scholarly journals Development of Prediction Models for the Reactivity of Organic Compounds with Ozone in Aqueous Solution by Quantum Chemical Calculations: The Role of Delocalized and Localized Molecular Orbitals

2015 ◽  
Vol 49 (16) ◽  
pp. 9925-9935 ◽  
Author(s):  
Minju Lee ◽  
Saskia G. Zimmermann-Steffens ◽  
J. Samuel Arey ◽  
Kathrin Fenner ◽  
Urs von Gunten
Keyword(s):  
Aqueous Solution ◽  
Quantum Chemical Calculations ◽  
Organic Compounds ◽  
Quantum Chemical ◽  
Prediction Models ◽  
Molecular Orbitals ◽  
Localized Molecular Orbitals

scholarly journals Role of redox-inactive metals in controlling the redox potential of heterometallic manganese–oxido clusters

2021 ◽  
Author(s):  
Keisuke Saito ◽  
Minesato Nakagawa ◽  
Manoj Mandal ◽  
Hiroshi Ishikita
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Quantum Chemical Calculations ◽  
Catalytic Reaction ◽  
Quantum Chemical ◽  
Ionic Radius ◽  
Redox Potentials ◽  
Oxygen Evolving ◽  
Highest Occupied Molecular Orbitals

AbstractPhotosystem II (PSII) contains Ca2+, which is essential to the oxygen-evolving activity of the catalytic Mn4CaO5 complex. Replacement of Ca2+ with other redox-inactive metals results in a loss/decrease of oxygen-evolving activity. To investigate the role of Ca2+ in this catalytic reaction, we investigate artificial Mn3[M]O2 clusters redox-inactive metals  [M] ([M]  = Mg2+, Ca2+, Zn2+, Sr2+, and Y3+), which were synthesized by Tsui et al. (Nat Chem 5:293, 2013). The experimentally measured redox potentials (Em) of these clusters are best described by the energy of their highest occupied molecular orbitals. Quantum chemical calculations showed that the valence of metals predominantly affects Em(MnIII/IV), whereas the ionic radius of metals affects Em(MnIII/IV) only slightly.

Electroreduction of Organic Compounds, 23 [1].Preparation of the Highly Strained 1′,3′-Dichlorodispiro[cyclopropane-1,2′-bicyclo[ 1.1.0lbutane-4′,1″-cyclopropane][2]

1993 ◽  
Vol 48 (9) ◽  
pp. 1288-1290 ◽  
Author(s):  
Thomas Strelow ◽  
Jürgen Voss ◽  
Werner Baum
Keyword(s):  
Electrochemical Reduction ◽  
Quantum Chemical Calculations ◽  
Organic Compounds ◽  
Title Compound ◽  
Quantum Chemical ◽  
Highly Strained

The preparation of the title compound 4 by electrochemical reduction of 4,4,8,8-tetrachloro-dispiro[2.1.2.1]octane 3 is described. The geometry of the compounds is discussed in terms of quantum chemical calculations and spectroscopic results.

Methylamination of some 3,6-dinitro-1,8-naphthyridines with liquid methylamine – potassium permanganate

2000 ◽  
Vol 78 (7) ◽  
pp. 950-956
Author(s):  
Marian Wozniak ◽  
Maria Grzegozek ◽  
Piotr Surylo
Keyword(s):  
Quantum Chemical Calculations ◽  
Potassium Permanganate ◽  
Satisfactory Agreement ◽  
Quantum Chemical ◽  
Transition States ◽  
Molecular Orbitals ◽  
Heats Of Formation ◽  
Convenient Synthesis

