Synthesis and properties of siRNAs containing 5′-amino-2′,5′-dideoxy-2′α-fluororibonucleosides

Short interfering RNAs (siRNAs) containing P3′→N5′ phosphoramidate linkages were successfully synthesized by introducing 2′-deoxy-2′-fluororibonucleoside and 5′-amino-2′,5′-dideoxy-2′α-fluororibonucleoside in succession. It was found that the introduction of 5′-amino-2′,5′-dideoxy-2′α-fluororibonucleosides into siRNAs improved the nuclease-resistant properties of the siRNAs without loss of their silencing efficacy.     

Synthesis,characterization, crystal structure,and DNA binding of two copper(II)–hydrazone complexes

Two new Cu(II)–hydrazone complexes, [Cu(L)(Hbpe)ClO₄]·ClO₄·[Cu(L)Cl] (1) and [Cu(HL)₂]·1.5ClO₄·0.5OH (2) (where HL?=?(E)-N′-(1-(pyridine-2-yl)ethylidene)benzohydrazide and bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene), have been synthesized and characterized by physicochemical methods. The structures of the complexes have been established by single-crystal X-ray diffraction direct methods, which reveal that the metal ions have distorted square-pyramidal and square-planar geometries in 1, and a distorted octahedral geometry in 2. DNA binding of HL, 1, and 2, performed by UV–vis titration in tris-buffer medium, yielded binding constants, which are 9.5 × 10³, 1.88 × 10⁴, and 4.66 × 10⁴ M^?1, respectively. Viscosity measurements suggest a surface or groove-binding mode of interaction between CT-DNA with HL, 1, and 2.     

Novel plastoquinone analogs containing benzocaine and its analogs: structure‐based design,synthesis, and structural characterization

Introducing new biologically active organic molecules or their analogs into the pharmaceutically important molecules significantly enables the discovery and development of the medicines that improve the health of patients. Chemical synthesis has a key role in pharmaceutical research and development, aiming to design and build molecules with the essential biological activity needed in drugs. For that reason, herein, three series of novel PQ analogs (the nonhalogenated (PQ1-6) and the halogenated PQ analogs (BrPQ1-6 and ClPQ1-6)) containing benzocaine and its analogs were designed and synthesized starting from the commercially available dimethylhydroquinone (1) with benzocaine and its analogs. The structures of all synthesized analogs were characterized by using spectroscopic methods. The in vitro antibacterial and antifungal activities were evaluated for the PQ analogs.

     

Synthesis and crystal structure study of 2′-Se-adenosine-derivatized DNA

The selenium derivatization of nucleic acids is a novel and promising strategy for 3D structure determination of nucleic acids.Selenium can serve as an excellent anomalous scattering center to solve the phase problem,which is one of the two major bottlenecks in macromolecule X-ray crystallography.The other major bottleneck is crystallization.It has been demonstrated that the incorporated selenium functionality at the 2′-positions of the nucleosides and nucleotides is stable and does not cause significant st...     

Synthesis,spectral characterization,and anticancer activity of 6-methylpyridine-2-carbaldehdyethiosemicarbazone and its complexes; crystal structure and DFT calculations of [Pd(mpyptsc)Cl]·DMSO

Synthesis and characterization of new complexes of 6-methylpyridine-2-carbaldehydethiosemicarbazone (Hmpytsc) and 6-methylpyridine-2-carbaldehyde-N(4)-phenylthiosemicarbazone (Hmpyptsc) with [VO₂L], [Zn(HL)Cl₂], [Ru(PPh₃)₂L₂], and [MLCl] (M(II)?=?Pd, Pt; HL?=?Hmpytsc, Hmpyptsc) are reported. Their structures are discussed on the basis of IR, Raman, UV–vis, NMR (¹H, ¹³C, and ³¹P), and mass spectroscopic data, as well as elemental analysis and molar conductivity. In the X-ray crystal structure of the square-planar [Pd(mpyptsc)Cl]·DMSO, mpyptsc^? is coordinated to Pd(II) in a tridentate manner through pyridyl N, azomethine N, and thiol S, and the fourth coordination site is occupied by a chloride. A theoretical study on [Pd(mpyptsc)Cl]·DMSO was undertaken through DFT conformational analysis. The in vitro cytotoxic activity has been evaluated against human colon cancer (HCT116) and prostate cancer (DU145) cell lines. Hmpyptsc and [Zn(Hmpyptsc)Cl₂] were most active with mean IC₅₀ values of 3.32 and 2.60 (HCT116), and 3.60 and 3.10 (DU145)?μM, respectively.     

