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15 pages, 2862 KiB

Open AccessArticle

Novel Star-Shaped Viologens Containing Phenyl and Triphenylamine Moieties for Electrochromic Applications

by Radosław Banasz and Monika Wałęsa-Chorab

Molecules 2024, 29(9), 2006; https://doi.org/10.3390/molecules29092006 - 26 Apr 2024

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The two star-shaped viologens containing 1,3,5-substituted phenyl (1) and triphenylamine (2) central cores and n-hexyl chains were synthesized and characterized. Both compounds exhibited promising optoelectronic properties and underwent multiple oxidation/reduction processes resulting in various colors. Four possible redox [...] Read more.

The two star-shaped viologens containing 1,3,5-substituted phenyl (1) and triphenylamine (2) central cores and n-hexyl chains were synthesized and characterized. Both compounds exhibited promising optoelectronic properties and underwent multiple oxidation/reduction processes resulting in various colors. Four possible redox states of tripyridium salt containing a phenyl or triphenylamine core can occur depending on the applied potentials. The wide color range, from colorless through blue, azure to green-gray, was observed during the electrochemical reduction of compound 1. In the case of compound 2, the color change observed during spectroelectrochemical measurements was from yellow to colorless during the cathodic process and from yellow to green during the anodic process. The observed color change for both viologens was reversible. The triphenylamine-cored viologen (2) also exhibited emission in visible range and solvatochromism. It also exhibited luminescence in the solid state when excited with a UV lamp. These studies provide insights into the design of advanced materials for applications in displays. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

15 pages, 4171 KiB

Open AccessArticle

Self-Assembly Behavior, Aggregation Structure, and the Charge Carrier Transport Properties of S-Heterocyclic Annulated Perylene Diimide Derivatives

by Haijie Ben, Gaojie Yan, Yulin Wang, Huiming Zeng, Yuechao Wu, Feng Lin, Junhua Zhao, Wanglong Du, Shaojie Zhang, Shijia Zhou, Jingyu Pu, Milan Ye, Haifeng Ji and Liang Lv

Molecules 2024, 29(9), 1964; https://doi.org/10.3390/molecules29091964 - 25 Apr 2024

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Abstract

The construction of high-performance n-type semiconductors is crucial for the advancement of organic electronics. As an attractive n-type semiconductor, molecular systems based on perylene diimide derivatives (PDIs) have been extensively investigated over recent years. Owing to the fascinating aggregated structure and high performance, [...] Read more.

The construction of high-performance n-type semiconductors is crucial for the advancement of organic electronics. As an attractive n-type semiconductor, molecular systems based on perylene diimide derivatives (PDIs) have been extensively investigated over recent years. Owing to the fascinating aggregated structure and high performance, S-heterocyclic annulated PDIs (SPDIs) are receiving increasing attention. However, the relationship between the structure and the electrical properties of SPDIs has not been deeply revealed, restricting the progress of PDI-based organic electronics. Here, we developed two novel SPDIs with linear and dendronized substituents in the imide position, named linear SPDI and dendronized SPDI, respectively. A series of structural and property characterizations indicated that linear SPDI formed a long-range-ordered crystalline structure based on helical supramolecular columns, while dendronized SPDI, with longer alkyl side chains, formed a 3D-ordered crystalline structure at a low temperature, which transformed into a hexagonal columnar liquid crystal structure at a high temperature. Moreover, no significant charge carrier transport signal was examined for linear SPDI, while dendronized SPDI had a charge carrier mobility of 3.5 × 10⁻³ cm² V⁻¹ s⁻¹ and 2.1 × 10⁻³ cm² V⁻¹ s⁻¹ in the crystalline and liquid crystalline state, respectively. These findings highlight the importance of the structure–function relationship in PDIs, and also offer useful roadmaps for the design of high-performance organic electronics for down-to-earth applications. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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14 pages, 2779 KiB

Open AccessArticle

Construction of a Visible-Light-Response Photocatalysis–Self-Fenton Degradation System of Coupling Industrial Waste Red Mud to Resorcinol–Formaldehyde Resin

by Xiangxiu Lv, Hao Yuan, Kaiqu Sun, Weilong Shi, Chunsheng Li and Feng Guo

Molecules 2024, 29(7), 1514; https://doi.org/10.3390/molecules29071514 - 28 Mar 2024

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Abstract

Heterogeneous photocatalysis–self-Fenton technology is a sustainable strategy for treating organic pollutants in actual water bodies with high-fluent degradation and high mineralization capacity, overcoming the limitations of the safety risks caused by adding external iron sources and hazardous chemicals in the homogeneous Fenton reaction [...] Read more.

