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1.
Spectrophotometric titration is used to study the basic properties of a series of porphyrins with a continuously increasing degree of macrocycle deformation resulting from the introduction of strong electron-withdrawing substituents: 2,3,7,8,12,13,17,18-octaethylporphyrin (I), 5-nitro-2,3,7,8,12,13,17,18-octaethylporphyrin (II), 5,15-dinitro-2,3,7,8,12,13,17,18-octaethylporphyrin (III), 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin (IV), and 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin (V). It is found that the values of logK b (total basicity constants) obtained for the investigated compounds consistently diminish with an increase in the number of meso-substituents: 11.85 (I) > 10.45 (II) > 10.31 (III) > 10.23 (IV) > 9.56 (V). It is shown that two opposing factors, the steric and electronic effects of the substituents, change the basic properties of the above series of compounds.  相似文献   

2.
The gelation behaviors of four recently reported amphiphilic cholesteryl derivatives (1, 2, 3 and 4) have been evaluated. It was found that the gel formation process can be controlled by introduction of water at room temperature. Addition of water to an acetone solution of 4 immediately results in the system becoming turbid, and a gel subsequently forms within a few minutes. Interestingly, 4 is a super-gelator for a mixed solvent of acetone and water at room temperature, in particular when their volume ratio is close to 1:1 at which the critical gelation concentration (CGC) is 0.06% (w/v). It was found that the introduction of water favors the formation of gel networks, and the gel possesses smart and reversible thixotropic properties. FTIR and 1H NMR spectroscopy confirmed that hydrogen bonding is one of the main driving forces for the gelation of the solvents. XRD demonstrated that 4 self-assembled into a layered structure within the acetone-water mixed solvent gel. Furthermore, 1 and 2 can be used as excellent stabilizers for gel emulsions of alkanes and water. The maximum of the dispersed phase, water, in one of the gel-emulsions can be as high as 97% (v/v).  相似文献   

3.
The Schiff base bis(4-ethylbenzyl) p-phenylenediimine, 4-eb-p-phen (1), and six new dimeric Pd(II) complexes of the type [Pd(μ-X)(4-eb-p-phen)]2 {X = Cl (2), Br (3), I (4), N3 (5), NCO (6), SCN (7)} have been synthesized and characterized by elemental analysis, IR spectroscopy, and 1H and 13C{1H}-NMR experiments. The thermal behavior of the complexes 27 has been investigated by means of thermogravimetry and differential thermal analysis. From the final decomposition temperatures, the thermal stability of the complexes can be ordered in the following sequence: 3 > 4 > 7 > 2 ≈ 5 > 6. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction (XRD).  相似文献   

4.
The binuclear copper(II) complex [Cu2L(CH3COO)] (I), where L3? is the azomethine trianion based on 3-methyl-4-formyl-1-phenylpyrazol-5-one and 1,3-diaminopropan-2-ol, and its DMSO adduct (II) in which the DMSO molecule acts as an additional bridging ligand are synthesized. The structure of complex II is determined by X-ray diffraction analysis, and the structure parameters of the coordination unit of complex I are determined by EXAFS spectroscopy. The μ2-coordination of the DMSO molecule in compound II results in a change in the sign of the exchange interaction parameter. In complex I, the antiferromagnetic exchange interaction (2J = ?169 cm?1) occurs between the copper(II) ions. The exchange interaction of the ferromagnetic type (2J = 174 cm?1) is observed in complex II. The quantum-chemical calculations of the magnetic exchange parameters by the density functional theory method show that the role of the DMSO molecule as a switch of the exchange interaction character is exclusively the stabilization of the “broken” conformation of the metallocycles.  相似文献   

5.
Fourteen bis(citrato)germanates(IV) and bis(citrato)stannates(IV) were prepared, in particular, [M(H2O)6][Ge(HCit)2] · 4H2O (M = Mg (I), Mn (II), Fe (III), Co (IV), Ni (V), Cu (VI), Zn (VII)) and [M(H2O)6][Sn(HCit)2] · nH2O (M = Mg, n = 4 (VIII); Mn, n = 2 (IX); Fe, n = 4 (X); Co, n = 4 (XI); Ni, n = 4 (XII); Cu, n = 4 (XIII); Zn, n = 3 (XIV)) (H4Cit is citric acid). The purity and the composition of the products were determined by a set of physicochemical methods including elemental analysis, thermogravimetry, and IR spectroscopy. The structures of I, II, IV, VI, VII, VIII, XI, and XII were determined by X-ray diffractometry. All eight crystals composed of centrosymmetrical octahederal [M(H2O)6]2+ cations, [Ge(HCit)2]2? (or [Sn(HCit)2]2?) anions, and crystal water molecules are isostructural. The structural units in I, II, IV, VI, VII, VIII, XI, and XII are connected by systems of hydrogen bonds to form a three-dimensional framework.  相似文献   

