The first two decades of a versatile electron acceptor building block:: 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ)

This critical review surveys the development of the structural and electrochemical knowledge of the TCAQ moiety since its discovery, nearly two decades ago, until the present. Additionally, recent advances in the chemistry and functionalization of this versatile building block are highlighted, with special emphasis on the strategies devoted to the preparation of donor-acceptor molecular and polymeric materials. The applications of TCAQ-based materials in materials science as electrical conductors, molecular rectifiers, in photoinduced electron transfer processes, optoelectronic devices and as electrochiroptical materials are also reviewed (89 references).