Cooperativity Between π-π And H-bonding Interactions-a Supramolecular Complex Formed By C_(60) And Exttf

摘要

A highly stable supramolecular complex from C_(60) and exTTF (K_a≈ 10~6 M~(-1)) has been achieved by means of π-π and H-bonding interactions; experimental evidence reveals the formation of a radical-ion pair (τ = 9.3 ps) upon photoexcitation.rnThe strong electron donating character of 2-[9-(l,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-l,3-dithiole (exTTF) has drawn interdisciplinary interest in the fields of non-linear optics, self-assembled monolayers, and photovoltaics. Its peculiar shape, that is, a highly distorted geometry, in which exTTF adopts a butterfly-shape configuration, has resulted in the formation of electrically conducting charge transfer complexes. It is only recently that the geometrical properties of this ditopic molecule have been employed to form supramolecular complexes with geometrically and electronically complementary convex surfaces such as fullerenes.Still, attempts to form supramolecular complexes (C_(60)-exTTF) have been unsuccessful. Molecular tweezers, on the other hand, where two exTTF units are linked through isophthalic ester moieties emerged as powerful complexing agents that give rise to binding constants (K_a) in the range of 3-8 × 10~3 M~(-1).