6.
Three complexes with the formula [Co(Ip)(CuL)(H2O)2] · H2O (I), [Co(Ip)(NiL)(H2O)2] · H2O (II), [Co(CuL)2(Hbtc)(H2O)] (III), (H2Ip = m-isophthalic acid; H2L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien; H3Btc = 1,3,5-benzenetricarboxylic acid) were synthesized and structurally characterized by elemental analysis, IR and UV spectroscopy. Single-crystal X-ray analyses reveal that the complexes I and II contain neutral heterometallic binuclear CoM (for I and II, M = Cu, Ni, respectively) moieties, and complex III contains discrete neutral trinuclear CoCu2 moieties. The structures of IIII consist of two-dimensional supramolecular architecture formed by strong O-H…O intermolecular hydrogen bonds. Furthermore, the magnetic properties of complex I were investigated and discussed in detail.  相似文献   

7.
Two series of poly(imide-ester)s (PIEs) and poly(ether-imide-ester)s (PEIEs), having benzoxazole or benzothiazole pendent groups, were conveniently prepared by the diphenylchlorophosphate-activated direct polyesterification of two bis(imide-carboxylic acid)s (1), such as 2-[3,5-bis(N-trimellitimidoyl)phenyl]benzoxazole (1 O ) and 2-[3,5-bis(Ntrimellitimidoyl) phenyl]benzothiazole (1 S ) and two bis(imide-ether-carboxylic acid)s (2), such as 2-[3,5-bis(4-trimellitimidophenoxy)-phenyl]benzoxazole (2 O ), and 2-[3,5-bis(4-trimellitimidophenoxy)-phenyl]benzothiazole (2 S ) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. The structures, solubilities and thermal properties of obtained polymers were investigated in detail. All of the resulting polymers were characterized by FTIR and 1H-NMR spectroscopy and elemental analysis. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, tetrahydrofuran and m-cresol, as well as in polar organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide. The modified polymers were obtained in quantitative yields with inherent viscosities between 0.47 and 0.67 dl·g?1. Experimental results indicated that all the polymers had glass transition temperature between 198 °C and 262 °C, the decomposition temperature at 10% weight loss between 398 °C and 531 °C under nitrogen.  相似文献   

8.
Reaction of [VO(OPr i )3] (1) with [O(CH2CH2OH)2] in 1:1 molar ratio in anhydrous benzene yield glycol-modified precursor, [VO{OCH2CH2OCH2CH2O}{OPr i }] (2). Further reactions of (2) with internally functionalized oximes in anhydrous benzene yield heteroleptic complexes of the type [VO{OCH2CH2OCH2CH2O}{ON=C(R)(Ar)}] (3–8) {where R=CH3, Ar=C4H3O-2 (3), C4H3S-2 (4), C5H4N-2 (5); and when R=H, Ar=C4H3O-2 (6), C4H3S-2 (7), C5H4N-2 (8)}. All these derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic techniques. The crysoscopic molecular weight measurement as well as FAB mass study suggests dimeric nature of (2). However, FAB mass spectrum of (4), and the crysoscopic molecular weight measurements of (3), (4), (5) and (6) indicate the monomeric behavior of the oximato derivatives (3–8). Hexa-coordination around vanadium(V) has been proposed for both monomeric and dimeric derivatives. Sol–gel transformations of (1), (2) or (4) to vanadia [(a), (b) or (c), respectively] have been carried out at low sintering temperature (600 °C). The XRD patterns of (a), (b) or (c) indicate formation of a single orthorhombic phase in all the three cases. The SEM images suggest grain like [for (a) and (b)] and rod like [for (c)] morphology of the crystallites. IR, Raman spectra as well as EDX analyses indicate formation of pure vanadia. Absorption spectra of the vanadia (b) and (c) suggest energy band gaps of 2.53 and 2.65 eV, respectively.  相似文献   

