Synthesis and characterization of disulfonated thionines. Redox mediators for electrochemical energy conversion systems
A general synthetic strategy for the preparation of disubstituted thionines is described. A new method based on the nucleophilic coupling of a p-phenylenediamine with the synthetic equivalent of an aniline has resulted in considerable improvement, regarding particularly the suppression of byproducts (15-20% yield). The relatively low yields obtained still with the new route are an indication that thionation and ring closure of diphenylamines are difficult when electron-withdrawing groups are present. The new route has enabled the unambiguous structural characterization of two isomeric DST's known as DST-1 and DST-2 to be 4,6- and 2,6-DST, respectively. The 470-MHz /sup 1/H NMR and the UV-vis spectra for thionine, 2,6-DST, and 4,6-DST are reported. The effect of the sulfonates in the visible region has been slightly hypsochromic, the lambda/sub max/ not deviating much from that of thionine. This shift has been accounted for in terms of Dewar's rules for substituent effects in the UV-vis spectrum of odd alternate aromatic hydrocarbons. The effect in diffusion and extinction coefficients has been negligible. Disulfonation has resulted in an increased solubility in 50 mM H/sub 2/SO/sub 4/ (about 10/sup -3/ M) and less tendency to form ground-state molecular aggregates, around 10/sup -4/ M, compared to thionine, 10/sup -4/ and 10/sup -6/ M, respectively. It is concluded that it is potentially possible to design dye derivatives with improved characteristics while maintaining the best existing basic features of thionine. Derivatization of thionine with anionic substituents has permitted its solubilization in positively functionalized surfactant assemblies. This is not possible with the parent cationic thionine and can provide much higher solubilities than those observed. 33 references, 1 figure, 2 tables.
- Research Organization:
- Imperial College, London, England
- DOE Contract Number:
- AS05-82ER12088
- OSTI ID:
- 5028541
- Journal Information:
- J. Org. Chem.; (United States), Vol. 50:5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction
Photochemical conversion of solar energy. Quarterly progress report, July 1, 1976--September 30, 1976. [Iron--thionine]
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
THIONINE
SYNTHESIS
ANILINE
COUPLING
DYES
ELECTROCHEMICAL ENERGY CONVERSION
NUCLEAR MAGNETIC RESONANCE
SOLUBILITY
ULTRAVIOLET SPECTRA
AMINES
AROMATICS
CONVERSION
ENERGY CONVERSION
HETEROCYCLIC COMPOUNDS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
RESONANCE
SPECTRA
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)