Heterogeneous photocatalysis–self-Fenton technology is a sustainable strategy for treating organic pollutants in actual water bodies with high-fluent degradation and high mineralization capacity, overcoming the limitations of the safety risks caused by adding external iron sources and hazardous chemicals in the homogeneous Fenton reaction and injecting high-intensity energy fields in photo-Fenton reaction. Herein, a photo-self-Fenton system based on resorcinol–formaldehyde (RF) resin and red mud (RM) was established to generate hydrogen peroxide (H₂O₂) in situ and transform into hydroxy radical (^•OH) for efficient degradation of tetracycline (TC) under visible light irradiation. The capturing experiments and electron spin resonance (ESR) confirmed that the hinge for the enhanced performance of this system is the superior H₂O₂ yield (499 μM) through the oxygen reduction process (ORR) of the two-step single-electron over the resin and the high concentration of ^•OH due to activation effect of RM. In addition, the Fe²⁺/Fe³⁺ cycles are accelerated by photoelectrons to effectively initiate the photo-self-Fenton reaction. Finally, the possible degradation pathways were proposed via liquid chromatography-mass spectrometry (LC-MS). This study provides a new idea for environmental recovery in a waste-based heterogeneous photocatalytic self-Fenton system. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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14 pages, 3063 KiB

Open AccessArticle

Effects of Ti₃C₂Tx MXene Addition to a Co Complex/Ionic Liquid-Based Electrolyte on the Photovoltaic Performance of Solar Cells

by Ju Hee Gu, Dongho Park, Kyung-Hye Jung, Byung Chul Lee and Yoon Soo Han

Molecules 2024, 29(6), 1340; https://doi.org/10.3390/molecules29061340 - 18 Mar 2024

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Abstract

Redox mediators comprising I⁻, Co³⁺, and Ti₃C₂Tx MXene were applied to dye-sensitized solar cells (DSCs). In the as-prepared DSCs (I-DSCs), wherein hole conduction occurred via the redox reaction of I⁻/I₃⁻ ions, [...] Read more.

Redox mediators comprising I⁻, Co³⁺, and Ti₃C₂Tx MXene were applied to dye-sensitized solar cells (DSCs). In the as-prepared DSCs (I-DSCs), wherein hole conduction occurred via the redox reaction of I⁻/I₃⁻ ions, the power conversion efficiency (PCE) was not altered by the addition of Ti₃C₂Tx MXene. The I-DSCs were exposed to light to produce Co²⁺/Co³⁺-based cells (Co-DSCs), wherein the holes were transferred via the redox reaction of Co²⁺/Co³⁺ ions. A PCE of 9.01% was achieved in a Co-DSC with Ti₃C₂Tx MXene (Ti₃C₂Tx-Co-DSC), which indicated an improvement from the PCE of a bare Co-DSC without Ti₃C₂Tx MXene (7.27%). It was also found that the presence of Ti₃C₂Tx MXene in the redox mediator increased the hole collection, dye regeneration, and electron injection efficiencies of the Ti₃C₂Tx-Co-DSC, leading to an improvement in both the short-circuit current and the PCE when compared with those of the bare Co-DSC without MXene. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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18 pages, 6240 KiB

Open AccessArticle

Chemical-Vapor-Deposition-Synthesized Two-Dimensional Non-Stoichiometric Copper Selenide (β-Cu_2−xSe) for Ultra-Fast Tetracycline Hydrochloride Degradation under Solar Light

by Srijith, Rajashree Konar, Eti Teblum, Vivek Kumar Singh, Madina Telkhozhayeva, Michelangelo Paiardi and Gilbert Daniel Nessim

Molecules 2024, 29(4), 887; https://doi.org/10.3390/molecules29040887 - 17 Feb 2024

Viewed by 653

Abstract

The high concentration of antibiotics in aquatic environments is a serious environmental issue. In response, researchers have explored photocatalytic degradation as a potential solution. Through chemical vapor deposition (CVD), we synthesized copper selenide (β-Cu_2−xSe) and found it an effective catalyst for [...] Read more.

