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The Journal of Chemical Physics Jun 2024Understanding the nonadiabatic dynamics of complex systems is a challenging task in computational photochemistry. Herein, we present an efficient and user-friendly...
Understanding the nonadiabatic dynamics of complex systems is a challenging task in computational photochemistry. Herein, we present an efficient and user-friendly quantum mechanics/molecular mechanics (QM/MM) interface to run on-the-fly nonadiabatic dynamics. Currently, this interface consists of an independent set of codes designed for general-purpose use. Herein, we demonstrate the ability and feasibility of the QM/MM interface by integrating it with our long-term developed JADE package. Tailored to handle nonadiabatic processes in various complex systems, especially condensed phases and protein environments, we delve into the theories, implementations, and applications of on-the-fly QM/MM nonadiabatic dynamics. The QM/MM approach is established within the framework of the additive QM/MM scheme, employing electrostatic embedding, link-atom inclusion, and charge-redistribution schemes to treat the QM/MM boundary. Trajectory surface-hopping dynamics are facilitated using the fewest switches algorithm, encompassing classical and quantum treatments for nuclear and electronic motions, respectively. Finally, we report simulations of nonadiabatic dynamics for two typical systems: azomethane in water and the retinal chromophore PSB3 in a protein environment. Our results not only illustrate the power of the QM/MM program but also reveal the important roles of environmental factors in nonadiabatic processes.
PubMed: 38884395
DOI: 10.1063/5.0215036 -
Chemical Society Reviews Jun 2024Oxidative degradation is a powerful method to degrade plastics into oligomers and small oxidized products. While thermal energy has been conventionally employed as an... (Review)
Review
Oxidative degradation is a powerful method to degrade plastics into oligomers and small oxidized products. While thermal energy has been conventionally employed as an external stimulus, recent advances in photochemistry have enabled photocatalytic oxidative degradation of polymers under mild conditions. This tutorial review presents an overview of oxidative degradation, from its earliest examples to emerging strategies. This review briefly discusses the motivation and the development of thermal oxidative degradation of polymers with a focus on underlying mechanisms. Then, we will examine modern studies primarily relevant to catalytic thermal oxidative degradation and photocatalytic oxidative degradation. Lastly, we highlight some unique studies using unconventional approaches for oxidative polymer degradation, such as electrochemistry.
PubMed: 38884337
DOI: 10.1039/d4cs00407h -
Physical Chemistry Chemical Physics :... Jun 2024Polycyclic aromatic hydrocarbons are an important component of the interstellar medium of galaxies and photochemistry plays a key role in the evolution of these species...
Polycyclic aromatic hydrocarbons are an important component of the interstellar medium of galaxies and photochemistry plays a key role in the evolution of these species in space. Here, we explore the photofragmentation behaviour of the coronene cation (CH˙) using time-of-flight mass spectrometry. The experiments show photodissociation fragmentation channels including the formation of bare carbon clusters (C˙) and hydrocarbon chains (CH). The mass spectrum of coronene is dominated by peaks from C˙ and CH. Density functional theory was used to calculate relative energies, potential dissociation pathways, and possible structures for relevant species. We identify 6-6 → 5-7 ring isomerisation as a key step in the formation of both the bare carbon clusters and the hydrocarbon chains observed in this study. We present the dissociation mechanism outlined here as a potential formation route for C and other astrochemically relevant species.
PubMed: 38884178
DOI: 10.1039/d4cp01301h -
Frontiers in Plant Science 2024Energy efficient lighting strategies have received increased interest from controlled environment producers. Long photoperiods (up to 24 h - continuous lighting (CL)) of...
