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Understanding the microenvironment structure‐activity relationship of singlet‐atom catalysts (SACs) is imperative for the development of high‐performance photocatalytic devices. However, the challenge remains to finely regulate the coordination microenvironment of SACs. Herein, single‐atom Nx─Cu─O4‐x (x = 1–4) photocatalysts with different coordination environments are successfully prepared based on pre‐design reticular supramolecular covalent organic frameworks (COFs) for direct photocatalytic 1O2 production from O2. The results show that the high activity of Cu SACs is closely related to the N,O‐coordination microenvironment, which is primarily ascribed to the different electrophilicity of the N, O atom. The electron configuration of N3‐Cu‐O1 endows photocatalyst enhanced charge transfer capability and the nearest D‐band center to the Fermi level. The "end‐on" type adsorption configuration of O2 at the N3─Cu─O1 active site can promote the breaking of Cu─O bonds rather than O─O bonds. As a result, the N3‐Cu‐O1@COF photocatalyst exhibits the most optimal formation and desorption energies for intermediates •OOH, which provides an advantageous reaction pathway with fewer steps and a lower barrier for 1O2 production. This work highlights the structure‐activity relationship of SACs for long‐term applications. [ABSTRACT FROM AUTHOR]

The synthesis of molecular host–guest complexes with enhanced performance, relative to those of their components, is a central theme in supramolecular chemistry. Here we explore a host‐guest system consisting of an atomically precise gold nanocluster bound inside a zinc porphyrin nanoring. UV/Vis absorption and fluorescence titrations with different sized nanorings revealed strong binding between a pyridinethiol‐coated Au25 nanocluster and a nanoring consisting of six zinc porphyrin units, and complexation is confirmed by mass spectrometry. Formation of this assembly enhances the stability of the gold nanocluster. The host‐guest complex also exhibits remarkable activity and selectivity for photochemical CO2 to CO conversion and singlet oxygen generation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Enhanced charge separation by phosphate modification result in H 2 O 2 oxidation by HClO but weaken excitonic effect in B001. • B010 with poor excitons generate 1O 2 via O 2 − oxidation, enhanced 1O 2 yielding in P-B010 was due to H 2 O 2 oxidation by HClO. • CBZ degradation efficiency enhanced by 1.3 and 2.2 times over B001 and B010 after phosphate modification, respectively. • The initial attack of C C bond via 1O 2 to form epoxide played important roles on CBZ degradation. 1O 2 generation over (0 0 1) or (0 1 0) facet exposed BiOCl (B001 or B010) with/without phosphate modification were studied from the aspects of excitons involved energy transfer route, the O 2 − oxidation based charge transfer route and the H 2 O 2 oxidation by HClO. Phosphate modification not only enhance charge separation thus result in H 2 O 2 oxidation by HClO to release 1O 2 but also weaken excitonic effect in the confined layer of BiOCl accordingly affect 1O 2 generation via energy transfer. Considering [0 0 1] orientation favors the formation of excitons than that of [0 1 0] direction over BiOCl, excitons loss was hardly compensated by the H 2 O 2 oxidation by HClO for 1O 2 generation over phosphate modified B001. Nevertheless, limited excitonic effect makes the O 2 − oxidation by h+ via charge transfer as dominant route for 1O 2 yielding over B010, the extra H 2 O 2 oxidation with HClO after phosphate modification significantly enhance 1O 2 generation over B010 followed with 2.2 times higher carbamazepine photodegradation activity. The initial attack of C C bond via 1O 2 to form epoxide played important roles on carbamazepine degradation. This study demonstrated that the facet-specific phosphate modification of photocatalysts can finely tune reactive 1O 2 species for superior pharmaceuticals degradations. [ABSTRACT FROM AUTHOR]

We reported herein the synthesis, characterization of hybrid conjugates composed of phthalimide (Phth) and acridine-1,8-diones (Acr) for optical and medical applications. For the synthetic procedure, a three-step synthetic strategy has been utilized. The optical properties of the examined 1,8-acridinedione–phthalimide connected molecules (AcrPhth 1–5) have been examined utilizing various spectroscopic techniques, e.g., steady-state absorption and fluorescence, and time-correlated single photon counting. The steady-state absorption studies showed that AcrPhth 1–5 absorbs the light in the UV and visible region. The fluorescence studies of AcrPhth 1–5 exhibited significant fluorescence quenching compared to the acridinedione control compounds (Acr 1–5) suggesting the occurrence of electron-transfer reactions from the electron donating acridinedione moiety (Acr) to the electron accepting phthalimide moiety (Phth). The rate and efficiency of the electron-transfer reactions were determined from the fluorescence lifetime measurements indicating the fast electron-transfer processes of the covalently connected AcrPhth 1–5 conjugates. Computational studies supported the intramolecular electron-transfer reaction of AcrPhth conjugates using ab initio B3LYP/6-311G methods. In the optimized structures, the HOMO was found to be entirely located on the Acr entity, while the LUMO was found to be entirely on the Phth entity. Further, the synthesized compounds were tested as photosensitizers for generating the singlet oxygen species, which is a key factor in the photodynamic therapy (PDT) applications. The nanosecond laser flash measurements enable us to detect the triplet-excited states of examined Acr and AcrPhth conjugates, determining the triplet quantum yields, and direct detecting the singlet oxygen in an accurate way. From this observation, the singlet quantum yields were found to be in the range of 0.12–0.27 (for Acr 1–5) and 0.07–0.19 (for AcrPhth 1–5 conjugates). The molecular docking studies revealed that compound AcrPhth 2 exhibited high binding affinity with for key genes (p53, TOP2B, p38, and EGFR) suggesting its potential as a targeted anticancer therapy. [ABSTRACT FROM AUTHOR]

Photoswitching materials have emerged as a promising class of compounds that possess manifold interesting properties rendering their widespread use from photoswitches, regulators to optoelectronic devices, security technologies and biochemical assays. Diarylethenes (DAE) constitute one such category of photoswitchable compounds, where the key features of stability, photoisomerization wavelengths, quantum yield and variability in the photoisomers significantly depend on their derivatization. The last decade has witnessed a surge in the engagement of DAEs in different areas of chemical and biological sciences, like biomarkers, controlled generation of singlet oxygen, photo‐dynamic therapy, chemosensing, catalysis, etc. In all the cases, the photoswitchability of DAE is the principal regulating factor along with its emission properties according to the appended groups. Previous reviews on applications of DAE‐based systems did not predominantly cover all the aspects of biological and industrial implementations. They have covered only one field of application either in the biological science or in the synthetic aspect or photochromic aspects only. This review is a coalition of all those aspects in last six years. Here the variation of properties of the DAE systems with respect to structural diversifications have been discussed in detail along with their potential applications in bioimaging of cells, regulating singlet oxygen generation for photodynamic therapy and catalysis of organic reactions, and their future prospects. A tabular presentation of the photophysical properties of DAE derivatives adds to the basic understanding of this subject at a glance. We hope that this cumulative collection of contemporary research on DAE, as presented in this review, will enhance the knowledge of the readers about synthetic design anticipating their properties well in advance, and will certainly motivate researchers to generate new DAE architectures with superior chemical and biological properties in future. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a well-established and extensively studied photosensitizer for photodynamic therapy (PDT), since it can generate singlet oxygen with a high quantum yield upon irradiation within the phototherapeutic (600–950 nm) window. However, its activity can decrease due to the formation of dimers or higher aggregates, which can take place in an aqueous solution at relatively high concentrations. The incorporation of this molecule into a matrix can avoid this aggregation and increase its activity relative to PDT. Silica porous nanoparticles are chosen here as a matrix to host MB. The size and pore geometry are tuned in order to decrease MB leaching while maintaining good singlet oxygen generation and colloidal stability for further applications in nanomedicine. In addition, phenyl functions are grafted on the pores of the silica matrix in order to avoid MB aggregation, thereby increasing the activity of the photosensitizer in the singlet oxygen generation. DFT calculations give insight in the structure of the aggregation of the MB units, and the roles of water and organic environments are investigated through time-dependent calculations on UV-vis spectra. [ABSTRACT FROM AUTHOR]

