Search

Photosensitization of semiconductors by excitation of chiral plasmonic metallic nanostructures has attracted much attention, not only for the analysis and detection of circularly polarized light but also for its potential applications in chiral photosynthesis. Although there have been reports on the detection of semiconductor-sensitized current in chiral nanostructures precisely fabricated by physical vapor deposition and/or lithography techniques, there have been no studies using plasmonic metal nanocolloids synthesized by chemical processes. In this study, we report the establishment of a fabrication method for large-area chiral photoelectrodes and the semiconductor photosensitization phenomenon realized using chiral plasmonic nanoparticles. Chiral plasmonic Au nanoparticles prepared by previously reported colloidal methods were immobilized onto a TiO2 thin film electrode by electrophoresis. When TiO2 electrodes loaded with chiral Au nanoparticles synthesized using L-cysteine were irradiated with circularly polarized light, left circularly polarized light irradiation at a wavelength of 500–600 nm generated a larger anodic photocurrent than right circularly polarized light irradiation at the same wavelength. This trend was reversed for TiO2 electrodes immobilized with colloidal Au nanoparticles synthesized with D-cysteine. From these results, we conclude that the efficiency of photocurrent generation by chiral plasmon excitation can be controlled by the polarization direction of the incident light. [ABSTRACT FROM AUTHOR]

In this work, we evaluate the bonding characteristics and interfacial electron transfer dynamics of three heteroleptic ruthenium photosensitizers featuring different terpyridine (tpy) acceptor end configurations through quantum-chemical calculations. These photosensitizers feature tpy ligands with a mono/tricarboxylic acid or a phenyl-carboxylic acid anchor and a trans-disposed –NCS and N-heterocyclic carbene ligand in a C^N donor set. Adiabatic transitions reveal significant overlap between higher-excited and ground-state orbitals and correlate with the experimentally observed anti-Kasha fluorescence. In all complexes, two carboxylate-O atoms of the central anchor effectively bind with TiO2 by bridging two titanium sites. However, appending an additional anchor on each peripheral pyridine of tpy renders binding through only one anchor's –C＝O atom to TiO2. Contrary to the complex bearing three anchors, those featuring monocarboxylate-functionalized tpy exhibit faster electron injection within 100 fs. In all, this study provides insights into the photosensitization attributes of the ruthenium complexes for dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

A visible‐light triplet photocatalyst 5‐acetyl‐2‐mercapto‐benzoic acid methyl ester (AcBSH) was developed through introducing acetyl into benzenethiolate to improve the efficiency of intersystem crossing (ISC) and using o‐methoxyformyl to increase the molar extinction coefficient. In the photocatalytic system of AcBSH, the reductive dearomatization of N‐arylformylindoles is achieved to afford the desired indolines in moderate to excellent yields, including both indoles without (1) and with 2‐substituent (2). The 2‐substituent is a steric hindrance for the conjugation between benzoyl and indole moiety, and makes indole 2 and indole 1 exhibit different reduction potentials (Ered) and different triplet energy levels (ΔET). Thereby, two kinds of substrates undergo primarily two photocatalytic pathways: i) successive SET/protonation pathway, which merging photosensitization via triplet‐triplet energy transfer (EnT) and photoinduced SET for substrates 1, and ii) single electron transfer (SET) from the triplet photocatalyst and a concerted hydrogen atom transfer (HAT) process for substrates 2. [ABSTRACT FROM AUTHOR]

A photocatalytic electrochemical aptasensor for the detection of chloramphenicol（CAP）antibiotic residues in water by utilizing SYBR Green I（SG）and chemically exfoliated MoS 2 （ce-MoS 2 ） as synergistically signal-amplification platforms. [Display omitted] • A novel photocatalytic electrochemical aptasensor was developed for the detection of chloramphenicol (CAP) antibiotic residues in water. • Photosensitized SYBR Green I (SG) and chemically stripped MoS 2 (ce-MoS 2) were intercalated into the groove of the resulting dsDNA and use as a synergistic signal-amplification platform. • Upon light irradiation, the photocatalytic reaction was activated, generating singlet oxygen that efficiently cleaved the dsDNA, leading to a significant increase in the current of [Fe(CN) 6 ]3-/4-. • The aptasensor demonstrated good selectivity towards CAP in the presence of interfering antibiotics. • The aptasensor exhibited a linear relationship between CAP and logarithmic concentrations from 20 to 1000 nM, with a detection limit (3σ) of 3.391 nM. This study reports the development of a photocatalytic electrochemical aptasensor for the purpose of detecting chloramphenicol (CAP) antibiotic residues in water by utilizing SYBR Green I (SG) and chemically exfoliated MoS 2 (ce-MoS 2) as synergistically signal-amplification platforms. The Au nanoparticles (AuNPs) were electrodeposited onto the surface of an indium tin oxide (ITO) electrode. After that, the thiolate-modified cDNA, also known as capture DNA, was combined with the aptamer. Subsequently, photosensitized SG molecules and ce-MoS 2 nanomaterial were inserted into the groove of the resultant double-stranded DNA (dsDNA). The activation of the photocatalytic process upon exposure to light resulted in the generation of singlet oxygen. The singlet oxygen effectively split the dsDNA, resulting in significant enhancement in the current of [Fe(CN) 6 ]3-/4-. When the CAP was present, both SG molecules and ce-MoS 2 broke away from the dsDNA, which turned off the photosensitization response, leading to significant reduction in the current of [Fe(CN) 6 ]3-/4-. Under the optimal conditions, the aptasensor exhibited a linear relationship between the current of [Fe(CN) 6 ]3-/4- with logarithmic concentrations of CAP from 20 to 1000 nM, with a detection of limit (3 σ) of 3.391 nM. The aptasensor also demonstrated good selectivity towards CAP in the presence of interfering antibiotics, such as tetracycline, streptomycin, levofloxacin, ciprofloxacin, and sulfadimethoxine. Additionally, the results obtained from the analysis of natural water samples using the proposed aptasensor were consistent with the findings acquired through the use of a liquid chromatograph-mass spectrometer. Therefore, with its simplicity and high selectivity, this aptasensor can potentially detect alternative antibiotics in environmental water samples by replacing the aptamers based on photosensitization. [ABSTRACT FROM AUTHOR]

