Skonieczny Kamil, Papadopoulos Ilias, Thiel Dominik, Gutkowski Krzysztof, Haines Philipp, McCosker Patrick M, Laurent Adèle D, Keller Paul A, Clark Timothy, Jacquemin Denis, Guldi Dirk M, Gryko Daniel T
Institute of Organic Chemistry, PAS. 44/52 Kasprzaka, 01-224, Warsaw, Poland.
Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 3, 91058, Erlangen, Germany.
Angew Chem Int Ed Engl. 2020 Sep 7;59(37):16104-16113. doi: 10.1002/anie.202005244. Epub 2020 Jul 10.
Red-emissive π-expanded diketopyrrolopyrroles (DPPs) with fluorescence reaching λ=750 nm can be easily synthesized by a three-step strategy involving the preparation of diketopyrrolopyrrole followed by N-arylation and subsequent intramolecular palladium-catalyzed direct arylation. Comprehensive spectroscopic assays combined with first-principles calculations corroborated that both N-arylated and fused DPPs reach a locally excited (S ) state after excitation, followed by internal conversion to states with solvent and structural relaxation, before eventually undergoing intersystem crossing. Only the structurally relaxed state is fluorescent, with lifetimes in the range of several nanoseconds and tens of picoseconds in nonpolar and polar solvents, respectively. The lifetimes correlate with the fluorescence quantum yields, which range from 6 % to 88 % in nonpolar solvents and from 0.4 % and 3.2 % in polar solvents. A very inefficient (T ) population is responsible for fluorescence quantum yields as high as 88 % for the fully fused DPP in polar solvents.
通过三步策略可轻松合成发射红光的π-扩展二酮吡咯并吡咯（DPP），其荧光波长可达λ=750 nm，该策略包括二酮吡咯并吡咯的制备、随后的N-芳基化以及分子内钯催化的直接芳基化。综合光谱分析与第一性原理计算证实，N-芳基化和稠合的DPP在激发后均达到局域激发（S）态，随后通过内转换至具有溶剂和结构弛豫的态，最终发生系间窜越。只有结构弛豫态具有荧光，在非极性和极性溶剂中的寿命分别在几纳秒和几十皮秒范围内。寿命与荧光量子产率相关，在非极性溶剂中荧光量子产率范围为6%至88%，在极性溶剂中为0.4%至3.2%。对于极性溶剂中完全稠合的DPP，荧光量子产率高达88%是由非常低效的（T）布居引起的。
