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Noninvasive sonodynamic therapy (SDT) shows promise for brain glioma treatment due to deep tissue‐penetrating capabilities (>10 cm) of ultrasound and high spatial resolutions. Yet, this technique is hindered by inefficient production of reactive oxygen species (ROS), resulting from the hypoxic tumor microenvironment (TME), high level of ROS scavenger glutathione (GSH), and the inability to visualize glioma in vivo for precise treatment management and monitoring in current sonosentizers. To address these challenges, we fabricated a core‐shell heterostructure sonosensitizer (labeled as DFM), in which meso‐tetra (4‐carboxyphenyl) porphine (TCPP) porphyrin metal‐organic frameworks (MOF, PCN‐224(Fe)) serve as a porous shell to contain approved chemotherapeutics sorafenib (SRF) to effectively inhibit GSH synthesis, while NaErF4:Yb@NaLuF4 nanoparticles as the core provide TME‐responsive NIR IIb (≈1500–1800 nm) luminescence at 1525 for precise optical imaging. Coordination of Fe3+ into the macrocycle of TCPP at the MOFs shell is found to, besides triggering ferroptosis, reduce TCPP phosphorescence (23% decrease) and increase the triplet state (T1) oxygen quenching, substantially promoting the singlet oxygen generation (2.6‐fold increase). Furthermore, GSH in TME facilitates the reduction of Fe3+ to Fe2+, thereby eliminating the luminescence quenching of Fe3+ and augmenting the NIR IIb luminescence of Er3+ (5‐fold increase) for nanoagents accumulation imaging in intracranial glioma, realizing dynamical monitoring of SDT processes. Compared to control groups, in vitro and in vivo experiments confirm the effective ROS generation and results in a 6‐fold volume reduction of brain gliomas, reaching a survival rate of 80% at 30 days posttreatment. [ABSTRACT FROM AUTHOR]

Phosphorescence spectroscopy of singlet oxygen [=O2(1Δg)] was applied to study the solvation properties of small solute molecule, O2, in ionic liquids. Unlike conventional molecular solvents, the spectral red shift of the O2(1Δg) phosphorescence in ionic liquids from the gas phase was found to depend not only on the refractive index of solvents but also on the vdW volume of anions. This unusual spectral shift of the O2(1Δg) luminescence is interpreted by considering the size of solvation cavities in voids, which is estimated by analyzing the free volume in ionic liquids. These results suggest the potential of the O2(1Δg) phosphorescence spectral shift measurement in the study of molecular-scale voids in ionic liquids. [ABSTRACT FROM AUTHOR]

Disulfide bonds are critical structural elements in proteins and stabilize folded structures. Modification of these linkages is associated with a loss of structure and function. Previous studies have reported large variations in the rate of disulfide oxidation by hypohalous acids, due to stabilization of reaction intermediates. In this study we hypothesized that considerable variation (and hence selective oxidation) would occur with singlet oxygen (1O 2), a key intermediate in photo-oxidation reactions. The kinetics of disulfide-mediated 1O 2 removal were monitored using the time-resolved 1270 nm phosphorescence of 1O 2. Stern-Volmer plots of these data showed a large variation (∼103) in the quenching rate constants k q (from 2 × 107 for α-lipoic acid to 3.6 × 104 M−1s−1 for cystamine). The time course of disulfide loss and product formation (determined by LC-MS) support a role for 1O 2 , with mono- and di-oxygenated products detected. Elevated levels of these latter species were generated in D 2 O- compared to H 2 O buffers, which is consistent with solvent effects on the 1O 2 lifetime. These data are interpreted in terms of the intermediacy of a zwitterion [–S+(OO−)–S–], which either isomerizes to a thiosulfonate [–S(O) 2 –S–] or reacts with another parent molecule to give two thiosulfinates [–S(O)–S-]. The variation in quenching rates and product formation are ascribed to zwitterion stabilization by neighboring, or remote, lone pairs of electrons. These data suggest that some disulfides, including some present within or attached to proteins (e.g., α-lipoic acid), may be selectively modified, and undergo subsequent cleavage, with adverse effects on protein structure and function. [Display omitted] • Kinetics of disulfide-mediated 1O 2 removal monitored using time-resolved phosphorescence. • Rate constants for 1O 2 removal show a marked variation with structure (103 -107 M−1 s−1). • 5-membered ring disulfides (lipoic acid, lipoamide) react more rapid than linear disulfides. • LC-MS analyses show formation of mono- (thiosulfinate) and di-oxygenated (thiosulfonate) products. • Protein disulfides may show similar variable reactivity and selective oxidation. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of 2,4,6-triaryl pyridines is disclosed. Singlet molecular oxygen generated from trans-5-hydroperoxy-3,5-dimethyl-1,2-dioxolane-3-yl ethaneperoxate has been explored as an effective oxidant for oxidative cleavage of C-N bond in the synthesis of 2,4,6-trisubstituted pyridines from benzylamines and aryl methyl ketones. The convenient preparation of the reagent, simple reaction procedures, avoidance of transition metal catalysts, good-to-excellent yields, short reaction times, and synthesis of asymmetric pyridine derivate are some of the advantages of this protocol. Thus, this protocol may serve as a potential synthetic method for the synthesis of 2,4,6-trisubstituted pyridines. Singlet molecular oxygen generated from trans-5-hydroperoxy-3,5-dimethyl-1,2-dioxolane-3-yl ethaneperoxate/n-Bu4NF has been explored as an effective oxidant for oxidative cleavage of C-N bond in the synthesis of 2,4,6-trisubstituted pyridines. The avoidance of transition metal catalysts, good-to-excellent yields, and synthesis of symmetric and asymmetric pyridine derivates are some of the advantages of this protocol. [ABSTRACT FROM AUTHOR]

A synthetic approach to two regioisomeric π‐electron extended [1,4]thiaborins annulated with two benzothiophene units has been developed. The central thiaborin rings of the boracycles obtained exhibit different electronic properties; this is reflected in their different aromatic characters, boron Lewis acidity and UV‐vis spectroscopic behavior. Thiaborins were converted to boron dipyrromethene (BODIPY) complexes. Their emission spectra exhibit two distinct bands resulting from 1LE and 1CT transitions. Strong near‐infrared phosphorescence in Zeonex thin films at 77 K indicates efficient intersystem crossing and the formation of triplet states. Separation of HOMO and LUMO orbitals between boracyclic and BODIPY moieties facilitates electron transfer to a 1CT state followed by a transition to the 3LE triplet state located on the ligand. These unique properties of spiro thiaborin‐BODIPY complexes were explored for their application as singlet‐oxygen photosensitizers. They show excellent photocatalytic performance with singlet oxygen quantum yields reaching 77 % and full conversion of the model organic substrate achieved after 1.5 h with only 0.05 % mol catalyst load. [ABSTRACT FROM AUTHOR]

One key challenge in the development of viable organic photovoltaic devices is to design component molecules that do not degrade during combined exposure to oxygen and light. Such molecules should thus remain comparatively unreactive towards singlet molecular oxygen and not act as photosensitizers for the generation of this undesirable species. Here, novel redox‐active chromophores that combine these two properties are presented. By functionalizing indenofluorene‐extended tetrathiafulvalenes (IF‐TTFs) with cyano groups at the indenofluorene core using Pd‐catalyzed cyanation reactions, we find that the reactivity of the exocyclic fulvene carbon‐carbon double bonds towards singlet oxygen is considerably reduced. The new cyano‐functionalized IF‐TTFs were tested in non‐fullerene acceptor based organic photovoltaic proof‐of‐principle devices, revealing enhanced device stability. [ABSTRACT FROM AUTHOR]

