A chemiluminescence study of madder lakes on paper

The photo degradation of watercolour drawings prepared with madder lake pigments on gelatine-sized paper was studied by chemiluminometry, viscometry, and colorimetry. A method of recto irradiation and verso measurement was developed to overcome absorption of the emitted photons by the paint layer. A complex relationship between paper substrate, applied chromophores and associated transition metals was observed with strong correlations between the presence of transition metals associated with the madder lakes and the degradation of the paper substrate and the applied paint layer as well as evidence of pro-oxidative activity by the chromophores in the applied paint layers. The pro-oxidant behaviour appears to be dependent on the type of transition metal present. This is the first in-depth research into the photodegradation of madder lake-based watercolours which attempts to understand the chemistry of the processes.     

基于光电双开关的单光子同步探测

提出了一种基于光电双开关进行同步测量单光子的方法.这种测量方法能够有效抑制背景光以及由背景光引起的后脉冲和死时间对单光子测量的影响,有效地减少了单光子探测中的误计数,改善了单光子测量的信噪比.同时,避免了单光子探测器通常工作在门控电压方式下产生自发光子辐射的缺点.     

Photoresponsive Covalent Organic Frameworks: Visible-Light Controlled Conversion of Porous Structures and Its Impacts

Covalent organic frameworks are a novel class of crystalline porous polymers that enable molecular design of extended polygonal skeletons to attain well-defined porous structures. However, construction of a framework that allows remote control of pores remains a challenge. Here we report a strategy that merges covalent, noncovalent, and photo chemistries to design photoresponsive frameworks with reversibly and remotely controllable pores. We developed a topology-guided multicomponent polycondensation system that integrates protruded tetrafluoroazobenzene units as photoresponsive sites on pore walls at predesigned densities, so that a series of crystalline porous frameworks with the same backbone can be constructed to develop a broad spectrum of pores ranging from mesopores to micropores. Distinct from conventional azobenzene-based systems, the tetrafluoroazobenzene frameworks are highly sensitive to visible lights to undergo high-rate isomerization. The photoisomerization exerts profound effects on pore size, shape, number, and environment, as well as molecular uptake and release, rendering the system able to convert and switch pores reversibly and remotely with visible lights. Our results open a way to a novel class of smart porous materials with pore structures and functions that are convertible and manageable with visible lights.     

Magneto recyclable,green fabricated Fe3O4 nanorods on photo responsive of textile dye degradation and identification products by LC-MS

Prior to being released towards water sources such as rivers, lakes, and groundwater, the efficient technique of removing color out textile effluents seems to have become widely used. Such contaminants are extremely difficult for traditional wastewater treatment methods to completely eliminate. This innovative development of phytonutrients uses Fe₃O₄ nanorods, that have been employed as photocatalytic to change substrate colors in the aqueous layer when exposed to light. Given prominence was adopted to incorporate phytonutrients with Fe3O4 nanorods. The degradation of the methyl violet colour has been acknowledged by the depletion of the UV light (UV) absorption edge that also originated at 581 nm. The significant colour expulsion of the Fe3O4 nanorod was proved to really be 97% after 60 min. The findings demonstrate that ecologically responsible Fe₃O₄ nanorods are immensely beneficial in the photocatalytic reaction of harmful pollutants.     

Light Triggered Pore Size Tuning in Photoswitching Covalent Triazine Frameworks for Low Energy CO2 Capture

Recently, photo switching porous materials have been widely reported for low energy costed CO₂ capture and release via simply remoted light controlling method. However, most reported photo responsive CO₂ adsorbents relied on metal organic framework (MOFs) functionalisation with photochromic moieties, and MOF adsorbents still suffered from chemically and thermally unstable issues. Thus, further metal free and highly stable organic photoresponsive adsorbents are necessary to be developed. CTFs, because of their high porosity and stability, have attracted great attention for CO₂ capture. Considering the high CO₂ uptake capacity and structural tunability of CTFs, it suggests high potential to fabricate the photoswitching CTF materials by the same functionalisation method as MOFs. Herein, the first series of photo switching CTFs were developed for low energy CO₂ capture and release. Apart from that, the CO₂ switching efficiency could be doubled either through the azobenzene numbers adjusting method or through the previously reported structural alleviation strategy. Furthermore, the pore size distribution of azobenzene functionalised PCTFs also could be tuned under UV exposure, which may contribute to the UV light induced decrease of CO₂ uptake capacity. These photoswitching CTFs represented a new kind of porous polymers for low energy costed CO₂ capture.