Combination Of Visible Light Research Articles

Late-stage Functionalization using a Popular Titrating Agent: Aryl-Chlorides and -Fluorides Activation by the Diphenylacetic Acid Dianion.

Aryl-chlorides and -fluorides are common building blocks, but their use in synthesis is limited by the high stability of their Ar-X bonds. The generation of aryl radicals via activation of strong Ar-X bonds is possible through the irradiation of tailor-made organic anions, which become reductants stronger than lithium metal. We report that the combination of visible light with the cheap diphenylacetic acid dianion is an even better tool, showing excellent activity across a variety of complex substrates and providing opportunities for late-stage drug modification. Ar-X bonds are chemoselectively activated in the presence of more easily reducible functions, such as Alk-Cl ones and carbonyl groups. These results pave the way to original synthetic strategies that would be otherwise considered impossible.

Rose bengal photocatalyzed expeditious multicomponent synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones under visible light irradiation

AbstractThe combination of visible light, a renewable and green energy source, and rose bengal, a non‐toxic organic dye as a photoredox catalyst, is an easy and efficient method for synthesizing 3,4‐dihydropyrimidin‐2(1H)‐ones/thiones in EtOH at ambient temperature in very short reaction time. The present work offers simple operation, easy workup, rapid conversion, and excellent product yields, while accommodating a wide range of substrates. Rose bengal‐based photocatalytic approach permits foremost sustainability, which delivers economic and environmental rewards.

Cu:TiO2 nanoparticles prepared by planetary ball mill with enhanced sonophotocatalytic performance with visible light

AbstractIn this research, pure and Cu(II)‐doped TiO2 nanoparticles (NPs) were synthesized via a simple and nontoxic approach to fabricate a nanocatalyst for the oxidative sonophotocatalytic degradation of phenol. TiO2 NPs were prepared using a solvothermal method and doped with Cu(II) by high‐energy planetary ball mill. The as‐synthesized NPs were identified and characterized by X‐ray diffraction, energy‐dispersive X‐ray, and transmission electron microscopy techniques. The doped NPs were used for the first time in pollutant decomposition using phenol as a model pollutant in low‐energy and low‐frequency ultrasound at room temperature and pH = 7 in the presence of visible light. The progress of the pollutant degradation was followed by UV–Vis spectrophotometry. After about 60 min of sonophotocatalytic process (dual irradiation [visible light + ultrasound] in the presence of doped NPs), around 75% of the phenol degraded, with a rate constant of about 0.024 min−1. The sonophotocatalytic process was compared with photocatalysis and sonocatalysis processes conducted in the same conditions. Importantly, the combination of visible light and ultrasound irradiation in a sonophotocatalytic decomposition reaction represented about 58% of the synergy effect, demonstrating a positive synergy between the photocatalytic and sonocatalytic processes. The optimum condition was used to degrade the commercial sample (amoxicillin) with excellent performance. The reusability test represented the excellent stability of doped catalysts within four consecutive runs with less fading in their sonophotocatalytic reaction. This feature proves the reusability potential of the doped catalyst to be used in the commercial and industrial directions. The performance of the doped catalyst was affected severely by the addition of different scavengers, and based on the results, the sonophotocatalytic mechanism was discussed.

Efficient degradation of tetracycline hydrochloride by peroxymonosulfate activated by composite materials FeSe2/Fe3O4 under visible light

The FeSe2/Fe3O4 composite was synthesized by hydrothermal method and used as heterogeneous catalyst for the degradation of TC-HCl. The experimental results showed that under the combination of visible light and PMS, the degradation effect of 50 mg/L 100 mL TC-HCl reached 87.8 % within 60 min at 0.4 g/L FeSe2/Fe3O4 and initial pH value. The radical quenching experiments showed that ·O2−, SO4·− and ·OH were the predominant radicals for the TC-HCl degradation. There was a synergistic action between Fe and Se, which greatly facilitated the activation of PMS and improved the degradation rate of TC-HCl.

