Guest–Host Complexes of TCNQ and TCNE with Cu3(1,3,5-benzenetricarboxylate)2

A combined spectroscopic and structural study was undertaken to investigate the nature of the incorporation of the electron acceptor guest 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the closely related guest tetracyanoethylene (TCNE) into the host porous framework [Cu3(BTC)2] (BTC = 1,3,5-benzenetricarboxylate)—a guest–host system recently shown to be highly conductive. We find that the guest concentration in the system can be modulated via the synthesis reaction time and temperature. A suite of spectroscopic, X-ray and neutron powder diffraction, and density functional theory techniques revealed the mechanism of guest binding within the framework host, including the guest redox states. This work provides insights into the way that electrical conductivity arises in porous framework host–guest systems and contributes to understanding how fine-tuning framework properties influences conductivity.