Engineering Soluble Diketopyrrolopyrrole Chromophore Stacks from a Series of Pd(II)‐Based Ravels**
Irene Regeni, Rituparno Chowdhury, Kai Terlinden, Shinnosuke Horiuchi, Julian J. Holstein, Sascha Feldmann, Guido H. Clever
Abstract
Abstract A strategy to engineer the stacking of diketopyrrolopyrrole (DPP) dyes based on non‐statistical metallosupramolecular self‐assembly is introduced. For this, the DPP backbone is equipped with nitrogen‐based donors that allow for different discrete assemblies to be formed upon the addition of Pd(II), distinguished by the number of π‐stacked chromophores. A Pd 3 L 6 three‐ring, a heteroleptic Pd 2 L 2 L′ 2 ravel composed of two crossing DPPs (flanked by two carbazoles), and two unprecedented self‐penetrated motifs (a Pd 2 L 3 triple and a Pd 2 L 4 quadruple stack), were obtained and systematically investigated. With increasing counts of stacked chromophores, UV/Vis absorptions red‐shift and emission intensities decrease, except for compound Pd 2 L 2 L′ 2 , which stands out with an exceptional photoluminescence quantum yield of 51 %. This is extraordinary for open‐shell metal containing assemblies and explainable by an intra‐assembly FRET process. The modular design and synthesis of soluble multi‐chromophore building blocks offers the potential for the preparation of nanodevices and materials with applications in sensing, photo‐redox catalysis and optics.