Literature proves that the direct detection of 1O2(1Δg) at the solid gas interface is systematically performed from its phosphorescence using high intensity excitation sources (i.e., lasers), which lead to quasi‐ubiquitous chemical problems, such as sensitizer degradation, and photophysical counter‐active issues such as ultrafast exciton migration, singlet‐singlet and triplet‐triplet annihilation, and thermally activated delayed fluorescence mediated by 1O2(1Δg). To avoid these inconveniences, low excitation intensity is required but leads to serious analytical challenges. The best practices to reliably detect 1O2(1Δg) phosphorescence at various interfaces using a standard excitation source and near‐IR detector. The two main practices consist in a gas purging test for reliable identification of 1O2(1Δg), and in a particularly fine optimization of the angle made by excitation beam versus substrate plane. These practices are applied to porphyrin sensitizers H2TPP and ZnTPP, either neat or physiosorbed on glass, quartz, paper and hospital bandages, graphene oxide (GO), and embedded inside electrospun polystyrene fibers and spin coated poly(methyl methacrylate) films. Porphyrin‐based metal‐organic framework PCN‐224, freshly activated, is also examined. [ABSTRACT FROM AUTHOR]

Cefadroxil is a widely used antibiotic with a low elimination efficiency in wastewater treatments plants, so it represents a contaminants of emerging concern that should be removed. The photosensitization process that involves natural pigments and visible sunlight can be offered as an environmentally friendly alternative to be considered for Cefadroxil degradation. In this investigation, we carried out a mechanistic and kinetic approach to Cefadroxil photodegradation sensitized by Riboflavin and Humic Acid, in individual and combined processes. Our experiments indicate that Cefadroxil is able to interact with the excited states of Riboflavin as well as with the photogenerated reactive oxygen species, with an important contribution of singlet oxygen. The antibiotic was less sensitive to the photodegradation in the presence of Humic Acids and in the mixture of Riboflavin and Humic Acids. Self-sensitization processes and internal filter effects are proposed as possible explanations for the observed phenomenon. The reaction between Cefadroxil and singlet oxygen showed a dependence with the pH of the medium, the photodegradation kinetic constants are greater at alkaline pH compared to neutral pH. The reaction is favored when the anionic species of the antibiotic is present. Microbiological tests on S. aureus indicated that the antibiotic reduce its antimicrobial activity as a consequence of the photooxidative process mediated by singlet oxygen. We believe that the results are relevant since, the sensitized photodegradation process could lead to the oxidation of Cefadroxil and to the progressive loss of its antimicrobial function, this fact could contribute to the decrease in the generation of bacterial multi-resistance to antibiotics in the environment. [ABSTRACT FROM AUTHOR]

To develop heavy‐atom‐free triplet photosensitizers (PSs) based photocatalysts, we designed and synthesized two BODIPY‐helicene dyes by fusing the BODIPY core and modified [5]helicene structures. These BODIPY‐helicenes structures are twisted and their twisting angles are increased by the developed synthetic method. The BODIPY‐helicenes have broad absorption bands over UV‐visible region with high triplet conversions and long triplet lifetimes as compared to planar BODIPY dye, PM567. Consequently, these dyes are also highly efficient in generating 1O2 by transferring their triplet energy to 3O2. All these are confirmed by dye‐sensitised photooxidation reaction, nanosecond transient absorption spectroscopy study, phosphorescence measurement and DFT calculations. Finally, photocatalytic activity of the highest 1O2 generating BODIPY‐helicene (4 b) was checked. 4 b is highly efficient in photocatalytic oxidative coupling of differently substituted amines through aerobatic oxidation using 1O2 generated by its photosensitization. It is also highly efficient photocatalyst for aerobatic oxidation of sulfides to sulfoxides. Importantly, the photocatalyst could be quantitatively recovered and reused for several cycles. All these results confirmed the potential use of the BODIPY‐helicenes as PSs for photocatalytic organic reactions and the design strategy will be useful for the future development of heavy‐atom‐free photocatalyst. [ABSTRACT FROM AUTHOR]

Metal nanoclusters, due to their unique photophysical properties, exhibit tremendous potential applications in the biomedical fields of biosensing, bioimaging, and photodynamic and photothermal therapies. This review systematically discusses the photoreactive behavior and application progress of metal nanoclusters in biomedical diagnostics and treatment, especially the electronic behavior after photosensitization treatment and their roles in various biomedical applications. Initially, the review introduces the electronic transition processes of metal nanoclusters after absorbing light energy, along with their applications in biosensing and imaging. Subsequently, the review analyzes the mechanisms of action of metal nanoclusters in photodynamic and photothermal therapies. Lastly, the review proposes the prospects and challenges of metal nanoclusters in biomedical applications, with the hope of providing a reference for further research and application of metal nanocluster materials. [ABSTRACT FROM AUTHOR]

Dicarbonyl[10,10‐dimethyl‐5,15‐bis(pentafluorophenyl)biladiene]ruthenium(II), [Ru(C33H16F10N4)(CO)2] or Ru(CO)2[DMBil1], is the first reported ruthenium(II) cis‐dicarbonyl tetrapyrrole complex. The neutral complex sports two carbonyls and an oligotetrapyrrolic biladiene ligand. Notably, the biladiene adopts a coordination geometry that is well distorted from square planar and much more closely approximates a seesaw arrangement. Accordingly, Ru(CO)2[DMBil1] is not only the first ruthenium cis‐dicarbonyl with a tetrapyrrole ligand, but also the first metal biladiene complex in which the tetrapyrrole does not adopt a (pseudo‐)square‐planar coordination geometry. Ru(CO)2[DMBil1] is weakly luminescent, displaying λem = 552 nm upon excitation at λex = 500 nm, supports two reversible 1 e− reductions at −1.45 and −1.73 V (versus Fc+/Fc), and has significant absorption features at 481 and 531 nm, suggesting suitability for photocatalytic and photosensitization applications. While the structure of Ru(CO)2[DMBil1] was initially determined by X‐ray diffraction, a traditionally acceptable quality structure could not be obtained (despite multiple attempts) because of consistently poor crystal quality. An independent structure obtained from electron diffraction experiments corroborates the structure of this unusual biladiene complex. [ABSTRACT FROM AUTHOR]

This review article is aimed at providing updated information on the contribution of immediate and delayed oxidative reactions to the photo‐induced damage to cellular DNA/skin under exposure to UVB/UVA radiations and visible light. Low‐intensity UVC and UVB radiations that operate predominantly through direct excitation of the nucleobases are very poor oxidizing agents giving rise to very low amounts of 8‐oxo‐7,8‐dihydroguanine and DNA strand breaks with respect to the overwhelming bipyrimidine dimeric photoproducts. The importance of these two classes of oxidatively generated damage to DNA significantly increases together with a smaller contribution of oxidized pyrimidine bases upon UVA irradiation. This is rationalized in terms of sensitized photooxidation reactions predominantly mediated by singlet oxygen together with a small contribution of hydroxyl radical that appear to also be implicated in the photodynamic effects of the blue light component of visible light. Chemiexcitation‐mediated formation of "dark" cyclobutane pyrimidine dimers in UVA‐irradiated melanocytes is a recent major discovery that implicates in the initial stage, a delayed generation of reactive oxygen and nitrogen species giving rise to triplet excited carbonyl intermediate and possibly singlet oxygen. High‐intensity UVC nanosecond laser radiation constitutes a suitable source of light to generate pyrimidine and purine radical cations in cellular DNA via efficient biphotonic ionization. [ABSTRACT FROM AUTHOR]

