytic (PC) and photoelectrochmeical (PEC) glycerol oxidation. Spotlights are shined on the design of critical photoactive materials and the devising of reliable strategies that enable a rational control over the selectivity toward a desired product. Additionally, it addresses the current gaps in the interpretation of a veritable reaction mechanism both experimentally and theoretically. Lastly, current challenges and future prospects are pinpointed in order to accelerate the widespread deployment of PC and PEC glycerol valorization in academia and industries.

Mesoporous materials possess unique structural characteristics, such as high surface area, large pore volume, and interconnected pore networks, which make them ideal candidates for photocatalysis. The objective of this review is to critically analyse the synthesis methods, characterization techniques, and photocatalytic performance of mesoporous titania films for photocatalysis. The article begins by providing a short overview of the chemical-physical processes involved in photocatalysis of titania. It highlights the need for efficient photocatalytic materials with enhanced surface area and light harvesting capabilities. Subsequently, the synthesis methods for creating mesoporous titania films are discussed, including sol-gel chemistry, templating approaches, and self-assembly techniques. Emphasis is placed on the control of pore size, distribution, and film thickness to optimize the photocatalytic performance. The influence of synthesis parameters on the film porosity, crystallinity, and surface area is examined in detail. Furthermore, the review highlights recent advancements in the field, including strategies to enhance the photocatalytic performance of mesoporous titania films through doping, surface modification, and heterostructure formation. These approaches aim to improve the light absorption, charge separation, and reactant accessibility, thus maximizing the utilization of solar energy for efficient photocatalysis. In conclusion, mesoporous titania films demonstrate great potential as effective photocatalytic materials. Their unique structural features, combined with proper synthesis and characterization, contribute to enhanced photocatalytic performance. Further research and development in this area may lead to the design and fabrication of advanced mesoporous titania films for a wide range of environmental and energy applications.

Although numerous photocatalysts, such as organic compounds and metallic complexes, have been systematically designed and synthesized for visible light-induced photopolymerization, their disadvantages, such as toxicity and poor water dispersibility, cannot be neglected in practical production. Hence, high-performance photoinitiators based on nanomaterials, such as carbon dots and carbon nitrides, have recently been reported due to their favorable characteristics of eco-friendliness, high biocompatibility, etc. In this review, carbon-family-based photocatalysts reported in the last five years are thoroughly discussed by the classifications in terms of their photoinitiation mechanisms, such as photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization (PET-RAFT), atom transfer radical polymerization (ATRP), cationic polymerization (CP) and free radical polymerization (FRP). Carbon family materials play significant roles in the applications of visible light-induced photopolymerization, such as 3D printing and hydrogel materials fabrication. Specifically, they can not only initiate photopolymerization but also endow products with specific chemical or physical properties, e.g., nontoxic, economical, and facile synthesis routes. Finally, reports on newly developed carbon-family nanomaterials, such as silicon quantum dots, are introduced and discussed as perspectives for photopolymerization, which could inspire researchers in the relevant fields.

Mechanochemistry, a burgeoning field in green chemistry, has been utilized frequently to synthesize various organic molecules, metal complexes, coordination polymers (CPs) and metal-organic frameworks (MOFs) in the solid state from the reactants with very little or no solvent. These mechanical grinding reactions also resulted in successful isolation of materials that are inaccessible otherwise from solution. On the contrary, single crystal X-ray crystallographic technique is routinely used to study the solid-state structural transformations driven by thermal and photochemical methods. In the absence of single crystals, [2 + 2] photocycloaddition reactions can easily be monitored by NMR spectroscopy along with other suitable physical and analytical techniques. During mechanical grinding, several structural changes have been found to take place with the loss of single crystalline nature. Here from our personal perspective, we reviewed how this [2 + 2] cycloaddition reactions have been used effectively to monitor the structural changes induced by mechanochemical grinding. These structural transformations are caused by the pedal motion of olefin bonds, conformational changes of molecular fragments, movements of molecules, change in the composition by absorbing water from the atmosphere, anisotropic expansion of volume, rotation of helical coordination polymers, dimensionality change, loss of coordinating and lattice solvents and catalytic role of template molecules on the [2 + 2] photocycloaddition reactivity.

This review focuses on the many research that have been undertaken in visible-light driven environmental photocatalysis field employing Metal-Organic Framework (MOF) materials for the removal of aqueous pollutants. Correlations between their structural and functional features, and the reactional pathways for pollutant degradation were also addressed, with a particular emphasis on the syntheses and on the charge transfer complexes occurring in the MOF compounds. The extensive possibilities for modifying the properties of MOFs in diverse applications were critical while dealing with a variety of contaminants with different properties. Indeed, because of the infinite number of combinations of different inorganic poly-oxo clusters and organic linkers, and to the possibility of tailoring other variables such as functional groups, pore size, defects, and incorporation of other materials (dyes, semiconductors, metal nanoparticles, covalent organic frameworks, carbon-based materials, magnetic compounds, and inert carriers), MOFs have a high potential to lead the photocatalytic field. Furthermore, the use of mixed methods has shown to be a legitimate and fascinating technique for further developing these systems while considering their strengths and weaknesses. Despite considerable advancements in MOF-based photocatalysts, significant obstacles remain. However, the research of heterogeneous photocatalysis dates back to the 1970 s, but the discussion of MOF materials is even more recent, with just a few decades spent investigating these systems. Nonetheless, tremendous breakthroughs in this area have been made, from structural design to computer simulations, and reports of various MOF materials have constantly increased in the previous several years. As a result, combining the collaborative efforts of researchers from many domains, the future appears to hold promising prospects for MOF-based photocatalysts.

