Xanthene

About: Xanthene is a research topic. Over the lifetime, 2132 publications have been published within this topic receiving 34803 citations. The topic is also known as: Xanthene & dibenzo[a,e]pyran.

Synthesis and identification of new thermostable polyamides containing xanthene units with antibacterial properties and relevant composite grafted with modified GO nanoparticles

Abstract: Two series of new diamine monomers containing ether linkages, polar trifluoromethyl (-CF3), and xanthene segments were prepared. In addition, relevant high-performance polyamides (PAs) were synthesized through condensation polymerization with applying diverse aliphatic and aromatic dicarboxylic acids. The structure of compounds were characterized by Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H NMR), and elemental analysis. The inherent viscosities values of the polymers were from 0.48 dL/g to 0.67 dL/g. The PAs indicated the glass transition temperatures (Tg), and 10% weight loss temperatures recorded within the range of 187–244 °C and 395–497 °C in N2 atmosphere, respectively. Polyamides showed a well antibacterial activity, with respect to the presence of xanthene segments in their structure. The polymeric nanocomposite was prepared through a combination of one of the synthesized polyamides with modified graphene oxide nanoparticles (m-GO NPs). The formation of potent chemical linkage across (m-GO) NPs and polymer chains caused photoluminescence intensity to enhance, thermal stability, and antibacterial properties of the nanocomposite than pure polyamide. The study of chromium ions adsorption from aqueous solutions was also performed at 25 °C and pH 7–8.

Preparation method and application of BiVO4-BiOBr photocatalyst

Abstract: The invention discloses a preparation method of BiVO4-BiOBr photocatalyst has a visible-light response, wherein the catalyst may be used under visible light, ultraviolet light, or sunlight The preparation method of BiVO4-BiOBr photocatalyst that is in a multilevel nest-like nanostructure and is formed by nanosheets is: heating for 8 to 24 h under an alcohol-heating temperature of 100 to 200 DEG C with pH of 5 to 10 The catalyst of the invention can decompose water-soluble organic pollutant containing chlorine and sulfur, water-soluble organic pollutant of azo, xanthene, and anthraquinone type, and biological contaminant microcystic toxins generated by harmful algal bloom

Luminescent/paramagnetic probes for detecting order in biological assemblies: transformation of luminescent probes into pi-radicals by photochemical reduction.

Abstract: The spectroscopic methods of fluorescence polarization and electron paramagnetic resonance (EPR) are used to study order and orientation of extrinsically labeled protein elements of ordered biological systems. These methods generate complementary information about the order of the system, but a consistent quantitative interpretation of the related data is complicated because the signals arise from different donors. We introduce a new method that allows us to detect both signals from the same donor. Unsubstituted xanthene dyes (eosin, erythrosin, and fluorescein) were irradiated by laser light at their absorption maximum in the presence of different reducing agents. Due to photochemical reduction, the quinoidal structure of the xanthene ring is transformed into a semiquinone, and a pi-radical is formed having a characteristic EPR signal of an unpaired electron spin with proton hyperfine interactions. A strong EPR signal is observed from the dye in solution or when specifically attached to a protein following irradiation in the presence of dithiothreitol or cysteine. We applied this technique to the study of skeletal muscle fibers. The fluorescent dye (iodoacetamido)fluorescein was covalently attached to the reactive thiol of the myosin molecule in muscle fibers. Fluorescence polarization and EPR spectroscopy were performed on the labeled fibers in rigor. Both signals indicate a highly ordered system characteristic of cross-bridges bound to actin. Our use of the same signal donor for fluorescence and EPR studies of probe order is a promising new technique for the study of order in protein elements of biological assemblies.