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991.
A novel low-symmetry tetrabenzoporphine with D2h symmetry (1) and its zinc complex (2) were prepared via mixed condensation reaction of 5,6-dimethyl phthalimide and 4,5,6,7-tetraphenyl phthalimide with sodium acetate in the presence of zinc acetate. The zinc complex 2 exhibited a split Q band at 640 and 623 nm and a single Soret band at 435 nm. The absorption spectra of 1 and 2 were calculated and analyzed using Hartree-Fock theory based on INDO/S Hamiltonian. 相似文献
992.
Taking Ni(2‐mpac)2(H2O)2 as molecular building block, two novel coordination polymers with the formula of [Ni(2‐mpac)2(4,4′‐bpy)·(4,4′‐bpy)]n ( 1 ) and [Ni(2‐mpac)2(py)·4H2O]n ( 2 ) (2‐mpac = 5‐methyl‐2‐pyrazinecarboxylic acid; 4,4′‐bpy = 4,4′‐bipyridine; py = pyrazine) have been synthesized and structurally characterized by X‐ray single crystal diffraction method. In addition, elemental analysis, IR and magnetism characterization are presented. 相似文献
993.
V. Eyert U. Schwingenschlgl C. Hackenberger T. Kopp R. Frsard U. Eckern 《Progress in Solid State Chemistry》2008,36(1-2):156-161
We present electronic structure calculations for the one-dimensional magnetic chain compounds Ca3CoRhO6 and Ca3FeRhO6. The calculations are based on density functional theory and the local density approximation. We use the augmented spherical wave (ASW) method. The observed alternation of low- and high-spin states along the Co–Rh and Fe–Rh chains is related to differences in the oxygen coordination of the transition metal sites. Due to strong hybridization the O 2p states are polarized, giving rise to extended localized magnetic moments centered at the high-spin sites. Strong metal–metal overlap along the chains leads to a substantial contribution of the low-spin Rh 4d3z2−r2 orbitals to the exchange coupling of the extended moments. Interestingly, this mechanism holds for both compounds, even though the coupling is ferromagnetic for cobalt and antiferromagnetic for the iron compound. However, our results allow to understand the different types of coupling from the filling dependence of the electronic properties. 相似文献
994.
Fe3O4纳米晶的粒径控制合成、表征及其吸波性能 总被引:3,自引:0,他引:3
采用十二烷基磺酸钠和聚乙二醇作为保护剂, 成功地制备出Fe3O4纳米晶. 通过改变实验条件, 可在10~200 nm范围内有效调控Fe3O4纳米晶的粒径. 采用X射线衍射仪、透射电子显微镜和扫描电子显微镜等对样品的微观结构、粒径和形貌进行了分析. 结果表明, 所得尖晶石型Fe3O4纳米晶粒径均匀, 形貌均为球形. 利用振动样品磁场计测量了不同粒径样品的磁性能. 结果显示, 粒径小时, 随着粒径的增加, Fe3O4的饱和磁化强度Ms逐渐增加, 但当粒径增加到80 nm时, Ms达到最大值; 随着粒径的减小, 矫顽力也随之减小. 利用矢量网络分析仪对不同粒径样品的电磁性能和吸波性能进行了研究, 结果表明, 当Fe3O4纳米晶的粒径小于100 nm时, 吸波性能良好, 其中, 粒径为20 nm的样品吸收峰的峰值在8 GHz附近达到了-32 dB. 相似文献
995.
磁性无机-生物复合粒子敏感膜新型电流型免疫传感器的研究 总被引:7,自引:4,他引:3
合成了磁性Fe3O4纳米粒子,利用3-氨基丙基三乙氧基硅烷(APS)进行硅烷化,形成表面带有氨基的磁性Fe3O4纳米复合粒子,再用戊二醛将羊抗人免疫球蛋白G抗体(anti-IgG)固定在该磁性粒子表面,通过磁力将其修饰于固体石蜡碳糊电极表面制作成免疫传感器。与标记HRP的二抗体anti-IgG结合,以对苯二酚作为电子媒介体,实现对人免疫球蛋白G(IgG)的定量检测。IgG测定线性范围为2.5~400μg/L,检出限为0.75μg/L。该免疫传感器制作简单,成本低,表面更新方便,可用于临床血清检测。 相似文献
996.
Rare-earth orthoferrites, RFeO3, and rare-earth iron garnets (RIGs) R3Fe5O12 (R=rare-earth elements) were prepared by citrate-nitrate gel combustion method and characterized by X-ray diffraction method. Isobaric molar heat capacities of these oxides were determined by using differential scanning calorimetry from 130 to 860 K. Order-disorder transition temperatures were determined from the heat capacity measurements. The Néel temperatures (TN) due to antiferromagentic to paramagnetic transitions in orthoferrites and the Curie temperatures (TC) due to ferrimagnetic to paramagnetic transitions in garnets were determined from the heat capacity data. Both TN and TC systematically decrease with increasing atomic number of R across the series. Lattice, electronic and magnetic contributions to the total heat capacity were calculated. Debye temperatures as a function of absolute temperature were calculated for these compounds. Thermodynamic functions like , , Ho, Go, , , , , and have been generated for the compounds RFeO3(s) and R3Fe5O12(s) based on the experimental data obtained in this study and the available data in the literature. 相似文献
997.
