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Photochem
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Feature Papers in Photochemistry II
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Feature Papers in Photochemistry II

A special issue of Photochem (ISSN 2673-7256).

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 15184

Special Issue Editors

Prof. Dr. Marcelo Guzman

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Guest Editor
Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
Interests: environmental photochemistry; interfacial oxidations; environmental monitoring; prebiotic chemistry; photocatalytic CO2 reduction; environmental chemistry
Special Issues, Collections and Topics in MDPI journals
Dr. Vincenzo Vaiano

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Guest Editor
Department of Industrial Engineering, University Salerno, Via Giovanni Paolo 2 132, I-84084 Fisciano, Salerno, Italy
Interests: photocatalysis for sustainable chemistry; photocatalytic and photo-Fenton processes for pollutants removal in wastewater; catalytic combustion of sewage sludge; decomposition and oxidative decomposition of H2S; hydrolysis of COS in the liquid phase
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Rui Fausto

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Guest Editor
Department of Chemistry, Coimbra Chemistry Center (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal
Interests: photochemistry; molecular cryo- and biospectroscopy; quantum chemistry; molecular structure; photophysics; chemometrics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Following the success of the previous Special Issue, it is our pleasure to announce a new Special Issue, "Feature Papers in Photochemistry II." This Special Issue is designed to publish high-quality papers in Photochem, a journal dedicated to recent advances in the research area of photochemistry. This Special Issue engages in, but is not limited to, the following topics: interactions of UV, visible and IR radiation with molecules and materials. Photochemistry has important associations across a wide spectrum of science, including physics, organic and inorganic chemistry, catalysis, materials science, biology, and medicine.

This Special Issue will present a collection of both research articles and review articles highlighting interesting results in the field of photochemistry.

Dr. Marcelo Guzman
Dr. Vincenzo Vaiano
Prof. Dr. Rui Fausto
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photochem is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • photocatalysis
  • photoreduction
  • photochemical electron transfer
  • visible or solar light
  • water and wastewater treatment
  • gaseous pollutant removal
  • energy conversion
  • spectroscopy

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Related Special Issues

Published Papers (9 papers)

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Editorial

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7 pages, 200 KiB  
Editorial
Feature Papers in Photochemistry
by Marcelo I. Guzman
Photochem 2024, 4(4), 511-517; https://doi.org/10.3390/photochem4040032 - 10 Dec 2024
Viewed by 353
Abstract
As the Special Issues “Feature Papers in Photochemistry” and “Feature Papers in Photochemistry II” conclude, it is crucial to acknowledge the remarkable progress and persistent gaps that continue to shape the journey of photochemistry research [...] Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)

