Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal

Thermodynamic parameters of complexation of naphto- 15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of static electric interaction and size selectivity between the host and the guest.

The Novel Benzo-15-Crown-5 with Palladium(II) Complex: [Na(B15CS)]_2,[Pd(SCN)_4]

A novel Pd(II) Benzo-15-crown-5 complex [Na(B15CS)]_2[Pd(SCN)_4] has been isolated and characterized by IR and X-ray diffraction analysis. The crystal structure belongs to monoclinic, space group P2_1,/n with cell dimensions, a = l.0164(6), b = l.3743(3), c = l.4987(7) nm, β = 95.248(6) °, V = 2.0847 'nm_3, Z = 2, F(000) = 944, R = 0.053, Rw = 0.072. The compound consists of two [Na(B15CS)]+ complex canons and a [Pd(SCN)4_]^(2-) complex anion. Each sodium ion is coordinated by five crown ether oxygen atoms and one N atom from the SCN group of [Pd(SCN)_4]^(2-) to form stable neutral complex.

Dioxygen affinities and catalytic oxidation performance of cobalt(Ⅱ) hydroxamates with benzo-15-crown-5 pendants

The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （ΔH^0 and ΔS^0） were calculated based on these （Ko2） values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.

STUDIES ON COMPLEXES OF RARE EARTHS WITH CROWN ETHERS(Ⅳ)SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF RARE EARTH NITRATES WITH 4'-BROMO-5'-NITROBENZO-15-CROWN-5

Six new solid complexes of macrocyclic polyether ligand 4′-bromo-5′-nitrobenzo-15-crown-5(L)with Uivalent rare earth nitrates having composition of RE(NO_3)_3·L·mCH_3CN·nH_2O(RE=L_a--Nd,m=n=0, RE=Sm,Bu,m=0.1,n=1,4)have been synthesized in acetonitrile or acetone.All the isolated complexes have been char- acterized by elementary analysis,IR and UV spectra,differential thermal and thermogravimetric analysis,X-ray powder diffraction analysis,molar conductance and measurementa of solubility in some general solventa.It shows that coordination number of the rare earth cation in the complexes of La,Ce,Pr and Nd nitrate is eleven.

STUDIES ON HETERO-MACROCYCLIC POLYETHER(1).THE SYNTHESIS OF 10-SELENA BENZO-15-CROWN-5

The synthesis of a new type of hetero-macrocyclic polyether 2,3-henzo-1,4,7,13-tetraoxa-10-selenacyclopentadeca-2-ene is deseribed.

STUDISS ON HETERO-MACROCYULIC POLYETHER(Ⅲ).THE SYNTHESES OF 10-TELLURABENZO-15-CROWN-5 AND ITS PLATINUM COMPLEX AS WELL AS ITS CATALYTIC BEHAVIOR IN HYDROSILYLATION

The syntheses of a new type of heteromacrocyclic polyether- 2,3-benzo-1,4,7,13-tetraoxa-10-telluracyclopentadeca-2-ene(L),and its pla- tinum complex(PtL_2Cl_2)were described.The catalytic activity of this complex for the hydrosilylation of olefins by triethoxysilane was investigated.

STUDIES ON HETERO-MACROCYCLIC POLYETHER (Ⅱ). THE SYNTHESIS OF PLATINUM COMPLEX OF 10-SELENABENZO-15-CROWN-5 AND ITS CATALYTIC BEHAVIOR IN HYDROSILYLATION

The title complex (PtL_2Cl_2) was synthesized by reacting 10-selenabenzo-15-crown-5 (L) with potassium chloroplatinite. Its catalytic activity for the hydrosilylation of olefins by triethoxysilane, was investi gated.

Synthesis and Crystal Structure of 〔Na(N-(p-chlorophenyl)aza-15-crown-5)-(Et_2O)〕_2 (Na_2W_(0.5)Mo_(7.5)O_(26))

[Na (N- (p-chlorophenyl ) aza-15--crown--5 ) (Et2O )]2 (Na2W0.5 Mo7.5 O26), Mr= 2119. 4, monoclinic, space group P21/c, a= 17. 803(4), b= 13. 674 (3), c= 14. 610(3), β= 112. 33(3)°, V=3290(1) A3, Z= 2, Dc= 2. 139 g/cm3, μ= 1.704 mm-1, F (000) = 2079, R = 0. 026, Rw= 0. 030. The supermolecular complexconsists of one [Na2W0.5Mo7.5O28)2- anion in which only two Mo atoms are replaced byW in 25% (M= l/4W+3/4Mo) and the two Na+ are linked symmetrically to neighbouring [W0.5Mo7.5O26]4- units on the right and the left respectively and two complexcanons in which each Na+ deviates from the plane of the four ether oxygens and is coordinated to every hetero--atom in the crownether ring, and is also coordinated to the Oatom of Et2O.

