We have succeeded in preparation of novel paramagnetic Cu(II) complexes composed of tetrathiafulvalene (TTF)-based ligands as electrical conducting units, [Cu-II(Bz-OMe-Bu-t-sae-TTF)(2)], [Cu-II(EDT-bissae-TTF)] and [Cu-II(Bz-bis(OMe-Bu-t-sae)-TTF)]. Electrochemical measurements of these neutral complexes revealed that they exhibited two pairs of redox waves attributed to the oxidation of TTF moieties. Among the newly synthesized TTF complexes, only [Cu-II(EDT-bissae-TTF)] gave a radical salt by electrochemical crystallization, but its resistive behavior was insulating. Field-effect transistors (FET) were fabricated with spin-coated films of [Cu-II(Bz-OMe-Bu-t-sae-TTF)(2)] and [Cu-II(EDT-bissae-TTF)], and their FET performances were very low compared with the conventional organic thin film transistors (OTFT) based on TTF derivatives. Atomic force microscopy (AFM) images of the spin-coated films indicated the non-uniform film surfaces with many small grains leading to the large grain boundaries, which probably causes the low carrier mobility of the FET devices. (C) 2017 Published by Elsevier Ltd.