Fluorescence characteristics of 5-aminoquinoline in acetonitrile: Water

Photophysical and spectral properties of 5-aminoquinoline (5-AQ) in acetonitrile: water binary mixture have been studied to understand the excited state relaxation processes occurring in the excited state. Fluorescence of 5-AQ has been found to be quite sensitive to the hydrogen bond donating ability of the solvent mixture and is quenched in the presence of water. Hydrogen bonding in the excited state appears to be responsible for the quenching.     

Polymer micro-environmental effects on the fluorescence characteristics of 5-aminoquinoline and 3-aminoquinoline

In this paper we report the spectral and decay behavior of two probes viz. 5-aminoquinoline (5AQ) and 3-aminoquinoline (3AQ) in three different polymeric systems viz. poly methyl methacrylate (PMMA), polyvinyl alcohol (PVA) and cellulose acetate (CA). Absorption spectra are nearly identical for all the polymers but the emission shows larger shift in case of CA as compared to PMMA and PVA. The behavior is explained on the basis of higher hydrogen bond donating ability in case of CA because of the presence of cellulosic hydrogens. Observed multiexponential decays are explained on the basis of free as well as hydrogen-bonded species and also trapping in various excited state geometries of the matrix.     

Effect of positional substitution of amino group on excited state dipole moments of quinoline

The effect of positional substitution of amino group on the ground and excited state dipole moments of quinoline ring has been investigated using solvatochromic shift methods. The excited state dipole moments of 5aminoquinoline (5AQ) and 3aminoquinoline (3AQ) have been estimated from the spectral data in different non-polar, polar aprotic and polar protic solvents using Bakhshiev and Kawski-Chamma-Viallet equations. It has been observed that both grounds as well as excited state dipole moments for 5AQ are higher than those for 3AQ by approximately a factor of two. Higher values of the excited state dipole moments for both 3AQ and 5AQ as compared to corresponding ground state values have been attributed to intramolecular charge transfer processes. The role of specific solute-solvent interaction on excited state dipole moment in addition to the general solvent effects has been discussed.     

Photochemistry of 5-aminoquinoline in protic and aprotic solvents

Photophysical properties of 5-aminoquinoline (5AQ) have been investigated in various non-polar and polar (protic and aprotic) solvents using steady state and time resolved fluorescence. In aprotic solvents, the spectral maxima depend on the polarity. However, in protic solvents both the fluorescence intensity as well decay time show decrease depending on the hydrogen bonding ability of the solvent. The results suggest that photochemistry 5AQ is quite sensitive towards the polarity as well as protic character of the solvent.     

Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.     

Two connected inverse spectral transforms

We establish a transformation which connects the potentials of the one-dimensional Dirac and Klein-Gordon operators. This transformation links the solutions of the nonlinear evolution equations solvable by means of the two inverse spectral transforms which use the Dirac and Klein-Gordon direct and inverse spectral problems.