Micromorphology Characterization of SiO2-Based Composite Thin Films with Immobilized Terbium(III) Complex

The aim of this study was to investigate by atomic force microscopy and multifractal analysis the three-dimensional (3-D) of surface micromorphology of the complex of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methyl)]bis-(4-hydroxy-2H-1-benzopyran-2-one), Tb(C₂₅H₁₅O₇)₃ · 5H₂O immobilized in transparent SiO₂-based films by a simple casting technique. The 3-D surfaces contain irregularities of various orders spread on the surface due to the intrinsic method of surface preparation. We found that the micromorphology of all analyzed samples has multifractal characteristics. The generalized dimension D _q and the singularity spectrum f(α) provided quantitative values that describe the degree of heterogeneity in the 3-D surface geometry at nanometer scale. The results showed that the larger the spectrum width Δα (Δα = α _max  ? α _min ) of the multifractal spectra f(α), the more nonuniform is the surface micromorphology. These results demonstrate that multifractal analysis is a more precise and reliable tool for quantitative characterization of 3-D surface micromorphology.     

Effects of composition drift on the effectiveness of random copolymer reinforcement at polymer–polymer interfaces

Random copolymer layers are surprisingly effective at reinforcing polymer–polymer interfaces. One hypothesis is that composition drift during synthesis can account for the higher than expected toughening. To test this hypothesis, we polymerized a series of poly(d‐styrene‐r‐2‐vinylpyridine) (dPS_f‐r‐PVP_1?f) copolymers with various fractions (f) of deuterated styrene to only 10% completion to avoid composition drift. The fracture energies (G_c) of polystyrene/dPS‐r‐PVP/poly(2‐vinylpyridine) interfaces with relatively thick layers of dPS‐r‐PVP were measured. G_c decreased relative to interfaces reinforced with composition‐drifted dPS‐r‐PVP. Conversely, G_c increased when two or more copolymers were blended together. In such samples, the copolymers form distinct layers with multiple interfaces characterized by the difference in f (Δf) between adjacent layers. We find that G_c is governed by Δf_max, the largest difference in adjacent compositions, and, therefore, by the width of the narrowest interface (w_min). G_c increases strongly as w_min increases from 3 to 5 nm. Remarkably, these w_min values are about half the entanglement spacing in bulk polystyrene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2363–2377, 2001     

Dimeric copper(II) trimethylsilyl­acetate adducts with pyridine, 2‐­methylpyridine, 3‐methylpyridine and quinoline,and a polymeric copper(II) trimethylsilylacetate

In the crystals of bis(pyridine‐N)tetrakis(μ‐trimethylsilylacetato‐O:O′)dicopper(II), [Cu₂(C₅H₁₁O₂Si)₄(C₅H₅N)₂], (I), the dinuclear Cu^II complexes have cage structures with Cu?Cu distances of 2.632 (1) and 2.635 (1) Å. In the crystals of bis(2‐­methylpyridine‐N)tetrakis(μ‐trimethylsilylacetato‐O:O′)dicopper(II), [Cu₂(C₅H₁₁O₂Si)₄(C₆H₇N)₂], (II), bis­(3‐methylpyridine‐N)tetrakis(μ‐trimethylsilylacetato‐O:O′)dicopper(II), [Cu₂(C₅H₁₁O₂Si)₄(C₆H₇N)₂], (III), and bis(quinoline‐N)­tetrakis(μ‐­trimethylsilylacetato‐O:O′)dicopper(II), [Cu₂(C₅H₁₁O₂Si)₄(C₉H₇N)₂], (IV), the centrosymmetric dinuclear Cu^II complexes have a cage structure with Cu?Cu distances of 2.664 (1), 2.638 (3) and 2.665 (1) Å, respectively. In the crystals of catena‐poly­[tetrakis(μ‐trimethylsilylacetato‐O:O′)dicopper(II)], [Cu₂(C₅H₁₁O₂Si)₄]_n, (V), the dinuclear Cu^II units of a cage structure are linked by the cyclic Cu—O bonds at the apical positions to form a linear chain by use of a glide translation.     

