Pyrrolo[3,2‐b]pyrroles—From Unprecedented Solvatofluorochromism to Two‐Photon Absorption |
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| Authors: | Dr. Daniel H. Friese Alexander Mikhaylov Maciej Krzeszewski Dr. Yevgen M. Poronik Prof. Aleksander Rebane Prof. Kenneth Ruud Prof. Daniel T. Gryko |
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| Affiliation: | 1. Universitetet i Troms?—Norges Arktiske Universitet, Centre for Theoretical and Computational Chemistry Troms?, 9037 Troms? (Norway);2. Department of Physics, Montana State University, Bozeman, MT 59717 (USA);3. Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01‐224 Warsaw (Poland);4. National Institute of Chemical Physics and Biophysics, Akadeemia Tee 23, 12618 Tallinn (Estonia) |
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| Abstract: | A combined experimental and theoretical study of the two‐photon absorption (2PA) properties of a series of quadrupolar molecules possessing a highly electron‐rich heterocyclic core, pyrrolo[3,2‐b]pyrrole, is presented. In agreement with quantum‐chemical calculations, large 2PA cross‐section values, σ2PA≈102–103 GM (1 GM=1050 cm4 s photon?1), are observed at wavelengths of 650–700 nm, which correspond to the two‐photon allowed but one‐photon forbidden transitions. The calculations also predict that increased planarity of this molecule through removal of two N‐substituents leads to further increase in the σ2PA values. Surprisingly, the most quadrupolar pyrrolo[3,2‐b]pyrrole derivative, containing two 4‐nitrophenyl substituents at positions 2 and 5, demonstrates a very strong solvatofluorochromic effect, with a fluorescence quantum yield as high as 0.96 in cyclohexane, whereas the fluorescence vanishes in DMSO. |
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| Keywords: | absorption fluorescence heterocycles solvatochromism structure– activity relationships |
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