Synthesis, spectroscopy, magnetism, and X-ray structures of hexakis(1-(2-chloroethyl)-tetrazole-N4)copper(II) salts

The compounds hexakis(1-(2-chloroethyl)-tetrazole-N4)copper(II) tetrafluoroborate mono(1-(2-chloroethyl)-tetrazole) (1) and hexakis(1-(2-chloroethyl)-tetrazole-N4) copper(II) perchlorate mono(1-(2-chloroethyl)-tetrazole) (2) were obtained from the crystallization of 1-(2-chloroethyl)-tetrazole (teec) with the respective copper salt. The X-ray structures are reported. Both compounds crystallize in the monoclinic space group C2/c for 1: a = 25.754(3) Å, b = 18.162(3) Å, c = 10.298(2) Å = 104.294(7)° and Z = 4 and for 2: a = 25.745(3) Å, b = 18.197(3) Å, c = 10.29355(3) Å = 104.512(10)° and Z = 4. The Cu^II ions are octahedrally surrounded by six teec ligands. One free teec ligand is present in the structures. The Cu–N distances in the centrosymmetrical units are 2.01, 2.04, and 2.39 Å in both compounds, consistent with a Jahn–Teller elongated octahedron. The ligand field spectra of both compounds show a signal in the visible range at about 15.200 cm^–1 and by an EPR spectrum the following values are found: g _| = 2.29 and g = 2.03. The compounds are both paramagnetic and the T value of 0.37 cm^–1 K mol^–1, which is associated with S = 1/2, is what would be expected for a mononuclear Cu^II complex.     

Hybrid ceramic nanosieves: stabilizing nanopores with organic links

Unprecedented hydrothermal stability in functional membranes has been obtained with hybrid organic-inorganic nanoporous materials, enabling long-term application in energy-efficient molecular separation, including dehydration up to at least 150 degrees C.     

Capillary electrophoresis-time of flight-mass spectrometry using noncovalently bilayer-coated capillaries for the analysis of amino acids in human urine

A capillary electrophoresis-time of flight-mass spectrometry (CE-TOF-MS) method for the analysis of amino acids in human urine was developed. Capillaries noncovalently coated with a bilayer of Polybrene (PB) and poly(vinyl sulfonate) (PVS) provided a considerable EOF at low pH, thus facilitating the fast separation of amino acids using a BGE of 1 M formic acid (pH 1.8). The PB-PVS coating proved to be very consistent yielding stable CE-MS patterns of amino acids in urine with favorable migration time repeatability (RSDs <2%). The relatively low sample loading capacity of CE was circumvented by an in-capillary preconcentration step based on pH-mediated stacking allowing 100-nL sample injection (i.e. ca. 4% of capillary volume). As a result, LODs for amino acids were down to 20 nM while achieving satisfactory separation efficiencies. Preliminary validation of the method with urine samples showed good linear responses for the amino acids (R(2) >0.99), and RSDs for peak areas were <10%. Special attention was paid to the influence of matrix effects on the quantification of amino acids. The magnitude of ion suppression by the matrix was similar for different urine samples. The CE-TOF-MS method was used for the analysis of urine samples of patients with urinary tract infection (UTI). Concentrations of a subset of amino acids were determined and compared with concentrations in urine of healthy controls. Furthermore, partial least squares-discriminant analysis (PLS-DA) of the CE-TOF-MS dataset in the 50-450 m/z region showed a distinctive grouping of the UTI samples and the control samples. Examination of score and loadings plot revealed a number of compounds, including phenylalanine, to be responsible for grouping of the samples. Thus, the CE-TOF-MS method shows good potential for the screening of body fluids based on the analysis of endogenous low-molecular weight metabolites such as amino acids and related compounds.     

Synthesis, crystal structure, studies in solution and cytotoxicity of two new fluorescent platinum(II) compounds containing anthracene derivatives as a carrier ligand

