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

Abstract

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).

Organic Electron Acceptors Comprising a Dicyanomethylene‐Bridged Acridophosphine Scaffold: The Impact of the Heteroatom

“…Particularly attractive is the dicyanomethylene [=C(CN) 2 ] unit displaying reversible redox chemistry and chemical robustness. Hence, the dicyanomethylene moiety is found, for example, in the paradigmatic electron acceptors 7,7,8,8‐tetracyanoquinodimethane (TCNQ) or 11,11,12,12‐tetracyano‐9,10‐anthraquinodimethane (TCAQ), functional push–pull chromophores with intense low‐energy intramolecular charge‐transfer (ICT) bands and innovative materials for organic solar cells…”

Origin of Intense Intramolecular Charge‐Transfer Interactions in Nonplanar Push–Pull Chromophores

“…Planar push–pull chromophores featuring intense intramolecular charge‐transfer (CT) interactions have been extensively studied in view of their potential applications in molecular electronics and optoelectronics 1. 2 In contrast, only a limited number of nonplanar low‐molecular‐weight donor–acceptor chromophores has been reported and the impact of nonplanarity on their π‐conjugative and optoelectronic properties not been systematically investigated 3. 4 Nonplanar CT chromophores tend to feature some desirable physical properties compared to their planar counterparts: they are usually more soluble, less aggregating, and more readily sublimable, forming amorphous, rather than crystalline films for potential use in optoelectronic devices 2a.…”

Acenequinocumulenes: Lateral and Vertical π‐Extended Analogues of Tetracyanoquinodimethane (TCNQ)

“…[37,39] In reality,h owever,t he p-expansion does not necessarily result in enhanced acceptor properties,a nd derivativess uch as TCAQ, TCTQ,a nd TCPQ [24,32,[36][37][38] show non-planar structures that give rise to the so-called "butterfly"c onformation and can hinder p-communication ande ffectivec harget ransport. [42] For example, TCTQ and BDCNBA undergo photoinduced electron transfer( PET) almosta se fficiently as fullereneC 60 , [43,44] while TCAQ derivatives have demonstratede ffectiveness in ar ange of PET processes. [42] For example, TCTQ and BDCNBA undergo photoinduced electron transfer( PET) almosta se fficiently as fullereneC 60 , [43,44] while TCAQ derivatives have demonstratede ffectiveness in ar ange of PET processes.…”