A series of mononuclear ruthenium(II) tetra-tert-butyl-phthalocyaninates bearing axial N-donor ligands [tBu4PcRu]L2 (L = trimethylamine, pyrazine, 4,4′-bipyridine and N-methyl-4,4′-bipyridinium iodide) as well as the binuclear complex [tBu4PcRu]2(BiPy)3 were synthesized starting from the complex with axially coordinated carbonyl group [tBu4PcRu](CO). All compounds have been characterized by NMR, UV-Vis and cyclic voltammetry. The latter allowed the determination of oxidation and reduction potentials, HOMO-LUMO gaps and revealed the possibility of electropolymerization of BiPy-containing complexes in clear contrast to complexes containing another bidentate ligand – pyrazine. Comparative electrochemical studies of the mono- and binuclear complexes [tBu4PcRu](BiPy)2 and [tBu4PcRu]2(BiPy)3 revealed that the phthalocyanine rings are not conjugated in the binuclear species. The remarkable dependence of singlet oxygen generation from axial ligands in ruthenium phthalocyaninates was observed: the complexes with carbonyl group [tBu4PcRu](CO) and with pyrazine molecules [tBu4PcRu](Pyz)2 show higher 1O2 quantum yields, whereas the complex with axially coordinated molecules of trimethylamine [tBu4PcRu](NMe3)2 and quaternized BiPy ligands [tBu4PcRu](BiPy-Me+)2 have the lowest ability to generate singlet oxygen. The revealed influence of axial ligands on key physicochemical properties paves the way for the design of new ruthenium phthalocyaninates with potential optoelectronic and biomedical applications. [ABSTRACT FROM AUTHOR]

ABSTRACTA series of porous organic polymers based on a singlet oxygen generating oxoporphyinogen (‘OxP’) has been successfully prepared from a pseudotetrahedral OxP-tetraamine precursor (OxP(4-NH2Bn)4) by its reaction with tetracarboxylic acid dianhydrides under suitable conditions. Of the compounds studied, those containing naphthalene (OxP-N) and perylene (OxP-P) spacers, respectively, have large surface areas (~530 m2 g−1). On the other hand, the derivative with a simple benzene spacer (OxP-B) exhibits the best 1O2 generating capability. Although the starting OxP-tetraamine precursor is a poor 1O2 generator, its incorporation into OxP POPs leads to a significant enhancement of 1O2 productivity, which is largely due to the transformation of NH2 groups to electron-withdrawing diimides. Overall 1O2 production efficacy of OxP-POPs under irradiation by visible light is significantly improved over the common reference material PCN-222. All the materials OxP-B, OxP-N and OxP-P promote oxidation of thioanisole involving conversion of ambient triplet state oxygen to singlet oxygen under visible light irradiation and its reaction with the sulfide. Although the reaction rate of the oxidation promoted by OxP POPs is generally lower than for conventional materials (such as PCN-222) or previously studied OxP derivatives, undesired overoxidation of the substrate to methyl phenyl sulfone is suppressed. For organic sulfides, selectivity of oxidation is especially important for detoxification of mustard gas (bis(2-chloroethyl)sulfide) or similarly toxic compounds since controlled oxidation leads to the low toxicity bis(2-chloroethyl)sulfoxide while overoxidation leads to intoxification (since bis(2-chloroethyl)sulfone presents greater toxicity to humans than the sulfide substrate). Therefore, OxP POPs capable of promoting selective oxidation of sulfides to sulfoxides have excellent potential to be used as mild and selective detoxification agents.

The paper reports on the synthesis and evaluation of photochemical properties of gold nanorods (Au−NRs) coated with PEG with a thiol (−SH) group or SiO2 and their physical mixtures with pheophorbide a. Also biological activity of these systems was tested in photodynamic therapy directed towards Staphylococcus aureus. The potential additive effect between differently functionalized Au−NRs and the dye pheophorbide a was also studied. The efficiency of singlet oxygen generation varied considerably depending on the type of PEG polymer used for coating NRs and was the highest, of 65%, for the polymer PEG (10k) and the Au−NRs concentration of (1.33×10−11 M). For the other studied PEGs (2k, 5k) and the same concentration of NRs, a decrease in the singlet oxygen generation efficiency was observed. The most effective against Gram‐positive bacteria were the mixtures of PEG‐coated Au−NRs with pheophorbide a, exposed to irradiation at 405 nm and 660 nm, which provided a >5.8 log reduction in the bacteria growth. However, no strong bactericidal effect was noted in the case of irradiation with 525 nm. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a photochemical‐based treatment approach that involves using light to activate photosensitizers (PSs). Attractively, PDT is one of the alternative cancer treatments due to its noninvasive technique. By utilizing the heavy atom effect, this work modified a class of formazan dyes to improve intersystem crossing (ISC) to improve reactive oxygen species (ROS) generation for PDT treatment. Two methods were used to observe the ROS generation enhanced by ISC of the synthesized complexes including, (1) recording DPBF decomposition caused by the ROS, and (2) calculating the potential energy curves for photophysical mechanisms of BF2‐formazanate dyes using the DFT and nudged elastic band (NEB) methods. The photophysical properties of the dyes were studied using spectroscopic techniques and X‐ray crystallography, as well as DFT calculations. The experimental and theoretical results and in vitro cellular assays confirmed the potential use of the newly synthesized iodinated BF2‐formazanate dyes in PDT. [ABSTRACT FROM AUTHOR]

An azadipyrromethene ligand (H1) and homoleptic zinc(II) (H1-Zn) complex were synthesized. The resulting structures were elucidated by NMR, FTIR, and HRMS techniques. The photophysical properties and effects of complexing the zinc(II) atom to azadipyrromethene ligands in solution were studied by means of UV-Vis absorption and fluorescence spectroscopy. Experimental findings were elucidated using density functional theory computations and interfragment charge transfer (IFCT) and electron-hole analyses. The fluorescence features were found to be negligible. The ligand molecule decayed at a rate of 3% while the complex decayed at 2% upon photoirradiation based on photostability experiments. The singlet oxygen quantum yields of the ligand and complex were calculated as 0.127 and 0.233, respectively, signifying low photodynamic activity. The charge transfer transitions were determined between reciprocal ligands responsible for the red shift of the main absorption band by IFCT and electron-hole analysis. Compounds in an inert N2 atmosphere demonstrated high thermal stability. Although the thermogravimetric analysis (TGA) and derivative thermogravimetry curves of the complexes were similar, zinc(II) coordination and homoleptic complex formation reduced the degradation temperatures. These findings suggest that azadipyrromethene and the Zn(II) class of chromophores have beneficial features for use in the development of novel photo- and thermostable materials that combine charge transfer with low energy in the visible and near infrared regions. [ABSTRACT FROM AUTHOR]

Multidrug resistance of pathogenic microflora is a serious threat to the modern community looking for new approaches to treating superinfections. In this sense, antimicrobial photodynamic therapy (aPDT) is an effective and safe technique considered to be a promising alternative or an important supplement to the traditional clinically applied methods for inactivating antibiotic resistant pathogens. Macroheterocyclic photosensitizers (PS) of three generations are proposed for clinical practice. They are known as the key compounds for PDT able to be localized selectively in microbial cells and to be activated with the red light producing toxic reactive oxygen species (ROS). However, these neutral and anionic PSs possess low affinity towards the outer lipopolysaccharide membrane of Gram-negative bacteria and, consequently, poor ability to kill these pathogens under irradiation. In contrast, cationic PSs containing one or more charged groups, especially those bound to an appropriate carrier, provide efficient inactivation of microorganisms. In this paper, we focus on the study of photophysics, aggregation and photoinduced antimicrobial activity of the water-soluble derivative of deuteroporphyrin-IX, a blood group porphyrin, bearing two cationic trialkylammonium fragments. This potential photosensitizing agent is found to generate singlet oxygen in a non-polar environment and forms stable nano-sized molecular complexes with passive non-ionic carrier Tween 80, localizing in an aqueous surfactant solution as a non-aggregated form in the surface micellar layer. Two different modes of PS/Tween 80 binding characterized by their own stability constants and interaction stoichiometry are observed. Microbiological experiments clearly demonstrate that the increased permeability of the outer bacterial membrane caused by the application of the intramicellar form of the photosensitizer or addition of some potentiation agents leads to pronounced light phototoxicity of the pigment against antibiotic-resistant nosocomial strains of Gram-negative bacterial pathogens.