• RSM was used for inactivation efficiency against two fungal species of tomatoes. • EO, UV and their combination were used and compared for tomatoes conservation. • The combined EO and UVC showed the best antifungal activity than other treatments. • Photosensitization of tomatoes preserved their quality attributes during 7 days. This study aims to investigate the antifungal activities of thyme essential oils mediated photosensitization for extending the shelf life and preserving the quality of fresh tomatoes. Contrary to Alternaria alternata and Botrytis cinerea , photosynthetization was proven to display the best antifungal activity, with a survival percentage of about 12 and 17% respectively. However, UV-C showed the least effectiveness, with survival rates of 33 and 32%, respectively, after 20 min of irradiation time. In addition, a central composite design (CCD) was employed, incorporating five levels and two independent variables: irradiation time and TEO concentration. This design aimed to assess the survival percentage of two fungal species, Alternaria. Alternata and Botrytis Cinerea. The obtained results indicated that the irradiation time significantly influenced the survival percentage of both tested fungal species. Interestingly, fresh tomato fruits were stored at 22 °°C with a relative humidity of 65 ± 5 % for 7 days and subsequently divided into four lots: control tomatoes, tomatoes treated only with UV-C irradiation at 10 min, tomatoes treated only with TEO at 55 µg/mL and photosynthesized tomatoes treated with both TEO and UV-C irradiations. The changes in the chemical properties of tomato, including pH, titratableacidity (TA), total soluble solids (TSS), texture and color, were analyzed, along with sensory evaluations. Chemical quality indicators like total soluble solids were significantly affected by storage time. Notably, in tomatoes treated with photosensitization, the TSS was lower (5 ± 0.05) compared to control tomatoes (5.6 ± 0.01) stored at 22 °C. Besides, the test of TEO based- photosensitization on tomatoes artificially inoculated with B. cinerea and A. alternata showed statistically significant delay in lesion diameter (1.5 cm ± 0.115) compared to the untreated group (3.5 cm ±0.15) at (p < 0.05). Subsequently, the combination of UV and TEO exhibited antifungal efficacy in tomato fruits, suggesting their potential as natural preservatives. [ABSTRACT FROM AUTHOR]

Novel far-red sensitive symmetric squaraine (SQ) dyes with terminal alkyl chain modifications were designed, synthesized, and characterized, aiming towards imparting multifunctionalities such as photosensitization, dye aggregation prevention, and source of electrolyte components. The dye sensitizer SQ-80 with alkyl chain terminal modifications consisting of 1-methylimidazolium iodide was designed and synthesized as a new dye sensitizer for DSSCs based on symmetric SQ-4 without any terminal modification used as reference. Upon adsorption on the mesoporous TiO2 surface, SQ-80 demonstrated reduced dye aggregation and stronger binding to the TiO2 surface, leading to enhanced durability of DSSCs. Apart from the most common photosensitization behavior, the newly designed dye demonstrated multifunctionalities such as aggregation prevention and electrolyte functionality, utilizing iodine-based redox electrolytes in the presence and absence of I2 and LiI additives. In the absence of LiI and I2, a mixture of SQ-77 with alkyl chain terminal modifications consisting of iodide and SQ-80 demonstrated a photoconversion efficiency of 1.54% under simulated solar irradiation, which was about six times higher compared with the reference dye SQ-4 (0.24%) (having no alkyl chain terminal modification). [ABSTRACT FROM AUTHOR]

Recently, development of new photosensitizing agents for the potential application in photodynamic therapy has gain considerable attention. Porphyrin a highly conjugated macrocyclic organic system with high molar absorption coefficient is considered suitable candidate for development of new photosensitizing agent. Therefore, a novel Azido-β-D-lactosylated zinc (II) tetraphenyl porphyrin was synthesized by four reactions steps. The molecular structures of the synthesized compounds were characterized by IR, 1H-NMR and UV--Vis spectroscopy. The water solubility properties of target compound were studied by UV--Vis spectroscopy in mixed water/DMSO mixed solvent system with different range of water contents. The water content in DMSO ranges from 10% to 100% (v/v). When the water contents increase to 20% intensity of the Soret band gradually decreases with an increasing water-content up to 100% attributed to the solubility of the compound in water. The water solubiliy properties of the porphyrin carbohydrate conjugate enhances its potential application in photodynamic therapy. [ABSTRACT FROM AUTHOR]

In recent decades, the rising wastewater output from industrial pollution has inflicted severe harm on both surface and groundwater, leading to substantial environmental damage. The elimination of harmful, toxic materials and wastewater remediation are pressing global concerns and pose a formidable challenge for scientists worldwide. Heterogeneous photocatalysis has been recognized as a promising, effective, energy-free, and eco-friendly process capable of completely degrading various organic pollutants. Finding a material that simultaneously satisfies various thermodynamic and kinetic criteria, coupled with good thermal- and photo-stability, is a challenging task necessitating the modification of existing materials or the synthesis of new ones to meet the required standards. This present study comprehensibly elaborates on different approaches to the modification of various photocatalytic systems, both organic and inorganic, in order to obtain more efficient and feasible catalysts for practical applications. In addition, the current status of the application of photocatalysts in dye wastewater treatment is summarized, projecting the future direction for wastewater management by photocatalytic processes. [ABSTRACT FROM AUTHOR]

Photoallergic contact dermatitis is a skin disease caused by combined exposure to photoreactive chemicals and sunlight. Exposure to allergens and the risk of skin sensitization is an essential regulatory issue within the industry. Yet, only few non‐validated assays for photoallergy assessment exist as the pathogenesis is not fully deciphered. Improving such assays and/or developing new ones require an understanding of the chemical mechanisms involved. The first key event in the photosensitization process, namely chemical binding of the photoallergen to endogenous proteins, is thought to proceed via photo‐mediated radicals arising from the photoallergen. Moreover, the mechanism of action of these radicals if formed in the epidermis is not known and far from being unraveled. We present here an original proof‐of‐concept methodology to probe radical generation from allergens in contact with photoexposed skin, using electron paramagnetic resonance and spin trapping in a reconstructed human epidermis model mimicking real‐life exposure scenarios. [ABSTRACT FROM AUTHOR]