Research over dye-sensitized hydrogen generation using TiO₂ semiconductor photocatalysts has gained abiding importance over the past three decades due to its manifold advantages over other photocatalytic systems for the production of clean energy fuels. The single-step excitation of the electrons over the sensitizer molecules anchored at the TiO₂ semiconductor serves as a driving source to facilitate the electron effect transfers, thus prompting the visible-light driven photocatalytic hydrogen generation activities. Though many review articles that evaluate the performance of such dye-sensitized semiconductor particulate systems are available in the literature, research progress made in the last few years since 2016 is not yet systematically reviewed. In this article, we therefore, systematically review the development of new dye-sensitizers that include metal-free organic dyes, metal-based sensitizers, and donor-bridged-acceptor (D-π-A) type dye-sensitizers, and their performances in sensitization of the TiO₂ semiconductor photocatalyst towards visible light driven hydrogen generation through water splitting. It has been chronicled that the aforesaid sensitizers are capable of harvesting a broader part of the solar spectrum, and could achieve photocatalytic H₂ production with varying degrees of success. The results discussed in this review afford a significant scope of rationalizating the factors that govern the H₂ production activity over the dye-modified TiO₂ photocatalyst, and provide a basis for further research towards the realization of high-performing dye-sensitized H₂ production photocatalytic system. The prospect of artificial intelligence (AI)-machine learning (ML) based modeling for quicker design and development of dye-sensitized TiO₂ based photocatalytic solar to fuel conversion system has been briefly discussed in the article.

Triplet-triplet annihilation photon up-conversion (TTA-PUC) has gained immense attention among the scientific community in the last decade due to its application in the fields of energy, biology, and photocatalytic organic synthesis. One of the main aims to improve the efficiency of these low-to-high photon-energy conversion is to reduce energy losses during the intersystem crossing (ISC). Since 2015, many strategies have been reported to address this challenge and a significant update has been noticed in this field. This review is aimed to critically analyze these updates and provide an outlook for the future. A detailed mechanism of ISC in thermally activated delayed-fluorescence (TADF) molecules that possess a small singlet−triplet energy gap, is discussed with a focus on its deeper understanding and the impact of molecular design. In this context, a range of selected organic and inorganic TADF molecules are thoroughly evaluated. Osmium(II) complexes that exhibit a spin-forbidden metal-to-ligand charge-transfer (³MLCT) transition in their Vis-NIR-IR absorption spectra and can be excited directly into their triplet state, thereby bypassing the energy loss during ISC, are also debated in sufficient detail for their advantages as well as shortcomings in being used in TTA-PUC. This work aims at reviewing the latest progress in this field, understanding the fundamental ISC mechanism of these photosensitizers, and critically addressing the challenges that are faced in this field. This review is anticipated to serve as a helpful script for identifying future directions and designing molecular sensitizers for TTA-PUC, which can sensitize the triplet state with minimum energy loss during ISC and can be helpful for increasing the anti-Stokes shift in TTA-PUC.

Mitochondria is the cell's energy powerhouse and regulate most of the metabolism process through the inherent mitochondrial genes (mtDNA). The control of mtDNA replication and transcription is known to be mediated by noncanonical forms of guanine-rich nucleotides G-quadruplexes (G4s). These putative and transient guanine-based structures and their dynamics are closely associated with mtDNA deletion breakpoints pertaining to fatal diseases such as cancers, hypertension, diabetes, etc. The precise reason for the origin of G4s at deletion breakpoints in the heavy strand and during the replication process has not yet been identified, owing to its complex biochemical phenomenon. Biomolecular structure, typically having a size of 5–10 nm with an average life span of seconds, strongly demands high-end instruments to explore the precise biochemical mechanism and dynamics (folding or unfolding) in biological systems. In that sense, since the last decade, tremendous efforts have been kept in X-ray crystallography, circular dichroism spectroscopy (CD), nuclear magnetic resonance spectroscopy (NMR), immunofluorescence, and the mtG4-ChIP methods to recognize and characterize the G4s structures in physiological conditions. Owing to their non-invasiveness, robustness, and high spatio-temporal resolution at the molecular level, fluorescence methods have been exploited to recognize noncanonical forms of nucleic acids even at the subcellular level. In light of this, from 2015 until today, the documentation of photophysical and bioanalytical capabilities of mtG4s recognizing small and quencher-free fluorescent probes has not yet been reported. Considering the plethora of G4s propensity with mtDNA replication, transcription, oxidative phosphorylation, glycolysis etc. In the current article, we have systematically documented small fluorescent probes that have been exclusively used to recognize mtG4 in cellular conditions with photophysical and biophysical properties. Furthermore, the probe's designing rationale binding mechanism, readout system, cellular localization, and cytotoxicity were tabulated.