Intermolecular Relaxation-Fluctuation Processes and Luminescence Spectra of Solutions

Experimental and theoretical study of hydroxyquinolines: hydroxyl group position dependent dipole moment and charge-separation in the photoexcited state leading to fluorescence

“…This method shows the variation of Stokes shifts with bulk solvent polarity described by dielectric constant (ε) and refractive index (n). Many approaches have been used for calculating ground and excited states dipole moments using solvatochromic method starting from Lippert-Mataga [19][20][21], Bilot and Kawski [22,23], Bilot-Kawski-Chamma-Viallet (BKCV) [22][23][24][25][26][27], Bakhshiev [28] and Suppan [29,30] equations. These approaches are used extensively in the recent past [31][32][33][34][35][36].…”

Comment on ‘temperature dependent spectroscopic and excited state dynamics of 3-hydroxychromones with electron donor and acceptor substituents’

“…Solvatochromic systems are characterised by the next well documented [15][16][17][18][19][20][21][22][23][24] features of the emission bands:…”

“…It is well known that the main mechanism of intermolecular interactions in neutral polar solutions without specific interactions is the dipole-dipole electric interactions of a solute and solvent molecules. Hence, intermolecular interactions depend on the dipole moments and geometric configuration of all molecules [15][16][17][18][19][20][21][22][23].…”

“…Here we give a more detailed explanation of the blue shift of the florescence spectrum with heating of solution. The temperature-induced blue shift is well known effect observed for different organic compounds [15][16][17][18][19][20][21][22][23][24]. It is common to represent the spectral properties of such solutions by the energy level diagram of the spectral centre or solvate consisting of the dye and the nearest solvent molecules.…”

“…Energy levels should take into account free energy of the solvate including not only the electronic and the oscillation energies of the dye molecule but also the energy of intermolecular interactions. Thus, one must consider the dipole-dipole interactions of a solute with the nearest solvent molecules as the strongest interactions in the commonly used polar solutions, and also the thermal fluctuations of these interactions [7,[15][16][17][18][19][20][21][22][23].…”