A vanadium(IV) phosphite with a pillared layered structure: hydrothermal synthesis and characterization of (VO)4(4,4'-bpy)2(HPO3)4

A novel vanadium(IV) phosphite, (VO)(4)(4,4'-bpy)(2)(HPO(3))(4), was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the monoclinic system with the space group C2/c and cell parameters a = 35.970(3) A, b = 15.9400(13) A, c = 10.7681(7) A, beta = 101.073(4) degrees, and Z = 8 with R(1) = 0.0482. The structure of the compound consists of trigonal bipyramidal [VO(4)N] and pseudopyramidal [HPO(3)] blocks, which are connected by corner-sharing, to form vanadium phosphite layers in the bc plane. These layers are further linked through 4,4'-bpy pillars, generating a 3D framework. Thermogravimetric analysis and magnetic susceptibility data for this compound are given.     

Interaction of Fluorocarbon Containing Hydrophobically Mdified Polyelectrolyte with Nonionic Surfactants

The interaction of fluorocarbon containing hydrophobically modified polyelectrolyte(FMPAANa) with two kinds of nonionic surfactants(hydrogenated and fluorinated)in a semidilute (0.5wt%) aqueous solution had been studied by rheological measurements,Association behavior was found in both systems.The hydrophobic interaction of FMPAANa with fluorinated surfactant(FC171) is much stronger than that with hydrogenated surfactant(NP7.5) at low surfactoant concentrations.The interaction is strengthened by surfactants being added for the density of active junctions increased.Whereas distinct phenomena for FC171 and NP7.5 start to be found as the surfactants added over their respective certain concentration.The interaction of polyelectrolyte with fluorinated surfactant increases dramatical ly while that with hydrogenated surfactant decreases.     

A theoretical study of the interactions between N, N-dimethylformamide and aromatic hydrocarbons

The B3LYP and MP2 methods with 6-31G* basis set were used to predict the geometries of N, N-dimethylformamide (DMF) dimer and DMF–aromatic hydrocarbons interaction systems. A total of 10 conformers were obtained with no imaginary frequencies, respectively. The interaction energies of these binary mixtures have been obtained. The analyses of chelpg charge distribution and the atoms in molecules theory (AIM) were used to analyze the nature of the interaction. The results show the presence of hydrogen bonds between DMF and aromatic hydrocarbons. The interaction between DMF and benzonitrile is the strongest with the interaction energy of −21.58 kJ mol⁻¹ (BSSE corrected), and the intensity order of interactions is DMF–benzonitrile: d2 > DMF–DMF: a2 > DMF–toluene: c1 > DMF–benzene: b2.     

Surmounting tumor resistance to metallodrugs by co-loading a metal complex and siRNA in nanoparticles

Copper complexes are promising anticancer agents widely studied to overcome tumor resistance to metal-based anticancer drugs. Nevertheless, copper complexes per se encounter drug resistance from time to time. Adenosine-5′-triphosphate (ATP)-responsive nanoparticles containing a copper complex CTND and B-cell lymphoma 2 (Bcl-2) small interfering RNA (siRNA) were constructed to cope with the resistance of cancer cells to the complex. CTND and siRNA can be released from the nanoparticles in cancer cells upon reacting with intracellular ATP. The resistance of B16F10 melanoma cells to CTND was terminated by silencing the cellular Bcl-2 gene via RNA interference, and the therapeutic efficacy was significantly enhanced. The nanoparticles triggered a cellular autophagy that amplified the apoptotic signals, thus revealing a novel mechanism for antagonizing the resistance of copper complexes. In view of the extensive association of Bcl-2 protein with cancer resistance to chemotherapeutics, this strategy may be universally applicable for overcoming the ubiquitous drug resistance to metallodrugs.

Bcl-2-related tumor resistance to anticancer drugs can be overcome by silencing the cellular Bcl-2 gene via RNA interference. The realization of the goal is exemplified by delivering Bcl-2 siRNA and a tumor-resistant Cu complex to cancer cells with an ATP-responsive nanocarrier.     

