Two new isostructural lead borates , Pb 8 Mg(BO 3 ) 6 and Pb 8 Ca(BO 3 ) 6 , have been synthesized via high temperature solution method. The single crystal structures of title compounds contain ∞ [Pb 8 B 6 O 18 ] 2- double layers composed of planar BO 3 triangles, Pb(2)O 9 and distorted Pb(1)O 5 polyhedra, these layers condense in c -axis, and the MgO 6 (or CaO 6 ) polyhedra fill into the layers, forming a three-dimensional framework. The stereochemical activity of lone pair (SCALP) electrons were found in the Pb(1)O 5 polyhedra, which combine with the BO 3 units, generating strong optical anisotropy . The calculated birefringences of Pb 8 Mg(BO 3 ) 6 and Pb 8 Ca(BO 3 ) 6 using first-principles method are 0.15@1064 nm and 0.12@1064 nm, respectively, which are comparable to the commercial α -BaB 2 O 4 (α-BBO) crystal and imply that they probably can be used as birefringent materials. The electronic structures, density of states of title compounds were calculated by density functional theory (DFT). Meanwhile, the TG-DSC curves, infrared spectral and UV–Vis–NIR diffuse reflectance spectral were measured.
Kelei Zhuo,Yujing Wei,Jingjing Ma,Yujuan Chen,Guangyue Bai
Several alkylmethylimidazolium tetraphenylborates (C n mim-TPB, n = 2–10) were synthesized and explored as ion exchangers in plasticized PVC membranes with very attractive sensing behaviors. And then a series of ion-selective electrodes (ISEs) were prepared and their potentiometric properties were investigated. The proposed electrodes exhibited Nernstian responses to alkylmethylimidazolium-based ionic liquid cations [C n mim] + . These electrodes were successfully applied in the determination of thermodynamic parameters of ionic liquids in aqueous solutions and in the detection of [C n mim] + in tap water and distilled water with satisfactory results. For the as-prepared ISEs, one special and important relationship was observed between the selectivity coefficients and the length of alkyl side chains of interfering cations [C n mim] + . The proper understanding of this relationship should facilitate the development of new method for the determination of ionic liquids using ISEs.
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