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The interaction of pinacyanol chloride(PC) with nucleic acids has been investigated by a series of experiments.Extensive hypochromism,appreciable peak shifts,isosbestic points and new peaks of the product of binding to nucleic acids in the spectra were observed.They showed that the interaction between PC and nucleic acids occurred.The results from absorption spectra of DNA,DNA melting,electrophoresis and fluorescence polarization studies have indicated that PC binds to DNA in nonintercalative way.Consistent with the nonintercalation,the studies of fluorescence titration and absorption titration specified that the binding of PC to nucleic acids occurred by an outside stacking binding,in which nucleic acids served for acting templates,The fact that the new absorption peaks of bound PC at ca,485nm are just close to the absorption bands of Haggregate of PC at high concentrations without DNA further supports the outside stacking binding mode,In addition,other evidence indicated that the interaction between PC and nucleic acids is not purely electrostatic. 相似文献
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On the Formation of Intermetalloid Clusters: Titanocene(III)diammin as a Versatile Reactant Toward Nonastannide Zintl Clusters
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Dr. Christian B. Benda Dr. Markus Waibel Prof. Dr. Thomas F. Fässler 《Angewandte Chemie (International ed. in English)》2015,54(2):522-526
The reactivity of TiCp2Cl2 (d0) towards Zintl clusters was studied in liquid ammonia (Cp=cyclopentadienyl). Reduction of TiIVCp2Cl2 and ligand exchange led to the formation of [TiIIICp2(NH3)2]+, also obtainable by recrystallization of [CpTiIIICl]2. Upon reaction with [K4Sn9], ligand exchange leads to [TiCp2(η1‐Sn9)(NH3)]3?. A small variation of the stoichiometry led to the formation of [Ti(η4‐Sn8)Cp]3?, which cocrystallizes with [TiCp2(NH3)2]+ and [TiCp2(η1‐Sn9)(NH3)]3?. Finally, the large intermetalloid cluster anion [Ti4Sn15Cp5]n? (n=4 or 5) was obtained from the reaction of K12Sn17 and TiCp2Cl2 in liquid ammonia. The isolation of three side products, [K([18]crown‐6)]Cp, [K([18]crown‐6)]Cp(NH3), and [K([2.2]crypt)]Cp, suggests a stepwise elimination of the Cl? and Cp? ligands from TiCp2Cl2 and thus gives a hint to the mechanism of the product formation in which [Ti(η4+2‐Sn8)Cp]3? has a key role. 相似文献
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Shuyu Zhou Congping Li Hao Fu Dr. Jing Cao Prof. Dr. Jian Zhang Prof. Dr. Lei Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(30):6894-6898
In this work we have successfully prepared two lead-doped titanium-oxo clusters with core structures that resemble isolated perovskite PbTiO3 species. In the obtained highly symmetric Pb8Ti7-oxo cluster, the central TiO6 octahedra are orthogonally extended to adjacent octahedra through corner-sharing and the eight dopant lead ions form a cubic arrangement, making it the first molecular model of perovskite PbTiO3. Moreover, the clusters readily dissolved in chloroform and showed high solution stability, as confirmed by MALDI-TOF MS measurements. Based on such solution processability, they can be easily spin-coated to form homogeneous films, which were employed as electron-transport materials in perovskite solar cells to give an average power conversion efficiency of around 15 % and improved device stability. This newly developed bottom-up cluster assembly method provides an efficient approach to the construction of atomically precise models of perovskite metal oxides as well as potential molecular tools to extend their applications. 相似文献
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Cover Picture: On the Formation of Intermetalloid Clusters: Titanocene(III)diammin as a Versatile Reactant Toward Nonastannide Zintl Clusters (Angew. Chem. Int. Ed. 2/2015)
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Dr. Christian B. Benda Dr. Markus Waibel Prof. Dr. Thomas F. Fässler 《Angewandte Chemie (International ed. in English)》2015,54(2):365-365
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铁结合蛋白(Fbp)是致病菌获取Fe3+的关键蛋白。本文采用氨三乙酸(H3NTA)和硝酸铋反应制备BiNTA.2H2O,并运用元素分析、NMR等手段进行表征。通过在大肠杆菌中克隆表达和分离纯化出奈瑟氏淋病双球菌的Fbp,测定不同计量比nBiNTA/napo-Fbp下反应的紫外可见光谱,确定BiNTA与apo-Fbp的反应为一级反应,反应速率常数约为(0.175±0.064)min-1(10 mmol.L-1 Hepes/HPO42-pH 7.4缓冲溶液,310 K)。NH4BiCit与apo-Fbp的反应也为一级反应,反应速率与BiNTA相近。Bi3+与apo-Fbp的饱和结合计量比为1∶1,形成三元配合物Fbp-Bi-NTA的结合常数(lgK)为(21.43±0.20),形成Fbp-Bi-Cit的结合常数(lgK)为(16.03±0.03)。实验结果表明,致病菌中运输Fe3+的蛋白铁结合蛋白可作为含铋抗菌药物的潜在靶分子。 相似文献
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Reversible Binding of Solvent to Naked PbII Centers in Unusual Homoleptic Alkynyl‐Based Pt2Pb2 Clusters
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Dr. Jesús R. Berenguer Dr. Julio Fernández Dr. Belén Gil Prof. Elena Lalinde Dr. Sergio Sánchez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2574-2584
