Synthesis and chirality control of bulk crystals and nanocrystals: from a right-handed nonpolar chain to a left-handed polar chain.

Both bulk crystals and nanocrystals of two helical complexes, [Cu(µ2-L)(H2O)]n (1) and {[Cu(µ2-L)(H2O)]·2H2O}n (2) (H2L = thiazolidine-2,4-dicarboxylic acid), have been synthesized with the chiralities of right-handedness (1) and left-handedness (2), respectively. 4-Cyanopyridine and poly(vinylpyrrolidone) (PVP) have been applied to control the synthesis of complexes with different helicities in bulk-crystal and nanocrystal forms, respectively. 2 can be irreversibly transformed to 1 under heating. Associated with the conformation changing, the symmetry alters between nonpolar and polar space groups.

Chiral Ni(II) coordination polymers: structure-driven effects of temperature and polyvinylpyrrolidone.

Chiral Ni(II) coordination compounds with structures of [NiL(H(2)O)(3)] (1) and {[NiL(H(2)O)]·0.5H(2)O}(n) (2) (H(2)L = thiazolidine 2,4-dicaboxlic acid) have been successfully synthesized by the reaction of Ni(CH(3)COO)(2)·4H(2)O and H(2)L in aqueous solution at 25 and 80 °C, respectively. From the same procedure with polyvinylpyrrolidone (PVP) as a surfactant, another corresponding micrometer-scale Ni(II) coordination polymer, {[NiL(H(2)O)(2)]·H(2)O}(n) (3), has been obtained at both 25 and 80 °C, which shows a different structure (one-dimensional, 1D) than both 1 (discrete molecule) and 2 (3D). The conversions of structures and conformations are directed by temperature and surfactant (PVP), as confirmed by powder and single-crystal X-ray diffraction. Circular Dichroism (CD) and Second Harmonic Generation (SHG) measurements of the products have been investigated as well, which indicate the potential applications of these products in chiral and nonlinear optical (NLO) areas.

[Ecosystem service interactions and their affecting factors in Jinghe watershed at county level].

Taking the multiple ecosystem services (grain supply, meat supply, fuel-wood supply, water resource conservation and soil retention) as test objects, this paper analyzed the interactions among these services, the interaction modes and the possible affecting factors in 31 counties of Jinghe watershed. At the county level, there existed great differences in the interactions among different pairs of the ecosystem services. The grain supply showed significant positive correlation with meat supply but negative correlation with soil retention, whereas the water resource conservation showed significant positive correlations with fuel-wood supply and soil retention. As for the interaction modes of the ecosystem services, 24 counties were primarily of regulation services, 3 counties were of supply and regulation services in balance, and 4 counties were primarily of grain supply. The total ecosystem service index of the interaction modes in each county varied greatly, with 5.1 times of difference between the maximum (Jingyuan County) and the minimum value (Yanchi County). The total ecosystem service index was significantly positively correlated with precipitation and soil total nitrogen, and negatively correlated with solar hours. The increase of farmland had negative effects, while that of shrub land and grassland had great positive effects on the total ecosystem service index, but the increase of forestland had less effects.

Temperature-directed structural recurrence in low-symmetric Co(II) complexes and nanocrystals.

Low-symmetric complexes {[Co(µ(2)-L)(H(2)O)(2)]·H(2)O}(n) (1) and {[Co(µ(3)-L)(H(2)O)]·0.5H(2)O}(n) (2) and corresponding nanocrystals were obtained, which exhibit structural recurrence behaviour at various temperatures as well as changes of chiral, nonlinear optical and ferroelectric properties.