共查询到20条相似文献,搜索用时 31 毫秒
1.
The photoproduct of octacyanomolybdate(IV) and -tungstate(IV) with ethylenediamine and triethylenetetramine give complexes of the type K3[Mo(O2)(O)(OH)(C9H7ON)]·3C9H7ON I, K2[W(O2)(O) (C9H7ON)3] II and K3[Mo(CN)3(OH)4(C9H7ON)]·2C9H7ON·3H2O III with 8-quinolinol (oxine). The IR spectra of the complex III shows the presence ofv(CN) peaks in the range 2047–2108 cm?1 and oxine groupv(C-O) in the complex I, II and III in the range of 1100–1150 cm?1. The lower region of IR spectra shows the M=O stretching while the higher thev(N-H) andv(OH). Thermal studies show the removal of uncoordinated water at 131?C from complex III. The decomposition of complexes I and II start from 150 and 212?C respectively. Oxine and cyano molecules were removed in stages at higher temperatures. The final product of the thermal decomposition was oxide which was of polymeric nature. The kinetic parameters viz. order of reaction ‘n’ and activation energy ‘E’ were determined by different methods. 相似文献
2.
Durant AT MacKenzie KJ Maekawa H 《Dalton transactions (Cambridge, England : 2003)》2011,40(18):4865-4870
A combined sol-gel and solid-state method reported for the synthesis of gallium silicate analogues of aluminosilicate inorganic polymers has also been extended to the formation of related compounds with a range of Al-for Ga substitutions. Homogeneous, robust products were obtained at an optimum composition of SiO(2):(Ga(2)O(3) + Al(2)O(3)) = 7. After curing at 40 °C, all the products were typically X-ray amorphous, and the Al and Ga was shown by (27)Al and (71)Ga MAS NMR spectroscopy to be in solely tetrahedral coordination. The (29)Si MAS NMR spectra were as expected for silicate inorganic polymers, but also indicated the presence of some unreacted silica. Electron microscopy in conjunction with EDS elemental mapping showed that the Ga, Al and Si was homogeneously distributed in the products. Thermal treatment of these compounds results in endothermic water loss at about 75-160 °C followed by an exothermic event at about 950 °C corresponding to crystallization of KGaSi(2)O(6) in the gallium end-member. By contrast, the Al-substituted compounds never fully crystallised, but melted at 1200 °C to an X-ray amorphous product. 相似文献
3.
C. V. Yelamaggad Manoj Mathews Uma Hiremath Geetha Nair D. S. Shankar Rao S. Krishna Prasad 《Liquid crystals》2003,30(8):899-908
A series of symmetrical dimers consisting of salicylaldimine moieties connected by flexible alkylene central spacer via ether linkages has been synthesized. In order to validate the empirical rule suggested by Date et al. to account for the smectic behaviour of such dimers, the chain length of the terminal alkoxy chain has been kept constant (C8) while the number of methylene units in the central spacer was varied from C3 to C11. Another aim of the present investigation was to understand structure-property relationship in these dimers in which the salicylaldimine mesogenic segment has been used for the first time in dimers. The mesomorphic behaviour of these dimers was evaluated using optical microscopy and differential scanning calorimetry and the structure of some of the mesophases has been further investigated with the help of X-ray diffraction. Our studies reveal that the dimers consisting of 3 to 8 methylene units in the flexible spacer show only smectic (smectic C and smectic A) phases. For the dimers containing 4, 6 and 8 methylene units in the central spacer, a unique filament growth pattern has been observed in the smectic A phase while cooling from the isotropic phase. The dimers containing of C9 to C11 methylene groups exhibit the nematic phase in addition to smectic modifications. This observation indicates that when the terminal chains are shorter than the spacer, the tendency to form smectic phases is not fully extinguished but is perhaps reduced. 相似文献
4.
