Thermally induced spectral diffusion of Rhodamine 3B in viscous polyols

Electrophilic Reactivity of Tetrabromorhodamine 123 is Bromine Induced: Convergent Interpretation through Complementary Molecular Descriptors

“…Upon protonation of the oxygen atom bound at the adduct 9-position, elimination is induced yielding the initial conjugated π-system ,, Recovery of 4BrR123 from MeO4BrR123 is attested by electronic absorption and nuclear magnetic resonance patterns. (See also Supporting Information.…”

“…Nevertheless, electrophilicity scales report a decrease of reactivity toward nucleophiles with increasing degree of substitution at the xanthylium π-system. − However, in contrast to other xanthylium based π-systems, rhodamines were not addressed as regards electrophile–nucleophile reactivity. Conversely, solvolyses of other carbocations, mostly photochemically generated as well as of structurally similar molecules lacking the carboxyphenyl group as pyronin Y and thiopyronin were reported. − Nonetheless, the presence of substituents with different donor–acceptor properties can introduce significant alterations in molecular electrophilicity inducing clear changes in the reactivity in particular toward nucleophiles.…”

Electronic Excited-State Behavior of Rhodamine 3B in AOT Reverse Micelles Sensing Contact Ion Pair to Solvent Separated Ion Pair Interconversion

“…R3B in AOT RM electronic transitions − as a function of w 0 . (A) Absorption spectra maximum wavenumbers, λ abs −1 , in liquids and RM as a function of water content.…”

“…Therefore, the simultaneous presence of highly polarizable sulfur atom and the nearby negatively charged oxygen atoms in the proximity of few water molecules at short distances of AOT − , should contribute to additional stabilization of the positively charged π-system of R3B. Oppositely, at higher interionic distances the progressive enrichment of the water solvation layer around R3B will induce the interactions responsible for the π-cation solvatochromism . In CV + , the increase in the blue shoulder region relatively to the absorption maximum is associated with the close proximity of counterions whereas the position of the main absorption peak of CV + −H 2 O closely approaches the position of the main absorption peak of CV + solvated in water/methanol mixtures .…”

“…Different polarity and viscosity were assessed by eq − ν ̅ a,e = ν ̅ a,e v + a a,e ( n 2 − 1 ) 2 n 2 + 1 + b a,e true( ε − 1 ε + 2 − n 2 − 1 n 2 + 2 true) which expresses the variation of spectral maxima wavenumbers of either absorption (a) or emission (e), left-hand side, that shift from the corresponding values in vacuum (v), the first term on the right-hand side, through the second and third terms referring respectively to the contributions of the electronic and orientation polarization. These variations are dominated by the coefficients a a,e and b a,e , revealing the dependence on the Onsager reaction field factor, function of cavity radius, and refractive index of the medium ( n ) in contrast with the dependence on the orientation polarization, expressed in terms of the Debye contribution, function of the optical and static dielectric constants.…”