Energy efficient lighting strategies have received increased interest from controlled environment producers. Long photoperiods (up to 24 h - continuous lighting (CL)) of lower light intensities could be used to achieve the desired daily light integral (DLI) with lower installed light capacity/capital costs and low electricity costs in regions with low night electricity prices. However, plants grown under CL tend to have higher carbohydrate and reactive oxygen species (ROS) levels which may lead to leaf chlorosis and down-regulation of photosynthesis. We hypothesize that the use of dynamic CL using a spectral change and/or light intensity change between day and night can negate CL-injury. In this experiment we set out to assess the impact of CL on pepper plants by subjecting them to white light during the day and up to 150 µmol m s of monochromatic blue light at night while controlling the DLI at the same level. Plants grown under all CL treatments had similar cumulative fruit number and weight compared to the 16h control indicating no reduction in production. Plants grown under CL had higher carbohydrate levels and ROS-scavenging capacity than plants grown under the 16h control. Conversely, the amount of photosynthetic pigment decreased with increasing nighttime blue light intensity. The maximum quantum yield of photosystem II (F/F), a metric often used to measure stress, was unaffected by light treatments. However, when light-adapted, the operating efficiency of photosystem II (ΦPSII) decreased and non-photochemical quenching (NPQ) increased with increasing nighttime blue light intensity. This suggests that both acclimated and instantaneous photochemistry during CL can be altered and is dependent on the nighttime light intensity. Furthermore, light-adapted chlorophyll fluorescence measurements may be more adept at detecting altered photochemical states than the conventional stress metric using dark-adapted measurements.
PubMed: 38882573
DOI: 10.3389/fpls.2024.1372886 -
Scientific Reports Jun 2024This study presents a thorough spectroscopic analysis of TiO-Pt systems under LED irradiation, with a focus on elucidating the photodeposition process of Pt...
This study presents a thorough spectroscopic analysis of TiO-Pt systems under LED irradiation, with a focus on elucidating the photodeposition process of Pt nanoparticles onto TiO surfaces. The methodology leverages an innovative LED photoreactor tailored to a specific spectral range, enabling precise characterization of the excitation spectrum of TiO-Pt composites. Through the identification of Pt precursor species and their excitation under LED-UV light, a photodeposition mechanism is proposed involving concurrent excitation of both the TiO semiconductor and the HPtCl precursor. The LED photoreactors are employed to scrutinize the excitation profile of TiO-Pt materials, revealing that the incorporation of Pt nanoparticles does not expand TiO's absorption spectrum. Furthermore, UV-A exposure in the absence of Pt did not induce the formation of surface defects, underscoring the lack of visible light activity in TiO-Pt systems. Spectroscopic analyses, complemented by naproxen photooxidation experiments, indicate the absence of a significant plasmonic effect in Pt nanoparticles within the experimental framework. Mass spectroscopy results corroborate the presence of distinct naproxen degradation pathways, suggesting minimal influence from photocatalyst properties. This research provides a detailed spectroscopic insight into TiO-Pt photocatalysis, enriching the knowledge of photocatalytic materials in LED lighting.
PubMed: 38879712
DOI: 10.1038/s41598-024-64748-4 -
Spectrochimica Acta. Part A, Molecular... Jun 2024We theoretically investigate the photoionization scenarios of molecular complexes involving cyclopentadiene and cyanocyclopentadiene bound to water dimers. Using...
A theoretical study of the photochemistry of 1,3-cyclopentadiene and its cyano derivatives bound to a water dimer: Assessing reactivity of ionized clusters and possible photoproducts.
We theoretically investigate the photoionization scenarios of molecular complexes involving cyclopentadiene and cyanocyclopentadiene bound to water dimers. Using electronic structure calculations within density-functional theory (DFT) and time dependent DFT (TD-DFT), we explore the potential photochemical pathways following ionization, and determine the charge transfer excitations related to the possible subsequent reactions. Our findings suggest that the investigated photochemical pathways of the hydrated complexes take place in two well-defined ultraviolet regions: (i) 8.2-9.5 eV for the cyclic compounds and (ii) 11.2-11.4 eV for the bound water dimer. We quantify how H-bonding effects can influence the photoionization channels. Before forming possible photoproducts, we also examine the regiospecificity of OH addition to 1,3-cyclopentadiene and its cyano derivatives We analyze our results in light of photoionization studies of jet-cooled molecular complexes and possible implications in astrochemical environments.
PubMed: 38878722
DOI: 10.1016/j.saa.2024.124637 -
Ultrasonics Sonochemistry Jun 20241,3,5-triazine derivatives are useful compounds with potential applications in various branches of chemical industry, including pharmaceutical chemistry, cosmetic...
