Estimation of Dipole Moments of New Coumarin Dye by Experimental and Theoretical Methods

2021 ◽  
Vol 400 (1) ◽  
pp. 2100015
Author(s):  
Omnath Patil ◽  
Ingalagondi P.K. ◽  
S. M. Hanagodimath
2020 ◽  
Vol 98 (8) ◽  
pp. 761-769
Author(s):  
Omnath Patil ◽  
P.K. Ingalagondi ◽  
Shivaraj Gounhalli ◽  
S.M. Hanagodimath

The absorption and fluorescence emission spectra of a newly synthesized laser grade coumarin dye, 1-((4-methoxyphenoxy) methyl)-3H-benzo[f]chromen-3-one (4-MPMBC), have been recorded in various solvents having different polarities. The spectrum peak was found to shift toward a higher wavelength with an increase in the solvent polarity. The dipole moments of the ground state (μg) and excited state (μe) were estimated using the Lippert, Bakshiev, and Kawski–Chamma–Viallet equations. The μe values were found to be greater than the μg values in all solvents, indicating that the dye is more polar in the excited state than in the ground state. The absorption maximum and emission maximum energies, ground- and excited-state dipole moments, and HOMO–LUMO energy gaps were estimated using Gaussian 16W. These have been compared with the experimental results. The estimated chemical hardness of the dye molecule indicates the soft nature in all of the solvents. The reactive centers such as nucleophilic and electrophilic sites were identified along with contour action using electrostatic potential three-dimensional map density functional theory analysis. The fluorescence quenching has been studied in solvents of varying polarities using aniline as a quencher. The quenching process was found to follow the Stern–Volmer equation and was studied by considering the role of diffusion. In all solvents, the probability of quenching per encounter (p) was found to be less than unity. The activation energy for diffusion and activation energy for quenching were estimated using the values of p.


1981 ◽  
Vol 78 ◽  
pp. 155-159 ◽  
Author(s):  
Magdi M. Naoum ◽  
Hakim G. Shinouda ◽  
Ahmed S. Shawali ◽  
Hanna A. Rizk

2019 ◽  
Author(s):  
Kateryna Goloviznina ◽  
José N. Canongia Lopes ◽  
Margarida Costa Gomes ◽  
Agilio Padua

A general, transferable polarisable force field for molecular simulation of ionic liquids and their mixtures with molecular compounds is developed. This polarisable model is derived from the widely used CL\&P fixed-charge force field that describes most families of ionic liquids, in a form compatible with OPLS-AA, one of the major force fields for organic compounds. Models for ionic liquids with fixed, integer ionic charges lead to pathologically slow dynamics, a problem that is corrected when polarisation effects are included explicitly. In the model proposed here, Drude induced dipoles are used with parameters determined from atomic polarisabilities. The CL\&P force field is modified upon inclusion of the Drude dipoles, to avoid double-counting of polarisation effects. This modification is based on first-principles calculations of the dispersion and induction contributions to the van der Waals interactions, using symmetry-adapted perturbation theory (SAPT) for a set of dimers composed of positive, negative and neutral fragments representative of a wide variety of ionic liquids. The fragment approach provides transferability, allowing the representation of a multitude of cation and anion families, including different functional groups, without need to re-parametrise. Because SAPT calculations are expensive an alternative predictive scheme was devised, requiring only molecular properties with a clear physical meaning, namely dipole moments and atomic polarisabilities. The new polarisable force field, CL\&Pol, describes a broad set set of ionic liquids and their mixtures with molecular compounds, and is validated by comparisons with experimental data on density, ion diffusion coefficients and viscosity. The approaches proposed here can also be applied to the conversion of other fixed-charged force fields into polarisable versions.<br>


Author(s):  
Надія Подоляка

The purpose of the article is to investigate the peculiarities of the national Ukrainian culture in the artistic design of the editions of the Kharkov cooperative publishing house «Rukh». Research methods: Empirical-theoretical methods of analysis, synthesis, deduction are used. From the theoretical methods, a description and interpretation is applied. The use of these methods made it possible to prove that the publications of the Kharkov cooperative publishing house «Rukh» are a highly cultured artistic product, shrouded in the aura of the traditions of Ukrainian culture. It is proved that in the 20-ies. XX century. around the «Rukh» united a circle of like-minded writers, critics, editors, illustrators. Book covers were made by M. Samokish, S. Borovoy, V. Krichevsky. It is established that in the graphic design of the editions the editors used font ensembles, decorative elements and other visual materials created by the most prominent representatives of the artistic circles, in which the Ukrainian tradition is traced. In the design of covers used a variety of frames, ornaments of vegetable origin, stylized with letters. At the same time, minimalism of forms, compositions in a black and white version was quite common. Attention is focused on the works of the famous graphs of the era of the Ukrainian revival, created by the order of the Kharkiv cooperative publishing house «Rukh». The features of the national Ukrainian culture in the artistic design of publications are analyzed. Illustrations, graphic elements, style of execution and technique of the Ukrainian artists cooperating with the publishing house are characterized. The study significantly expands the view on publishing at the stage of the formation of Soviet power. The results can be used to write textbooks and teaching aids on cultural studies, the history of publishing and the history of Ukraine.


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