Leap from Diradicals to Tetraradicals by Topological Control of π-Conjugation.

In this work, we explore the series of diradical(oid)s based on 2,2'-(5,11-dihydroindolo[3,2-]carbazole-3,9-diyl)dimalononitrile (further referred to as ). Hydrogen atoms in the central benzenoid (CB) ring of are substituted by the series of substituents with various lengths of π-conjugated chain and electron-donating or electron-withdrawing properties to study how they modulate the diradical character of the parent compound. The diradical character of molecules increases up to 88-89% by two groups doubly bonded to both sides of the CB ring of in relative positions.

Pathway to Polyradicals: A Planar and Fully π-Conjugated Organic Tetraradical(oid).

In this work, we provide a general strategy to stabilize the ground state of polyradical(oid)s and make higher spin states thermally accessible. As a proof of concept, we propose to merge two planar fully π-conjugated diradical(oid)s to obtain a planar and cross-conjugated tetraradical(oid). Using multireference quantum chemistry methods, we show that the designed tetraradical(oid) is stabilized by aromaticity and delozalization in the π-system and has six thermally accessible spin states within 1.