Researches on Thermal Decomposition Kinetics of Composite Modified Double-base Propellants

The thermal decomposition kinetics of composite modified double‐base (CMDB) propellants with a series of contents of hexogeon (RDX) was investigated by using parameters of T_eo, T_i, T_p, T_f, T_b, T_a, E, lg A and ΔH, which were obtained from using a CDR‐4P differential scanning calorimeter (DSC) and Perkin‐Elmer Pyris 1 thermogravimetric analyzer (TG) analyses with heating rates of 5, 10, 15 and 20 K/min. Reliable activation energy was calculated using Flynn‐Wall‐Ozawa method before analyzing the thermal decomposition mechanism. TG‐DTG curves were treated with Malek method in order to obtain the reaction mechanisms. The obtained results show that the thermal decomposition mechanisms with the conversion from 0.2 to 0.4 was f(α)?1/2α, and with the conversion from 0.5 to 0.7 was f(α)?(1/4)(1?α)[?ln(1?α)]^?3.     

Ratios of average molecular weights and molecular weight distributions in polymers

If M_min and M_max are lower and upper bounds, respectively, to the molecular weights of different molecular weight species contained in a polymer, the weight-average to number-average molecular weight ratio M _w/M _n cannot exceed (1 + M_max/M_min)²/(4M_max/M_min). The ratio attains this maximum possible value if the masses of the two species with molecular weights M_min and M_max are equal and the masses of all the other species are negligibly small, corresponding to maximum spread in the molecular weight distribution within the specified bounds. Also for a given value of M _w/M _n = α, the M_max cannot be smaller than [2α ? 1 + 2α^1/2(α ? 1)^1/2]M_min. The minimum possible value of M_max/M_min consistent with α given is obtained in the case of maximum spread described above. If only one species is predominant, then both M _w/M _n and M_max/M_min approach unity, as is well known. Similar relations hold for the ratios of higher-order average molecular weights for which the role of the mass fractions is replaced by higher-order distribution functions.     

Synthesis,Bonding and Reactivity of a Terminal Titanium Alkylidene Hydrazido Compound

We report a detailed study of the reactions of the Ti?NNCPh₂ alkylidene hydrazide functional group in [Cp*Ti{MeC(NiPr)₂}(NNCPh₂)] ( 8 ) with a variety of unsaturated and saturated substrates. Compound 8 was prepared from [Cp*Ti{MeC(NiPr)₂}(NtBu)] and Ph₂CNNH₂. DFT calculations were used to determine the nature of the bonding for the Ti?NNCPh₂ moiety in 8 and in the previously reported [Cp₂Ti(NNCPh₂)(PMe₃)]. Reaction of 8 with CO₂ gave dimeric [(Cp*Ti{MeC(NiPr)₂}{μ‐OC(NNCPh₂)O})₂] and the “double‐insertion” dicarboxylate species [Cp*Ti‐{MeC(NiPr)₂}{OC(O)N(NCPh₂)C(O)O}] through an initial [2+2] cycloaddition product [Cp*Ti{MeC(NiPr)₂}{N(NCPh₂)C(O)O}], the congener of which could be isolated in the corresponding reaction with CS₂. The reaction with isocyanates or isothiocyanates tBuNCO or ArNCE (Ar=Tol or 2,6‐C₆H₃iPr₂; E=O, S) gave either complete NNCPh₂ transfer, [2+2] cycloaddition to Ti?N_α or single‐ or double‐substrate insertion into the Ti?N_α bond. The treatment of 8 with isonitriles RNC (R=tBu or Xyl) formed σ‐adducts [Cp*Ti{MeC(NiPr)₂}(NNCPh₂)(CNR)]. With Ar^F5CCH (Ar^F5=C₆F₅) the [2+2] cycloaddition product [Cp*Ti{MeC(NiPr)₂}{N(NCPh₂)C(Ar^F5)C(H)}] was formed, whereas with benzonitriles ArCN (Ar=Ph or Ar^F5) two equivalents of substrate were coupled in a head‐to‐tail manner across the Ti?N_α bond to form [Cp*Ti{MeC(NiPr)₂}{N(NCPh₂)C(Ar)NC(Ar)N}]. Treatment of 8 with RSiH₃ (R=aryl or Bu) or Ph₂SiH₂ gave [Cp*Ti{MeC(NiPr)₂}{N(SiHRR′)N(CHPh₂)}] (R′=H or Ph) through net 1,3‐addition of Si? H to the N? N?CPh₂ linkage of 8 , whereas reaction with PhSiH₂X (X=Cl, Br) led to the Ti?N_α 1,2‐addition products [Cp*Ti{MeC(NiPr)₂}(X){N(NCPh₂)SiH₂Ph}].     

