首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Fast-atom bombardment (FAB) mass spectrometry was used to investigate the interaction of proton and alkali metal ions with dinucleotide analogs such as T-n-T (T = thymine moiety, n = polyether chain, e.g., triethylene, tetraethylene, pentaethylene, and hexaethylene ether 1–4), A-n-T (A = adenine unit 5–8), and T-n-OMe (9–12) in 3-nitrobenzyl alcohol matrix. The [M + H]+ ion is the most abundant ion for the A-n-T series, whereas in 1–4 and 9–12 the (TC2H4)+ ion is the most abundant. Formation of [M + H -C2H4O]+ ions, a characteristic fragmentation of crown ethers under electron ionization, is observed for compounds 1–12 and is more pronounced in 6 and 7. An abundant [M ? H]? ion is observed for all the compounds studied under negative ion FAB due to the presence of the (-CO-NH-CO-) group of thymine, an indication of existence of intramolecular H bonding. The FAB mass spectra of 1–12 with alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) showed formation of abundant metal-coordinated ions ([M + Met]+ and [TC2H4 + Met]+). Compounds 3, 4, 6, 7, and 10–12 showed ions due to the substitution of the thymine moiety by a hydroxyl group ([M + Met ? 108]+, Met = metal ion). For compound 3 alone, substitution of two thymine groups ([M + Met - 216]+) was observed. Metastable ion studies were used to elucidate the structures of these potentially significant ions, and the ion formule were confirmed with high resolution measurements. Selectivity toward metal complexation with ligand size was seen in the T-n-T and A-n-T series and was even more pronounced in A-n-T series. These dinucleotide analogs fall in the following order of chelation of alkali metal ions, acyclic glymes < dinucleotide analogs (acyclic glymes substituted with nitrogen bases) < crown ethers, which places them in perspective as receptor models.  相似文献   

2.
The lower rim functionalized hexahomotrioxacalix[3]arene triamide 4 with cone-conformation was synthesized from triol 1 by a stepwise reaction. The different extractability for alkali metal ions, transition metal ions, and alkyl ammonium ions from water into dichloromethane is discussed. Due to the strong intramolecular hydrogen bonding between the neighboring NH and CO groups in triamide 4, its affinity to metal cations was weakened. Triamide 4 shows a single selectivity to n-BuNH 3 + . The anion complexation of triamide 4 was also studied by 1H NMR titration experiments. Triamide 4 binds halides through the intermolecular hydrogen bonding among the NH hydrogens of amide in a 1:1 fashion in CDCl3. The association constants calculated from these changes in chemical shifts of the amide protons are K a = 223 M?1 for Cl? and K a = 71.7 M?1 for Br?. Triamide 4 shows a preference for Cl? complexation than Br? complexation.  相似文献   

3.
New benzo-15-crown-5 derivatives containing nitro, amine and imine groups were prepared. Nitro compound (1) was prepared after the reaction?4′,5′-bis(bromethyl)benzo-15-crown-5 and o-nitrophenol in the presence of NaOH. After reduction process by using hydrazine hydrate and Pd/C amine compound (2) was formed. New crown ether imine compounds (35) were synthesized by the condensation of corresponding crown ether diamine (2) with salicylaldehyde derivatives. Sodium complexes of the crown compounds (1a5a) form crystalline 1:1 (Na+: ligand) complexes with sodium perchlorate. Nickel(II) complexes (3b5b) with 1:1 (Ni2+:ligand) stoichiometries were also been synthesized from the Schiff bases (35). The results indicated that the Schiff base ligands coordinated through the azomethine nitrogen and phenolic oxygen. The extraction ability of compounds (1, 3, 4 and 5) were also evaluated in chloroform by using several alkali and transition metal picrates such as Li+, Na+, K+, Cr3+, Mn2+, Ni2+, Cu2+, Zn2+ and Pb2+.  相似文献   

