Self-assembly of π-conjugated bis(terpyridine) ligands with zinc(II) ions: New metallosupramolecular materials for optoelectronic applications

A series of main-chain metallopolymers (P1-P10) was prepared by the self-assembly of rigid-linear π-conjugated bis(terpyridine) monomers (1-10) with ZnII ions and was fully characterized. The polymerization was additionally confirmed by UV/vis titration experiments. A strong increase in viscosities (around 1.6 times) relative to those of the monomer solutions was found. The thermal stability of P1-P10 compared with that of 1-10 was enhanced as a result of the metallopolymerization. The electro-optical properties of the materials were investigated in detail. Tuning of the electrochemical and photophysical properties was enabled; thus, bright purple to green photoluminescent (PL) emission (PL quantum yields of 0.12-0.81) for P1-P10 was observed in solution with the emission color strongly depending on the nature of the π-conjugated bis(terpyridine) system. Thin homogeneous films of P6 were prepared by solution processing, that is, spin-coating and inkjet-printing, and exhibited intense yellow PL emission in the solid state.