5,5′‐Diazaisoindigo: an Electron‐Deficient Building Block for Donor–Acceptor Conjugated Polymers

A novel electron-deficient building block, 5,5′-diazaisoindigo (5DNIID), was synthesized through a facile method in good yield. As a derivative of isoindigo, 5DNIID shows an ultra-low LUMO level of −3.92 eV after incorporation of two electron-deficient nitrogen atoms into the para-position of the amine groups in the isoindigo π skeleton. Modified polymerization conditions were applied to efficiently afford the donor–acceptor (D–A) conjugated polymer 5DNIID-2T, which exhibited a p-type charge transport property.