From discrete [Y(DMF)8][Cu4(µ3-I)2(µ-I)3I2] ion pairs to extended [Y(DMF)6(H2O)2][Cu7(µ4-I)3(µ3-I)2(µ-I)4(I)]1∞and [Y(DMF)6(H2O)3][CuI7CuII2(µ3-I)8(µ-I)6]2∞arrays by H-bond templating in a confined solvent-free environment

Order and disorder in (E)-[1-(biphenyl-4-yl)ethylidene]hydrazine: a structural, spectroscopic and theoretical study

An unexpected global disorder (co-existing rotational disorder and glide disorder) has been observed during an X-ray investigation of the crystal structure of (E)-[1-(biphenyl-4-yl)ethylidene]hydrazine, C14H14N2, at room temperature. When the temperature decreases to 273 K, the disorder disappears, but the quality of the data set is low. The diffraction data were collected again at 110 K. Differential scanning calorimetry (DSC) analysis and polarizing-microscopy experiments, as well as a fourth set of single-crystal data collected at 283 K, proved that the order–disorder transformation occurs continuously. The analyses of these crystal structures and full-range relaxed potential energy surface scans showed that this kind of global disorder is not very difficult to achieve inside the crystal. Experimental and theoretical studiesviaUV–Vis and fluorescence spectra impart an understanding on the prediction methods of optical properties, which are essential for the rational design of biphenyl-based materials with pre-defined properties.

Crystal-to-crystal transformations in heterometallic yttrium(III)-copper(I) iodide derivatives in a confined solvent-free environment: influence of solvated yttrium cations on the nuclearity and dimensionality of iodocuprate clusters

The solvated yttrium iodide precursors [Y(L)(8)]I(3) (L = DMSO or DMF), prepared in situ by stirring YI(3)(Pr(i)OH)(4) in DMSO or DMF, react with CuI in the presence of NH(4)I to give ionic hetero-metallic species [Y(DMSO)(8)][Cu(2)(mu-I)I(4)] (1) and [Y(DMF)(8)][Cu(4)(mu(3)-I)(2)(mu-I)(3)I(2)] (2) in excellent yields. Re-crystallization of 1 from DMF afforded the mixed-solvate complex [Y(DMSO)(6)(DMF)(2)][CuI(3)][I] (3). Compounds 2 and 3 undergo unique crystal-to-crystal transformation via progressive substitution of DMF by water molecules in a confined, solvent-free environment. Thus, crystals of 3 transform into [Y(DMSO)(6)(H(2)O)(2)][CuI(3)][I] (4), whereas a discrete ion-pair assembly of 2 is first converted into a 1-D zig-zag structure [Y(DMF)(6)(H(2)O)(2)](3+)[Cu(7)(mu(4)-I)(3)(mu(3)-I)(2)(mu-I)(4)(I)](1infinity)(3-) (5) and finally into a 2-D sheet containing mixed-valent copper atoms, [Y(DMF)(6)(H(2)O)(3)](3+)[Cu(I)(7)Cu(II)(2)(mu(3)-I)(8)(mu-I)(6)](2infinity)(3-) (6). The bi- and tetrafurcate H-bonding between water ligands on yttrium and iodides of the Cu-I cluster plays a pivotal role in the evolution of structures 4-6. Formation of a wide range of iodocuprate structures in 1-6, from discrete mono-, di- or tetranuclear units to one- and two-dimensional extended arrays, reflects the influence of solvated yttrium cations on the nuclearity and dimensionality of Cu-I clusters. TG-DTA-MS studies and DFT calculations for these complexes have also been carried out in order to determine their thermal stability and have insight about aforesaid transformations.