Methylene blue (MB) is a well-established and extensively studied photosensitizer for photodynamic therapy (PDT), since it can generate singlet oxygen with a high quantum yield upon irradiation within the phototherapeutic (600–950 nm) window. However, its activity can decrease due to the formation of dimers or higher aggregates, which can take place in an aqueous solution at relatively high concentrations. The incorporation of this molecule into a matrix can avoid this aggregation and increase its activity relative to PDT. Silica porous nanoparticles are chosen here as a matrix to host MB. The size and pore geometry are tuned in order to decrease MB leaching while maintaining good singlet oxygen generation and colloidal stability for further applications in nanomedicine. In addition, phenyl functions are grafted on the pores of the silica matrix in order to avoid MB aggregation, thereby increasing the activity of the photosensitizer in the singlet oxygen generation. DFT calculations give insight in the structure of the aggregation of the MB units, and the roles of water and organic environments are investigated through time-dependent calculations on UV-vis spectra.

Construction of metal–organic cages with unique architecture and guest binding abilities is highly desirable. Herein, we report the synthesis of a distorted trigonal cage (1) from a twisted tetratopic ligand (L) and a PdII acceptor. Surprisingly, 1 exhibited a complete structural reorganization of its building units in the presence of C70 and C60 to form guest‐encapsulated tetragonal cages, (C70)2@2 and (C60)2@2, respectively. These guest‐bound cages were found to be potential 1O2 generators, with the former effectively catalyzing two different varieties of 1O2‐mediated oxidation reactions. [ABSTRACT FROM AUTHOR]

In the event of a public health crisis, highly effective and sustainable antimicrobial materials and equipment will be urgently needed. Here, the preparation is reported by electrospinning of broad‐spectrum antibacterial nanofibers embedded in a photoactive hydrogen‐bonded organic framework (HOF) of rod‐like nanocrystals ≈60 nm in length. The resulting HOF@PVDF‐HFP nanofibers maintain excellent tensile and breathability characteristics while shielding HOF nanocrystals against acid and alkali corrosion. A series of nanofibers embedded with different amounts and types of HOF nanocrystals are prepared to optimize their efficiency of singlet oxygen (1O2) generation. The 0.5 wt.% HOF‐101‐F@PVDF‐HFP nanofibers exhibit the most efficient 1O2 generation that is enhanced by a factor of almost 2 when compared with the HOF‐101‐F microcrystalline powder. The HOF@PVDF‐HFP nanofibers are demonstrated to highly effectively kill pathogens, including viruses, bacteria, and fungi in 30 min under ambient light conditions. [ABSTRACT FROM AUTHOR]

Multidrug resistance of pathogenic microflora is a serious threat to the modern community looking for new approaches to treating superinfections. In this sense, antimicrobial photodynamic therapy (aPDT) is an effective and safe technique considered to be a promising alternative or an important supplement to the traditional clinically applied methods for inactivating antibiotic resistant pathogens. Macroheterocyclic photosensitizers (PS) of three generations are proposed for clinical practice. They are known as the key compounds for PDT able to be localized selectively in microbial cells and to be activated with the red light producing toxic reactive oxygen species (ROS). However, these neutral and anionic PSs possess low affinity towards the outer lipopolysaccharide membrane of Gram-negative bacteria and, consequently, poor ability to kill these pathogens under irradiation. In contrast, cationic PSs containing one or more charged groups, especially those bound to an appropriate carrier, provide efficient inactivation of microorganisms. In this paper, we focus on the study of photophysics, aggregation and photoinduced antimicrobial activity of the water-soluble derivative of deuteroporphyrin-IX, a blood group porphyrin, bearing two cationic trialkylammonium fragments. This potential photosensitizing agent is found to generate singlet oxygen in a non-polar environment and forms stable nano-sized molecular complexes with passive non-ionic carrier Tween 80, localizing in an aqueous surfactant solution as a non-aggregated form in the surface micellar layer. Two different modes of PS/Tween 80 binding characterized by their own stability constants and interaction stoichiometry are observed. Microbiological experiments clearly demonstrate that the increased permeability of the outer bacterial membrane caused by the application of the intramicellar form of the photosensitizer or addition of some potentiation agents leads to pronounced light phototoxicity of the pigment against antibiotic-resistant nosocomial strains of Gram-negative bacterial pathogens. [ABSTRACT FROM AUTHOR]

A novel amphiphilic cationic chlorin e6 derivative was investigated as a promising photosensitizer for photodynamic therapy. Two cationic –N(CH3)3+ groups on the periphery of the macrocycle provide additional hydrophilization of the molecule and ensure its electrostatic binding to the mitochondrial membranes and bacterial cell walls. The presence of a hydrophobic phytol residue in the same molecule results in its increased affinity towards the phospholipid membranes while decreasing its stability towards aggregation in aqueous media. In organic media, this chlorin e6 derivative is characterized by a singlet oxygen quantum yield of 55%. Solubilization studies in different polymer- and surfactant-based supramolecular systems revealed the effective stabilization of this compound in a photoactive monomolecular form in micellar nonionic surfactant solutions, including Tween-80 and Cremophor EL. A novel cationic chlorin e6 derivative also demonstrates effective binding towards serum albumin, which enhances its bioavailability and promotes effective accumulation within the target tissues. Laser confocal scanning microscopy demonstrates the rapid intracellular accumulation and distribution of this compound throughout the cells. Together with low dark toxicity and a rather good photostability, this compound demonstrates significant phototoxicity against HeLa cells causing cellular damage most likely through reactive oxygen species generation. These results demonstrate a high potential of this derivative for application in photodynamic therapy. [ABSTRACT FROM AUTHOR]

Naphthalimide substituted SiPc was designed/synthesized, and photophysicochemical and biological properties of this compound were investigated comparatively for the first time. This new dye is the first examples of the symmetric Pc -naphthalimide combination with axial naphthaimide substitution. Also, all of the studied properties of the compound were compared Zn(II) and Ga(III) derivatives bearing peripheraly naphthalimide groups. [Display omitted] A new Si(IV) phthalocyanine (Pc) (1) derivative comprising axially phenoxy-bearing naphthalimide and peripherally t -butyl groups was synthesised and the photophysicochemical properties of this compound were investigated as an antioxidant and antimicrobial agent. Furthermore, the biological properties of the Si(IV) Pc compound (1) and its Zn(II) and Ga(III) Pc derivatives with a peripherally attached phenoxy-bearing naphthalimide group(2 and 3) were assessed in this study. While these compounds exhibited moderate antioxidant effects, their DNA nuclease activities were highly satisfactory. The compounds demonstrated effective antimicrobial activity, particularly following the photodynamic therapy. The most effective minimum inhibitory concentration value was obtained as 4 mg/L against E. faecalis and S. aureus. All compounds inhibited 100 % microbial cell viability at 125 mg/L. The biofilm formation ability of P. aeruginosa and S. aureus was significantly inhibited by all of the Pc compounds. Furthermore, experimental data were supported by TD-DFT calculations and NTO analyses, and the orbital densities of the compounds were shown. [ABSTRACT FROM AUTHOR]

