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Abstract  

The effect of -radiation on the electronic absorption spectra of the negatively solvatochromic dyestuff1, namely, 4-(4-N,N,-dimethylaminostyryl)-pyridinium methiodide in water and dimethylsulphoxide solvents is investigated. Ionizing radiation at different absorbed doses brought about gradual bleaching of aerated dye solutions. The -radiation-induced degradation and the consequent changes in the electronic absorption spectrum of dye 1 are discussed in the light of the theoretically calculated spectrum. The linear response range of dye1 in case of DMSO solution is wider than that in H2O. The results demonstrate that the radiochromic dye solution offer dosimetry in the low dose range by means of visible spectrophotometric analysis.

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Transition metal complexes with thiosemicarbazide-based ligands

31. Dioxouranium(VI) complexes with N(1),N(4)-bis(salicyIidene)- and N(1)-benzoylisopropylidene-N(4)-saIicylidene-S-alkyl-isothio-semicarbazides

Journal of Thermal Analysis and Calorimetry
Authors: V. Leovac, E. Ivegeš, K. Szécsényi, K. Tomor, G. Pokol, and S. Gal

Abstract  

Solvate complexes of UO2 2+ andN(1), N(4)-bis(salicylidene)-S-methylisothiosemicarbazone, (H2Me-L1), of general formula [UO2(Me-L1)S] (S= H2O, MeOH, EtOH, Py, DMF and DMSO) were synthesized. The methanolic UO2 2+” adducts of N(1)-benzoylisopropylidene-N(4)-salicylidene-S-alkylisothiosemicarbazone, (H2R-L2,R=Me, Prn) of general formula [UO2(R-L2)· MeOH], were also prepared. Thermal decomposition of the complexes was investigated in air and argon. The complexes decompose to α-U3O8 in air, while in argon the decomposition is not completed up to 1000 K. The temperature and the mechanism of decomposition of the complexes are a function of the solvent belonging to the inner coordination sphere.

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Abstract  

The paper describes the synthesis of low molecular mass poly(allyl chloride) (PAC) (M n= 856-3834 g mol-1) using Lewis acid (ALCL3, FeCL3, TiCL4) and al powder. Branching in PAC was indicated on the basis of elemental analysis and 1H-NMR spectroscopy. azidation of pac could be carried out at 100°C by using NaN3 and DMSO as solvent. Curing of poly(allyl azide) (PAA) by cyclic dipolar addition reaction with EGDMA (ethylene glycol dimethacrylate, 5-45 phr) was investigated by differential scanning calorimetry and structure of cured polymer was confirmed by FTIR. A two-step mass loss was exhibited by uncured and cured PAA in nitrogen atmosphere. A mass loss of 20-28% (155-274°C) and 50-61% (330-550°C) was observed.

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Transition-metal complexes with hydrazides and hydrazones

7. Dioxomolybdenum(VI) complexes of salicylaldehydep-hydroxybenzoylhydrazone and their thermal stability

Journal of Thermal Analysis and Calorimetry
Authors: I. Ivanović, K. Andjelković, V. M. Leovac, Lj. Klisarov, M. Lazarević, and D. Minić

Several new complexes of dioxomolybdenum(VI) of the general formula [MoO2(L)S], whereL is the dianion of salicylaldehydep-hydroxybenzoylhydrazone andS denotes H2O, MeOH, py, PPh3, DMSO or DMF, were synthesized and characterized by elemental analysis, electronic UV-VIS and IR spectra, thermal analysis, molar conductivity and magnetic susceptibility measurements. Salicylaldehydep-hydroxybenzoylhydrazone participates in the coordination as a tridentate ligand with the ONO set of donor atoms. The complexes contain acis-MoO2 group and are of octahedral geometry. Complexes of the MoO2L type were also prepared by synthesis in CHCl3 solution and by isothermal heating of [MoO2(L)S] complexes. The MoO2L complex synthesized in CHCl3 solution has most probably a pentacoordinated structure while the complex obtained by isothermal heating of [MoO2(L)S] has a polymeric hexacoordinated structure.

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Abstract  

The new mixed ligand complexes with formulae M(4-bpy)(C2H5COO)22H2O (where M(II)=Mn, Co, Ni; 4,4'-bpy or 4-bpy=4,4'-bipyridine) and Cu(4-bpy)0.5(C2H5COO)2H2O were prepared and characterized by VIS (for solid compounds of Co(II), Ni(II), Cu(II) in Nujol), IR spectroscopy, X-ray powder diffraction and molar conductance in MeOH, DMF or DMSO. Thermal behaviour of complexes was studied under static conditions in air atmosphere. Corresponding metal oxides were identified as final products of pyrolysis. A coupled TG-MS system was used to analysis of principal volatile thermal decomposition and fragmentation products of isolated complexes under dynamic air and argon atmosphere. The principal species correspond to: C+, OH+, H2O+, NO+, CO2 + and other; additionally CO+ in argon atmosphere.

