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Abstract The zwitterionic molecule Benzo-[f]-Quinolinium Acetyl Benzoyl Methylid (BQABM) is studied in this paper from quantum mechanical and solvatochromic point of view. The nature and contribution of each type of intermolecular interaction to the spectral shifts in different solvents were estimated based on solvatochromic analyze of BQABM visible absorption band. The correlation coefficients for the dependence of the wavenumber in the maximum of BQABM visible band vs. the solvent parameters were computed by Linear Energy Relationships Simulation (LERS). The optimized geometry of BQABM and some physical and chemical parameters for isolated molecule in its ground electronic state were obtained with Spartan'14 programs. The results obtained in quantum mechanical analysis and also LERS correlation coefficients were used to determine the excited state dipole moment of BQABM by a Variational method in McRae and Kawschi hypothesis that the molecular polarizability does not change in the visible absorption process. An increase in the BQABM electric dipole moment by excitation resulted in our study. Graphical Abstract Unlabelled Image Highlights • BQABM is a zwitterionic compound with a visible charge transfer band. • Estimation of interaction strength in each solvent • Excited state dipole moment of BQABM • Angle between the dipole moments in electronic states of visible absorption process [ABSTRACT FROM AUTHOR]

The visible electronic absorption band with intramolecular charge transfer of two pyridazinium ylids having common carbanion and different heterocycles is recorded in solutions and its position is correlated to parameters of some empirical scales of solvents. The nature of the intermolecular interactions in pyridazinium ylid solutions is discussed and the supply of each type of interaction is established based on solvatochromic study. [ABSTRACT FROM AUTHOR]

Highlights: [•] Optical rotatory dispersion is estimated using channeled spectra. [•] Optical rotatory dispersion decreases with light wavelength increasing. [•] The proposed method is validated by data from literature. [ABSTRACT FROM AUTHOR]

Abstract: The spectral shifts in the visible electronic absorption spectra of three amino-nitro-benzene derivatives in different solvents were correlated with the macroscopic parameters (refractive index and electric permittivity) of the solvents. The wavenumbers in the maximum of the visible charge transfer absorption band of o-nitro-aniline, 4-amino-3-nitrophenol and 3-amino-4-nitrophenol depend linearly on the Baur–Nicol function of electric permittivity. This dependence allows to estimate the electric polarizability in the electronic excited states if the electric polarizability in the ground state of the spectrally active molecule is determined by other procedures, such as by quanto-mechanical calculations. [Copyright &y& Elsevier]

The zwitterionic compounds, like ylids, can interact both by universal and specific forces with the protic solvents. Ylids have a visible electronic absorption band with intramolecular charge transfer (ICT), very sensitive to the solvent nature and considered as an indicator of their stability. Two zwitterionic compounds: pyridinium dicarbethoxy methylid and iso-quinolinium dicarbethoxy methylid were studied from solvatochromic point of view and the contribution of solute-solvent specific interactions to the total spectral shift of the visible ICT band was established. Ternary solutions of the studied ylids were used to estimate the difference of interaction energies in molecular pairs ylid-protic solvent and ylid-aprotic solvent in the limits of the cell model of three component solutions. [ABSTRACT FROM AUTHOR]

Abstract: Statistical analysis is applied to study the solvatochromic effects using the solvent parameters (regressors) influencing the spectral shifts in the electronic spectra. The data pointed to eliminate the non-significant parameters and the aberrant points (for which supplemental interactions were neglected in used theories) from those supposed to multi-linear regression. A BASIC program permits to follow these desiderates step by step. In order to exemplify the steps of regression, the wavenumbers of the maximum π–π* absorption band of three benzene derivatives in various solvents were used. [Copyright &y& Elsevier]

Highlights: [•] A schema of electronic levels of the two studied ylids was proposed. [•] Supplies of universal and specific interactions in protic solvents were estimated. [•] Excited state dipole moment of ylids was estimated by spectral methods. [•] Hydrogen bond energy in molecular pair ylids – octanol was also estimated. [ABSTRACT FROM AUTHOR]