A comparative mechanistic study on the photocatalytic activity of the free base and core and/or peripheral protonated meso -tetra(2-, 3- and 4-pyridyl)porphyrins is reported. While the diprotonated derivatives with dichloroacetic acid and HCl are water insoluble, the hexaprotonated species are stable water-soluble photosensitizers, applicable for aqueous aerobic oxidation of organic compounds. Oxidation of 1,3-diphenylisobenzofuran (DPBF) to 1,2-dibenzoylbenzene (DBB) was used to determine the kinetics parameters and singlet oxygen quantum yields. [Display omitted] • Substituent effects on the photocatalytic activity of meso -tetra(pyridyl)porphyrins. • Singlet oxygen generation efficiency of diprotonated and hexaprotonated derivatives. • Porphyrin photosensitizers with highly red shifted and/or intensified absorption bands. • Hexaprotonated meso -tetra(pyridyl)porphyrins as water soluble photosensitizers. • Strong acid catalysis in the aerobic photooxidation of methyl phenyl sulfide. The aerobic photooxidation of 1,3-diphenylisobenzofuran (DPBF) as a specific singlet oxygen quencher was studied in the presence of meso -tetra(aryl)porphyrins (aryl = 2-pyridyl, 3-pyridyl and 4-pyridyl) and their diprotonated and hexaprotonated derivatives to investigate the influence of the position of pyridine nitrogen atom, solvent, core protonation (with HCl or dichloroacetic acid) and full protonation of the porphyrins on their photocatalytic activity and photooxidative stability. The pseudo-first order rate constants (k obs) for the oxidation of DPBF with singlet oxygen were determined to compare the relative activity of the photosensitizers. 1,4-benzoquinone as a scavenger of superoxide anion radical provided evidence for the absence of this species in these photocatalytic systems. The singlet oxygen quantum yields (φ Δ) of the porphyrin photosensitizers were estimated by determining the initial rate constants for the oxidation of DPBF. H 4 T(2-Py)P(Cl) 2 and H 4 T(2-Py)P(CHCl 2 COO) 2 were the most efficient photosensitizers of the series of the meso -tetra(2-, 3- or 4-pyridyl)porphyrins and the protonated derivatives. [ABSTRACT FROM AUTHOR]

• Structural modifications of BODIPY-3,5-dicarboxylates at 1,7-position were carried out for fine tuning their properties. • The influence of 1,7-substituents on their photophysical and electrochemical properties, as well as photostability was studied. • DFT calculations revealed relationship between structural features and photophysical properties of these BODIPYs. A comprehensive evaluation of 2,6,8-triphenyl-BODIPY-3,5-dicarboxylates was carried out to reveal the effect of substitution at 1,7-positions on properties of this structural type of BODIPY. For this purpose, a series of different 1,7-substituted ethyl 2,6,8-triphenyl-BODIPY-3,5-dicarboxylates (unsubstituted 3a, difluoro- 3b, dimethyl- 3c and dichloro- 3d) was synthesized. The resulting BODIPYs were characterized by UV–visible and fluorescence spectroscopies, cyclic voltammetry and DFT calculations. In addition, their ability to generate singlet oxygen and photostability were evaluated. The data from this investigation are summarized, compared, analyzed and discussed herein. It was found that 1,7- dimethyl derivative 3c is the most promising photosensitizer for further application in the context of balance between photophysical properties and photostability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The feasibility of employing Pt-TPP as a substitute for porphyrin in studying the singlet oxygen generation proportion from triplet state in water was explored and confirmed. • A first-order decay model of the excited triplet states for Pt-TPP was constructed and confirmed. • The total transition rate of the T 1 state (A 0) value under pure water content was predicted to be 0.021 μs−1. • Combined with A 0 and the quenching rate constant of T 1 by O 2 (k q), the formula for R in relation to changes in oxygen can be deduce. The proportion of singlet oxygen (R) produced from the triplet state of porphyrin in aqueous solutions was investigated by substituting porphyrin molecules with the metalloporphyrin Platinum(II) meso -tetraphenylporphyrin (Pt-TPP). The feasibility of using platinum porphyrin as a substitute for porphyrin to study the photophysical properties in photodynamic therapy (PDT) was confirmed. The model of first-order decay in a water-methanol mixed solution encompasses potential deactivation processes of the excited triplet states and was built, which was confirmed by monitoring the change in the total transition rate of the T 1 state (A 0) value at different water contents under anoxic environments, obtained through measuring the phosphorescence lifetime (τ p) of Pt-TPP. Combined with A 0 and the quenching rate constant of T 1 by O 2 (k q), the formula for R in relation to changes in oxygen can be deduced in pure water. [ABSTRACT FROM AUTHOR]

Tuning the amphiphilicity of (aza)phthalocyanine hydrophobic cores by introducing multiple polyethylene glycol (PEG) moieties with controlled orientations of their (non)peripheral positions is an innovative approach to fabricating water‐soluble macrocyclic materials. Although many water‐soluble PEGylated macrocycles have been produced in this way, the ability to generate substances with PEG tails oriented outward from the macrocyclic plane in order to obtain non‐aggregated, water soluble forms remains a challenge. In this study, we resolved this issue by developing a methods for the synthesis of four new dual directional PEG containing Zn(II)/Mg(II) amphiphiles (ZnPc−PEG, MgPc−PEG, ZnAzaPc−PEG and MgAzaPc−PEG). In addition, the non‐aggregating behaviour, and photophysical and photochemical properties of these PEG‐complexes were elucidated. [ABSTRACT FROM AUTHOR]

Within this work, we review the metal coordination effect on the photophysics of metal dipyrrinato complexes. Dipyrrinato complexes are promising candidates in the search for alternative transition metal photosensitizers for application in photodynamic therapy (PDT). These complexes can be activated by irradiation with light of a specific wavelength, after which, cytotoxic reactive oxygen species (ROS) are generated. The metal coordination allows for the use of the heavy atom effect, which can enhance the triplet generation necessary for generation of ROS. Additionally, the flexibility of these complexes for metal ions, substitutions and ligands allows the possibility to tune their photophysical properties. A general overview of the mechanism of photodynamic therapy and the properties of the triplet photosensitizers is given, followed by further details of dipyrrinato complexes described in the literature that show relevance as photosensitizers for PDT. In particular, the photophysical properties of Re(I), Ru(II), Rh(III), Ir(III), Zn(II), Pd(II), Pt(II), Ni(II), Cu(II), Ga(III), In(III) and Al(III) dipyrrinato complexes are discussed. The potential for future development in the field of (dipyrrinato)metal complexes is addressed, and several new research topics are suggested throughout this work. We propose that significant advances could be made for heteroleptic bis(dipyrrinato)zinc(II) and homoleptic bis(dipyrrinato)palladium(II) complexes and their application as photosensitizers for PDT. [ABSTRACT FROM AUTHOR]

The development of cancer treatment techniques able to cure tumors located deep in the body is an urgent task for scientists and physicians. One of the most promising methods is X-ray-induced photodynamic therapy (X-PDT), since X-rays have unlimited penetration through tissues. In this work, octahedral iodide tungsten clusters, combining the properties of a scintillator and photosensitizer, are considered as a key component of nanosized polyurethane (pU) particles in the production of materials promising for X-PDT. Cluster-containing pU nanoparticles obtained here demonstrate bright photo- and X-ray-induced emission in both solid and water dispersion, great efficiency in the generation of singlet oxygen, and high sensitivity regarding photoluminescence intensity in relation to oxygen concentration. Additionally, incorporation of the cluster complex into the pU matrix greatly increases its stability against hydrolysis in water and under X-rays. [ABSTRACT FROM AUTHOR]

