Molecules

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13 pages, 3309 KiB

Open AccessArticle

Modulating the Conductivity of Light-Responsive Ionic Liquid Crystals

by Umama Bendaoud, Pradip K. Bhowmik, Si L. Chen, Haesook Han, Seonghyeok L. Cox, Jasmin Liebsch, M. Blanca Ros, Thamil Selvi Velayutham, Nurul Fadhilah Kamalul Aripin and Alfonso Martinez-Felipe

Molecules 2024, 29(18), 4459; https://doi.org/10.3390/molecules29184459 - 20 Sep 2024

Viewed by 742

Abstract

In this work, we describe the phase behaviour and the dielectric and conductivity response of new light-responsive ionic liquid crystals, ILCs, which can be applied as controllable electrolytes. The materials include two different dicationic viologens, the asymmetric 6BP18 and the symmetric EV2ON(Tf)₂ [...] Read more.

In this work, we describe the phase behaviour and the dielectric and conductivity response of new light-responsive ionic liquid crystals, ILCs, which can be applied as controllable electrolytes. The materials include two different dicationic viologens, the asymmetric 6BP18 and the symmetric EV2ON(Tf)₂, containing bistriflimide as the counterions, mixed with 5% and 50% molar, respectively, of one new photoresponsive mesogen called CNAzO14. These mixtures exhibit liquid crystal behaviour, light responsiveness through the E-Z photoisomerisation of the azobenzene groups in CNAzO14, and strong dielectric responses. The 5%-CNAzO14/Ev2ON(Tf)₂ mixture displays direct current conductivities in the 10⁻⁷ S·cm⁻¹ range, which can be increased by a two-fold factor upon the irradiation of UV light at 365 nm. Our findings set the grounds for designing new smart ionic soft materials with nanostructures that can be tuned and used for energy conversion and storage applications. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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17 pages, 2698 KiB

Open AccessArticle

Assessment of Optical and Phonon Characteristics in MOCVD-Grown (Al_xGa_1−x)_0.5In_0.5P/n⁺-GaAs Epifilms

by Devki N. Talwar and Zhe Chuan Feng

Molecules 2024, 29(17), 4188; https://doi.org/10.3390/molecules29174188 - 4 Sep 2024

Viewed by 707

Abstract

Quaternary (Al_xGa_1−x)_yIn_1−yP alloys grown on GaAs substrates have recently gained considerable interest in photonics for improving visible light-emitting diodes, laser diodes, and photodetectors. With two degrees of freedom (x, y) and keeping growth on a [...] Read more.

Quaternary (Al_xGa_1−x)_yIn_1−yP alloys grown on GaAs substrates have recently gained considerable interest in photonics for improving visible light-emitting diodes, laser diodes, and photodetectors. With two degrees of freedom (x, y) and keeping growth on a lattice-matched GaAs substrate, the (Al_xGa_1−x)_0.5In_0.5P alloys are used for tuning structural, phonon, and optical characteristics in different energy regions from far-infrared (FIR) → near-infrared (NIR) → ultraviolet (UV). Despite the successful growth of (Al_xGa_1−x)_0.5In_0.5P/n⁺-GaAs epilayers, limited optical, phonon, and structural characteristics exist. Here, we report our results of carefully examined optical and vibrational properties on highly disordered alloys using temperature-dependent photoluminescence (TD-PL), Raman scattering spectroscopy (RSS), and Fourier-transform infrared reflectivity (FTIR). Macroscopic models were meticulously employed to analyze the TD-PL, RSS, and FTIR data of the (Al_0.24Ga_0.76)_0.5In_0.5P/n⁺-GaAs epilayers to comprehend the energy-dependent characteristics. The Raman scattering and FTIR results of phonons helped analyze the reflectivity spectra in the FIR region. Optical constants were carefully integrated in the transfer matrix method for evaluating the reflectivity

R (E)

and transmission

T (E)

spectra in the NIR → UV regions, validating the TD-PL measurements of bandgap energies

(E_{g}^{P L})

. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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13 pages, 5120 KiB