Antimicrobial photodynamic treatment (aPDT) as an innovative technology to control spoilage and pathogenic microorganisms in agri-food products: An updated review

Antimicrobial photodynamic treatment (aPDT) is a light-based method developed for the inactivation of microorganisms. With the emergence of antifungal- and antibiotic-resistant microorganisms, aPDT has been suggested as a promising microbial control strategy. The treatment is based on a combination of visible light, a photosensitizer (PS), and molecular oxygen. Illuminating the PS with adequate light in the presence of oxygen will result in the generation of abundant reactive oxygen species (ROS), which further react with multiple targets within microbial cells and eventually cause cell death. The risk of resistance development is low due to the multi-target mode of action of aPDT. The efficiency of aPDT for microbial inactivation on foods can be affected by several factors such as type and characteristics of the PS, light source, food surface geometry, environmental aspects, and microbial characteristics. Although still a concept, the application of aPDT has gained rapid acceptance in many different agri-food products and associated processes, including food production, industrial processing, storage, distribution, and retail. Most of the in vitro aPDT studies have provided evidence of significant antimicrobial effects, including cases in which viability was reduced up to eight orders of magnitude. Strong antimicrobial performance of aPDT was also reported for studies involving variable food matrices, including fruit and vegetables, meat products, and milk. This review provides up-to-date information on advances in the application of aPDT in the agri-food sector, including suitable photosensitizers, sources of light, microbial inactivation efficiency, the role of food matrix composition, potentiation effects, inactivation mechanisms, and potential or prospective applications in the food industry and in other areas of agriculture. Even though the field of aPDT is advancing rapidly, future research should aim at some topics, including (1) the complete analysis of the effects of the treatment on food matrices, (2) the inactivation of currently-neglected food spoilage microorganisms, and (3) comprehensive field evaluation of aPDT for the control of plant diseases, all of which are necessary in order for the treatment to find widespread use in the agri-food sector. • aPDT is efficient at inactivating food spoilage microorganisms. • Chlorophyllin and curcumin are the natural PS of choice. • Fruit, vegetables, and meat are the most studied food matrices. • Future studies with thermophilic food spoilage organisms are needed. • Thorough food matrix analysis after treatment is still lacking.

Enhancement of TiO2 activity under visible light by N,S codoping for Pb(II) removal from water

This paper deals with a systematic study on the co-doping N,S on TiO2 photocatalyst to improve its activity under visible light on the removal of Pb(II) from the aqueous media. The co-doping TiO2 by N,S atoms was conducted in an autoclave by one-step hydrothermal of TiO2 mixed with nitric and sulfuric acids as the sources of N and S, respectively. The mole ratio of TiO2:nitric acid:sulfuric acid was varied as 1:1:0.5, 1:1:1, and 1:1:1.5 to find the best ratio toward the activity. The co-doped photocatalysts obtained were characterized by specular reflectance UV/Vis (SRUV), X-ray diffraction (XRD), and fourier transform infrared (FTIR) instruments. A batch experiment was carried out for oxidation of Pb(II), driven by a combination of visible light and TiO2-N,S photocatalyst. The research results attribute that co-doping N,S into TiO2 has remarkably narrowed the gap in the TiO2 structure, emerging in the visible region. It was also proven that the co-doped in TiO2 can considerably enhance its activity in the removal of Pb(II) under visible light, and the highest activity was owned by TiO2-N,S (1:1:1). Furthermore, the most effective removal of Pb(II) 10 mg/L (98%) could be reached by employing 500 mg L-1 of the TiO2-N,S (1:1:1) dose, 45 min of the time, and the solution pH at 7. The Pb(II) removed is due to the photo-oxidation induced by OH radicals to form the handleable PbO2.

Highly efficient removal of tetracycline hydrochloride under neutral conditions by visible photo-Fenton process using novel MnFe2O4/diatomite composite

A simple solvothermal method was used to prepare poly-porous MnFe2O4/diatomite (MFD) with excellent catalytic performance. The characteristics of the prepared catalysts were examined by XRD, SEM, BET, XPS, UV-DRS, PL and NH3-TPD. BET analysis indicated that introduction of diatomite could increase the specific surface and porosity of the MFD. NH3-TPD studies clearly revealed that loading onto diatomite increased the availability of acid sites and surface hydroxyl groups in the composite materials. Under the combination of visible light and H2O2, the degradation effect of 80 mg/L 100 mL tetracycline hydrochloride (TC-HCl) reached 96.7% within 60 min at 0.1 g/L MFD and initial pH value, according to the experimental results. The proposed heterogeneous photo-Fenton system with MnFe2O4/diatomite showed an extremely wide pH range of 3–11 for TC-HCl degradation. At pH = 7, 91.8% of the TC-HCl (80 mg/L 100 mL) could be degraded within 60 min. In addition, the removal rate remained close to 90% after 60 min of irradiation at pH = 9 and 11. Free radical capture experiment showed that superoxide radicals (•O2−) and holes (h+) play a crucial role in the removal of TC-HCl. Moreover, the synergistic activation of H2O2 by Fe and Mn was confirmed to promote the degradation, leading to higher TC-HCl removal efficiency.

