Before revision: In 1973, it was discovered that a combination of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) form a strong charge-transfer complex, referred to as TTF-TCNQ.
After revision: In 1973, it was discovered that a combination of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) forms a strong charge-transfer complex, referred to as TTF-TCNQ.