Open AccessArticle

Cs-Doped WO₃ with Enhanced Conduction Band for Efficient Photocatalytic Oxygen Evolution Reaction Driven by Long-Wavelength Visible Light

by Dong Li, Siyu Tian, Qiuhua Qian, Caiyun Gao, Hongfang Shen and Fei Han

Molecules 2024, 29(13), 3126; https://doi.org/10.3390/molecules29133126 - 30 Jun 2024

Viewed by 1000

Abstract

Cesium doped WO₃ (Cs-WO₃) photocatalyst with high and stable oxidation activity was successfully synthesized by a one-step hydrothermal method using Cs₂CO₃ as the doped metal ion source and tungstic acid (H₂WO₄) as the [...] Read more.

Cesium doped WO₃ (Cs-WO₃) photocatalyst with high and stable oxidation activity was successfully synthesized by a one-step hydrothermal method using Cs₂CO₃ as the doped metal ion source and tungstic acid (H₂WO₄) as the tungsten source. A series of analytical characterization tools and oxygen precipitation activity tests were used to compare the effects of different additions of Cs₂CO₃ on the crystal structure and microscopic morphologies. The UV–visible diffuse reflectance spectra (DRS) of Cs-doped material exhibited a significant red shift in the absorption edge with new shoulders appearing at 440–520 nm. The formation of an oxygen vacancy was confirmed in Cs-WO₃ by the EPR signal, which can effectively regulate the electronic structure of the catalyst surface and contribute to improving the activity of the oxygen evolution reaction (OER). The photocatalytic OER results showed that the Cs-WO₃-0.1 exhibited the optimal oxygen precipitation activity, reaching 58.28 µmol at 6 h, which was greater than six times higher than that of WO₃-0 (9.76 μmol). It can be attributed to the synergistic effect of the increase in the conduction band position of Cs-WO₃-0.1 (0.11 V) and oxygen vacancies compared to WO₃-0, which accelerate the electron conduction rate and slow down the rapid compounding of photogenerated electrons–holes, improving the water-catalytic oxygen precipitation activity of WO₃. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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13 pages, 18058 KiB

Open AccessArticle

A Zn(II) Coordination Polymer for Fluorescent Turn-Off Selective Sensing of Heavy Metal Cation and Toxic Inorganic Anions

by Yaxin Li, Mouyi Zhang, Ying Wang, Lei Guan, Di Zhao, Xinyu Hao and Yuting Guo

Molecules 2024, 29(12), 2943; https://doi.org/10.3390/molecules29122943 - 20 Jun 2024

Viewed by 676

Abstract

A novel coordination polymer [Zn(atyha)₂]_n (1) (Hatyha = 2-(2-aminothiazole-4-yl)-2- hydroxyiminoacetic acid) was constructed by hydrothermal reaction of Zn²⁺ with Hatyha ligand. CP 1 exhibits a 2D (4,4)-connected topological framework with Schläfli symbol of {4⁴·6² [...] Read more.

A novel coordination polymer [Zn(atyha)₂]_n (1) (Hatyha = 2-(2-aminothiazole-4-yl)-2- hydroxyiminoacetic acid) was constructed by hydrothermal reaction of Zn²⁺ with Hatyha ligand. CP 1 exhibits a 2D (4,4)-connected topological framework with Schläfli symbol of {4⁴·6²}, where atyha⁻ anions serve as tridentate ligands, bridging with Zn²⁺ through carboxylate, thiazole and oxime groups. CP 1 displays a strong ligand-based photoluminescence at 390 nm in the solid state, and remains significantly structurally stable in water. Interestingly, it can be utilized as a fluorescent probe for selective and sensitive sensing of Fe³⁺, Cr₂O₇²⁻ and MnO₄⁻ through the fluorescent turn-off effect with limit of detection (LOD) of 3.66 × 10⁻⁶, 2.38 × 10⁻⁵ and 2.94 × 10⁻⁶ M, respectively. Moreover, the efficient recyclability for detection of Fe³⁺ and Cr₂O₇²⁻ is better than that for MnO₄⁻. The mechanisms of fluorescent quenching involve reversible overlap of UV-Vis absorption bands of the analytes (Fe³⁺, Cr₂O₇²⁻ and MnO₄⁻) with fluorescence excitation and emission bands for CP 1, respectively. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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14 pages, 2316 KiB

