Novel push–pull π-conjugated compounds suffering steric hindrance between donor and acceptor subunits

A novel push–pull compound with a 1,3-bis(dicyanomethylene)indan-2-ylidene moiety as an acceptor subunit has been prepared along with its two derivatives. These molecules are severely distorted from its planar structure and in solution undergo dynamic interconversion between bent structures. The structural features and UV–vis spectroscopic results indicate that the zwitter-ionic nature of the molecule is enhanced in the ground state, which is also supported theoretically by density functional calculations.