Small Diameter (3 μm), Large Pore (1500 Å) Octadecylsilica for Capillary Electrochromatography

An ODS packing material was specially designed for CEC to achieve high efficiency. The size of the particles was approximately 3.2 m based on scanning electron microscopy, and the average pore size of the particles was 1500 Å by mercury intrusion porosimetry measurement. The packing materials were used in sol-gel bonded continuous-bed columns. The performance of columns containing these 3 m, 1500 Å ODS particles was evaluated for CEC and compared to 3 m, 80 Å ODS particles. The electroosmotic velocity (EOF) for the 1500 Å ODS material was slightly greater than that for the 80 Å ODS material. An efficiency of 410,000 plates m^–1 was obtained for unretained thiourea with a 30 cm × 75 m i.d. 1500 Å ODS column, which was more than 2 times higher than the efficiency obtained from the 80 Å ODS column.Dedicated to Professor K. Jinno on the occasion of his 60th, birthday.     

Progress of 1.5～1.6 μm Laser Crystals

Eye-safe 1.5～1.6 μm lasers have important applications in optical fiber communication, medicine, laser-range-finding, lidar, etc. Er^3＋ and Yb^3＋ co-doped crystal pumped by diode laser around 976 nm is an attractive method for obtaining 1.5～1.6 μm laser in compact device with high output beam quality. In this paper, the recent research and progress of several important Er^3＋ and Yb^3＋ co-doped laser crystals at 1.5～1.6 μm in authors’ lab are reported.     

Tm3+:NaLa(MoO4)2晶体的1.9 μm准连续激光输出

以0.94 mm厚的c切片7.5%(原子分数)Tm3+:NaLa(MoO4)2晶体为增益介质,采用795.5 nm波长钛宝石激光泵浦,实现了1.9 μm准连续激光输出.当输出镜透过率为6.6%时,激光起振阈值为60 mW,斜率效率为50%,最大输出功率为0.5 W.输出激光波长随输出镜透过率的增大向短波方向移动.实验结果表明,Tm3+:NaLa(MoO4)2晶体是一种性能优良的1.9μm波段激光晶体.     

A μ(1,1)- or μ(1,3)-carboxylate bridge makes the difference in the magnetic properties of dinuclear Mn(II) compounds

Six new dinuclear Mn(II) compounds with carboxylate bridges have been synthesized and characterized by X-ray diffraction: [{Mn(phen)(2)}(2)(μ-RC(6)H(4)COO)(2)](ClO(4))(2) with R = 2-Cl (1), 2-CH(3) (2), 3-Cl (3), 3-CH(3) (4), 4-Cl (5) and 4-CH(3) (6). Compounds 1 and 2 show two μ(1,3)-carboxylate bridges in a syn-anti mode while compounds 3-6 present a very uncommon coordination mode of the carboxylate ligand: the μ(1,1)-bridge. The magnetic properties of these compounds are very sensitive to the bridging mode of the carboxylate ligands. While compounds 1 and 2 (μ(1,3)-bridge) display antiferromagnetic interactions, with J values of -1.41 and -1.66 cm(-1), respectively, compounds 3-6 (μ(1,1)-bridge) show ferromagnetic interactions, with J values of 1.01, 0.98, 1.04 and 1.06 cm(-1), respectively. It is worth noting that compounds 3-6 are the first of their class to be magnetically characterized. The EPR spectra at 4 K for compounds with antiferromagnetic coupling (1 and 2) are more complex than those for compounds with a ferromagnetic interaction (3-6). Quite good simulations can be obtained with the ZFS parameters of the Mn(II) ion D(Mn) ~ 0.095 cm(-1) and E(Mn) ~ 0.025 cm(-1) for compounds 1 and 2 and D(Mn) ~ 0.060 cm(-1) and E(Mn) ~ 0.004 cm(-1) for compounds 3-6.     

