Fluorescent Fe(II) metallo-supramolecular polymers: metal-ion-directed self-assembly of new bisterpyridines containing triethylene glycol chains

Abstract

We synthesized new ditopic bisterpyridine (BTPY) ligands (L2 and L4) containing triethylene glycol (TEG) chains at the ortho-position of the peripheral pyridine ring and succeeded in obtaining fluorescent Fe(II) metallo-supramolecular polyelectrolytes (FeL2-MEPE and FeL4-MEPE) through complexation of Fe(II) ions with L2 and L4, respectively. The Fe(II) ion is known to quench fluorescence, but FeL2-MEPE shows a retention of quantum yield that is nearly threefold higher than that of the unsubstituted analog (FeL3-MEPE). We investigated the substituent effects of TEG chains on metallo-supramolecular polymers and their fluorescent and electrochemical properties in detail.