The efficiency of photodynamic therapy is often limited by the scarcity of oxygen at the target site. To address this problem, this work proposes the development of a new nanosystem for antimicrobial photodynamic therapy applications (aPDT) where the natural-origin photosensitizer curcumin (CUR) is immersed in an oxygen-rich environment. Inspired by the perfluorocarbon-based photosensitizer/O2 nanocarriers reported in the literature, we developed a new type of silica nanocapsule containing curcumin dissolved in three hydrophobic ionic liquids (ILs) with high oxygen dissolving capacities. The nanocapsules (CUR-IL@ncSi), prepared by an original oil-in-water microemulsion/sol-gel method, had a high IL content and exhibited clear capacities to dissolve and release significant amounts of oxygen, as demonstrated by deoxygenation/oxygenation studies. The ability of CUR-IL solutions and of CUR-IL@ncSi to generate singlet oxygen (1O2) upon irradiation was confirmed by the detection of 1O2 phosphorescence at 1275 nm. Furthermore, the enhanced capacities of oxygenated CUR-IL@ncSi suspensions to generate 1O2 upon irradiation with blue light were confirmed by an indirect spectrophotometric method. Finally, preliminary microbiological tests using CUR-IL@ncSi incorporated into gelatin films showed the occurrence of antimicrobial effects due to photodynamic inactivation, with their relative efficiencies depending on the specific IL in which curcumin was dissolved. Considering these results, CUR-IL@ncSi has the potential to be used in the future to develop biomedical products with enhanced oxygenation and aPDT capacities. [ABSTRACT FROM AUTHOR]

In this study, Co-modified alkalinized g-C3N4 (named Co-CNK-OH) was prepared for the Fenton-like photocatalytic degradation of tetracycline (TC) via a simple yet effective calcination–impregnation method. In all samples of CNK-OH with different Co2+ loadings, Co-CNK-OH catalyst with the optimal content (9%) exhibited the highest catalytic activity, with 87.1% tetracycline removal and 50% removal efficiency of the total organic carbon (TOC). Mechanism studies revealed that the 9%Co-CNK-OH catalyst had the lower electrical resistance after alkalization treatment and Co2+ modification, leading to a significantly accelerated interfacial charge transfer to the electron acceptor as well as effectively separating electrons and holes. The intermediates generated during the TC degradation in the photo-Fenton process were detected by HPLC-MS, which proved that the holes, superoxide radicals, and singlet oxygen are the key reactive species in the Fenton-like photocatalysis. This study provides a new option for the treatment of TC in wastewater. [ABSTRACT FROM AUTHOR]

The excited triplet state of a molecule (T1) is one of the principal intermediate products in various photochemical processes due to its high reactivity and relatively long lifetime. The T1 quantum yield ( φ T ) is one of the most important characteristics in the study of photochemical reactions. It is of special interest to determine the φ T of various photoactive compounds (photosensitizer, PS) used in photodynamic therapy (PDT). PDT is an effective medical technique for the treatment of serious diseases, such as cancer and bacterial, fungal and viral infections. This technique is based on the introduction of a PS to a patient's organism and its further excitation by visible light, producing reactive oxygen species (ROS) via electron or energy transfer from the PS T1 state to the biological substrate or molecular oxygen. Therefore, information on the φ T value is fundamental in the search for new and effective PSs. There are various experimental methods to determine φ T values; however, these methods demonstrate a high discrepancy between φ T values. This stimulates the analysis of various factors that can affect the determined φ T . In this study, we analyze the effect of the intensity profile of the exciting laser pulse on the calculation of the φ T value obtained by the Laser Flash Photolysis technique. The φT values were determined by analyzing the variation of a sample transient absorption in the function of the exciting laser pulse intensity, in combination with the spectral and kinetic PS characteristics obtained in nonlinear optical experiments by solving the rate equations of a five-level-energy diagram. Well-studied PSs: meso-tetra(4-sulfonatophenyl) (TPPS4) porphyrins, its zinc complex (ZnTPPS4) and the zinc complex of meso-tetrakis(N-methylpyridinium-4-yl) (ZnTMPyP) were chosen as test compounds to evaluate the proposed model. The φ T values were determined through a comparison with the φ T , T M P y P = 0.82 of meso-tetrakis(N-methylpyridinium-4-yl) (TMPyP), used as a standard. The obtained results ( φ T , T P P S 4 = 0.75 ± 0.02 , φ T , Z n T M P y P = 0.90 ± 0.03) , and φ T , Z n T P P S 4 = 0.89 ± 0.03 ) are highly compatible with the medium φ T values obtained using the known methods. [ABSTRACT FROM AUTHOR]

Phenazinone derivatives PZ1–3 where a carbonyl group is incorporated into the chromophore are designed and developed as halogen-atom-free-heteroanthracene-based photosensitizers possessing the ability to generate singlet oxygen (1O2). Compared to the phenazine-2,3-diol (PZ) without a carbonyl group, the molar absorption coefficients of PZ1–3 at around 480 nm increased by a factor of five to six. Furthermore, the values of fluorescence quantum yields (Φfl) of PZ1–3 were significantly low (0.03 for PZ1, 0.04 for PZ2, and 0.05 for PZ3). To evaluate the 1O2 generation ability of PZ1–3, the 1O2 quantum yields (ΦΔ) of PZ1–3 were estimated and it was demonstrated that PZ1 exhibited a higher ΦΔ value than rose bengal (RB) known as a reference photosensitizer to generate 1O2 (0.86 for PZ1, 0.54 for PZ2, 0.069 for PZ3, and 0.68 for RB). Moreover, the rate constants (kr, knr, kISC, and kIC) of PZ1–3 indicated that the reason for the low ΦΔ of PZ2 and PZ3 comes from the vibrational relaxation caused by a flexible methoxymethoxy and 4-chlorobenzoate group, respectively. Density functional theory (DFT), time-dependent DFT (TD-DFT), and natural transition orbital (NTO) calculations suggested that for PZ1–3, the intersystem crossing (ISC) processes from the lowest excited singlet state (S1) to the third triplet state (T3) are thermodynamically feasible and facilitated based on El-Sayed's rule. Consequently, we propose that the phenazinone skeleton is one of the promising halogen-atom-free-heteroanthracene-based chromophore photosensitizers. [ABSTRACT FROM AUTHOR]

Photodestruction of 2-(pyrazin-2′-yl)-1H-indole and 2,5-di(1H-indol-2′-yl)pyrazine involves singlet oxygen generation and its rapid insertion into the indole ring with the formation of benzoxazinone derivatives: 2-(pyrazin-2-yl)-4H-3,1-benzoxazin-4-one and 2-[5-(1H-indol-2-yl)pyrazin-2-yl]-4H-3,1-benzoxazin-4-one. The quantum yield of this reaction strongly depends on the environment. It is definitely smaller in protic methanol than in aprotic acetonitrile or n-hexane. The observed effect of photostabilization is explained by formation of hydrogen bonded complexes between the chromophore and alcohol, which results in lower triplet formation efficiency and, in consequence, decrease of singlet oxygen formation quantum yield. [ABSTRACT FROM AUTHOR]

Due to the highly selective nature of singlet oxygen as an oxidant, it has received considerable interest in various areas of (organic) chemistry. Two green light activated hydrazone-based boron difluoride triplet photosensitizers possessing high quantum yields for 1O2 formation are reported. These photostable complexes are promising in applications in synthesis and catalysis. [ABSTRACT FROM AUTHOR]

It is known that C40 carotenoids with a short chain of conjugated double bonds (CDB) (5 and 7, respectively) are universal precursors in the biosynthesis of colored carotenoids in plant cells. Previously, using mainly stationary measurements of photosensitized phosphorescence of singlet oxygen (1O2), we discovered that phytofluene efficiently generates 1O2 in aerated solution and therefore, can serve as a source of the UV photodynamic stress in living cells [Ashikhmin et al., Biochemistry (Moscow), 2020, 85, 773]. In the present paper, by using novel pulsed light emitting diodes (LEDs), aerated hexafluorobenzene as a solvent and time-resolved measurements of 1O2 phosphorescence we confirmed that phytofluene efficiently photosensitizes 1O2 formation. The quantum yield of this process according to the novel experiments is about 0.4. An ability to generate 1O2 was also found in aerated solutions of ζ-carotene although the quantum yield of this process is 30-fold lower that in phytofluene solutions. Both carotenoids were found to quench 1O2 in the dark with the quenching rate constants equal to (3.6 ± 0.9)×107 and (2.1 ± 0.2)×108 M–1s–1, respectively. To our knowledge, the rate constant of 1O2 quenching by ζ-carotene has been reported in the present paper for the first time. It follows from the data obtained that the rate constants of 1O2 quenching by both carotenoids are much (by 2-3 orders of magnitude) smaller than the rate constant of the diffusion-limited biomolecular reactions. Hence, both carotenoids are weak protectors against 1O2 oxidative activity. It is more likely that they are potential promoters of photodynamic stress in living cells. [ABSTRACT FROM AUTHOR]