Synthesis and Structure of μ-Peroxo-bis(4-bromophenoxotri-p-tolylantimony)

-Peroxo-bis(4-bromophenoxotri-p-tolylantimony) was synthesized by reacting 4-bromophenol with tri-p-tolylstibine in the presence of hydrogen peroxide. According to X-ray diffraction data, the Sb atoms have trigonal bipyramidal coordination. In the centrosymmetric molecule, the two Sb atoms are joined via bridging peroxo group disordered over two sites. The Sb–O(1,2') bond lengths are equal to 1.999(6) and 2.03(1) Å, the Sb···O(2,1') distances are equal to 2.605(9) and 2.626(5) Å, respectively. The lengths of the terminal Sb–O(3) bonds are 2.093(3) Å.     

Syntheses,Structures and Vitro Anticancer Activities of μ_2-O-and μ_2-Dimethylglyoximato-bridged μ_3-O-Tris[di(m-fluorobenzyl)tin] Bis(dimethylglyoximate)

μ_2-O-and μ_2-dimethylglyoximato-bridged μ_3-O-tris[di(m-fluorobenzyl)tin] bis(dimethylglyoximate)(1) has been synthesized by the reaction of di(m-fluorobenzyl)tin dichloride with dimethylglyoxime. Complex 1 was characterized by means of IR,~1H NMR,elemental analysis and X-ray diffraction. It crystallizes in orthorhombic system,space group Pna21 with a = 2.22172(12),b = 1.05566(6),c = 2.15577(12) nm,V = 5.0561(5) nm~3,Z = 4,C_(50)H_(50)F_6N_4O_6Sn_3,Mr = 1273.01,Dc = 1. 6721 g/cm3,μ_(MoΚα) = 15.44 cm~(-1),F(000) = 2520,R = 0.0281 and wR = 0.0683. The stabilities,orbital energies and composition characteristics of some frontier molecular orbitals of 1 have been investigated with the quantum chemistry calculation. The properties of thermogravimetric and vitro anticancer activities of the compound have been discussed.     

New unsymmetrical μ-phenoxo bridged binuclear copper(II) complexes

A series of binuclear Cu^II complexes [Cu₂XL] ⁿ⁺ having two copper(II) ions bridged by different motifs (X = OH^–, MeCO₂ ^–, or Cl^–) have been prepared using the ligands: H₂L¹ = 4-methyl-2-[N-(2-{dimethylamino}ethyl-N-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H₂L² = 4-nitro-2-[N-(2-{dimethylamino}ethyl-N-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H₂L³ = 4-methyl-2-[N-(2-{diethylamino}ethyl-N-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol and H₂L⁴ = 4-nitro-2-[N-(2-{diethylamino}ethyl-N-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol. The complexes have been characterized by spectroscopic, analytical, magnetic and electrochemical measurements. Cryomagnetic investigations (80–300 K) revealed anti-ferromagnetic exchange between the Cu^II ions (–2J in the range –50 to –182 cm^–1). The strength of anti-ferromagnetic coupling lies in the order: OAc > OH > Cl. Cyclic voltammetry revealed the presence of two redox couples, assigned to Cu^II/Cu^II/Cu^II/Cu^I/Cu^I/Cu^I. The first reduction potential is sensitive to electronic effects from the aromatic ring substituents and steric effect on the donor nitrogens (side arm) of the ligand systems.     

Synthesis,structure and reactions of μ-oxobis(arenesulfonatotriarylbismuth)

Hydrolysis of triarylbismuth bis(arenesulfonates) in acetone gives bismuth derivatives of the general formula [Ar₃Bi(OSO₂Ar)]₂O (Ar = Ph, p-Tol; Ar = Ph, C₆H₄Me-4, C₆H₃Me₂-2,4, C₆H₃Me₂-3,4). The structure of -oxobis[(3,4-dimethylbenzenesulfonato)triphenylbismuth] was established by means of X-ray diffraction. The molecule has a linear centrosymmetric structure with the bridging oxygen atom in the inversion center. The bismuth atom has a distorted trigonal bipyramidal coordination with the bridging oxygen atom and the arenesulfonate group in axial positions. The Bi-C and Bi-O_term distances are 2.200(2), 2.204(3), and 2.442(2) Å, and the Bi-O_br distances are 2.067(1) Å.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1466–1471.Original Russian Text Copyright © 2004 by Sharutin, Egorova, Sharutina, Ivanenko, Pavlushkina, Gerasimenko, Pushilin.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and Magnetism of μ-IsophthalatoOxovanadium(Ⅱ) Binuclear Complexes

