A comparative study of the photophysics of phenyl, thienyl, and chalcogen substituted rhodamine dyes.

Although rhodamine dyes have been extensively studied for a variety of applications, many details of their photophysics are not yet fully understood, including the possible presence of a charge separated electronic state lying near the optically active excited singlet state and the role of twisting substituent groups in excited-state quenching. To address this, a large library of rhodamine dyes was studied in which the chalcogen is varied from O, to S and Se and the aryl group is either absent (in the pyronin series) or is a phenyl or thienyl substituent. Through an analysis of steady-state absorption spectroscopy, electrochemistry, X-ray crystallography, and quantum mechanical calculations, we show that the lowest unoccupied molecular orbital (LUMO) energy decreases in the O → S → Se series and when a phenyl or thienyl substituent is added.

Highly Effective Dual-Function Near-Infrared (NIR) Photosensitizer for Fluorescence Imaging and Photodynamic Therapy (PDT) of Cancer.

We report herein the synthesis and biological efficacy of near-infrared (NIR), bacteriochlorin analogues: 3-(1'-butyloxy)ethyl-3-deacetyl-bacteriopurpurin-18-N-butylimide methyl ester (3) and the corresponding carboxylic acid 10. In in vitro assays, compared to its methyl ester analogue 3, the corresponding carboxylic acid derivative 10 showed higher photosensitizing efficacy. However, due to drastically different pharmacokinetics in vivo, the PS 3 (HPLC purity >99%) showed higher tumor uptake and long-term tumor cure than 10 (HPLC purity >96.

Selective photodepletion of malignant T cells in extracorporeal photopheresis with selenorhodamine photosensitizers.

Extracorporeal photopheresis (ECP) has been used successfully in the treatment of erythrodermic cutaneous T cell lymphoma (CTCL), and other T cell-mediated disorders. Not all patients obtain a significant or durable response from ECP. The design of a selective photosensitizer that spares desirable lymphocytes while targeting malignant T cells may promote cytotoxic T cell responses and improve outcomes after ECP.

Extended rhodamine photosensitizers for photodynamic therapy of cancer cells.

Extended thio- and selenorhodamines with a linear or angular fused benzo group were prepared. The absorption maxima for these compounds fell between 640 and 700nm. The extended rhodamines were evaluated for their potential as photosensitizers for photodynamic therapy in Colo-26 cells.

Selenorhodamine Dye-Sensitized Solar Cells: Influence of Structure and Surface-Anchoring Mode on Aggregation, Persistence, and Photoelectrochemical Performance.

A library of six selenorhodamine dyes (4-Se-9-Se) were synthesized, characterized, and evaluated as photosensitizers of TiO2 in dye-sensitized solar cells (DSSCs). The dyes were constructed around either a bis(julolidyl)- or bis(half-julolidyl)-modified selenoxanthylium core functionalized at the 9-position with a thienyl group bearing a carboxylic, hydroxamic, or phosphonic acid for attachment to TiO2. Absorption bands of solvated dyes 4-Se-9-Se were red-shifted relative to the dimethylamino analogues.

Selenorhodamine photosensitizers with the Texas-red core for photodynamic therapy of cancer cells.

We examined two selenorhodamines with amide and thioamide functionality at the 5-position of a 9-(2-thienyl) substituent on the selenoxanthylium analogue of the Texas-red core for their potential as photosensitizers for photodynamic therapy (PDT) in P-glycoprotein (P-gp)-expressing Colo-26 cells. These compounds were examined for their photophysical properties (absorption, fluorescence, and ability to generate singlet oxygen), for their uptake into Colo-26 cells in the absence or presence of verapamil, for their dark and phototoxicity toward Colo-26 cells, and for their co-localization with mitochondrial-specific agents in Colo-26 cells. Both compounds were extremely effective photosensitizers with values of EC50 ⩽ 4 × 10(-8)M toward Colo-26 cells with 1.

Synthesis and Properties of Heavy Chalcogen Analogues of the Texas Reds and Related Rhodamines.

Analogues of Texas red incorporating the heavy chalcogens S, Se, and Te atoms in the xanthylium core were prepared from the addition of aryl Grignard reagents to appropriate chalcogenoxanthone precursors. The xanthones were prepared via directed metalation of amide precursors, addition of dichalcogenide electrophiles, and electrophilic cyclization of the resulting chalcogenides with phosphorus oxychloride and triethylamine. The Texas red analogues incorporate two fused julolidine rings containing the rhodamine nitrogen atoms.