title: Solvent dependence of the photophysical properties of 2-chlorothioxanthone, the principal photoproduct of chlorprothixene.
abstract: 2-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 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 TX, both properties strongly depend on the solvent polarity/hydroxylicity. The quantum yield of the triplet intermediate is very close 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.
authors.affiliation: Instituto de Tecnología Química UPV-CSIC, Universidad Politécnica de Valencia, Valencia, Spain.
authors.forename: Luis E Piñero
authors.initials: LE
authors.lastname: Santiago
authors.forename: Carmelo
authors.initials: C
authors.lastname: García
authors.forename: Virginie
authors.initials: V
authors.lastname: Lhiaubet-Vallet
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Miranda
authors.forename: Rolando
authors.initials: R
authors.lastname: Oyola
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000737:chemistry / Q000378:metabolism*; D002749:Chlorprothixene / Q000009:adverse effects / Q000737:chemistry / Q000378:metabolism*; D004735:Energy Transfer; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D055668:Photochemical Processes / Q000528:radiation effects; D010782:Photolysis / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000009:adverse effects / Q000737:chemistry / Q000378:metabolism*; D011618:Psychotic Disorders / Q000188:drug therapy; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry; D044004:Xanthones / Q000737:chemistry / Q000378:metabolism
chemical_list: D000097:Acetonitriles; D014150:Antipsychotic Agents; D017319:Photosensitizing Agents; D012997:Solvents; D044004:Xanthones; D014867:Water; D002749:Chlorprothixene; C032159:acetonitrile