Presented herein are two fully characterized gold tetrathiocyanocorroles representing a potentially significant new class of NIR-emissive 5d-metallocorroles. The four SCN groups on the bipyrrole unit of the corrole exert a powerful electron-withdrawing effect, upshifting both the oxidation and reduction potentials by roughly half a volt relative to their unsubstituted counterparts. That said, the upshift of the LUMO is somewhat higher than that of the HOMO so these complexes also exhibit a smaller HOMO–LUMO gap, as evinced in both electrochemical measurements and Q band energies (∼595 nm relative to ∼571 nm for their SCN-free counterparts). The new compounds exhibit NIR phosphorescence under ambient conditions with emission maxima around 900 nm (compared with 790 nm for simple Au triarylcorroles), phosphorescence quantum yields around 0.3%, phosphorescence lifetimes around 10 μs, and singlet oxygen sensitization with a quantum yield of around 50 ± 5% in solution, together signifying wide-ranging potential applications as triplet photosensitizers in oxygen sensing and photodynamic therapy. [ABSTRACT FROM AUTHOR]

Visible light-sensitized oxidation of micropollutants (MPs) in the presence of meso-tetrakis(4-sulfonatophenyl)porphyrin photosensitizers was studied. In order to explore the role of type I (ROS generation) or type II (singlet oxygen) photooxidation, radical scavengers were used to obtain insight into the mechanism of photodegradation. It was revealed that singlet oxygen is the main ROS taking part in TPPS4- sensitized photooxidation of micropollutants. The interaction of MPs with 1O2 in deuterium oxide (D2O) was investigated by measuring the phosphorescence lifetime of 1O2. The rate constant (kq) for the total (physical and chemical) quenching of 1O2 by MPs was determined in a D2O buffer (pD 7, 9 and 10.8). The rate constants of singlet oxygen quenching and reaction with MPs were determined, and the rate constant of excited TPPS4 quenching by MPs was also estimated. [ABSTRACT FROM AUTHOR]

Long triplet lifetimes of excited photosensitizers are essential for efficient energy transfer reactions in water, given that the concentrations of dissolved oxygen and suitable acceptors in aqueous media are typically much lower than in organic solvents. Herein, we report the design, synthesis and photochemical characterization of two structurally related water-soluble ruthenium complex-based dyads decorated with a covalently attached pyrene chromophore. The triplet energy of the latter is slightly below that of the metal complex enabling a so-called triplet reservoir and excited-state lifetime extensions of up to two orders of magnitude. The diimine co-ligands, which can be modified easily, have a major impact on both the ultrafast intramolecular energy transfer (iEnT) kinetics upon excitation with visible light and the lifetime of the resulting long-lived pyrene triplet. The phenanthroline-containing dyad shows fast triplet pyrene formation (25 ps) and an exceptionally long triplet lifetime beyond 50 microseconds in neat water. The iEnT process via the Dexter mechanism is slower by a factor of two when bipyridine co-ligands are employed, which is rationalized by a poor orbital overlap. Both dyads are very efficient sensitizers for the formation of singlet oxygen in air-saturated water as well as for the bimolecular generation of anthracene triplets that are key intermediates in upconversion mechanisms. This is demonstrated by the 5-hydroxymethylfurfural oxidation, which yields completely different main products depending on the pH value of the aqueous solution, as an initial application-related experiment and by time-resolved spectroscopy. Our findings are important in the greater contexts of photocatalysis and energy conversion in the "green" solvent water. [ABSTRACT FROM AUTHOR]

The endoperoxides of β-carotene (βCar-EPOs) are regarded as main products of the chemical deactivation of 1O2 by β-carotene, one of the most important antioxidants, following a concerted singlet-singlet reaction. Here we challenge this view by showing that βCar-EPOs are formed in the absence of 1O2 in a non-concerted triplet-triplet reaction: 3O2 + 3β-carotene → βCar-EPOs, in which 3β-carotene manifests a strong biradical character. Thus, the reactivity of β-carotene towards oxygen is governed by its excited triplet state. βCar-EPOs, while being stable in the dark, are photochemically labile, and are a rare example of nonaromatic endoperoxides that release 1O2, again not in a concerted reaction. Their light-induced breakdown triggers an avalanche of free radicals, which accounts for the pro-oxidant activity of β-carotene and the puzzling swap from its anti- to pro-oxidant features. Furthermore, we show that βCar-EPOs, and carotenoids in general, weakly sensitize 1O2. These findings underlie the key role of the triplet state in determining the chemical and photophysical features of β-carotene. They shake up the prevailing models of carotenoid photophysics, the anti-oxidant functioning of β-carotene, and the role of 1O2 in chemical signaling in biological photosynthetic systems. βCar-EPOs and their degradation products are not markers of 1O2 and oxidative stress but of the overproduction of extremely hazardous chlorophyll triplets in photosystems. Hence, the chemical signaling of overexcitation of the photosynthetic apparatus is based on a 3chlorophyll-3β-carotene relay, rather than on extremely short-lived 1O2. The endoperoxides of β-carotene play a key role in signaling of photooxidative stress in plant cells and are regarded as the products of chemical deactivation of singlet oxygen. The authors show that these compounds are instead formed in a reaction between oxygen and β-carotene in their triplet states, revealing the importance of the triplet states in the photoprotection of photosynthetic apparatus. [ABSTRACT FROM AUTHOR]

[Display omitted] • The composites showed slow Cu2+ release, and rough appearance of the material. • The ZnO/Cu 2 O showed highly efficient antibacterial performance. • The increase in electron and hole production of composite materials enhances their antibacterial properties. Composite antibacterial materials were prepared by loading ZnO with good stability and biocompatibility on Cu 2 O. Cu2+ was released slowly due to the loading of ZnO, so the ZnO-Cu 2 O composites achieved lasting antibacterial effect. The basic form of the resulting ZnO/Cu 2 O composites, chemical composition, and crystal structure analyses were carried out by scanning electron microscopy (SEM), electron diffraction spectroscopy, Brunauer–Emmett–Teller method, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and X-ray phosphorescence. The optical properties of ZnO/Cu 2 O composites were determined by UV–vis spectroscopy and photoluminescence spectroscopy. E. coli and S. aureus were used to detect the antibacterial properties of the ZnO/Cu 2 O composites. The antibacterial mechanism of ZnO/Cu 2 O composites was investigated through ion dissolution, reactive oxygen species (ROS), and mechanical damage experiments. The results show that the increase in specific surface area, slow release of Cu2+ and increase in ROS lead to better antibacterial activity of ZnO/Cu 2 O composites. The antibacterial mechanism of these ZnO/Cu 2 O composites involves ion release, active oxygen and mechanical damage. The internal damage of bacteria was further analyzed by lipid peroxidation, protein leakage, respiratory chain dehydrogenase activity and bacteria in vitro fluid ion to thoroughly understand the inactivation mechanism of bacteria by the composite antibacterial material. [ABSTRACT FROM AUTHOR]

Application of NIR (near-infrared) emitting transition metal complexes in biomedicine is a rapidly developing area of research. Emission of this class of compounds in the "optical transparency windows" of biological tissues and the intrinsic sensitivity of their phosphorescence to oxygen resulted in the preparation of several commercial oxygen sensors capable of deep (up to whole-body) and quantitative mapping of oxygen gradients suitable for in vivo experimental studies. In addition to this achievement, the last decade has also witnessed the increased growth of successful alternative applications of NIR phosphors that include (i) site-specific in vitro and in vivo visualization of sophisticated biological models ranging from 3D cell cultures to intact animals; (ii) sensing of various biologically relevant analytes, such as pH, reactive oxygen and nitrogen species, RedOx agents, etc.; (iii) and several therapeutic applications such as photodynamic (PDT), photothermal (PTT), and photoactivated cancer (PACT) therapies as well as their combinations with other therapeutic and imaging modalities to yield new variants of combined therapies and theranostics. Nevertheless, emerging applications of these compounds in experimental biomedicine and their implementation as therapeutic agents practically applicable in PDT, PTT, and PACT face challenges related to a critically important improvement of their photophysical and physico-chemical characteristics. This review outlines the current state of the art and achievements of the last decade and stresses the most promising trends, major development prospects, and challenges in the design of NIR phosphors suitable for biomedical applications. [ABSTRACT FROM AUTHOR]