Here, we investigate the effects introduced in the spectroscopic properties and singlet oxygen generation efficiency of zinc tetra(4-pyridyl) porphyrin (ZnTPyP) when the molecule undergoes outlying decoration with the [RuCl2(PPh3)2(CO)(DMF)] and [RuCl2(dppb)(CO)(DMF)] ruthenium complexes. Our results show that these metallic compounds can significantly affect the electronic and vibronic B- and Q-bands; the excited-state deactivation processes; and the singlet oxygen generation quantum yield of the porphyrin, being their influence affected by the ligands present in the ruthenium complexes. [ABSTRACT FROM AUTHOR]

DNA phase separation participates in chromatin packing for the modulation of gene transcription, but the induction of DNA phase separation in living cells for disease treatment faces huge challenges. Herein, we construct a Ru(II)-polypyridyl-loaded upconversion nanoplatform (denoted as UCSNs-R) to achieve the manipulation of DNA phase separation and production of abundant singlet oxygen ( 1 O 2 ) for efficient treatment of gliomas. The utilization of the UCSN not only facilitates high loading of Ru(II)-polypyridyl complexes (RuC) but also promotes the conversion of near-infrared (NIR) laser to ultraviolet light for efficient 1 O 2 generation. The released RuC exhibit DNA "light-switch" behavior and high DNA binding affinity that induce phase separation of DNA in living cells, thus resulting in DNA damage and suppressing tumor-cell growth. In vivo investigation demonstrates the high capability of UCSNs-R in inhibiting tumor proliferation under NIR laser illumination. This work represents a paradigm for designing a DNA phase separation nanoinducer through integration of the UCSN with Ru(II)-polypyridyl-based complexes for efficient therapy of gliomas.

A novel asymmetric Zn (II) phthalocyanine (Pcs) (5) peripherally substituted with one cyclotriphosphazene ring and six tert-butylphenoxy groups was synthesized and fully characterized by elemental analysis, mass, 1H, 13C, 31P NMR, and FT-IR spectroscopies. Photophysical and photochemical properties of 5 (ground state absorption, fluorescence emission, fluorescence lifetime, fluorescence quantum yield, and singlet oxygen generation) were investigated in DMSO and THF. The determined singlet oxygen quantum yields of compound 5 in DMSO and THF were 0.62 and 0.52, respectively. These singlet oxygen quantum yields are very near the singlet oxygen quantum yield of unsubstituted Zn(II) Pcs used as the reference compound. This new Zn(II) Pcs may be a promising candidate for photodynamic therapy (PDT) with its photophysical and photochemical properties. [ABSTRACT FROM AUTHOR]

The study's aim was to synthesize new unsymmetrical sulfanyl zinc(II) porphyrazines and subject them to physicochemical and electrochemical characterization and also an initial acute toxicity assessment. The procedure was initiated from a commercially available dimercaptomaleonitrile disodium salt and o-phthalonitrile using Linstead's macrocyclization reaction conditions, which led to magnesium(II) tribenzoporphyrazine with 4-(3,5-dibutoxycarbonylphenoxy)butylthio substituents. The obtained macrocycle was demetallated with trifluoroacetic acid and subsequently remetallated with zinc(II) acetate toward the zinc(II) porphyrazine derivative. The zinc(II) tribenzoporphyrazine with 4-(3,5-dibutoxycarbonylphenoxy)butylthio substituents was then subjected to the reduction reaction with LiAlH4, yielding zinc(II) tribenzoporphyrazine with 4-[3,5-di(hydroxymethyl)phenoxy]butylthio substituents. The new zinc(II) tribenzoporphyrazines were characterized by UV-Vis spectroscopy, various NMR techniques (1HNMR, 13CNMR, 1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC), and mass spectrometry. In the UV-Vis spectra, both macrocycles revealed characteristic Soret and Q-bands, whose positions were dependent on the solvent used for the measurements. Zinc(II) tribenzoporphyrazines were studied using electrochemical and photochemical methods, including the singlet oxygen generation assessment. Both zinc(II) porphyrazines revealed high singlet oxygen generation quantum yield values of up to 0.59 in DMSO, which indicates their potential photosensitizing potential for photodynamic therapy. In addition, new derivatives were subjected to a Microtox® bioluminescence assay. [ABSTRACT FROM AUTHOR]

[Display omitted] • Luminescent dipyrrinato complexes of Re and Ir with different types of co-ligands are discussed. • Re and Ir complexes are known as triplet sensitizers and they can generate significant amount of singlet oxygen. • Their synthetic methodologies, structures and optical properties are discussed in detail. • Their potential as cellular imaging agents or as photosensitizers for anticancer applications is discussed. Luminescent dipyrrinato complexes of d-block metals are well explored in literature for diverse applications in materials as well as in biology. They offer exceptional fine tuning of their electrochemical and optical properties with the variety of substitutions on the dipyrrin core. The development of mixed ligand type dipyrrinato complexes with heavy metals like: Ru, Os, Pd, Pt, Re, Ir are of great interest in biomedical applications due to significant ROS (Reactive Oxygen Species) generation, anti-microbial and anti-cancer applications. Such dipyrrinato complexes display bright triplet emission in the visible to red region due to heavy atom effect. This review is focused on the synthesis of luminescent dipyrrinato complexes of Re(I) and Ir(III) with different types of co-ligands around the metal center. The overviewed complexes are subcategorized further on the basis of metal and substitutions on the dipyrrin C-5 position or around the metal center. Re and Ir complexes of subporphyrin, N- confused porphyrin, sapphyrin, rubyrin and N- fused porphyrins have also been included. Their absorption and emission properties and their ability to work as triplet photosensitizers are discussed. Deliberations are made to understand their potential as cellular imaging agents and/or photosensitizers for ROS generation and phototherapy to treat cancer. [ABSTRACT FROM AUTHOR]

• Ag/MB/R deactivation ratio if higher than Ag/MB and MB/R. • Molecular docking shows that reserpine shows higher affinity toward AcrB than MB. • The size of the Ag NPs has little to no effect on the PDT deactivation rate. • Reserpine does not improve the amount of singlet oxygen generation. • The mechanism of PDT improvement due to reserpine is most likely a result of its blockage of the AcrAB-TolC efflux pump preventing the removal of MB. Efflux pumps are active transporters, which allow the cell to remove toxic substances from within the cell including antibiotics and photosensitizer complexes. Efflux pump inhibitors (EPIs), chemicals that prevent the passage of molecules through efflux pumps, play a crucial role in antimicrobial effectiveness against pathogen. In this work, we studied the effect of EPI, namely, reserpine, on photodeactivation rate of pathogens when used with Ag NPs and methylene blue (MB). Our results show that using reserpine led to a higher deactivation rate than Ag NPs and MB alone. The mechanism of this observation was investigated with singlet oxygen generation amount. Additionally, different sizes of Ag NPs were tested with reserpine. Molecular docking calculation shows that reserpine had higher affinity toward AcrB than MB. The improvement in bacterial deactivation rate is attributed to blockage of the AcrAB-TolC efflux pump preventing the removal of MB rather than enhanced singlet oxygen production. These results suggest that using reserpine with nanoparticles and photosynthesize is a promising approach in photodynamic therapy. [ABSTRACT FROM AUTHOR]

Cancer and drug-resistant superinfections are common and serious problems afflicting millions worldwide. Photodynamic therapy (PDT) is a successful and clinically approved modality used for the management of many neoplastic and nonmalignant diseases. The combination of the light-activated molecules, so-called photosensitizers (PSs), with an appropriate carrier, is proved to enhance PDT efficacy both in vitro and in vivo. In this paper, we focus on the solvation of several potential chlorin PSs in the 1-octanol/phosphate saline buffer biphasic system, their interaction with non-ionic surfactant Tween 80 and photoinactivation of cancer cells. The chlorin conjugates containing d-galactose and l-arginine fragments are found to have a much stronger affinity towards a lipid-like environment compared to ionic chlorins and form molecular complexes with Tween 80 micelles in water with two modes of binding. The charged macrocyclic PSs are located in the periphery of surfactant micelles near hydrophilic head groups, whereas the d-galactose and l-arginine conjugates are deeper incorporated into the micelle structure occupying positions around the first carbon atoms of the hydrophobic surfactant residue. Our results indicate that both PSs have a pronounced affinity toward the lipid-like environment, leading to their preferential binding to low-density lipoproteins. This and the conjugation of chlorin e6 with the tumor-targeting molecules are found to enhance their accumulation in cancer cells and PDT efficacy. [ABSTRACT FROM AUTHOR]