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Rod-shaped nanocrystals are formed by self assembly of t -Bu-phenyl substituted tetra(carboxamido)perylenes (BPP) in different solvents. The structure and the dimensions of the nano-rods may be controlled by the choice of the hydrogen-bond accepting capacity of the solvent (DMSO, DMF, DMAc, HMPA), by the concentration and by the composition of solvent-mixture (by adding hydrogen-bond donating solvents), but is independent of the surface used for their deposition (mica, silicon, gold, glass). The different forms of aggregation were examined by AFM and SNOM and were correlated to UV-Vis absorption spectra of the aggregates in solution. The orientation of the transition dipole moment of the molecules in the nanocrystals has been determined by polarized fluorescence microscopy and, in combination with the crystal structure of the t -Bu substituted analogue of BPP, is used to develop a model for the internal molecular structure of the rod shaped aggregates.

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The chromatographic properties of eight steroids: trans-andros-terone, methyltestosterone, testosterone, progesterone, cortisone, hydrocortisone, estrone, and β-estradiol were studied by planar chromatography by use of aluminum oxide plates as well as of four different binary mobile phases (acetonitrile-water, acetonitrile-DMSO, acetone-petroleum ether, and acetone-water). Correlations between chromatographic data and physicochemical parameters were presented as results of established quantitative structure-retention relationships (QSRRs). Principal component analysis (PCA) and multiple linear regression (MLR) showed the possible relationships between the retentions and the physicochemical parameters of the studied compounds. The evaluation of thin-layer chromatographic (TLC) separation power, based on ΔhR F, was also discussed. Finally, two chromatographic systems for the effective separation of glucocorticoids and other analyzed steroid hormones were recommended.

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Abstract  

This article is dedicated to develop an experimental approach for directly visualizing the global freezing phase change behavior of micro liquid droplets. The infrared (IR) thermograph was proposed to image the basic solidification phenomena of droplet and to acquire its temperature variations during the transient process. In particular, the volumetric recalescence event, regarded as initiation of freezing, was revealed by IR images for the first time. Preliminary results demonstrated that the involved temperature transition due to release of the latent heat can be accurately characterized by evident color break in IR images. Further, experiments were also performed simultaneously on three kinds of droplets made of pure water, dimethylsulfoxide (DMSO) and nano liquid to grasp more precise temporal and spatial temperature distribution. Types of the occurring solidification and the initial frozen volume produced from the recalescence were generally discussed. The IR monitoring method suggests a straightforward way for detecting the freezing phase change activity and its temperature evolution at micro scale.

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Abstract  

Four new mixed ligand complexes were prepared by the reaction of title metal dichloroacetates and 2,4'-bipyridine. The general formulae of synthesized compounds are M(2,4'-bpy)2(CCl2HCOO)2 nH2O (where M(II)=Mn, Co, Ni, Cu; 2,4'-bpy=2,4'-bipyridine, n=2 or 4). The complexes have been isolated from aqueous media and characterized by chemical analysis, molar conductance (in MeOH, DMSO and DMF), magnetic, IR and VIS spectral studies. The nature of metal(II)-ligand coordination is discussed. The thermal behaviour of obtained complexes was studied by thermal analysis and TG-MS techniques in air. IR, X-ray powder diffraction and thermoanalytical data were used for the determination of solid intermediate products of the thermal decomposition. The principal volatile products of thermal decomposition of complexes were proved by mass spectroscopy: H2O+, CO+ 2, HCl+ 2, Cl+ 2, NO+ and other.

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The synthetic scope of photo-induced copper-mediated polymerization (photoCMP) in continuous-flow reactors is further explored. A series of monomers, namely, methyl (MA), ethyl (EA), n-butyl (nBA), 2-hydroxyethyl (HEA), and di(ethylene glycol) ethyl ether (DEGA) acrylate are investigated, all showing high livingness (dispersity in the range of 1.1 and linear first order kinetics) in the polymerizations and high conversions within 20-min reaction time. Next to the commonly used solvent (dimethyl sulfoxide [DMSO]), also a water—ethanol mixture was used as greener alternative, without any loss in reaction control. Upscaling the reactor from 2 to 16 mL allows for production of over 200 g of high-definition material (3000 g/mol, 1.1 dispersity) in overnight operation (18 h), demonstrating that the photoprocess can be run under very stable conditions even for extended reaction times. Via coupling of two reactors, direct chain extension of copolymers in a single reaction step is also demonstrated.

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