Open AccessArticle

AgIn₅S₈/g-C₃N₄ Composite Photocatalyst Coupled with Low-Temperature Plasma-Enhanced Degradation of Hydroxypropyl-Guar-Simulated Oilfield Wastewater

by Xiang Li, Yuhang Zhang, Yiling Wang, Li Zhu, Yuhang Liu and Lingxing Wang

Molecules 2024, 29(12), 2862; https://doi.org/10.3390/molecules29122862 - 16 Jun 2024

Viewed by 701

Abstract

The effective treatment and recovery of fracturing wastewater has always been one of the difficult problems to be solved in oilfield wastewater treatment. Accordingly, in this paper, photocatalytic-coupled low-temperature plasma technology was used to degrade the simulated wastewater containing hydroxypropyl guar, the main [...] Read more.

The effective treatment and recovery of fracturing wastewater has always been one of the difficult problems to be solved in oilfield wastewater treatment. Accordingly, in this paper, photocatalytic-coupled low-temperature plasma technology was used to degrade the simulated wastewater containing hydroxypropyl guar, the main component of fracturing fluid. Results indicated that hydroxypropyl-guar wastewater could be degraded to a certain extent by either photocatalytic technology or plasma technology; the chemical oxygen demand and viscosity of the treated wastewater under two single-technique optimal conditions were 781 mg·L⁻¹, 0.79 mPa·s⁻¹ and 1296 mg·L⁻¹, 1.01 mPa·s⁻¹, respectively. Furthermore, the effective coupling of AgIn₅S₈/gC₃N₄ photocatalysis and dielectric-barrier discharge–low-temperature plasma not only enhanced the degradation degree of hydroxypropyl guar but also improved its degradation efficiency. Under the optimal conditions of coupling treatment, the hydroxypropyl-guar wastewater achieved the effect of a single treatment within 6 min, and the chemical oxygen demand and viscosity of the treated wastewater reduced to below 490 mg·L⁻¹ and 0.65 mPa·s⁻¹, respectively. In the process of coupled treatment, the AgIn₅S₈/gC₃N₄ could directly absorb the light and strong electric field generated by the system discharge and play an important role in the photocatalytic degradation, thus effectively improving the energy utilization rate of the discharge system and enhancing the degradation efficiency of hydroxypropyl guar. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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21 pages, 5779 KiB

Open AccessArticle

Photochemical Transformations of Diverse Biologically Active Resveratrol Analogs in Batch and Flow Reactors

by Milena Mlakić, Hana Perinić, Vitomir Vušak, Ottó Horváth, Diego Sampedro, Raúl Losantos, Ilijana Odak and Irena Škorić

Molecules 2024, 29(1), 201; https://doi.org/10.3390/molecules29010201 - 29 Dec 2023

Viewed by 1396

Abstract

Previous biological tests have shown that some resveratrol analogs exhibited significant antioxidative and cholinesterase inhibitory potential, as evidenced by lower IC₅₀ values compared to the established standards, resveratrol and galantamine, respectively. Photochemical transformations were made in parallel on these compounds in the [...] Read more.

Previous biological tests have shown that some resveratrol analogs exhibited significant antioxidative and cholinesterase inhibitory potential, as evidenced by lower IC₅₀ values compared to the established standards, resveratrol and galantamine, respectively. Photochemical transformations were made in parallel on these compounds in the presence of porphyrin photocatalysts in batch and microreactor, showing the significant advantage of flow photochemistry concerning productivity, selectivity, and yields. In this research, the products of photocatalysis and direct irradiation (photolysis) of resveratrol analogs were compared to elucidate how the types and ratios of the products depend on the excitation energy, to reveal the effects of the substituent on the photoinduced reactions and to rationalize experimentally and computationally the nature and ratio of the obtained products. Thus, two main paths were computed in agreement with the experimental results: isomerization with the participation of triplet state intermediates to yield the experimentally detected cis-isomers and subsequent cyclization following a pathway not available for the trans-isomers. The investigation of five model compounds confirmed the advantages of the flow photoreactor in the photochemical reactions of heterocyclic resveratrol analogs. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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11 pages, 2655 KiB