9.
Three new coordination polymers, [Mn(BDC-F4)(DMF)2(H2O)2] n (1), [Ni(BDC-F4)(DMF)(EtOH)] n (2), and [Cd(BDC-F4)(DMF)(EtOH)] n (3), have been synthesized by assembling transition metal salts with the rigid ligand tetrafluoroterephthalic acid (H2BDC-F4) in mixed EtOH/DMF solvent at pH ca. 2. For complex 1, the octahedral coordination geometry of the MnII center is provided by two oxygen atoms from two dianionic BDC-F4 ligands, two DMF ligands and two aqua ligands, giving a 1-D linear chain array. For complex 2, the NiII center is coordinated by two dianionic BDC-F4 ligands, two EtOH ligands and two DMF ligands, resulting in a 1-D chain structure. For complex 3, the CdII center is coordinated by four dianionic BDC-F4 ligands, one EtOH ligand and one DMF ligand, generating a 2-D layered structure. The results suggest that both the metal and the solution pH play an important role in the formation of the complexes. The spectroscopic, thermal, and luminescence properties of the complexes have been investigated.  相似文献   

10.
The copper aminotropones Cu[ON(R′)C7H4R-4]2 [R = H, R′ = Me (13), Et (14), n-Pr (15), n-Bu (16), Bz (17), MenOCH2CH2 (20); R = i-Pr, R′ = Me (18), n-Pr (19), MenOCH2CH2 (21)] have been prepared from the corresponding aminotropones HN(R′)OC7H4R-4 (17) by reacting with copper(II) acetate in aqueous ethanol. 20, 21 contain the flavourant, menthol, as part of the ligand. The structures of 5 (R = H, R′ = Bz), a hydrogen-bonded dimer, 14 and 20, both incorporating square-planar, four-coordinate copper centres, have been determined by X-ray crystallography. The antibacterial activities of complexes 13, 17, 20 and 21 have been assayed against Staphylococcus waneri, an in vitro model of plaque inhibition effects, and found to be more active than a commercial toothpaste formulation, but less active than the O,O-chelated copper(II) complex of ethylmaltol.  相似文献   

11.
Five new complexes of general formula [PdX2(p-diben)], where p-diben = N,N′-bis(4-dimethylaminobenzylidene)ethane-1,2-diamine) (1) and X = Cl (2), Br (3), I (4), N3 (5), or CNO (6), were synthesized and characterized by physicochemical and spectroscopic methods. The crystal structure of compound (5) was determined by single-crystal X-ray diffraction. Complexes 26 were characterized as N,N-chelated products. The crystal structure confirmed this formulation for [Pd(N3)2(p-diben)], besides showing the isomerism inversion of one of the C=N bonds, caused by Pd(II) coordination.  相似文献   

12.
C3-Symmetry tris-urea low molecular weight gelator (LMWG) (1), which shows chemical stimuli responsible for a sol-gel phase transition, was divided into five regions. Based on the division, 22 derivatives were synthesized. The gelation ability of these derivatives was tested in nine organic solvents with a wide range of values for relative static permittivity (?r=47.2-1.89). Some derivatives showed a better performance as LMWGs than the original tris-urea LMWG (1). For example, the critical gelation concentration (CGC) in acetone was improved from 1.5 wt % to 0.5 wt % by changing the core substituent (18). Highly versatile LMWG for a variety of solvents was obtained by changing the linker moiety (23). Structural information to design tris-urea LMWGs is important to create rationally a functional supramolecular gel.  相似文献   

13.
Modification of [VO(OPri)3] with oximes in different molar ratios, yielded new class of vanadia precursors, [VO{OPri}3?n{L}n] {where, n = 1–3 and LH = C9H16C=NOH (1–3) and (CH3)2C=NOH (46)}.All the products are yellow in colour. (1) and (2) are liquid/viscous liquid, while others are solids. Molecular weight measurements of all these derivatives and the ESI-mass spectral studies of (1), (2), (3) and (5) indicate their monomeric nature. 1H and 13C{1H} NMR spectra suggest that the oximato moieties are monodentate in solution which was further confirmed by the 51V NMR signals, appeared in the region expected for tetra-coordinated oxo-vanadium atoms. On ageing, a disproportionation reaction occurs in (1) and some crystals appeared. Single crystal X-ray diffraction analyses of the crystals obtained from (1) as well as from (3) were found to be the same and indicate the presence of side-on {dihapto η 2-(N, O)} binding modes of the oximato ligands, leading to the formation of seven coordination environment around the vanadium atom. Thermogravimetric curve of (1) exhibits multi-step decomposition with the formation of V2O5 as the final product at ~850 °C. Sol–gel transformation of (3) yielded (a) VO2 sintered at 300 °C and (b) V2O5 at 600 °C. Similarly, sol–gel transformations of (1) and (2) yielded V2O5 (c) and (d) at 600 °C, respectively. Formation of monoclinic phase in (a) and orthorhombic phase in (b), (c) and (d) were confirmed by powder XRD patterns.  相似文献   