4.
A series of new benzo-15-crown-5 derivatives (16) containing formyl and imine groups were prepared. New formyl crown ethers (1 and 2) were prepared by reaction of 4′,5′-bis(bromomethyl)benzo-15-crown-5 with 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) and 2-hydroxy-5-methoxybenzaldehyde in the presence of NaOH. New Schiff bases (36) were synthesized by the condensation of corresponding aldehydes with 1,3-diaminopropane and 1,4-diaminobutane. Sodium and potassium complexes (1a6a and 1b6b) of the crown compounds forming crystalline complexes of 1:1 (Na+:ligand) and 1:2 (K+:ligand) stoichiometries were also synthesized. The structures of the aldehydes 1 and 2, imines 36 and complexes (1a3a and 1b3b) were confirmed on the basis of elemental analyses, IR, 1H- and 13C-NMR, and mass spectroscopy.  相似文献   

5.
It has been shown that N,N’-diaryldiaza-18-crown-6 ethers with p-dimethylamino-and p-methoxy groups in the benzene ring (aryl is 4-Mc2NC6H4) (I) and 4-MeOC6H4 (II) form complexes with potassium and barium salts. The influence of these salts on the UV and 1H NMR spectra of crown ethers I and II has been studied. The stability constants (logβ) of the complexes increase in the series II · Ba(ClO4)2 (2.0), I · Ba(ClO4)2 (2.3), II · KBr (2.8), I · KBr (3.0). N,N’-bis(4-dimethylphenylamine)diaza-18-crown-6 (L, I) and its complex with barium perchlorate Ba(ClO4)2 · L (III) are characterized by X-ray crystallography. The crystals of I are monoclinic: a = 13.778(2) Å, b = 5.9731(9) Å, c = 17.542(3) Å, β = 106.65(1)°, V = 1383.1(4) Å3, Z = 2, space group P21/n, R = 0.0374 for 990 reflections with I > 2σ(I). The crystals of III are monoclinic: a = 17.275(4) Å, b = 8.017(2) Å, c = 26.935(4) Å, β = 100.47(2)°, V = 3669(1) Å3, Z = 4, space group C2/c, R = 0.0320 for 1897 reflections with I > 2σ(I). The molecules of I and III are centrosymmetric. In III, the Ba atom is in the center of substituted diaza-18-crown-6 (DA18C6). The Ba atom is coordinated by all six donor atoms of diaza-18-crown-6 (av. Ba-O, 2.779(3) Å; Ba-N, 3.004(4) Å) and four oxygen atoms of two asymmetrically bound perchlorate groups (Ba-O, 2.832(4) and 3.031(4) Å) arranged below and above the plane of substituted diaza-18-crown-6. The conformations of the macrocycle in free and coordinated L are different.  相似文献   

6.
The lower rim functionalized cone-hexahomotrioxacalix[3]arene tris(2-pyridylamide) derivatives cone- 3 and cone-7 having the hydrogen bonding groups and 2-pyridyl groups were synthesized from triol 1 by a stepwise reaction. Extraction data for alkali metal ions, transition metal ions, and alkyl ammonium ions from water into dichloromethane are discussed. Due to the strong intramolecular hydrogen bonding between the neighboring NH and CO groups, their affinities to metal cations were weakened. The complexation modes of cone-3 and cone -7 with n-BuNH3Cl and AgSO3CF3 were also demonstrated by 1H NMR titration in CDCl3. Tris(2-pyridylamide) derivatives cone-3 and cone-7 can complex with n-butyl ammonium ion and silver cation at the same time to form the heteroditopic complexation.  相似文献   

7.
Two new chiral glucopyranoside-based crown ethers incorporating acridine fluorescent signalling units, 15-membered ligand 1 and 21-membered ligand 2 were synthesized. Their complexation properties toward alkali and alkali earth metal ions, and their enantioselectivity towards chiral ammonium salts were studied by absorption and fluorescence spectroscopic experiments. Macrocycle 1 formed 1:1 complexes with all the metal ions selected and the stability constants were low (lg K < 2.3). The cavity-size of 2 allowed only the complexaton of organic ammonium ions. Crown 2 showed chiral discrimination in case of all the four ammonium salts used as model guest compounds; the highest enantioselectivity (K(R)/K(S) ~3) was observed for the enantiomers of phenylethyl ammonium perchlorate. Ligand 2 forms much more stable complexes with metal ions; the highest stability constant was obtained for the Ca2+ complex (lg K = 6.15). The coordination of metal ions by ligand 2 was accompanied by marked fluorescence enhancement, whereas the binding of ammonium ions by the same species resulted in significant fluorescence quenching.  相似文献   