M. Dolores Santana Gabriel García Consuelo Vicente-Hernndez Luís García Jos Prez Tefilo Rojo Luís Lezama 《Journal of organometallic chemistry》2008,693(11):2009-2016
The preparation, spectroscopic characterization and magnetic study of N,N′-bis(substituted-phenyl)oxamidate-bridged nickel(II) dinuclear complexes of formula {[Ni(N3-mc)]2(μ-CONC6H4-X)}(PF6)2 (N3-mc = 2,4,4-trimethyl-1,5,9-triazacyclo-dodec-1-ene (Me3-N3-mc) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (Me4-N3-mc), X = 2-Cl, 4-Cl, 2-OCH3, 4-OCH3) are reported. These paramagnetic nickel(II) complexes have been characterized by both one- and two-dimensional (COSY) 1H NMR techniques. The COSY spectrum of 5 has allowed to achieve the assignment of the phenyl protons of the N,N′-diphenyloxamidate. The crystal structures of [Ni(Me3-N3-mc)(μ-CONC6H4-4-Cl)]2(PF6)2 (6), [Ni(Me3-N3-mc)(μ-CONC6H4-4-OMe)]2(PF6)2 (8) and [Ni(Me4-N3-mc)(μ-CONC6H4-2-Cl)]2(PF6)2 (9) have been determined and their magnetic properties have been studied. The value of magnetic coupling between the two nickel(II) ions across the oxamidate bridge [J = − 37.6 (6), −39.9 (8) and −39.7 cm−1 (9)] is sensitive to the distortion of the coordination sphere of the metal ions and the topology of the molecular bridge. 相似文献
998.
Thermal, photophysical and magnetic properties of some novel fullerenol–silane adducts are described. Excellent improvement of thermal stability and high char yield due to the presence of silicon is the key feature of these adducts. Highest luminescence quenching due to maximum π–π electronic interactions between phenyl ring and fullerene are observed in the aromatic-silane adducts and the quenching ability of the aromatic ring reduces with further delocalization of the π-electrons as in naphthyl silane. The alkyl vinyl silane, on the other hand, records better fluorescence intensity owing to increase population of the electron density (+I effect) and non-effective charge transfer complex formation between isolated vinylic double bond and fullerene. Emission peak positions of these adducts are comparable to fullerenol because of control derivatization of fullerene ring causing less perturbation of the symmetric π-electronic system. These adducts are paramagnetic in nature with peaks around 3515 G and higher g-values (2.005–2.009) compared to fullerenol (1.985). The fullerenol–silane adducts are synthesized using fullerenol as substrate and different chloro and alkoxy silanes as silylating agents adopting simple nucleophilic displacement and transesterification reactions. All the fullerenol–silane adducts are characterized spectroscopically. 相似文献
999.
Richard E. Sykora Peter Khalifah Zerihun Assefa Richard G. Haire 《Journal of solid state chemistry》2008,181(8):1867-1875
Colorless single crystals of Gd(IO3)3 or pale pink single crystals of Er(IO3)3 have been formed from the reaction of Gd metal with H5IO6 or Er metal with H5IO6 under hydrothermal reaction conditions at 180 °C. The structures of both materials adopt the Bi(IO3)3 structure type. Crystallographic data are (MoKα, λ=0.71073 Å): Gd(IO3)3, monoclinic, space group P21/n, a=8.7615(3) Å, b=5.9081(2) Å, c=15.1232(6) Å, β=96.980(1)°, V=777.03(5) Z=4, R(F)=1.68% for 119 parameters with 1930 reflections with I>2σ(I); Er(IO3)3, monoclinic, space group P21/n, a=8.6885(7) Å, b=5.9538(5) Å, c=14.9664(12) Å, β=97.054(1)°, V=768.4(1) Z=4, R(F)=2.26% for 119 parameters with 1894 reflections with I>2σ(I). In addition to structural studies, Gd(IO3)3, Er(IO3)3, and the isostructural Yb(IO3)3 were also characterized by Raman spectroscopy and magnetic property measurements. The results of the Raman studies indicated that the vibrational profiles are adequately sensitive to distinguish between the structures of the iodates reported here and other lanthanide iodate systems. The magnetic measurements indicate that only in Gd(IO3)3 did the 3+ lanthanide ion exhibit its full 7.9 μB Hund's rule moment; Er3+ and Yb3+ exhibited ground state moments and gap energy scales of 8.3 μB/70 K and 3.8 μB/160 K, respectively. Er(IO3)3 exhibited extremely weak ferromagnetic correlations (+0.4 K), while the magnetic ions in Gd(IO3)3 and Yb(IO3)3 were fully non-interacting within the resolution of our measurements (∼0.2 K). 相似文献
1000.
Hassan Hadadzadeh S. Jamil A. Fatemi Seyedeh Raziyeh Hosseinian Hamid Reza Khavasi Rainer Pöttgen 《Polyhedron》2008
The structure, spectroscopy and electrochemical properties of a novel dinuclear copper(II) complex, [{Cu(phen)2}2(μ-CH3COO)][PF6]3 where phen = 1,10-phenanthroline, is reported. The crystal structure contains two independent Cu(II) ions, with different geometry around each copper center, which are bridged by an acetate anion. The acetate-bridged ligand shows a syn–anti coordination mode with a trigonal bipyramidal geometry for the Cu(1) center and a distorted square-based pyramidal geometry for the Cu(2) center. The angular structural index parameter τ for Cu(1) and Cu(2) is 0.9 and 0.33, respectively. The copper(II) atoms display a different geometry with a N4O chromophore group and with Cu–O distances of 1.993(5)–1.996(5) Å and Cu–N distances which vary from 1.980(5) to 2.161(6) Å. The intra Cu…Cu separation is 4.9904(5) Å. The effective magnetic moment (μeff) of the complex was measured by the Evans method. The cyclic voltammogram of [{Cu(phen)2}2(μ-CH3COO)][PF6]3 shows two waves at positive potential which are assigned to the two Cu(II/I) reduction couples. 相似文献