Integrating multiple photosensitive properties into an "all-in-one" photosensitizer (PS) shows great promise for the treatment of cancers owing to synergistic effect among them. However, the development of such PSs, especially those that need a single laser source, remains a challenge. Herein, we report an orchestration of electron donors and acceptors in a propeller-like pentad, PBI-4Cz, where four carbazole (Cz) units are covalently linked to the ortho-positions of the perylene bisimide (PBI) core. Strong intramolecular donor-acceptor interaction significantly quenches the luminescence and largely extends the absorption spectra to near-infrared region. Excited-state dynamics investigated via femto- and nano-second transient absorption spectroscopy revealed exclusive charge separation of the PBI-4Cz within initial 0.5 ps when photoexcited regardless of which intermediate is involved. Energy dissipation of the resulting charge-separated state (PBI•−-4Cz•−) is subjected to the toggle between intersystem-crossing toward excited triplet states and charge recombination toward ground states. Relative importance of the two pathways can be tuned by micro-environmental polarity, which endows PBI-4Cz remarkable performances of singlet-oxygen generation (>90.0%) in toluene and photothermal conversion (∼28.6%) in DMSO. Harnessing intrinsic photostability and excited-state processes of heavy-atom-free PBI derivatives not only holds a promise for multifunctional phototheranostics, but also provides a prototype for designing high-performance PSs with tunable photoconversion pathways. [ABSTRACT FROM AUTHOR]

The photochemical and photophysical properties of a Re(I) tricarbonyl complex, ClRe(CO)3(nHo)2, where nHo = 9H-pyrido[3,4-b] indole (norharmane), were investigated in solution phase by a combination of steady state emission spectroscopy, laser flash photolysis (LFP) and pulse radiolysis (PR) techniques. These results allowed us to identify and study the reactivity of the β-carboline (nHo) Rhenium(I) complex main excited states. The absorption spectrum as well as the steady-state and time-resolved luminescence of the complex exhibits a marked dependence with the solvent properties. These experimentally observed results were corroborated by quantum chemical calculations, TD-DFT. The most important electronic transitions present in the spectrum in all solvents are MLLCTRe(CO)3→nHo1, nHo2 along with a mixture of ILnHo and LLCTCl→nHo transitions. The relationship between the dipole moment and the polarity of the solvent was rationalized in terms of the electron density inside and outside the complex. While the luminescence of the complex is mainly attributed to the emitting 1ILnHo state, in LFP experiments a MLCT excited state was also detected. The species generated in either reductive or oxidative conditions in LFP experiments were compared with those obtained in PR. Also, the quenching rate constant (kq) of the excited state with MV+2 was calculated. The excited state of the complex can efficiently generate singlet oxygen in acetonitrile yielding a ΦΔ = 0.25 ± 0.02. Optoacoustic measurements showed that, after photonic excitation, almost all the absorbed energy by the complex is released to the medium as prompt heat. The investigated photophysical and photochemical properties of ClRe(CO)3(nHo)2 are of significant importance in relation to the use of this β-carboline Rhenium(I) complex in several biomedical fields, such as photodynamic therapy and photoactivated chemotherapy as well as new alternative therapies such as regional hyperthermia.

The development of cancer treatment techniques able to cure tumors located deep in the body is an urgent task for scientists and physicians. One of the most promising methods is X-ray-induced photodynamic therapy (X-PDT), since X-rays have unlimited penetration through tissues. In this work, octahedral iodide tungsten clusters, combining the properties of a scintillator and photosensitizer, are considered as a key component of nanosized polyurethane (pU) particles in the production of materials promising for X-PDT. Cluster-containing pU nanoparticles obtained here demonstrate bright photo- and X-ray-induced emission in both solid and water dispersion, great efficiency in the generation of singlet oxygen, and high sensitivity regarding photoluminescence intensity in relation to oxygen concentration. Additionally, incorporation of the cluster complex into the pU matrix greatly increases its stability against hydrolysis in water and under X-rays.

Porphyrinic metal‐organic frameworks (MOFs) are promising photosensitizers due to the lack of self‐aggregation of porphyrin in aqueous solution. However, how the topology of porphyrinic MOFs affects the generation of singlet oxygen (1O2) is unclear. Here, the effect of the topology of porphyrinic MOFs on their photodynamic performance is reported. Four porphyrinic zirconium MOFs (MOF‐525, MOF‐545, PCN‐223 and PCN‐224 with different topologies: ftw, csq, shp and she, respectively) were selected to study the influence of topology on the photodynamic antibacterial performance. The 1O2 generation and the photodynamic antibacterial performance followed an decreasing order of MOF‐545>MOF‐525>PCN‐224>PCN‐223. The results reveal that the pore size, the distance between porphyrin, and the number of porphyrin per Zr6O8 cluster in MOFs greatly affected 1O2 generation. This work provides guidance for designing new MOFs for efficient photodynamic sterilization. [ABSTRACT FROM AUTHOR]

A major problem with the use of peripherally unsubstituted metal-free phthalocyanine (H 2 Pc) and the corresponding metal complexes with Co(II), Zn(II) and Ni(II) as catalysts or photocatalyts is their extensive aggregation in most organic solvents and water. In order to overcome the aggregation of phthalocyanine compounds, metal-free phthalocyanine (H 2 Pc) and the corresponding metal complexes with Co(II), Zn(II) and Ni(II) dispersed on porous nano-structured amberlyst 15 (nanoAmbSO 3 H) were synthesized and used as efficient photosensitizers in the aerobic oxidation of methyl phenyl sulfide under aqueous and non-aqueous conditions. The polymer supported photosensitizers, H 2 Pc@nanoAmbSO 3 H, ZnPc@nanoAmbSO 3 H, CoPc@nanoAmbSO 3 H and NiPc@nanoAmbSO 3 H , were characterized by diffuse reflectance UV–Vis spectroscopy (DRS), FESEM/EDX-Mapping, AFM, IR, TGA and BET. The singlet oxygen quantum yield (φ Δ) of the photosensitizers was determined through the oxidation of 1,3-diphenylisobenzofuran as a specific quencher of singlet oxygen. Solution UV–vis and DRS studies showed the lack of metal leaching from the metal complexes but significant red shift of the absorption bands upon exposure to sulfuric acid and the acidic conditions caused by the –SO 3 H groups of the strongly acidic polymer. A particle size less than 50 nm was determined for the almost spherical nanocomposites. In contrast to the metallophthalocyanines, the incorporation of H 2 Pc into the polymer structure led to a remarkable decrease in the thermal stability of the polymer. The immobilized photosensitizers were much more efficient than the non-immobilized counterparts (CoPc, ZnPc, NiPc and H 2 Pc), although no catalyst degradation was observed for the both series. In the present study, the interaction of the –SO 3 H groups of a nanostructured mesoporous polymer with phthalocyanines and its metal complexes was used to design new photosensitizers with red shifted absorption bands and high stability under oxidative conditions. Also, the insoluble photosensitizers, effectively dispersed on the polymer support showed remarkably increased photocatalytic activity relative to that of their non-immobilized counterparts. [Display omitted] • Phthalocyanine-amberlyst 15 nanocomposites as new photosensitizers. • Dispersion of insoluble photosensitizers into a nanostructured polymer. • Significantly enhanced photocatalytic activity of phthalocyanines and its metal complexes. • Comparable photocatalytic activity of the free base and metal complexes. • High dissociation stability of metallophthalocyanines on a highly acidic polymer. [ABSTRACT FROM AUTHOR]