Decarboxylative Alkyl Coupling Promoted by NADH and Blue Light.

Photoexcited dihydronicotinamides like NADH and analogues have been found to generate alkyl radicals upon reductive decarboxylation of redox-active esters without auxiliary photocatalysts. This principle allowed aliphatic photocoupling between redox-active carboxylate derivatives and electron-poor olefins, displaying surprising water and air-tolerance and unusually high coupling rates in dilute conditions. The orthogonality of the reaction in the presence of other carboxylic acids and its utility in the functionalization of DNA is presented, notably using visible light in combination with NADH, the ubiquitous reductant of life.

Orthogonal Syntheses of 3.2.0 Bicycles from Enallenes Promoted by Visible Light.

Enallenes can be readily converted into two families of 3.2.0 (hetero)bicycles with high diastereoselectivities through the combination of visible light with a suitable Ir(III) complex (1 mol %). Two complementary pathways, namely, a photocycloaddition versus a radical chain, can then take place. Both manifolds grant complete regiocontrol of the allene difunctionalization. This is accompanied by an original 1,3-group shift using sulfonyl allenamides that deliver a congested tetrasubstituted headbridging carbon in the corresponding product.

3135 – VISIBLE VIOLET-BLUE LIGHT FOR PATHOGEN REDUCTION OF BLOOD PLASMA: ASSESSMENT OF BROAD SPECTRUM ANTIBACTERIAL EFFICACY AND PRELIMINARY COMPATIBILITY STUDIES

Bacterial contamination of blood products is a major concern in transfusion medicine. Continued efforts to improve blood safety include the use of pathogen reduction technologies (PRTs), which for plasma includes solvent-detergent treatment, or the use of ultraviolet or visible light in combination with photosensitizers. Non-ionizing violet-blue light, in the region of 405nm, has recently demonstrated potential for in situ treatment of ex vivo stored plasma and platelet products, without the need for additional photosensitizers. This study investigates the broad spectrum antibacterial efficacy of 405 nm light for pathogen reduction of plasma samples. Human plasma was seeded with a range of bacteria implicated in transfusion transmitted infections: Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae and Yersinia enterocolitica. The organisms were seeded at 10², 10⁵ and 10⁷ CFU mL⁻¹ densities and exposed to a 405 nm light dose of 360 Jcm⁻² (1-hr at 100 mWcm⁻²). Broad spectrum antibacterial efficacy was observed, with significant bacterial inactivation achieved for all species (P≤0.05). 98.9 – 100 % inactivation was achieved across all seeding densities for all organisms except E. coli, which achieved 95.1 – 100.0 % inactivation. Preliminary protein analysis, conducted using SDS-PAGE, assessed the compatibility of an effective antibacterial dose with plasma proteins. Protein stability tests provide the first evidence for the compatibility of 405 nm light for the decontamination of plasma, with no visible signs of protein degradation detected for doses ≤ 1.8 kJcm⁻². Future studies are required to determine the treatment regime that provides the optimal balance of antibacterial efficacy and product stability.

Visible Light Assisted Selenylative Intramolecular Dearomative Carbo‐Spirocyclisation (IDCS) of Homologated‐Ynones

A visible light assisted dearomative selenylative carbo‐spirocyclisation of aromatic homologated‐ynones has been reported. The ynones deliver selenylative spiro‐cyclohexadienones and spiro‐diepoxides at varied temperatures. The prescribed methodology is photo‐catalyst free and scalable. The combination of visible light, molecular oxygen and the products synthesized delivers a uniqueness to the designed methodology.

Selective C-C Bond Scission of Ketones via Visible-Light-Mediated Cerium Catalysis

Summary Here, we report a general catalytic manifold for the selective C–C bond scission of ketones via the exploitation of the ligand-to-metal charge transfer (LMCT) excitation mode. Through a cooperative utilization of Lewis acid catalysis and LMCT catalysis, the C–C bond of ketones could be selectively and effectively cleaved, enabling the installation of different functionalities at each carbon of the cleaved C–C bond through a sequential and orthogonal manner. This reaction manifold serves as a photocatalytic alternative to the Norrish type I reaction with the combination of visible light and inexpensive cerium salts. Under operationally simple conditions, a wide range of acyclic and cyclic ketones, from simple strained cyclobutanones to complex androsterone with less strained cyclopentanone moiety, could be successfully transformed into versatile chemical building blocks.

Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis.

We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.

Controllable Isomerization of Alkenes by Dual Visible‐Light‐Cobalt Catalysis

AbstractWe report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.

Photosensitized singlet oxygen generation and detection: Recent advances and future perspectives in cancer photodynamic therapy.

Photodynamic therapy (PDT) uses photosensitizers and visible light in combination with molecular oxygen to produce reactive oxygen species (ROS) that kill malignant cells by apoptosis and/or necrosis, shut down the tumor microvasculature and stimulate the host immune system. The excited singlet state of oxygen (1 O2 ) is recognized to be the main cytotoxic ROS generated during PDT for the majority of photosensitizers used clinically and for many investigational new agents, so that maximizing its production within tumor cells and tissues can improve the therapeutic response, and several emerging and novel approaches for this are summarized. Quantitative techniques for 1 O2 production measurement during photosensitization are also of immense importance of value for both preclinical research and future clinical practice. In this review, emerging strategies for enhanced photosensitized 1 O2 generation are introduced, while recent advances in direct detection and imaging of 1 O2 luminescence are summarized. In addition, the correlation between cumulative 1 O2 luminescence and PDT efficiency will be highlighted. Meanwhile, the validation of 1 O2 luminescence dosimetry for PDT application is also considered. This review concludes with a discussion on future demands of 1 O2 luminescence detection for PDT dosimetry, with particular emphasis on clinical translation. Eye-catching color image for graphical abstract.

Flavonols in broccoli (Brassica oleracea L. var. italica) flower buds as affected by postharvest temperature and radiation treatments

The aim of this study was to evaluate the effects of postharvest temperature, light and UV-B irradiation on the flavonol content in broccoli using a multi-level design simulating commercial storage conditions from harvest until consumer purchase. The flavonol content in broccoli flower buds was examined during pre-storage and storage of broccoli heads, representing refrigerated transport with wholesale distribution and retail, respectively. Broccoli heads were pre-stored for four or seven days at 0 or 4°C in the dark and then stored for three days at 10 or 18°C. During storage, the broccoli heads were exposed for 12h per day to three different levels of visible light (13, 19 or 25μmolm−2s−1) or a combination of visible light (19μmolm−2s−1) and UV-B irradiation (0.23Wm−2), or they were stored in the dark. The contents of flavonols (quercetin, kaempferol and isorhamnetin), measured by HPLC as aglycons in flower bud extracts, were not significantly influenced by pre-storage period, pre-storage temperature or storage temperature. However, the interaction between pre-storage period and pre-storage temperature was found significant for flavonol contents during storage, with higher contents observed for broccoli pre-stored shorter (4d) at 4°C and longer (7d) at 0°C. The levels of epidermal flavonols, monitored with non-destructive repeated measurements of the broccoli heads during storage, were observed to increase with the duration of pre-storage and storage. General linear model analysis revealed that the radiation treatments significantly affected both quercetin content and epidermal flavonol levels in broccoli flower buds during storage, with the highest levels observed after a combination of visible light and UV-B irradiation treatment. However, the outcome of that postharvest treatment was influenced by a combination of factors including pre-storage period, pre-storage temperature and storage temperature. For one group of broccoli heads, that were pre-stored for four days at 4°C and exposed to visible light with UV-B irradiation during storage at 10°C, a significant 3.5-fold increase in the level of all flavonols was observed as compared with after pre-storage. The non-destructive measurements demonstrated that accumulation of epidermal flavonols upon UV-B exposure was initiated earlier in broccoli heads when stored at higher temperature (18°C).

Body-Based Gender Recognition Using Images from Visible and Thermal Cameras

Gender information has many useful applications in computer vision systems, such as surveillance systems, counting the number of males and females in a shopping mall, accessing control systems in restricted areas, or any human-computer interaction system. In most previous studies, researchers attempted to recognize gender by using visible light images of the human face or body. However, shadow, illumination, and time of day greatly affect the performance of these methods. To overcome this problem, we propose a new gender recognition method based on the combination of visible light and thermal camera images of the human body. Experimental results, through various kinds of feature extraction and fusion methods, show that our approach is efficient for gender recognition through a comparison of recognition rates with conventional systems.

