%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 myown %N 2 %P 793-802 %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 %V 12 %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 = {2021-01-21T15:29:29.000+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/2f09b2aa8ceedd373d9078f1f7536e0e1/wuerthner_group}, doi = {10.1039/D0SC05475E}, interhash = {d493dbb2f296f773106a8178b34b25f3}, intrahash = {f09b2aa8ceedd373d9078f1f7536e0e1}, journal = {Chem. Sci.}, keywords = {myown}, number = 2, pages = {793-802}, publisher = {The Royal Society of Chemistry}, timestamp = {2021-01-21T15:29:29.000+0100}, title = {Tuning phenoxyl-substituted diketopyrrolopyrroles from quinoidal to biradical ground states through (hetero-)aromatic linkers}, url = {http://dx.doi.org/10.1039/D0SC05475E}, volume = 12, year = 2021 }