Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

We present a new series of photochromic 1,2-bis(2-ethylbenzo[b]thiophen-3-yl)perfluorocyclopentenes with an oxidized benzothiophene core (O) or a nonoxidized one, decorated with mono- (Th1) and bithiophene (Th2) units attached to positions 6 and 6′ (Sy = symmetric) or only to position 6 (As = asymmetric). “Oxidized” compounds have highly fluorescent closed forms emitting in the visible region (yellow to red). The dyes with nonoxidized benzothiophenes possess fluorescent open forms with rather low emission efficiency. The photoswitching kinetics was studied at several wavelengths with UV and visible light. New diarylethenes underwent ring-closure reactions by irradiation with UV light (365 nm, 405 nm), and the reversible ring-opening by irradiation with visible light (470 nm, 530 nm). The on-switching of fluorescence due to the ring-closure reaction was observed also with visible light of 470 nm (to an extent of 10% for compound SyOTh 1 ) and attributed to the Urbach tail effect. Due to a high degree of fluorescence modulation (>270), good fatigue resistance and large fluorescence quantum yield, compound SyOTh 1 emerged as a candidate for single-molecule based super-resolution fluorescence microscopy.

Download Full-text

Enhanced Photocatalytic Activity of N/Li2MoO4 Co-doped TiO2 Nanoparticles under Visible Light

Applied Science and Engineering Progress ◽

10.14416/j.asep.2021.10.007 ◽

2021 ◽

Author(s):

Jutarat Kwakkaew ◽

Matthana Khangkhamano ◽

Rungrote Kokoo ◽

Weerachai Sangchay

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Tio2 Nanoparticles ◽

Photocatalytic Oxidation ◽

Uv Light ◽

Visible Region ◽

Strong Light ◽

Doped Tio2 ◽

Vis Spectroscopy ◽

Wide Range

TiO2-based nanomaterials have been extensively synthesized and used in a wide range of photocatalytic applications. The photocatalytic oxidation process, however, is only activated by irradiation with ultraviolet (UV) light which limits its indoor applications. Herein, to improve such limitations, N/Li2MoO4-doped TiO2 nanoparticles were prepared via sol-gel method. Li2MoO4 concentration was varied. The catalysts were characterized by XRD, XPS, FE-SEM, and UV-Vis spectroscopy. As-synthesized N/Li2MoO4-doped TiO2 catalysts exhibited their crystal sizes of as fine as 20 nm in diameter whereas that of the pure TiO2 was about 35 nm. The absorption ranges of the N/ Li2MoO4-doped catalysts were relocated from UV region toward visible light region. The catalyst with 1 mol% Li2MoO4 offered the highest degradation rate of methylene blue (MB) solution upon visible light irradiation. Its fine crystal size, narrow band gap energy (2.82 eV), high defect concentration, and strong light absorption in visible region are responsible for the enhanced photocatalytic activity of the 1 mol% Li2MoO4.

Download Full-text

ZnFe2O4 Doped TiO2 Photocatalyst Synthesis and Characterization with Effect of Different Coupling Ratios on Band Gap

Journal of the chemical society of pakistan ◽

10.52568/000969/jcsp/43.06.2021 ◽

2021 ◽

Vol 43 (6) ◽

pp. 736-736

Author(s):

Farukh Iqbal Farukh Iqbal ◽

Saad Nadeem Saad Nadeem ◽

Kamran Zakaria and Bawadi Abdullah Kamran Zakaria and Bawadi Abdullah

Keyword(s):

