Objective(s) Theophylline, a xanthenes derivative, is still widely used as an effective bronchodilator in the management of asthmatic patients. It is used both as a prophylactic drug and to prevent acute exacerbations of asthma. The aim of study was to formulate and evaluate effect of the microencapsulation of theophylline loaded nanoparticles on the reduction of burst release. Materials and Me...

A new class of rhodamines for the application as indicator dyes in fluorescent pH sensors is presented. Their pH-sensitivity derives from photoinduced electron transfer between non-protonated amino groups and the excited chromophore which results in effective fluorescence quenching at increasing pH. The new indicator class carries a pentafluorophenyl group at the 9-position of the xanthene core...

The intensity of two-photon-excited fluorescence measured relative to the intensity of hyper-Rayleigh scattering in the same apparatus was used to determine the two-photon-excited fluorescence cross sections of the xanthene dyes Rhodamine B, Rhodamine 6G, and Fluorescein. The measured cross sections at l0 5 1064 nm are s2PF (2) 5 1.5 6 0.3 3 10250 cm4 s, 2.0 6 0.4 3 10250 cm4 s, and 1.4 6 0.3 3...

Xanthene dyes can be appended to cyclodextrins via an ester or amide bridge in order to switch the fluorescence on or off. This is made possible through the formation of nonfluorescent lactones or lactams as the fluorophore can reversibly cyclize. In this context we report a green approach for the synthesis of switchable xanthene-dye-appended cyclodextrins based on the coupling agent 4-(4,6-dim...

We individuate a photoinduced electron transfer (PeT) as a quenching mechanism affecting rhodamine B photophysics in solvent. The PeT involves an electron transfer from the carboxylate group to the xanthene ring of rhodamine B. This is finely modulated by the subtle balance of coulombic and non-classical interactions between the carboxyphenyl and xanthene rings, also mediated by the solvent. We...

The title compound, C25H29ClO4, adopts a trans conformation about the C=C double bond and the di-methyl-cyclo-hexenone rings both show an envelope conformation with the dimethyl-substituted C atom as the flap. In the mol-ecule, the hy-droxy and carbonyl groups form two intra-molecular O-H⋯O hydrogen bonds typical for xanthene derivatives. In the crystal, weak C-H⋯O hydrogen bonds link the mol-e...

Two cyclic oligoureas with 64- and 80-membered rings in which two sets of three or four rigid xanthene (X) units are connected via flexible diphenyl ether (D) units were synthesized by a stepwise fragment condensation. The compounds were characterized by (1)H NMR and ESI mass spectrometry. The structure of the cyclic octamer (XXXDXXXD) was additionally confirmed by single crystal X-ray analysis...