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How To Make Nitroaromatic Compounds Glow: Next‐Generation Large X‐Shaped, Centrosymmetric Diketopyrrolopyrroles
Author(s) -
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.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202005244
Subject(s) - intersystem crossing , fluorescence , intramolecular force , excited state , photochemistry , picosecond , polar , chemistry , internal conversion , nanosecond , solvent , quantum efficiency , population , relaxation (psychology) , materials science , stereochemistry , electron , atomic physics , organic chemistry , optoelectronics , laser , singlet state , optics , psychology , social psychology , physics , demography , quantum mechanics , astronomy , sociology
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 1 ) 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 1 ) population is responsible for fluorescence quantum yields as high as 88 % for the fully fused DPP in polar solvents.