Visible Light ◽

Band Gap ◽

Uv Light ◽

Sol Gel ◽

Visible Region ◽

Xrd Analysis ◽

Phase Identification ◽

Coupling Ratio ◽

Color Mapping ◽

Visible Light Driven

In this work the effect of different coupling ratios of ZnFe2O4 and TiO2 on the band gap was investigated, to convert TiO2 as a visible light driven photocatalyst ZnFe2O4. In this work, ZnFe2O4 was synthesized utilizing sol-gel technique and calcining under normal atmosphere at 900 and#176;C. Thereafter, ZnFe2O4 was coupled with TiO2 by mixing in 50 ml water in three different coupling w/w ratios (1:1, 1:2 and 2:1) followed by the calcination of coupled catalyst under nitrogen environment at 500 and#176;C. XRD, XPS, FESEM-EDS imaging, TGA, UV-Vis, and FTIR were performed to characterize the catalyst. Crystal phase identification could be confirmed through XRD analysis with homogenous distribution of metal constituents through color mapping and surface charge transitions from XPS analysis for a better electron hole generation. Thermogravimetric analysis (TGA) confirmed that the pure ZnFe2O4 obtained at 900 and#176;C, while FTIR verified the presence of desired functional group in ZnFe2O4. Moreover, Fourier Transformation Infrared Spectroscopy (FTIR) illustrated two major peaks and no extra major impurity was detected. ZnFe2O4 is visible light driven photocatalyst and TiO2 can work only under UV light. So, the effect of different coupling ratios of ZnFe2O4 with TiO2 was examined by UV-Vis characterization. The band gap is given by 1:1 was 2.8, 2:1 was 3.17 and 1:2 was 3.02. It was observed that the most optimum coupling ratio is 1:1 and the band-gap fall under visible region. The findings of this work could be supportive significantly for the selection of suitable coupling ratio to convert UV-driven photocatalyst into visible region active photocatalyst.

Download Full-text

Photocatalytic Degradation of Carbaryl over Novel MWNT-TiO2 Nanocomposite under Visible Light Irradiation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.476 ◽

2011 ◽

Vol 233-235 ◽

pp. 476-480

Author(s):

Ke Dai ◽

Hai Bo Chen ◽

Xu Li ◽

Hao Chen ◽

Qiao Yun Huang

Keyword(s):

Visible Light ◽

Visible Light Irradiation ◽

Ring Opening ◽

Uv Light ◽

Light Irradiation ◽

Photodegradation Efficiency ◽

Uv Light Irradiation ◽

Ring Opening Reaction ◽

Visible Light Driven ◽

Direct Growth

The MWNT-TiO2nanocomposite was synthesized via direct growth of TiO2nanoparticles on the surface of the functionalized MWNTs by the hydrothermal treatment and utilized as the photocatalyst in the carbaryl degradation under both visible light and UV light irradiation. Visible-light-driven activity and enhanced UV-light-driven activity are both achieved as the composite MWNTs with TiO2can efficiently enhance the light absorption and charge separation and then photocatalytic activity. The photodegradation efficiency of carbaryl was examined by HPLC and IC techniques, which demonstrates that carbaryl can be readily degraded under visible light irradiation. Based on the obtained experimental results, assisted with the computer simulation of carbaryl molecule on PM3 level, it is presumed that the degradation of carbaryl starts with the break of N21-C23 and C19-N21 bonds and ends in the generation of naphthalen-1-ol before the ring-opening reaction.

Download Full-text

Cu2O–TiO2 Composite for Photocatalytic Degradation of Benzene and its derivatives Using Visible Light

Current Nanoscience ◽

10.2174/1573413717666210127102749 ◽

2021 ◽

Vol 17 ◽

Author(s):

Satya Vijaya Kumar Nune ◽

Ravi Kumar Golimidi

Keyword(s):

Visible Light ◽

Photocatalytic Degradation ◽

Band Gap ◽

Tio2 Nanoparticles ◽

Uv Light ◽

High Surface ◽

High Surface Area ◽

Visible Region ◽

Copper Ion ◽

Visible Light Active

Background: Heterostructured nanocomposites have gained huge attention for their catalytic properties lately. A wide array of different visible-light-active photocatalysts (VLAPs) have been extensively studied of the past couple of years to fine tune the band gap of various stable semiconductors. Objective: The current investigation reports the sensitization of TiO2 nanoparticles with nano sized cuprous oxide, a wellstudied p-type semiconductor, which has a relatively narrow band gap ranging between 2.1 eV & 2.6 eV, to obtain a visible light active photocatalyst. Methods: visible-light-active Cu2O–TiO2 nanocomposite synthesized using solvo-thermal technique. The nanocomposite’s structure and size properties were studied using powder diffraction (XRD), electron microscopy (FESEM and HRTEM). Cu2O–TiO2 nanocomposite was tested on benzene, toluene and chlorobenzene in contaminated water, under UV and under visible light, for effective implementation in photocatalytic degradation of volatile organic contaminants. Results: The said nanocomposite was crystalline and found to be 40–50 nm in size. No apparent change in the crystal lattice of TiO2 was observed due to the introduction of copper ion, and the nanocomposite also retained high surface area of 76.28 m2 /g. The efficiency of the Cu2O-TiO2 nanoparticles degradation is studied both under UV light and under visible. Cu2O-TiO2 nanoparticles have achieved 97 – 99% degradation of benzene, 92 – 97% degradation of toluene and 95 – 98% degradation of chlorobenzene in water. Conclusion: The said Cu2O–TiO2 nanocomposite is photo-active and showed an overall 95% degradation within 2 hours of treatment under the visible region.