1,3,5-triazine derivatives are useful compounds with potential applications in various branches of chemical industry, including pharmaceutical chemistry, cosmetic chemistry, photochemistry, and organic chemistry. Due to the growing environmental requirements on conducting efficient, economical, and safe syntheses, development of new methods for synthesizing organic compounds is highly desirable. In this publication, we present a protocol for the synthesis of 1,3,5-triazine derivatives using a sonochemical approach. In as little as 5 min, it is possible to obtain most of the investigated compounds with a yield of over 75%. An undeniable advantage of this method, besides its short time, is the use of water as the solvent. Furthermore, we provide examples that the sonochemical method may be more versatile than the competing microwave method. Analysis conducted using the DOZN 2.0 tool revealed that in terms of the 12 principles of green chemistry, the developed sonochemical method is 13 times "greener" than the classical one. Additionally, it has been demonstrated that the investigated molecules are attractive for their application as drug-like compounds.
PubMed: 38878716
DOI: 10.1016/j.ultsonch.2024.106951 -
Angewandte Chemie (International Ed. in... Jun 2024In this work, six benzothioxanthene-based oxime esters were employed as photoinitiators for photopolymerization with visible light (LED) and sunlight. Their abilities to...
High Photoinitiating Efficiency of Benzothioxanthene-based Oxime Esters in Photopolymerization via Photocleavage and/or Single Electron Transfer under Visible Light and Sunlight.
In this work, six benzothioxanthene-based oxime esters were employed as photoinitiators for photopolymerization with visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating system with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene-based oxime esters were systematically tested under excitation with low-intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, to the polymerization tests done under artificial light, different benzothioxanthene-based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures.
PubMed: 38877857
DOI: 10.1002/anie.202405337 -
Advanced Science (Weinheim,... Jun 2024White light-emitting diodes (WLEDs) with high color-rendering index (CRI, >90) are important for backlight displays and solid-state lighting applications. Although the...
White light-emitting diodes (WLEDs) with high color-rendering index (CRI, >90) are important for backlight displays and solid-state lighting applications. Although the well-developed colloidal quantum dots (QDs) based on heavy metals such as cadmium and lead are promising candidates for WLEDs, the low CRI still remains a significant limitation. In addition, the severe toxicity of heavy metals greatly limits their widespread use. Herein, the study demonstrates low-cost and environmentally friendly carbon quantum dots (CQDs)-based WLEDs that exhibit a high CRI of 94.33, surpassing that of conventional cadmium/lead-containing QD-based WLEDs. This achievement is attained through the employment of a binary host-induced exciplex strategy. The high hole/electron mobility and suitable energy levels of the donor and acceptor give rise to a broadband orange-yellow emission stemming from the exciplex. As the host, the binary exciplex is capable of contributing blue and orange-yellow emission components while efficiently mitigating the aggregation-induced quenching of CQDs. Meanwhile, CQDs effectively address the deep-red emission gap, enabling the realization of CQDs-based WLEDs with high CRI. These WLEDs also exhibit a remarkably low turn-on voltage of 2.8 V, a maximum luminance exceeding 2000 cd m , a correlated color temperature of 4976 K, and Commission Internationale de l'Eclairage coordinates of (0.34, 0.32).
PubMed: 38872266
DOI: 10.1002/advs.202404485 -
Nature Communications Jun 2024Direct solar-to-hydrogen conversion from pure water using all-organic heterogeneous catalysts remains elusive. The challenges are twofold: (i) full-band low-frequent...
Direct solar-to-hydrogen conversion from pure water using all-organic heterogeneous catalysts remains elusive. The challenges are twofold: (i) full-band low-frequent photons in the solar spectrum cannot be harnessed into a unified S excited state for water-splitting based on the common Kasha-allowed S → S excitation; (ii) the H → H evolution suffers the high overpotential on pristine organic surfaces. Here, we report an organic molecular crystal nanobelt through the self-assembly of spin-one open-shell perylene diimide diradical anions (:PDI) and their tautomeric spin-zero closed-shell quinoid isomers (PDI). The self-assembled :PDI/PDI crystal nanobelt alters the spin-dependent excitation evolution, leading to spin-allowed SS → (TT) → T + T singlet fission under visible-light (420 nm~700 nm) and a spin-forbidden S → T transition under near-infrared (700 nm~1100 nm) within spin-hybrid chromophores. With a triplet-triplet annihilation upconversion, a newly formed S excited state on the diradical-quinoid hybrid induces the H reduction through a favorable hydrophilic diradical-mediated electron transfer, which enables simultaneous H and O production from pure water with an average apparent quantum yield over 1.5% under the visible to near-infrared solar spectrum.
PubMed: 38871750
DOI: 10.1038/s41467-024-49511-7