Structural and spectroscopic study on imidazole-copper(II)-N-protected amino acid complexes. Crystal and molecular structure of tetrakis(imidazole)copper(II)bis(N-tosylvalinate)

A pink-red air-stable, crystalline compound of empirical formula [Cu(Im)₄(N-tsval)₂] (Im=imidazole; ts=4-toluenesulfonyl group, hereafter abbreviated as tosyl;N-tsval=N-tosylvalinate monoanion) was synthesized and characterized by means of structural and spectroscopic measurements. The crystal structure of the compound was determined from three-dimensional diffractometer data. The crystals are monoclinic, space groupC2/c, a=18.952 (5),b=12.372 (2),c=17.594 (3) Å,=93.77 (2)°,Z=4. The structure was solved by the heavy-atom method and refined through least-squares calculations toR=0.035 for 2284 observed reflections. The coordination about the copper atom is elongated octahedral, with four imidazole molecules as equatorial ligands and two sulfonic oxygens in axial positions.     

Birefringence studies in non-dipolar liquids

Measurements of the Kerr effect and Cotton—Mouton effect of a series of non-dipolar, axially-symmetric, diamagnetic molecules have been made at 25°C and 632.8 nm. The static orientational correlation functions for these liquids were drawn from depolarised Rayleigh scattering studies and the derived magnetic anisotropies are in good agreement with literature data.     

Di-2-pyridylketone semicarbazone as ligand in metal complexes: synthesis and X-ray crystal structure

A series of complexes of di-2-pyridylketone semicarbazone (Hdips) and Mn(II), Co(II), Co(III), Ni(II) and Cu(II) nitrates were synthesized and characterized by means of IR spectroscopy and for cobalt and nickel by X-ray crystal structures. The results are in agreement with the formulae: Mn(Hdips)₂(NO₃)₂·2H₂O, [Co(Hdips)₂](NO₃)₂·H₂O (I), [Ni(Hdips)₂](NO₃)₂·H₂O (II), Cu(Hdips)(NO₃)₂·2H₂O, [Co(dips)₂](NO₃)·2H₂O (III). The structure of I and II are monoclinic, space groupP2₁/c, with, I,a=15.980(4),b=11.531(2),c=16.170(2)Å;=104.20(2)°,Z=4,R=0.032; II,a=16.109(5),b=11.480(3),c=16.135(6)Å;=104.15(2)°,Z=4,R=0.069. Compound III is also monoclinic, space groupP2₁/c witha=12.173(5),b=15.619(5),c=15.338(8)Å;=111.40(4)°,Z=4,R=0.059. In these complexes the ligand is tridentate via carbonylic oxygen, semicarbazone and pyridine nitrogens forming each two five membered chelate rings with the metal in a distorted octahedral geometry.     

Development of an in situ fiber optic Raman system to monitor hydrothermal vents

The development of a field portable fiber optic Raman system modified from commercially available components that can operate remotely on battery power and withstand the corrosive environment of the hydrothermal vents is discussed. The Raman system is designed for continuous monitoring in the deep-sea environment. A 785 nm diode laser was used in conjunction with a sapphire ball fiber optic Raman probe, single board computer, and a CCD detector. Using the system at ambient conditions the detection limits of SO(4)(2-), CO(3)(2-) and NO(3)(-) were determined to be approximately 0.11, 0.36 and 0.12 g l(-1) respectively. Mimicking the cold conditions of the sea floor by placing the equipment in a refrigerator yielded slightly worse detection limits of approximately 0.16 g l(-1) for SO(4)(-2) and 0.20 g l(-1) for NO(3)(-). Addition of minerals commonly found in vent fluid plumes also decreased the detection limits to approximately 0.33 and 0.34 g l(-1) respectively for SO(4)(-2) and NO(3)(-).     

HPLC-separation of cis and trans monounsaturated fatty acids

Summary The chromatography of monounsaturated fatty acids as their methyl esters on silver nitrate-loaded HPLC-columns has been studied. The separation of cis- and trans-isomers was easily achieved even with columns of low performance. High-performance small-particle-columns treated with silver nitrate separated a large variety of monounsaturated cis and trans positional isomers. The influence of variable silver-loads on the selectivity of the system was studied and a survey of the distribution of positional trans C₁₈₁ isomers in commercial margarines is given.     