Research

Jump to: Editorial

19 pages, 12218 KiB  
Article
Excited-State Dynamics of Carbazole and tert-Butyl-Carbazole in Thin Films
by Konstantin Moritz Knötig, Domenic Gust, Kawon Oum and Thomas Lenzer
Photochem 2024, 4(2), 179-197; https://doi.org/10.3390/photochem4020011 - 9 Apr 2024
Viewed by 1146
Abstract
Thin films of carbazole (Cz) derivatives are frequently used in organic electronics, such as organic light-emitting diodes (OLEDs). Because of the proximity of the Cz units, the excited-state relaxation in such films is complicated, as intermolecular pathways, such as singlet–singlet annihilation (SSA), kinetically [...] Read more.
Thin films of carbazole (Cz) derivatives are frequently used in organic electronics, such as organic light-emitting diodes (OLEDs). Because of the proximity of the Cz units, the excited-state relaxation in such films is complicated, as intermolecular pathways, such as singlet–singlet annihilation (SSA), kinetically compete with the emission. Here, we provide an investigation of two benchmark systems employing neat carbazole and 3,6-di-tert-butylcarbazole (t-Bu-Cz) films and also their thin film blends with poly(methyl methacrylate) (PMMA). These are investigated by a combination of atomic force microscopy (AFM), femtosecond and nanosecond transient absorption spectroscopy (fs-TA and ns-TA) and time-resolved fluorescence. Excitonic J-aggregate-type features are observed in the steady-state absorption and emission spectra of the neat films. The S1 state shows a broad excited-state absorption (ESA) spanning the entire UV–Vis–NIR range. At high S1 exciton number densities of about 4 × 1018 cm−3, bimolecular diffusive S1–S1 annihilation is found to be the dominant SSA process in the neat films with a rate constant in the range of 1–2 × 10−8 cm3 s−1. SSA produces highly vibrationally excited molecules in the electronic ground state (S0*), which cool down slowly by heat transfer to the quartz substrate. The results provide relevant photophysical insight for a better microscopic understanding of carbazole relaxation in thin-film environments. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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16 pages, 7427 KiB  
Article
Excited-State Dynamics of Carbazole and tert-Butyl-Carbazole in Organic Solvents
by Konstantin Moritz Knötig, Domenic Gust, Thomas Lenzer and Kawon Oum
Photochem 2024, 4(2), 163-178; https://doi.org/10.3390/photochem4020010 - 30 Mar 2024
Cited by 1 | Viewed by 1435
Abstract
Carbazole-based molecular units are ubiquitous in organic optoelectronic materials; however, the excited-state relaxation of these compounds is still underexplored. Here, we provide a detailed investigation of carbazole (Cz) and 3,6-di-tert-butylcarbazole (t-Bu-Cz) in organic solvents using femtosecond and nanosecond UV–Vis–NIR [...] Read more.
Carbazole-based molecular units are ubiquitous in organic optoelectronic materials; however, the excited-state relaxation of these compounds is still underexplored. Here, we provide a detailed investigation of carbazole (Cz) and 3,6-di-tert-butylcarbazole (t-Bu-Cz) in organic solvents using femtosecond and nanosecond UV–Vis–NIR transient absorption spectroscopy, as well as time-resolved fluorescence experiments upon photoexcitation in the deep-UV range. The initially prepared Sx singlet state has a (sub-)picosecond lifetime and decays to the S1 state by internal conversion (IC). The S1 state exhibits absorption peaks at 350, 600 and 1100 nm and has a lifetime of 13–15 ns, which is weakly dependent on the solvent. Energy transfer from vibrationally hot S1 molecules (S1*) to the surrounding solvent molecules takes place with a time constant of 8–20 ps. The T1 triplet state is populated by intersystem crossing (ISC) from S1 with a typical quantum yield of 51–56% and shows a lifetime which is typically in the few microseconds regime. The S1 and T1 states of both carbazole compounds in solution are strongly quenched by O2. Two-photon excitation leads to the formation of a small amount of the respective radical cation. The influence of the tert-butyl substituents on the photophysics is relatively weak and mainly reflects itself in a small increase in the Stokes shift. The results provide important photophysical information for the interpretation of carbazole relaxation in more complex environments. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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10 pages, 1492 KiB  
Article
Evaluation of MAA Analogues as Potential Candidates to Increase Photostability in Sunscreen Formulations
by Jacobo Soilán, Leonardo López-Cóndor, Beatriz Peñín, José Aguilera, María Victoria de Gálvez, Diego Sampedro and Raúl Losantos
Photochem 2024, 4(1), 128-137; https://doi.org/10.3390/photochem4010007 - 6 Feb 2024
Cited by 2 | Viewed by 1026
Abstract
Avobenzone is one of the most widely used sunscreens in skin care formulations, but suffers from some drawbacks, including photo instability. To mitigate this critical issue, the use of octocrylene as a stabilizer is a common approach in these products. However, octocrylene has [...] Read more.