8.
The hydrothermal reactions of nitrate or chloride salts of Co(II), Zn(II), Cd(II), Hg(II) and Ag(I) with an unsymmetrical benzotriazole derivative 1H-1,2,3-benzotriazole-1-propionic acid (Hbtap) afforded five new metal–organic coordination polymers with formula of [M(btap)2(H2O)2] n (M = Co 1, Zn 2, Cd 3), [Hg(btap)Cl] n (4) and {[Ag(btap)]·H2O} n (5), which were characterized by X-ray diffraction and spectroscopic methods. The anionic btap? ligands in these complexes assume the same anti conformation, but show different coordination behaviors toward transition metal ions. Complexes 1, 2 and 3 are isostructural and reveal infinite one-dimensional (1D) looped-chain structures constructed by hexacoordinated metal centers and 2-connected btap? bridges. Complex 4 features 1D zigzag polymeric arrays, which are interlinked with each other resulting in a chiral three-dimensional (3D) 4-connected framework. In complex 5, the 3-connected ligands join Ag(I) atoms into a 1D ribbon motif. The photoluminescence spectra of three d10 metal complexes 2, 3 and 4 were measured at room temperature. The emission peaks of these complexes resemble that of the free ligand and can be ascribed to the intraligand π–π* transitions.  相似文献   

9.
This study presents the selective chloromethylation of calix[4](aza)crown ethers 2ac, using chloromethyl n-octyl ether and SnCl4 in chloroform at room temperature in good yield for the first time. Chloromethylated products 2ac are used as key intermediates to synthesize new water-soluble p-phosphonato calix[4](aza)crown ethers 5ac. Liquid–liquid phase extraction and phase solubility studies with poor water soluble drug molecules such as nifedipine, niclosamide and furosemide are performed to evaluate their binding properties. Among the studied drugs, furosemide was the most effectively dissolved drug by p-phosphonato calix[4](aza)crown ethers 5ac in water.  相似文献   

10.
The reactions of 3(5)-(4-methoxyphenyl)-5(3)-phenyl-1H-pyrazole (L 1 ) with nitric acid and 5-(4-benzyloxyphenyl)-3-(furan-2-yl)-1H-pyrazole(L 2 ) with hydrochloric acid produced [HL 1 · NO3] (Salt-1) and [HL 2 · Cl] (Salt-2). The structures of Salt-1 and Salt-2 were determined by single crystal X-diffraction. In Salt-1, HL 1 showed [2 + 2] binding of NO3 ? ions in the solid state to form dimer architecture with R 1 2 (4) and R 4 4 (14) graph sets. An anion directed one-dimensional anion-assisted helical chain with active participation of the chloride ion and protonated pyrazole via N–H···Cl hydrogen bonding in Salt-2. In addition, the protonated HL 2 molecules interacted with each other through weak C–H···π interactions resulting in the formation of another one-dimensional helical chain.  相似文献   

11.
Two complexes are synthesized: diaquabromo(18-crown-6)rubidium [RbBr(18-crown-6)(H2O)2] (I) and triaqua(18-crown-6)barium dibromide monohydrate [Ba(18-crown-6)(H2O)3]2+ 2Br? · H2O (II). The orthorhombic structure of compound I (space group Pnma, a = 10.124 Å, b = 15.205 Å, c = 12.544 Å, Z = 4) and the monoclinic structure of compound II (space group C 2/c, a = 17.910 Å, b = 10.315 Å, c = 14.879 Å, β = 123.23°, Z = 4) are determined by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.063 (I) and 0.042 (II) for all 2293 (I) and 3363 (II) independent measured reflections (CAD-4 automated diffractometer, λMoK α). The complex molecule [RbBr(18-crown-6)(H2O)2] in compound I and the randomly disordered cation [Ba(18-crown-6)(H2O)3]2+ in compound II are of the host-guest type: their Rb+ or Ba2+ cation (its coordination number is nine) is located in the cavity of the 18-crown-6 ligand and coordinated by all six O atoms. In structure I, the coordination polyhedron of Rb+ is a distorted hexagonal pyramid with a triple apex at the Br? ligand and two O atoms of the water molecules. In structure II, the Ba2+ polyhedron is a distorted hexagonal bipyramid with one apex at the O atom of the water molecule and the other split apex at two O atoms of water molecules.  相似文献   

