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N ‐(Di)icosyl‐Substituted Benzo[ a ]phenoxazinium Chlorides: Synthesis and Evaluation as Near‐Infrared Membrane Probes
Author(s) -
Naik Sarala,
Alves Carla M. A.,
Coutinho Paulo J. G.,
Gonçalves M. Sameiro T.
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001579
Subject(s) - chemistry , bromide , cationic polymerization , alkyl , absorption (acoustics) , absorption spectroscopy , medicinal chemistry , spectroscopy , infrared spectroscopy , vesicle , ethanol , photochemistry , membrane , organic chemistry , biochemistry , physics , quantum mechanics , acoustics
Five benzo[ a ]phenoxazinium chlorides containing alkyl chains with twenty carbon atoms at the 5‐ or 9‐positions of the tetracyclic ring were efficiently synthesised and characterised by UV/Vis and NIR spectroscopy. The absorption and emission maxima in ethanol occur 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(palmitoyloxy)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 in either the extent of H‐aggregation or in the acid–base equilibrium.