The high concentration of antibiotics in aquatic environments is a serious environmental issue. In response, researchers have explored photocatalytic degradation as a potential solution. Through chemical vapor deposition (CVD), we synthesized copper selenide (β-Cu_2−xSe) and found it an effective catalyst for degrading tetracycline hydrochloride (TC-HCl). The catalyst demonstrated an impressive degradation efficiency of approximately 98% and a reaction rate constant of 3.14 × 10⁻² min⁻¹. Its layered structure, which exposes reactive sites, contributes to excellent stability, interfacial charge transfer efficiency, and visible light absorption capacity. Our investigations confirmed that the principal active species produced by the catalyst comprises O²⁻ radicals, which we verified through trapping experiments and electron paramagnetic resonance (EPR). We also verified the TC-HCl degradation mechanism using high-performance liquid chromatography–mass spectrometry (LC-MS). Our results provide valuable insights into developing the β-Cu_2−xSe catalyst using CVD and its potential applications in environmental remediation. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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12 pages, 3098 KiB

Open AccessArticle

Transient Absorption Spectroscopic Investigation of the Photocyclization–Deprotection Reaction of 3′,5′-Dimethoxybenzoin Fluoride

by Runhui Liang, Yuanchun Li, Kin Cheung Lo, Zhiping Yan, Wenjian Tang, Lili Du and David Lee Phillips

Molecules 2024, 29(4), 842; https://doi.org/10.3390/molecules29040842 - 14 Feb 2024

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Abstract

The 3′,5′-dimethoxybenzoin (DMB) system has been widely investigated as a photoremovable protecting group (PRPG) for the elimination of various functional groups and has been applied in many fields. The photolysis of DMB fluoride leads to a highly efficient photocyclization–deprotection reaction, resulting in a [...] Read more.

The 3′,5′-dimethoxybenzoin (DMB) system has been widely investigated as a photoremovable protecting group (PRPG) for the elimination of various functional groups and has been applied in many fields. The photolysis of DMB fluoride leads to a highly efficient photocyclization–deprotection reaction, resulting in a high yield of 3′,5′-dimethoxybenzofuran (DMBF) in a MeCN solution, while there is a competitive reaction that produces DMB in an aqueous solution. The yield of DMB increased as the volume ratio of water increased. To understand the solvent effect of the photolysis of selected DMB-based compounds, a combination of femtosecond to nanosecond transient absorption spectroscopies (fs-TA and ns-TA), nanosecond time-resolved resonance Raman spectroscopy (ns-TR³) and quantum chemical calculation was employed to study the photophysical and photochemical reaction mechanisms of DMB fluoride in different solutions. Facilitated by the bichromophoric nature of DMB fluoride with electron-donating and -withdrawing chromophores, the cyclized intermediates could be found in a pure MeCN solution. The deprotection of a cyclic biradical intermediate results in the simultaneous formation of DMBF and a cyclic cation species. On the other hand, in aqueous solution, fs-TA experiments revealed that α-keto cations could be observed after excitation directly, which could easily produce the DMB through the addition of a hydroxyl within 8.7 ps. This work provides comprehensive photo-deactivation mechanisms of DMB fluoride in MeCN and aqueous conditions and provides critical insights regarding the biomedical application of DMB-based PRPG compounds. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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9 pages, 3052 KiB

Open AccessCommunication

The Use of Iron-Doped Anatase TiO₂ Nanofibers for Enhanced Photocatalytic Fenton-like Reaction to Degrade Tylosin

by Xiao Wang, Wei Lu, Shangui Zhang, Changqing Guo, Kai Yang, Yan Sun, Yashi Shao, Qiyuan Li, Mingsheng Bu, Lianfeng Wu, Bo Wang and Dongjiang Yang

Molecules 2023, 28(19), 6977; https://doi.org/10.3390/molecules28196977 - 08 Oct 2023

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Abstract

The removal of antibiotics from wastewater to prevent their environmental accumulation is significant for human health and ecosystems. Herein, iron (Fe)-atom-doped anatase TiO₂ nanofibers (Fe-TNs) were manufactured for the photocatalytic Fenton-like decomposition of tylosin (TYL) under LED illumination. Compared with the pristine [...] Read more.

