Hydrogen bonding in infinite hydrogen fluoride and hydrogen chloride chains

Hydrogen bonding in infinite HF and HCl bent (zigzag) chains is studied using the ab initio coupled-cluster singles and doubles (CCSD) correlation method. The correlation contribution to the binding energy is decomposed in terms of nonadditive many-body interactions between the monomers in the chains, the so-called energy increments. Van der Waals constants for the two-body dispersion interaction between distant monomers in the infinite chains are extracted from this decomposition. They allow a partitioning of the correlation contribution to the binding energy into short- and long-range terms. This finding affords a significant reduction in the computational effort of ab initio calculations for solids as only the short-range part requires a sophisticated treatment whereas the long-range part can be summed immediately to infinite distances.Comment: 9 pages, 4 figures, 3 tables, RevTeX4, corrected typo

Applying solvent retention capacity method (SRC) to evaluate technological quality of wheat flours

Właściwości ziarna pszenicy decydują o kierunku przerobu, doborze parametrów i przebiegu procesów technologicznych, co z kolei determinuje jakość pieczywa. Uwzględniając skalę produkcji, istotne jest opracowanie metody umożliwiającej ocenę jakość mąki z danego ziarna w sposób szybki, a zarazem dokładny. Jednym ze sposobów przewidywania przydatności technologicznej mąki pszennej może być metoda Solvent Retention Capacity (SRC). W metodzie tej wykorzystano zdolność mąki do zatrzymywania wodnych roztworów: Na₂CO₃, sacharozy, kwasu mlekowego oraz wody, co z kolei wynika z obecności uszkodzonych ziarenek skrobiowych, ilości i jakości pentozanów, glutenu i innych składników. Celem przeprowadzonych badań było porównanie właściwości technologicznych mąk pszennych badanych standardowymi metodami analitycznymi z wynikami uzyskanymi metodą SRC. Materiał badawczy dobrano tak, aby reprezentował możliwie szeroki asortyment mąk pszennych, analizowanych na przestrzeni lat 2005-2007. Wyniki uzyskane metodą SRC zestawiono z parametrami jakościowymi badanych mąk i wypieczonych z nich chlebów, a następnie opracowano statystycznie. Stwierdzono istotną ujemną korelację między wartością wchłaniania wody (test SRC) a objętością bochenków. Wykazano, że na podstawie testu SRC można jedynie w niewielkim zakresie przewidzieć jakość pieczywa z analizowanych mąk oraz ma on umiarkowane powiązanie ze wskaźnikami tradycyjnej oceny wartości wypiekowej mąk pszennych.The properties of wheat grain determine the processing lines, choice of parameters, course of technological process, and this, in turn, determines the quality of bread. From the point of view of the production scale, it is essential to develop a method to enable a quick and accurate quality evaluation of flour produced from a particular grain. A Solvent Retention Capacity (SRC) test can be one of the methods applied to assess technological usability of flour. In this method, the capacity of flour was utilized to retain aqueous solutions: Na₂CO₃, sucrose, lactic acid, and water owing to the presence of damaged starch granules, the presence and quality of pentosans, gluten, and other components. The objective of this research performed was to compare the technological properties of wheat flours obtained using standard analytical methods and the relevant results obtained using SRC. The research material was selected so as to have a possibly wide assortment of wheat flours that were analyzed during a period from 2005 to 2007. The results obtained through SRC and the quality parameters of the flours analyzed and of the breads baked from them were compared and statistically elaborated. A significant negative correlation was found between the value of water absorption (SRC test) and the volumes of bread loaves. It was proved that the quality of breads made from the flours analyzed could be predicted on the basis of SRC test only within a small range and that the SRC test is moderately related with the indicators used to evaluate the baking value of wheat flours in a traditional way

The Nature Of The Chemical Bond In Di- And Polynuclear Metal Cluster Complexes As Depicted By The Analysis Of The Electron Localization Function

