Electric polarization effects on the electronic spectral shift of centrosymmetric compounds

Abstract

The classic dielectric dipolar Onsager model was extended to include quadrupolar interactions between solute molecules and solvents with different polarities. A multiparametric solvatochromic expression, based on the point quadrupole moment inside a spherical cavity embedded in a dielectric continuum, is applied to centrosymmetric sulfonamide porphyrins, zinc tetraphenyl porphyrin, squaraine and 9,10-dicyanoanthracene, in order to account for the quadrupolar polarization effect of solute molecules. The reaction field polarity functions created respectively by dipole and quadrupole moments are compared and found to be linearly correlated.

Thermal behavior and the solvent effects ofρ-Methoxy Tetraphenylporphyrin (TOMPP), Copper Porphyrin (CuTOMPP), and Nitroporphyrin (CuTOMPP-NO2)

“…Similar result on the solvent on lower Q-band intensity for metalloporphyrins are found and reported as solvatochromism. Those complexes show linear correlation between polarity of solvent and dipole moments of complexes [18]. However, those results confirmed the solvent effect on the electronic absorption.…”

Photophysics of Acyl- and Ester-DBD Dyes: Quadrupole-Induced Solvent Relaxation Investigated by Transient Absorption Spectroscopy

“…Togashi et al developed a solvent relaxation model for linear quadrupolar molecules similar to the Lippert–Mataga approach (see eq ). This model describes the relation between Δν SR , solvent polarizability parameters (dielectric constant ε and refractive index n ), , ground- as well as the excited-state quadrupole moment strengths (Θ gr and Θ ex , respectively), and the solvent cavity radius a , in which the fluorophore is residing in. with …”

“…We found that the strong Stokes shift of these compounds is dominated by geometry changes of the molecule to form the excited intramolecular charge transfer state S 1 (ICT), while solvent relaxation plays only a minor role. From spectral shifts in different solvents, we were able to determine the change in the quadrupole moment of 8.8 ± 3.5 and 11.7 ± 4.9 B for the ester-and acyl-DBD dye, respectively, by generalizing Togashi's theory 25 to planar, parallelogramical quadrupoles. Based on the solvent relaxation times, it was deduced that the acyl-DBD dye has more polar solvent molecules bound in its solvent sphere than the ester-DBD dye.…”

Measuring the Micro-Polarity and Hydrogen-Bond Donor/Acceptor Ability of Thermoresponsive N-Isopropylacrylamide/N-tert-Butylacrylamide Copolymer Films Using Solvatochromic Indicators

“…Polarity is a complex phenomenon and therefore it cannot be described quantitatively by any single physical parameter. [17][18][19] The measurement of polarity is difficult and is usually implemented using optical spectroscopy methods where various empirical polarity scales have been established in order to characterize quantitatively all types of solvent-solute interactions. 20 From these scales, the most widely used and well-established are those based on solvatochromic measurements, i.e.…”