Synthesis, spectrophotometric pH titrations and DNA binding properties of a cyclometalated iridium(III) complex of tetrapyrido[3,2-a:2′,3′-c:3″,2″-h:2?,3?-j]phenazine

A new cyclometalated iridium(III) complex [Ir(ppy)₂(tpphz)]Cl {Hppy = 2-phenylpyridine and tpphz = tetrapyrido[3,2-a:2′,3′-c:3″,2″-h:2?,3?-j]phenazine} has been synthesized and characterized. The pH effects on UV-vis absorption spectra have been studied, and three ground-state acidity ionization constant values have been derived. The calf thymus (ct) DNA binding properties of the complex have also been investigated with UV-vis absorption spectrophotometric titrations, DNA competitive binding with ethidium bromide, DNA melting experiments, viscosity measurements, and density functional theory calculations. The complex was demonstrated to act as a DNA intercalator with a binding constant of (9.29 ± 1.26) × 10⁵ M⁻¹ more than one order of magnitude greater than that previously reported for DNA intercalator of [Ir(ppy)₂(dppz)]⁺.     

Synthesis,crystal structure,and magnetic characteristics of chiral cyanide-bridged Fe–Cu complex

Based on the building blocks, trans-dicyanide Fe(III) precursor and chiral amine Cu(II) compound, the chiral cyanide-bridged heterometallic Fe(III)–Cu(II) complex with the formula {[Cu(R/R-Chxn)₂Fe(bpmb)·(CN)₂][Fe(bpmb)(CN)₂]}·CH₃OH·H₂O (1) [bpmb^2– = 1,2-bis(pyridine-2-carboxamido)-4-methylbenzenate, R,R-Chxn = R,R-1,2-diaminocyclohexane] has been synthesized and characterized by elemental analysis, IR spectra and X-ray analysis. The latter revealed that the complex contained the cyanide-bridged cationic binuclear entity and free anionic cyanide building block. The complex demonstrated weak ferromagnetic coupling between neighboring Fe(III) and Cu(II) ions via the bridging cyanide group.     

Pronounced effects of grinding on rates of intramolecular electron transfer in mixed-valence 1′,2′,1?,2?-tetranaphthylmethyl- and 1′,3′,1?,3?-tetranaphthylmethyl-biferrocenium triiodides

The X-ray structural determinations of the neutral 1′,2′,1?,2?-tetranaphthylmethylbiferrocene and the mixed-valence 1′,3′,1?,3?-tetranaphthylmethylbiferrocenium triiodide have been determined. Our Mössbauer measurements for mixed-valence 1′,2′,1?,2?-tetranaphthylmethylbiferrocenium triiodide (1) and 1′,3′,1?,3?-tetranaphthylmethylbiferrocenium triiodide (2) indicate that the intramolecular electron-transfer rates in 1 and 2 are quite sensitive to the environmental perturbations caused by the grinding of sample. An interesting finding is that the Mössbauer results indicate that the unground diffusing sample of 1 is valence delocalized on the Mössbauer time scale above 180 K. However, the ground diffusing sample of 1 exhibits a Mössbauer spectrum characteristic of a valence-trapped cation which remains valence-trapped electronic state even at 300 K. The effects of grinding of samples are also observed in the EPR measurements.     

Synthesis,characterization, and systematic structure–property investigation of a series of carbazole–thiophene derivatives

Russian Journal of General Chemistry - A series of carbazole–thiophene oligomers linked at the 3,6-positions of the carbazole fragment of 4,4′-bis(carbazol-9-yl)biphenyl (CBP) and...     

Synthesis,crystal structure,and characterization of energetic complex Pb(ATZ)(phen)2 · 3H2O

A new energetic complex, Pb(ATZ)(phen)₂·3H₂O (1) (ATZ = 5,5′-azotetrazolate), was synthesized and characterized by single crystal X-ray diffraction. Crystal data: monoclinic, P2(1)/n space group, a = 8.4545(1) Å, b = 25.846(2)Å, c = 13.096(2)Å, and β = 102.873(2)°. In addition, elemental analysis, IR, and thermogravimetric analysis are presented. Furthermore, the complex was also explored as an additive to promote thermal decomposition of ammonium perchlorate.     