Mixed micellization and surface properties of non-ionic/cationic surfactants

We investigate the surface properties of aqueous binary mixtures of our cationic surfactant O-dodecyl-N,N′-diisopropylisourea hydrochloride (ISO-DIC C₁₂) with commercially available nonionic surfactant polyoxyethylene p-(1,1,3,3-tetramethylbutyl)phenyl ether (TritonX-100) at different temperatures (288 to 303?K). The micellization behavior of the binary systems is studied by determining the surface tension and other important physicochemical parameters, such as the critical micelle concentration (CMC), surface tension at the CMC(γ_cmc), Krafft Temperature (T_K), maximum excess concentration (Γ_max), minimum surface area per molecule (A_min), surface pressure at the CMC (П_cmc), and the adsorption efficiency (pC20) at the air/water interface. The study has additionally covered the calculation of thermodynamic parameters of micellization, including the standard Gibbs free energy, the standard enthalpy, the standard entropy, the free energy, and the Gibbs free energy of adsorption at air/water interface. The CMC values of the binary systems determined by experimental data are used to evaluate the micellar composition in the mixed micelle, the interaction parameter β and the activity coefficients f₁(ISO-DIC C₁₂) and f₂ (polyoxyethylene p-(1,1,3,3-tetramethylbutyl)phenyl ether) using the theoretical treatment proposed by Clint and Rubingh. Our results reveal that the proposed binary systems possess enhanced surface activity compared to those of the individual surfactants.     

Darstellung,Kristallstruktur, Schwingungsspektren und Normalkoordinatenanalyse von (Ph4P)2[OsN(N3)5] und 15N‐NMR‐Verschiebungen von Nitridoosmaten(VI,VIII)

Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of (Ph₄P)₂[OsN(N₃)₅] and ¹⁵N NMR Chemical Shifts of Nitridoosmates(VI, VIII) The treatment of (Ph₄P)[OsNCl₄] with NaN₃ yields (Ph₄P)₂[OsN(N₃)₅], which crystal structure has been determined by single crystal X‐ray diffraction analysis (monoclinic, space group P 2₁/a, a = 20.484(6), b = 11.168(1), c = 20.666(4) Å, β = 97.35(3)°, Z = 4). The IR and Raman vibrations were assigned by a normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are f_d(Os≡N) = 8.52, f_d(Os–N^α) = 1.99, f_d(N^α–N^β) = 12.42, f_d(N^β–N^γ) = 12.73 and for the azido ligand in trans‐position to the nitrido group f_d(Os–N^{α ·} ) = 1.84, f_d(N^{α ·} –N^{β ·} ) = 11.91, f_d(N^{β ·} –N^{γ ·} ) = 12.18 mdyn/Å. The ¹⁵N NMR spectra of various nitridoosmates reveal the chemical shifts δ(¹⁵N) for K[OsO₃¹⁵N] = 387.6, K₂[Os¹⁵NCl₅] = 446.7, (Ph₄P)[Os¹⁵NCl₄] = 352.9, [(n‐C₆H₁₃)₄N]₂[Os¹⁵N(N₃)₅] = 307.3 and for [(n‐Pr)₄N]₂[Os¹⁵N(¹⁵NCO)₅] = 483,7 (Os≡N), –417,7 (OsNCO_eq) und –392,8 ppm (OsNCO_ax).     

Theoretical and experimental analyses of the deposited silver thin films

The silver thin films have been prepared using magnetron DC‐sputtering. We discuss in detail the thin films AFM images and their properties in different sputtering times of 2 to 6 minutes. Despite the low thickness of the films, the roughness saturation amounts, W_s, are well separated. The surface data do not follow the normal Family‐Vicsek scaling, and we have the local growth exponent, β(W_s(t)∼t^β). We obtained the global roughness scaling exponent α=0.36 and growth exponent, β=0.50. We also obtain the fractal spectrum of the data, f(α). The results show that the spectrum is right‐hook like. It distinguishes between different film thicknesses even in small sizes of hundreds of nanometers. Furthermore, we measure the surface conductivities and compare them to the thin film roughnesses. We investigate the roughness and fractality of the AFM data, looking for their relations to width and conductivity of the silver thin film samples.     

