Fluorescein, differences from rose bengal

Rose Bengal differs in reactivity from fluorescein and Eosin because of the iodines at C-2, C-4, C-5, and C-7 which differentiate the reactivity of the phenoxide from the carboxylate and make substitution at C-2 possible in lieu of substitution at C-6. Essentially three different kinds of Rose Bengal derivatives have been synthesized. The most common include derivatives with gegen ions other than sodium at both C-2 and C-6. Many esters of C-2 have been synthesized and compounds with a number of different gegen ions at C-6 have been reported. The rarest derivatives of Rose Bengal are the C-6 ethers, of which only three have been reported. 

Singlet lifetimes, fluorescence quantum yields, and singlet oxygen quantum yields are compared for Rose Bengal, Erythrosin, Eosin, and fluorescein in a number of different solvents in Table 11. In virtually every case water differs from the other solvents studied. 

Fig. 6.5. Change in viscosity number of (—) cis-1,4-polybutadiene and (—) trans-1,4-polybutadiene in benzene solution during visible light irradiation in the presence of oxygen and different dyes used as sensitizers (V, O) fluorescein (FL), ( , ) rose bengal (RS) (A, , A, ) methylene blue (MBL) (x) viscosity of solution irradiated without dyes [1785]. (Reproduced with permission from [1785] published by John Wiley Sons, Inc., 1976.)...

---