Synthesis and Crystal Structure of a 1-D Chain Zinc（Ⅱ） Coordinated Polymer with N-p-Tolysulfonyl-glutamine

A novel coordination polymer {[Zn(ts-gln)(bipy)]3H2O}n (ts-glnH2=N-p-toly-sulfonyl-glutamine,bipy=2,2-bipyridine) has been prepared and structurally characterized by X-ray diffraction method. It crystallizes in orthorhombic,space group P212121 with a=8.2622(5),b=16.6244(10),c=18.2807(10) ,V=2510.9(3) 3,C22H28N4O8SZn,Mr=573.91,Z=4,Dc= 1.518 g/cm3,μ(MoKa)=1.115 mm-1,F(000)=1192,the final R=0.0262 and wR=0.0662 for 5691 independent reflections with Rint=0.0240. The zinc(Ⅱ) atom is coordinated by N(3) and N(4) atoms of a bipy molecule,two carboxylate O(1) and O(2A) and amino N(1) atoms of ts-gln ligands,resulting in a square-pyramidal geometry. The title complex consists of an infinite zigzag chain of zinc(Ⅱ) ions linked by the carboxylate of N-p-tolysulfonyl-glutamine.     

Role of anions on the crystal structures of copper(II) and zinc(II) complexes of a tunable butterfly cyclophane macrocycle

Three crystal structures of a ditopic cyclophane ligand (L) in which two 1,5,8,12-tetraamine molecules have been attached through methylene spacers to the ortho positions of a benzene ring are reported. The first one (1) corresponds to the tetraprotonated free macrocycle (H4L4+) having two tetrachlorozincate(II) counteranions (C24H54O2N8Cl8Zn2, a = 9.1890(2) A, b = 14.0120(3) A, c = 15.3180(3) A, alpha = 89.2320(7) degrees , beta = 82.0740(6) degrees , gamma = 83.017(1) degrees , Z = 2.00, triclinic, P); the second one (2) is of a binuclear Cu2+ complex having coordinated chloride anions and perchlorate counteranions (C24H58O14N8Cl4Cu2 a = 9.9380(2) A, b = 30.2470(6) A, c = 53.143(1) A, orthorhombic, F2dd, Z = 18), and the third one (3) corresponds to an analogous Zn2+ complex that has been crystallized using triflate as counteranion (C26H(51.2)O(6.6)N8Cl2F6S2Zn2 a = 8.472(5) A, b = 9.310(5), c = 13.745(5) A, alpha = 84.262(5) degrees , beta = 77.490(5) degrees , gamma = 73.557(5) degrees , triclinic, P, Z = 2). The analysis of the crystallographic data clearly shows that the conformation of the macrocycle and, in consequence, the overall architecture of the crystals are controlled by the anions present in the moiety, pi-pi-stacking associations, and hydrogen bonding interactions. The protonation and stability constants for the formation of the Cu2+ and Zn2+ complexes in aqueous solution have been determined potentiometrically in 0.15 mol dm(-3) NaClO4 at 298.1 K. Intramolecular hydrogen bonding defines the protonation behavior of the compound. Positive cooperativity is observed in the formation of the Cu2+ complexes.     

Adiabatic squeezing of molecular wave packets by laser pulses

Strong pulse sequences can be used to control the position and width of the molecular wave packet. In this paper we propose a new scheme to maximally compress the wave packet in a quasistatic way by freezing it at a peculiar adiabatic potential shaped by two laser pulses. The dynamic principles of the scheme and the characteristic effect of the different control parameters are presented and analyzed. We use two different molecular models, electronic potentials modeled by harmonic oscillators, with the same force constants, and the Na(2) dimer, to show the typical yield that can be obtained in compressing the initial (minimum width) molecular wave function.     

Synthesis and Crystal Structure of Cadmium（Ⅱ） Complex [Cd（H2O）（CH3OC6H4COO）2]n

1 INTRODUCTION Cadmium (Ⅱ) complexes have been exten- sively studied from both chemical and structural views, mainly due to the capability of cadmium (Ⅱ) (shared by most d10 metal ions) to adopt different modes of coordination determined by the consideration of size, as well as electrostatic and covalent bonding forces[1]. And the field of coordination polymers has witnessed tremendous growth over the last decade[2]. Many coordination polymeric networks have been shown to posses intere…     

Spectrofluorimetric determination of moxifloxacin in tablets, human urine and serum

A spectrofluorimetric method to determine the antibiotic moxifloxacin is proposed and was applied to pharmaceuticals, human urine and serum. The fluorimetric method allows the determination of 30-300 ng mL-1 moxifloxacin in aqueous solution containing phosphoric acid-phosphate buffer (pH 8.3) with lambda exc = 287 nm and lambda em = 465 nm. Detection and quantification limits were 10 and 30 ng mL-1, respectively, with a relative standard deviation (n = 10) of 2%. This method was applied to the determination of moxifloxacin in three Spanish commercial pharmaceutical formulations. Another variant of the method in micellar medium allows the direct measurement of moxifloxacin in human serum and urine by standard additions. The enhanced fluorescence of moxifloxacin in 8 mM sodium dodecyl sulfate (SDS) solution at pH 4.0 (acetic acid-acetate buffer) for lambda exc = 294 nm and lambda em = 503 nm shows the same linear range as the aqueous method with a 25% lower slope (with detection and quantification limits of 15 and 60 ng mL-1, respectively, and a relative standard deviation of 1.3%), but permits the background fluorescence for urine and serum blanks to be minimized. Hence, sufficient sensitivity is reached to determine therapeutic concentrations of the drug in urine (average recovery 102 +/- 2%) and serum (average recovery 105 +/- 2%) samples.     