Unprecedented experimental evidence shows that gaseous singlet oxygen (1O2) acts as an emissive ligand following collisional photosensitization. This evidence was obtained by monitoring 1O2 phosphorescence intensity at ≈1275–1280 nm and the excited state lifetime of singlet oxygen generated by known tetraphenylporphyrin photosensitizers, while varying the atmospheric environment. [ABSTRACT FROM AUTHOR]

TiO2‐based composite photocatalysts are currently being explored to address concerns intrinsic to TiO2, specifically high charge carrier recombination and UV light activation. Among various materials utilized for composite formation, carbon nanomaterials stand out due to their high electron conductivity, charge storage, photosensitization, and surface properties. However, high carbon content in composites has been shown to reduce performance with potential toxicity concerns. To harness the diverse properties of carbon nanomaterials in a single composite while optimizing the carbon content below 1% by weight, multi‐walled carbon nanotubes (MWCNT)/TiO2 sensitized by carbon nanodots (CND) are synthesized. The heterojunction formed between MWCNTs and TiO2 in the binary composite reduced the charge carrier recombination rate compared to TiO2. The addition of CNDs to MWCNT/TiO2 induced visible light absorbance of the resulting ternary composite, due to the forbidden electron transitions undergone in CND aggregates. CND/MWCNT/TiO2 exhibited a fivefold and 1.6‐fold increase in photocatalytic degradation of acid orange 7 and tetracycline under visible light compared to TiO2. This enhancement is attributed to the photosensitizing property of CNDs working in synergy with the charge storage ability of MWCNTs. A plausible charge transfer pathway for the activity of CND/MWCNT/TiO2 is proposed. [ABSTRACT FROM AUTHOR]

Herein, we report a novel flavin analogue as singular chemical component for lysosome bioimaging, and inherited photosensitizer capability of the flavin core was demonstrated as a promising candidate for photodynamic therapy (PDT) application. Fine‐tuning the flavin core with the incorporation of methoxy naphthyl appendage provides an appropriate chemical design, thereby offering photostability, selectivity, and lysosomal colocalization, along with the aggregation‐induced emissive nature, making it suitable for lysosomal bioimaging applications. Additionally, photosensitization capability of the flavin core with photostable nature of the synthesized analogue has shown remarkable capacity for generating reactive oxygen species (ROS) within cells, making it a promising candidate for photodynamic therapy (PDT) application. [ABSTRACT FROM AUTHOR]

Singlet oxygen is a powerful oxidant used in various applications, such as organic synthesis, medicine, and environmental remediation. Organic and inorganic photosensitizers are commonly used to generate this reactive species through energy transfer with the triplet ground state of oxygen. We describe here a series of novel benzophenazine derivatives as a promising class of photosensitizers for singlet oxygen photosensitization. In this study, we investigated the structure‐activity relationship of these benzophenazine derivatives. Akin to a molecular compass, the southern fragment was first functionalized with either aromatic tertiary amines, alkyl tertiary amines, aromatic sulfur groups, alkyl sulfur groups, or cyclic ethers. Enhanced photophysical properties (in terms of triplet excited‐state lifetime, absorption wavelength, triplet state energy, and O2 quenching capabilities) were obtained with cyclic ether and sulfur groups. Conversely, the presence of an amine moiety was detrimental to the photocatalysts. The western and northern fragments were also investigated and slightly undesirable to negligible changes in photophysical properties were observed. The most promising candidate was then immobilized on silica nanoparticles and its photoactivity was evaluated in the citronellol photooxidation reaction. A high NMR yield of 97 % in desired product was obtained, with only a slight decrease over several recycling runs (85 % in the fourth run). These results provide insights into the design of efficient photosensitizers for singlet oxygen generation and the development of heterogeneous systems. [ABSTRACT FROM AUTHOR]

In photocatalysis, the resulted heat by the relaxation of most of incident light no longer acts as the industrially favorite driving force back to the target photo‐reaction due to more or less the negative relation between photocatalytic efficiency and temperature. Here, we reported a visible light‐sensitized protocol that completely reversed the negatively temperature‐dependent efficiency in photo‐driven CO2 methanation with saturated water vapor. Uniform Pt/N‐TiO2/PDI self‐assembly material decisively injects the excited electron of PDI sensitizer into N‐TiO2 forming Ti−H hydride which is crucially temperature‐dependent nucleophilic species to dominate CO2 methanation, rather than conventionally separated and trapped electrons on the conductor band. Meanwhile, the ternary composite lifts itself temperature from room temperature to 305.2 °C within 400 s only by the failure excitation upon simulated sunlight of 2.5 W/cm2, and smoothly achieves CO2 methanation with a record number of 4.98 mmol g−1 h−1 rate, compared to less than 0.02 mol g−1 h−1 at classic Pt/N‐TiO2/UV photocatalysis without PDI sensitization. This approach can reuse ~53.9 % of the relaxed heat energy from the incident light thereby allow high‐intensity incident light as strong as possible within a flowing photo‐reactor, opening the most likely gateways to industrialization. [ABSTRACT FROM AUTHOR]

Singlet oxygen (1O2) is known to have antibacterial activity; however, production can involve complex processes with expensive chemical precursors and/or significant energy input. Recent studies have confirmed the generation of 1O2 through the activation of photosensitizer molecules (PSs) with visible light in the presence of oxygen. Given the increase in the incidence of foodborne diseases associated with cross-contamination in food-processing industries, which is becoming a major concern, food-safe additives, such as chlorophyllins, have been studied for their ability to act as PSs. The fluorescent probe Singlet Oxygen Sensor Green (SOSG®) was used to estimate 1O2 formation upon the irradiation of traditional PSs (rose bengal (RB), chlorin 6 (ce6)) and novel chlorophyllins, sodium magnesium (NaChl) and sodium copper (NaCuChl), with both simulated-solar and visible light. NaChl gave rise to a similar 1O2 production rate when compared to RB and ce6. Basic mixing was shown to introduce sufficient oxygen to the PS solutions, preventing the limitation of the 1O2 production rate. The NaChl-based inactivation of Gram-positive S. aureus and Gram-negative E. coli was demonstrated with a 5-log reduction with UV–Vis light. The NaChl-based inactivation of Gram-positive S. aureus was accomplished with a 2-log reduction after 105 min of visible-light irradiation and a 3-log reduction following 150 min of exposure from an initial viable bacterial concentration of 106 CFU mL−1. CHS-NaChl-based photosensitization under visible light enhanced Gram-negative E. coli inactivation and provided a strong bacteriostatic effect preventing E. coli proliferation. The difference in the ability of NaChl and CHS-NaChl complexes to inactivate Gram-positive and Gram-negative bacteria was confirmed to result from the cell wall structure, which impacted PS–bacteria attachment and therefore the production of localized singlet oxygen. [ABSTRACT FROM AUTHOR]