INTRoDUCTIONThestudyoflong-rangemagneticinteractiotisofbinuclearcom-plexeswithextendedbridgedstructureareofcurrentinterestinrecentyears.Inviewoftheeffectivebridgingfunctionofisophthalatedianion(abbreviatedasIPHTA),thispa-perdealswiththesguthesis,characterizationandrnagnetismoftwonewp-IPHTAoxo-vanadium(ll)binuclearcomplexes.Synthesisof[(Vo),(IPHTA)(phen),]SO4(1)Asolutionofpiperidiniumisophthalate'(134.4mg,O.4mmol)andphen(l44.2mg,o.8mmol)inmethanol(1omL)wasaddedslow1ytoamethanolsolut…     

Ion beam-induced magnetic patterning at the sub-0.1 μm level

We present a method that allows magnetic patterning of a continuous magnetic film without significant modification of the surface roughness or of the film's optical indices. It involves ion irradiation of Co/Pt multilayers, using either a standard ion implantation technology combined with high resolution masking, or a focussed ion beam. We fabricated arrays of lines or dots whose magnetic properties differ on a sub-100 nm scale. We describe the ion collision physics on which the techniques are based, as well as some of the observed consequences on the micromagnetic properties of the arrays and on the ultimate resolution. Possible applications to high-density information storage are briefly discussed.     

Trinuclear Cu(II) and Zn(II) complexes bridged by μ3-carbonato anion

The trinuclear Cu(II) and Zn(II) complexes [(CuTPA),(μ₃-CO,)] (C10₄)₄(1) and [(ZnTPA),(μ₃-C0₃)](C10₄)₄ (2) (TPA = tri(pyridylmethy1)amine) have been synthesized. X-ray structure analysis of the two complexes proves that CO₃ ^2- anion has an unusual triply bridging ligand, bridging three CuTPA and ZnTPA units respectively, and assembles new trinuclear complexes. The CO₃ ²- comes from atmospheric CO₂. The structure of each trinuclear unit consists of three copper or zinc atoms in a five-coordinate triangular hipyramidal environment. The [(CuTPA)₃(μ₃-C0₃) ](C10₄), compound shows a very weak antifemmagnetic coupling. Project supported by the National Natural Science Foundation of China (Grant No.29771021).     

SOLUBLE POLY-(o, m)-TOLUIDINE

The soluble poly-o-toluidine (POT) and poly-m-toluidine (PMT) have been success-fully prepared under controlled conditions of polymerization and post-treatment, andcharacterized by IR, VPO and elemental analysis. It is found that the soluble and insol-uble polymers obtained with two different methods (Ⅰ and Ⅱ) have the similar conduc-tivity and molecular chain structure. VPO measurement shows that the number averagemolecular weight (Mn) of soluble polymers is about 3000. The mole ratio of benzoidto quinoid is about 3:1 according to ~1H-NMR and elemental analysis. Free-standingfilms of intrinsic POT and PMT have been obtained by casting their CHCl_3, THF orDMF solutions onto a glass surface.     

PREPARATION AND CHARACTERIZATION OF BINUCLEAR μ-PHENOLATOCOPPER(II)CHELATES.

Two new water-soluble binuclear copper(II)chelates derived from the condensationof 2,6-diformyl-4-methylphenol with glycylglycine were characterized with spectral.magnetic and electrochemical techniques.     

Synthesis and magnetism of μ-isophthalato dinuclear lanthanide(Ⅲ) complexes

Seven new μ-isophthalato dinuclear lanthanide(Ⅲ) complexes, namely [Ln2(IPHTA)(Me2-phen)4-(ClO4)2](ClO4)2 (Ln = La, Nd, Sm, Eu, Gd, Ho, Er), where Me2-phen denotes 2,9-dimethyl-1, 10-phenanthroline (Me2-phen) , IPHTA represents isophthalate dianion, have been synthesized and characterized by elemental analyses, molar conductance measurements, IR, ESR and electronic spectra. The variable-temperature magnetic susceptibilities of [Gd2( IPHTA) (Mez-phen)4 (ClO4)2] (ClO4)2 complex were measured in the temperature range of 4-300 K and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H = - 2JS1 · S2, giving the exchange parameter J =- 0.19 cm-1 . This result is commensurate with a weak antiferromagnetic spin-exchange interaction between Gd(Ⅲ)-Gd(Ⅲ) ions within the complex.     

