Curcumin degradation kinetics in micellar solutions: Enhanced stability in the presence of cationic surfactants

Electronic absorption spectroscopy was used to measure the molecular association of copper phthalocyanine tetrasulfonate in micellar solutions, a microemulsion made with cationic surfactant, and homogeneous solvents. Analysis of absorbance versus concentration data using a multiple-aggregation model and non-linear regression analysis gave values of association constants, molar absorptivities and estimates of average aggregation number. Microemulsions and aqueous micellar solutions made with alkylammonium surfactants inhibited aggregation, probably because of interactions between the phthalocyanine sulfonate groups and the cationic surfactant head groups at interfacial surfaces. Similar aggregation behavior was observed previously in multiple-bilayer films of cationic surfactants. Water and aqueous solutions containing tetraethylammonium bromide or anionic SDS micelles provide environments facilitating extensive aggregation of Cu II PcTS 4−. The major species are dimers in water and acetonitrile/water, but the formation of higher aggregates is promoted by addition of SDS or TEAB. Aprotic organic solvents provide environments intermediate between these two extremes, giving relatively large aggregation numbers (i.e. five to seven) but smaller association constants than aqueous media not containing cationic surfactants.

Download Full-text

Solvatochromism in aqueous micellar solutions: effects of the molecular structures of solvatochromic probes and cationic surfactants

Physical Chemistry Chemical Physics ◽

10.1039/a809244c ◽

1999 ◽

Vol 1 (8) ◽

pp. 1957-1964 ◽

Cited By ~ 31

Author(s):

Luzia P. Novaki ◽

Omar A. El Seoud

Keyword(s):

Cationic Surfactants ◽

Molecular Structures ◽

Micellar Solutions ◽

Solvatochromic Probes ◽

Aqueous Micellar Solutions

Download Full-text

Photolysis of 1,2-dihydroquinolines in micellar solutions of anionic and cationic surfactants

Kinetics and Catalysis ◽

10.1134/s0023158408020080 ◽

2008 ◽

Vol 49 (2) ◽

pp. 218-225 ◽

Cited By ~ 3

Author(s):

T. D. Nekipelova

Keyword(s):

Cationic Surfactants ◽

Micellar Solutions ◽

Anionic And Cationic Surfactants

Download Full-text

Behavior of 1,1,1-Trifluoroacetylacetone and 1,1,1-Trifluoro-3-(2-thenoyl)acetone in Aqueous Micellar Solutions of the Cationic Surfactants Tetradecyltrimethylammonium Bromide and Tetradecyltrimethylammonium Chloride

Langmuir ◽

10.1021/la000800n ◽

2000 ◽

Vol 16 (22) ◽

pp. 8438-8446 ◽

Cited By ~ 10

Author(s):

Emilia Iglesias

Keyword(s):

Cationic Surfactants ◽

Micellar Solutions ◽

Tetradecyltrimethylammonium Bromide ◽

Aqueous Micellar Solutions

Download Full-text

Kinetic and spectroscopic investigations of aqueous micelles of cationic surfactants

Open Chemistry ◽

10.2478/s11532-010-0108-x ◽

2010 ◽

Vol 8 (6) ◽

pp. 1318-1322 ◽

Cited By ~ 2

Author(s):

Luciana Luchetti

Keyword(s):

Charge Transfer ◽

Cationic Surfactants ◽

Gemini Surfactants ◽

Intramolecular Charge Transfer ◽

Kinetic Investigation ◽

Micellar Solutions ◽

Sn2 Reactions ◽

Probe Site ◽

Aqueous Micelles ◽

Aqueous Micellar Solutions

AbstractThe aqueous micellar solutions of monocationic surfactants N-hexadecyl-N,N,N-trimethylammonium bromide (CTABr), N-hexadecyl-N,N,N-trimethylammonium nitrate (CTANO3), N,N,N-tributyl-N-hexadecylammonium bromide (CTBABr) and gemini surfactants 1,4-bis(N-hexadecyl-N,N-dimethylammonium)ethane dibromide (C-E-C2Br), 1,4-bis(N-hexadecyl-N,N-dimethylammonium)propane dibromide (C-P-C2Br), and 1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (C-B-C2Br) were studied with a solvatochromic probe, 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate, better known as Reichard’s ET-30 dye. The local polarity at the probe site (ET) was calculated from the wavelength maximum of the lowest-energy intramolecular charge-transfer ϖ-ϖ* absorption band of ET-30. The results were compared with a kinetic investigation of the cyclization of 2-(3-bromopropyloxy)phenoxide (PhBr7) in micelles; this reaction is a model for SN2 reactions and it depends on medium polarity.

Download Full-text