Diaryliodonium salts (Ar2I+X−) are used as a photosensitive initiator that generates acid or radical species by ultraviolet light irradiation. Recently, sensitization of Ar2I+X− has gained importance owing to the escalating demand for high‐sensitive initiators with longer wavelength absorption such as 365 and 436 nm. However, the mechanism of photolysis of Ar2I+X− has not been strictly elucidated. This paper shows discussions of the details of its mechanism. Herein, we analyzed the photosensitization of Ar2I+X− with 2–isopropylthioxanthone (ITX) based on transient absorption techniques. As a result, it was revealed that electron transfer occurred from a triplet excited state of ITX to Ar2I+X− with an electron transfer rate constant of 4.2 × 109 s−1. Furthermore, high performance liquid chromatography measurements found the quantum yield of the photolysis was determined to be 0.48. [ABSTRACT FROM AUTHOR]

The construction of secondary building units (SBUs) in versatile metal–organic frameworks (MOFs) represents a promising method for developing multi‐functional materials, especially for improving their sensitizing ability. Herein, we developed a dual small molecules auxiliary strategy to construct a high‐nuclear transition‐metal‐based UiO‐architecture Co16‐MOF‐BDC with visible‐light‐absorbing capacity. Remarkably, the N3− molecule in hexadecameric cobalt azide SBU offers novel modification sites to precise bonding of strong visible‐light‐absorbing chromophores via click reaction. The resulting Bodipy@Co16‐MOF‐BDC exhibits extremely high performance for oxidative coupling benzylamine (~100 % yield) via both energy and electron transfer processes, which is much superior to that of Co16‐MOF‐BDC (31.5 %) and Carboxyl @Co16‐MOF‐BDC (37.5 %). Systematic investigations reveal that the advantages of Bodipy@Co16‐MOF‐BDC in dual light‐absorbing channels, robust bonding between Bodipy/Co16 clusters and efficient electron‐hole separation can greatly boost photosynthesis. This work provides an ideal molecular platform for synergy between photosensitizing MOFs and chromophores by constructing high‐nuclear transition‐metal‐based SBUs with surface‐modifiable small molecules. [ABSTRACT FROM AUTHOR]

Introduction and aim. Vitiligo is a chronic skin disease characterized by progressive loss of melanocytes. Various treatment options have been developed to manage vitiligo, however, phototherapy has emerged as one of the most effective treatment options. Therefore, this review has been written to examine the mechanisms of this particular treatment approach and its optimal implementation. Material and methods. A review of the literature regarding combination of word vitiligo with the following: psoralen ultraviolet A (PUVA), narrowband ultraviolet B (NB-UVB) and excimer laser (EL) was performed using the PubMed database. Analysis of the literature. NB-UVB has demonstrated safety and efficacy in stimulating melanocyte proliferation and melanin synthesis, making it an attractive treatment option for both localized and generalized vitiligo. PUVA therapy, combining psoralen photosensitization with UVA irradiation, has shown remarkable efficacy in repigmentation, particularly in refractory or extensive vitiligo. However, because of possible side effects, it is not recommended as a first line phototherapy. With its targeted and precise approach, EL offers a localized treatment and has produced impressive results in localized and segmented vitiligo. Conclusion. Despite limitations, phototherapy continues to evolve, offering hope for individuals with vitiligo. Further research and advancements in treatment protocols are needed. [ABSTRACT FROM AUTHOR]

As this is a meta-study, we examined whether plant species diversity in the feed and the possibility of feed choice would influence the number of cases of photosensitization in farm animals. We evaluated 110 scientific references which described 172 cases of photosensitization worldwide, mainly in husbandry animals between 1926 and 2022. More than 50% of the cases occurred in South America and Australia. Among the animal species, sheep and cattle were statistically overrepresented. A total of 35 organisms were revealed to be phototoxic: 24 herbs, 2 grasses, 7 woody species, and 2 kinds of fungi. Animals developed mainly secondary photosensitization due to fresh feed (71.8%) of normal quality (88.1%), indicating that the phototoxic agents are from liver-toxic plants such as the grass Brachiaria and the herb Froelichia. Horses fell ill chiefly with primary photosensitization due to directly acting phototoxic agents of plant species such as the herbs Medicago and Pastinaca, both in fresh and conserved feed. Goats manage to avoid phototoxic plants under both high and low feed diversity if they still have free choice between plant species. High feed diversity reduced the incidence 2.4-fold, while enabled selection possibility even reduced it 7.5-fold. Since the lack of choice between forage plants was revealed to be the main cause of photosensitization, this knowledge could be used to prevent the disease in livestock. [ABSTRACT FROM AUTHOR]

A mild protocol for hydroacylation of enones through photosensitization of acyl silanes with thioxanthone under blue light (455 nm) irradiation is reported. A Brønsted acid is used as a cocatalyst in the reaction. The versatility of the method is demonstrated through inter‐ and intramolecular hydroacylation reaction. The hydroacylation product is applied for synthesizing an anti‐HCV agent. Mechanistic insights are also provided through control experiments. [ABSTRACT FROM AUTHOR]

Heterogenization of Eosin Y by 3D‐printing and its application in photocatalysis are reported. The approach allows a fine tuning of the photocatalyst morphology and its rapid preparation. Photocatalytic activity was evaluated through model organic reactions involving oxidation, reduction, and photosensitization pathways. The efficiency, recyclability and stability of 3D printed EY is remarkable paving the way to new generation of heterogeneous photocatalysts with a perfect control of their shape and adaptable to any photoreactors. [ABSTRACT FROM AUTHOR]

The effective utilization of light is crucial in the use of the solar energy for CO2 conversion into valuable fuels and chemicals, in which improving the photocatalytic materials' capacity to absorb light is a key. Herein, a 2D copper–porphyrin metal−organic framework (MOF)‐photosensitized titania, TiO2/Zn–CuTCPP, is reported, which can absorb wide range of light and photoreduce CO2 with high efficiency under full spectrum irradiation. Fluorescence spectral analysis elucidates the relationship between the photocatalytic activity and the electron–hole separation efficiency. In addition, mechanistic information obtained from electron paramagnetic resonance and in situ infrared analyses demonstrates that the presence of Cu–N4 site in the MOF structure is conducive to the generation of hydrogen free radicals (•H), which plays a key role in the formation of intermediates, thus facilitating the hydrogenation in the reaction process. Consequently, TiO2/Zn–CuTCPP significantly enhances the photocatalytic conversion of CO2 into CH4 with a yield 14 times higher than that of P25. [ABSTRACT FROM AUTHOR]

