Interaction second virial coefficients of dimer co-co from new ab initio potential energy surface

The new 5-site ab initio intermolecular interaction potentials of dimer CO-CO were constructed from quantum mechanics using method CCSD(T) with Dunning's correlation-consistent basis sets aug-cc-pVmZ (m = 2, 3) [7]; ab initio energies were extrapolated to the complete basis set limit aug-cc-pV23Z. The ab initio intermolecular energies were corrected for the basis set superposition error (BSSE) with the counterpoise scheme [8]. The interaction second virial coefficients of dimer CO-CO resulting from the 5-site ab initio analytical potential functions obtained by integration; first-order corrections for quantum effects were included too. The results agree well with experimental data. Keywords: Second virial coefficients, 5-site ab initio potentials

Ab initio calculation of intermolecular potentials, prediction of second virial coefficients for dimers H2-H2, H2-O2, F2-F2 and H2-F2, and Monte Carlo simulations of the vapor-liquid equilibria for hydrogen and fluorine

Die reinen Elemente Wasserstoff, Fluor und Sauerstoff sowie die Mischungen Wasser-stoff-Sauerstoff und Wasserstoff-Fluor besitzen zahlreiche industrielle Anwendungen. Wasserstoff koennte ein erneuerbarer Energietraeger bei Brennstoffzellen-Technologien werden und koennte die anderen wichtigen Brennstoffe verdraengen. Daher ist die Berechnung der thermodynamischen Daten der oben genannten Systeme ein wichtiges Anliegen fuer die praktische Anwendung. Diese Arbeit enthaelt die Ergebnisse der Berechnungen der vier Ab-initio-Paarpoten-tiale fuer die Dimere H2-H2, H2-O2, F2-F2 und H2-F2 der daraus abgeleiteten zweiten Virialkoeffizienten einschliesslich der Quantenkorrekturen 1. Ordnung sowie der thermodynamischen Phasengleichgewichtsdaten der Reinstoffe Wasserstoff und Fluor, wobei letztere mit der Gibbs-Ensemble-Monte-Carlo-Methode (GEMC) berechnet wurden. Die neuen intermolekularen Wechselwirkungspotentiale der Dimere H2-H2, H2-O2, F2-F2 und H2-F2 wurden mit quantenmechanischen Methoden berechnet, und zwar mit Hilfe der Coupled-cluster-Theorie CCSD(T) und unter Verwendung korrelations-konsistenter Basissaetze aug-cc-pVmZ (m = 2, 3, 4); die Ergebnisse wurden zum Basissatzlimit extrapoliert (hier mit aug-cc-pV23Z bezeichnet) und bezueglich des ``basis set superposition error" (BSSE) korrigiert. Die so erhaltene Potentialhyperflaeche fuer das H2-H2-Dimer stimmt gut mit der von Diep und Johnson [25] vorgeschlagenen Hyperflaecheueberein. Zum Vergleich wurden auch stoerungstheoretische Rechnungen mit der Moller-Plesset-Theorie zweiter und vierter Ordnung angestellt sowie Rechnungen mit den Basissaetzen 6-31G und 6-311G, aber die Ergebnisse waren schlechter. Fuer die Abschaetzung der Genauigkeiten der theoretischen Methoden und der Basissaetze wurden verschiedene molekulare Parameter berechnet. Die quantenmechanischen Ergebnisse wurden fuer die Erstellung von vier neuen ana-lytischen Paarpotential-Funktionen verwendet. Die anpassbaren Parameter dieser Funktionen wurden durch Anpassung an die Ab-initio - Wechselwirkungsenergien durch eine globale Minimierung der Fehlerquadrate bestimmt, und zwar durch eine Kombination des Levenberg-Marquardt-Verfahrens und eines genetischen Algorithmus. Aus diesen Funktionen wurden die zweiten Virialkoeffizienten von Wasserstoff und Fluor sowie die Kreuz-Virialkoeffizienten der Systeme Wasserstoff-Sauerstoff und Wasserstoff-Fluor durch Integration ermittelt; dabei wurden Quantenkorrekturen beruecksichtigt. Die Ergebnisse stimmen mit experimentellen Daten-soweit vorhan-den-oder mit empirischen Korrelationen ueberein. Monte-Carlo-Simulationen unter Verwendung der Gibbs-Ensemble-Technik (GEMC) wurden eingesetzt, um mit Hilfe der analytischen Paarpotentiale den Dampfdruck von Wasserstoff und Fluor, die Dichten der koexistierenden fluessigen und gasfoermigen Phasen, die Verdampfungsenthalpie und -entropie im Temperaturbereich 18-32 K fuer Wasserstoff und 60-140~K fuer Fluor zu berechnen. Diese Temperaturintervalle reichen nahe an die kritischen Gebiete der Substanzen heran. Aus den berechneten orthobaren Dichten konnten die kritische Temperatur, der kritische Druck und das kritische Molvolumen abgeschaetzt werden. Die Ergebnisse stimmen gut mit experimentellen Daten sowie mit Berechnungen mit Hilfe von Zustandsgleichungen ueberein. Ferner wurden zur Charakterisierung der Strukturen von Wasserstoff und Fluor die Site-site-Paarkorrelationsfunktionen g(r) ermittelt

