%0 Journal Article %1 C9SC05012D %A Hoche, Joscha %A Schulz, Alexander %A Dietrich, Lysanne Monika %A Humeniuk, Alexander %A Stolte, Matthias %A Schmidt, David %A Brixner, Tobias %A Würthner, Frank %A Mitric, Roland %D 2019 %I The Royal Society of Chemistry %J Chem. Sci. %K myown %N 48 %P 11013-11022 %R 10.1039/C9SC05012D %T The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes %U http://dx.doi.org/10.1039/C9SC05012D %V 10 %X Fluorophores with high quantum yields are desired for a variety of applications. Optimization of promising chromophores requires an understanding of the non-radiative decay channels that compete with the emission of photons. We synthesized a new derivative of the famous laser dye 4-dicyanomethylen-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM), i.e., merocyanine 4-(dicyanomethylene)-2-tert-butyl-6-3-(3-butyl-benzothiazol-2-ylidene)1-propenyl-4H-pyran (DCBT). We measured fluorescence lifetimes and quantum yields in a variety of solvents and found a trend opposite to the energy gap law. This motivated a theoretical investigation into the possible non-radiative decay channels. We propose that a barrier to a conical intersection exists that is very sensitive to the solvent polarity. The conical intersection is characterized by a twisted geometry which allows a subsequent photoisomerization. Transient absorption measurements confirmed the formation of a photoisomer in unpolar solvents, while the measurements of fluorescence quantum yields at low temperature demonstrated the existence of an activation energy barrier.

@article{C9SC05012D, abstract = {Fluorophores with high quantum yields are desired for a variety of applications. Optimization of promising chromophores requires an understanding of the non-radiative decay channels that compete with the emission of photons. We synthesized a new derivative of the famous laser dye 4-dicyanomethylen-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM){,} i.e.{,} merocyanine 4-(dicyanomethylene)-2-tert-butyl-6-[3-(3-butyl-benzothiazol-2-ylidene)1-propenyl]-4H-pyran (DCBT). We measured fluorescence lifetimes and quantum yields in a variety of solvents and found a trend opposite to the energy gap law. This motivated a theoretical investigation into the possible non-radiative decay channels. We propose that a barrier to a conical intersection exists that is very sensitive to the solvent polarity. The conical intersection is characterized by a twisted geometry which allows a subsequent photoisomerization. Transient absorption measurements confirmed the formation of a photoisomer in unpolar solvents{,} while the measurements of fluorescence quantum yields at low temperature demonstrated the existence of an activation energy barrier.}, added-at = {2019-12-12T08:11:38.000+0100}, author = {Hoche, Joscha and Schulz, Alexander and Dietrich, Lysanne Monika and Humeniuk, Alexander and Stolte, Matthias and Schmidt, David and Brixner, Tobias and Würthner, Frank and Mitric, Roland}, biburl = {https://www.bibsonomy.org/bibtex/28915203a41a5c90fcf0c3a0bdeb3f794/wuerthner_group}, doi = {10.1039/C9SC05012D}, interhash = {5f0cfdabf62e3d091baa7b712c15a11d}, intrahash = {8915203a41a5c90fcf0c3a0bdeb3f794}, journal = {Chem. Sci.}, keywords = {myown}, month = dec, number = 48, pages = {11013-11022}, publisher = {The Royal Society of Chemistry}, timestamp = {2019-12-12T08:12:37.000+0100}, title = {The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes}, url = {http://dx.doi.org/10.1039/C9SC05012D}, volume = 10, year = 2019 }