Download Full-text

1992 Merck–Frosst Award Lecture Orbital symmetry and the photochemistry of cyclobutene

Canadian Journal of Chemistry ◽

10.1139/v93-021 ◽

1993 ◽

Vol 71 (2) ◽

pp. 147-155 ◽

Cited By ~ 14

Author(s):

William J. Leigh

Keyword(s):

Ring Opening ◽

Rydberg State ◽

Uv Light ◽

Light Sources ◽

Unusual Behavior ◽

Orbital Symmetry ◽

Direct Photolysis ◽

High Degree ◽

Π State ◽

Theoretical Results

Direct photolysis of alkyl-substituted cyclobutene derivatives in solution with monochromatic far-UV light sources results in competing ring opening to the corresponding substituted 1,3-butadiene derivatives and fragmentation to the corresponding alkene and alkyne via formal [2 + 2] cycloreversion. The excited states leading to the two types of products have been identified. Cycloreversion occurs stereospecifically and arises as a result of excitation of the π,R(3s) Rydberg state, which is of comparable energy to the π,π* state in alkylcyclobutenes. In spite of its stereospecificity, the reaction is nonconcerted; evidence is presented to suggest that it occurs by a mechanism involving [1,2] migration (ring contraction) to yield a cyclopropylcarbene intermediate, which then fragments to yield the alkyne and alkene. The stereochemistry at C3 and C4 in the starting cyclobutene is retained in the alkene produced in the reaction. Ring opening proceeds nonstereoselectively (from the π,π* singlet state) in well over a dozen systems that have been investigated, and possible mechanisms to account for this are discussed. It is proposed that orbital symmetry plays a role in the reaction, but only in the early stages of ring opening. Bicyclic cyclobutene derivatives in which the cyclobutene double bond is located across the [0] bridge undergo ring opening with a high degree of disrotatory stereoselectivity. Possible reasons for this unusual behavior are discussed in light of recent ab initio theoretical results.

Download Full-text

Direct Sunlight Active Sm3+ Doped TiO2 Photocatalyst

Materials Science Forum ◽

10.4028/www.scientific.net/msf.855.33 ◽

2016 ◽

Vol 855 ◽

pp. 33-44 ◽

Cited By ~ 8

Author(s):

Binu Naufal ◽

P.K. Jaseela ◽

Pradeepan Periyat

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Visible Light Irradiation ◽

Uv Light ◽

Sol Gel ◽

Visible Region ◽

Light Irradiation ◽

Significant Shift ◽

Sem Images ◽

Blue Solution

TiO2 and Sm3+ doped TiO2 nanocrystalline has been successfully synthesized by a modified sol-gel method. As synthesized samples of TiO2 and Sm3+ doped TiO2 were calcined at 300, 500, 700 and 800OC and characterized by various techniques such as XRD, UV/Vis Reflectance spectroscopy, FTIR, SEM-EDS and TEM. The crystallite size of Sm3+ doped TiO2 at all calcination temperature is lower than that of TiO2 due the doping Sm3+ ion and thereby induced more nanobehavior. FTIR spectroscopy confirmed the presence of Ti-O and Ti-O-Ti bond in TiO2, in Sm3+ doped TiO2 along with Ti-O and Ti-O-Ti, the presence Sm-O and Ti-O-Sm bonds are confirmed. Diffuse reflectance spectra showed that the Sm3+ doped TiO2 have a significant shift to longer wavelengths and an extension of the absorption in the visible region compared to the TiO2. SEM images confirmed that the particles are agglomerated and the particle size was decreased in the Sm3+ doped TiO2 in comparison with the TiO2. EDS analysis showed the presence of Sm3+ ion present in the lattice of TiO2 in doped sample. Finally the photocatalytic activity of TiO2 and Sm3+ doped TiO2 at various calcinations temperatures was investigated by the degradation of methylene blue solution under UV light and visible light. Doping with the samarium ions significantly enhanced the overall photocatalytic activity for MB degradation under both UV and visible light irradiation. The results showed that the Sm3+ doped TiO2 sample calcined at 700 OC shows the highest photocatalytic activity under UV light and visible light irradiation.