The removal of antibiotics from wastewater to prevent their environmental accumulation is significant for human health and ecosystems. Herein, iron (Fe)-atom-doped anatase TiO₂ nanofibers (Fe-TNs) were manufactured for the photocatalytic Fenton-like decomposition of tylosin (TYL) under LED illumination. Compared with the pristine TiO₂ nanofibers (TNs), the optimized Fe-TNs exhibited improved visible-light-driven photocatalytic Fenton-like activity with a TYL degradation efficiency of 98.5% within 4 h. The effective TYL degradation could be attributed to the expanded optical light absorption and accelerated separation and migration of photogenerated electrons and holes after the introduction of Fe. The photogenerated electrons were highly conducive to the generation of active SO₄^•− radicals as they facilitated Fe(III)/Fe(II) cycles, and to oxidizing TYL. Moreover, the holes could be involved in TYL degradation. Thus, a significant enhancement in TYL degradation could be achieved. This research verifies the use of iron-doped anatase nanofibers as an effective method to synthesize novel photocatalytic Fenton-like catalysts through surface engineering for wastewater remediation. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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22 pages, 4968 KiB

Open AccessArticle

Enhanced Photocatalytic Degradation of Malachite Green Dye Using Silver–Manganese Oxide Nanoparticles

by Zhong Xu, Noor Zada, Fazal Habib, Hamid Ullah, Kashif Hussain, Naveed Ullah, Marwa Bibi, Maria Bibi, Huma Ghani, Suliman Khan, Khitab Hussain, Xinyan Cai and Habib Ullah

Molecules 2023, 28(17), 6241; https://doi.org/10.3390/molecules28176241 - 25 Aug 2023

Cited by 5 | Viewed by 2572

Abstract

Efficient and excellent nanoparticles are required for the degradation of organic dyes in photocatalysis. In this study, silver–manganese oxide nanoparticles (Ag-Mn-NPs) were synthesized through a wet chemical precipitation method and characterized as an advanced catalyst that has enhanced photocatalytic activity under sunlight irradiation. [...] Read more.

Efficient and excellent nanoparticles are required for the degradation of organic dyes in photocatalysis. In this study, silver–manganese oxide nanoparticles (Ag-Mn-NPs) were synthesized through a wet chemical precipitation method and characterized as an advanced catalyst that has enhanced photocatalytic activity under sunlight irradiation. The nanoparticles were characterized using scanning electron microscopy (SEM), XRD, UV–vis light spectra, and energy-dispersive X-ray (EDX) spectroscopy, revealing their spherical and agglomerated form. The EDX spectra confirmed the composition of the nanoparticles, indicating their presence in oxide form. These bimetallic oxide nanoparticles were employed as photocatalysts for the degradation of malachite green (MG) dye under sunlight irradiation in an aqueous medium. The study investigated the effects of various parameters, such as irradiation time, catalyst dosage, recovered catalyst dosage, dye concentration, and pH, on the dye’s photodegradation. The results showed that Ag-Mn oxide nanoparticles exhibited high photocatalytic activity, degrading 92% of the dye in 100 min. A longer irradiation time led to increased dye degradation. Moreover, a higher catalyst dosage resulted in a higher dye degradation percentage, with 91% degradation achieved using 0.0017 g of the photocatalyst in 60 min. Increasing the pH of the medium also enhanced the dye degradation, with 99% degradation achieved at pH 10 in 60 min. However, the photodegradation rate decreased with increasing dye concentration. The Ag-Mn oxide nanoparticles demonstrate excellent potential as a reliable visible-light-responsive photocatalyst for the efficient degradation of organic pollutants in wastewater treatment. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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16 pages, 4359 KiB

Open AccessArticle

Construction of S-Scheme 2D/2D Crystalline Carbon Nitride/BiOIO₃ van der Waals Heterojunction for Boosted Photocatalytic Degradation of Antibiotics

by Xiangyuan Kong, Longwen Cao, Yuxing Shi, Zhouze Chen, Weilong Shi and Xin Du

Molecules 2023, 28(13), 5098; https://doi.org/10.3390/molecules28135098 - 29 Jun 2023

Cited by 5 | Viewed by 1000

Abstract

Utilization of semiconductor photocatalyst materials to degrade pollutants for addressing environmental pollution problems has become a research focus in recent years. In this work, a 2D/2D S-scheme crystalline carbon nitride (CCN)/BiOIO₃ (BOI) van der Waals heterojunction was successfully constructed for effectively enhancing [...] Read more.

