Fermentative Metal – Containing Bio-Nano complexes, Quantum Chemical Models of Their Active Centers and Applications in Biotechnologies

The general structure and the functional universal mechanism of the active centers of the fermentative metal-containing bio-nanocomplexes are discussed on the basis of the quantum-chemical approach using the conception “protein — machine”. The process, proceeding taking place in the active centers structure is the result of their interaction with the substrates. The active centers quantum-chemical models represent the electron distribution among the complex molecular orbitals (MO). The interaction of the central ions with the ligands is carried out by the donor-acceptor mechanism: the ions provide the connection of the vacant orbitals and connection of the vacant orbitals and the ligands — the unshared electron pair. One of the coordination bonds is functional, using for the interaction with substrates. From the quantum-chemical point of view the functional mechanism of the bio-nanocomplexes is universal. In the final, it is reduced to the functional electron accepting and the leaving in the molecular antibonding orbitals of the complex, inducing the active center transitions from one state to another. The electron-conformational transitions, the active centers changes at its functioning, the role of its protein surrounding may be explained on a basis of the conception “protein — machine”. The specific properties of the investigated bio-nanosystems are involved in the using of the internal valuable information, that is the process is a wave and occurs self-correlatively, and may be described by Kolmogorov-Petrovskii-Piskunov mathematical model. It is fair to say that the discussing bio-nanosystems are the natural intellectual tools, which may be used in the nanobiotechnologies and the spheres of its application are wide. It is necessary to conclude that the metal-containing bio-nanocomplexes are the self-organizing, self-congruent, nonlinear, open systems.

ADSORPTION OF BENZENE AND PYRIDINE VAPORS BY VARIOUS CARBON ADSORBENTS

For the first time with the help of express-method we compare adsorption of benzene and pyridine vapors by carbon adsorbents (CA) that differ in raw materials, methods of production and textural characteristics. With the BET and Aranovich (AR) equations we define the interval of relative pressure, in which the adsorption of studied components is described by suggested models of polymolecular adsorption, and calculated general characteristics of adsorption. A comparative analysis of these equations shows that adsorption isotherms of benzene vapors should be described with the Aranocich model and pyridine vapors with the BET model. It is stated that the adsorption of both benzene and pyridine is characterized by the low energy constant C that means weak adsorption localization on a carbon surface and difficulty with exact determination of monolayer capacity. We stated that with benzene adsorption by CA and pyridine adsorption by lignite sorbent the area taken by adsorbate molecule exceeds molecule’s own size. Such action is typical for realized specific sorbent-sorbate interaction which is expected by molecular structure of adsorbates and surface state of adsorbents and is proved by the amount of calculated adsorption heat. It is stated that pyridine molecules when adsorbed are oriented in parallel to the adsorbent surface and for benzene molecules such reaction exists only for granular carbon adsorbents. Random orientation of benzene molecules when adsorbed by granular CA can be connected with overall attraction-repulsion effect of π-electron system of benzene and polar groups on the adsorbent surface. We define the exponent of the Dubinin-Astakhov equation using the theory of volume filling of micropores (TVFM), calculate the limiting adsorption volume and size of pores occupied by components. We state that both benzene and pyridine adsorption proceeds similarly in available at size micro- and mesopores of adsorbents. Differences in adsorption behavior of benzene and pyridine with a filled monolayer are probably connected with peculiarities of molecule structure of pyridine which has an additional potential center of adsorption that is an unshared electron pair of nitrogen.

The role of molecular geometry in the Wolff rearrangement of α-diazocarbonyl compounds — Conformational control or structural constraints?

Relaxed scans of potential energy surfaces for the loss of nitrogen from four different diazocarbonyl compounds: 3-diazo-2-butanone (1), 2-diazocyclohexanone (2), methyl diazomalonate (3), and diazo Meldrum's acid (4), were conducted at the B3LYP/6-31+G(d,p) level. The geometries of species and transition states involved in the process were optimized at the B3LYP/6-311+G(3df,2p) level, while electronic energies were computed using the MP2(full)/aug-cc-pVTZ method. These calculations suggest that the rigidity of cyclic molecules, rather than the conformational structure of the starting diazocarbonyl compounds, defines the pathway of the dediazotization reaction. In acyclic diazocarbonyl compounds, loss of nitrogen results in the formation of a carbene, which is stabilized by the overlap of the system of carbonyl group and the unshared electron pair of a singlet carbene. On the contrary, in small- to medium-sized cyclic systems, carbonyl carbenes are unable to attain a stabilizing orthogonal conformation. Consequently, cyclic carbonyl carbenes are less stable, and the concerted Wolff rearrangement becomes the predominant process. Transition states for the concerted Wolff rearrangement and for the formation of carbonyl carbenes have a very similar geometry.Key words: diazocarbonyl compounds, Wolff rearrangement, conformation, carbene, ketene.

Spatial Electron Density Distribution of Chlorine Atoms in Molecules of the Series Cl2C = CXX'

The EFG asymmetry parameters at 35Cl nuclei have been measured for polycrystalline compounds of series Cl2C = CHX (X = OR, OCOR) and Cl2C = C(Cl)OCOR at 77 K. For the Cl trans-atoms in molecules Cl2C = CHX, the q values are equal or close to zero. For the Cl cis-atom of these compounds and for all Cl atoms of compounds Cl2C = C(Cl)OCOR, η ~ 6 - 9%. It was shown that the deviation from the axial symmetry of electron distribution of Cl atoms in these compounds is due to the influence not of the geminal, but of a vicinal atom or group directly through the field. The expected p, π -conjugation between the unshared electron pair of halogen and the Ti-electron system of double bond is absent in the molecules studied.