Solvent Dependence of the Photophysical Properties of 2‐Chlorothioxanthone, the Principal Photoproduct of Chlorprothixene

Abstract

Abstract2-Chlorothioxanthone (CTX) is used as photoinitiator for the reticulation of synthetic resins and for the preparation of pharmaceuticals. It was previously determined that CTX is the primary photoproduct of z-chlorprothixene (CPTX) when irradiated at 313 nm and is formed in an autocatalyzed reaction through an energy transfer mechanism [Piñero, L. E. et. al. (2009) Photochem. Photobiol. 85, 895-900]. In this work, the photophysical properties of CTX were measured in acetonitrile/water solutions to determine if their magnitude can affect the side-effects of CPTX. The results show that CTX has higher absorption coefficients in the visible region (400-420 nm) and higher triplet quantum yields than its parent compound. Similar to for TX, both properties strongly depend on the solvent polarity/hydroxylicity. The quantum yield of the triplet intermediate is very closed to the value of the phenothiazine triplets. The phenothiazines are the most phototoxic antidepressants. Therefore, given the appropriate microenvironment, the photosensitization side-effects of CPTX can be intensified on the production of CTX.

Structure‐Dependent cis/trans Isomerization of Tetraphenylethene Derivatives: Consequences for Aggregation‐Induced Emission

“…[1] Fore xample, trans-tamoxifen is ap otent estrogen receptor antagonist, which is used for the treatment of breast cancer, whereas cis-tamoxifen is af ull estrogen agonist. We have nowobserved the tautomerization-induced isomerization of ah ydroxy-substituted derivative,T PETH-OH, under acidic but not under basic conditions.Replacing the proton of the hydroxy group in TPETH-OH with an alkyl group leads to the formation of TPETH-MAL, for whicht he pure cis and trans isomers were obtained and characterized by HPLC analysis and NMR spectroscopy.…”

“…[1] Fore xample, trans-tamoxifen is ap otent estrogen receptor antagonist, which is used for the treatment of breast cancer, whereas cis-tamoxifen is af ull estrogen agonist. Geometric cis and trans isomers have been reported to differ in their pharmacodynamic and pharmacokinetic properties.…”

Structure‐Dependent cis/trans Isomerization of Tetraphenylethene Derivatives: Consequences for Aggregation‐Induced Emission

“…Geometric cis and trans isomers have been reported to differ in their pharmacodynamic and pharmacokinetic properties. [1] Fore xample, trans-tamoxifen is ap otent estrogen receptor antagonist, which is used for the treatment of breast cancer, whereas cis-tamoxifen is af ull estrogen agonist. [2] Carbon-carbon double bonds are also built-in elements of fluorescent dyes whose cis and trans isomers display different optical properties.…”

Síntesis y estudio fotofísico y fotoquímico de fármacos neurolépticos.

“…El tiempo de vida de fluorescencia de 1 CTX* se midió en soluciones de MeCN/Agua para entender el efecto del microambiente en su dinámica de relajación (Fig. 3.38) [92] . Este parámetro tiene un comportamiento monoexponencial (Fig.…”

“…[108] Esta tendencia se correlaciona bien con la de los valores relativos experimentales (kJ/mol): S 1 = 299 y T 1 = 270. [92,110] Este comportamiento es similar al del estado singlete excitado de benzofenona (BP), cuyo estado excitado T 2 ( 3 np*) tiene una energía mayor al S 1 ( 1 pp*) en disolventes altamente polares e hidroxílicos. [111] Esto induce un ISC lento y, por consiguiente, aumenta la desactivación por fluorescencia.…”