Conjugated Metallo-Supramolecular Polymers Containing a Phosphole Unit

A new building block, <b>TPT</b>, composed of the substituted phosphole ring surrounded by two thiophene rings with 2,2′:6′,2″-terpyridine-4′-yl (<i>tpy</i>) end-groups, is prepared and assembled with metal ions (Co²⁺, Cu²⁺, Fe²⁺, Ni²⁺, and Zn²⁺) into metallo-supramolecular polymers (MSPs), and properties of both <b>TPT</b> and the MSPs are compared with those of their counterparts with terthiophene central blocks. A distinct red-shifting of the UV/vis band about by 60–100 nm proves the decrease in the bandgap energy due to replacing the thiophene-2,5-diyl with a phosphole-2,5-diyl central unit, which is due to the lowered aromaticity of phosphole ring compared to the aromaticity of thiophene ring. Assembling <b>TPT</b> with metal ions gives oligomeric chains comprising up to 10 unimeric units in dilute solutions. MSPs with Fe²⁺ and Ni²⁺ ion couplers exhibit very slow constitutional dynamics, while those with Cu²⁺ and Zn²⁺ ion couplers quite fast constitutional dynamics. A metal–ligand charge transfer is observed only for Fe²⁺-MSPs, while luminescence is observed only for Zn²⁺-MSPs, mainly at an excess of Zn²⁺ ions, which indicates a positive effect of the end-capping of MSP chains with these ions.