ISSN:
1573-9171
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract 2,2′-Bis[2-(4-dimethylaminophenyl)-5-trimethylammonio-1,3-indandione] diperchlorate and 2,2′-bis[2-(4-dimethylaminophenyl)-5-(2,4,6-triphenylpyridinio)-1,3-indandione] diperchlorate have very definite thermochromic and mechanochromic properties, owing to reversible dissociation into free radicals. The rupture energy of the central bond C2-C2′ in 5-substituted 2,2′'-bis[2-(4-dimethylaminophenyl)-1,3-indandiones] in acetonitrile is 63–75 kJ/mole; in the dimer with the bulky 5-(2,4,6-triphenylpyridinium) substituent, the rupture energy is 51 kJ/mole. The equilibrium constants follow the Hammett equation (p=1.53, acetonitrile, 293 K). Radicals with onium substituents are thermodynamically the most stable of the arylindandionyl radicals that are thus far known, owing to the significant contribution of electrostatic interactions.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00957842
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