On the evaluation of the nonisothermal kinetic parameters of (GeS2)0.3(Sb2S3)0.7 crystallization using the IKP method

The isoconversional method suggested by Friedman and the invariant kinetic parameters method (IKP) were used in order to examine the kinetics of the nonisothermal crystallization of (GeS₂)_0.3(Sb₂S₃)_0.7. The objective of the paper is to show the usefulness of the IKP method both for determining the activation parameters as well as the model of the investigated process. It was shown that the kinetic triplet [(E, A, f(α), where E is the activation energy, A is the preexponential factor, and f(α) is the differential function of conversion], which results through the application of the IKP method, depends on the set of kinetic models considered. For different sets of kinetic models, proportional values of f(α) are obtained. A criterion for the selection of this set, the use of which lead to the true kinetic triplet corresponding to the analyzed process (E = 163.2 kJ mol^?1; A = 2.47 × 10¹² min^?1 and the Avrami‐Erofeev model, A_m, for m = 2.5–2.6 was suggested. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 309–315, 2004     

Multifractal analysis of drop‐casted copper (II) tetrasulfophthalocyanine film surfaces on the indium tin oxide substrates

This paper applies multifractal spectrum theory to characterize the structural complexity of 3D surface roughness of copper (II) tetrasulfophthalocyanine (CuTsPc) films on the indium tin oxide (ITO) substrate, obtained with atomic force microscopy (AFM) analysis. CuTsPc films were prepared by drop cast method on ITO substrate. CuTsPc films surface roughness was studied by AFM in tapping‐mode?, in air, on square areas of 2500 µm². A novel approach, on the basis of computational algorithms for analysis of 3D roughness surface applied for AFM data, was presented. Results revealed that the 3D surface roughness of CuTsPc films prepared by drop cast method on ITO substrate can be described using the multifractal geometry. The generalized dimensions D_q and the multifractal spectrum f(α) provided quantitative values that characterize the local scale properties of CuTsPc films surface geometry at nanometer scale. Data provide valuable information to describe the spatial arrangement of 3D surface roughness of CuTsPc films on ITO substrate, which was not taken into account by classical surface statistical parameters. Copyright © 2014 John Wiley & Sons, Ltd.     

Electronic structures of YBa2Cu3OY doped by La

Based on the EHMO approach, the band structures for the Y? Ba? Cu? O superconductors doped by La were calculated. The influence of the partial substitutions of La for Y and Ba in YBa₂CU₃O_y on its electronic structures was investigated. The results demonstrate that the La doping at the Ba site has a great effect on the electronic structures of the Y? Ba? Cu? O superconductors, whereas the change in the band structures caused by the La doping at the Y site is very small. The increase in the oxygen content caused by the La doping results in an increase in the densities of states at E_f, N(E_f), for La_1+x Ba_2?xCu₃O_y, but the increase in N(E_f) cannot compensate the decrease caused by the La doping at the Ba site. In addition, the 2D Cu? O planes are much more sensitive to the change in N(E_f) than are the 1D Cu? O ribbons, which implies an important role of the 2D Cu? 0 planes in the Y? Ba? Cu? O superconducting system, regardless of whether La substitutes for Y or for Ba. © 1995 John Wiley & Sons, Inc.     

Reactivity of substituted copper(II) salicylates with tert‐butylperoxyl radical: Structure–reactivity relationships