Synthesis,structure, and spectroscopic characterization of a 2-D organic–inorganic hybrid CuII–ErIII heterometallic arsenotungstate

An organic–inorganic hybrid Cu^II–Er^III heterometallic arsenotungstate Na₃[Cu(en)₂(H₂O)][Cu(en)₂]_1.5[H₃Er(α-AsW₁₁O₃₉)₂]·4H₂O (1) (en = ethylenediamine) has been hydrothermally synthesized and structurally characterized by elemental analyses, IR and UV spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and single-crystal X-ray diffraction. 1 displays an organic–inorganic 2-D sheet structure constructed by sandwich-type [H₃Er(α-AsW₁₁O₃₉)₂]⁸⁻ fragments and [Cu(en)₂]²⁺ connectors. From the topological viewpoint, if the [H₃Er(α-AsW₁₁O₃₉)₂]⁸⁻ fragments are viewed as 3-connected nodes and [Cu(en)₂]²⁺ connectors are considered as linkers, the 2-D sheet can be simplified into a 2-D (6,3)-network topology.     

Preparation,characterization and crystal structure of N,N-dimethylanilinium β-octamolybdate dihydrate

N,N-dimethylanilinium β-ocatmolybdate dihydrate has been synthesized in acidic aqueous solution. The compound has been identified by using TG, DTG, IR and ¹H NMR techniques. It crystallizes in the triclinic system, space group PĪ, Z = 1, a = 11.755(3) Å, b = 11.836(5) Å, c = 10.498(2) Å, α = 105.29(2)°, β = 81.56(3)°, γ = 115.24(3)°, V = d1273.4(8) Å, D_o = 2.23(1) Mg m⁻³, D_x = 2.23 Mg m⁻³, R = 0.029 and R₂ = 0.032 for 5259 observed reflexions. Two crystallographically independent [C₈H₁₂N]⁺ cations, one water molecule and one centrosymmetric β-octamolybdate polyanion are present in the asymmetric unit. Hydrogen bonds of types NH ···O and OH···O seem to stabilize the structure.     

The total synthesis and structure–activity relationships of a highly cytotoxic depsipeptide kulokekahilide-2 and its analogs

We successfully completed the total synthesis of kulokekahilide-2, a cytotoxic depsipeptide from the Cephalaspiedean mollusk Phillinopsis speciosa. We have revised the absolute stereochemistry of kulokekahilide-2 to 21-l-Ala, 24-d-MePhe, 37-l-Ile, 43-d-Ala, 15-d-Hica, and 5S,6S,7S-Dtda. We also investigated the cause of the mis-assignment of the configuration in the originally proposed kulokekahilide-2 and concluded that methanolysis using MeONa caused partial racemization, which led to the mis-assignment. The structure–activity relationships of kulokekahilide-2 and its analogs indicate the importance of an l-amino acid at position 21.     

Synthesis and characterization of CeO<Subscript>2</Subscript>–graphene composite

The synthesis and characterization of graphite oxide (GO), graphene (GS), and the composites: GS–CeO₂ and GO–CeO₂ are reported. This synthesis was carried out by mixing aqueous solutions of CeCl₃·7H₂O and GO, which yields the oxidized composite GO–CeO₂. GO–CeO₂ was hydrothermally reduced with ethylene glycol, at 120 °C, yielding the reduced composite GS–CeO₂. GO, GS ,and the composites with CeO₂ were characterized by CHN, TG/DTG, BET, XRD, SEM microscopy, FTIR, and Raman spectroscopy. The estimation of crystallite size of CeO₂ anchored on GO and on GS by Raman, XRD, and SEM agreed very well showing diameters about 5 nm. The role of particles of CeO₂ coating carbon sheets of GO and GS was discussed.     

