Betkhoshvili Sergi, Poater Jordi, Moreira Ibério de P R, Bofill Josep Maria
Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona Martí i Franquès 1-11, Barcelona 08028, Spain.
ICREA, Pg. Lluís Companys 23, Barcelona 08010, Spain.
J Org Chem. 2024 Oct 4;89(19):14006-14020. doi: 10.1021/acs.joc.4c01375. Epub 2024 Sep 20.
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. This breaks the direct π-conjugation between unpaired electrons that gives rise to two radical centers and restricts the minimal polyradical identity of the compound to diradical. We show that diradicals and tetraradicals can be designed, and their polyradical character can be modulated by controlling the topology of π-conjugation as long as there is sufficient aromatic stabilization. Henceforth, the bridge between diradicals and tetraradicals is established, leading to the tetraradical(oid) molecule, which has been predicted to have narrow low-spin to high-spin energy gaps in our recent Letter.
在本研究中，我们探索了基于2,2'-(5,11-二氢吲哚并[3,2-]咔唑-3,9-二基)二丙二腈（以下简称 ）的一系列双自由基（类双自由基）。 的中心苯环（CB）上的氢原子被一系列具有不同长度π共轭链以及供电子或吸电子性质的取代基取代，以研究它们如何调节母体化合物的双自由基特性。通过在 的CB环两侧相对位置上与两个基团双键相连，分子的双自由基特性增加到88 - 89%。这打破了产生两个自由基中心的未成对电子之间的直接π共轭，并将化合物的最小多自由基特性限制为双自由基。我们表明，只要有足够的芳香稳定作用，就可以设计双自由基和四自由基，并通过控制π共轭的拓扑结构来调节它们的多自由基特性。自此，双自由基和四自由基之间的桥梁得以建立，从而得到四自由基（类四自由基）分子，在我们最近的一篇快报中预测该分子具有狭窄的低自旋到高自旋能隙。