Nucleotide hydrolysis in the presence of μ-hydroxo-bridged-cobalt(III) complexes

Abstract

Two cobalt(III) complexes with tridentate ligands, the acyclic diethylenetriamine and macrocyclic 1,4,7-triazacyclononane, were examined as potential catalysts for the hydrolysis of adenosine 5′-triphosphate (ATP). Studies were performed primarily at pH 4.5, where the two complexes were in the binuclear di-μ-hydroxo forms. For both complexes, a rapid initial hydrolysis with first order dependence on the concentration of ATP was observed, k_obs of approximately 0.20 min^?1, followed by very slow hydrolysis. Deuterium isotope studies done in D₂O showed a normal isotope effect with k_H/k_D = 1.8. Spectral investigations and ⁵⁹Co NMR studies indicated that the biphasic nature of the hydrolysis reaction may be due to the formation of a complex in which inorganic phosphate is coordinated to the cobalt, effectively poisoning the catalyst.     

Crystal structure of a μ-oxo-bridged dimeric iron(III) complex

A dimeric [{Fe(5-ClL1)}₂(μ-O)], [H₂-5-ClL1 = N,N′-bis(5-chloro-2-hydroxybenzylidene)-2-methylpropane-1,2-diamine] tetradentate Schiff-base complex, 1, has been synthesized and its crystal structure has been determined by single crystal X-ray diffraction analysis. Structural analysis of complex 1 shows that the complex is a centrosymmetric dimer. Each of the Fe(III) ions has a five-coordinate geometry and one oxygen atom bridges two Fe(III) ions to form a μ-oxo structure. The geometry around iron atom can be described as a square based pyramid with the FeN₂O₂ coordination plane and oxo ligand.     

Some practical comparisons of the efficiency and overloading behaviour of sub-2 μm porous and sub-3 μm shell particles in reversed-phase liquid chromatography

At their optimum flow, sub-3 μm superficially porous or "shell" particles demonstrate similar efficiency to sub-2 μm totally porous particles. The performance of 0.21 cm i.d shell columns is however inferior to those of 0.46 cm i.d., presumably due to packing difficulties. At high flow, shell columns can give flatter Knox curves due to lower operating pressure (half or less of that of the totally porous particles) producing less frictional heating, which combined with the increased thermal conductivity of their non-porous core, gives more efficient heat dissipation. However, the effects of frictional heating for sub-2 μm columns are considerably exaggerated when using pure ACN as mobile phase, as it has a thermal conductivity 3 times less than that of pure water, leading to poorer heat dissipation. Overloading is already problematic for ionised solutes, a group which contains many pharmaceuticals and compounds of clinical relevance, on conventional columns (5 μm porous particles). However, it becomes a more serious issue for both new column types, partially as a result of their very high efficiency, which concentrates the sample as a very narrow band. The sample capacity of one type of shell particle was estimated to be 60% of that of the small totally porous particles, in line with the fraction of the particle volume that is porous. Due to overloading, it is barely possible to achieve perfect peak symmetry for ionised acids or bases with either of these new column types, even by injecting the lowest amounts of sample detectable by UV. While ammonium formate and potassium phosphate buffers gave similar results in overloading studies, use of formic acid as sole mobile phase additive is not recommended for these solutes, as its ionic strength is too low, leading to a catastrophic deterioration in efficiency when sample concentrations of even a few mg/L are injected.     

A novel mixed valent Cu(II)-Cu(I) 2D framework made of a hydrazone and μ-SCN bridged metallacyclic loops cross-linked by μ(3)-SCN chains

A mixed valent copper complex [Cu(II)Cu(I)(L)(μ-SCN)(μ(3)-SCN)](n) (LH = N'-((pyridin-2-yl)methylene)acetohydrazide) has been synthesized and characterized. It is a unique example of a 2D mixed valent Cu(II)-Cu(I) interlinked molecular assembly with a very unusual bridging property of the hydrazone ligand. An extraordinary in situ partial Cu(II)→ Cu(I) reduction is observed in this system at room temperature.