Abstract New types of o-phenylene-bridged polythioethers tethered with extremely bulky aryl groups at their terminal sulfur atoms, such as TbtS(o-Phen)S(o-Phen)S(o-Phen)STbt (1) and TbtS(o-Phen)S(o-Phen)SS(o-Phen)S(o-Phen)STbt (2) (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, o-Phen = o-phenylene), were synthesized and subjected to the complexation with several kinds of late-transition metals. In the case of polythioether 1, the reaction with RhCl3·3H2O in benzene/EtOH resulted in the formation of a unique bimetallic complex, in which a part of ligand 1 is lost and the resulting sulfur atom is directly bound to the other Rh metal center. Interestingly, similar treatment of 1 with IrCl3·3H2O afforded ethyl-coordinated mononuclear Ir complex. Furthermore, 1 underwent complexation with Na2PdCl4 in EtOH to give the corresponding square planar dichloropalladium complex coordinated with two inner sulfur atoms of 1, while the S6-ligand 2 reacted with excess of Pd(PPh3)4 in benzene to afford a quite interesting trinuclear Pd complex multi-step metal insertion reactions. 相似文献
Nitro-substituted phenolic ethers were successfully selectively dealkylated. The directing effect of the nitro group is supported by the excellent regioselectivities and good yields. These reactions demonstrate that the complexation of AlCl3 with the phenolic nitro group is stronger than with the phenolic ether alone. The mechanism for the selective dealkylation directed by the nitro group is proposed. 相似文献
ABSTRACT This work presents unusual spectral behavior of poly(tricyanovinyl dimethylaniline) (1) in dilute solutions. A new conjugated polymer(1) was prepared from p-(tricyanovinyl)N,N-dimethylaniline via the use of a methylglucopyranoside reagent. It is observed that dilute solutions of 1 exhibit spectral features associated with aggregation. The associative interaction is studied by changing the salt concentration of LiBr in DMF solution, by changing the concentration of 1, and by varying the solvents. The association modifies the visible spectrum of 1 in dilute solution. Spectra of 1 in DMF solution exhibit an intense absorption maximum at 429 nm, which can be assigned to the side group, with tailing past 700 nm. With increasing concentration, a new absorption band arises between 480 nm and 700 nm. LiBr dissociates the aggregate to decrease the additional spectral features. The visible spectrum of 1 varies in different solvents. The spectrum of 1 in chloroform solution exhibits two maxima at 490 nm and 550 nm. The associative interaction presumably arises from a dipole–dipole interaction among pendant side groups. In DMF solution of 1 in the presence of p-chloranil, the spectrum shows a maximum at 429 nm with a distinct shoulder near 520 nm which does not orginate from 1 and p-chloranil(CA) itself. 相似文献
Abstract Novel chromogenic 21-membered crown ether having an intraannular azo and hydroxy subunits has been used as a complexing reagent for alkali metal cations. The complex formation was detected by visible spectroscopy and formation constants were calculated. The most pronounced spectral changes were observed for lithium ion. 相似文献
Abstract The Cs+ selectivity of some calix-crown ligands makes them excellent candidates for use in separation systems such as liquid membranes. Separation performance can be understood and predicted from thermodynamic data for cation complexation. We have therefore determined the log K, ΔH and ΔS for the interaction of Na+, K+, Rb+, Cs+ and NH4+ with didodecyl-calix[4]arene-crown-6 in acetonitrile at 25°C by titration calorimetry. The ligand is strongly selective for Cs+, and the selectivity trend results entirely from the enthalpy contribution, with entropy effects opposing the trend. These results are discussed in light of some corresponding data obtained by other researchers with similar ligands. 相似文献
By reacting mono-substituted or 1,3-bi-substituted [2-(p-formylphenyloxy)ethyloxy]-p-tert-butylcalix[4]arene (3 or 4) with hydrazine hydrate in ‘1+2’ or ‘2+2’ condensation mode, novel benzalazine-bridging biscalix[4]arenes 5 and 7 were conveniently obtained in the yields of 76 and 81%, respectively. Condensation of compound 4 and salicylide hydrazone gave a novel calix[4]arene benzalazine derivative 6 in the yield of 85%. The structures and conformations of all new compounds were characterised by elemental analyses, ESI-MS, 1H NMR and 1H–1H COSY techniques. Biscalix[4]arene 7 adopts a symmetrical cone conformation with tube cavity. The liquid–liquid extraction experiment showed that all new hosts possessed excellent complexation abilities towards soft metal cations. Compound 7 exhibited high complexation selectivity towards Ag+. The Ag+/Na+ and Ag+/Hg2+ extraction percentages of host 7 were as high as 73.1 and 54.9, respectively. The UV–vis spectra complexation experiments revealed that the complexation constant of receptor 7 with Ag+ was 1.9 × 105 M? 1 and the 1:1 stoichiometry of receptor 7–Ag+ complex was formed. The 1H NMR spectra complexation experiments suggested that Ag+ was bound in a cavity composed of two benzalazine groups on bridging chains. 相似文献
The structures and binding energies of complexes formed between tris-ureido-calix[5]crown 1 and n- and 2-phenylethylammonium chloride have been determined by density functional calculations. Density functional theory analysis shows that the heteroditopic receptor 1 binds organic salt species with positive cooperativity. 相似文献
In this study, we investigated the binding behaviours of three water-soluble p-sulfonatocalixarenes with four cinchona alkaloids in aqueous and phosphate buffer solutions (pH 7.2 and 2.0). The complexation stability constants obtained by fluorescence titrations were comparatively discussed from several aspects: host cavity, pH effect and ionic strength. Among three hosts, p-sulfonatocalix[4]arene (SC4A) forms the most stable complexes with cinchona alkaloids, especially in acidic aqueous conditions. Furthermore, SC4A was elected as model drug carrier for cinchona alkaloids, where solubilisation by the complexation of SC4A and mimic release from the calixarene cavity in the presence of negatively charged micelles were initially studied. 相似文献
Amylose and polytetrahydrofuran (PTHF) are mixed in an aqueous solution to form inclusion complexes. DSC shows that immediate mixing results in complexes having lower melting temperatures compared with complexes prepared with longer mixing times. The washed complexes melt at higher temperatures compared with the corresponding unwashed complexes. XRD indicates that amylose–PTHF complexes diffract similar to amylose–fatty acids complexes (V6I‐amylose helices), with additional diffractions correlating with amylose–alcohol complexes (V6II‐amylose helices). This suggests that the structure of amylose–PTHF complexes is an intermediate or a mixture between V6I‐ and V6II‐amylose. This shows that, besides residing inside the amylose helices, some PTHF chains are located in between the amylose helices.