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Switch‐On Diketopyrrolopyrrole‐Based Chemosensors for Cations Possessing Lewis Acid Character
Author(s) -
Kumar G. Dinesh,
Banasiewicz Marzena,
Jacquemin Denis,
Gryko Daniel T.
Publication year - 2021
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.202001376
Subject(s) - bathochromic shift , chemistry , fluorescence , protonation , intersystem crossing , lewis acids and bases , pyridine , ring (chemistry) , crown ether , photochemistry , absorption (acoustics) , stereochemistry , medicinal chemistry , organic chemistry , ion , excited state , catalysis , physics , quantum mechanics , nuclear physics , singlet state , acoustics
For the first time diketopyrrolopyrroles (DPPs) have been synthesized directly from nitriles possessing (aza)crown ethers leading to macrocycle‐dye hybrids. Depending on the nature of the linkage between DPP and macrocyclic ring, various coordination effects are found. The strong interaction of the cations possessing Lewis acid character such as Li + , Mg 2+ and Zn 2+ with 2‐aminopyridin‐4‐yl‐DPPs, leading to a bathochromic shift of both emission and absorption, as well as to strong enhancement of fluorescence was rationalized in terms of strong binding of these cations to the N=C−NR 2 functionality. The same effect has been observed for protonation. Depending on the size and the structure of the macrocyclic ring the complexation of cations by aza‐crown ethers plays an important but secondary role. The interaction of Na + and K + with 2‐aminopyridin‐4‐yl‐DPPs leads to moderate enhancement of fluorescence due to the aza‐crown ethers binding. The very weak fluorescence of DPP bearing 2‐dialkylamino‐pyridine‐4‐yl substituents is due to the closely lying T 2 state and the resulting intersystem crossing.