Search results for "Structure elucidation"
showing 10 items of 23 documents
Automated Diffraction Tomography for the Structure Elucidation of Twinned, Sub-micrometer Crystals of a Highly Porous, Catalytically Active Bismuth M…
2012
Can copper(II) mediate Hoogsteen base-pairing in a left-handed DNA duplex? A pulse EPR study
2010
Pulse EPR spectroscopy is sued to investigate possible structural features of the copper(II) ion coordinated to poly(dG-dC) poly(dG-dC) in a frozen aqueous solution, and the structural change of the polynucleotide induced by the presence of the metal ion. Two different copper species were identified and their geometry explained by a molecular model. According to this model, one species is exclusively coordinated to a single guanine with the N7 nitrogen atom forming a coordinative bond with the copper. In the other species, a guanine and a cytosine form a ternary complex together with the copper ion. A copper crosslink between the N7 of guanine and N3 of cytosine is proposed as the most prob…
Characterization of the interaction of the antifungal and cytotoxic cyclic glycolipopeptide hassallidin with sterol-containing lipid membranes.
2019
Hassallidins are cyclic glycolipopeptides produced by cyanobacteria and other prokaryotes. The hassallidin structure consists of a peptide ring of eight amino acids where a fatty acid chain, additional amino acids, and sugar moieties are attached. Hassallidins show antifungal activity against several opportunistic human pathogenic fungi, but does not harbor antibacterial effects. However, they have not been studied on mammalian cells, and the mechanism of action is unknown. We purified hassallidin D from cultured cyanobacterium Anabaena sp. UHCC 0258 and characterized its effect on mammalian and fungal cells. Ultrastructural analysis showed that hassallidin D disrupts cell membranes, causin…
Corrosion of Heritage Objects: Collagen‐Like Triple Helix Found in the Calcium Acetate Hemihydrate Crystal Structure
2020
Abstract Helical motifs are common in nature, for example, the DNA double or the collagen triple helix. In the latter proteins, the helical motif originates from glycine, the smallest amino acid, whose molecular confirmation is closely related to acetic acid. The combination of acetic acid with calcium and water, which are also omnipresent in nature, materializing as calcium acetate hemihydrate, was now revealed to exhibit a collagen‐like triple helix structure. This calcium salt is observed as efflorescence phase on calcareous heritage objects, like historic Mollusca shells, pottery or marble reliefs. In a model experiment pure calcium acetate hemihydrate was crystallized on the surface of…
Neoclerodanes from Teucrium orientale
2004
Abstract Two new neoclerodane diterpenoids, 6-deacetyl-teucrolivin A (5) and 8beta-hydroxy-teucrolivin B (6), were isolated from the aerial parts of Teucrium orientale, along with four already known neoclerodane diterpenoids, teucrolivin A (1), teucrolivin B (2), teucrolivin C (3) and teucrolivin H (4), previously isolated from Teucrium oliverianum. Their structures were elucidated on the basis of spectroscopic evidence and chemical transformations. Compounds 1-3 were assayed for antifeedant activity against Spodoptera littoralis, S. frugiperda and Heliocoverpa armigera. Teucrolivin A was the most potent of the three compounds tested.
ECS-3: A Crystalline Hybrid Organic-Inorganic Aluminosilicate with Open Porosity
2011
Electrical conductivity and strong luminescence in copper Iodide double chains with isonicotinato derivatives
2015
Direct reactions between CuI and isonicotinic acid (HIN) or the corresponding esters, ethyl isonicotinate (EtIN) or methyl isonicotinate (MeIN), give rise to the formation of the coordination polymers [CuI(L)] with L=EtIN (1), MeIN (2) and HIN (3). Polymers 1-3 show similar structures based on a CuI double chain in which ethyl-, methyl isonicotinate or isonicotinic acid are coordinated as terminal ligands. Albeit, their supramolecular architecture differs considerably, affecting the distances and angles of the central CuI double chains and thereby their physical properties. Hence, the photoluminescence shows remarkable differences; 1 and 2 show a strong yellow emission, whereas 3 displays a…
Quantum Chemical Calculations Predict the Diphenyl Diuranium Compound [PhUUPh] To Have a Stable1Ag Ground State
2006
A Discrete P⋅⋅⋅II⋅⋅⋅P Assembly: The Large Influence of Weak Interactions on the31P NMR Spectra of Phosphane–Diiodine Complexes
2006
Thioethers, except derivatives of [7-R-7,8-C2B9H11] , are more weakly coordinating ligands than phosphanes. This difference is evidenced by the I I distances in the spokeshaped charge-transfer (CT) complexes R2S·I2 and R3P·I2 (Figure 1). The I I distance is sensitive to the strength of the interaction between the s* LUMO orbital on I2 and the HOMO orbital of the donor atom: the stronger the donor, the longer the I I distance. In these spoke CT complexes, the I I distance varies from 3.2 0.2 7 in R3P·I2 adducts [5] to 2.80 0.05 7 in R2S·I2 adducts, [6] indicating the weaker donor character of the thioether group. Whereas extended I2 arrays, spoke adducts of I2, polyiodides, and other structu…
Diorganotin(IV) Complexes of Methyl 2-{[(E)-8-Oxo-5, 8-dihydroquinolin-5-ylidene]hydrazino}benzoate
2012
Three cis-bis{5-[(E)-2-(2-carbomethoxyphenyl)-1- diazenyl]quinolinolato}-diorganotin(IV), R2Sn(L)2, complexes [R = Me (1), Ph (2) and Bz (3)] were synthesized and characterized by 1H-, 13C-, 119Sn- NMR, IR, and 119Sn Mössbauer spectroscopic techniques in combination with elemental analysis. The structure of diphenyltin(IV) complex Ph2Sn(L)2 (2) was determined by single-crystal X-ray crystallography as its tri-benzene solvate. Each complex was found to adopt a distorted cis-R2 octahedral arrangement around the tin atom with the quinolinolato ligands being N,O-chelating; the oxygen atoms are trans to each other. The complexes retain their solid- state structure in non-coordinating solvents as…