Glucosinolates in broccoli (Brassica oleracea L. var. italica) as affected by postharvest temperature and radiation treatments

The purpose of the present study was to examine how glucosinolate (GLS) levels in broccoli flower buds are affected by storage time, temperature and radiation treatments in an experiment with multi-level design simulating mapped commercial storage conditions from harvest until consumer purchase. The GLS content in broccoli flower buds was examined during pre-storage and storage of broccoli heads, representing refrigerated transport with wholesale distribution and retail, respectively. The GLS analysis was conducted also for floret stalks of chosen broccoli. Broccoli heads were pre-stored for four or seven days at 0 or 4°C in the dark and then stored for three days at 10 or 18°C. During storage, the broccoli heads were exposed for 12h per day to three different levels of visible light (13, 19 or 25μmolm−2s−1) or a combination of visible light (19μmolm−2s−1) and UV-B irradiation (20kJm−2d−1), or they were stored in the dark. The GLS contents were not changed in broccoli flower buds during pre-storage at low temperatures (0°C or 4°C) for four or seven days. However, general linear model analysis revealed that pre-storage period significantly influenced total GLS, total indolyl and total aliphatic GLS, and all individual GLS levels, except for 4-methoxyglucobrassicin (4-Me-GB) in broccoli flower buds after storage at higher temperatures (10°C or 18°C). Higher levels of these compounds were found in broccoli pre-stored for seven days than in those pre-stored for four days. Storage temperature affected GLS levels in broccoli flower buds significantly. 4-Hydroxyglucobrassicin (4-OH-GB) content was increased after storage at 18°C, while the levels of all other individual GLS, total GLS, as well as total aliphatic and indolyl GLS were higher in flower buds of broccoli after storage at 10°C than at 18°C. The effect of storage temperature on aliphatic GLS in broccoli flower buds depended on pre-storage temperature and it was negligible for broccoli heads pre-stored at 4°C but significant for those pre-stored at 0°C. Radiation treatments applied during storage did not influence total and individual GLS levels in broccoli flower buds. However, the accumulation of aliphatic GLS in broccoli pre-stored for seven days at 0°C and subsequently stored for three days at 10°C under visible light of 25μmolm−2s−1 appeared both in flower buds and floret stalks. Significant increases in indolyl 4-OH-GB and 4-Me-GB contents were observed only in flower buds or floret stalks after storage at 18°C upon exposure to visible light of 25μmolm−2s−1.

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions.

The combination of visible light, photovoltaics, and electrochemistry provides a convenient, inexpensive platform for conducting a wide variety of sustainable oxidation reactions. The approach presented in this article is compatible with both direct and indirect oxidation reactions, avoids the need for a stoichiometric oxidant, and leads to hydrogen gas as the only byproduct from the corresponding reduction reaction.

Synergic phototoxic effect of visible light or Gallium-Arsenide laser in the presence of different photo-sensitizers on Porphyromonas gingivalis and Fusobacterium nucleatum.

Background:According to the development of resistant strains of pathogenic bacteria following treatment with antimicrobial chemotherapeutic agents, alternative approaches such as lethal photosensitization are being used. The aim of this study was to evaluate the effect of visible light and laser beam radiation in conjugation with three different photosensitizers on the survival of two main periodontopathogenic bacteria including Porphyromonas gingivalis and Fusobacterium nucleatum in different exposure periods.Materials and Methods:In this in vitro prospective study, strains of P. gingivalis and F. nucleatum. were exposed to visible light at wavelengths of 440 nm and diode laser light, Gallium-Arsenide, at wavelength of 830 nm in the presence of a photosensitizer (erythrosine, curcuma, or hydrogen peroxide). They were exposed 1-5 min to each light. Each experiment was repeated 3 times for each strain of bacteria. Data were analyzed by two-ways ANOVA and least significant difference post-hoc tests. P < 0.05 was considered as significant. After 4 days the colonies were counted.Results:Viability of P. gingivalis was reduced 10% and 20% subsequent to exposure to visible light and diode laser, respectively. The values were 65% and 75% for F. nucleatum in a period of 5-min, respectively. Exposure to visible light or laser beam in conjugation with the photosensitizers suspension caused significant reduction in the number of P. gingivalis in duration of 5-min, suggesting a synergic phototoxic effect. However, the survival rate of F. nucleatum following the exposure to laser with hydrogen peroxide, erythrosine and rhizome of Curcuma longa (curcumin) after 5-min was 10%, 20% and 90% respectively.Conclusion:Within the limitations of this study, the synergic phototoxic effect of visible light in combination with each of the photosensitizers on P. gingivalis and F. nucleatum. However, the synergic phototoxic effect of laser exposure and hydrogen peroxide and curcumin as photosensitizers on F. nucleatum was not shown.