12.
The coordination chemistry of a rigid periodinated ligand, 2,3,5,6-tetraiodo-1,4-benzenedicarboxylic acid (H2BDC-I4), with a series of transition metal ions has been explored to afford five new coordination polymers {[M(BDC-I4)(MeOH)4](H2BDC-I4)(MeOH)2} n (M?=?ZnII for 1, CdII for 2, CoII for 3 and MnII for 4) and {[Mn(BDC-I4)(MeOH)4](DMF)} n (5). All these complexes have been characterized by elemental analysis, IR spectroscopy, thermogravimetric (TG) analysis, and X-ray crystallography. Single-crystal X-ray diffraction reveals that complexes 1?C4 are isostructural and have a one-dimensional chain structure. Upon the addition of the solvent DMF, the infinite linear chain array in 4 is converted to a 1-D wave-like chain motif in 5 with a different space group ( $ P\overline{1} $ for 4 and P21/c for 5). The difference between structures 1?C4 and 5 can be attributed to the coordination mode of carboxylate changing from trans to cis fashion. The ZnII and CdII complexes 1 and 2 display similar emissions in the solid state, which essentially are intraligand transitions.  相似文献   

13.
A series of 1,2,3-triazole-linked calix[4]arene ionophores comprised of different O-donor groups (OH, COOEt, CONEt2) attached either to the lower rim of calix or to the triazole moieties were synthesized to explore their ion-selectivity for the first time in potentiometric transduction. Plasticized PVC membrane electrodes (ISEs) were fabricated, and their potentiometric selectivities were measured toward a series of mono- and divalent metal ions. Structure-ion-selectivity relationship and the structural requirements of the coordination sphere for selective binding were established. ISEs made of calix[4]arene-bis-triazoles were found generally to exhibit distinct Ag+ selectivity in the order 3 ≈ 4 > 2 > 1, indicating the beneficial effect of the carboxamide or ester groups in the complexing site. In contrast, calix[4]arene-tetratriazole 5 comprised only sp 2 N-donor atoms displayed excellent Cu2+ selectivity over a series of alkali-, alkaline earth- and transition metal ions. A unique feature of the outstanding Ag+ selective electrodes made of 3 and 4 was recognized and suggested their potential application as Na+ ISEs in systems not containing silver ions. Further, the potential use of competitive ESI-MS experiments for screening the binding affinities of ionophores 36 to different metal ions was also demonstrated.  相似文献   

14.
Chromene derivatives bearing oxymethyl-12-crown-4 (1), -15-crown-5 (2), -18-crown-6 (3) ether moieties, and non-cyclic analogue (4) were synthesized, and their metal ion binding properties and photochromism were examined. NMR titration with alkali metal ions revealed that 1 formed a 1:2 complex (metal ion: ligand) with Na+, while Li+ afforded a 1:1 complex of 1. In cases of K+ and Rb+, the complexes were a mixture of 1:1 and 1:2 complexes, but the formation of 1:1 complex was observed again with Cs+. Under UV irradiation, however, the complex stoichiometry of 1 with all alkali metal ions was 1:1. As a comparison of NMR spectra between the Li+ and Na+ complexes of 1 indicated considerable upfield shift for the chromene moiety of the Na+ complex, π-π stacking of the chromene moiety seems to induce formation of the 1:2 complex. These results indicate that the chromene moiety is not only to show photochromism but also to induce aggregation to form the 1:2 complex resulted in switching of the complex stoichiometry by UV irradiation. The formation of 1:2 complex appeared only with 1 because flexibility of the crown moieties for 2 and 3 interfered the formation of 1:2 complex. Studies on photochromism in the presence of a metal ion demonstrated that the chromene derivatives bearing crown ether moieties show ion-responsive photochromism depending on the metal ion binding ability of their crown ether moieties.  相似文献   