Utilization of semiconductor photocatalyst materials to degrade pollutants for addressing environmental pollution problems has become a research focus in recent years. In this work, a 2D/2D S-scheme crystalline carbon nitride (CCN)/BiOIO₃ (BOI) van der Waals heterojunction was successfully constructed for effectively enhancing the degradation efficiency of antibiotic contaminant. The as-synthesized optimal CCN/BOI-3 sample exhibited the highest efficiency of 80% for the photo-degradation of tetracycline (TC, 20 mg/L) after 120 min visible light irradiation, which was significantly higher than that of pure CCN and BOI. The significant improvement in photocatalytic performance is mainly attributed to two aspects: (i) the 2D/2D van der Waals heterojunction can accelerate interface carriers’ separation and transfer and afford sufficient active sites; (ii) the S-scheme heterojunction elevated the redox capacity of CCN/BOI, thus providing a driving force for the degradation reaction. The degradation pathways of TC for the CCN/BOI composite were investigated in detail by liquid chromatography-mass spectrometry (LC-MS) analysis. This work provides a design idea for the development of efficient photocatalysts based on the 2D/2D S-scheme van der Waals heterojunctions. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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Review

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42 pages, 7719 KiB

Open AccessReview

Strategies for Improving Selectivity and Sensitivity of Schiff Base Fluorescent Chemosensors for Toxic and Heavy Metals

by Brian Musikavanhu, Yongdi Liang, Zhaoli Xue, Lei Feng and Long Zhao

Molecules 2023, 28(19), 6960; https://doi.org/10.3390/molecules28196960 - 06 Oct 2023

Cited by 3 | Viewed by 2442

Abstract

Toxic cations, including heavy metals, pose significant environmental and health risks, necessitating the development of reliable detection methods. This review investigates the techniques and approaches used to strengthen the sensitivity and selectivity of Schiff base fluorescent chemosensors designed specifically to detect toxic and [...] Read more.

Toxic cations, including heavy metals, pose significant environmental and health risks, necessitating the development of reliable detection methods. This review investigates the techniques and approaches used to strengthen the sensitivity and selectivity of Schiff base fluorescent chemosensors designed specifically to detect toxic and heavy metal cations. The paper explores a range of strategies, including functional group variations, structural modifications, and the integration of nanomaterials or auxiliary receptors, to amplify the efficiency of these chemosensors. By improving selectivity towards targeted cations and achieving heightened sensitivity and detection limits, consequently, these strategies contribute to the advancement of accurate and efficient detection methods while increasing the range of end-use applications. The findings discussed in this review offer valuable insights into the potential of leveraging Schiff base fluorescent chemosensors for the accurate and reliable detection and monitoring of heavy metal cations in various fields, including environmental monitoring, biomedical research, and industrial safety. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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28 pages, 7554 KiB

Open AccessReview

Photocatalytic Self-Fenton System of g-C₃N₄-Based for Degradation of Emerging Contaminants: A Review of Advances and Prospects

by Zhouze Chen, Yujie Yan, Changyu Lu, Xue Lin, Zhijing Fu, Weilong Shi and Feng Guo

Molecules 2023, 28(15), 5916; https://doi.org/10.3390/molecules28155916 - 06 Aug 2023

Cited by 9 | Viewed by 2147

Abstract

The discharge of emerging pollutants in the industrial process poses a severe threat to the ecological environment and human health. Photocatalytic self-Fenton technology combines the advantages of photocatalysis and Fenton oxidation technology through the in situ generation of hydrogen peroxide (H₂O [...] Read more.

The discharge of emerging pollutants in the industrial process poses a severe threat to the ecological environment and human health. Photocatalytic self-Fenton technology combines the advantages of photocatalysis and Fenton oxidation technology through the in situ generation of hydrogen peroxide (H₂O₂) and interaction with iron (Fe) ions to generate a large number of strong reactive oxygen species (ROS) to effectively degrade pollutants in the environment. Graphite carbon nitride (g-C₃N₄) is considered as the most potential photocatalytic oxygen reduction reaction (ORR) photocatalyst for H₂O₂ production due to its excellent chemical/thermal stability, unique electronic structure, easy manufacturing, and moderate band gap (2.70 eV). Hence, in this review, we briefly introduce the advantages of the photocatalytic self-Fenton and its degradation mechanisms. In addition, the modification strategy of the g-C₃N₄-based photocatalytic self-Fenton system and related applications in environmental remediation are fully discussed and summarized in detail. Finally, the prospects and challenges of the g-C₃N₄-based photocatalytic self-Fenton system are discussed. We believe that this review can promote the construction of novel and efficient photocatalytic self-Fenton systems as well as further application in environmental remediation and other research fields. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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