X-ray induced changes in organic and biological crystalline materials

Abstract

A set of Cu-30%Zn,Cu-49%Zn, Cu-65%Zn and Cu-86%Zn (that are in composition range of the phases , ' , and , respectively) have been synthesized by mechanical alloying of the stoichiometric mixtures of pure copper and zinc powders in a planetary mill of high grinding energy by using a ratio weight of the balls/weight of sample (RBS here after) equal to 3.3.The results obtained have shown that the full alloying of the starting mixtures of copper and zinc powders is attained after 3 hours of grinding. The study of the intermediate phases as a function of the grinding time pointed out that the reaction is started with the formation of phases very rich in zinc, like the phase, and continue reacting with copper until the full alloying is achieved. This behavior suggests that the mechanical alloying takes place trough a mechanism that implies the diffusion of copper into the zinc matrix.On the other hand, the grinding under more severe conditions (RBS equal to 13.3) extends considerably the composition range at which phase becomes stabilized. A mechanochemical Cu-Zn binary phase diagram at room temperature is proposed. Recent progress in the solid state coordination and structural chemistry of aromatic disulfonates, as well as the amine interaction properties of crystalline Cd 2+ sulfonate complexes with amines will be presented. [1] Due to the weak coordination strength, most of the metal monosulfonates obtained from aqueous solution are water-coordinated metal sulfonate salts.[2] However, by employing arenedisulfonates, which can provide multiple coordination sites, stable frameworks sustained by sulfonate-metal interactions can be obtained with various dimensionalities. [1] Moreover, due to the flexible coordination modes, the 1,5-naphthalenedisulfonate ligand shows variant coordination modes in complexes obtained from different reaction conditions, resulting in polymorphism.[3] Finally, layered sulfonateand water-coordinated Cd 2+ complexes can selectively uptake amine vapor via solid-state substitution reaction, which is a reversible process at room conditions. [4,5] [1] Cai J., Coord. Chem. Rev., 2004, 248 When the crystal is irradiated with UV or visible light at low temperatures, the averaged molecule in the crystalline lattice reaches the equilibrium state composed of ground and excited states. The structure of the excited molecule in the equilibrium state can be analyzed by X-rays if the occupancy factor of the produced excited molecules exceeds the limiting value (>5%). This method is called equilibrium analysis of excited molecule. Recently we obtained the excited structure of the diplatinum complex with the equilibrium method[1]. The Pt-Pt and Pt-P distances of the diplatinum complex are shortened at the excited state.The same method was applied to the other complex crystals and was successful to observe the structures of the excited molecules. The first example is the (VO)(acac) 2 complex. The unit-cell was expanded at the equilibrium state and the molecular structure indicated that one V=O and...