title: Ultrasound promoted synthesis of Nile Blue derivatives.
abstract: Ultrasound irradiation was used for the first time towards the synthesis of new Nile Blue related benzo[a]phenoxazinium chlorides possessing isopentylamino, (2-cyclohexylethyl)amino and phenethylamino groups at 5-position of the heterocyclic system. The efficacy of sonochemistry was investigated with some of our earlier reported synthesis of benzo[a]phenoxazinium chlorides. This newer protocol proved competent in terms of reaction times and enhanced yields. Photophysical studies carried out in ethanol, water and simulated physiological conditions, revealed that emission maxima occurred in the range 644-656 nm, with high fluorescent quantum yields. Other attractive feature exhibited by these materials includes good thermal stability. These properties might be useful in the development of fluorescent probes for biotechnology.
authors.affiliation: Centre of Physics, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal; Centre of Chemistry, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal.
authors.forename: B Rama
authors.initials: BR
authors.lastname: Raju
authors.forename: Diogo M F
authors.initials: DM
authors.lastname: Sampaio
authors.forename: M M
authors.initials: MM
authors.lastname: Silva
authors.forename: Paulo J G
authors.initials: PJ
authors.lastname: Coutinho
authors.forename: M Sameiro T
authors.initials: MS
authors.lastname: Gonçalves
mesh_terms: D000431:Ethanol / Q000737:chemistry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009930:Organic Chemicals; D010078:Oxazines / Q000138:chemical synthesis* / Q000737:chemistry*; D013696:Temperature; D014465:Ultrasonics; D014867:Water / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D009930:Organic Chemicals; D010078:Oxazines; D014867:Water; C008619:Nile Blue; D000431:Ethanol
keywords: Benzo[a]phenoxazines; NIR fluorescent probes; Nile Blue derivatives; Sonochemistry; Ultrasound irradiation