Absolute rate constants (k_eff) for the chemical reactions of Cu(II)₂(3,5‐di‐iso‐propylsalicylate)₄(H₂O)₃, Cu(II)₂(3,5‐di‐tert‐butylsalicylate)₄, Cu(II)₂(3,5‐di‐tert‐butylsalicylate)₄(H₂O)₄, Cu(II)₂(3,5‐dimethylsalicylate)₄(H₂O)₃, Cu(II)₂(3‐ethylsalicylate)₄(H₂O), Cu(II)₂(3‐phenylsalicylate)₄, and Cu(II)(3,5‐di‐iso‐propylsalicylate)₂(pyridine)₂ with tert‐butylperoxyl radical were determined using kinetic electron paramagnetic resonance measurements in 10% toluene in the hexane medium at temperatures ranging from ?63°C to 2°C. These antioxidant (AO) chelates were ranked by their reactivity as follows: 2,6‐di‐tert‐butyl‐4‐methylphenol ? Cu(II)₂(3,5‐di‐tert‐butylsalicylate)₄ ? Cu(II)₂(3‐phenylsalicylate)₄ > Cu(II)₂(3,5‐di‐iso‐propylsalicylate)₄(H₂O)₃ ? Cu(II)₂(3,5‐di‐tert‐butylsalicylate)₄(H₂O)₄ ? Cu(II)₂(3,5‐dimethylsalicylate)₄(H₂O)₃ > Cu(II)₂(3‐ethylsalicylate)₄(H₂O) ? Cu(II)(3,5‐di‐iso‐propylsalicylate)₂(pyridine)₂ at 20°C. Differential pulse voltammetry was used to determine redox behavior of these chelates in CH₂Cl₂. Two types of salicylic OH groups were detected in these Cu(II) salicylates, characterized by the presence or absence of AO reactivity. One of them was coordinate covalently bonded to Cu(II) via the oxygen atoms of the salicylic OH groups, displaying oxidation peak potentials in the range from +650 to 970 mV versus Ag/Ag⁺. The second type was intramolecularly hydrogen bonded to carboxylate oxygens, with an oxidation peak potential in the range from +1100 to 1200 mV versus Ag/Ag⁺. It was concluded that non–hydrogen‐bonded salicylic OH groups are responsible for the antiperoxyl radical reactivity of these chelates, while neither Cu(II) nor salicylate ligands displayed reactivity with peroxyl radical. It has been established in this research that axially bonded electron pair donors such as pyridine and water decrease H‐donating reactivity of Cu(II) salicylates by promoting the formation of intramolecular hydrogen bonding between the salicylic OH hydrogen atoms and carboxylate oxygen atoms in the salicylic ligands. Dependences of log k_eff at 20°C and the anodic oxidation potential (E_pa) for the salicylic OH group on the difference between symmetric and asymmetric stretching frequencies of carboxylate groups (in Fourier transform infrared spectra) for the substituted Cu(II) salicylates were determined. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 56–67, 2010     

From Disilene (SiSi) to Phosphasilene (SiP) and Phosphacumulene (PCN)

The generation of heavier double‐bond systems without by‐ or side‐product formation is of considerable importance for their application in synthesis. Peripheral functional groups in such alkene homologues are promising in this regard owing to their inherent mobility. Depending on the steric demand of the N‐alkyl substituent R, the reaction of disilenide Ar₂Si?Si(Ar)Li (Ar=2,4,6‐iPr₃C₆H₂) with ClP(NR₂)₂ either affords the phosphinodisilene Ar₂Si?Si(Ar)P(NR₂)₂ (for R=iPr) or P‐amino functionalized phosphasilenes Ar₂(R₂N)Si? Si(Ar)?P(NR₂) (for R=Et, Me) by 1,3‐migration of one of the amino groups. In case of R=Me, upon addition of one equivalent of tert‐butylisonitrile a second amino group shift occurs to yield the 1‐aza‐3‐phosphaallene Ar₂(R₂N)Si? Si(NR₂)(Ar)? P?C?NtBu with pronounced ylidic character. All new compounds were fully characterized by multinuclear NMR spectroscopy as well as single‐crystal X‐ray diffraction and DFT calculations in selected cases.     

