Journal of Photochemistry and Photobiology最新文献

The photophysical properties and photocatalysis of tris(pentafluorophenyl)borane [B(C₆F₅)₃], known as a strong Lewis acid, were revealed. The excited-state B(C₆F₅)₃ exerts single-electron oxidation capability with an oxidation potential (E_red* = 2.02 V vs SCE) close to those of electronically unbiased toluene derivatives (E_ox = 2.01 to 2.29 V). This property was experimentally proven by the direct observation of the radical cation of the toluene dimer by the transient absorption spectroscopy of a mixture of B(C₆F₅)₃ and toluene. In cooperation with a suitable Brønsted base catalyst, B(C₆F₅)₃ catalytically generated benzylic radicals from toluene derivatives under photoirradiation for subsequent carbon-carbon bond-forming reactions.

Presently we report a second example of a biochemical reaction sensitized remotely by excitons (electronic excited states) efficiently transferred along intermediate filaments (IFs) over macroscopic distances. IFs are excellent conductors of energy in the form of excitons, with the efficiency of ca. 0.53 reported in vitro. Excitons were generated by visible light and propagated along Müller cell (MC) intermediate filaments, about 100 μm long. These experiments used a capillary matrix filled by MC IFs extracted from porcine retina. Excitons induced efficient isomerization of 11-cis- to all-trans-retinal, with the reaction quantum yield φ_cis/trans = 0.347 obtained for 11-cis-retinal concentration of 1.0 × 10⁻³ M (0.284 g/L) using 546 nm light at 6.87 mW/cm² power density. Exciton quantum yield φ_exc at 546 nm was also measured in function of radiation power density, with nonlinearity indicative of biphotonic processes. This is the first case of biphotonic processes occurring at such low light intensities with steady-state illumination. The present results support quantum mechanism of high-contrast vision of vertebrate eyes.

Visible light (VL) has been shown to promote genotoxicity through free radical generation and structural protein degradation. These stressful events promote cellular vulnerability, which manifests clinically as erythema, hyperpigmentation, and photoaging. Having established biologic impacts of VL, development of photoprotection strategies against this part of the solar spectra are warranted. This invited review presents advances in the VL literature and discusses available and potential means of VL photoprotection.

The present work investigates the disinfection of dialysate water used in hemodialysis through the application of bioinspired W/WO₃ electrodes constructed on microbial biofilm from C. parapsilosis by electrochemical anodization. The bioinspired electrode was photoactivated by UV/Vis or visible irradiation, and the photocurrent was found to be at least twice higher than that obtained for nanoporous W/WO₃ electrode in the dialysate water. Under optimized conditions, the photo-electrocatalytic analysis conducted on the bioinspired electrode at E_app = 1.5 V and under UV/Vis irradiation led to complete fungi inactivation (5 min) and up to 70% of total organic carbon removal monitored during cell lysis after 120 min of treatment. The results show the bioinspired electrode maintains the structural print of the fungi and works as fungus recognition material. The proposed electrode is also found to exhibit higher surface area, which improves adsorption of microorganisms, leading to faster and more efficient degradation compared to nanoporous W/WO₃ electrode, with a 30% increase in the degradation of organic matter present in the medium. The findings show that the bioinspired electrode has outstanding advantages when compared with other materials investigated; these advantages include controlled morphology, good reproducibility, higher adsorption on the electrode surface, and higher efficiency in the disinfection of C. parapsilosis, an agent of several cases of contamination in dialysate.

Hole-transport materials (HTMs) contribute an important function in perovskite solar cells (PSCs) for achieving favourable photovoltaic performance with durability. In this work, we designed and synthesized a series of porphyrin based hydrophobic HTMs based on donor-π-donor (D-π-D) tactic in which triphenylimidazole as donor and either free-base porphyrin (H2LD) or metalloporphyrin (Cu, CuLD or Zn, ZnLD) as π-spacer for PSCs. All three HTMs were characterized by a variety of spectroscopic and electrochemical methods. Optical and electrochemical properties propose that the highest occupied molecular orbital (HOMO) energy levels were healthily aligned with the valence band of MAPbI₃ perovskite. Among these HTMs, CuLD exhibited higher hole mobility of 7.39 × 10^-5 cm²V^-1s^-1, when compared to ZnLD 5.77 × 10^-5 cm²V^-1s^-1, and H2LD 2.7 × 10^-5 cm²V^-1s^-1. We fabricated PSCs with these HTMs and among them the CuLD based PSCs showed highest power conversion efficiency of 12.44%. The better PCE for the PSCs fabricated with CuLD could be attributed to the higher conductivity and better hole mobility which could be correlated to the better film formation.