New taxane derivatives: synthesis of baccatin[14,1-d]furan-2-one nucleus and its condensation with the norstatine side chain

New taxanes 15 and 18, containing the unsaturated and saturated baccatin[14,1-d]furan-2-one nucleus, respectively, were prepared starting from the readily available 13-oxo-7-Tes-baccatin III (3). Sequential formation of the enolate of 3 and reaction with ethyl glyoxylate gave the 13-oxo-7-Tes-baccatin[14,1-d]-3,4-dehydrofuran-2-one 4. The reduction of 4 can result in the formation of a mixture of compounds corresponding to 13-hydroxy alcohol 5 and 13-enol derivative 6. Both 5 and 6 were transformed into 13-oxo-7-Tes-baccatin[14,1-d]furan-2-one 8 by treatment with a base. Further reduction of 8 gave 13-hydroxy compound 9. Esterification of 6 and 9 with N,O-protected norstatine 12, followed by deprotection, gave the new promising anticancer taxanes 15 and 18, respectively.     

Biocompatible polymers for antibody support on gold surfaces

The elimination or minimization of non-specific protein adsorption from serum is critical for the use of surface plasmon resonance (SPR) sensors for in vitro and in vivo analysis of complex biological solutions. The ultimate goals in this application are to minimize non-specific adsorption of protein and to maximize analyte signal. A reduction of the non-specific protein adsorption from serum of up to 73% compared to carboxymethylated-dextran 500 kDa (CM-dextran) was achieved following a survey of eight biocompatible polymers and 10 molecular weights of CM-dextran. These coatings minimize non-specific adsorption on the sensor while also serving as immobilization matrices for antibody fixation to the probes. Polymers including polysaccharides: CM-dextrans, CM-hyaluronic acid, hyaluronic acid, and alginic acid were investigated. Humic acid, polylactic acid, polyacrylic acid, orthopyridyldisuldfide–polyethyleneglycol–N-hydroxysuccinimide (OPSS–PEG–NHS), and a synthesized polymer; polymethacrylic-acid-co-vinyl-acetate (PMAVA) were also used. The non-specific protein adsorption reduction was measured over a 14 day period at 0 °C for each polymer. Calibration curves using some of these polymers were constructed to show the performance and low detection limit possibilities of these new antibody supports. For many of the polymers, this is the first demonstration of employment as an antibody support for an optical or surface active sensor. CM-dextran is the polymer offering the largest signal for the antigen detection. However, the biocompatible polymers demonstrate a greater stability to non-specific binding in serum. These biocompatible polymers offer different alternatives for CM-dextran.     

Selective synthesis of 14β-amino taxanes

The base induced deprotonation of H-14 of 7-triethylsilyl- (7-TES-) and 7-tert-butoxycarbonyl- (7-BOC-) protected 13-oxo-baccatins gave the corresponding enolates, which were selectively aminated with electrophilic nitrogen donors, such as azodicarboxylates and tosyl azide. In particular, tosyl azide gave the corresponding 7-BOC- and 7-TES-13-oxo-14β-azido-baccatin III. Alternatively, the last compound was prepared via NaN₃ induced azidation of the 13-silyl enol ether of 7-TES-13-oxo-baccatin III under oxidative (cerium ammonium nitrate) conditions. The 13-silyl enol ether was obtained in a multistep process by DBU induced silylation of 7-TES-13-oxo-baccatin III. The 7-TES-13-oxo-14β-azido-baccatin III was used as a key intermediate for the synthesis of a new family of antitumour taxanes containing amino based functional groups at the C-14 position, such as: 14β-azido, 14β-amino, 14β-amino 1, 14-carbamate, 14β-amino 1, 14-thiocarbamate, and 14β-amino N-tert-butoxycarbonyl-1,14-carbamate.     

Structural and spectroscopic properties of N-benzenesulphonylglycine complexes with copper (II)

In this paper are reported structural and spectroscopic properties of (N-benzenesulphonylglycinato) triaquacopper (II) (complex I) and dipotassium bis (N-benzenesulphonylglycinato) cuprate (II) (complex II). The crystals of (I) are monoclinic, space groupP2₁/c,Z=4, with=12.736(4),b=10.292(3),c=10.402(3) Å,=109.41(2)° while those of complex (II) are orthorhombic, space groupPbca, witha=23.333(8),b=10.508(4),c=16.989(5) Å. In both complexes the aminoacid molecules act as bidentatevia carboxylic oxygen and the amide nitrogen atom; in (I) three water molecules complete the coordination to tetragonal pyramidal, while in (II) coordination is square planar, tetrahedrally distorted involving two ligand molecules. The structure (I) was refined to a finalR index of 0.0596 and (II) toR=0.0466.