Crown-annelated tetrathiafulvalenes: synthesis of new functionalised derivatives and spectroscopic and electrochemical studies of metal complexation

Abstract

Synthetic routes to the first unsymmetrical annelated tetrathiafulvalene–S₂O₄ crowns are reported; the methodology is versatile, affording the parent system 8, functionalised derivatives 6, 7 and 9–12, and amphiphilic derivatives 6 and 13. UV–VIS spectroscopic studies of metal binding (Na⁺, Ag⁺ and Ba²⁺) to the crown–TTF systems 8 and 13, and the bis(crown)–TTF 14 have been performed in solution, and stability constants have been calculated. The data establish that for the crown compounds 8 and 13 1 : 1 complexes are formed, whereas for the bis(crown) compound 14 both 1 : 1 [14(Na⁺)] and 1 : 2 [14(Na⁺)₂] complexes are formed. Solution electrochemical studies reveal that metal complexation to the crown unit leads to a small anodic shift in the first oxidation potential of the TTF system. Langmuir–Blodgett films of amphiphilic compound 13 have been assembled on solid substrates by Y-type deposition.