Synthesis, characterization and crystal structures of manganese (Ⅱ) complexes containing nitronyl nitroxide and its reduced derivative

Two novel adducts of formula Mn(hfac)2( NITPhCl )2 (1) and [Mn(hfac)2(IMHPhCl)]2(NIT-PhCl)·0.5H2O (2), where hfac = hexafluoroacetylacetonate, NITPhCl = 2-(3-chlorophenyl)-4,4,5,5-tetram-ethylimidazolyl-1-oxyl-3-oxide, IMHPhCl = 2-(3-chlorophenyl)-4, 4, 5, 5-tetramethylimidazolyl-3-oxide, have been prepared by the reaction of Mn(hfac)2·2H2O with NITPhCl. Compound 1 is triclinic, space group P-1with a = 1.3003(3) nm, 6 = 1.3138(3) nm,c = 1.4931 (3) nm, α = 83.74(3)°, β = 77.77(3)°, γ = 60.59(3)°, V=2.171(1)nm3, Z = 2. Compound 2 is triclinic, space group P-1 with a = 1.2994(3) nm, b = 1.4841(3) nm, c = 2.1031 (4) nm, a = 92.30(3)° ,p = 98.68(3)°, γ = 97.89(3)°, V= 3.964(2)nm3, Z = 2. Each manganese atom is hexacoordinated in both compounds and compound 2 is organized inchains by hydrogen bonds between neighboring pairs of NITPhCl and IMHPhCl.     

Synthesis,crystal structure and pseudocapacitor electrode properties of γ-Bi2MoO6 nanoplates

Nanoplate-like bismuth molybdates (γ-Bi₂MoO₆) is prepared for the first time by urea assisted solution combustion synthesis (SCS) and studied the structural and electrochemical properties to explore the possibility of using as negative electrodes in pseudocapacitors. The formation of single phase γ-Bi₂MoO₆ and plate-like morphology is revealed from XRD Rietveld refinement and FESEM, respectively. The pseudocapacitive behaviour of γ-Bi₂MoO₆ is analyzed by cyclic voltammetry and galvanostatic charge–discharge techniques. The effect of Na based aqueous electrolytes on capacitance of the Aurvillius type structured Bi₂MoO₆ is investigated. As prepared γ-Bi₂MoO₆ nanoplates provide the high specific capacitance (519 F g⁻¹) compared with the high-temperature monoclinic phase γ(H) Bi₂MoO₆ in 1 M NaOH electrolyte. The obtained high specific capacitance of as prepared Bi₂MoO₆ could be attributed to the decrease in particle size, increase in active sites, and nanoplate-like structure of as prepared γ-Bi₂MoO₆.     

Synthesis of a C60 complex withN,N,N′,N′-tetramethyl-p-phenylenediamine and its crystal structure

The complex of fullerene C₆₀ withN,N,N,N-tetramethyl-p-phenylenediamine (TMPD) was synthesized and studied by X-ray analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1285–1287, May, 1996. 1996     

Synthesis,crystal structure and physical properties of Yb11Bi10 − xSnx

The intermetallic phase Yb₁₁Bi_{10 − x}Sn_x (x = 0 and 4.8) crystallizing in the Ho₁₁Ge₁₀ structure type was synthesized and characterized. The crystal structure was established by single-crystal X-ray diffraction data in the tetragonal space group I4/mmm (no.139), Pearson code tI84, Z = 4, a = 12.2043(4) Å, c = 17.7227(9) Å, and V = 2639.7(2) Å³, R_gt(F) = 0.040, 763 observed reflections for Yb₁₁Bi₁₀, and a = 12.0183(5) Å, c = 17.413(1) Å, and V = 2515.1(2) Å³, R_gt(F) = 0.027, 762 observed reflections for Yb₁₁Bi_5.2Sn_4.8. The crystal structure of Yb₁₁Bi₁₀ contains three discrete anionic moieties: isolated Bi³⁻ anions, Bi₂⁴⁻ dimers and Bi₄⁴⁻ squares. In Yb₁₁Bi_5.2Sn_4.8, the square units are formed solely by Sn, and the structure shows a mixed Bi/Sn occupancy at the 8i and 16m Wyckoff sites. Magnetization measurements show that the title phase contains ytterbium exclusively in the 4f¹⁴ configuration up to 400 K. The Yb-L_III X-ray absorption spectrum attests also the presence of Yb with a 4f¹⁴ (Yb²⁺) configuration for Yb₁₁Bi₁₀, while the average valence of ytterbium was found to be 2.09 for Yb₁₁Bi_5.2Sn_4.8.