7,7,8,8-Tetracyanoquinodimethane

Description

7,7,8,8-tetracyanoquinodimethane (TCNQ), with a LUMO at 4.5 eV, is known for the charge-transfer salts formed by its radical anion TCNQ in?photovoltaic, light-emitting diodes, and organic field-effect transistor?devices. TCNQ and its derivatives?have been used as dopants, leading to an increase in hole mobility or to the lowering of injection?barriers. One classic example of such is the treatment of tetrathiafulvene (TTF), an electron donor with TCNQ. TFF and TCNQ form an ion pair, the TTF-TCNQ complex. This process of doping leads to the crystallisation of the ion pair into a one-dimensionally stacked polymer. This polymer consists of segregated stacks of cations and anions of the donors and the acceptors, respectively. The complex crystal is an organic semiconductor that exhibits metallic electric conductivity [1, 2].

Chemical properties

orange to green crystalline powder

The Uses of 7,7,8,8-Tetracyanoquinodimethane

7,7,8,8-Tetracyanoquinodimethane is an electron-acceptor molecule used to form charge-transfer superconductors. It is an effective catalyst used for the ?-chlorination of carboxylic acids using chlorosulfonic acid; the presence of TCNQ suppresses competing free-radical chlorination.

What are the applications of Application

7,7,8,8-Tetracyanoquinodimethane is A biochemical involved in the formation of charge-transfer complexes

Definition

ChEBI: A quinodimethane that is p-quinodimethane in which the methylidene hydrogens are replaced by cyano groups.

Synthesis Reference(s)

Journal of the American Chemical Society, 84, p. 3370, 1962 DOI: 10.1021/ja00876a028
The Journal of Organic Chemistry, 48, p. 1366, 1983 DOI: 10.1021/jo00156a048

General Description

7,7,8,8-Tetracyanoquinodimethane (TNCQ) is a strong electron acceptor as it has four cyano groups and π-conjugation bonds that form charge transferring chains and ion radical salts which are mainly used as p-dopants for the fabrication of a variety of semiconductor applications.