Combined Effect of the Linear and Nonlinear Dipole–Dipole Interactions on the Vibrational Spectra of van der Waals Complexes in Solutions

Two‐Photon Solvatochromism II: Experimental and Theoretical Study of Solvent Effects on the Two‐Photon Absorption Spectrum of Reichardt’s Dye

“…However, the effects of solvent on the UV/Vis spectra, as well as on other phenomena, have been known for more than a century. [1,[3][4][5][6][7][8][9][10][11][12][13][14] In 1878, Kundt proposed a rule that related the shift of the UV/Vis absorption-band maximum towards longer wavelengths to the increasing value of the index of refraction. [1,3,4] Nowadays, the term solvatochromism describes a modification of the position and the intensity of UV/Vis absorption bands induced by the change in the polarity of the environment.…”

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].…”