In water, N,N′-diarylpyridinium thiazolo[5,4-d]thiazole guests (G1–G3) were encapsulated by cucurbit[8]uril (Q[8]) to construct Q[8]3/G2 complexes, in which the encapsulated G molecules exist as an exact face-to-face dimer. These complexation behaviors have been indicated by proton nuclear magnetic resonance (1H NMR) spectroscopy and isothermal titration calorimetry (ITC), and have been confirmed by X-ray single crystal structural analysis of Q[8]3/G22. While free guests G1–G3 have no ability to sensitize singlet oxygen, they all become effective singlet oxygen sensitizers when complexed with Q[8]. By irradiation of white light, Q[8]3/G2 complexes induced selective oxidation of aryl sulfide to aryl sulfoxide in good yields and selective oxidation of dimethyl sulfide (DMS) to dimethyl sulfoxide (DMSO) in excellent yields without over-oxidation to dimethyl sulfone (DMSO2) even for elongated irradiation. High-yield photo-oxidation of DMS to DMSO2 was only achieved by irradiation of blue light in the presence of Q[8]3/G12, which was also effective in photobleaching of Rhodamine B in water. The higher photo-oxidation power of Q[8]3/G12 has been ascribed to an additional generation of reactive oxygen species besides singlet oxygen. [ABSTRACT FROM AUTHOR]

Photoallergy, a unique form of skin sensitization induced by specific compounds under ultraviolet irradiation, has traditionally been investigated using animals. However, the prohibition of animal testing for the assessment of cosmetic ingredients in Europe and other countries underscores the necessity for in vitro or in silico alternative methods. Currently, there are no validated methods for assessing photoallergy or photosensitization, presenting a significant challenge in the development of new cosmetic ingredients. This review examines the landscape of alternative methods for detecting photosensitization, emphasizing recent publications, and considering the underlying principles of the different proposed assays. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has been a topic of interest since the first report in 1900 but has yet to become a 'mainstream' treatment protocol in the medical field. There are clear indications for which PDT might be the 'method of choice', but it is unlikely that there will be protocols for the treatment of systemic disease. This report discusses recent developments for promoting PDT efficacy, in the context of what is already known. Factors that can limit the scope of these applications are also indicated. Among the more interesting of these developments is the use of formulation techniques to target specific organelles for photodamage. This can enhance responses to PDT and circumvent situations where an impaired death pathway interferes with PDT efficacy. [ABSTRACT FROM AUTHOR]

In the continuation of previous studies on carbon‐rich meso‐tetraarylporphyrins featuring 2,7‐fluorene units at their periphery, the effect of changing the peripheral dendritic arms for linear arms on their oxygen‐photosensitizing ability, their fluorescence and their two‐photon absorption (2PA) properties is now analyzed. Thus, starburst porphyrins possessing up to twenty conjugated fluorenyl units were isolated and studied. More precisely, a series of five new free‐base porphyrins featuring fully conjugated arms incorporating an increasing number of fluorenyl groups connected via 1,2‐alkenyl spacers were synthesized, along with their Zn(II) complexes. Upon excitation in the arm‐centred π‐π* absorption band, an efficient energy transfer takes place from the peripheral fluorenyl units to the central porphyrin core, leading to intense red‐light emission and oxygen photosensitization by the latter. More interestingly, while the linear optical properties of these porphyrins were only slightly improved compared to those of their dendrimer analogues for photodynamic therapy (PDT) or fluorescence imaging, their 2PA cross‐sections were much more significantly boosted, evidencing the key role played by different structures on nonlinear optical properties. Finally, by comparison with other porphyrin‐based two‐photon photosensitizers reported in the literature, we show that these new "semi‐disconnected" starburst systems exhibit a remarkable trade‐off between intrinsic 2PA, fluorescence and oxygen photosensitization. [ABSTRACT FROM AUTHOR]

A visible light induced electrocyclization for synthesizing dihydrophenathrenes is reported. The readily available organic photocatalyst 4‐CzIPN enables α‐addition to enones in good yield (up to 95 %). This 6π‐electrocyclization is proposed to proceed through a photosensitization pathway and it avoids the use of high energy UV light. [ABSTRACT FROM AUTHOR]

Measurement of photosensitized luminescence of singlet oxygen has been applied to studies of singlet oxygen generation and quenching by C40 carotenoids (neurosporene, lycopene, rhodopin, and spirilloxanthin) with long chain of conjugated double bonds (CDB) using hexafluorobenzene as a solvent. It has been found that neurosporene, lycopene, and rhodopin are capable of the low efficient singlet oxygen generation in aerated solutions upon photoexcitation in the spectral region of their main absorption maxima. The quantum yield of this process was estimated to be (1.5–3.0) × 10−2. This value is near the singlet oxygen yields in solutions of ζ-carotene (7 CDB) and phytoene (3 CDB) and many-fold smaller than in solutions of phytofluene (5 CDB) (Ashikhmin et al. Biochemistry (Mosc) 85:773–780, https://doi.org/10.1134/S0006297920070056, 2020, Biochemistry (Mosc) 87:1169–1178, 2022, https://doi.org/10.1134/S00062979221001082022). Photogeneration of singlet oxygen was not observed in spirilloxanthin solutions. A correlation was found between the singlet oxygen yields and the quantum yields and lifetimes of the fluorescence of the carotenoid molecules. All carotenoids were shown to be strong physical quenchers of singlet oxygen. The rate constants of 1O2 quenching by the carotenoids with long chain of CDB (9–13) were close to the rate constant of the diffusion-limited reactions ≈1010 M−1 s−1, being many-fold greater than the rate constants of 1O2 quenching by the carotenoids with the short chain of CDB (3–7) phytoene, phytofluene, and ζ-carotene studied in prior papers of our group (Ashikhmin et al. 2020, 2022). To our knowledge, the quenching rate constants of rhodopin and spirilloxanthin have been obtained in this paper for the first time. The mechanisms of 1O2 photogeneration by carotenoids in solution and in the LH2 complexes of photosynthetic cells, as well as the efficiencies of their protective action are discussed. [ABSTRACT FROM AUTHOR]

Abstract TiO2‐based composite photocatalysts are currently being explored to address concerns intrinsic to TiO2, specifically high charge carrier recombination and UV light activation. Among various materials utilized for composite formation, carbon nanomaterials stand out due to their high electron conductivity, charge storage, photosensitization, and surface properties. However, high carbon content in composites has been shown to reduce performance with potential toxicity concerns. To harness the diverse properties of carbon nanomaterials in a single composite while optimizing the carbon content below 1% by weight, multi‐walled carbon nanotubes (MWCNT)/TiO2 sensitized by carbon nanodots (CND) are synthesized. The heterojunction formed between MWCNTs and TiO2 in the binary composite reduced the charge carrier recombination rate compared to TiO2. The addition of CNDs to MWCNT/TiO2 induced visible light absorbance of the resulting ternary composite, due to the forbidden electron transitions undergone in CND aggregates. CND/MWCNT/TiO2 exhibited a fivefold and 1.6‐fold increase in photocatalytic degradation of acid orange 7 and tetracycline under visible light compared to TiO2. This enhancement is attributed to the photosensitizing property of CNDs working in synergy with the charge storage ability of MWCNTs. A plausible charge transfer pathway for the activity of CND/MWCNT/TiO2 is proposed.

