Synthesis and crystal structure of Nb2S4(S2NCEt2)4, the first molecular complex containing an [Nb2(μ2-S2)2]4+ fragment

The crystal structure was determined for Nb₂S₄(S₂NCEt₂)₄ obtained in 48% yield by the reaction of Cs₄Nb₂S₄(NCS)₈ with NaS₂CNEt₂ in water: a=21.181(8), b=6.958(1), c=16.623(6) Å, =133.95(2)^o, V = 1764(1) ų, space group C2/m, Z=2, d_calc=1.708 g/cm³. The measurements were carried out on a Syntex P2₁ diffractometer with CuK radiation. A total of 2536 reflections were measured, of which 990 were used, R_aniso=0.0444. The basic fragment in this molecule is [Nb₂(₂–S₂)₂]⁴⁺, the Nb–Nb distance in which corresponds to a metal-metal single bond. The molecule is partially disordered over two positions about the twofold axis and mirror plane of the C2/m space group. The dithiocarbamate and disulfide ligands with bidentate coordination form a distorted square antiprism about each of the niobium atoms as in NbS₂Cl₂. The anomalously large S–S bond length in the S₂ ligand [2.282(5) Å] may be attributed to inaccuracy in the determination due to disorder.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 134–138, March–April, 1993.     

ESR spectra of products of oxidation of endometallofullerenes M@C82 (M = Y,La, Ce,Gd)

The ESR spectra of the products of oxidation of solutions and powders of Y@C₈₂ and La@C₈₂ with fuming sulfuric acid were studied. Based on the oxidation conditions and the sequence of spectral patterns, the spectra were attributed to the radical cations M@C₈₂ ⁿ⁺ (n = 2, 4), dimers M³⁺ ₂@C₁₆₄ ⁺, and polyendometallofullerenes.     

Inclusion of Two PhP(O)(OH) 2 Guest Molecules into the Cavity of Macrocyclic Cavidand Cucurbit[8]uril

A new inclusion compound which is a supramolecular adduct of cucurbit[8]uril with two guest molecules of phenylphosphonic acid, PhP(O)(OH)₂, included into the cavity as ``two guests in host'' is reported. The guests match both size and hydrophilicity/hydrophobicity requirements. Two phenyl groups of molecules of PhP(O)(OH)₂ are directed toward the center of the large hydrophobic cavity whereas the PO(OH)₂ groups are outward-looking and bound with each hydrophilic portal of cucurbit[8]uril by a short hydrogen bond.     

Inclusion of nickel(<Emphasis Type="SmallCaps">II</Emphasis>) and copper(<Emphasis Type="SmallCaps">II</Emphasis>) complexes with aliphatic polyamines in cucurbit[8]uril

The inclusion compound of macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex containing the tetraazamacrocyclic ligand cyclam, {[Ni(cyclam)]@CB[8]}Cl₂··16H₂O (1), and the inclusion compounds of CB[8] with the copper(II) bis-ethylene-diamine complex, {trans-[Cu(en)₂(H₂O)₂]@CB[8]}Cl₂·{CB[8]}·42H₂O (2a) and {trans-[Cu(en)₂(H₂O)₂]@CB[8]}Cl₂·17H₂O (2b), were synthesized and characterized by X-ray diffraction analysis, IR and ESR spectroscopy, and electrospray mass spectrometry. Guest—host inclusion compounds can be directly synthesized starting from a metal complex and cucurbit[8]uril, as was exemplified by the preparation of compounds 2a and 2b.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2414–2419, November, 2004.     

Zn2+-dependent peptide nucleic acids probes

Binding of bis-picolylamine-naphthalene diimide-peptide nucleic acid conjugates to complementary DNA is strongly dependent upon Zn2+; ultimately, hybridization is switched ON in the presence muM Zn2+.     

Investigation of the mechanism of reaction of S-ethyl-N,N′-tetraethyldiamidothio-phosphite with [C5H 5Mn(CO)2NO]+BF by fourier transform infrared spectroscopy

FT-IR spectroscopy and a special mathematical program were used for the real-time monitoring of the mechanistic path of the reaction of S-ethyl-N,N-tetraethyldiamidothiophosphite with [CpMn(CO)-₂NO]⁺BFequation/tex2gif-stack-3.gif. The formation of a few intermediates is described.     

Synthesis of the <Emphasis Type="Italic">O</Emphasis>-(2-chloropyridin-5-ylmethyl)oxime of 20-hydroxyecdysone

The new ecdysteroid derivative 20-hydroxyecdysone O-(2-chloropyridin-5-ylmethyl)oxime (3) was synthesized via the reaction of 20-hydroxyecdysone (1) and O-(2-chloropyridin-5-ylmethyl)hydroxylamine (2) in Py in the presence of SnCl₄.     

Magnetic nanocarriers of doxorubicin coated with poly(ethylene glycol) and folic acid: relation between coating structure, surface properties, colloidal stability, and cancer cell targeting

We report the efficient one-step synthesis and detailed physicochemical evaluation of novel biocompatible nanosystems useful for cancer therapeutics and diagnostics (theranostics). These systems are the superparamagnetic iron oxide nanoparticles (SPIONs) carrying the anticancer drug doxorubicin and coated with the covalently bonded biocompatible polymer poly(ethylene glycol) (PEG), native and modified with the biological cancer targeting ligand folic acid (PEG-FA). These multifunctional nanoparticles (SPION-DOX-PEG-FA) are designed to rationally combine multilevel mechanisms of cancer cell targeting (magnetic and biological), bimodal cancer cell imaging (by means of MRI and fluorescence), and bimodal cancer treatment (by targeted drug delivery and by hyperthermia effect). Nevertheless, for these concepts to work together, the choice of ingredients and particle structure are critically important. Therefore, in the present work, a detailed physicochemical characterization of the organic coating of the hybrid nanoparticles is performed by several surface-specific instrumental methods, including surface-enhanced Raman scattering (SERS) spectroscopy, X-ray photoelectron spectrometry (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). We demonstrate that the anticancer drug doxorubicin is attached to the iron oxide surface and buried under the polymer layers, while folic acid is located on the extreme surface of the organic coating. Interestingly, the moderate presence of folic acid on the particle surface does not increase the particle surface potential, while it is sufficient to increase the particle uptake by MCF-7 cancer cells. All of these original results contribute to the better understanding of the structure-activity relationship for hybrid biocompatible nanosystems and are encouraging for the applications in cancer theranostics.