14.
Solvate Ph3Sb[OC(O)C6H4(OH-4)]2 · 1/2Et2O (I) has been synthesized by the reaction between triphenylantimony and 4-oxybenzoic acid in the presence of hydrogen peroxide in diethyl ether. Tetraphenylantimony 4-oxybenzoate, which crystallizes from DMSO in the form of solvate Ph4SbOC(O)C6H4(OH-4) · DMSO (II), has been synthesized from pentaphenylantimony and triphenylantimony bis(4-oxybenzoate) or 4-oxybenzoic acid. According to X-ray diffraction data, an antimony atom in molecules of compounds I and II has a trigonal bipyramidal coordination. Crystals of compound I contain two crystallographically independent types of molecules (A and B). The Sb-C and Sb-O distances, the equatorial CSbC and axial OSbO angles are, respectively, 2.083(9)–2.103(8)Å; 2.068(5), 2.128(5)Å; 117.6(3)°–124.2(3)° and 171.5(2)° (IA); 2.103(9)–2.135(8)Å; 2.086(5), 2.154(6)Å;110.2(3)°–138.0(4)° and 174.8(2)° (IB). In compound II, Sb-C is 2.117(2)–2.175(2) Å, Sb-O is 2.247(2) Å, and CeqSbCeq and OSbCax angles are 110.89(9)°–133.30(9)° and 177.05(7)°, respectively. The Sb…O=C intramolecular contacts are 3.151(7), 3.153(8) Å (IA), 2.985(8), 3.008(9) Å (IB), and 2.975(5) Å (II). Molecules IA and IB are conformation isomers, which differ from each other by the arrangement of carboxyl groups with respect to the equatorial plane.  相似文献   

15.
Wu-Song Li  Bing-Bing Wang  Yen Wei 《Tetrahedron》2007,63(36):8794-8800
Novel dendrons based on glycine and l-glutamic acid from the first generation (G1) to the third generation (G3) were synthesized and studied for their gelation properties by using transmission electron microscopy (TEM), atomic force microscopy (AFM), fluorescence, IR, circular dichroism (CD), and 1H NMR spectroscopy. It was found that the gelation capability of these dendrons increased from the first generation (G1) to the third generation (G3), and that G3 exhibited the highest efficiency in forming gels. Both the focal and peripheral groups of dendrons had great effects on the formation of organogels. Hydrogen bonding and π-π stacking interactions were proved to be the main driving forces to form the fibrous networks at low concentrations (0.5 wt %). Small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) measurements indicate that the xerogels of the second generation (G2) from ethyl acetate and ethanol, and G3 xerogel from CH2Cl2 all display lamellar structures with the interlamellar spacing of ca. 36.0 Å for G2 and 40.5 Å for G3, respectively.  相似文献   

16.
An Ag(I) complex with HL (I), AgL (AgC23H15O3, II), has been synthesized. Compounds I and II have been studied by X-ray diffraction. The crystals are monoclinic, I: space group P21/n, a = 10.459(2) Å, b = 12.354(2) Å, c = 13.390(3) Å, β = 96.67(3)°, Z = 4; II: space group P21/c, a = 10.764(2) Å, b = 10.683(2) Å, c = 15.939(3) Å, β = 101.57(3)°, Z = 4. The structural units of the crystal of I are neutral molecules with intramolecular hydrogen bonds. In structure II, the Ag2O6 dimeric groups and the ligands form infinite openwork layers perpendicular to the x axis and containing cavities. The layers are penetrated by channels with an oblong cross section. In the crystal of II, all intermolecular distances exceed the sums of the van der Waals radii of the corresponding atoms.  相似文献   