Morphological and structural characteristics of diazo dyes at the air-water interface: in situ Brewster angle microscopy and polarized UV/vis analysis

A morphological analysis is presented for Langmuir films of the diazo dyes Sudan 4 (S4), Sudan 3 (S3), and Sudan red (SR), using Brewster angle microscopy. Stable nonmonomolecular structures are formed at the air-water interface denoted as a plateau in the pressure-area isotherms. Monolayer domains are evident by the contrastless image even before the pressure onset, which grow in size until it reached a condensed monolayer. This behavior resembles that of Langmuir films from simple aromatic fatty acids. Films from all the azo dyes display similar features, according to the surface potential isotherms and in situ polarized UV/vis spectroscopy except for the larger area per molecule occupied by S4 and SR. This is attributed to the presence of CH(3) groups that cause steric hindrance modifying the organization of diazo dye molecules at the air-water interface. UV/vis polarized absorption spectroscopy showed preferential orientation of S4 and S3 on the water surface, while SR molecules lie isotropically. For these three diazo dyes, film absorption was negligible at very large areas per molecule, becoming nonzero only at a critical area coinciding with the onset of surface potential. The critical area is ascribed to the formation of a H-bonded network between water molecules and diazo dye headgroups.     

Protein adsorption in fused-silica and polyacrylamide-coated capillaries

The model proteins cytochrome c, myoglobin, ovalbumin, and beta-lactoglobulin were investigated with regard to their adsorption properties on capillaries for electrophoresis. The model compounds were selected to cover a wide range of properties. Cytochrome c is a basic protein (isoelectric point (pI): 9.6; M(r): 11.7 kDa), beta-lactoglobulin is rather acidic (pI: 5.4, M(r): 18.4 kDa), myoglobin was chosen as a neutral reference protein (pI: 6.8-7.4, M(r): 17.8 kDa), and ovalbumin (pI: 5.1, M(r): 45.0 kDa) was selected as a relatively larger analyte. First, the pH dependence of adsorption was investigated for the bare fused silica. A clear correlation to the respective pIs was noted. For myoglobin and ovalbumin, none or negligible adsorption was found above the pI, whereas strong adsorption was noted just below this parameter. Cytochrome c and beta-lactoglobulin already showed distinct adsorption above their pIs. However, none of the proteins showed any significant adsorption more than one pH unit above the pIs. For linear polyacrylamide-coated capillaries, a decreased but not a complete lack of adsorption was observed. Here, pH-dependent adsorption was noted as well. Regeneration of the capillaries by rinsing with buffers containing 200 mM SDS was also investigated. This method was completely successful for myoglobin, but that too for only freshly-adsorbed protein. After a storage time of 24 h and due to the aging of the adsorbate, a sufficient regeneration was no longer possible.     

Pentanuclear Ba(II) complex of a macrocyclic ligand

We report here the first pentanuclear Ba(II) complex of a new tri-aza, tri-oxa macrocycle with two carboxymethyl "arms" pending from two N atoms, H2L2. The crystal structure corresponds to the formula [Ba5(H0.375L2)4(ClO4)(CH3CH2OH)(H2O)2](ClO4)2.5 x 9.5H2O and reveals the presence of four molecules of the ligand surrounding five Ba(II) ions, giving rise to an unusual structure with the metal ions inside a spherical organic cavity.     

Numerical study of colloidal suspensions of soft spherical particles using the network method. 1. DC electrophoretic mobility

The electrophoretic mobility of a spherical particle coated with a uniformly charged permeable membrane and suspended in a general electrolyte solution is calculated numerically. The network simulation method used makes it possible to solve the problem without any restrictions on the values of the parameters such as the membrane thickness, fixed charge density in the membrane, viscous drag in the membrane, number and valence of the ionic species, and electrolyte concentration. The theoretical model used is similar to the one presented by Ohshima (H. Ohshima, J. Colloid Interface Sci. 228 (2000) 190), except for the inclusion in the force balance equation of an additional term corresponding to the force exerted by the liquid on the core of the moving particle. This inclusion is theoretically proven in the limiting case of a nonconducting suspending medium, in which the equation system can be analytically solved. The results obtained coincide with existing analytical expressions when the electrolyte concentration is high, the membrane is thick, and its resistance to the fluid flow is high.     

Exo-metal coordination by a tricyclic [(P(mu-N-2-NC5H4))2(mu-O)]2 dimer in [(P(mu-N-2-NC5H4))2(mu-O)]2(CuCl x (C5H5N)2)4 (2-NC5H4 = 2-pyridyl, C5H5N = pyridine)

The in situ reaction of the phosphazane dimer [CIP(mu-N-2-NC5H4)]2 (2) with CuCl in the presence of CsH5N/H2O gives the title complex [(P(mu-N-2-NC5H4))2(mu-O)]2(CuCl x (C5H5N)2)4 (1), containing a tricyclic [(P(mu-N-2-NC5H4))2(mu-O)]2 ligand which is isoelectronic with species of the type [(P(mu-NR))2NR]2.