N-(Di)icosyl-substituted benzo[a]phenoxazinium chlorides : synthesis and evalua...

• Author(s): Naik, Sarala ; Alves, Carla M. A. ; Coutinho, Paulo J. G. ; Gonçalves, M. Sameiro T.
• Date: 2011
• Persistent ID: http://hdl.handle.net/1822/13091
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Benzo[a]phenoxazinium dyes; Membrane probes; Near-infrared labels; Nile blue; Cationic dyes
• Document Type: Article
• Language: English

Description

Five benzo[a]phenoxazinium chlorides containing alkyl chains with twenty carbon atoms on 5- or 9-positions of the tetracyclic ring were efficiently synthesised and characterised by UV/Vis/NIR spectroscopy. The absorption and emission maxima in ethanol lie in the range 627-641 nm and 645-676 nm, respectively, with quantum yields varying from 0.14 to 0.38. Preliminary photophysical studies with these fluorochromophores in zwitterionic (2,3- bis(palmitoyl-oxy)propyl-2-(trimethylammonio)ethyl phosphate, DPPC) and cationic (N,N-dimethyl-N-octadecyloctadecan-1-aminium bromide, DODAB) vesicles were carried out. The results showed that the new benzo[a]phenoxazinium derivatives are able to detect the gel to liquid-crystalline lipid phase transition through variations, either in the H-aggregation extent or in an acid-base equilibrium.