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排序方式: 共有260条查询结果,搜索用时 15 毫秒
191.
192.
Darko P. Aanin Sanja Skaro Bogojevic Franc Perdih Tina P. Andrejevi Dusan Milivojevic Ivana Aleksic Jasmina Nikodinovic-Runic Biljana . Glii Iztok Turel Milo I. Djuran 《Molecules (Basel, Switzerland)》2021,26(7)
Three new silver(I) complexes [Ag(NO3)(tia)(H2O)]n (Ag1), [Ag(CF3SO3)(1,8-naph)]n (Ag2) and [Ag2(1,8-naph)2(H2O)1.2](PF6)2 (Ag3), where tia is thianthrene and 1,8-naph is 1,8-naphthyridine, were synthesized and structurally characterized by different spectroscopic and electrochemical methods and their crystal structures were determined by single-crystal X-ray diffraction analysis. Their antimicrobial potential was evaluated against four bacterial and three Candida species, and the obtained results revealed that these complexes showed significant activity toward the Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and the investigated Candida species with minimal inhibitory concentration (MIC) values in the range 1.56–7.81 μg/mL. On the other hand, tia and 1,8-naph ligands were not active against the investigated strains, suggesting that their complexation with Ag(I) ion results in the formation of antimicrobial compounds. Moreover, low toxicity of the complexes was detected by in vivo model Caenorhabditis elegans. The interaction of the complexes with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was studied to evaluate their binding affinity towards these biomolecules for possible insights into the mode of antimicrobial activity. The binding affinity of Ag1–3 to BSA was higher than that for DNA, indicating that proteins could be more favorable binding sites for these complexes in comparison to the nucleic acids. 相似文献
193.
The NMR coupling constants ((3)J(H(N), H(alpha))) of dipeptides indicate that the backbone conformational preferences vary strikingly among dipeptides. These preferences are similar to those of residues in small peptides, denatured proteins, and the coil regions of native proteins. Detailed characterization of the conformational preferences of dipeptides is therefore of fundamental importance for understanding protein structure and folding. Here, we studied the conformational preferences of 13 dipeptides using infrared and Raman spectroscopy. The main advantage of vibrational spectroscopy over NMR spectroscopy is in its much shorter time scale, which enables the determination of the conformational preferences of short-lived states. Accuracy of structure determination using vibrational spectroscopy depends critically on identification of the vibrational parameters that are sensitive to changes in conformation. We show that the frequencies of the amide I band and the A12 ratio of the amide I components of dipeptides correlate with the (3)J(H(N), H(alpha)). These two infrared vibrational parameters are thus analogous to (3)J(H(N), H(alpha)), indicators for the preference for the dihedral angle phi. We also show that the intensities of the components of the amide III bands in infrared spectra and the intensities of the skeletal vibrations in Raman spectra are indicators of populations of the P(II), beta, and alpha(R) conformations. The results show that alanine dipeptide adopts predominantly a PII conformation. The population of the beta conformation increases in valine dipeptides. The populations of the alpha(R) conformation are generally small. These data are in accord with the electrostatic screening model of conformational preferences. 相似文献
194.
195.
Franc Forstneric Christine Laurent-Thié baut 《Transactions of the American Mathematical Society》2008,360(1):307-329
We explore connections between geometric properties of the Levi foliation of a Levi-flat hypersurface and holomorphic convexity of compact sets in , or bounded in part by . Applications include extendability of Cauchy-Riemann functions, solvability of the -equation, approximation of Cauchy-Riemann and holomorphic functions, and global regularity of the -Neumann operator.
196.
Dr. Yang Liu Dr. Stefan G. Resch Haowei Chen Dr. Sebastian Dechert Dr. Serhiy Demeshko Dr. Eckhard Bill Prof. Dr. Shengfa Ye Prof. Dr. Franc Meyer 《Angewandte Chemie (International ed. in English)》2023,62(10):e202215840
A flexible macrocyclic ligand with two tridentate {CNC} compartments can host two Cu ions in reversibly interconvertible states, CuICuI ( 1 ) and mixed-valent Cu1.5Cu1.5 ( 2 ). They were characterized by XRD and multiple spectroscopic methods, including EPR, UV/Vis absorption and MCD, in combination with TD-DFT and CASSCF calculations. 2 features a short Cu⋅⋅⋅Cu distance (≈2.5 Å; compared to ≈4.0 Å in 1 ) and a very high delocalization energy of 13 000 cm−1, comparable to the mixed-valent state of the biological CuA site. Electron self-exchange between 1 and 2 is rapid despite large structural reorganization, and is proposed to proceed via a sequential mechanism involving an active conformer of 1 , viz. 1′ ; the latter has been characterized by XRD. Such electron transfer (ET) process is reminiscent of the conformationally gated ET proposed for biological systems. This redox couple is a unique pair of flexible dicopper complexes, achieving fast electron self-exchange closely related to the function of the CuA site. 相似文献
197.
198.
199.
Eleonora Ferretti Sebastian Dechert Serhiy Demeshko Max C. Holthausen Franc Meyer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1719-1723
Reductive coupling of nitric oxide (NO) to give N2O is an important reaction in the global nitrogen cycle. Here, a dinickel(II) dihydride complex 1 that releases H2 upon substrate binding and serves as a masked dinickel(I) scaffold is shown to reductively couple two molecules of NO within the bimetallic cleft. The resulting hyponitrite complex 2 features an unprecedented cis‐[N2O2]2? binding mode that has been computationally proposed as a key intermediate in flavodiiron nitric oxide reductases (FNORs). NMR and DFT evidence indicate facile rotational fluxionality of the [N2O2]2? unit, which allows to access an isomer that is prone to N2O release. Protonation of 2 is now found to trigger rapid N2O evolution and formation of a hydroxido bridged complex, reminiscent of FNOR reactivity. This work provides fundamental insight into the biologically relevant reductive coupling of two NO molecules and the subsequent trajectory towards N2O formation at bimetallic sites. 相似文献
200.
Uttam Chakraborty Serhiy Demeshko Franc Meyer Axel JacobivonWangelin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3504-3508
While the coordination chemistry of monometallic complexes and the surface properties of extended metal particles are well understood, the control of metal nanocluster formation has remained challenging. The isolation of discrete metal clusters provides an especially rare snapshot at the nanoscale of cluster growth. The synthesis and full characterization of the first early‐transition‐metal alkynyl cubane and the first μ3‐alkynyl Mn3 motif are reported. 相似文献