Abstract
An asymmetric two-arm polypyridine ligand 4'-{4-[4-(2,2'-dipyridyl)phenyl]}-2,2':6',2'-terpyridine (TPY-Ph-BPY) with double coordination units was synthesized using the one-step Suzuki reaction. The metallic supramolecular film was subsequently obtained by the Fe(2+)-induced self-assembly method at the CHCl(3)-H(2)O interface, which displayed a distinct flat and continuous morphology. The supramolecular film-coated ITO electrode demonstrated a reversible electrochemical redox behavior with pronounced color changes between purple and light green. Its solid-state electrochromic device had an optical contrast (ΔT%) of 26.2% at λ(max) = 573 nm with balanced coloring (t(c) = 2.4 s) and bleaching (t(b) = 2.6 s) times and a high current efficiency of 507.8 cm(2)/C. Moreover, good cycling stability with a long-term reversible color change was observed beyond 900 cycles. These results suggested the promising potential of the TPY-Ph-BPY-Fe(II) supramolecular film for electrochromic applications.