Self-Assembly, Chromic Properties, and Nanostructure Formation of Tetrathiafulvalene-Fused Dodecadehydro[18]annulenes

Abstract

Abstract Multifunctional dodecadehydrotris(tetrathiafulvaleno)[18]annulenes 1b–1d, which have six peripheral butylthio substituents or six ester substituents, were synthesized together with the corresponding [12]annulene 2c. The [18]annulenes 1b–1d easily formed stacked dimers and higher oligomers in solution via nanoscopic phase separation among the π-frame, ester or alkylthio substituents, and inner sphere to show solvatochromism and thermochromism. Furthermore, the strong self-aggregation of their oxidized radical cations in solution resulted in electrochromism depending on the formation of various types of mixed-valence states and π-dimers. Interestingly, self-aggregation of the [18]annulenes 1b–1d in amphiphilic media such as THF–H2O either produced fibrous structures in the case of the hexabutylthio derivative 1b and hexabutyl ester 1c or resulted in the temperature hysteresis of the color, UV–vis absorptions, and 1H NMR signals obtained in solution in the case of the hexaoctyl ester 1d which forms no fiber and precipitate under similar conditions. It is noted that fibers of the hexabutyl ester 1c can be aligned in a magnetic field using the large diamagnetic response of the [18]annulene frame for the driving force. A small difference in the substituents of 1b–1d causes a remarkable change in either their solvato- and electrochromism or nanostructure formation of 1b–1d based on the self-assembling nature both in solution and in the solid state.