Andreea Celia Benchea

Solvatochromic Characterization of Sudan Derivatives in Binary and Ternary Solution

ABSTRACT Sudan derivatives are widely used as dyes for foods, textiles, plastics, paper, and cosmetics. The wavenumbers in the maximum of the electronic absorption bands of two Sudan derivatives in solvents with varying physicochemical properties were correlated with microscopic and macroscopic parameters of solution components. The molecular parameters of the Sudan derivatives in the excited state were estimated using solvatochromic and quantum-mechanical calculations.

Quantum Mechanical and Absorption Spectral Characterization of Rhodamine B in Ternary Solution

ABSTRACT Geometrically optimized structure and quantum mechanical properties of rhodamine B were calculated. Electronic absorption spectra of rhodamine B were studied in a ternary solution of methanol and water. Kamlet–Taft empirical scales were utilized to characterize intermolecular interactions and their contributions to total spectral shifts.

Spectral and Quantum Mechanical Characterization of 3-(2-Benzothiazolyl)-7-(Diethylamino) Coumarin (Coumarin 6) in Binary Solution

ABSTRACT Absorption and fluorescence spectra of 3-(2-benzothiazolyl)-7-(diethylamino) coumarin in various solvents were recorded to characterize intermolecular interactions. The contributions of each interaction to the total spectral shifts were estimated. The properties of coumarin 6 were calculated using density function theory with the hybrid functional B3LYP level theory combined with 6-311 + G basis set. The excited state dipole moment was calculated from the variation of spectral shifts in absorption and fluorescence with solvent permittivity and refractive index using the Lippert–Mataga, Bakhshiev, and Kawski–Chamma–Viallet equations.

Excited state molecular polarizability estimated by solvatochromic means

There are few methods for determining the electro-optical parameters in excited molecular states. Between them, the solvent influence on the electronic (absorption or fluorescence) spectra of organic molecules offer the possibility to estimate the excited state dipole moment and/or polarizability by multiple linear regression between the spectral shifts and solvent macroscopic parameters. A comparative study of the polarizability values determined by spectral means for some benzene derivatives in excited states is made in this paper.There are few methods for determining the electro-optical parameters in excited molecular states. Between them, the solvent influence on the electronic (absorption or fluorescence) spectra of organic molecules offer the possibility to estimate the excited state dipole moment and/or polarizability by multiple linear regression between the spectral shifts and solvent macroscopic parameters. A comparative study of the polarizability values determined by spectral means for some benzene derivatives in excited states is made in this paper.

Solvent empirical scales and their importance for the study of intermolecular interactions

The solvent empirical scales were developed in order to classify the solvents regarding their influence on the absorption or fluorescence spectra of different spectrally active molecules. The intermolecular interactions in binary solutions of three molecule having an intramolecular charge transfer visible absorption band are studied in this paper: 5-[2-(1,2,2,4-tetramethyl-1,2,3,4-tetrahydroquinolin-6-yl)-vinyl]-thiophene-2-carbaldehyde (QTC), 1-cyano-2-{5-[2-(1,2,2,4-tetramethyl-1,2,3,4-tetrahydroquinolin-6-yl)-vinyl]-thiophen-2-yl}-vinyl)-phosphonic acid diethyl ester (QTCP) and p-phenyl pyridazinium-p-nitro-phenacylid (PPNP). The solvent empirical scales with a single parameter (Z scale of Kosower, ET (30) or ETN scale of Reichardt and Dimroth) can be used to describe the strength of intermolecular interactions. The contributions of each type of interactions to the total spectral shift are evaluated using the solvent multiple parameters empirical scales defined by Kamlet and Taft and by Catalan et al.

Spectral and quantum-mechanical characterizations of 7-amino-4-trifluoromethyl coumarin

Coumarins are crystalline compounds utilized in pharmaceutical, food and cosmetic industries. Our study refers to quantum-mechanical and spectral characterization of 7-amino-4-trifluoromethyl coumarin (7-NH2-4-CF3-coumarin or coumarin 151) in order to estimate its stability, reactivity and biological activity. The contribution of different types of interactions to the spectral shifts in homogeneous solutions and the limits in which the excited state dipole moment of the studied molecule can vary are established by solvatochromic study.Coumarins are crystalline compounds utilized in pharmaceutical, food and cosmetic industries. Our study refers to quantum-mechanical and spectral characterization of 7-amino-4-trifluoromethyl coumarin (7-NH2-4-CF3-coumarin or coumarin 151) in order to estimate its stability, reactivity and biological activity. The contribution of different types of interactions to the spectral shifts in homogeneous solutions and the limits in which the excited state dipole moment of the studied molecule can vary are established by solvatochromic study.

Quantum-Mechanical and Solvatochromic Characterization of Quercetin

ABSTRACT Quercetin was subjected to a quantum-mechanical analysis and energetic and electro-optic parameters were evaluated. A solvatochromic study was used to estimate the dipole moment of quercetin in the excited state and to determine the angle between the dipole moments of this molecule in the electronic states responsible for the visible absorption band. The contribution of each type of intermolecular interactions to the total spectral shift experimentally recorded in quercetin solution was also established in this study.

Solvatochromic and Quantum-Mechanical Characterization of Methyl Red

ABSTRACT Quantum-mechanical characterization for methyl red was performed using density function theory. The dipole moment and polarizability in the ground state of methyl red were theoretically calculated. The contribution of intermolecular interactions to spectral shifts in solution and the limits in which the excited states’ dipole moment vary in the neutral form were established by a solvatochromic study. The solvatochromism of the acid and alkaline forms of methyl red was experimentally measured and compared with calculated spectra.

Two (Sulfone-Amidosulphonyl)-Amides Derived from N-(P-Amidobenzoyl)-L-Glutamine; Optimized Synthesis and Toxicity Study

Abstract Two derivatives of glutamine were synthesized and the most convenient physical conditions for obtaining reactions were established in factorial experiments with temperature and time of reactions considered as relevant variables. A quantum-mechanical characterization for the new compounds was performed by using HyperChem 8.0.6 Programs and their physical and chemical properties were theoretically estimated. The toxicity of two new compounds was experimentally determined.

Electro-optical parameters in excited states of some spectrally active molecules

The spectral shifts measured in different solvents are expressed as functions of the solvent macroscopic parameters. The value of the correlation coefficient multiplying the functions of electric permittivity was determined by statistical means. The correlation coefficient depends on the electric dipole moment of the spectrally active molecules. The electro-optical parameters in the ground state of the solute molecules can be approximated by molecular modeling. The excited state parameters are usually estimated using the results obtained both by HyperChem Programme and solvatochromic study. The importance of this approximate method is that it offers information about of the excited state of solute molecule for which our measuring possibilities are very restrictive. The information about the excited electronic state is affected by the limits in which the theories of liquid solutions are developed. Our results refer to two molecules of vitamins from B class, namely B3 and B6.