Before 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.
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.