Avobenzone is one of the most widely used sunscreens in skin care formulations, but suffers from some drawbacks, including photo instability. To mitigate this critical issue, the use of octocrylene as a stabilizer is a common approach in these products. However, octocrylene has been recently demonstrated to show potential phototoxicity. The aim of this work is to analyze the performance of a series of mycosporine-like amino acid (MAA)-inspired compounds to act as avobenzone stabilizers as an alternative to octocrylene. Different avobenzone/MAA analogue combinations included in galenic formulations were followed under increasing doses of solar-simulated UV radiation. Some of the synthetic MAA analogues analyzed were able to increase by up to two times the UV dose required for 50% of avobenzone photobleaching. We propose some of these MAA analogues as new candidates to act as avobenzone-stabilizing compounds in addition to their UV absorbance and antioxidant properties, together with a facile synthesis. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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54 pages, 2124 KiB  
Article
Inverse Problems in Pump–Probe Spectroscopy
by Denis S. Tikhonov, Diksha Garg and Melanie Schnell
Photochem 2024, 4(1), 57-110; https://doi.org/10.3390/photochem4010005 - 31 Jan 2024
Cited by 2 | Viewed by 1472
Abstract
Ultrafast pump–probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates’ lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. [...] Read more.
Ultrafast pump–probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates’ lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. This article describes a consistent approach for solving this inverse problem that avoids the common obstacles of simple least-squares fitting that can lead to unreliable results. The presented approach is based on the regularized Markov Chain Monte-Carlo sampling for the strongly nonlinear parameters, allowing for a straightforward solution of the ill-posed nonlinear inverse problem. The software to implement the described fitting routine is introduced and the numerical examples of its application are given. We will also touch on critical experimental parameters, such as the temporal overlap of pulses and cross-correlation time and their connection to the minimal reachable time resolution. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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12 pages, 2103 KiB  
Article
E–Z Photoisomerization in Proton-Modulated Photoswitchable Merocyanine Based on Benzothiazolium and o-Hydroxynaphthalene Platform
by Aleksey A. Vasilev, Stanislav Baluschev, Sonia Ilieva and Diana Cheshmedzhieva
Photochem 2023, 3(2), 301-312; https://doi.org/10.3390/photochem3020018 - 19 Jun 2023
Viewed by 1789
Abstract
The potential of E–Z photoisomerization in molecular organic light-to-thermal conversion and storage in an E–styryl merocyanine system was studied in a polar acidic medium. A photoswitchable styryl merocyanine dye (E)-2-(2-(2-hydroxynaphthalen-1-yl)vinyl)-3,5-dimethylbenzo[d]thiazol-3-ium iodide was synthesized for the first [...] Read more.
The potential of E–Z photoisomerization in molecular organic light-to-thermal conversion and storage in an E–styryl merocyanine system was studied in a polar acidic medium. A photoswitchable styryl merocyanine dye (E)-2-(2-(2-hydroxynaphthalen-1-yl)vinyl)-3,5-dimethylbenzo[d]thiazol-3-ium iodide was synthesized for the first time. The reversible E–Z photoisomerisation of the dye was investigated using UV-Vis spectroscopy and DFT calculations. E–Z isomerization was induced through the use of visible light irradiation (λ = 450 nm). The obtained experimental and theoretical results confirm the applicability of the Z and E isomers for proton-triggered light harvesting. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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13 pages, 1692 KiB  
Article
Effect of Benzophenone Type UV Filters on Photodegradation of Co-existing Sulfamethoxazole in Water
by Dilini Kodikara, Zhongyu Guo and Chihiro Yoshimura
Photochem 2023, 3(2), 288-300; https://doi.org/10.3390/photochem3020017 - 1 Jun 2023
Cited by 1 | Viewed by 2171
Abstract
Benzophenones (BPs) frequently occur in water environments, and they are able to both screen UV light and to sensitize reactive intermediate (RI) production. However, BPs have largely been overlooked as a background water component when studying photodegradation of co-existing organic micropollutants (OMPs). Therefore, [...] Read more.
Benzophenones (BPs) frequently occur in water environments, and they are able to both screen UV light and to sensitize reactive intermediate (RI) production. However, BPs have largely been overlooked as a background water component when studying photodegradation of co-existing organic micropollutants (OMPs). Therefore, in this study, we investigated the influence of BP and its derivative oxybenzone (BP3) on the degradation of the co-existing model OMP sulfamethoxazole (SMX). A series of photodegradation experiments were conducted covering a range of BPs concentrations in μg/L levels, and the degradation of 1.00 μM of SMX was studied. The addition of BP at 0.10 μM, 0.25 μM, and 0.30 μM, and BP3 at 0.10 μM and 0.25 μM, significantly increased the first order degradation rate constant of 1.00 