C. V. Yelamaggad Manoj Mathews Uma Hiremath Geetha Nair D. S. Shankar Rao S. Krishna Prasad 《Liquid crystals》2013,40(8):899-908
A series of symmetrical dimers consisting of salicylaldimine moieties connected by flexible alkylene central spacer via ether linkages has been synthesized. In order to validate the empirical rule suggested by Date et al. to account for the smectic behaviour of such dimers, the chain length of the terminal alkoxy chain has been kept constant (C8) while the number of methylene units in the central spacer was varied from C3 to C11. Another aim of the present investigation was to understand structure-property relationship in these dimers in which the salicylaldimine mesogenic segment has been used for the first time in dimers. The mesomorphic behaviour of these dimers was evaluated using optical microscopy and differential scanning calorimetry and the structure of some of the mesophases has been further investigated with the help of X-ray diffraction. Our studies reveal that the dimers consisting of 3 to 8 methylene units in the flexible spacer show only smectic (smectic C and smectic A) phases. For the dimers containing 4, 6 and 8 methylene units in the central spacer, a unique filament growth pattern has been observed in the smectic A phase while cooling from the isotropic phase. The dimers containing of C9 to C11 methylene groups exhibit the nematic phase in addition to smectic modifications. This observation indicates that when the terminal chains are shorter than the spacer, the tendency to form smectic phases is not fully extinguished but is perhaps reduced. 相似文献
5.
Luminita Marin Vasile Cozan Maria Bruma Vasile Cristian Grigoras 《European Polymer Journal》2006,42(5):1173-1182
A new poly(azomethine-ether) was synthesized by the reaction of bisphenol A with a thermotropic azomethine monomer, namely 4,4′-oxy-bis(4-chlorobenzylideneimino phenylene). In order to understand the influence of the molecular weight on the thermal properties, four fractions were isolated from the initial polymer. They were investigated by elemental analysis and spectroscopic methods (IR, UV, 1H NMR) and their thermal behaviour was studied by differential scanning calorimetry, optical microscopy, thermogravimetrical analysis. An increase of the thermal transition temperatures and mesophase order with increasing molecular weight was noticed. 相似文献
6.
J. M. Salas-Peregrin J. Suarez-Varela 《Journal of Thermal Analysis and Calorimetry》1984,29(3):515-521
Some indigodisulphonates of Cr(III), Cu(II), Ag(I), An(II) and Cd(II) have been prepared in aqueous medium and characterized on the basis of elemental analyses, diffuse reflectance infrared spectra and magnetic measurements.The thermal behaviours of these salts were studied by TG, DTG and DSC techniques. Cr(III), Cu(II), Zn(II) amd Cd(II) indigodisulphonates contain 12, 2, 2 and 2 molecules of crystallization water, respectively. The end-products of thermal decomposition have been verified by infrared spectroscopy and X-ray diffraction. Values of dehydration enthalpies have been calculated from the DSC curves.
Zusammenfassung Einige Indigodisulphonate von Cr(III), Zn(II), Ag(I), Zn(II) und Cd(II) wurden in wäßrigem Medium dargestellt und durch Elementaranalyse, diffuse Reflektions-IR-Spektren und magnetische Messungen charakterisiert. Das thermische Verhalten dieser Salze wurde mittels TG, DTG und DSC untersucht. Die Indigodisulphonate von Cu(II), Zn(II) und Cd(II) kristallisieren mit 2 Molekülen Kristallwasser, die von Cr(III) mit 12 Molekülen. Die Endprodukte der thermischen Zersetzung wurden infrarotspektroskopisch und röntgendiffraktometrisch identifiziert. Die Werte der Dehydratisierungsenthalpien wurden aus den DSC-Kurven berechnet.
, , . , . , . , , , , 12, 2, 2 2 ) . - . - .相似文献
7.