Photoelectrochemical (PEC) water splitting is an emerging technology to store the solar energy in the chemical bonds of molecular hydrogen. Among several photo electrodes used for PEC water splitting, α-Fe₂O₃ is a promising material due to its suitable bandgap, chemical stability, and abundance. Despite these, the position of its conduction band does not allow spontaneous movement of photo-generated electrons to cause the water reduction. This demands the application of a minimum electrical bias of ∼1.5 V vs. SHE to increase the energy of the conduction band such that it will be energetically above the H₂O/H₂ redox level. We show that by utilizing the energy of neutralization, the minimum electrical voltage required for PEC water splitting can be brought down to ∼0.8 V. By employing an OH⁻/H⁺dual-ion configuration. OH⁻/H⁺dual-ion assisted PEC water splitting required only 0.95 V to produce a current density of 10 mA/cm², and for achieving the same rate in a conventional symmetric ion configuration, at least a doubling of the applied electrical bias (∼1.8 V) is required.

Recent publications have confirmed the ability of visible light from sunlight (in the absence of Ultraviolet A or B) to cause free radical formation in human skin, increases in metalloproteinases, induced pigmentation and even erythema from exposures within reasonable exposure periods (e.g. less than 8 h). This raises questions regarding the role of visible light on the formation of skin cancers and even the need for protection against visible light in general. Conducting such studies is a challenge, considering the doses of visible light required for observation of reactions, the difficulty in conducting animal studies with appropriate models in the current regulatory environment, and the lack of funding for basic photobiological research. A review of research from an earlier era in photobiology studies gives us some clues and suggests that there may in fact be detectable influences of visible radiation (for example on skin cancer induction) that warrant new approaches to photoprotection in this era.

We have demonstrated three LY-HTMs for perovskite solar cells in this report. These LY-HTMs embed cyclopentadithiophene (CPT) core that incorporates 2∼4 triphenylamine electron donor units. Designing LY-HTMs with Lewis-basic property of carbonyl or imine, can effectively passivate the defects of insufficiently coordinated Pb²⁺ in the perovskite layer. The LY-HTMs have good thermal stability and enhanced intermolecular interaction, thereby dense packing, due to the sulfur-sulfur interaction in the dithiophene structure. Moreover, the sulfur-sulfur interaction achieves a deeper HOMO energy level that can be well-matched to perovskite solar cells (PSCs). It also improves the charge mobility to enhance Voc and Jsc values. The best performance using LY-1 as a HTM in PSCs exhibited a Jsc of 23.1 mA∙cm⁻², a Voc of 1.06 V, and a fill factor of 0.78, corresponding to an overall conversion efficiency of 19.12% (the control device of spiro-OMeTAD, 17.69%). In addition, the PCEs of the LY-1 PSC devices underwent decays of only 90% and 74.8% of their original values after 10 and 30 days, respectively, under an Ar atmosphere.

Electron donor–acceptor (EDA) complexes are interesting chemical species that function as molecular complexes. In this context, chemists have actively studies the use of halogen bonding as a noncovalent interaction in photochemistry. This study focused on developing a direct arylation reaction using aryl radicals generated by photoinduced electron transfer (PET) through halogen-bonding interactions. The study also involves optimizing reaction conditions for a photo induced direct arylation reaction using phenols as halogen bonding acceptor and plausible reaction mechanism. Our results demonstrated that this method provides a facile and efficient approach for synthesizing complex biaryls containing heteroarens using readily available heteroarenes.

This review presents the main metrics developed so far to correlate physical properties of light and its effects on melatonin suppression. Melatonin is a hormone secreted at night and its production is suppressed by exposure to light. In this context, the negative effects of lighting at night and high exposure to light raise the need for a better quantification of these impacts on health. Different light action spectroscopy methodologies have been recently used to characterize the circadian response mediated by melatonin in humans, but there is so far no consensus on a main validated model. While complementary studies are still necessary to reach such an ideal model, here we analyze and compare the results of works that developed and tested metrics based on the absorption curves of human melanopsin, rods and cones, and on the dynamics of melatonin suppression in different light regimes. These studies reveal how the spectral composition, irradiance and temporality of light modulate the function of human melatonin. We present milestones in this research field, together with discussion on the advances, limitations and perspectives of application for distinct available models. Applied to different contexts, this knowledge can bring favorable changes to health in environmental lighting projects, production of ophthalmic lenses, screens, filters, films, and other optical devices.