The bonding in transition metal complexes is usually rationalized based on molecular orbital schemes. Topological approaches such as the atoms in molecules (AIM) theory or the electron localization function (ELF) analysis provides an alternative interpretation of the bonding relying on a local description. These topological theories give a very convenient framework to achieve the partition of the molecular space in regions with chemical meaning such as atoms, bonds and lone pairs. In this work we review the possibility offered by ELF to investigate the bond in di- tri- and tetranuclear metal complexes containing metal-metal bond. In the case of bimetallic complexes with different nominal bond orders of formula M2(formamidinate)4, the metal-metal interaction is associated to a large electron fluctuation between the two metallic cores and interpreted in terms of simple resonance arguments. Such fluctuation between metals can not be invoked for the trinuclear Fe3(CO)12 or the incomplete cuboidal [Mo3S4(PH3)6 Cl3]4+ complexes. The metal-metal interaction in these clusters is mostly characterized by multicenter bonding as is the case for the tetranuclear heterodimetallic cubane-type complexes resulting from the insertion of Cu or Ni into the previous Mo3 S4 complex. © 2005 Académie des sciences. Published by Elsevier SAS. All rights reserved.89-10 SPEC. ISS.14001412Cotton, F.A., (1993) Multiple Bonds Between Metal Atoms, , Oxford, UK: Oxford University Press. second edCotton, F.A., Nocera, D.G., (2000) Acc. Chem. Res., 33, p. 483Gagliardi, L., Roos, B.O., (2003) Inorg. Chem., 42, pp. 1599-1603Bradley, P.M., Smith, L.T., Eglin, J.L., Turro, C., (2003) Inorg. Chem., 42, p. 7360Bader, R.F.W., (1990) A Quantum Theory Atoms in Molecules, , Oxford, UK: Oxford University PressSilvi, B., Savin, A., (1994) Nature, 371, p. 683Fradera, X., Austen, M.A., Bader, R.F.W., (1998) J. Phys. Chem. A, 103, p. 304Cremer, D., Kraka, E., (1984) Angew. Chem. Int. Ed. Engl., 23, p. 67Lewis, G.N., (1919) J. Am. Chem. Soc., 38, p. 762Lewis, G.N., (1966) Valence and the Structure of Atoms and Molecules, , New York: DoverGillespie, R.J., (1972) Molecular Geometry, , London: Van Nostrang ReinholdAslangul, C., Constanciel, R., Daudel, R., Kottis, P., (1972) Aspects of the Localizability of Electrons and Molecules: Loge Theory and Related Methods, , New York: Academic PressDaudel, R., (1971) Aspects De La Chimie Quantique Contemporaine, , Paris: Éd. CNRSBecke, A.D., Edgecombe, K.E., (1990) J. Phys. Chem., 92, p. 5397Silvi, B., (2004) Phys. Chem. Chem. Phys., 6, p. 256Silvi, B., (2003) J. Phys. Chem. A, 107, p. 3081Savin, A., Silvi, B., Colonna, F., (1996) Can. J. Chem., 74, p. 1088Cotton, F.A., (1965) Inorg. Chem., 4, p. 334Cotton, F.A., Feng, X., (1997) J. Am. Chem. Soc., 119, p. 7514Llusar, R., Beltrán, A., Andrés, J., Fuster, F., Silvi, B., (2001) J. Phys. Chem. A, 105, p. 9460Wang, S.G., Schwarz, W.H.E., (1998) J. Chem. Phys., 109, p. 7252Savin, A., Nesper, R., Wengert, S., Fässler, T., (1997) Angew. Chem. Int. Ed. Engl., 36, p. 1808Bianchi, R., Gervasio, G., Marabello, D., (2000) Inorg. Chem., 39, p. 2360Macchi, P., Proserpio, D.M., Sironi, A., (1998) J. Am. Chem. Soc., 120, p. 13429Bianchi, R., Gervasio, G., Marabello, D., (1998) Chem. Commun., 15, p. 1535Llusar, R., Beltrán, A., Andrés, J., Noury, S., Silvi, S., (1999) J. Comput. Chem., 20, p. 1517Silvi, B., Gatti, C., (2000) J. Phys. Chem. A, 104, p. 947Wei, C.H., Dahl, L.F., (1969) J. Am. Chem. Soc., 91, p. 1351Cotton, F.A., Troup, J.M., (1974) J. Am. Chem. Soc., 96, p. 4155Chevreau, H., Martinsky, C., Sevin, A., Minot, C., Silvi, B., (2003) New J. Chem., 27, p. 1049Hunstock, E., Mealli, C., Calhorda, M.J., Reinhold, J., (1999) Inorg. Chem., 38, p. 5053Pilme, J., Silvi, B., Alikhani, M.E., (2003) J. Phys. Chem. A, 107, p. 4506Dewar, M.J.S., (1951) Bull. Soc. Chim., 18Chatt, J., Duncanson, L.A., (1953) J. Am. Chem. Soc., p. 2939Müller, A., Jostes, R., Cotton, F.A., (1980) Angew. Chem. Int. Ed. Engl., 19, p. 875Cotton, F.A., Llusar, R., (1987) Polyhedron, 6, p. 1741Feliz, M., Llusar, R., Andres, J., Berski, S., Silvi, B., (2002) New J. Chem., 26, p. 844Cotton, F.A., Haas, T.E., (1964) Inorg. Chem., 3, p. 10Cotton, F.A., Haas, T.E., (1964) Inorg. Chem., 3, p. 1217Vergamini, P.J., Vahrenkamp, H., Dahl, L.F., (1971) J. Am. Chem. Soc., 93, p. 6327Bursten, B.E., Cotton, F.A., Hall, M.B., Najjar, R.C., (1982) Inorg. Chem., 21, p. 302Jiang, Y., Tang, A., Hoffmann, R., Huang, J., Lu, J., (1985) Organometallics, 4, p. 27Li, J., Liu, C., Lu, J., (1994) Polyhedron, 13, p. 1841Feliz, M., Garriga, J.M., Llusar, R., Uriel, S., Humphrey, M.G., Lucas, N.T., Samoc, M., Luther-Davies, B., (2001) Inorg. Chem., 40, p. 6132Feliz, M., (2003), PhD thesis, Universitat Jaume I, Castelló, SpainBahn, C.S., Tan, A., Harris, S., (1998) Inorg. Chem., 37, p. 2770Llusar, R., Uriel, S., (2003) Eur. J. Inorg. Chem., 7, p. 1271Akashi, H., Uryu, N., Shibahara, T., (1997) Inorg. Chim. Acta, 261, p. 5