Amino-acyl-quinoxalinone yellow dyes are cyclised analogues of the yellow azomethine dyes developed for, and still used in, silver halide colour photography. Unlike image azomethine dyes, which are rapidly deactivated in their excited states by torsion about the azomethine bond, amino-acyl-quinoxalinone dyes have an interesting photophysics because torsion is not possible due to their cyclised structure. We report results from studies on singlet and triplet state properties, and singlet oxygen yields, of the yellow dye, 7-diethylamino-3-(2,2-dimethyl-propionyl)-5-methyl-1-phenyl-1H-quinoxalin-2-one, in polar and nonpolar solvents. The dye photophysics is characterised by a weak fluorescence, with a solvent dependent emission yield (ΦF ≈ 0.002–0.004), and short singlet state lifetime (τexpt ≈ 20–50 ps), both increasing by a factor of ≈2 in going from polar acetonitrile to non-polar dioxane as solvent. DFT ZINDO calculations show a transition involving significant electron transfer from the diethyl-amino group into the carbonyl region of the molecule. In solution, in the presence of oxygen, the triplet state decays almost exclusively by oxygen quenching, and singlet oxygen is produced in high yield (Φ∆ ≈ 0.5–0.55). The triplet state absorbs across the 450–750 nm region with maxima around 480 and 650 nm, and moderate molar absorption coefficients (ca. 6000–8000 M−1 cm−1). In a glass at 77 K, triplet decay gives a red phosphorescence, with λmax ≈ 640–650 nm, and a ≈ 0.25 s lifetime. If singlet oxygen yields are a good indication of triplet yields, then internal conversion and intersystem crossing occur with roughly equal efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Octahedral halide M 6 clusters possess a set of practically oriented properties. • The main drawback of the clusters is their severe hydrolytic instability. • Incorporation into matrix efficiently stabilizes clusters in aqueous media. • Clusters can interact with a matrix through various bond types. • Bond types realized in materials are covalent, ionic, weak, or their combination. The history of the chemistry of halide octahedral cluster complexes began long ago in the 19th century, but to this day these compounds have not lost their topicality or even become more relevant. The unique combination of useful properties of cluster compounds, including bright red phosphorescence, photosensibilization of the singlet oxygen generation process, and high radiopacity, forecasts the possibility of using such complexes in practical oriented fields. To overcome the main issue of these compounds – low hydrolytic stability, which hinders their application in real conditions, researchers are actively applying the approach of creating functional cluster-containing materials by incorporating active component into the matrices of different nature (organic, inorganic, hybrid). This approach has demonstrated significant efficiency, resulting in the accumulation of a large amount of data, and according to the analysis of literature data, this area is currently under active development. Complexes can be bound in a variety of ways, determined by the presence or absence of functional groups in the matrix/cluster, as well as by chemical transformations that occur with the cluster during material preparation. The types of binding modes include strong (ionic and covalent) and weak (hydrogen electrostatic, supramolecular, hydrophobic, etc.) interactions and combinations thereof. In addition, matrix properties (oxygen permeability, solubility/insolubility, robustness, optical transparency, luminescent properties) can significantly influence or even enhance the properties of the resulting material. The efficient stabilization of the complexes, as well as the rich variety of possible matrices, provides a wide range of different applications for these materials, only some of which have been demonstrated to date. This review aims to classify the existing synthetic approaches for the preparation of functional cluster-containing materials within the nature of the bonding of cluster units to the matrix. [ABSTRACT FROM AUTHOR]

Modeling reactions involving singlet molecular oxygen (O2 [1Δg]) is challenging because the degeneracy of the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO and LUMO) orbitals of oxygen causes a significant multireference character. Within the limit that singlet‐singlet near‐degeneracy disappears in the transition state, it would be possible to bypass singlet oxygen's multireference character by simply adding the experimentally determined singlet/triplet splitting (22.5 kcal/mol) to the energy of the triplet ground state of molecular oxygen. This method is tested by calculating rate constants for the reactions of singlet molecular oxygen with furan, 2‐methylfuran, 2,5‐dimethylfuran, pyrrole, 2‐methylpyrrole, 2,5‐dimethylpyrrole, and cyclopentadiene using transition state theory. We find that the reaction rate coefficients are within a factor of 15 of experimentally determined rate constants, indicating an error in the barrier energy of roughly 3 kcal/mol. Furthermore, we find that energy refinement at the CCSD(T)‐F12 level of theory is crucial to achieving accurate results. We conclude that, based on a comparison with an experiment, this approximation is valid to some degree and can be used for other systems involving the 1,4‐cyclo‐addition of singlet oxygen. [ABSTRACT FROM AUTHOR]

A series of four oligothiophenes end‐capped with −Pt(PBu3)2Cl moieties on both ends of the oligomers was synthesized, and their excited state properties were investigated. The observation of low fluorescence quantum yield (<2 %) for the oligomers indicates the strong effect of platinum on the intersystem crossing (ISC) efficiency. No phosphorescence was detected for any of the oligomers; however, strong triplet‐triplet absorption was observed by nanosecond transient spectroscopy for oligomers with more than one thiophene unit. The oligomers displayed short triplet lifetimes (∼1–2 μs) compared to the unmetallated oligomers, due to large spin‐orbit coupling induced by the platinum atom. The lower limits of the ISC yields were indirectly determined by measuring the singlet oxygen quantum yields. Femtosecond–picosecond transient absorption studies revealed that the ISC rate ranges from 1012–1010 s−1, decreasing with increasing oligomer length. Electrochemical studies showed that the oligomers exhibit relatively low oxidation potentials (ca. 0.1 V vs. Fc/Fc+). Quenching of the oligomers' triplet state absorption, simultaneously with the rise of their corresponding cationic radical absorption band in nanosecond transient spectra in the presence of methyl viologen, as an electron acceptor, established that the electron transfer occurs from their triplet state. [ABSTRACT FROM AUTHOR]

Singlet oxygen represents a form of reactive oxygen species (ROS), produced by electronic excitation of molecular triplet oxygen. In general, highly reactive oxygen‐bearing molecules remain the backbone of diverse ground‐breaking technologies, driving the waves of scientific development in environmental, biotechnology, materials, medical and defence sciences. Singlet oxygen has a relatively high energy of about 94 kJ/mol compared to the ground state molecular O2 and therefore initiates low‐temperature oxidation of electron‐rich hydrocarbons. Such reactivity of singlet oxygen has inspired a wide array of emerging applications in chemical, biochemical and combustion phenomena. This paper reviews the intrinsic properties of singlet oxygen, emphasising the physical aspects of its natural occurrences, production techniques, as well as chemical reactivity with organic fuels and contaminants. The review assembles critical scientific studies on the implications of singlet oxygen in initiating chemical reactions, identifying, and quantitating the consequential effects on combustion, fire safety, as well as on the low‐temperature treatment of organic wastes and contaminants. Moreover, the content of this review appraises computational efforts, such as DFT quantum mechanical modelling, in developing mechanistic (i. e., both thermodynamic and kinetic) insights into the reaction of singlet oxygen with hydrocarbons. [ABSTRACT FROM AUTHOR]

A new type of luminescence switching behavior based on phosphorescence enhancement from a series of metal‐free organic phosphors doped polymers by UV‐irradiation is investigated. This phenomenon is observed only from pairs of organic phosphors and polymer matrices having a combination of appropriate triplet exciton lifetime and oxygen permeability. Systematic investigation reveals that the luminescence switching behavior of organic phosphors embedded in a specific polymeric matrix stems from the conversion of triplet oxygens to singlet oxygens by UV‐irradiation, leading to the unique phosphorescence enhancement of organic phosphors. Visualization of latent information by UV‐irradiation is demonstrated toward novel secure information communication applications. [ABSTRACT FROM AUTHOR]

