Strongly fluorescent halochromic 2,6-di-tert-butyl-phenol-functionalised phenyl-, thienyl- and furyl-substituted diketopyrrolopyrrole (DPP) dyes were deprotonated and oxidised to give either phenylene-linked DPP1˙˙ biradical (y0 = 0.75) with a singlet open shell ground state and a thermally populated triplet state (ΔEST = 19 meV; 1.8 kJ mol−1; 0.43 kcal mol−1) or thienylene/furylene-linked DPP2q and DPP3q compounds with closed shell quinoidal ground states. Accordingly, we identified the aromaticity of the conjugated (hetero-)aromatic bridge to be key for modulating the electronic character of these biradicaloid compounds and achieved a spin crossover from closed shell quinones DPP2q and DPP3q to open shell biradical DPP1˙˙ as confirmed by optical and magnetic spectroscopic studies (UV/vis/NIR, NMR, EPR) as well as computational investigations (spin-flip TD-DFT calculations in combination with CASSCF(4,4) and harmonic oscillator model of aromaticity (HOMA) analysis). Spectroelectrochemical studies and comproportionation experiments further prove the reversible formation of mixed-valent radical anions for the DPP2q and DPP3q quinoidal compounds with absorption bands edging into the NIR spectral region.
%0 Journal Article
%1 D0SC05475E
%A Rausch, Rodger
%A Röhr, Merle I. S.
%A Schmidt, David
%A Krummenacher, Ivo
%A Braunschweig, Holger
%A Würthner, Frank
%D 2021
%I The Royal Society of Chemistry
%J Chem. Sci.
%K ag_pub1 new
%P -
%R 10.1039/D0SC05475E
%T Tuning phenoxyl-substituted diketopyrrolopyrroles from quinoidal to biradical ground states through (hetero-)aromatic linkers
%U http://dx.doi.org/10.1039/D0SC05475E
%X Strongly fluorescent halochromic 2,6-di-tert-butyl-phenol-functionalised phenyl-, thienyl- and furyl-substituted diketopyrrolopyrrole (DPP) dyes were deprotonated and oxidised to give either phenylene-linked DPP1˙˙ biradical (y0 = 0.75) with a singlet open shell ground state and a thermally populated triplet state (ΔEST = 19 meV; 1.8 kJ mol−1; 0.43 kcal mol−1) or thienylene/furylene-linked DPP2q and DPP3q compounds with closed shell quinoidal ground states. Accordingly, we identified the aromaticity of the conjugated (hetero-)aromatic bridge to be key for modulating the electronic character of these biradicaloid compounds and achieved a spin crossover from closed shell quinones DPP2q and DPP3q to open shell biradical DPP1˙˙ as confirmed by optical and magnetic spectroscopic studies (UV/vis/NIR, NMR, EPR) as well as computational investigations (spin-flip TD-DFT calculations in combination with CASSCF(4,4) and harmonic oscillator model of aromaticity (HOMA) analysis). Spectroelectrochemical studies and comproportionation experiments further prove the reversible formation of mixed-valent radical anions for the DPP2q and DPP3q quinoidal compounds with absorption bands edging into the NIR spectral region.
@article{D0SC05475E,
abstract = {Strongly fluorescent halochromic 2{,}6-di-tert-butyl-phenol-functionalised phenyl-{,} thienyl- and furyl-substituted diketopyrrolopyrrole (DPP) dyes were deprotonated and oxidised to give either phenylene-linked DPP1˙˙ biradical (y0 = 0.75) with a singlet open shell ground state and a thermally populated triplet state (ΔEST = 19 meV; 1.8 kJ mol−1; 0.43 kcal mol−1) or thienylene/furylene-linked DPP2q and DPP3q compounds with closed shell quinoidal ground states. Accordingly{,} we identified the aromaticity of the conjugated (hetero-)aromatic bridge to be key for modulating the electronic character of these biradicaloid compounds and achieved a spin crossover from closed shell quinones DPP2q and DPP3q to open shell biradical DPP1˙˙ as confirmed by optical and magnetic spectroscopic studies (UV/vis/NIR{,} NMR{,} EPR) as well as computational investigations (spin-flip TD-DFT calculations in combination with CASSCF(4{,}4) and harmonic oscillator model of aromaticity (HOMA) analysis). Spectroelectrochemical studies and comproportionation experiments further prove the reversible formation of mixed-valent radical anions for the DPP2q and DPP3q quinoidal compounds with absorption bands edging into the NIR spectral region.},
added-at = {2021-01-11T13:37:20.000+0100},
author = {Rausch, Rodger and Röhr, Merle I. S. and Schmidt, David and Krummenacher, Ivo and Braunschweig, Holger and Würthner, Frank},
biburl = {https://www.bibsonomy.org/bibtex/266431cc2dc2182fcb775e1e36d6f4ba4/sagasucy},
doi = {10.1039/D0SC05475E},
interhash = {d493dbb2f296f773106a8178b34b25f3},
intrahash = {66431cc2dc2182fcb775e1e36d6f4ba4},
journal = {Chem. Sci.},
keywords = {ag_pub1 new},
pages = {-},
publisher = {The Royal Society of Chemistry},
timestamp = {2021-01-11T13:53:12.000+0100},
title = {Tuning phenoxyl-substituted diketopyrrolopyrroles from quinoidal to biradical ground states through (hetero-)aromatic linkers},
url = {http://dx.doi.org/10.1039/D0SC05475E},
year = 2021
}