Cholesterol-substituted Tetrathiafulvalene (TTF) Compound: Formation of Organogel and Supramolecular Chirality

Carbon-Nanotube-Mediated Electrochemical Transition in a Redox-Active Supramolecular Hydrogel Derived from Viologen and an l-Alanine-Based Amphiphile

A two-component hydrogelator (16-A)2 -V(2+) , comprising an l-alanine-based amphiphile (16-A) and a redox-active viologen based partner (V(2+) ), is reported. The formation the hydrogel depended, not only on the acid-to-amine stoichiometric ratio, but on the choice of the l-amino acid group and also on the hydrocarbon chain length of the amphiphilic component. The redox responsive property and the electrochemical behavior of this two-component system were further examined by step-wise chemical and electrochemical reduction of the viologen nucleus (V(2+) /V(+) and V(+) /V(0) ). The half-wave reduction potentials (E1/2 ) associated with the viologen ring shifted to more negative values with increasing amine component. This indicates that higher extent of salt formation hinders reduction of the viologen moiety. Interestingly, the incorporation of single-walled carbon nanotubes in the electrochemically irreversible hydrogel (16-A)2 -V(2+) transformed it into a quasi-reversible electrochemical system.

Self-assembly of a dendron-attached tetrathiafulvalene: gel formation and modulation in the presence of chloranil and metal ions

The self-assembly of a tetrathiafulvalene (TTF)-based molecular gelator with a dendron substituent into a gel is described. Scanning electron microscope and atomic force microscope studies show that the xerogels exhibit rope-like frameworks or interwoven nanofibers, depending on the polarity of solvent from which the gel is formed. Gels containing chloranil can also be successfully prepared. Interestingly, this two-component gel can be easily transformed into solution after the addition of either Sc³⁺ or Pb²⁺. Both absorption and electron spin resonance (ESR) spectroscopic investigations reveal that the TTF unit is oxidized into TTF+ by chloranil in the presence of either Sc³⁺ or Pb²⁺. Moreover, the gel phase can be restored by reduction of TTF+ into the neutral form using magnesium.