Four ball-type phthalocyanines (H22c, MgPc, CoPc, and ZnPc) containing 4-tert-butylcatechol substituents at alpha-positions were synthesized from 3,3'-(4-tert-butyl-1,2-phenylene)bis(oxy)diphthalonitrile. The structures were elucidated by elemental analysis and ultraviolet-visible, Fourier-transform infrared, proton nuclear magnetic resonance, and Maldi-Tof mass spectroscopies. The photophysicochemical properties of H2Pc, MgPc, and ZnPc were investigated in dimethylsulphoxide. The fluorescence quantum yields (FF), triplet state quantum yields (ΦT), and singlet oxygen quantum yields (ΦΔ) with respect to H2Pc, MgPc and ZnPc were experimentally obtained. Furthermore, the degradation quantum yield (Φd) was evaluated for all complexes. Finally, the magnetic circular dichroism spectra of the four Pcs were obtained. Among these ball-type phthalocyanines, MgPc had the highest triplet lifetime and ZnPc had the highest singlet oxygen quantum yield. Moreover, the in vitro antiproliferative effect of ball-type phthalocyanines (H2Pc, MgPc, CoPc, and ZnPc) was evaluated on MCF-7 cell line originated from luminal A breast cancer and MDA-MB-231 cell line originated from triple negative breast cancer. For this purpose, cell viability MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used. For all compounds, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8, 25.6, 51.2, 102.4 µM concentrations were applied to both cell lines. There was a significant decrease in cell viability for MCF-7 and MDA-MB-231 cells (p<0.05). [ABSTRACT FROM AUTHOR]

In recent years there has been a growing interest in merging different types of catalysis to create new multistep catalytic processes. However, the majority of reported dual catalysis strategies use a mixture of individual catalysts, with limited reports of dual catalysis reactions where the different catalysts are combined in a single compound. This work reports the synthesis of a tethered palladium-BODIPY dual catalyst to enable increased synergistic interactions between the catalytic centres. Detailed analysis, including single crystal X-ray crystallography, absorption, fluorescence, and phosphorescence measurements, and kinetic analyses to determine singlet oxygen quantum yields, confirm that chemical tethering results in a significant increase in the photocatalytic potential of the palladium-BODIPY dual catalyst, relative to the parent BODIPY chromophore. Interestingly, the palladium-BODIPY complex also exhibited rare long-lived room temperature phosphorescence. Catalytic applications of the palladium-BODIPY dual catalyst indicate that chemical tethering increases the reactivity of the catalytic centres for both photocatalytic oxidation of thioanisole and palladium catalysed Suzuki–Miyaura cross coupling, highlighting that enhancements in both photo and thermally activated catalysis can be achieved on chemical tethering. In addition, the dual catalytic potential of the palladium-BODIPY catalyst was demonstrated using a representative sequential photocatalytic oxidation–cross coupling reaction. A tethered dual catalyst has been synthesised and fully characterised, where a BODIPY photocatalyst and a palladium catalyst were combined in one complex. The catalytic activity of the catalyst was investigated through both photocatalytic and transition metal catalysed reactions, demonstrating that chemical tethering enhances catalysis. The dual catalytic ability of the complex was demonstrated through stimuli controlled (heat or light) sequential reactivity. [ABSTRACT FROM AUTHOR]

In this study, a strategy using Partial Least Squares (PLS) as a chemometric tool to establish the robustness of the photosensitized degradation process of Bisphenol A in simulated effluents was assessed. In the first stage of the research, the validation of the methodology that allows the quantification of Bisphenol A (BPA) mixed with the photosensitizer Eosin Y (EOS) in aqueous solution was carried out. Through the use of spectrophotometry as monitoring technique, it was possible to establish the optimal number of factors and the wavelength range, and to determine that was possible to ensure the quantification of BPA by means of PLS, by demonstrating complex formation between BPA and EOS. The RMSE results were 0.004237 at 284 nm and 0.009167 at 524 nm, demonstrating good robustness in the analysis. Next, preliminary tests were carried out on the effect of direct light using a mercury lamp as a source of irradiation. In the case of BPA, it was determined that 100% degradation is achieved at 100 minutes. [ABSTRACT FROM AUTHOR]

The investigation on the catalytic properties of porous organic cages is still in an initial stage. Herein, the reaction of cyclohexanediamine with 5,15-di[3',5'-diformyl(1,1'-biphenyl)]porphyrin affords a porphyrin tubular organic cage, PTC-1(2H). Transient absorption spectroscopy in solution reveals much prolonged triplet lifetime of PTC-1(2H) relative to monomer reference, illustrating the unique photophysical behavior of cagelike photosensitizer. The long triplet lifetime ensures high-efficiency singlet oxygen evolution according to homogeneous photo-bleach experiment, electron spin-resonance spectroscopy, and aerobic photo-oxidation of benzylamine. Furthermore, microporous supramolecular framework of PTC-1(2H) is able to promote the heterogeneous photo-oxidation of various primary amines with conversion efficiency above 99% under visible light irradiation. These results indicate the great application potentials of porous organic cages in heterogeneous phase. The investigation on the catalytic properties of porous organic cages is still in an initial stage. Herein, the heterogeneous photocatalytic superiority of microporous porphyrin organic cage has been clearly elucidated due to unique cage-induced long triplet lifetime and porous structure. [ABSTRACT FROM AUTHOR]

Three new 2-component unsubstituted (4P), diiodo- (5P), and dibromo- (6P) distyryl-BODIPY-bridged cyclotriphosphazene dimers were designed and synthesized. The newly synthesized BODIPY-cyclotriphosphazene systems were characterized by ¹H, 13C, and 31P NMR spectroscopy. The photophysical properties of the distryl-BODIPYs (4-6) and BODIPY-cyclotriphosphazene dyads (4P-6P) were studied by UV-Vis absorption and fluorescence emission spectroscopy. In these derivatives, the bino-type cyclotriphosphazene derivative bearing unsubstituted BODIPY unit 4 P exhibited high fluorescence and no singlet oxygen generation due to the lack of spin converter. The attachment of heavy atoms (iodine and bromine) enabled the production of singlet oxygen. The bino-type BODIPY-cyclotriphosphazenes (5P and 6P) were also used as triplet photosensitizers in the photooxidation of 1,3-diphenylisobenzofuran to endoperoxide via generation of the singlet oxygen in dichloromethane. The singlet oxygen production of these compounds was also investigated via a direct method and produced a singlet oxygen phosphorescence peak at 1270 nm. [ABSTRACT FROM AUTHOR]

In photocatalytic system, singlet oxygen can be generated based on the excitonic energy transfer process. Here, the 2D layered hallyosite (Hal) as a support hydroxyl group's substrate to anchor molybdenum trioxide (MoO 3-x) with oxygen vacancies (Hal/MoO 3-x) was prepared. Electron spin resonance and quenching experiments showed that the combination of Hal and MoO 3-x enhances the generation of singlet oxygen (1O 2) and inhibits the production of other reactive oxygen species. Furthermore, photocatalytic molecular oxygen activation experiments were carried out to evaluation of 1O 2 generation. Phosphorescence spectroscopy revealed improved triplet exciton production in the composite. The Hal/MoO 3-x shows great degradation response in TC removal. The value for the rate constant (k) of the composite was 0.0209 min−1 under light irradiation, which is about 5.64 and 3.02 times larger than that of Hal, MoO 3 and MoO 3-x , respectively. The results revealed that Hal/MoO 3-x had the best antibacterial performance. The L. monocytogenes , and N. gonorrhoeae were killed by the destruction of the cell membranes due to the generation of reactive oxygen species and thermal effect. In addition, a colorimetric sensor via the Hal/MoO 3-x and peroxidase system was performed for selectivity and sensitivity detection of simazine with 2.45 nM as a detection limit. [ABSTRACT FROM AUTHOR]

• CDs derived from chlorine 6 and polyethylene imine were prepared. • CDs could emit NIR phosphorescence with long lifetime over 2 h. • CDs with large tissue penetration (10 mm) and high SNR (98.4). • CDs can be used for deep-tissue and long-term in vivo persistent luminescent imaging. • CDs can produce reactive oxygen species to achieve promoted photodynamic therapy. Imaging-guided photodynamic therapy (PDT) has the features of precise location and non-invasiveness. However, most of the photosensitizers (PSs) for PDT are poor fluorescent emitters, and the inadequate fluorescence is usually interfered by tissue auto-fluorescence. The afterglow phosphorescence could ideally address the issues of fluorescence imaging. Therefore, it is of double benefit to design phosphorescent CDs for enhanced near-infrared (NIR) phototheranostics. Hereon, we synthesized CDs with excellent biosafety, outstanding stability, good water dispersibility and effective photodynamic activity. CDs could emit NIR luminescence with long lifetime over 2 h, which afforded large tissue penetration (10 mm) and high SNR (98.4) for deep-tissue and long-term in vivo persistent luminescent imaging. Moreover, abundant reactive oxygen species generated by CDs enabled NIR afterglow imaging-guided PDT to effectively inhibit tumor growth. This work demonstrates the enormous potential of CDs as multifunctional nanoplatforms for biomedical application. [ABSTRACT FROM AUTHOR]