Four titanium silanolates Ti(OSiR2R′)4 (1, R = Ph, R′ = tBu; 2, R = R′ = Ph; 3, R = R′ = iPr; 4, R = Me, R′ = tBu) were synthesised starting from Ti(OiPr)4 and the corresponding silanol, and their thermally induced decomposition was studied. Colourless single crystals of Ti(OSiPh Bu) CHCl C7H8 ( CHCl C7H8) were obtained from a mixture of chloroform and toluene (1:1) at ?20 °C. The compound crystallizes in the space group R3 c with Z = 18. The metal atom shows an almost ideal tetrahedral coordination, as is demonstrated by the O? Ti? O angles of 108.4(1)–111.1(1)°. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
8.
Edward Krzyżak Berenika Szczęśniak-Sięga Wiesław Malinka 《Journal of Thermal Analysis and Calorimetry》2014,115(1):793-802
A series of potential biologically active 2-[3-(4-phenyl-1-piperazinyl)propyl]-3-(4-substituted-benzoyl)-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides was synthesized in a straightforward manner by condensation of respective 3-substituted-4-hydroxy-1,2-benzothiazine 1,1-dioxides with 1-(1-chloropropyl)-4-phenylpiperazine. The structures of all of the newly formed compounds were identified by elemental analysis, FTIR and 1H NMR. The synthesized compounds were subjected to preliminary evaluation using differential scanning calorimetry (DSC) to determine the existence of multiple crystal forms. The DSC scans for all compounds show more than one endothermic effect, which might suggest dynamic proton transfer between two or three possible tautomeric forms: O-keto/O-enol, O-enol/O-keto and O-keto/O-keto/CH2 in crystals 2-[3-(4-phenyl-1-piperazinyl)propyl]-3-(4-substituted-benzoyl)-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides. 相似文献
9.
10.
P. R. Dametto B. Ambrozini A. B. Siqueira C. T. Carvalho M. Ionashiro 《Journal of Thermal Analysis and Calorimetry》2010,101(3):933-939
Solid-state Ln(L)3 compounds, where Ln stands for trivalent Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, and L is 3-methoxybenzoate, have been synthesized.
X-ray powder diffractometry, infrared spectroscopy, complexometry and elemental analysis were used to characterize the compounds.
In order to study the thermal behaviour of these compounds simultaneous thermogravimetry and differential thermal analysis
(TG-DTA) and differential scanning calorimetry (DSC) were used. The results provided information on the composition, dehydration,
polymorphic transformation, thermal stability and thermal decomposition of the synthesized compounds. 相似文献
11.
E. Tomaszewicz J. Typek S. M. Kaczmarek 《Journal of Thermal Analysis and Calorimetry》2009,98(2):409-421
Three series of new copper and rare-earth metal tungstates with the formulas: CuRE 2W2O10 (RE = Nd, Sm, Eu) and Cu3 RE 2W4O18 (RE = Sm, Eu or RE = Dy, Ho, Er) were synthesized by the solid-state reaction method. The CuRE 2W2O10 and Cu3 RE 2W4O18 (RE = Dy, Ho, Er) compounds crystallize in the monoclinic system. The Cu3 RE 2W4O18 phases with the large rare-earth ions crystallize in the triclinic system. All obtained compounds melt incongruently below 1273 K. The anion lattice of the Cu3 RE 2W4O18 phases is built from isolated groups of octahedra (W4O16)8?, while CuRE 2W2O10 from WO6 octahedra forming structural elements [(W2O9)6?]∞. The EPR spectra of analyzed compounds consisted of an intense line originating generally from the rare-earth ions and a weak, narrow line from Cu2+ separate centers appearing only on the surface of the grains. The absence of bulk copper in the EPR spectrum is probably due to a very short relaxation time of the Cu2+ subsystem. 相似文献
12.