Two new cytotoxic fluorescent platinum(II) compounds, cis-[Pt(A9opy)Cl2] (1) and cis-[Pt(A9pyp)(DMSO)Cl2] (2),have been designed, synthesized, and characterized by IR, 1H NMR, and 195Pt NMR spectroscopy; electrospray ionization mass spectrometry (ESI-MS); and single-crystal X-ray diffraction. The carrier ligands selected for thesynthesis of these fluorescent platinum(II) compounds are E-2-[1-(9-anthryl)-3-oxo-3-prop-2-enylpyridine] (abbreviatedas A9opy) and E-1-(9-anthryl)-3-(2-pyridyl)-2-propenone (abbreviated as A9pyp). The compound cis-[Pt(A9opy)Cl2](1) comprises a peculiar cis-platinum(II) organometallic compound, in which the platinum(II) ion is bound to the photoisomerizable carbon-carbon double bond of the carrier ligand. The effects of the metal-ion coordination on the photoisomerization of the carbon-carbon double bond of the ligand have been studied. In contrast, the carrier ligand A9pyp used for the synthesis of the cis-[Pt(A9pyp)(DMSO)Cl2] compound (2) does not undergo such anisomerization process and remains in the E conformation, while coordinated to the platinum(II) ion through the nitrogen of the pyridine ring. In addition to the synthesis and characterization, solution studies of both compounds have also been performed in detail, including NMR and ESI-MS spectroscopy. Moreover, a high degree of cytotoxicactivity of compound 1 was found, as compared to cisplatin and its corresponding platinum-free molecule, in a series of human tumor cell lines. Compound 2 was also found to be highly active against these cell lines but appeared less active compared to the platinum-free molecule.     

Drinfeld modules and torsion in the Chow groups of certain threefolds

Let E B be an elliptic surface defined over the algebraic closureof a finite field of characteristic greater than 5. Let W bea resolution of singularities of E x _B E. We show that the l-adicAbel–Jacobi map from the l-power-torsion in the secondChow group of W to H³(W, _l(2)) _l/_l is an isomorphism for almostall primes l. A main tool in the proof is the assertion thatcertain CM-cycles in fibres of W B are torsion, which is provenusing results from the theory of Drinfeld modular curves.     

Mononuclear Tetraamineplatinum(II) Complexes: Synthesis,Anticancer Activity,DNA Binding,and Cellular Uptake

The synthesis of three bis[(tert‐butoxy)carbonyl]‐protected (tetramine)dichloroplatinum complexes 2a – c of formula cis‐[PtCl₂(LL)] and of their cationic deprotected analogs 3a – c and their evaluation with respect to in vitro cytotoxicity, intramolecular stability, DNA binding, and cellular uptake is reported. The synthesis comprises the complexation of K₂[PtCl₄] with di‐N‐protected tetramines 1a – c to give 2a – c and subsequent acidolysis, yielding 3a – c . The cytotoxicity of the complexes is in direct relation to the length of the polyamine. Complexes 3a – c display a significant higher affinity for CT DNA as well as for cellular DNA in A2780 cells than cisplatin.     

Spreading of polymer molecules on solid surfaces

When a homopolymer adsorbs from dilute solution onto a solid surface it first attaches and then maximises its number of contacts with the substrate by means of a spreading process. Evidence for this spreading process can be obtained from experiments on the adsorption kinetics. We report on a case where the adsorption kinetics depend on the rate at which the polymer was supplied to the surface (a protein adsorbing onto silica). Also, we discuss competitive adsorption experiments in which one kind of chain molecule attempts to displace another one from the surface. In these experiments, the desorption rate of the displaced species reflects the spreading rate of the displacer. When this rate is slower than the supply of displacer molecules, oversaturated layers result that spontaneously eject polymer. We have measured the rate of these displacement-driven desorption processes in various cases and conclude that it depends strongly on the energy of the segment-surface bond. A model involving the diffusion of defects over the surface may account for this finding.     

Coordination chemistry of 5,6,7-trimethyl-[1,2,4]triazolo[1,5-a]pyrimidine with first-row transition-metal salts: Synthesis, spectroscopy and single-crystal structures, with counter-anion dependence of the structures

A variety of new coordination compounds with transition-metal salts and the ligand trimethyl[1,2,4]triazolo[1,5-a]pyrimidine (abbreviated as tmtp) is described, together with several of their 3D crystal structures and spectroscopic and magnetic properties. The compounds were selected based on the coordination ability of the counterion, halide, nitrate, sulfate, thiocyanate and perchlorate. The formed coordination compounds and their coordination numbers were found to be strongly dependent on both the cation and the used counter-anion. The several compounds studied have the following structural formulae: [CuCl₂(tmtp)₂], [CuBr₂(tmtp)₂], [ZnBr₂(tmtp)₂], [Cu(NO₃)₂(tmtp)₂], [CuSO₄(tmtp)₂]₂(H₂O)(MeOH), [Cu(H₂O)(NCS)₂(tmtp)₂], [Zn(NCS)₂(tmtp)₂], [Cd(NCS)₂(tmtp)₂] and [M(H₂O)₂(tmtp)₄](BF₄)₂, in which M = Co, Ni, Zn.The new coordination compounds have been further characterized by NMR, (far-)IR and LF spectra, as well as by C, H, N element analyses, and EPR spectra for the Cu(II) compounds. The coordination around the metal varies from 4 (Zn, Cu), via 5 (Cu) to 6 (for Co, Cu and Cd). The anions usually complete the coordination sphere; only the Co and Zn compounds with the tetrafluoridoborate anions have no coordinated anions, but water ligands complete the octahedral coordination sphere. In the 5-coordinated [Cu(H₂O)(NCS)₂(tmtp)₂] water completes the square pyramid geometry.     