Aliphatic triplet carbonyls can be treated as short-lived radicals, since both species share similar reactions such as hydrogen atom abstraction, cyclization, addition, and isomerization. Importantly, enzyme-generated triplet carbonyls excite triplet molecular oxygen to the highly reactive, electrophilic singlet state by resonance energy transfer, which can react with proteins, lipids, and DNA. Carbonyl triplets, singlet oxygen, and radicals are endowed with the potential to trigger both normal and pathological responses. In this paper, we present a short review of easy, fast, and inexpensive preliminary tests for the detection of transient triplet carbonyls in chemical and biological systems. This paper covers direct and indirect methods to look for triplet carbonyls based on their spectral distribution of chemiluminescence, photoproduct analysis, quenching of light emission by conjugated dienes, and enhancement of light emission by the sensitizer 9,10-dibromoanthracence-2-sulfonate ion (DBAS). [Display omitted] • Triplet carbonyls are reportedly produced by dioxetane and peroxyl radical intermediates of biological processes. • Hydrogen abstraction, addition, and cleavage reactions are shared by triplet and radical species. • Direct and DBAS enhanced chemiluminescence can give clues for searching triplets in biological samples. • Quenching of carbonyl triplets by conjugated dienes like sorbates is diffusion-controlled. • Implication of triplet carbonyls in illness is still neglected in biomedicine. [ABSTRACT FROM AUTHOR]

We report a rational and scalable synthetic approach to prepare Fe-decorated carbon nitride materials assisted by carbonized polyamine (C-Fe@PDA-CN). The material exhibited extremely high activity and stability for the degradation of 2-mercaptobenzothiazole (MBT) and other organic pollutants (phenol, BPA, MB, and RhB) under visible light irradiation. Furthermore, escape from CN to C-Fe@PDA provides an electron transfer channel to facilitate carrier separation and accelerate the generation of active species, as confirmed by photoluminescence, photoelectrochemical, and electron paramagnetic resonance (EPR). Fe exists in the material coordinated with the pyrrole nitrogen of polydopamine. This coordination structure is conducive to the generation of singlet oxygen (1O 2). It is confirmed by steady-state phosphorescence spectroscopy (PH) that 1O 2 originates from electron transfer. Superoxide radicals are generated by electron transfer and then oxidized into 1O 2 by holes. The main intermediates of MBT degradation were identified by the LC-MS method, and a possible photocatalytic mechanism based on quenching experiments and EPR tests was proposed. • Fe decorated carbon nitride catalyst was synthesized by a rational and scalable method. • The coordination of Fe with pyrrolic nitrogen contributes to the generation of singlet oxygen. • C-Fe@PDA forms a new electron transfer channel. • Efficient photodegradation of 2-mercaptobenzothiazole was achieved by C-Fe@PDA-CN. [ABSTRACT FROM AUTHOR]

• The basic properties of 1O 2 are introduced. • The formation of 1O 2 and its reaction with organics are summarized. • The debatable roles of 1O 2 in PS-AOPs are discussed. • The methods and their drawbacks of 1O 2 identification are analyzed. • Prospects about the rational identification of 1O 2 are put forward. Singlet oxygen (1O 2) attracts much attention in persulfate-based advanced oxidation processes (PS-AOPs), because of its wide pH tolerance and high selectivity toward electron-rich organics. However, there are conflicts about the 1O 2 role in PS-AOPs on several aspects, including the formation of different key reactive oxygen species (ROS) at similar active sites, pH dependence, broad-spectrum activity, and selectivity in the elimination of organic pollutants. To a large degree, these conflicts root in the drawbacks of the methods to identify and evaluate the role of 1O 2. For example, the quenchers of 1O 2 have high reactivity to other ROS and persulfate as well. In addition, electron transfer process (ETP) also selectively oxidizes organics, having a misleading effect on the identification of 1O 2. Therefore, in this review, we summarized and discussed some basic properties of 1O 2 , the debatable role of 1O 2 in PS-AOPs on multiple aspects, and the methods and their drawbacks to identify and evaluate the role of 1O 2. On the whole, this review aims to better understand the role of 1O 2 in PS-AOPs and further help with its reasonable utilization. [Display omitted] [ABSTRACT FROM AUTHOR]

The selectivity of singlet oxygen (1O 2) holds promising applications in complex environmental systems due to its ability to preferentially oxidize target pollutants. Usually, 1O 2 in photocatalytic systems is generated via the electron transfer pathway and •O 2 − plays an important role as an intermediate, while the exciton-based energy transfer pathway for 1O 2 generation has been less studied. Here, a 2D Ag-γ-Fe 2 O 3 /BiVO 4 with oxygen vacancies was designed which was capable of generating 1O 2 by an exciton-based energy transfer-dominated approach, as strongly demonstrated by the results of steady-state fluorescence spectroscopy and phosphorescence spectroscopy. In the Z-type heterojunction photocatalyst system, Ag acted as an electron mediator to promote not only the generation of free carriers but also the generation of singlet excitons, while the appropriate concentration of oxygen vacancies further promotes the exciton-triggering photocatalysis production of 1O 2. The Ag-γ-Fe 2 O 3 /BiVO 4 could degrade 99.4% of sulfadiazine within 90 min, and 1O 2 played an important role in the degradation of sulfadiazine, as shown by EPR and active species capture experiments. Ecotoxicity predictions indicated that the main byproducts of sulfadiazine degradation by Ag-γ-Fe 2 O 3 /BiVO 4 were low in toxicity. The prepared photocatalysts provide a new idea for obtaining 1O 2 and designing photocatalysts with selectivity. [Display omitted] • Ag-γ-Fe 2 O 3 /BiVO 4 was prepared which efficiently photodegraded sulfadiazine. • 1O 2 was mainly produced by energy transfer, in which electrons played a weak role. • The OVs and 2D structures promoted the formation of 1O 2. • Ag provided the SPR effects and acted as an electronic mediator. [ABSTRACT FROM AUTHOR]

Photocatalytic selective oxidation of C(sp 3 )-H bonds is an attractive strategy for synthesis of high value-added products due to the property of solar-driven and mild reaction conditions. However, improving photocatalytic activity and selectivity is still a grand challenge. Herein, we systematically compared the activity and selectivity for photocatalytic oxidation of 4-phenyltoluene by using the as-prepared photocatalysts. The results demonstrated that structure control and alkali metal modification could improve photocatalytic activity and selectivity by increasing the amount of singlet oxygen (1O 2) molecules, which was proved by electron paramagnetic resonance (EPR) spectroscopy and phosphorescence (PH) spectroscopy. Moreover, no apparent decrease of conversion rate and selectivity during the 6 cycle runs indicated excellent stability of the prepared photocatalysts. This work revealed a basic mechanism on the energy transfer process of excitons and developed a feasible strategy for the design of C 3 N 4 -based photocatalysts. [Display omitted] • A novel K+ doping tubular morphology of C 3 N 4 semiconductor material was prepared by a facile self-assembly process. • The photocatalyst exhibits excellent photocatalytic performance for photocatalytic selective oxidation of 4-phenyltoluene. • The reasons of excellent performance were considered to shorten the distance from bulk to surface and enhance transfer. • This study successfully provided an effective strategy to increase the amount of 1O 2 molecules on C 3 N 4 -based photocatalysts.. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols contain organic compounds that can form triplet organics (3C*) excited by sunlight, which plays a significant role in the aging process of aerosols. The formation characteristics of 3C* of aerosol components with different polarities were investigated, including highly polar water-soluble matter (HP-WSM), humic-like substances (HULIS), and methanol-soluble matter (MSM). Carbon analysis, probe method and electron paramagnetic resonance were used to investigate the photochemical properties of ambient samples. The coupling effect of generation of 3C* and reactive oxygen species (ROS) between different aerosol components was also examined. The results showed that the 3C* generation characteristics are strongly dependent on the polarity of these components. HULIS has the strongest generation ability of 3C*, and the MSM contributes the most to the total generation of 3C*. It was found that the high-energy triplet states (E T ≥ 250 kJ mol−1) of HULIS and HP-WSM components account for up to 80% of the water soluble components. These 3C* have an important contribution to the photochemically generation of ROS, and the generated ROS of different components are also different, which is determined by the chromophore composition of complex organic compounds. A tyrosine-like chromophore is the main substance leading to the formation of water-soluble 3C*, while the highly oxidized HULIS chromophore plays a leading role in the water-insoluble component. This study also found that there is a coupling effect between HP-WSM and HULIS on 3C* and ROS generation. The generation rate of 3C* increases by about 40% after mixing, but the generation of 1O 2 is severely reduced. In general, this study provided deep insights into the generation characteristics and aging impact of the triplet state on atmospheric aerosols. [Display omitted] • 3C* generation is dependent on the polarity of aerosol components. • Aerosol HULIS has the strongest generation ability of 3C*. • The 3C* generated by HULIS are mainly high energy (E T ≥ 250 kJ mol−1). • Aerosol 3C* had an important contribution to the ROS generation. • There is a coupling effect between HP-WSM and HULIS on 3C* generation. [ABSTRACT FROM AUTHOR]