Highlights: [•] The spectral study of some DPH+THF multicomponent solutions in ethanol+water binary solvent has been correlated with the computation results. [•] The frequency shifts in absorption spectra, previously attributed to dispersive forces, depend on the ratio of E/W in binary solvent. [•] The molecular composition of the first solvation shell of DPH in multicomponent solutions essentially depends on the content E/W of the binary solvent. [•] In solutions with high water content, THF forms micelles around the DPH molecules, electronic spectra becoming solvent-independent. [Copyright &y& Elsevier]

Abstract: The electronic absorption spectra of 1,6-diphenyl-1,3,5-hexatriene (DPH) were recorded in a great number of solvents with various physico-chemical properties. The dependence of the wavenumber in the maximum of the DPH vibronic bands on the solvent dispersion function demonstrates the prevalence of the dispersion interactions in the studied solutions. Some electro-optical parameters of DPH molecule were computed by HyperChem and were correlated with the results obtained from the solvatochromic effects on DPH. The polarizability in the electronic excited state of DPH has been estimated from the solvatochromic effect. [Copyright &y& Elsevier]

Pyridinium-acetyl-benzoyl-methylid is a cycloimmonium ylid studied here from structural and spectral point of view. Quantum mechanical analysis offers information about the most stable spatial structure, the electro-optical properties in the ground electronic state as well as the QSAR parameters of PABM. The solvatochromic study of the visible absorption band of PABM was made in order to establish the electro-optical features of the ylid in the excited electronic state and also to approximate the contribution of different types of intermolecular interactions in solutions with different solvents. The ternary solutions of PABM were used to estimate the difference between the interaction energies in molecular pairs of the types: ylid-inactive solvent and ylid-active solvent from interaction point of view. [ABSTRACT FROM AUTHOR]

Rhodamine derivatives (B and 6G) are heterocyclic compounds, related to florone. They are widely used as dyes with numerous biotechnological applications. The quantum-mechanical, electro-optical and spectral properties of the isolated molecules in the ground state were determined using molecular modeling programs. The visible electronic absorption spectra of 6G and B Rhodamine were recorded in solvents with different macroscopic parameters. Dipolar moments and polarizabilities of the studied Rhodamines in the excited state were determined by solvatochromic study. [ABSTRACT FROM AUTHOR]

The nature and strength of the intermolecular interactions in the solutions of three azo-benzene derivatives (AD i , i = 1, 2, 3) were established by solvatochromic effects in solvents with different electric permittivities, refractive indices and Kamlet–Taft constants. A quantum mechanical analysis corroborated with spectral data offered information about the excited state dipole moments and polarizabilities of the studied compounds. The separation of the supply of universal and specific interactions to the total spectral shift was made based on the regression coefficients from the equations describing the solvatochromic effect. Supplementary information about the composition of the first solvation shell and the energy in the solute–solvent molecular pairs were obtained analyzing the ternary solutions of AD i , i = 1, 2, 3 compounds in solvent mixture Methanol (M) + n -Hexane (H). [ABSTRACT FROM AUTHOR]

Abstract: Pure and colored with phthalazinium ylids poly(vinyl-alcohol) (PVA) foils were stretched under gentile heating. The birefringence of the thin foils was determined with a Babinet compensator standardized for yellow radiation of a Sodium lamp. The determined birefringence of the colored PVA foils is higher than that of the pure PVA foils. This fact indicates that the phthalazinium ylids facilitate the increase in the anisotropy of the stretched foils. The visible absorption electronic band of phthalazinium ylids was used to estimate the dichroic ratio and the degree of order of the ylid molecules in the stretched PVA foils. An increase in dichroism and birefringence with the degree of stretching has been evidenced for uncolored and colored PVA foils. [Copyright &y& Elsevier]