Carbon quantum dots (CQDs) are an emerging class of carbon-based nanomaterials. CQDs are receiving considerable interest in biomedical applications due to their low toxicity, stability profile, efficient surface tailorability, aqueous solubility, diverse functionality, biocompatibility, and size-tunable emission when compared to other conventional carbon quantum dots (CDs) of group II, III, IV & V. Improved photodynamic treatment, photosensitization, bioimaging, targeted drug delivery, fluorescent marker for disease-detection, cell tracking, and biosensors are made possible by the presence of diverse functional groups on the surface of CQDs, such as thiol, carboxyl, hydroxyl, etc. This article gives thorough understanding of CQDs for drug delivery applications by describing their origin and rationale. In addition, the in-vivo characteristics of CQDs are also examined in an initiative to strengthen the argument for CQDs as powerful drug delivery vehicles.

Carbon–semiconductor hybrid quantum dots are classical carbon dots with core carbon nanoparticles doped with a selected nanoscale semiconductor. Specifically, on those with the nanoscale TiO2 doping, denoted as CTiO2-Dots, their synthesis and thorough characterization were reported previously. In this work, the CTiO2-Dots were evaluated for their visible light-activated antibacterial function, with the results showing the effective killing of not only Gram-positive but also the generally more resistant Gram-negative bacteria. The hybrid dots are clearly more potent antibacterial agents than their neat carbon dot counterparts. Mechanistically, the higher antibacterial performance of the CTiO2-Dots is attributed to their superior photoexcited state properties, which are reflected by the observed much brighter fluorescence emissions. Also considered and discussed is the possibility of additional contributions to the antibacterial activities due to the photosensitization of the nanoscale TiO2 by its doped core carbon nanoparticles. [ABSTRACT FROM AUTHOR]

Carbazole is a heterocyclic motif that can be found in a diverse array of natural and unnatural products displaying a wide range of biological and physiological properties. Furthermore, this heterocycle is part of electronic materials like photoconducting polymers and organic optoelectronic materials owing to its excellent photophysical characteristics. Consequently, the development of synthetic strategies for carbazole scaffolds holds potential significance in biological and material fields. In this regard, a variety of preparation methods has been developed to exploit their efficient and distinct formation of new C−C and C‐heteroatom bonds under mild conditions and enabling broad substrate diversity and functional group tolerance. Therefore, this review focuses on the synthesis of a set of carbazole derivatives describing a variety of methodologies that involve direct irradiation, photosensitization, photoredox, electrochemical and thermal cyclization reactions. [ABSTRACT FROM AUTHOR]

The Pauson-Khand reaction has in the past 50 years become one of the most common cycloaddition reactions in chemistry. Coupling two unsaturated bonds with carbon monoxide, the transformation remains limited to CO as a C1 building block. Herein we report analogous cycloaddition reactions with nitrenes as an N1 unit. The reaction of a nonconjugated diene with a nitrene precursor produces bicyclic bioisosteres of common saturated heterocycles such as piperidine, morpholine, and piperazine. Experimental and computational mechanistic studies support relaying of the diradical nature of triplet nitrene into the p-system. We showcase the reactionÕs utility in late-stage functionalization of drug compounds and discovery of soluble epoxide hydrolase inhibitors. [ABSTRACT FROM AUTHOR]

Fluorescent nucleobase and nucleic acid analogs are important tools in chemical and molecular biology as fluorescent labelling of nucleobases has applications in cellular imaging and anti-tumor activity. Boron-dipyrromethene (BODIPY) dyes exhibiting high brightness and good photostability are extensively used as fluorescent labelling agents and as type II photosensitizers for photodynamic therapy. Thus, the combination of nucleobases and BODIPY to obtain new compounds with both anti-tumor activity and fluorescent imaging functions is the focus of our research. We synthesized two new nucleobase analogs 1 and 2 by fusing the BODIPY core directly with uracil which resulted in favorable photophysical properties and high emission quantum efficiencies particularly in organic solvents. Further, we explored the newly synthesized derivatives, which possessed good singlet oxygen generation efficiencies and bio-compatibility, as potential PDT agents and our results show that they exhibit in vitro anti-tumor activities. [ABSTRACT FROM AUTHOR]

The feasibility of singlet fission (SF) in organic photosensitizers is investigated through spin-flip long-range corrected time-dependent density functional theory. This study focuses on four major organic photosensitizer molecules: benzophenone, boron-dipyrromethene, methylene blue, and rose bengal. Calculations demonstrate that all these molecules possess moderate π -stacking energies and closely-lying singlet (S) and quintet (triplet–triplet, TT) excitations, satisfying the essential conditions for SF: (1) Near-degenerate low-lying S and (TT) excitations with a significant S–T energy gap, and (2) Moderate π -stacking energy of chromophores, slightly higher than solvation energy, enabling dissociation for triplet-state chromophore generation. Moreover, based on the El-Sayed rule, intersystem crossing is found to simultaneously proceed at very slow rates in all these photosensitizers. This is attributed to the fact that the lowest singlet excitation of the monomers partly involves n π ∗ transitions alongside the main π π ∗ transitions. The proposed mechanisms are strongly substantiated by comparisons with experimental studies. [ABSTRACT FROM AUTHOR]