3,6-Dinitro-1,8-naphthyridine and its 2-substituted derivatives are dehydro-methylaminated with the solution of potassium permanganate in liquid methylamine (LMA–PP) to the corresponding mono- or mono- and bis(methylamino)-3,6-dinitro-1,8-naphthyridines. In the case of 2-chloro- and 2-methoxy-3,6-dinitro-1,8-naphthyridine the replacement of chloro and methoxy substituents by the NHCH3 group occurs as well. Quantum-chemical calculations indicate the reactions to be controlled by the interaction of the frontal molecular orbitals (FMO) of the reagents. Moreover the heats of formation of intermediary methylamino-σ-adducts and transition states are calculated for the reaction studied. The calculations show satisfactory agreement between calculated and observed results. A convenient synthesis of some 2-substituted-3,6-dinitro-1,8-naphthyridines is reported.Key words: methylaminations, calculations PM3, nitro-1,8-naphthyridines, oxidation.

Intermolecular Interactions of Pyridine in Liquid Phase and Aqueous Solution Studied by Soft X-ray Absorption Spectroscopy

2018 ◽  
Vol 232 (5-6) ◽  
pp. 705-722 ◽  
Author(s):  
Masanari Nagasaka ◽  
Hayato Yuzawa ◽  
Nobuhiro Kosugi
Keyword(s):  
Aqueous Solution ◽  
Quantum Chemical Calculations ◽  
Intermolecular Interactions ◽  
Absorption Spectroscopy ◽  
Quantum Chemical ◽  
Bulk Water ◽  
Pure Liquid ◽  
Rich Region ◽  
X Ray ◽  
X Ray Absorption

Abstract Intermolecular interactions of pyridine in liquid and in aqueous solution are studied by using soft X-ray absorption spectroscopy (XAS) at the C, N, and O K-edges. XAS of liquid pyridine shows that the N 1s→π* peak is blue shifted and the C 1s→π* peak of the meta and para sites is red shifted, respectively, as compared with XAS of pyridine gas. These shifts in liquid are smaller than those in clusters, indicating that the intermolecular interaction of liquid pyridine is weaker than that of pyridine cluster, as supported by the combination of quantum chemical calculations of the core excitation and molecular dynamics simulations of the liquid structure. On the other hand, XAS spectra of aqueous pyridine solutions (C5H5N)x(H2O)1−x measured at different molar fractions show that in the pyridine rich region, x>0.7, the C and N 1s→π* peak energies are not so different from pure liquid pyridine (x=1.0). In this region, antiparallel displaced structures of pyridine molecules are dominant as in pure pyridine liquid. In the O K-edge XAS, the pre-edge peaks sensitive to the hydrogen bond (HB) network of water molecules show the red shift of −0.15 eV from that of bulk water, indicating that small water clusters with no large-scale HB network are formed in the gap space of structured pyridine molecules. In the water rich region, 0.7>x, the N 1s→π* peaks and the O 1s pre-edge peaks are blue shifted, and the C 1s→π* peaks of the meta and para sites are red-shifted by increasing molar fraction of water. The HB network of bulk water is dominant, but quantum chemical calculations indicate that small pyridine clusters with the HB interaction between the H atom in water and the N atom in pyridine are still existent even in very dilute pyridine solutions.

scholarly journals Quantum Chemical Investigation of Polychlorinated Dibenzodioxins, Dibenzofurans and Biphenyls: Relative Stability and Planarity Analysis

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5697
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Aromatic Compounds ◽  
Relative Stability ◽  
Quantum Chemical ◽  
Prediction Models ◽  
Toxicity Prediction ◽  
Chemical Methods ◽  
Quantum Chemical Investigation ◽  
Polychlorinated Dibenzodioxins ◽  
Quantum Chemical Methods

All the possible polychlorinated aromatic compounds in the classes of dibenzodioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were studied by the quantum chemical methods of HF/6-311++G(d,p), B3LYP/6-311++G(d,p), and MP2/cc-pVTZ. The calculated stabilities and structures of these compounds were compared with the available data on their abundance and toxicity. Prediction models for trends in energy and planarity among these congeners were proposed. The results discussed here can help contribute to the understanding of the role of dioxin-like compounds (DLCs) in the environment.

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