The BODIPY-Fluorene derivatives with an orthogonal conformation were prepared for the emission of efficient phosphorescence. The derivatives show visible light absorption (497–513 nm), high phosphorescence quantum efficiency (36.2%) and realize control of luminescence color from green to orange-red. Typical orthogonal conformation and smaller excited state (S 1 and T 4) energy gap (0.05 eV) are favorable for intersystem crossing (ISC) process. The calculation are carried out for rationalization between the photophysical properties and conformation of the BODIPY-Fluorene derivatives. We demonstrate that the conformational substitution positions and the distance between D-A are promising strategy to regulate the emission lifetime and quantum efficiency for BODIPY derivatives. Moreover, the ability to generate singlet oxygen was measured by photooxidation of 1,3-diphenylisobenzofuran (DPBF) by singlet oxygen (1O 2) photosensitization. At the same time, the LED device displays bright orange-red emission. This work paves the way for further research into the design and application of such materials in advanced optics. • Three new orthogonal conformation dyes based on BODIPY have been synthesized and characterized. • The effect of conformational substitution positions and the distance between D-A on properties of derivatives were studied. • The photophysical properties of BODIPY analogues studied using transient absorption spectroscopy and theoretical calculation. • The ability of the BODIPY dyes to generate singlet oxygen was explored by photooxidation of DPBF by singlet oxygen (1O 2) photosensitization. • The LED device displays bright orange-red emission. [ABSTRACT FROM AUTHOR]

The paper presents a set of experiments revealing photophysical processes associated with methylene blue assisted photodynamic inactivation of pathogens on different surfaces, both inorganic (glass) and organic (superficial fascial flaps of chicken and fish and mushroom cap peel). The experiments were performed in normoxic and hyperoxic conditions. The characteristic times of singlet oxygen generation and degradation on the surfaces were evaluated from the analysis of time-resolved signals of singlet oxygen phosphorescence. The photobleaching kinetics of methylene blue on the surfaces were found to be significantly different and dependant on solution oxygenation. The characteristic decay times varied from dozens of seconds for glass to dozens of minutes for fascial flaps and mushroom peel. The interpretation of the experimental results obtained was done on the basis of a set of master equations describing photosensitizer-assisted singlet oxygen generation and photosensitizer photobleaching. The results obtained on methylene blue photodynamics and conclusions made were compared with results of similar experiments performed earlier with Radachlorin photosensitizer. [Display omitted] • Kinetics of Methylene Blue photobleaching differ significantly on organic and inorganic surfaces. • At hyperoxic conditions photobleaching becomes noticeably faster at all the surfaces. • Singlet oxygen generation time drops significantly at hyperoxic conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The BODIPY modification have a very significant effect on the photophysical properties. • Alkyl-BODIPYs absorb at 490–535 nm and fluoresce at 500–550 nm (Ф F from 70 to 100%). • Fluorescence quantum yield of Br- and I-BODIPYs was decreased due to the "heavy atom" effect. • The attachment positions of the aryl substituents in the BODIPY determine their properties. • The NIR-BODIPYs (to 1000 nm) were obtained by meso -aza, benzo-fused and oligo-modification. The review considers the results of research by scientists from different countries in the field of synthesis and photophysical property study of known BODIPY. We focus on describing the main ways the BODIPY structure modifying by substituting the pyrrole rings, the meso -spacer, and the boron atom of the indacene core with different nature substituents and changing the spectral and other practically significant BODIPY properties associated with a particular type of their modification. In addition, we have considered the effects of alkylation, halogenation, nitration, amination, and arylation at the meso -spacer and/or pyrrole rings, boron atom; pyrrole rings annulation; meso -aza-substitution, covalent oligomerization through direct σ-bonds or spacers. Most of these approaches have a very significant and individual effect on the photophysical properties, hydrophobicity or hydrophilicity of dyes and consequently, on their practical application possibility. In the general case, BODIPY modification approaches considered above make it possible to vary the absorption and fluorescence bands position of BODIPY in the range from UV to NIR spectral regions (from 400 to 1000 nm). Depending on the features of BODIPY functionalization, as well as on the properties of the medium, the quantum yields of fluorescence, phosphorescence, and singlet oxygen generation of BODIPYs can be changed from 0 to 100%. [ABSTRACT FROM AUTHOR]

The first stable cycloheptatrienyl metal complexes bearing the CF 3 moiety were synthesized and fully characterized including by X-ray crystallographic analysis. In addition, the first DFT studies performed in trifluoromethylated and cycloheptatrienyl metal complexes were investigated. [Display omitted] Thermally stable cycloheptatrienyl metal complexes bearing the trifluoromethyl moiety are reported for the first time. While the syntheses, properties and structural characterizations of transition metal complexes of the type [(η5–C 5 H 5)ML n CF 3 ] are well known in organometallic chemistry, analogous chemistry of the elusive [(η7–C 7 H 7)ML n CF 3 ] complexes was just recently disclosed by the syntheses of Mo complexes such as [(η7–C 7 H 7)Mo(CO)(PMe 3)CF 3 ] (I). Nevertheless, complex I and similar complexes were found to be of extreme thermal instability, indicative in the fact that their purification and isolations require low temperature chromatography. Advancing past the stability hindrance, we report herein the syntheses of the W complexes [(η7-C 7 H 7)W(CO) 2 CF 3 ] (II), and [(η7–C 7 H 7)W(CO)(PMe 3)CF 3 ] (III), which are found to be indefinitely thermally stable, a fact that allowed the study of complex II by X-ray crystallography. In addition, the first DFT studies on I-III , as well as their η5–C 5 H 5 analogues, were performed both in the gas phase and with the implicit diethyl ether effects included, the structures, energetics, NBO charges, and frontier MOs were investigated. For the η7-C 7 H 7 -complexes, the metal change from Mo to W was shown to significantly increase the singlet–triplet energy difference, whereas for the η5-C 5 H 5 -complexes the metal change essentially has no effect on this difference, which is in line with the experimental findings. Comparison of the calculated structure of complex II with its X-ray structure showed quite reasonable agreement with the experimental data. The negative NBO charges on W in the C 5 H 5 -complexes were calculated to be significantly lower than in the C 7 H 7 -complexes, which again is completely in line with the stability profile of the complex. [ABSTRACT FROM AUTHOR]

Abstract: Spectral- and time-resolved infrared phosphorescence set-up was adapted for detection from surfaces of solid samples by utilizing fiber optics. Its abilities are demonstrated on the detection of singlet oxygen photosensitization by intrinsic (protoporphyrin IX synthesized from ALA) and extrinsic (TPPS4 and TMPyP) photosensitizers in in vitro layers of cultured 3T3 murine fibroblasts and HeLa cells mimicking in vivo tissues. Complex decays of phosphorescence of the photosensitizers were detected. The data were approximated by multi-exponential decays, however, no straightforward explanation of the individual components was found. Singlet oxygen phosphorescence kinetics were obtained with rise-times corresponding to singlet oxygen lifetimes ranging from to and single-exponential decay times between and for different photosensitizers and cell lines. [Copyright &y& Elsevier]