C. V. Yelamaggad S. Anitha Nagamani Uma S. Hiremath D. S. Shankar Rao S. Krishna Prasad 《Liquid crystals》2002,29(11):1401-1408
Several symmetrical dimers comprised of salicylaldimine-moieties connected through ester linkages to the termini of odd-parity alkanediols have been synthesized and investigated for their thermal behaviour. In order to understand the structure-property relations, the lengths of the central alkylene spacers (C3 and C5) as well as those of the terminal alkoxy chains (C6 to C22) have been varied. The dimers with a C3-alkylene spacer are non-liquid crystalline, while some of the compounds having a C5-alkylene spacer exhibit liquid crystalline properties. The dimer, with a C5-alkylene spacer and C6-alkoxy tails, shows an intercalated smectic C (SmCc) phase, whereas the C8, C10, C11, and C12 homologues are non-mesomorphic. The higher homologues of this series with C16, C18, C20 and C22 alkoxy tails show a mesophase that has the signatures of a two-dimensional banana (B1) phase. This mesophase is enantiotropic in the C16 and C18 homologues while it is monotropic in the other homologues. In these dimers, the spacer length has a remarkable influence on the thermal behaviour. 相似文献
13.
C. V. Yelamaggad S. Anitha Nagamani Uma S. Hiremath D. S. Shankar Rao S. Krishna Prasad 《Liquid crystals》2013,40(11):1401-1408
Several symmetrical dimers comprised of salicylaldimine-moieties connected through ester linkages to the termini of odd-parity alkanediols have been synthesized and investigated for their thermal behaviour. In order to understand the structure-property relations, the lengths of the central alkylene spacers (C3 and C5) as well as those of the terminal alkoxy chains (C6 to C22) have been varied. The dimers with a C3-alkylene spacer are non-liquid crystalline, while some of the compounds having a C5-alkylene spacer exhibit liquid crystalline properties. The dimer, with a C5-alkylene spacer and C6-alkoxy tails, shows an intercalated smectic C (SmCc) phase, whereas the C8, C10, C11, and C12 homologues are non-mesomorphic. The higher homologues of this series with C16, C18, C20 and C22 alkoxy tails show a mesophase that has the signatures of a two-dimensional banana (B1) phase. This mesophase is enantiotropic in the C16 and C18 homologues while it is monotropic in the other homologues. In these dimers, the spacer length has a remarkable influence on the thermal behaviour. 相似文献
14.
Synthesis and thermal behaviour of liquid crystalline pyridinium bromides containing a biphenyl core
A range of new pyridinium bromides was synthesized by the quaternization of different substituted pyridines with a group containing a biphenyl core and alkyl chains of differing lengths. The phase behaviour of the pyridinium bromides was studied by differential scanning calorimetry, polarizing optical microscopy and powder X-ray diffraction. It is shown that pyridinium moieties, linked to a rod-like biphenyl core via an alkyl spacer, can form ionic liquid crystals. Unsubstituted pyridinium groups promote mesomorphism. Liquid crystalline phases are formed only from 2- and 4-ethyl substituted pyridinium groups with sufficiently long alkyl terminal chains and spacers; i.e. decyl chains on both sides of the biphenyl core. Both the substitution pattern at the pyridinium group and the alkyl chain length have an influence on the polymorphism of the smectic phases. 3,5-Dimethyl substitution hinders mesophase formation. 相似文献
15.
A. B. Siqueira C. T. Carvalho E. Y. Ionashiro G. Bannach E. C. Rodrigues M. Ionashiro 《Journal of Thermal Analysis and Calorimetry》2008,92(3):945-951
Solid-state Ln(L)3 compounds, where Ln stands for trivalent Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y and L is 2-methoxybenzoate have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential
scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and complexometry were used to characterize
and to study the thermal behaviour of these compounds. The results provided information on the composition, dehydration, coordination
mode, structure, thermal behaviour and thermal decomposition. 相似文献
16.