[Display omitted] • The new bis(β-Br-BODIPY) 1 dimer were synthesized and characterized; • Dye 1 exhibits efficient fluorescence and 1O 2 generation in nonpolar solvents; • 1@ZIF-8 nanoscale delivery systems with pH-controled dye release were obtained. • Water-soluble nanoparticles of 1 were achieved by using Pluronic® F127 micelles. • The resulting bis(β-Br-BODIPY) delivery systems are promising for PDT and APDT. The design of biocompatible photosensitizers with an optimal combination of intense fluorescence and generation of singlet oxygen is a complex and urgent task. The article presents the results of synthesizing, analyzing the structure, and examining the chromophoric, fluorescent, and generation characteristics of new dimeric bis(β-Br-BODIPY) (1), as well as the features of its encapsulation in ZIF-8 zeolite framework and solubilization by Pluronic® F127 micelles. The photophysical characteristics of brominated dimer 1 were analyzed in comparison with non-halogenated dimers bis(β-H-BODIPY) (2), bis(β-CH 3 -BODIPY) (3), as well as dibromo-substituted mononuclear analogue β,β-dibromo-BODIPY (4). Dye 1 exhibits efficient fluorescence (from 53 to 72%) and 1O 2 generation (from 19 to 42%) in solutions of nonpolar and weakly polar solvents. Dimerization leads to a high sensitivity of the fluorescence and generation characteristics of the halogenated dimer 1 to the solvent. The advantage of dimer 1 is a significantly lower tendency to aggregate compared to monomer 4. The conditions for the encapsulation of dye 1 in ZIF-8 nanoparticles and Pluronic® F127 micelles were determined and their structural and spectral characteristics were analyzed. [ABSTRACT FROM AUTHOR]

Teeth whitening is one of the most sought-after procedures in aesthetic dentistry. Discolorites that are difficult to whiten, caused by dentin changes or enamel defects, can be eliminated by oxidizing the chromogens with chemical agents that penetrate to the enamel and dentin. In recent years, the method of photodynamic bleaching (PDB) is considered to be minimally invasive. It does not use hydrogen peroxide that leads to increased sensitivity of teeth, and is relatively effective over time. A convenient solution for PDB would be to use chlorin e6 as a photosensitizer, which has a high quantum yield of singlet oxygen generation, low phototoxicity, rapid elimination, on the one hand, and photobleaching capability, on the other. This paper presents quantitative data on the study of the effectiveness of PDB with chlorine e6: color change for 100 teeth after the procedure, chlorine e6 penetration into the tooth tissues, evaluation of the interstitial efficiency of the generation of singlet oxygen and photobleaching of chlorine e6 during laser exposure. It has been statistically established that for one PDB procedure, the tooth color saturation (C) varies on average by 0.5 tones on the VITA scale, and the lightness of color (L) in some cases increases by more than 10 units.

The study’s aim was to synthesize new unsymmetrical sulfanyl zinc(II) porphyrazines and subject them to physicochemical and electrochemical characterization and also an initial acute toxicity assessment. The procedure was initiated from a commercially available dimercaptomaleonitrile disodium salt and o-phthalonitrile using Linstead’s macrocyclization reaction conditions, which led to magnesium(II) tribenzoporphyrazine with 4-(3,5-dibutoxycarbonylphenoxy)butylthio substituents. The obtained macrocycle was demetallated with trifluoroacetic acid and subsequently remetallated with zinc(II) acetate toward the zinc(II) porphyrazine derivative. The zinc(II) tribenzoporphyrazine with 4-(3,5-dibutoxycarbonylphenoxy)butylthio substituents was then subjected to the reduction reaction with LiAlH4, yielding zinc(II) tribenzoporphyrazine with 4-[3,5-di(hydroxymethyl)phenoxy]butylthio substituents. The new zinc(II) tribenzoporphyrazines were characterized by UV-Vis spectroscopy, various NMR techniques (1HNMR, 13CNMR, 1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC), and mass spectrometry. In the UV-Vis spectra, both macrocycles revealed characteristic Soret and Q-bands, whose positions were dependent on the solvent used for the measurements. Zinc(II) tribenzoporphyrazines were studied using electrochemical and photochemical methods, including the singlet oxygen generation assessment. Both zinc(II) porphyrazines revealed high singlet oxygen generation quantum yield values of up to 0.59 in DMSO, which indicates their potential photosensitizing potential for photodynamic therapy. In addition, new derivatives were subjected to a Microtox® bioluminescence assay.

Thiohydantoin and quinolone derivatives have attracted researchers’ attention because of a broad spectrum of their medical applications. The aim of our research was to synthesize and analyze the antimicrobial properties of novel 2-thiohydantoin and 2-quinolone derivatives. For this purpose, two series of hybrid compounds were synthesized. Both series consisted of 2-thiohydantoin core and 2-quinolone derivative ring, however one of them was enriched with an acetic acid group at N3 atom in 2-thiohydantoin core. Antibacterial properties of these compounds were examined against bacteria: Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The antimicrobial assay was carried out using a serial dilution method to obtain the MIC. The influence of blue light irradiation on the tested compounds was investigated. The relative yield of singlet oxygen (1O2*, 1Δg) generation upon excitation with 420 nm was determined by a comparative method, employing perinaphthenone (PN) as a standard. Antimicrobial properties were also investigated after blue light irradiation of the suspensions of the hybrids and bacteria placed in microtitrate plates. Preliminary results confirmed that some of the hybrid compounds showed bacteriostatic activity to the reference Gram-positive bacterial strains and a few of them were bacteriostatic towards Gram-negative bacteria, as well. Blue light activation enhanced bacteriostatic effect of the tested compounds.

Sandhya Clement,1,2,* Wenjie Chen,1,* Wei Deng,1,2 Ewa M Goldys1,2 1Australian Research Council Centre of Excellence for Nanoscale BioPhotonics (CNBP), Department of Physics and Astronomy, Macquarie University, Sydney, NSW, Australia; 2The Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia *These authors contributed equally to this work Introduction: The depth limitation of conventional photodynamic therapy (PDT) with visible electromagnetic radiation represents a challenge for the treatment of deep-seated tumors. Materials and methods: To overcome this issue, we developed an X-ray-induced PDT system where poly(lactide-co-glycolide) (PLGA) polymeric nanoparticles (NPs) incorporating a photosensitizer (PS), verteporfin (VP), were triggered by 6 MeV X-ray radiation to generate cytotoxic singlet oxygen. The X-ray radiation used in this study allows this system to breakthrough the PDT depth barrier due to excellent penetration of 6 MeV X-ray radiation through biological tissue. In addition, the conjugation of our NPs with folic acid moieties enables specific targeting of HCT116 cancer cells that overexpress the folate receptors. We carried out physiochemical characterization of PLGA NPs, such as size distribution, zeta potential, morphology and in vitro release of VP. Cellular uptake activity and cell-killing effect of these NPs were also evaluated. Results and discussion: Our results indicate that our nanoconstructs triggered by 6 MeV X-ray radiation yield enhanced PDT efficacy compared with the radiation alone. We attributed the X-ray-induced singlet oxygen generation from the PS, VP, to photoexcitation by Cherenkov radiation and/or reactive oxygen species generation facilitated by energetic secondary electrons produced in the tissue. Conclusion: The cytotoxic effect caused by VP offers the possibility of enhancing the radiation therapy commonly prescribed for the treatment of cancer by simultaneous PDT. Keywords: PLGA nanoparticles, verteporfin, singlet oxygen generation, photodynamic therapy, X-ray PDT, folic acid targeting