Improved analysis of ladderane lipids in biomass and sediments using high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

Ladderane lipids, containing three or five linearly concatenated cyclobutane moieties, are considered to be unique biomarkers for the process of anaerobic ammonium oxidation, an important link in the oceanic nitrogen cycle. Due to the thermal lability of the strained cyclobutane moieties, the ladderane lipids are difficult to analyze by gas chromatography. A method combining high-performance liquid chromatography coupled to positive ion atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS) was developed for the analysis of the most abundant ladderane lipids, occurring as fatty acids and ether-bound to glycerol. Detection was achieved by selective reaction monitoring of four specific fragmentations per ladderane lipid. Detection limits of 30-35 pg injected on-column and a linear response (r(2) > 0.99) over nearly 3 orders of magnitude were achieved for all compounds. Using this method, these unique ladderane lipids were for the first time identified in a surface sediment from the Gullmarsfjorden, in concentrations ranging from 1.1-5.5 ng/g for the ladderane fatty acids and of 0.7 ng/g for the monoether. It is foreseen that this method will allow the investigation of the occurrence of anaerobic ammonium oxidation in natural settings in much greater detail than before.     

Hepatic lipid composition analysis using 3.0-T MR spectroscopy in a steatotic rat model

Purpose

To investigate the feasibility of in vivo assessment of hepatic lipid composition using 3.0-T proton magnetic resonance spectroscopy (¹H-MRS) in a steatotic rat model and compare it to histopathological and biochemical assessment.

Materials and Methods

Hepatic steatosis was induced by feeding rats with a methionine/choline-deficient (MCD) diet for 1, 2, 3, 5 or 7 weeks (n=5 per group). At the end of the diet period, ¹H-MRS of the liver was performed, and rats were sacrificed for histopathological and biochemical assessment of the liver. Spectra were acquired in a single voxel (1.2 cc) using a point-resolved spectroscopic sequence with TE/TR=35/2000 ms and 64 signal acquisitions. From the MR spectra, peak area ratios were calculated to estimate hepatic lipid composition.

Results

During MCD diet periods, hepatic steatosis significantly increased on histopathology (P<.001). The ¹H-MRS measurements of total hepatic fat content [1.3/(1.3+4.65) ppm] correlated strongly with histological macrovesicular hepatic steatosis (r=0.93, P<.001) and with the biochemical total hepatic fatty acids (r=0.94, P<.001). Total unsaturated fatty acids [TUFA, 5.4/(1.3+4.65) ppm] estimated with ¹H-MRS strongly correlated with the biochemical unsaturated fatty acids (r=0.90, P<.001). Polyunsaturated fatty acids [PUFA, 2.8/(1.3+4.65) ppm] estimated with ¹H-MRS strongly correlated with biochemical PUFA (r=0.91, P<.001). The proportion of total unsaturated fatty acids relative to the amount of total fatty acids (rTUFA, 5.4/1.3ppm) measured with ¹H-MRS strongly correlated with the biochemical amount of unsaturated relative to total hepatic fatty acids (r=0.81, P<.001). The proportion of PUFA relative to the amount of total fatty acids (rPUFA, 2.8/1.3 ppm) measured with ¹H-MRS correlated with the biochemical amount of PUFA relative to total fatty acids (r=0.59, P=0.005,) and with the biochemical amount of omega-6 PUFA relative to total fatty acids (r=0.73, P<.001).PUFA at ¹H-MRS correlated with the histopathologically assessed degree of lobular inflammation in the liver (r=0.57, P=.001).

Conclusion

3.0T ¹H-MRS is able to measure poly- and unsaturated hepatic fatty acids and this strongly correlates with biochemical assessment. This study provides evidence that 3.0-T ¹H-MRS is a noninvasive technique to assess hepatic lipid composition.