Structures and stability of N7+ and N7− clusters

Ab initio molecular orbital theory and density functional theory have been used to study nine isomers of N₇ ionic clusters with low spin at the HF/6-31G*, MP2/6-31G*, B3LYP/6-31G*, and B3LYP/6-311(+)G* levels of theory. All stationary points are examined with harmonic vibrational frequency analyses. Four N₇ ⁺ isomers and five N₇ ⁻ isomers are determined to be local minima or very close to the minima on their potential-energy hypersurfaces, respectively. For N₇ ⁺ and N₇ ⁻, the energetically low lying isomers are open-chain structures (C _{2 v} and C _{2 v} or C₂). The results are very similar to those of other known odd-number nitrogen ions, such as N₅ ⁺, N₉ ⁺, and N₉ ⁻, for which the open-chain structures are also the global minima. This research suggests that the N₇ ionic clusters are likely to be stable and to be potential high-energy-density materials if they could be synthesized. Received: 16 July 2001 / Accepted: 8 October 2001 / Published online: 21 January 2002     

An anomalous reaction of 10-chloro-5H-benzoxazolo[3,2-a]quinolin-5-one with sodium diethyl malonate to form 9-chloro-8-ethoxy-12-hydroxy-5H-dibenz[c,f]quinolizin-5-one

Treatment of 10-chloro-5H-benzoxazole[3,2-a]quinolin-5-one (I) with an excess of sodium diethyl malonate at 190° for 3 hours in hexamethylphosphoramide gave, in 38% yield, 9-chloro-8-ethoxy-12-hydroxy-5H-dibenz[c,f]quinolizin-5-one (IV) which, on heating with acetic anhydride, afforded monoacetylated product, V. A possible reaction mechanism for the novel ring expansion reaction is suggested.     

Dispersion state of CuO on CeO2

XRD and XPS are used to study the dispersion state of CuO on ceria surface. The dispersion capacity values of CuO measured by the two methods are consistent, which are of 1.20 mmol CuO/100 m² CeO₂. In addition, the results reveal that highly dispersed Cu²⁺ ions are formed at low CuO loadings and that increasing the CuO content to a value higher than its dispersion capacity produces crystalline CuO after the surface vacant sites on CeO₂ are filled. The atomic composition of the outermost layer of the CuO/CeO₂ samples has been probed by using static secondary ion mass spectroscopy (SSIMS), and the ratim of Cu/Ce are found to be 0.93 and 0.46 for the 1.22 and 0.61 mmol CuO/CeO₂ samples respectively. Temperature-programmed reduction (TPR) profile with two reduction peaks at 156 and 165°C suggests that the reduction of highly dispersed Cu²⁺ ions consists of two steps and is easier than that of CuO crystallites, in which the TPR profile has only one reduction peak at about 249°C. The above experimental results are in good agreement with the prediction of the incorporation model. Project supported by the National Natural Science Foundation of China.     

Orientational ordering of a bent-core mesogen by two-dimensional 13C NMR spectroscopy

Various two-dimensional (2D) NMR techniques are reported on a bent-core mesogen 4,6-dichloro-1,3-phenylenebis[4'-(9-decenyloxy)-1,1'-biphenyl] carboxylate in its nematic and solid phases in order to unambiguously assign its carbon-13 NMR spectrum. The (13)C chemical shifts from the molecular core were studied as a function of temperature to extract its molecular geometry and orientational order tensor. To this end, the chemical shift anisotropy tensors of some carbon sites were measured in the solid state of this mesogen using a recent method called the separation of undistorted powder patterns by effortless recoupling (SUPER). The average bending angle subtended by the two arms of the bent-core structure is determined to be 148.7 degrees. The C-H dipolar couplings obtained from the separated local field (SLF) experiment for the aromatic rings are used to find the local order parameter tensors.     

Two-photon excitation studies of hypocrellins for photodynamic therapy

The photophysical and photochemical properties of hypocrellins (HA and HB) are examined with two-photon excitations at 800 nm using femtosecond pulses from a Ti:sapphire laser. The two-photon excited fluorescence spectra of HA and HB are very similar to those obtained by one-photon excitation, which may indicate that the two-photon induced photodynamic processes of hypocrellins are similar to one-photon induced photodynamic processes. The two-photon excitation cross sections of HA and HB are measured at 800 nm as about 34.8 x 10(-50) cm(4) s/photon and 21.3 x 10(-50) cm(4) s/photon, respectively. The large two-photon cross sections of both HA and HB, suggest that the hypocrellins can be potential two-photon phototherapeutic agents. As an example for two-photon photodynamic therapy of hypocrellins, we also further examine the cell-damaging effects of HA upon two-photon illumination. Our preliminary results of cell viability test indicate hypocrellins can effectively damage the Hela cells under two-photon illumination.