Three different molecular designs based on BODIPY dye have been proposed as photosensitizers (PSs) for photodynamic therapy (PDT) by the inclusion of halogen atoms (Iodine) at 2,6-positions and with extended conjugation at 3, 5-positions and varying the substitution at meso position. The synthesis is described and their main photophysical features including singlet oxygen production and triplet states were characterized by absorption and fluorescence spectroscopy (steady-state and time-correlated) and nanosecond transient absorption spectroscopy. The results were compared with the commercial Chlorin e6. The three new red-halogen-BODIPYs showed a great balance between singlet oxygen generation (Φ Δ ≥0.40) and fluorescence (Φ fl ≥0.22) for potential application on PDT, and particularly in theragnosis. In vitro experiments in HeLa cells were done to study their performance and to elucidate the best potential candidate for PDT. [Display omitted] • Design and characterization of new red-haloBODIPYs as theragnostic agents in PDT. • Substitution pattern at meso position controls the cellular uptake of PS. • High phototoxic action against HeLa cells has been reached (EC 50 = 10 nM). • Better performance under light irradiation than the commercial Chlorine e6 without any cytotoxicity in dark conditions. [ABSTRACT FROM AUTHOR]

Abstract: The photo-destabilizing action of 1,3,5,7,8-pentamethylpyrromethene difluoroborate complex (PM546) on 1,3,5,7,8-pentamethyl-2,6-diethylpyrromethene difluoroborate complex (PM567) and 1,3,5,7,8-pentamethyl-2,6-di-t-butylpyrromethene difluoroborate complex (PM597) has been investigated. Acetonitrile solutions of PM567 and PM597 demonstrated accelerated photodegradation upon the addition of PM546; whereas the photodegradation rate of the corresponding n-hexane solutions remained invariant with respect to PM546 addition. The enhanced photodegradation rate is explained by electron transfer from PM567 and PM597 to PM546. A PM546 singlet oxygen (1O2, O2 (a 1Δg)) quenching rate constant of 3.86±0.18 (2σ)×107 dm3 mol−1 s−1 is obtained from infrared phosphorescence measurements of O2 (a 1Δg →X3Σg −). [Copyright &y& Elsevier]

• UV/chlorine treatment significantly decreased the absorbance of the selected DOM. • Formation of hydroxylated or chlorinated products decreased the Φ RIs of DOM. • Formation of aromatic ketone or quinone increased the Φ RIs of DOM. • DOM more efficiently promote photodegradation of BZF after UV/chlorine treatment. Dissolved organic matter (DOM) is a ubiquitous component in effluents, DOM discharged with an effluent can affect the composition and properties of natural DOM in the receiving waters. As the photophysical and photochemical properties of effluent DOM can be changed by wastewater treatment processes, the effect of UV/chlorine treatment on the photophysical and photochemical properties of DOM was investigated using Suwannee River fulvic acid (SRFA) and Suwannee River natural organic matter (SRNOM) as representatives. Results showed that the absorbance of the two DOM was significantly decreased. The evolution trends of three representative photophysical parameters upon increase of chlorine dosages were observed. Also, a decrease in DOM aromaticity, molecular weight and electron-donating capacity was observed upon increasing chlorine dosage. Quantum yields of excited triplet state of DOM (3DOM*), singlet oxygen (1O 2) and hydroxyl radicals (· OH) first decreases and then increased in the UV/chlorine systems upon increasing chlorine dosages due to the different reaction pathways of the two DOM. Moreover, 3DOM* can not only be regarded as a "controller" of other reactive intermediates, but also effectively promote the photodegradation of bezafibrate, which is classified as a persistent organic contaminant. This study gives deep insights into effects of UV/chlorine on the photophysical and photochemical properties of DOM, and is helpful for understanding the dynamic roles of DOM in the photodegradation of micropollutants. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Caption: Schematic presentation of transitions between singlet and triplet excitonic state along with the lifetimes of corresponding excitonic states for PtOEP and ZnOEP nanoaggregates. The singlet exciton has been compared as rabbit which it can diffuse fast but undergoes fast deactivation. On other hand, triplet exciton is like tortoise which exist long period of time but diffuse very slowly. • Efficient singlet to triplet transitions with time constants of 9 ps and 0.8 ps for both ZnOEP and PtOEP NAs, respectively. • Triplet diffusion coefficients are estimated following analysis triplet-triplet annihilation mediated kinetics. • Estimated triplet exciton diffusion coefficients are 2-3 order smaller than that of the commonly reported singlet excitons. • Involvement of short range, exchange mechanism-based energy transfer process results slow diffusion of triplet excitons. • Presence of singlet-triplet cooperative diffusion mechanism results ∼4.3 time faster triplet diffusion in ZnOEP NAs. J-type nanosized-aggregates (NA) of zinc and platinum-octaethylporphyrin (ZnOEP and PtOEP) are prepared and observed to undergo fast triplet formation via inter system crossing (ISC) process. The ultrafast transient absorption measurement of ZnOEP NA indicates fast decay of singlet excitonic state with the lifetime of ∼9 ps. On other hand, the singlet decay rate is even faster for PtOEP NA, having lifetime value of ∼0.8 ps. Singlet excitonic decays cause subsequent population of triplet states which possess long annihilation free lifetimes of 1.7 and 0.6 ms for ZnOEP and PtOEP NA, respectively. However, at high exciton densities the triplet excitons are observed to decay via triplet-triplet annihilation (TTA) and their natural radiative, non-radiative decay processes. The exciton density dependent triplet decay dynamics further analyzed to estimate TTA rate constants and exciton diffusion parameters. The triplet exciton diffusion coefficient values thus obtained are 4.06 × 10−7 and 0.94 × 10−7 cm2 s-1 for ZnOEP and PtOEP NAs, respectively. The diffusion coefficients possess nearly two order smaller values as compared to those of the commonly reported singlet excitons. Involvement of spin exchange based short range transfer mechanism of triplet exciton make this diffusion process slower. However, the possible involvement of singlet-triplet cooperative diffusion mechanism results ∼4.3 time faster triplet diffusion in ZnOEP NAs as compared to that of the PtOEP NAs. The slow exciton diffusion properties of triplet enhance the importance of requirement of long triplet lifetime to obtain an elongated triplet diffusion length. These two nanoparticles are observed to fulfill the long lifetime criteria and own reasonably long triplet diffusion lengths which may be beneficial for solar cell, photon up-conversion and singlet oxygen generation based applications. [ABSTRACT FROM AUTHOR]

• The two-photon (TP) photosensitizers (PS) of maximum absorption at 808 nm and maximum fluorescence at 660 nm can be potential for deep-seated tumor imaging and therapy. • The boron dipyrromethene (BDP) structure used in TP photodynamic therapy (PDT) possess favorable photophysical property (i.e. , high molar extinction coefficients, superior fluorescent quantum yields, outstanding photo stability), and the indo-BDP in meso-position can efficiently improve the singlet oxygen quantum yield (0.39). • The cationic group in TP PS can efficiently improve the PDT efficacy (IC50=25.5 nM) compared with two neutral contrastive molecules (PG-Car-BDP and C 10- Car-BDP). • The cationic PS TP-Car-BDP can efficiently target to tumor in vivo due to the structure inherent targeting. Two-photon (TP) have been innovatively researched in bio-imaging and photodynamic therapy (PDT) due to the near-infread (NIR) absorption and excellent spatial accuracy, especially for the subcutaneous and deep-seated tumor. For TP excited photosensitizers (PS), the NIR absorption and enough triplet state energy can be simultaneously realized by semi-excited mode. Thus, we reported a boron dipyrromethene based cationic two-photon photosensitizer (TP-Car-BDP) to promote the tumor targeting and optical physical properties for better imaging and therapeutic effect, using two neutral molecules (PG-Car-BDP, C 10 -Car-BDP) as comparison. As expected, the cationic group could accelerate oil-water balance and cellular uptake, realize structure-inherent targeting in vivo , and induced early apoptosis in PDT. The imaging and therapeutic property of TP-Car-BDP excited by one/two-photon was also compared to illustrate efficacy of TP. Moreover, the high singlet oxygen quantum yield (0.39) and excellent phototoxicity (IC 50 of 25.5 nM, MB was 2960 nM) revealed the potential therapeutic capacity. [ABSTRACT FROM AUTHOR]