Darstellung,Kristallstrukturen und Schwingungsspektren von trans‐[Pt(N3)4(ECN)2]2–, E = S,Se

Synthesis, Crystal Structures, and Vibrational Spectra of trans ‐[Pt(N₃)₄(ECN)₂]^2–, E = S, Se By oxidative addition to (n‐Bu₄N)₂[Pt(N₃)₄] with dirhodane in dichloromethane trans‐(n‐Bu₄N)₂[Pt(N₃)₄(SCN)₂] and by ligand exchange of trans(n‐Bu₄N)₂[Pt(N₃)₄I₂] with Pb(SeCN)₂ trans‐(n‐Bu₄N)₂[Pt(N₃)₄(SeCN)₂] are formed. X‐ray structure determinations on single crystals of trans‐(Ph₄P)₂[Pt(N₃)₄(SCN)₂] (triclinic, space group P 1, a = 10.309(3), b = 11.228(2), c = 11.967(2) Å, α = 87.267(13), β = 75.809(16), γ = 65.312(17)°, Z = 1) and trans‐(Ph₄P)₂[Pt(N₃)₄(SeCN)₂] (triclinic, space group P 1, a = 9.1620(10), b = 10.8520(10), c = 12.455(2) Å, α = 90.817(10), β = 102.172(10), γ = 92.994(9)°, Z = 1) reveal, that the compounds crystallize isotypically with octahedral centrosymmetric complex anions. The bond lengths are Pt–S = 2.337, Pt–Se = 2.490 and Pt–N = 2.083 (S), 2.053 Å (Se). The approximate linear Azidoligands with N^α–N^β–N^γ‐angles = 172,1–175,0° are bonded with Pt–N^α–N^β‐angles = 116,7–120,5°. In the vibrational spectra the platinum chalcogen stretching vibrations of trans‐(n‐Bu₄N)₂[Pt(N₃)₄(ECN)₂] are observed at 296 (E = S) and in the range of 186–203 cm^–1 (Se). The platinum azide stretching modes of the complex salts are in the range of 402–425 cm^–1. Based on the molecular parameters of the X‐ray determinations the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are f_d(PtS) = 1.64, f_d(PtSe) = 1.36, f_d(PtN^α) = 2.33 (S), 2.40 (Se) and f_d(N^αN^β, N^βN^γ) = 12.43 (S), 12.40 mdyn/Å (Se).     

Crystallographic report: Fluoro‐bis‐iso‐propyl‐(2,4,6‐tris‐iso‐propylphenyl)‐ silane,i‐Pr2(2,4,6‐i‐Pr3C6H2)SiF

Owing to steric congestion in i‐Pr₂(2,4,6‐i‐Pr₃C₆H₂)SiF, the geometry at the Si atom deviates slightly from ideal tetrahedral geometry with an increased C? Si? C angle of 119.02(9)° and elongated Si? C and Si? F bond distances. Copyright © 2005 John Wiley & Sons, Ltd.     

Chemical solution processing and characterization of Ba(Zr,Ti)O<Subscript>3</Subscript>/LaNiO<Subscript>3</Subscript> layered thin films

Ba(Zr,Ti)O₃/LaNiO₃ layered thin films have been synthesized by chemical solution deposition (CSD) using metal-organic precursor solutions. Ba(Zr,Ti)O₃ thin films with smooth surface morphology and excellent dielectric properties were prepared on Pt/TiO _x /SiO₂/Si substrates by controlling the Zr/Ti ratios in Ba(Zr,Ti)O₃. Chemically derived LaNiO₃ thin films crystallized into the perovskite single phase and their conductivity was sufficiently high as a thin-film electrode. Ba(Zr,Ti)O₃/LaNiO₃ layered thin films of single phase perovskite were fabricated on SiO₂/Si and fused silica substrates. The dielectric constant of a Ba(Zr_0.2Ti_0.8)O₃ thin film prepared at 700°C on a LaNiO₃/fused silica substrate was found to be approximately 830 with a dielectric loss of 5% at 1 kHz and room temperature. Although the Ba(Zr_0.2Ti_0.8)O₃ thin film on the LaNiO₃/fused silica substrate showed a smaller dielectric constant than the Ba(Zr_0.2Ti_0.8)O₃ thin film on Pt/TiO _x /SiO₂/Si, small temperature dependence of dielectric constant was achieved over a wide temperature range. Furthermore, the fabrication of the Ba(Zr,Ti)O₃/LaNiO₃ films in alternate thin layers similar to a multilayer capacitor structure was performed by the same solution deposition process.     