17.
Earlier NMR spectra of lanthanide complexes [Ln(18-crown-6)(NO3)3] have been analyzed by us (Babailov in Inorg Chem 51(3):1427–1433, 2012), where Ln3+ = La3+ (I), Ce3+ (II), Pr3+ (III) and Nd3+ (IV). The NMR signal assignment and conformational molecular dynamic have been found by 1D NOE and relaxation spectroscopy as well as on 2D NOESY and EXSY experiments at 170 K. In the present paper the 1H NMR method is used to study the features of paramagnetic properties of complexes IIV and [Eu(18-crown-6)(NO3)3] (V) at ambient temperature. The investigation was carried out by special method based on analysis of Δδ/z> on k(Ln)/z> (where k(Ln) is Bleaney’s constant, Δδ is paramagnetic contribution to the lanthanide-induced shifts). The obtained results indicate that the structure of the complexes (in CDCl3 and CD2Cl2) are very similar.  相似文献   

18.
A new copper(I) coordination polymer, [Cu((3,4-MeO-ba)2bn)I]n (1), using a bridging Schiff base ligand, N,N′-bis(3,4-dimethoxybenzylidene)butane-1,4-diamine, (3,4-MeO-ba)2bn, containing a flexible spacer (=N–CH2–CH2–CH2–CH2–N=) has been synthesized and characterized by elemental analyses (CHN) and FTIR spectroscopy, thermal analysis and powder X-ray structure analysis. In 1, Cu(I) ions are bridged by Schiff base ligands and iodine atoms forming 1D-chain. The thermal stability of 1 was studied by thermal gravimetric and differential thermal analyses. 1 is used to prepare CuO nanoparticles via solid state thermal decomposition in air and nanoparticles thus formed are characterized by scanning electron microscopy, transmission electron microscopy and powder X-ray diffraction techniques.  相似文献   

19.
Three Mn(II) complexes of [MnL(Bipy)(H2O)] n (I), [Mn3(Phen)2(HL)2(L)2]n (II), and [Mn(Phen)2(HL)(OH)] (III), where L = 4,4′-(2-acetylpropane-1,3-diyl)dibenzoic acid, Bipy = 2,2′-bipyridine, and Phen = 1,10-phenanthroline, were hydrothermally synthesized and characterized by single crystal X-ray diffractions, infrared spectroscopy, thermogravimetric analyses, and magnetic analyses. Complexes I and II are one dimensional (1D) coordination polymers which can form the supramolecules with the help of the intermolecular hydrogen bond interactions. Finally, the landé factors are simulated by magentochemical analysis to be 2.15 and 1.80 for I and II with S = 5/2, respectively.  相似文献   

20.
Four new fluorochromatouranylates, namely, K[UO2(CrO4)F] · 1.5H2O (I), Rb[UO2(CrO4)F] · 1.5H2O (II), Rb[UO2(CrO4)F] · 0.5H2O (III), and Cs[UO2(CrO4)F] · 0.5H2O (IV), have been synthesized, and their crystallographic characteristics have been determined. All the compounds crystallize in monoclinic system, space group P21/c, with the unit cell parameters a = 13.1744(5) Å, b = 9.4598(3) Å, c = 13.0710(4) Å, β = 103.746(1)°, Z = 4, R = 0.0235 (I); a = 13.5902(7) Å, b = 9.5022(4) Å, c = 13.2271(6) Å, β = 102.914(2)°, Z = 4, R = 0.0247 (II); a = 24.7724(8) Å, b = 12.6671(4) Å, c = 9.4464(3) Å, β = 97.661(1)°, Z = 8, R = 0.0448 (III); a = 25.725(1) Å, b = 12.8261(5) Å, c = 9.4929(4) β = 97.208(1)°, Z = 8 (IV). The pairs of compounds I and II and compounds III and IV are isostructural. Crystals of compounds I–III have been subjected to complete X-ray diffraction study. It has been established that the structures of compounds I–III are built of [UO2(CrO4)F] n n? layers, which are parallel to the (100) plane and linked into a framework by alkali-metal cations located between layers, together with water molecules. The effect of topological and geometric isomerism on the structural features of 34 known uranyl compounds of the AT3M2 crystallochemical group, to which the studied compounds I–III also belong, is discussed.  相似文献   

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