A-type procyanidin trimers cinnamtannin B-1, cinnamtannin D-1, lindetannin, and aesculitannin B were studied in terms of their conformation and interaction with four solvents: methanol, acetone, DMSO and pyridine. The experiments demonstrated that for each trimer there are two principal conformers observable in the NMR. The ratio of the conformers (rotamers) depends on the structure of a given ...

We report X-ray crystallographic and 19 F NMR studies of the G-protein RhoA complexed with MgF3- , GDP, and RhoGAP, which has the mutation Arg85'Ala. When combined with DFT calculations, these data permit the identification of changes in transition state (TS) properties. The X-ray data show how Tyr34 maintains solvent exclusion and the core H-bond network in the active site by relocating to rep...

A p-xylyl-based macrocycle L has been synthesized and its binding properties with halides have been investigated by (1)H NMR titrations, single crystal X-ray diffraction analysis, and density functional theory (DFT) calculations. As investigated by (1)H NMR titrations, the ligand preferentially binds a halide in a 1:2 binding mode, with the association constants (in log K2) of 2.82, 2.70, 2.28,...

The novel homochiral metal-organic framework CFA-1 (Coordination Framework Augsburg-1), [Zn5(OAc)4(bibta)3], containing the achiral linker {H2-bibta = 1H,1'H-5,5'-bibenzo[d][1,2,3]triazole}, has been synthesised. The reaction of H2-bibta and Zn(OAc)2·2H2O in N-methylformamide (NMF) (90 °C, 3 d) yields CFA-1 as trigonal prismatic single crystals. CFA-1 serves as a convenient precursor for the sy...

over the past decade, the chemical behavior of flavonoids as antioxidants has become the subject ofintense experimental research. plants represent a main source of natural antioxidants that might serveas leads for the development of novel drugs. malva sylvestris l. known to have various medicinalproperties since several decade ago, were evaluated for their antioxidant compounds ,most of thesebi...

Despite the many protein structures solved successfully by nuclear magnetic resonance (NMR) spectroscopy, quality control of NMR structures is still by far not as well established and standardized as in crystallography. Therefore, there is still the need for new, independent, and unbiased evaluation tools to identify problematic parts and in the best case also to give guidelines that how to fix...

Fragment-based quantum chemical calculations based on our adjustable density matrix assembler (ADMA) are able to calculate NMR chemical shifts even for proteins and protein-protein complexes [1,2]. The agreement between the calculated and experimental chemical shifts in these calculations is, however, highly dependent on including conformational sampling and explicit solvent molecules. On the o...

A new organic compound, 1-(3,5-difluorophenyl)-3-(2-nitrophenyl)urea was synthesized from 2-nitroaniline, 3,5-difluoroaniline and triphosgene in sequential two steps with 92% yield. The product crystallized by the slow evaporation using THF ethyl acetate solvent system to obtain its single crystal. pure crystals were characterized melting point, FT-IR, 1H NMR, 13C NMR MS. structure of compound ...

The conductance of individual 1,4-benzenediamine (BDA)-Au molecular junctions is measured in different solvent environments using a scanning tunneling microscope based point-contact technique. Solvents are found to increase the conductance of these molecular junctions by as much as 50%. Using first principles calculations, we explain this increase by showing that a shift in the Au contact work ...

The long-held “shielding cone” model of the through-space NMR shielding effect of a carbon-carbon double bond predicts only the effect of the magnetic anisotropy of the double bond; it ignores other important contributors to the overall shielding. GIAO-SCF and GIAO-MP2 calculations have been performed on a simple model system, methane moved sequentially above ethene or 2-methylpropene. These ca...