Imino‐Bridged Bisphosphaalkenes (2,4‐Diphospha‐3‐azapentadienes)

Deprotonation of aminophosphaalkenes (RMe₂Si)₂C?PN(H)(R′) (R=Me, iPr; R′=tBu, 1‐adamantyl (1‐Ada), 2,4,6‐tBu₃C₆H₂ (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe₂Si)₂C?P(M)(R′)] with one equivalent of the corresponding P‐chlorophosphaalkenes (RMe₂Si)₂C?PCl provides bisphosphaalkenes (2,4‐diphospha‐3‐azapentadienes) [(RMe₂Si)₂C?P]₂NR′. The thermally unstable tert‐butyliminobisphosphaalkene [(Me₃Si)₂C?P]₂NtBu ( 4 a ) undergoes isomerisation reactions by Me₃Si‐group migration that lead to mixtures of four‐membered heterocyles, but in the presence of an excess amount of (Me₃Si)₂C?PCl, 4 a furnishes an azatriphosphabicyclohexene C₃(SiMe₃)₅P₃NtBu ( 5 ) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P?C double bond and an exocyclic ylidic P⁽⁺⁾? C^(?)(SiMe₃)₂ unit. Using the bulkier iPrMe₂Si substituents at three‐coordinated carbon leads to slightly enhanced thermal stability of 2,4‐diphospha‐3‐azapentadienes [(iPrMe₂Si)₂C?P]₂NR′ (R′=tBu: 4 b ; R′=1‐Ada: 8 ). According to a low‐temperature crystal‐structure determination, 8 adopts a non‐planar structure with two distinctly differently oriented P?C sites, but ³¹P NMR spectra in solution exhibit singlet signals. ³¹P NMR spectra also reveal that bulky Mes* groups (Mes*=2,4,6‐tBu₃C₆H₂) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P? N bonds in persistent compounds [(RMe₂Si)₂C?P]₂NMes* ( 11 a , 11 b ). DFT calculations for the parent molecule [(H₃Si)₂C?P]₂NCH₃ suggest that the non‐planar distortion of compound 8 will have steric grounds.     

Autopoisoning reactions over rough surface: A multifractal scaling analysis

The effect of surface roughness and number of reaction event on the decay type diffusion limited reaction (DLR) over rough surface of random deposition model was studied to examine the surface morphological effect on the surface reaction. Effect of decay profiles on the reaction probability distribution (RPD) of the reaction was then analyzed with multifractal scaling techniques. The dynamics of these autopoisoning reactions is controlled by the two parameters, namely, the initial sticking probability ( P _ini) of every site and the decay rate (m). More the rough surface, less are the number of active sites and wider is the distribution of reaction probability. More the number of reaction events, more are the number of active sites and more is the homogeneity in the RPD. The q‐τ(q) multifractal curves are found to be nonlinear for all the cases which give wide range of α values in α‐f(α) multifractal spectrum. Smaller the decay rate, narrower is the range of α values. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 175–182, 2005     

环丙沙星-钨硅多金属氧酸盐的制备及热分解动力学

A new polyoxometalate （CPFX·HCl）3H4SiW12O40·10H2O was prepared from ciprofloxacin hydrochloride and H4SiW12O40·nH2O in aqueous solution, and characterized by elemental analysis, IR spectra and DTA-TG-DTG techniques. The IR spectrum confirmed the presence of Keggin structure and the characteristic functional group for ciprofloxacin in the compound. The TG-DTA-DTG curves showed that its thermal decomposition was a four-step process consisting of simultaneous collapse of Keggin type structure. The residue of decomposition was the mixture of WO3 and SiO2, confirmed by X-ray diffraction and IR spectroscopy. The decomposition mechanism and nonisothermal kinetic parameters of the polyoxometalate were obtained from an analysis to the TG-DTG curves by the single scanning methods （the Achar method and Coats-Redfern method） and the multiple scanning methods （the Kissinger method, Flynn-Wall-Ozawa method and Starink method）. The results indicate that the kinetic equationswith parameters describing the thermal decomposition reaction are dα/dt=6.65×10^6[3（1-α）^2/3]e^-10495.5/T with E=87.26 kJ/mol and A=6.65×10^6 s^-1 for the second step,dα/dt=7.01×10^9（1-α）e^-18770.7/T with E=156.06 kJ/mol and A=7.01×10^9 s^-1 for the third step,dα/dt=9.77×10^43[（1-α）^2]e^-88980.0/T with E=739.78 kJ/mol and A=9.77×10^43 s^-1 for the fourth step.