Monte carlo simulation of vapor - liquid equilibria of hydrogen using ab initio intermolecular potentials

The vapor-liquid equilibria of pure fluid hydrogen were predicted by Gibbs ensemble Monte Carlo simulation techniques using our two different ab initio intermolecular pair potentials. The ab initio intermolecular interaction potentials were obtained from coupled-cluster calculations, using the CCSD(T) level of theory and Dunning's correlation consistent basis sets aug-cc-pVmZ (m =2, 3) [9]. The phase diagram, critical properties, thermodynamic properties, vapor pressures and orthobaric densities based on them are found to be in very good agreement with experimental data. Keywords: Vapor-liquid equilibria, Gibbs ensemble Monte Carlo simulation, ab initio potentials

Prediction of vapor-liquid equilibria of binary mixtures using quantum calculations and activity coefficient models

In this work, the conductor-like screening model COSMO-SAC (segment activity coefficient) obatained from the density functional theory calculations DFT-VWN-BP with basis set DNP (double numerical basis set augmented with polarization function). The molecular-single sigma profiles were generated by using COSMO calculations. The vapor-liquid equilibria (VLE) for three binary mixtures water(1) - ethanol(2), methanol(1) - benzene(2) and toluene(1) - chlorobenzene(2) were calculated from these sigma profiles. The VLE data of these mixtures turn out to be in good agreement with experimental data as far as such data resulting from the activity coefficient models Wilson [1] and NRTL (non-random two-liquid) [2]. RMS error, mean relative deviation of pressure (MRDp) and mean deviation of vapor composition (MDy) are less than 0.087, 9.052 and 0.065, respectively. Keywords: Vapor-liquid equilibria, conductor-like screening model COSMO-SAC

Insight QSDAR models for prediction of anticancer activity on Hela cell line of new flavonoid isolating from rhizome Zingiber zerumbet SM in Viet Nam

1385-1395This research predicts the anticancer activity on the Hela cell line of new flavonoid kaempferol-3-O-methyl ether isolating from rhizome Zingiber zerumbet SM by using the spectrum data activity relationship (QSDAR) models. This model has been developed for a set of 3-aminoflavonoids based on the simulated-spectral data 13C NMR and 15O NMR resulting from the semi-empirical quantum chemical calculations TNDO/2 SCF. The atomic sites O1, O11, C2, C3, C6, C7, and C2’ in the QSDAR models significantly contribute to anticancer activity resulting from the Genetic algorithm (GA). The best regression model QSDARMLR with the values R2train of 0.9057 and R2test of 0.7137, and the neural network modelQSDARANN I(7)-HL(9)-O(1) with the values R2train of 0.993 and R2pred of 0.971 have been explored to predict the anticanceractivities on Hela cell line for new flavonoid kaempferol-3-O-methyl ether from rhizome Zingiber zerumbet SM in Viet Nam

Insight QSDAR models for prediction of anticancer activity on Hela cell line of new flavonoid isolating from rhizome Zingiber zerumbet SM in Viet Nam

This research predicts the anticancer activity on the Hela cell line of new flavonoid kaempferol-3-O-methyl ether isolating from rhizome Zingiber zerumbet SM by using the spectrum data activity relationship (QSDAR) models. This model has been developed for a set of 3-aminoflavonoids based on the simulated-spectral data 13C NMR and 15O NMR resulting from the semi-empirical quantum chemical calculations TNDO/2 SCF. The atomic sites O1, O11, C2, C3, C6, C7, and C2’ in the QSDAR models significantly contribute to anticancer activity resulting from the Genetic algorithm (GA). The best regression model QSDARMLR with the values R2train of 0.9057 and R2test of 0.7137, and the neural network model QSDARANN I(7)-HL(9)-O(1) with the values R2train of 0.993 and R2pred of 0.971 have been explored to predict the anticancer activities on Hela cell line for new flavonoid kaempferol-3-O-methyl ether from rhizome Zingiber zerumbet SM in Viet Nam.

