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.

Controlled Radical Polymerization of Styrene Mediated by Xanthene-9-thione and Its Derivatives

Abstract: In our present work, a novel controlled radical polymerization system is developed based on xanthene-9-thione (XT). It was found that the radical polymerization of styrene (St) became controlled in the presence of a small amount of XT. At the early stage of the polymerization, the polymerization rate was relatively low and the as-formed polystyrene (PS) had low number-average molecular weight (Mn) and narrow polydispersity (Ð). After XT was consumed, the polymerization rate increased dramatically and the Mn of PS increased gradually with polymerization proceeding. When the polymerization of St was carried out with a proper molar ratio of initiator to XT and at an appropriate temperature, shortened slow polymerization stage and good control over Mn could be achieved. To further improve the regulating ability of XT, a series of substituent groups (-CF3, -CH(CH3)2, -N(CH3)2) were introduced onto the xanthene ring of XT, and the effects of these derivatives on the polymerization of St were investigated in detail. UV-Vis spectroscopy was carried out to monitor the concentration of XT during the polymerization and the chemical structure of the as-formed PS was fully characterized by 1HNMR and ESI-MS analysis. A possible mechanism involving the formation and evolution of the cross-termination products was proposed to interpret the observed polymerization behavior.

High-performance polyimides based on pyridine and xanthene pendant groups; synthesis, characterization, photoactivity, thermal, antibacterial, and Cr(VI) ion adsorption properties:

Abstract: A group of new polyimides (PIs) containing xanthene bulky groups and heterocyclic pyridine ring were synthesized by polycondensation reaction by using new symmetric and asymmetric diamines with ava...

Improved Synthesis of 2,2‐Arylmethylene Bis(3‐hydroxy‐5,5‐dimethyl‐2‐cyclohexene‐1‐one) and 1,8‐Dioxo‐octahydroxanthene Derivatives Catalyzed by Electrogenerated Base and Sulfuric Acid

Abstract: An efficient method has been developed for the synthesis of 1,8-dioxo-octahydroxanthene derivatives in two-step. In the first step, the electrogenerated base (EGB) catalyzed multicomponent transformation of dimedone and aromatic aldehydes in an undivided cell in the presence of sodium bromide as an electrolyte into 2,2′-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) at room temperature. In the second step, H2SO4 was employed as a dehydrating reagent for the cyclization process to give symmetrical heterocycles 1,8-dioxo-octahydroxanthene derivatives. Short reaction time, convenient work up, and using of inexpensive reagents, simple equipment, novel and eco-friendly procedure make this strategy more useful for the preparation of xanthene derivatives.

[(2-{[3',6'-Bis(ethyl-amino)-2',7'-dimethyl-3-oxospiro-[1H-isoindole-1,9'-9H-xanthen]-2-yl}eth-yl)amino-meth-yl]phenol.

Abstract: The title compound, C35H38N4O3, was prepared as a spiro­lactam ring formation of rhodamine dye for comparison with a ring-opened form. The xanthene ring system is approximately planar. The dihedral angles formed by the spiro­lactam and phenol rings with the xanthene ring system are 85.7 and 109.4°, respectively. Each of the mol­ecules in the crystal structure contains one intra­molecular O—H⋯N hydrogen bond, and they form inter­molecular N—H⋯O hydrogen-bonded chains along the [100] direction. Weak inter­molecular C—H⋯O hydrogen-bonding contacts connect the infinite chains via crystallographic inversion centres to form a two-dimensional network.