42584 2017 eng 1949 1956 6 27 article CrossMark Springer Science+Business Media 1 -- -- -- A comprehensive systematic study of Absorption and fluorescence properties in solvents of varying viscosity and polarity of three novel and red-emitting coumarin-rhodamine hybrid derivatives with differences in the rigidity of their substituents is presented. This includes ethanol-polyethylene glycol, toluene-polyethylene glycol, and tolueneparaffin mixtures. Moreover, protonation-induced effects on the spectroscopic properties are studied. A viscosity-induced emission enhancement was observed for all coumarin-rhodamine hybrid derivatives. MCR2 bearing a julolidine donor showed the expected low sensitivity to viscosity whereas MCR3 with its freely rotatable diphenylamino Substituent revealed a particularly pronounced sensitivity to this parameter. Moreover, MCR2 shows an enhancement in Emission in the open, i.e., protonated form in conjunction with a largely Stokes shift fluorescence in the deep red spectral region. This enables the application of these dyes as viscosity sensors and as far red emitting pH-sensitive probes. Journal of Fluorescence 10.1007/s10895-017-2165-4 1573-4994 1053-0509 Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. 20.10.2017 Norman Scholz A. Jadhav M. Shreykar Thomas Behnke Nithiya Nirmalananthan-Budau Ute Resch-Genger N. Sekar eng uncontrolled Fluorescence eng uncontrolled Dye eng uncontrolled Quantum yield eng uncontrolled Viscosity eng uncontrolled Polarity eng uncontrolled Environment eng uncontrolled Probe eng uncontrolled Coumarin eng uncontrolled Rhodamine eng uncontrolled Synthesis Analytische Chemie Sanitär- und Kommunaltechnik; Umwelttechnik Verlagsliteratur Datei im Netzwerk der BAM verfügbar ("Closed Access")