6533b7dcfe1ef96bd12728a0

RESEARCH PRODUCT

<title>Coumarin fluorescent probes by electro-optical and laser spectrofluorimetry methods</title>

subject

description

Modified electro-optical absorption and emission methods were used to measure the dipole moments of six coumarin fluorescent probes (CU1, CU4, CU7, CU30, CU120, CU334) in the equilibrated ground, excited Franck-Condon and equilibrated excited states. The measurements were performed in cyclohexane and dioxane at room temperature. The equilibrated ground and excited states dipole measured by electro-optical methods are compared with those derived from other measurements techniques and from semiempirical calculations. Experiments and calculations performed in this work reveal a set of anomalous and interesting properties of CU7 and CU30 in solutions. The spectral dependence of some electro-optical coefficients and, consequently, dipole moments in excited Franck-Condon state indicates that the absorption band is a superposition of several (at least two) electronic transitions. Most probably there are two close- lying singlet electronic states which contribute to the first absorption band. Our electro-optical and laser spectrofluorimetry measurements do not support the formation of twisted intramolecular charge transfer state after optical excitation in the studied coumarins, at least in cyclohexane and dioxane.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.