15.
Two complexes, namely, (18-crown-6)bis(perchlorato-O,O′)strontium (I) and (18-crown-6)bis(perchlorato-O,O′)barium (II), are synthesized. Their crystal structures are determined by X-ray diffraction analysis. The structures of I (space group P21/c, a = 15.266 Å, b = 11.080 Å, c = 13.235 Å, β = 109.20°, Z = 4) and II (space group P21/n, a = 8.330 Å, b = 11.202 Å, c = 11.752 Å, β = 98.38°, Z = 2) are solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.077 (I) and 0.041 (II) against 3714 (I) and 2478 (II) independent reflections (CAD-4 diffractometer, λMoK α radiation). Complex molecules [Sr(18C6)(ClO4)2] in the structure of I and [Ba(18C6)(ClO4)2] in II (in the inversion center)—are of the host-guest type. The Sr2+ or Ba2+ cation is localized in the center of a cavity of the 18-crown-6 ligand and coordinated by its all six O atoms. In compounds I and II, the coordination polyhedron of the Sr2+ and Ba2+ cations (coordination number 10) can be described as a distorted hexagonal bipyramid with two bifurcated vertices at two O atoms of two ClO 4 ? ligands, which are disordered in I and II and each of them has two orientations.  相似文献   

16.
Complexation of styryl dyes containing theN-phenylaza-15-crown-5 fragment (trans-2a,b) with Ca2+ ions in MeCN was studied. Unlike cationic dyetrans-2a, betainetrans-2b forms both complexes of 1∶1 stoichiometry and aggregates consisting of four dye molecules and one Ca2+ ion. Cation-induced aggregation was observed also for the analog of dyetrans-2b, which contains a dimethylamino group instead of an azacrown ether fragment (trans-3). Apparently, the interaction between a metal cation and sulfo groups of moleculestrans-2b ortrans-3 makes the main contribution to the stability of aggregates. The dependence of the stability of aggregates on the nature of the metal cation was studied.  相似文献   

17.
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   

18.
Four novel complexes of 2,4-dithiouracil (pyrimidine-2,4(1H,3H)-dithione, DTU) with 18-membered benzo- and dibenzo-crown ethers were synthesized in approximately the same conditions and studied by single crystal diffraction. Hydrogen bonding was observed to be the most important for the complexation in the solid state but π–π interactions also contribute to it. The crystalline monohydrates of the 1:1:1 stoichiometry are recorded for 4-bromo- and 4-nitrobenzo-18-crown-6 (complexes 1 and 2), while complexes with [2.4]dibenzo- and thia[1.5]dibenzo-18-crown-6 (complexes 3 and 4) represent anhydrous adducts of the 2:2 ratio. The crystal structures reveal three supramolecular structural motifs: the alternative chain for the ternary complex 1 and two types of capsules for complexes 2?4 where the DTU dimers are encapsulated inside the space restricted by two crown molecules.  相似文献   

19.
A number of p-tert-butylcalix[4]arene thioamides were synthesized and characterized by 1H-NMR and elemental analysis. Compounds 15 are O-substituted derivatives with –CH2–C(=S)–N–X groups, where NX = morpholidyl, NEt2, NHC2H4Ph, NHCH2Ph and NHEt, respectively. The X-ray structures of the ligands 1, 3, 5 and of the complex 3·Pb(ClO4)2, (compound 6), are presented and their slightly distorted cone conformation is established. The influence of the nature of the thioamide functions (secondary or tertiary) on the extractability of some selected metal cations was investigated. Whereas all these calixarenes show the highest extraction level for Ag+, tertiary thioamides are more efficient extractants for Pb2+ than secondary thioamides.  相似文献   

20.
The ion mobility in new fluoride glasses (mol %) 45ZrF4 · 25BiF3 · 30MF (I) (M = Li, Na, K), (70 - x)ZrF4 · xBiF3 · 30LiF (II) (15 ≤ x ≤ 35), and 45ZrF4 · (55-x)BiF3 · xMF (III) (M = Li, Na; 10 ≤ x ≤ 30) has been studied by 7Li, 19F, and 23Na NMR in the temperature range 250–500 K. The character of ion motion in bismuth fluorozirconate glasses I and III is determined by temperature and the nature and concentration of an alkali-metal cation. Major type of ion mobility in glasses I–III at temperature 400–440 K are local motions of fluorine-containing moieties and diffusion of lithium ions (except for the glass with x = 10). The factors responsible for diffusion in the fluoride sublattice of glasses I have been determined. Sodium ions in glasses I and III are not involved in ion transport.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号