Open AccessArticle

Bio-Inspired Hydrogel–Elastomer Actuator with Bidirectional Bending and Dynamic Structural Color

by Yongqing Xia, Yaru Meng, Ronghua Yu, Ziqi Teng, Jie Zhou and Shengjie Wang

Molecules 2023, 28(19), 6752; https://doi.org/10.3390/molecules28196752 - 22 Sep 2023

Cited by 1 | Viewed by 1562

Abstract

In nature, some creatures can change their body shapes and surface colors simultaneously to respond to the external environments, which greatly inspired researchers in the development of color-tunable soft actuators. In this work, we present a facile method to prepare a smart hydrogel [...] Read more.

In nature, some creatures can change their body shapes and surface colors simultaneously to respond to the external environments, which greatly inspired researchers in the development of color-tunable soft actuators. In this work, we present a facile method to prepare a smart hydrogel actuator that can bend bidirectionally and change color simultaneously, just like an octopus. The actuator is fabricated by elastomer/hydrogel bilayer and the hydrogel layer was decorated with thermoresponsive microgels as the photonic crystal blocks. Compared with the previously reported poly(N-isopropylacrylamide) hydrogel-based bilayer hydrogel actuators, which are generally limited to one-directional deformation, the elastomer/hydrogel bilayer actuator prepared in our work exhibits unique bidirectional bending behavior in accordance with the change of structural color. The bending degrees can be changed from −360° to 270° in response to solution temperatures ranging from 20 °C to 60 °C. At the same time, the surface color changes from red to green, and then to blue, covering the full visible light spectrum. The bending direction and degree of the hydrogel actuator can easily be adjusted by tuning the layer thickness ratio of the elastomer/hydrogel or the composition of the hydrogel. The color-tunable hydrogel-elastomer actuator reported in this work can achieve both programmable deformations and color-changing highly resembling the natural actuating behaviors of creatures. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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14 pages, 5809 KiB

Open AccessArticle

In Situ Construction of Near-Infrared Response Hybrid Up-Conversion Photocatalyst for Degrading Organic Dyes and Antibiotics

by Lianqing Yu, Yankun Wang, Xinhai Su, Chong Liu, Kehui Xue, Huihua Luo, Yaping Zhang and Haifeng Zhu

Molecules 2023, 28(18), 6674; https://doi.org/10.3390/molecules28186674 - 18 Sep 2023

Viewed by 983

Abstract

Unique nonlinear optical properties for converting low-energy incident light into high-energy radiation enable up-conversion materials to be employed in photocatalytic systems. An efficient near-infrared (NIR) response photocatalyst was successfully fabricated through a facile two-step method to load BiOBr on the Nd³⁺, [...] Read more.

Unique nonlinear optical properties for converting low-energy incident light into high-energy radiation enable up-conversion materials to be employed in photocatalytic systems. An efficient near-infrared (NIR) response photocatalyst was successfully fabricated through a facile two-step method to load BiOBr on the Nd³⁺, Er³⁺@NaYF₄ (NE@NYF) up-conversion material. The NE@NYF can transform NIR into visible and UV light and promote charge–energy transfer in the semiconductor. Consequently, the as-obtained photocatalysts exhibit excellent photodegradation performance for rhodamine B dye (RhB) and tetracycline (TC) organic pollutants. About 98.9% of the RhB was decomposed within 60 min with the 20% NE@NYF-B sample, outperforming the pristine BiOBr (61.9%). In addition, the 20% NE@NYF-B composite could decompose approximately 72.7% of the organic carbon during a 10 h reaction, which was almost two-fold more than that of BiOBr. Meanwhile, a possible charge transfer mechanism is proposed based on the recombination of electron–hole pairs and reactive oxygen species. This work provides a rational hybrid structure photocatalyst for improving photocatalytic performance in the broadband spectrum and provides a new strategy for NIR light utilization. Full article

(This article belongs to the Special Issue Chemical Research on Photosensitive Materials)

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