Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague, Czech Republic.
J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic.
J Org Chem. 2023 Jun 2;88(11):6573-6587. doi: 10.1021/acs.joc.2c02706. Epub 2023 May 23.
Three symmetrically and three unsymmetrically substituted cibalackrot (7,14-diphenyldiindolo[3,2,1-:3',2',1'-][1,5]naphthyridine-6,13-dione, ) dyes carrying two derivatized phenyl rings have been synthesized as candidates for molecular electronics and especially for singlet fission, a process of interest for solar energy conversion. Solution measurements provided singlet and triplet excitation energies and fluorescence yields and lifetimes; conformational properties were analyzed computationally. The molecular properties are close to ideal for singlet fission. However, crystal structures, obtained by single-crystal X-ray diffraction (XRD), are rather similar to those of the polymorphs of solid , in which the formation of a charge-separated state followed by intersystem crossing, complemented with excimer formation, outcompetes singlet fission. Results of calculations by the approximate SIMPLE method suggest which ones among the solid derivatives are the best candidates for singlet fission, but it appears difficult to change the crystal packing in a desirable direction. We also describe the preparation of three specifically deuteriated versions of , expected to help sort out the mechanism of fast intersystem crossing in its charge-separated state.
三种对称和三种非对称取代的 cibalackrot（7,14-二苯基二吲哚并[3,2,1-:3',2',1'-][1,5]萘啶-6,13-二酮，）染料带有两个衍生化的苯基环，被合成作为分子电子学的候选物，特别是对于单重态裂变，这是一种对太阳能转换感兴趣的过程。溶液测量提供了单重态和三重态激发能量和荧光产率和寿命；构象性质通过计算进行了分析。这些分子性质非常适合单重态裂变。然而，通过单晶 X 射线衍射（XRD）获得的晶体结构与固态的多晶型物非常相似，在固态中，形成电荷分离态，随后发生系间窜跃，并伴随着激基复合物的形成，这与单重态裂变竞争。近似 SIMPLE 方法的计算结果表明，固态衍生物中哪些是单重态裂变的最佳候选物，但似乎难以朝着理想的方向改变晶体堆积。我们还描述了三种特定氘化版本的制备，预计这将有助于理清其电荷分离态中快速系间窜跃的机制。
