A new coordination polymer, [Gd（III）（3-H-5-hydroxynicotinato）（ox）l.s（H20）2]n, has been synthesized by a hydrothermal reaction of gadolinium nitrate with 5-hydroxynicotinic acid and ammonium oxalate, and its st...A new coordination polymer, [Gd（III）（3-H-5-hydroxynicotinato）（ox）l.s（H20）2]n, has been synthesized by a hydrothermal reaction of gadolinium nitrate with 5-hydroxynicotinic acid and ammonium oxalate, and its structure has been determined by X-ray crystallography with the following data： triclinic space group PI, CgHgNOIlGd, Mr = 464.42, a = 7.5545（11）, b = 8.1094（12）, c = 10.6947（16） A, a= 103.493（2）, β = 98.385（2）, y= 92.117（2）°, Z= 2, V= 628.5706） A3, F（000） = 444, Dc = 2.454 g.cm^-3,/2 = 5.341 mm^-1, the final R = 0.0188 and wR = 0.0392 for 2634 observed reflections （I 〉 2σ（I））. In the asymmetric unit of the compound, each Gdm ion is bonded to nine oxygen atoms from 3-H-5-hydroxynicotinato and oxalate groups and terminal-coordinated water molecules, respectively, resembling a highly distorted three-capped trigonal geometry. Adjacent GdO9 coordination polyhedra are bridged by three identical independent oxalate groups in a side-by-side manner forming brickwall-like 2D grids, and then further linked through intermolecular hydrogen bonds generating a 3D supramolecular network. Magnetic analysis of the compound shows that weak antiferromagnetic coupling exists among the adjacent Gdm ions.展开更多
文摘A new coordination polymer, [Gd（III）（3-H-5-hydroxynicotinato）（ox）l.s（H20）2]n, has been synthesized by a hydrothermal reaction of gadolinium nitrate with 5-hydroxynicotinic acid and ammonium oxalate, and its structure has been determined by X-ray crystallography with the following data： triclinic space group PI, CgHgNOIlGd, Mr = 464.42, a = 7.5545（11）, b = 8.1094（12）, c = 10.6947（16） A, a= 103.493（2）, β = 98.385（2）, y= 92.117（2）°, Z= 2, V= 628.5706） A3, F（000） = 444, Dc = 2.454 g.cm^-3,/2 = 5.341 mm^-1, the final R = 0.0188 and wR = 0.0392 for 2634 observed reflections （I 〉 2σ（I））. In the asymmetric unit of the compound, each Gdm ion is bonded to nine oxygen atoms from 3-H-5-hydroxynicotinato and oxalate groups and terminal-coordinated water molecules, respectively, resembling a highly distorted three-capped trigonal geometry. Adjacent GdO9 coordination polyhedra are bridged by three identical independent oxalate groups in a side-by-side manner forming brickwall-like 2D grids, and then further linked through intermolecular hydrogen bonds generating a 3D supramolecular network. Magnetic analysis of the compound shows that weak antiferromagnetic coupling exists among the adjacent Gdm ions.
文摘在非线性范式下,本文构建了基于多贝西小波三层变换和单支重构的遗传算法径向基函数神经网络模型(daubechies wavelet-genetic algorithm-radial basis function neural network model,Db3-GA-RBF),探讨了欧盟碳排放权市场的价格预测问题.研究表明:1)欧盟碳排放权交易市场配额三阶段的现货价格波动均具有局部尺度多样性特征,且第3阶段碳价格序列多重分形特征最强,本质上碳排放权市场是一个多重分形与混沌市场;2)Db3-GA-RBF模型能有效地提高数据的准确性和模型的泛化能力,使模型的预测精度更强;3)与其他预测模型效果相比,基于施瓦茨信息准则(Schwartz’s information criterion,SIC)的Db3-GA-RBF(SIC)模型的预测精度大约提高70%.
