Abstract Tridentate NNO donor Schiff base ligand and its mixed ligand zinc(II) complex were synthesized stoichiometrically and characterized by electronic, infrared, mass spectral techniques and elemental analysis. To understand the DNA binding ability, the complex was investigated by various analytical and spectroscopic techniques in presence of calf thymus DNA (CT‐DNA). The binding studies showed that the zinc complex interacts with DNA by groove binding mode with intrinsic binding strength of 2.11 × 10 5 M −1 and with bovine serum albumin the complex showed dynamic quenching attributed for changes in the secondary structure of BSA with efficient interaction. The MCF‐7 cell line studies of the zinc(II) complex with 90.8 μM IC 50 value revealed that the complex is effective for the breast cancer cell line and has a potential as anticancer drug. Furthermore, the tridentate ligand and its mixed ligand zinc complex were screened for antibacterial and antifungal activities, which showed better antimicrobial activity for complex.
The evolution of the porous network in mesoporous TiO2 structures during the calcination induced crystallization process has been studied by transmission electron microscopy, small angle X-ray diffraction and N2 adsorption/desorption techniques. It has been observed that on increasing the calcination temperature, the mesoporous structures undergo phase transition from amorphous to crystalline and their porosity changes from the ordered to the disordered state, generating crystalline fragments or aggregated porous particles. The optimum calcination temperature required for fabricating ordered metal oxide meso-structures using a polymer template has been discussed. The ordered mesoporous TiO2 with a crystalline framework showed prolonged photocatalytic activity and repeated usage as an industrial photodegradation catalyst, advantageous to the commercial nanocrystalline TiO2 Degussa P25. Mechanisms of formation and deformation of mesoporous metal oxide crystalline frameworks are proposed.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Efficient and highly stereoselective oxidation of olefins to cis-diols as the major product is obtained by using biomimetic non-heme FeII catalysts in combination with H2O2.
In this study, an assay to quantify the presence of mercuric ions and methyl mercury by double-stranded DNA containing a poly(dT) sequence was developed using a light switch compound, Ru(phen)2(dppz)2+ (1), which is known to intercalate into double-stranded DNA. Upon treatment with mercuric ions, the metal-to-ligand charge transfer (MLCT) emission derived from the intercalation of 1 was reduced due to the formation of DNA duplexes containing T–Hg2+–T base pairs by the dehybridization of poly(dT)–poly(dA) duplexes at room temperature. As the concentration of Hg2+ was increased, the emission of 1 gradually decreased. This label-free method had a detection limit of 5 nM. Other metal ions, such as K+, Ag+, Ca2+, Mg2+, Zn2+, Mn2+, Co2+, Ni2+, Cu2+, Cd2+, Cr3+, Fe3+, had no significant effect on reducing emission. This emission method can differentiate matched and mismatched poly(dT) sequences based on the dehybridization rate of dsDNA and the rate decreased in the order of T10C·A11 ∼ T10A·A11 > T10G·A11 > T11·A11.
The catalytic effect of [M(2,2'-bipyridine)2(NO3)](NO3) (M(bpy)2, M=Cu(II), Zn(II) and Cd(II)) on the super-coiled and double stranded DNA (scDNA and dsDNA) was examined by electrophoresis and a real-time detection linear dichroism (LD) technique. Although the Cu(bpy)2 complex effectively cleaved both types of DNA, the other two complexes were inactive. This was explained by the electrochemical properties of the metal complexes. The Cu(bpy)2 complex exhibited a redox potential at -0.222V with a peak to peak separation of 0.201V, whereas the other two metal complexes did not undergo any redox reaction. Both electrophoresis and LD measurements revealed the superoxide radical, ·O2(-), to be responsible for DNA cleavage. A kinetic study using the LD technique showed that the cleavage of dsDNA consisted of two first order reactions. The fast reaction is believed to reflect the cleavage of one strand, whereas the slow reaction involves the cleavage of the complementary strand at or near the first cleaved site.
Zn(II) meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (ZnTMPyP) produced a unique linear dichroism (LD) spectrum when forming a complex with Z-form poly[d(G-C)(2)]. The spectrum was characterized by a large positive wavelength-dependent LD signal in the Soret absorption region. The magnitudes of LD in both the DNA and Soret band increased as the [porphyrin]/[DNA base] ratio increased and were larger by 20-40 times compared to the negative LD of the ZnTMPyP bound to B-form poly[d(G-C)(2)] and poly[d(A-T)(2)]. The angles calculated from LD were respectively 49° and 42° for B(x) and B(y) transitions of the porphyrin with respect to the local helix axis of Z-form poly[d(G-C)(2)]. The appearance of the unique LD spectrum for the Z-form poly[d(G-C)(2)] complex was accompanied by a bisignate circular dichroism spectrum in the Soret region, whose magnitude was proportional to the square of the porphyrin concentration, suggesting a stacking interaction between Z-form poly[d(G-C)(2)]-bound ZnTMPyP with other bound ZnTMPyP. From these observations, a conceivable binding mode of ZnTMPyP to Z-form poly[d(G-C)(2)] complex was proposed, in which ZnTMPyP binds at the major groove or across the groove. In contrast with Z-form poly[d(G-C)(2)], ZnTMPyP binds to poly[d(A-T)(2)] in a monomeric manner with the angles of 57° and 59° for the two porphyrin's transition moments with respect to the local polynucleotide helix axis. The polarized spectral properties of ZnTMPyP bound to B-form poly[d(G-C)(2)] coincide with the intercalated nonmetallic TMPyP, namely, a negative CD signal in the Soret band and a negative wavelength-dependent reduced LD signal, with a magnitude larger than that in the DNA absorption region in spite of its axial ligands.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAlkane functionalization at (.mu.-oxo)diiron(III) centersRandolph A. Leising, Jinheung Kim, Miguel A. Perez, and Lawrence Que Jr.Cite this: J. Am. Chem. Soc. 1993, 115, 21, 9524–9530Publication Date (Print):October 1, 1993Publication History Published online1 May 2002Published inissue 1 October 1993https://doi.org/10.1021/ja00074a017Request reuse permissionsArticle Views779Altmetric-Citations137LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (904 KB) Get e-Alertsclose Get e-Alerts
The selective recognition of adenosine with an adenosine-sensitive oligonucleotide is studied via the electrochemical oxidation of guanine bases of the aptamer in solution, leading to a label-free voltammetric aptasensor based on the difference in the oxidative electron transfer rate.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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