New conjugates of fluorophore based on 3,4-dimethoxy-4-styryl-1,8-naphthalimide and photosensitizer bacteriochlorin e differing in the nature of spacer fragments were synthesized and their spectral-luminescent properties were studied. The conjugates efficiently generate singlet oxygen in solution, however, the emission of the naphthalimide fragment of the conjugates is quenched to varying degrees as a result of the photoexcitation energy transfer to bacteriochlorin. [ABSTRACT FROM AUTHOR]

The G-quadruplex-forming sequence within the KRAS proto-oncogene P1 promoter is a promising target for anticancer therapy. Porphyrin derivatives are among the most rewarding G-quadruplex binders. They can also behave as photosensitizers. Three water-soluble, positively charged porphyrin-like compounds were synthesized and tested for their interaction with the KRAS G-quadruplex by circular dichroism, fluorescence, and molecular docking calculations. For a comparison of ligands binding affinity and selectivity, TMPyP4 was taken as a reference. One out of the three tested compounds proved biological activity and selectivity for G-quadruplex over duplex DNA. It also showed to discriminate between different G-quadruplex topologies, with a preference for the parallel over antiparallel conformation. Molecular docking studies suggested a preferential binding to the 3′-end of the KRAS G-quadruplex driven through π-π stacking interactions. Biological assays also revealed a good photodynamic-induced cytotoxicity on HeLa cells. The reported results show that these porphyrin-like compounds could actually give the basis for the development of G-quadruplex ligands with effective photodynamic-induced cytotoxicity on cancer cells. The possibility of obtaining photosensitizers with improved physico-chemical features and able to selectively target G-quadruplexes is a very interesting perspective to develop new therapeutic agents. [ABSTRACT FROM AUTHOR]

A series of porous organic polymers based on a singlet oxygen generating oxoporphyinogen (‘OxP’) has been successfully prepared from a pseudotetrahedral OxP-tetraamine precursor (OxP(4-NH2Bn)4) by its reaction with tetracarboxylic acid dianhydrides under suitable conditions. Of the compounds studied, those containing naphthalene (OxP-N) and perylene (OxP-P) spacers, respectively, have large surface areas (~530 m2 g−1). On the other hand, the derivative with a simple benzene spacer (OxP-B) exhibits the best1O2 generating capability. Although the starting OxP-tetraamine precursor is a poor1O2 generator, its incorporation into OxP POPs leads to a significant enhancement of1O2 productivity, which is largely due to the transformation of – NH2 groups to electron-withdrawing diimides. Overall1O2 production efficacy of OxP-POPs under irradiation by visible light is significantly improved over the common reference material PCN-222. All the materials OxP-B, OxP-N and OxP-P promote oxidation of thioanisole involving conversion of ambient triplet state oxygen to singlet oxygen under visible light irradiation and its reaction with the sulfide. Although the reaction rate of the oxidation promoted by OxP POPs is generally lower than for conventional materials (such as PCN-222) or previously studied OxP derivatives, undesired overoxidation of the substrate to methyl phenyl sulfone is suppressed. For organic sulfides, selectivity of oxidation is especially important for detoxification of mustard gas (bis(2-chloroethyl)sulfide) or similarly toxic compounds since controlled oxidation leads to the low toxicity bis(2-chloroethyl)sulfoxide while overoxidation leads to intoxification (since bis(2-chloroethyl)sulfone presents greater toxicity to humans than the sulfide substrate). Therefore, OxP POPs capable of promoting selective oxidation of sulfides to sulfoxides have excellent potential to be used as mild and selective detoxification agents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni 2 P/BP is formed by doping Ni onto the surface of black phosphorus (BP) by a one-pot method successfully. • The as prepared Ni 2 P/BP shows a better ambient stability and more efficient interfacial charge separation than that of BP under NIR light irradiation. • The Ni 2 P/BP can activate oxygen to generate singlet oxygen through Russell Mechanism for water remediation and disinfection under NIR irradiation. Black phosphorus (BP) shows great potential applications in photoelectric conversion and photocatalysis, but its applications are limited by its disadvantages such as poor ambient stability and rapid carrier recombination under photoirradiation. In this work, it was surprisingly found that the in-situ generation of Ni 2 P onto the surface of BP leaded to a significant improvement in both ambient stability and photocatalytic singlet oxygen (1O 2) generation under NIR irradiation. Because of the transfer of electrons from Ni to BP via Ni-P bonds, the Ni 2 P/BP showed better charge separation efficiency and ambient stability in NIR photoelectric conversion. Moreover, the Ni 2 P/BP was able to generate 1O 2 for NIR photocatalysis through Russell Mechanism. Meanwhile, norfloxacin and E. coli could also be removed by Ni 2 P/BP under NIR irradiation, which further shows the ability to generate 1O 2 for practical utilization. This work provides a novel insight into the passivation of BP by hetero-atoms doping and a new strategy for green NIR photocatalytic water remediation. [ABSTRACT FROM AUTHOR]

Zofia Kautzka, Sandhya Clement, Ewa M Goldys, Wei Deng Centre of Excellence for Nanoscale BioPhotonics, Macquarie University, North Ryde, Sydney, NSW, Australia Abstract: We developed light-triggered liposomes incorporating 3–5 nm hydrophobic gold nanoparticles and Rose Bengal (RB), a well-known photosensitizer used for photodynamic therapy. Singlet oxygen generated by these liposomes with 532 nm light illumination was characterized for varying the molar ratio of lipids and gold nanoparticles while keeping the amount of RB constant. Gold nanoparticles were found to enhance the singlet oxygen generation rate, with a maximum enhancement factor of 1.75 obtained for the molar ratio of hydrogenated soy l-α-phosphatidylcholine:1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(hexanoylamine):gold of 57:5:17 compared with liposomes loaded with RB alone. The experimental results could be explained by the local electric field enhancement caused by gold nanoparticles. We further assessed cellular cytotoxicity of gold-loaded liposomes by encapsulating an antitumor drug, doxorubicin (Dox); such Dox-loaded liposomes were applied to human colorectal cancer cells (HCT116) and exposed to light. Gold-loaded liposomes containing RB and Dox where Dox release was triggered by light were found to exhibit higher cytotoxicity compared with the liposomes loaded with RB and Dox alone. Our results indicate that gold-loaded liposomes incorporating photosensitizers may serve as improved agents in photodynamic therapy and chemotherapy. Keywords: liposomes, Rose Bengal, gold nanoparticles, singlet oxygen generation, photodynamic therapy

Porphyrins, especially the 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin (TMPyP), are well-accepted as photosensitizers due to strong absorption from visible to near-infrared region, good singlet oxygen quantum yields as well as chemical versatility, all of which can be further modulated through planned supramolecular strategies. In this study, we report the construction of supramolecular nanorods of TMPyP dye/drug with captisol [sulfobutylether-β-cyclodextrin (SBE7βCD)] macrocycle through host-guest interaction. The availability of four cationic N-methylpyridyl groups favors multiple binding interaction with the captisol host, building an extended supramolecular assembly of captisol and TMPyP. In addition to the spectroscopic characterizations for the assembly formation, the same has been pictured in SEM and FM images as nanorods of ~10 μm in length or more. Complexation of TMPyP has brought out beneficial features over the uncomplexed TMPyP dye; enhanced singlet oxygen yield, improved photostability, and better photosensitizing effect, all supportive of efficient photodynamic therapy activity. The Captisol:TMPyP complex displayed enhanced antibacterial activity toward E. coli under white light irradiation as compared to TMPyP alone. Cell viability studies performed in lung carcinoma A549 cells with light irradiation documented increased cytotoxicity of the complex toward the cancer cells whereas reduced dark toxicity is observed toward normal CHO cells. All these synergistic effects of supramolecular nanorods of Captisol-TMPyP complex make the system an effective photosensitizer and a superior antibacterial and antitumor agent.