Deep red emitting triphenylamine based coumarin-rhodamine hybrids with large Stokes shift and viscosity sensing: Synthesis, photophysical properties and DFT studies of their spirocyclic and open forms
Synthesis of triphenylamine based novel coumarin-rhodamine hybrid dyes. In their open form they show absorption and emission peaks in the deep red region. Larger Stokes shift than reported rhodamine dyes RH-B and RH-101 are found. They exhibit viscosity sensitivity in visible as well as deep red region. Solvent polarity and viscosity works together for the observed emission enhancement.