Synthesis and thermal behaviour of liquid crystalline pyridinium bromides containing a biphenyl core
A range of new pyridinium bromides was synthesized by the quaternization of different substituted pyridines with a group containing a biphenyl core and alkyl chains of differing lengths. The phase behaviour of the pyridinium bromides was studied by differential scanning calorimetry, polarizing optical microscopy and powder X-ray diffraction. It is shown that pyridinium moieties, linked to a rod-like biphenyl core via an alkyl spacer, can form ionic liquid crystals. Unsubstituted pyridinium groups promote mesomorphism. Liquid crystalline phases are formed only from 2- and 4-ethyl substituted pyridinium groups with sufficiently long alkyl terminal chains and spacers; i.e. decyl chains on both sides of the biphenyl core. Both the substitution pattern at the pyridinium group and the alkyl chain length have an influence on the polymorphism of the smectic phases. 3,5-Dimethyl substitution hinders mesophase formation. 相似文献
17.
A series of silicon containing poly(ester imide)s [PEIs] were synthesized using novel vinyl silane diester anhydride (VSEA)
and various aromatic and aliphatic dimines by two-step process includes ring-opening polyaddition reaction to form poly(amic
acid) and thermal cyclo-dehydration process to obtain poly(ester imide)s. VSEA was synthesized by using dichloro methylvinylsilane
and trimellitic anhydride in the presence of K2CO3 by nucleophilic substitution reaction. The PEIs were characterized by FTIR spectroscopy. The thermal properties of PEIs were
investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The prepared PEIs
showed glass transition temperatures in the range of 320–350°C and their 5% mass loss was recorded in the temperature range
of 500–520°C in nitrogen atmosphere. These had char yield in the range of 45–55% at 800°C. 相似文献
18.
Synthesis and thermal behaviour of polyamide 6/bentonite/ammonium polyphosphate composites 总被引:1,自引:0,他引:1
J.B. Dahiya M. Muller-Hagedorn B.K. Kandola 《Polymer Degradation and Stability》2008,93(11):2038-2041
In order to achieve acceptable levels of flame retardancy of polymers, phosphorus-based flame retardant (FR) additives at about 20-30% w/w are required which is too high for conventional synthetic fibres. To know whether more finely sized particles of conventional FRs with or without nanoclay are more effective at the same concentration, composites of PA6 with bentonite and ammonium polyphosphate (APP) have been prepared by melt processing in a twin-screw extruder. XRD peaks and TEM images of PA6/Org-bentonite composite show partially ordered intercalation and ordered exfoliation. Thermal analysis in He shows that thermal stability of PA6 nanocomposite has increased by 18 °C compared with pure PA6 during degradation after 425 °C but it has decreased by 100 °C on inclusion of APP in PA6/nanoclay composites. The char yield is increased by 20% in PA6/bentonite/APP composites. No effect on thermal stability or char yield is observed by reducing the particle size of APP. 相似文献
19.
《Polyhedron》1987,6(9):1757-1763
[MmFe(CN)5L·xH2O] (M = Mn, Fe, Co, Ni, Cu; L = pyridine or pyrazine derivative) have been synthesized, and their UV-vis and IR spectral characteristics are reported. Thermolysis of the solids leads to water release, ligand release and/or decomposition, redox interaction between Fe3+ (or Cu2+) with CN− or L, and redox interaction between M2+ (or Cu+) and CN−, yielding elemental metal and metal carbides. 相似文献
20.
J. R. Locatelli E. C. Rodrigues A. B. Siqueira E. Y. Ionashiro G. Bannach M. Ionashiro 《Journal of Thermal Analysis and Calorimetry》2007,90(3):737-746
Solid-state Ln(Bz)3·H2O compounds where Ln stands for trivalent yttrium or lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetry-differential
thermal analysis (TG-DTA), X-ray powder diffractometry, infrared spectroscopy and chemical analysis were used to characterize
and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration,
thermal stability and thermal decomposition of the isolated compounds. 相似文献