Isolation, characterization, and docking studies of (Z)-isopropyl 7-((1R, 2R, 3R, 5S)-2-((1E, 3Z)-3-fluoro-4-phenoxybuta-1, 3-dienyl)-3,5- dihydroxycyclopentyl) hept-5-enoate, an Impurity of Tafluprost

Introduction: The origin, isolation, and characterization of (Z)-isopropyl 7-((1R, 2R, 3R, 5S)-2-((1E, 3Z)-3-fluoro4-phenoxybuta-1, 3-dienyl)-3, 5-dihydroxycyclopentyl) hept-5-enoate, an impurity found in the preparation of an antiglaucoma agent-Tafluprost has been described. Materials and Methods: Further, an enantiospecific synthesis of (Z)-isopropyl 7-((1R, 2R, 3R, 5S)-2-((1E, 3Z)-3-fluoro-4- phenoxybuta-1, 3-dienyl)-3, 5-dihydroxycyclopentyl) hept-5-enoate has been revealed using deoxofluorination as a key transformation of the strategy. Results and Discussions: Moreover, the impurity showing anti-glaucoma properties in docking studies with respect to bimatoprost. Conclusion: The extent of our work towards docking studies, the present impurity molecule showing almost the same biological activity with respect to Tafluprost.

CH4 Adsorption Probability on GaN(0001) and (000−1) during Metalorganic Vapor Phase Epitaxy and Its Relationship to Carbon Contamination in the Films

Suppression of carbon contamination in GaN films grown using metalorganic vapor phase epitaxy (MOVPE) is a crucial issue in its application to high power and high frequency electronic devices. To know how to reduce the C concentration in the films, a sequential analysis based on first principles calculations is performed. Thus, surface reconstruction and the adsorption of the CH4 produced by the decomposition of the Ga source, Ga(CH3)3, and its incorporation into the GaN sub-surface layers are investigated. In this sequential analysis, the dataset of the adsorption probability of CH4 on reconstructed surfaces is indispensable, as is the energy of the C impurity in the GaN sub-surface layers. The C adsorption probability is obtained based on steepest-entropy-ascent quantum thermodynamics (SEAQT). SEAQT is a thermodynamic ensemble-based, non-phenomenological framework that can predict the behavior of non-equilibrium processes, even those far from equilibrium. This framework is suitable especially when one studies the adsorption behavior of an impurity molecule because the conventional approach, the chemical potential control method, cannot be applied to a quantitative analysis for such a system. The proposed sequential model successfully explains the influence of the growth orientation, GaN(0001) and (000−1), on the incorporation of C into the film. This model can contribute to the suppression of the C contamination in GaN MOVPE.

Прямое наблюдение квазилокализованной низкочастотной колебательной моды в спектре возбуждения флуоресценции одиночной примесной молекулы в полимерной матрице-=SUP=-*-=/SUP=-

The possibility of direct observation of a quasi-localized elementary excitation of the phonon type in polyisobutylene has been demonstrated by detecting the fluorescence excitation spectrum of a Mg‑tetrazaporphyrin single probe molecule in a wide spectral range at a temperature of 6 K. The parameters of the quasilocalized low-frequency vibrational mode have been measured—the frequency (energy) in the case, when impurity molecule is in excited electronic state (ω_ e = 13.94 ± 0.21 cm^–1) and the halfwidth of the mode spectrum (γ = 3.82 ± 0.66 cm^–1). The measured energy of the low-frequency vibrational mode coincides with the position of a boson peak maximum in the spectrum of vibrational states of the polymer, which indicates that the weak coupling approach can be applied to the considered case of the electron–phonon interaction of an organic dye molecule with the local environment in a polymer matrix.

Optical Characterization of Porous Silicon (PS) Doped Erbium (Er) Using Photoluminescence Spectroscopy

The optical properties of porous silicon (PS) doped Erbium (Er) for different amount of Er was investigated.Porous silicon was prepared using electrochemical etching on p-type Si.The weight of Er varies from 0.01g, 0.02, 0.03g and 0.04g and was doped using thermal diffusion technique. Sample was annealed for one hour at temperature of 300oC for diffusion using chemical vapour deposition (CVD).Photoluminescence spectroscopy analysis was performed to investigate the PL properties on PS doped Er. The physical properties of Er doped PS was investigated by Fourier Transform Infrared (FTIR) spectroscopy. The PL results shows that for 0.02g weight of Er doped on PS has the highest peak intensity and quenching effect observed at amount of Er higher than 0.02g doped on PS. From the FTIR analysis shows the existence of Er-O bonding as the impurity molecule which suggests that Er successfully doped onto PS.