We report a series of luminescent sandwich‐type clusters [Pt2Pb2(C≡CR)8] (R=Tol, 1 ; C6H4OMe‐3, 2 ; C6H4OMe‐4, 3 ) with a dynamic Pt2Pb2 metallic core, which is key to their intriguing stimuli‐responsive photophysical properties. The solvent‐free solids 1 – 3 display an orange emission ascribed to charge transfer from Pt–alkynyl fragments to a delocalized orbital with mixed Pt2Pb2/C≡CR nature, with a predominant lead contribution and Pb???Pb bonding character (3MLCCT/3IL). They exhibit mechanical, color, and luminescence changes that are reversible and perceivable with the naked eye, which are attributed to small inter‐ and intramolecular structural modifications induced by gentle grinding. Interestingly, 1 and 2 also exhibit remarkable and fast reversible vapochromic responses to donor solvent vapors (acetone, THFMe‐2: yellow; NCMe: green, vs. dry solids: orange). The structures of 1(acetone)2 ?2(Me2CO), 2 ( acetone ) 3 , and 2 ( THFMe ‐ 2 ) 2 allow the vapochromic responses to be ascribed to the fast creation/disruption of solvate clusters [Pt2Pb2(C≡CR)8Sx] (x≥2), with concomitant electronic and geometrical modifications within the Pt2Pb2 core, which are easily accessible through a slight change in the stereochemical activity of the lone pair. The binding of one (or two) solvent molecules to Pb2+ increases the Pb???Pb separation in the metallic core, causing a destabilization of the target orbital and larger energy gaps of the transitions. All the solvates exhibit remarkable rigidochromism upon a decrease in temperature, which is also associated with the gradual increase in the transannular Pb???Pb separation, as revealed by X‐ray crystallography of 1 ( acetone ) 2 at different temperatures. Investigation of the crystal lattice of 1 ?CH2Cl2 and 3 ?2 CH2Cl2 further suggests that the lack of vapor stimuli response of complex 3 could be attributed to the presence of competitive additional secondary intermolecular Pb???O(OMe) contacts, which give rise to a more compact network built up from extended chains of clusters. 相似文献
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Xixi Wang Jiankai Shan Wei Liu Jing Li Hongwei Tan Xichen Li Guangju Chen 《Molecules (Basel, Switzerland)》2021,26(13)
In this work, we have investigated the binding conformations of the substrate in the active site of 5-HIU hydrolase kpHIUH and its catalytic hydrolysis mechanism. Docking calculations revealed that the substrate adopts a conformation in the active site with its molecular plane laying parallel to the binding interface of the protein dimer of kpHIUH, in which His7 and His92 are located adjacent to the hydrolysis site C6 and have hydrogen bond interactions with the lytic water. Based on this binding conformation, density functional theory calculations indicated that the optimal catalytic mechanism consists of two stages: (1) the lytic water molecule is deprotonated by His92 and carries out nucleophilic attack on C6=O of 5-HIU, resulting in an oxyanion intermediate; (2) by accepting a proton transferred from His92, C6–N5 bond is cleaved to completes the catalytic cycle. The roles of His7, His92, Ser108 and Arg49 in the catalytic reaction were revealed and discussed in detail. 相似文献
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Bandgap Engineering of Titanium–Oxo Clusters: Labile Surface Sites Used for Ligand Substitution and Metal Incorporation
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Jin‐Xiu Liu Mei‐Yan Gao Dr. Wei‐Hui Fang Prof. Dr. Lei Zhang Prof. Dr. Jian Zhang 《Angewandte Chemie (International ed. in English)》2016,55(17):5160-5165
Through the labile coordination sites of a robust phosphonate‐stabilized titanium–oxo cluster, 14 O‐donor ligands have been successfully introduced without changing the cluster core. The increasing electron‐withdrawing effect of the organic species allows the gradual reduction of the bandgaps of the {Ti6} complexes. Transition‐metal ions are then incorporated by the use of bifunctional O/N‐donor ligands, organizing these {Ti6} clusters into polymeric structures. The coordination environments of the applied metal ions show significant influence on their visible‐light adsorption. Both the above structural functionalizations also tune the photocatalytic H2 production activities of these clusters. This work provides a systematic bandgap engineering study of titanium–oxo clusters, which is important not only for their future photocatalytic applications, also for the better understanding of the structure–property relationships. 相似文献
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Mei-Yan Gao Prof. Lei Zhang Prof. Jian Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(44):10450-10455