μM of SMX (kobs(BP)) by 36.2%, 50.0%, 7.3%, 31.5%, and 36.2% respectively, compared to that in the absence of any BPs. The maximum indirect photodegradation induced by BP and BP3 reached 33.8% and 27.7%, respectively, as a percentage of the observed SMX degradation rate at the [BPs]/[SMX] ratio of 0.25. In general, triplet excited dissolved organic matter (3SMX*, 3BP*, and 3BP3*) played the major role in the photosensitizing ability of BPs. The results further implied that the increase of SMX degradation at the molar ratio of 0.25 was possibly due to 3BP* for the mixture of SMX and BP. Overall, this study revealed the sensitizing ability of BP and BP3 on the co-existing OMP, SMX, in water for the first time. Our findings can be applied to other BP type UV filters which are similar to BP and PB3 in molecular structure. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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14 pages, 6942 KiB  
Article
Synthesis and Characterization of New Tetradentate N2O2-Based Schiff’s Base Cu (II) Complexes for Dye Photodegradation
by Rohini Vallavoju, Ranjith Kore, Radhika Parikirala, Mahesh Subburu, Ramesh Gade, Vipin Kumar, Matta Raghavender, Prabhakar Chetti and Someshwar Pola
Photochem 2023, 3(2), 274-287; https://doi.org/10.3390/photochem3020016 - 11 May 2023
Cited by 3 | Viewed by 2484
Abstract
We have reported tetradentate ligands (salophen) coordinated with N and O atoms that led to the Cu (II) complexes. These Cu (II) complexes (C-1 and C-2) were firstly established by using elemental analysis and confirmed by mass spectra. At the same time, the [...] Read more.
We have reported tetradentate ligands (salophen) coordinated with N and O atoms that led to the Cu (II) complexes. These Cu (II) complexes (C-1 and C-2) were firstly established by using elemental analysis and confirmed by mass spectra. At the same time, the characterization of C-1 and C-2 complexes is performed by using several spectroscopic methods and morphological analysis. The bandgap values of the C-1 and C-2 complexes are evaluated with UV-vis DRS spectra. The PL spectral data and photocurrent curves clearly indicated the small recombination rate of the hole–electron pair. The synthesized C-1 and C-2 complexes’ photocatalytic properties were examined for the degradation of cationic dyes such as methylene blue (MB λmax.= 654 nm) and methyl violet (MV λmax.= 590 nm) below visible-light action. The C-2 complex is more active than the C-1 complex because of its high photostability, small band-gap energy, and low recombination rate for hole–electron pair separation, and improved visible-light character, which encourages the generation of hydroxyl radical species throughout the photodegradation process. Scavenger probes were used to identify the dynamic species for the photodegradation of dyes, and a mechanism investigation was established. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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11 pages, 1409 KiB  
Article
Photoprotective Effects of Selected Polyphenols and Antioxidants on Naproxen Photodegradability in the Solid-State
by Kohei Kawabata, Ayano Miyoshi and Hiroyuki Nishi
Photochem 2022, 2(4), 880-890; https://doi.org/10.3390/photochem2040056 - 6 Nov 2022
Cited by 6 | Viewed by 1898
Abstract
Photostabilization is an important methodology to ensure both the quality and quantity of photodegradable pharmaceuticals. The purpose of our study is to develop a photostabilization strategy focused on the addition of photostabilizers. In this study, the protective effects of selected polyphenols and antioxidants [...] Read more.
Photostabilization is an important methodology to ensure both the quality and quantity of photodegradable pharmaceuticals. The purpose of our study is to develop a photostabilization strategy focused on the addition of photostabilizers. In this study, the protective effects of selected polyphenols and antioxidants on naproxen (NPX) photodegradation in the solid state were evaluated. Residual amounts of NPX were determined by high-performance liquid chromatography (HPLC), and the protective effects of tested additives on NPX photodegradation induced by ultraviolet light (UV) irradiation were evaluated. As a result, quercetin, curcumin, and resveratrol suppressed NPX photodegradation completely. When they were mixed with NPX, the residual amounts of NPX after UV irradiation were significantly higher compared to that without additives, and comparable to those of their control samples. In addition, to clarify the mechanisms of the highly protective effects of these additives on NPX photodegradation, their antioxidative potencies, and UV filtering potencies were determined. There was no correlation between photoprotective effects and antioxidative potencies among selected polyphenols and antioxidants although photoprotective additives showed more significant UV absorption compared to NPX. From these results, it is clarified that a higher UV filtering activity is necessary for a better photostabilizer to photodegradable pharmaceuticals in the solid state. Full article
(This article belongs to the Special Issue Feature Papers in Photochemistry II)
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