NGHIÊN CỨU SỬ DỤNG DỮ LIỆU CÁC AXIT BÉO TRONG PHÂN LOẠI HOÁ HỌC THỰC VẬT (CHEMOTAXONOMY) ĐỐI VỚI CÁC LOÀI RONG ĐỎ

In this paper, the compositions and contents of fatty acids in the total lipid extracts of 69 red seaweed samples belonging to 9 families (Gracilariaceae, Hypneaceae, Ceramiaceae, Bangiaceae, Hylamaniaceae, Bonnemaisoniaceae, Phyllophoraceae, Rhodymeniaceae and Halymeniaceae) are studied. According to the results, 56 fatty acids are identified, in which 12 fatty acids were considered “fatty acid markers” for the botanical classification (Chemotaxonomy) of red seaweed species such as C14:0, C15:0, C16:0, C16:1n-7, C18:0, C18:1n-9, C18:1n-7, C18:2n-6, C20:3n-6, C20:4n-6, C20:5n-3 and C22:0. By using principal component analysis method (PCA), the analysis result on two-dimensional chart showed that families of red seaweed are distributed into separate regions. Classification tree diagram of the red seaweed species based on essential fatty acid composition is also given.Chúng tôi đã tiến hành nghiên cứu thành phần và hàm lượng các axit béo trong dịch chiết lipit tổng của 69 mẫu rong đỏ Rhodophyta thuộc 9 họ Gracilariaceae, Hypneaceae, Ceramiaceae, Bangiaceae, Hylamaniaceae, Phyllophoraceae, Rhodymeniaceae, họ Halymeniaceae. Kết quả đã xác định được 56 axit béo trong đó có 12 axit béo là C14:0, C15:0, C16:0, C16:1n-7, C18:0, C18:1n-9, C18:1n-7, C18:2n-6, C20:3n-6, C20:4n-6, C20:5n-3 và C22:0 được sử dụng là những chất đánh dấu cho việc phân loại hoá học thực vật (Chemotaxonomy) đối với các loài rong đỏ. Sử dụng phương pháp phân tích cấu tử chính (PCA), kết quả thể hiện qua giản đồ hai chiều, các họ rong đỏ phân định thành các vùng riêng rẽ. Chúng tôi cũng đưa ra sơ đồ cây phân loại của các loài rong đỏ theo thành phần axit béo chính yếu

A comparison for donor-acceptor interactions between E(PH3)2 and NHEMe ligands (E = C to Pb) of W(CO)5 complexes using energy decomposition analysis method with natural orbitals for chemical valence theory

Quantum chemical calculations at the BP86/TZ2P+ level of theory are performed for a comparison of density functional theory (DFT) between tetrylones [(CO)5W-{E(PH3)2}] (W5-EP2) and tetrylenes [(CO)5W-{NHEMe}] (W5-NHEMe) when E = C to Pb. The EDA-NOCV results suggest that the W-E bond dissociation energies (BDEs) in tetrylone complexes increase from the lighter to the heavier homologues. The W-E bond dissociation energies (BDEs) trend in W5-EP2 comes from the increase in (CO)5W←E(PH3)2 donation and strong electrostatic attraction, and that the ligands E(PH3)2 (EP2) are strong s-donors and very weak π-donors. The W-E BDEs trend in tetrylene complexes W5-NHEMe is opposite to that of the W5-EP2 complexes which decrease from the lighter to the heavier homologues. The NHEMe ligands are strong s-donors and weak π-acceptors. NOCV pairs were used in a description of the chemical bond between the W(CO)5 fragment and the ligands in the transition-metal complexes and the results indicated that the NOCV pairs lead to very valuable description of the bonding situation of the fragment-ligand bond in complexes. Keywords. Density functional theory; Bond dissociation energies (BDEs); Energy decomposition analysis (EDA); Natural Orbitals for Chemical Valence (NOCV)

FLAVONOIDS ISOLATED FROM THE FLOWERS OF CAMELLIA CHRYSANTHA

Camellia chrysantha (the golden camellia, golden tea) is a species of evergreen shrub or small tree belonging to the family Theaceae. The flowers and the leaves of this plant are used as tea and drank for its health benefits. The aim of this study was to investigate the chemical constituents of the flowers of Camellia chrysantha. Five flavonoids were isolated from the flowers of Camellia chrysantha (Theaceae), including (+)-catechin (1), (-)-epicatechin (2), quercetin (3), quercetin-3-O-methyl ether (4) and kaempferol (5). Their chemical structures were elucidated by spectroscopic data analysis and by comparison with those reported in the literature. Among five compounds, compounds 4 was isolated for the first time from this species

A quantum chemical computation insight into the donor-acceptor bond interaction of silver complexes with tetrylene

We computationally investigate the nature of chemical bonding from linear to bent structures of N-heterocyclic carbene-analogues of silver complexes (called tetrylene) AgCl-NHEMe (Ag-NHE) with E = C – Pb using quantum chemical calculations at the BP86 level with the various basis sets def2-SVP, def2-TZVPP, and TZ2P+. The geometry calculations find that the equilibrium structures of Ag-NHE system show major differences in the bonded orientation of NHPb ligand in Ag-NHPb compared with NHE ligands the slighter homologues Ag-NHE (E = C - Sn). The bond dissociation energy results show that the Ag-carbene bond in Ag-NHC is a strong bond and decreases from the slighter to the heavier homologues. The EDA-NOCV results indicate that the ligand NHE in complexes is strong s-donors and very weak π donor. The NOCV pairs of the bonding show small π-back donation from the Ag to the NHEMe ligands. Keywords. N-heterocyclic tetrylene, bond dissociation energy, quantum chemical calculations, bonding analysis