A range of polyoxotitanium clusters (PTCs) was constructed by tuning the type of acid (inorganic and organic) in alcoholic solvents, from Ti4, Ti6, Ti9, Ti11, to Ti16. After removing the tBuOH solvent, giant carboxylate-stabilized Ti44-oxo clusters in which propionic acid serves as both ligand and solvent were ultimately obtained. The four labile sites in the Ti44 cluster core can be occupied by two formate and two propionate anions ( PTC-165 ) or a pair of glutarate ( PTC-166 ) or 3-methylglutarate anions ( PTC-167 ). According to the synthesis of PTC-155 to PTC-167 , the propionic acid solvent plays a crucial role in the construction of giant Ti oxo clusters. Their one-pot yields, which readily reached up to 8.75 g for PTC-165 and 9.96 g for PTC-166 , proved the feasibility of large-scale preparation. More interestingly, the obtained Ti44-oxo clusters are almost completely surrounded by carboxylate ligands, which allow them to retain crystalline stability in air for about three weeks and in either acidic or basic aqueous solution over a wide pH range for at least 6 h. In addition, PTC-165 and PTC-166 exhibit excellent UV photocurrent response and reversible photochromic effect. This work provides a systematic approach for constructing high-nuclearity and stable PTCs on a large scale, which is significant for future applications of PTC-based photochemical devices. 相似文献
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It is well known that proflavine binds to DNA. Here we investigate the binding mode of proflavine to native DNA using absorption, circular dichroism (CD), and linear dichroism (LD) spectroscopy as well as by fluorescence techniques. The observed changes of proflavine upon complexation with DNA can be summarized as a red shift and hypochromism in the absorption spectrum. The negative LDr in the proflavine absorption region has a magnitude comparable to or larger than that of the DNA absorption region, confirming the intercalative binding mode of proflavine to DNA. Saturation of the LD spectrum in the proflavine absorption region at R = 0.25 and a decrease in the fluorescence intensity provide further evidence of intercalation. Furthermore, the coupling of electric transition of intercalated proflavine is observed. Although proflavine has been reported to position itself along the DNA stem at high [proflavine]/[DNA base] ratios, the spectral characteristics, which include a clear isosbestic point in the absorption spectrum and proportionality in the LD magnitude in the proflavine absorption region, do not show any possibility of exterior binding. 相似文献
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Kinga I. Leszczyska Volker Huch Carsten Prsang Jan Schwabedissen Raphael J. F. Berger David Scheschkewitz 《Angewandte Chemie (International ed. in English)》2019,58(15):5124-5128
Small‐ to medium‐sized clusters occur in various areas of chemistry, for example, as active species of heterogeneous catalysis or as transient intermediates during chemical vapor deposition. The manipulation of stable representatives is mostly limited to the stabilizing ligand periphery, virtually excluding the systematic variation of the property‐determining cluster scaffold. We now report the deliberate expansion of a stable unsaturated silicon cluster from six to seven and finally eight vertices. The consecutive application of lithium/naphthalene as the reducing agent and decamethylsilicocene as the electrophilic source of silicon results in the expansion of the core by precisely one atom with the potential of infinite repetition. 相似文献
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The signatures of nanosolvation on the one‐ and two‐dimensional (1D and 2D) IR spectra of a proton‐transfer mode in a hydrogen‐bonded complex dissolved in polar solvent molecule nanoclusters of varying size are elucidated by using mixed quantum–classical molecular dynamics simulations. For this particular system, increasing the number of solvent molecules successively from N=7 to N=9 initiates the transition of the system from a cluster state to a bulk‐like state. Both the 1D and 2D IR spectra reflect this transition through pronounced changes in their peak intensities and numbers, but the time‐resolved 2D IR spectra also manifest spectral features that uniquely identify the onset of the cluster‐to‐bulk transition. In particular, it is observed that in the 1D IR spectra, the relative intensities of the peaks change such that the number of peaks decreases from three to two as the size of the cluster increases from N=7 to N=9. In the 2D IR spectra, off‐diagonal peaks are observed in the N=7 and N=8 cases at zero waiting time, but not in the N=9 case. It is known that there are no off‐diagonal peaks in the 2D IR spectrum of the bulk version of this system at zero waiting time, so the disappearance of these peaks is a unique signature of the onset of bulk‐like behavior. Through an examination of the trajectories of various properties of the complex and solvent, it is possible to relate the emergence of these off‐diagonal peaks to an interplay between the vibrations of the complex and the solvent polarization dynamics. 相似文献