Photosensitization, occurring as a result of drug treatment, represents 8% of all drug-induced skin adverse reactions. The drug photosensitization reaction is unpredictable and every patient can be affected, as it can occur at any age and can be caused by numerous drugs. Currently, two types of photosensitization reactions are known, namely: phototoxic and photoallergic reactions. Phototoxicity reactions are manifested by a direct action of cellular destruction, are not immune-mediated, are dose-dependent, and can occur at first exposure in most individuals receiving photosensitizing drugs. Photoallergic reactions are immune-mediated, not dose-dependent, occur only in sensitized individuals, and are characterized by cross-reactions between related compounds. There are a lot of photosensitizing drugs such as: antibiotics, sulfanilamides, fluoroquinolones, nonsteroidal anti-inflammatory drugs, diuretics, hormonal contraceptives, retinoids, etc. Some drugs cause only one type of reaction, while others may cause both. In general, the prognosis of drug photosensitization reactions is a good one, if certain rules are followed, such as the use of protective creams, clothing and protective glasses together with the drugs, as well as the doctor’s supervision of the treatment evolution. [ABSTRACT FROM AUTHOR]

Highly emissive ternary Eu(III) complexes were synthesized with a tri-fluorinated β-diketone as principal ligand and heterocyclic aromatic compounds as ancillary ligands to assess their utility as an illuminating material for display devices and other optoelectronics. The general characterizations, regarding the coordinating facets of complexes were accomplished via various spectroscopic techniques. Thermal stability was investigated via TGA/DTA. Photophysical analysis was accomplished by PL studies, Band gap value, color parameters and J-O analysis. DFT calculations were performed adopting geometrically optimized structure of complexes. Superb thermal stability has been achieved in complexes, which decides their concrete candidature for display devices. The bright red luminescence of complexes is ascribed to 5D0 → 7F2 transition of Eu(III) ion. Colorimetric parameters unlocked the applicability of complexes as warm light source and J-O parameters adequately summarized the coordinating surrounding around the metal ion. Various radiative properties were also evaluated which suggested the prospective use of complexes in lasers and other optoelectronic devices. The band gap and Urbach band tail, procured from absorption spectra, revealed the semiconducting behavior of synthesized complexes. DFT studies rendered the energies of FMO and various other molecular parameters. It can be summarized from the photophysical and optical analysis of synthesized complexes that these complexes are virtuous luminescent materials and possess potentiality to be used in diverse domain of display devices. [ABSTRACT FROM AUTHOR]

Developing renewable means of activating molecules over traditional catalysts for C−C bond formation is desirable for industrial applications. Herein, we report a strategy to improve the efficiency of Pd nanoparticles (NPs) for the Suzuki cross‐coupling reactions by visible‐light irradiation using g‐C3N4 nanosheets (NSs) as photosensitizer. Pd NPs mounted on g‐C3N4 become electron‐rich under visible‐light due to generation of excited electrons in g‐C3N4 and thereby accelerate the rate‐determining step. Remarkable photocatalytic activity was accomplished utilizing Pd/g‐C3N4 for the Suzuki cross‐coupling reaction in environmentally benign aqueous settings under room temperature conditions. The activity remarkably improves (~2.5 times) upon light irradiation, yielding one of the highest known turnover frequencies (TOF) of 1858 h−1 and confirming the photosensitizer role of g‐C3N4. The TOF for coupling of aryl bromides is also significantly high (~356 h−1). We establish that the low‐energy/long‐lived excitons preferencially transfer to Pd, paving a way for rational designing photocatalysts for various C−C coupling reactions. [ABSTRACT FROM AUTHOR]

Structurally diversified diazoalkanes can be activated under red light irradiation relying on direct photolysis, photosensitization or photoredox catalysis. [ABSTRACT FROM AUTHOR]

A second generation of cyanine‐based near‐infrared photocatalysts has been developed to accelerate organic transformations. Cyanines were prepared and fully characterized prior to evaluation of their photocatalytic activities. Catalyst efficiency was determined by using two model oxidation and reduction reactions. For the aza‐Henry reaction, cyanines bearing an amino group on the heptamethine chain led to the best results. For trifluoromethylation, the stability of the photocatalyst was found to be the key parameter for efficient and rapid conversion. [ABSTRACT FROM AUTHOR]

This study focused on the solvothermal synthesis, characterization, and photocatalytic activities of two novel coordination polymers, namely [Zn(μ-HSeO3)2(bipy)]n (1) and [Zn(μ-HSeO3)2(phen)]n (2). These compounds represent the first organically linked ZnII hydrogenselenite coordination polymers. The synthesis of compounds 1 and 2 involved the addition of 2,2′-bipyridine and 1,10-phenanthroline, respectively, to SeO2 and ZnO in methanol as the solvent. The novel hydrogenselenite compounds were thoroughly characterized using spectroscopic and crystallographic methods. The photocatalytic solids (TiO2-1A and TiO2-2A) were prepared by immobilizing compounds 1–2 onto TiO2 through the sol–gel approach. These photocatalysts were then evaluated for hydrogen evolution via water splitting using a 300 W Hg/Xe lamp as the irradiation source. Among the newly synthesized photocatalytic materials, TiO2-1A demonstrated auspicious photocatalytic performance for hydrogen gas production. Its catalytic activity overcame the observed for the pure solid support TiO2 and Degussa P25 (commercial titania), making compound 1 a particularly attractive TiO2 photosensitizer. Additionally, TiO2-1A exhibited superior photocatalytic activity compared to TiO2-2A. The latter performed better than freshly prepared TiO2, approaching that of Degussa P25. These findings highlight the potential of compound 1 as an effective photosensitizer for TiO2-based photocatalysis, making it a promising candidate for applications in clean energy generation, specifically in hydrogen production by water splitting. [ABSTRACT FROM AUTHOR]

Photosensitization of proteins mediated by chromophores is a mechanism commonly employed by nature and mimicked in a broad array of laboratory research and applications. Nature has evolved specialized complexes of proteins and photosensitizers (PS) that assemble to form photoreceptor proteins (PRP). These are used by many organisms in diverse processes, such as energy conversion, protection against photodamage, etc. The same concept has been used in laboratory settings for many applications, such as the stimulation of neurons or the selective depletion of proteins in a signaling pathway. A key issue in laboratory settings has been the relationship between the photooxidation of proteins and conformational changes in host proteins. For several years, we have been interested in creating non-native PRP using porphyrin PS. In this study, we investigated the self-assembled complex between zinc protoporphyrin IX (ZnPPIX) and bovine β-lactoglobulin (BLG) as a model of non-native PRP. Since BLG undergoes a significant conformational transition near physiological pH, the study was carried out at acidic (pH 5) and alkaline (pH 9) conditions where the two conformations are respectively prevalent. We employed a series of steady-state and time-resolved optical spectroscopies as well as gel electrophoresis to experimentally characterize the photosensitization mechanisms and their effect on the host protein. Our results show that ZnPPIX prompts light-dependent modifications of BLG, which appear to be much more significant at alkaline pH. The modifications seem to be driven by photooxidation of amino acid residues that do not lead to the formation of cross-links or protein fragmentation. [ABSTRACT FROM AUTHOR]