ABSTRACT
Indolo[3,2-a]carbazole alkaloids have drawn a growing interest in recent years owing to their potential electrical and optical properties. With 5,12-dihydroindolo[3,2-a]carbazole serving as the scaffold, two novel carbazole derivatives are synthesized in this study. Both compounds are extremely soluble in water, with solubility surpassing 7% in weight. Intriguingly, the introduction of aromatic substituents contributed to drastically reduce the π-stacking ability of carbazole derivatives, while the presence of the sulfonic acid groups enables the resulting carbazoles remarkably soluble in water, allowing them to be used as especially efficient water-soluble PIs in conjunction with co-initiators, i.e., triethanolamine and the iodonium salt, respectively, employed as electron donor and acceptor. Surprisingly, multi-component photoinitiating systems based on these synthesized carbazole derivatives could be used for the in situ preparation of hydrogels containing silver nanoparticles via laser write procedure with a light emitting diode (LED)@405 nm as light source, and the produced hydrogels display antibacterial activity against Escherichia coli.
Subject(s)
Hydrogels , Metal Nanoparticles , Water , Silver , CarbazolesABSTRACT
Currently, increasing attention has been focused on light-emitting diodes (LEDs)-induced photopolymerization. The common LEDs (e.g., LED at 365 nm and LED at 405 nm) possess narrow emission bands. Due to their light absorption properties, most commercial photoinitiators are sensitive to UV light and cannot be optimally activated under visible LED irradiation. Although many photoinitiators have been designed for LED-induced free radical polymerization and cationic polymerization, there is still the issue of the mating between photoinitiators and LEDs. Therefore, the development of novel photoinitiators, which could be applied under LED irradiation, is significant. Many photoinitiating systems have been reported in the past decade. In this review, some recently developed photoinitiators used in LED-induced photopolymerization, mainly in the past 5 years, are summarized and categorized as Type â photoinitiators, Type â ¡ photoinitiators, and dye-based photoinitiating systems. In addition, their light absorption properties and photoinitiation efficiencies are discussed.
ABSTRACT
Au@g-C3N4/SnS yolk-shell Z-scheme photocatalysts are fabricated by a simple template-assisted strategy. The l-cysteine can offer the amine groups and meanwhile anchor on the surface of g-C3N4 during solvothermal reaction and thus contributes greatly to the enhanced carbon dioxide adsorption capability. This Z-scheme photocatalytic reduction mechanism of Au@g-C3N4/SnS performs valuable functions in the reaction, leading to CH4 generation much earlier and higher concentration than that of Au@g-C3N4. Meanwhile, the unique yolk-shell structure can make the light bounce back and forth in the cavity and thus enhances the availability ratio of light. The application of small amount of noble metal cocatalysts and the large Brunauer-Emmett-Teller surface areas are also benefited for the enhanced photocatalytic activities. Hence, this novel material exhibits a distinguished reduction performance for CO2 reduction under visible light. The highest yields of CH4 (3.8 µmol g-1), CH3OH (5.3 µmol g-1), and CO (17.1 µmol g-1) can be obtained for the sample of Au@g-C3N4/SnS (SnS 41.5%), which is higher than other latest reported g-C3N4-based photocatalysts for CO2 photoreduction including coupled with semiconductors and noble metal cocatalysts. This strategy might represent a novel way for the effective transition of CO2 to clean fuels and can also be enormous feasible utilization in the photocatalytic field.
