photochromic materials
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2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Nathan Man-Wai Wu ◽  
Maggie Ng ◽  
Vivian Wing-Wah Yam

AbstractPhotochromic materials have drawn growing attention because using light as a stimulus has been regarded as a convenient and environmental-friendly way to control properties of smart materials. While photoresponsive systems that are capable of showing multiple-state photochromism are attractive, the development of materials with such capabilities has remained a challenging task. Here we show that a benzo[b]phosphole thieno[3,2‑b]phosphole-containing alkynylgold(I) complex features multiple photoinduced color changes, in which the gold(I) metal center plays an important role in separating two photoactive units that leads to the suppression of intramolecular quenching processes of the excited states. More importantly, the exclusive photochemical reactivity of the thieno[3,2‑b]phosphole moiety of the gold(I) complex can be initiated upon photoirradiation of visible light. Stepwise photochromism of the gold(I) complex has been made possible, offering an effective strategy for the construction of multiple-state photochromic materials with multiple photocontrolled states to enhance the storage capacity of potential optical memory devices.


Author(s):  
Guofeng Zhang ◽  
Linqi Huang ◽  
Fuchao Yang

Photochromic materials with anti-water properties have impressed practical values, but their applications are severely hindered by poor stability and slow colour-switching rate. Inspired by the superhydrophobicity of lotus leaf and...


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3192
Author(s):  
Hao Xu ◽  
Liangjing Zhang ◽  
Aiwu Wang ◽  
Juan Hou ◽  
Xuhong Guo

Photochromic materials have attracted increasing attention. Here, we report a novel photo-reversible color switching system based on oxygen-vacancy-engineered MoOx nanostructures with water/N-methyl-2-pyrrolidone (NMP) as solvents. In this work, the system rapidly changed from colorless to blue under UV irradiation (360–400 nm) and slowly recovered its colorless state under visible light irradiation. The obtained oxygen vacancy-engineered MoOx nanostructures exhibited good repeatability, chemical stability, and cycling stability. Upon UV light irradiation, H+ was intercalated into layered MoOx nanostructures and the Mo6+ concentration in the HxMoOx decreased, while the Mo5+ concentration increased and increased oxygen vacancies changed the color to blue. Then, it recovered its original color slowly without UV light irradiation. What is more, the system was highly sensitive to UV light even on cloudy days. Compared with other reported photochromic materials, the system in this study has the advantage of facile preparation and provides new insights for the development of photochromic materials without dyes.


Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3049
Author(s):  
Yuhua Zhang ◽  
Xi Zhang ◽  
Yurong Yan ◽  
Zhonghua Chen

Photochromic materials are interesting materials because of their color-changing property under UV light and visible light irradiation. However, they are vulnerable to many factors, such as pH oxygen, ion, solvent, etc. because of the unsaturated bonds existing on the photochromic molecular. Microencapsulation of the photochromic materials can separate them from the surroundings. Here, photochromic microcapsules using 3,3-Diphenyl-3H-naphtho[2,1-b] pyran (NP)/solution as core and polyurea as shell via interfacial polymerization were prepared, and bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate (HALS 770) was used as photostabilizer. Fourier transform infrared spectroscopy (FTIR), a laser particle size analyzer, a scanning electron microscope (SEM), a thermogravimetric analyzer and an ultraviolet-visible spectrophotometer were used for characterization. The results showed that the microcapsules had a uniform particle size of about 0.56 μm when the percentage of the oil phase (core) in the emulsion was less than 15%, the addition amount of the emulsifier was 0.4%, and the stirring rate was 1800r/min. The microcapsules showed better performance in thermal stability when the core/shell ratio was 1:1. The photostabilizer had little impact on the color-changing property of the microcapsule, but it could protect the microcapsules from UV light radiation aging.


2021 ◽  
Author(s):  
Sheetal Marganakop ◽  
Pramod Kattimani ◽  
Sudha Belgur Satyanarayana ◽  
Ravindra Kamble

Microwave chemistry involves the application of microwave radiation to chemical reactions and has played an important role in organic synthesis. Functional dyes are those with hi-tech applications and this chapter attempts to provide an overview of the recent developments in microwave-assisted synthesis of functional dyes. Emphasis has been paid to the microwave-assisted synthesis of dye molecules which are useful in hi-tech applications such as optoelectronics (dye-sensitized solar cells), photochromic materials, liquid crystal displays, newer emissive displays (organic-light emitting devices), electronic materials (organic semiconductors), imaging technologies (electrophotography viz., photocopying and laser printing), biomedical applications (fluorescent sensors and anticancer treatment such as photodynamic therapy). In this chapter, the advantages of microwaves as a source of energy for heating synthesis reactions have been demonstrated. The use of microwaves to functional dyes is a paradigm shift in dye chemistry. Until recently most academic laboratories did not practice this technique in the synthesis of such functional dyes but many reports are being appeared in the journals of high repute.


2021 ◽  
Vol 8 ◽  
Author(s):  
Frederico B. De Sousa ◽  
Frank Alexis ◽  
Silvia Giordani

2021 ◽  
pp. 2100669
Author(s):  
Zetian Yang ◽  
Jiaren Du ◽  
Lisa I. D. J. Martin ◽  
Ang Feng ◽  
Ewoud Cosaert ◽  
...  

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