Download Full-text

Visible Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones

10.26434/chemrxiv.11467845.v1 ◽

2019 ◽

Author(s):

Marharyta V. Laktsevich-Iskryk ◽

Nastassia A. Varabyeva ◽

Volha V. Kazlova ◽

Vladimir N. Zhabinskii ◽

Vladimir A. Khripach ◽

...

Keyword(s):

Visible Light ◽

Functional Groups ◽

Ring Opening ◽

Radical Intermediates ◽

Reaction Proceeds

In this article, we report a photocatalytic protocol for the isomerization of 1,2-disubstituted cyclopropanols to linear ketones. The reaction proceeds <i>via</i> radical intermediates and tolerates various functional groups.

Download Full-text

Visible Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones

10.26434/chemrxiv.11467845 ◽

2019 ◽

Author(s):

Marharyta V. Laktsevich-Iskryk ◽

Nastassia A. Varabyeva ◽

Volha V. Kazlova ◽

Vladimir N. Zhabinskii ◽

Vladimir A. Khripach ◽

...

Keyword(s):

Visible Light ◽

Functional Groups ◽

Ring Opening ◽

Radical Intermediates ◽

Reaction Proceeds

Download Full-text

Visible-Light Activated [2+2] Photocycloaddition Reaction Enabled Identification of Carbon-Carbon Double Bonds Position Isomerism in Structural Lipidomics

10.26434/chemrxiv.11813475 ◽

2020 ◽

Author(s):

Guifang Feng ◽

Yanhong Hao ◽

Liang Wu ◽

Suming Chen

Keyword(s):

Visible Light ◽

Uv Light ◽

Practical Importance ◽

Side Reactions ◽

Potential Health ◽

Fundamental Interest ◽

Unsaturated Lipids ◽

Health Damage ◽

Global Identification ◽

Polyunsaturated Lipids

The photocycloaddition of olefins with carbonyls is of fundamental interest and practical importance in C=C bond location in unsaturated lipids. However, the traditional UV light activated [2+2] photocycloaddition reaction suffers side reactions and potential health damage. Here, we reported the first example of visible-light activated [2+2] photocycloaddition of anthraquinone with unsaturated lipids. This reaction showed great capability for locating the C=C bonds in various kinds of monounsaturated and polyunsaturated lipids by combining with tandem mass spectrometry (MS), such as fatty acids, phospholipids and glycerides. Based on this developed reaction, a workflow with liquid chromatography tandem MS method was developed for the global identification of unsaturated lipids in human serum, and 86 of monounsaturated and complicated polyunsaturated lipids were identified with definitive positions of C=C bonds. This approach provides new insights both on the photocycloaddition reactions and the structural lipidomics.

Download Full-text

Green Synthesis of ZnO/Dy/NiO Heterostructures for Enhanced Photocatalytic Applications

Journal of Photocatalysis ◽

10.2174/2665976x01666200214125616 ◽

2020 ◽

Vol 1 (1) ◽

pp. 30-36

Author(s):

Shubha Jayachamarajapura Pranesh ◽

Diwya Lanka

Keyword(s):

Visible Light ◽

Uv Light ◽

Combustion Method ◽

Hybrid Nanocomposites ◽

Synthetic Dyes ◽

Hybrid Nanostructure ◽

Wide Range ◽

Visible Light Active ◽

Textile Industries ◽

Photocatalytic Applications

Background: Textile industries discharge harmful synthetic dyes to nearby water sources. These colour effluents should be treated before discharge to reduce the toxicity caused by synthetic colours. Objective: To synthesize visible light active superstructures to reduce water pollution caused by textile industries. Methods: We have successfully synthesized ZnO/Dy/NiO hybrid nanocomposites using waste curd as fuel by a simple combustion method. The obtained material was able to reduce recombination and enhanced the photocatalytic degradation of organic pollutants. The as-synthesized material was characterized by XRD, absorption spectroscopy, FESEM, EDAX, etc. The obtained hybrid nanostructure was used as a photocatalyst for the degradation of methylene blue under sunlight, UV light as well as in dark. Comparative experiments were carried out with a variation of catalytic load, pH, dye concentrations, etc. for a better understanding of the performance of the catalyst at various conditions. Results and Conclusion: The ternary compound shows wide range of absorption by expanding absorption band both in UV and visible regions. ZnO/Dy/NiO hybrid nanocomposites performed well and showed uniqueness in the activity uder visible light.

Download Full-text