Metal Ion Enhanced Phosphorescence of 2,3-Naphtho-10-aza-15-crown-5: A Possible Molecular Photonic Operator

A novel crown ether, 2,3-naphtho-10-aza-15-crown-5 (NAC) was synthesized.This compound does not show strong fluorescence and phosphorescence due to photoinducedintramolecular electron transfer from the nitrogen lone pair of electrons to the singlet excitedstate of the naphthalene chromophore. Complexation with heavy-metal ions results in the quenching ofthe fluorescence and enhancement of the phosphorescence significantly. These observations wereinterpreted in terms of the binding interactions, between the nitrogen lone pair electrons and themetal cation, which prevent photoinduced intramolecular electron transfer, and the heavy-atomeffects which induce quenching of the fluorescence and enhancement of the phosphorescence. Theseazacrown and heavy-metal-based systems could be useful as potential chemical sensors and molecularphotonic devices.

Construction of a PVC based 15-crown-5 electrochemical sensor for Ag(Ⅰ) cation

The macrocyclic ligand,15-crown-5,was used as an ionophore for fabrication of a polyvinyl chloride（PVC） based membrane sensor for Ag（Ⅰ） cation.For construction of the Ag（Ⅰ） cation selective electrode the best response characteristics were obtained using the composition： 15-crown-5/PVC/o-nitrophenyloctylether（NPOE）/sodium tetraphenyl borate（NaTPB） in the percentage ratio of 5.6/30/60.5/3.9（w/w/w/w）.The electrochemical sensor shows a linear dynamic range 1.0 10 7–1.0 10 1mol/L and a Nernstian slope of 58.9 0.5 mV/decade with a detection limit of 8.09 10 8mol/L for Ag（Ⅰ） cation.It has a fast response time of 〈10 s and can be used for at least 8 weeks without any considerable divergences in its potential response.It was successfully used as an indicator electrode in potentiometric titration of Ag（Ⅰ）cation with I and Cl anions and also for the determination of this metal cation in radiology waste water.

ESR study on some copper(Ⅱ)complexes of bis(4'-benzo-15-crown-5)

ESR measurements have been carried out for some copper(Ⅱ) complexes of bis(4'-ben- zo-15-crown-5) at 77 K.The results of ESR spectrometric titration indicated that the binuclear com- plexes were prepared in the present system.The binuclear complexes revealed characteristic ESR g-anisotropies (gZ<gX,gY) which are typical of the copper(Ⅱ) complexes with a 3d_Z^2 ground state doublet.However,in this case,the innermolecular copper(Ⅱ)-copper(Ⅱ) spin interaction was not observed.ESR measurements also showed that a small amount of the sandwich type copper(Ⅱ) com- plexes were formed in the presence of excess bis (4'-benzo-15-crown-5).A reasonable explanation was given for the ESR results.

Dioxygen Affinities and Biomimetic Catalytic Performance of Transition-metal Complexes with Crowned Bis-Schiff Bases

The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.

Design, Synthesis and Properties of Novel C60-Crown Dyads by 1,3-Dipolar Cycloaddition

Based on the 1,3-dipolar cycloaddition of azomethine ylide generated in situ from aldehyde and sarcosine attached to C60,two novel benzo-15-crown-5/C60 dyads with a different linking chain in each were designed and synthesized in yields of 30％ and 38％,respectively.It was found that their UV-Vis absorption spectra could be regulated hypsochromically by metal ions complexed.The long and soft linking chain was favorable for cooperate interaction of crown ether unit and C60 unit.

Cobalt(II) Salen Complex with Two Aza-crown Pendants and Its Analogues as Synthetic Oxygen Carriers

Salen with two aza-crown ether pendants H2L1 and its analogues H2L2--H2L4 were successfully synthesized starting from benzo-10-aza-15-crown-5 (BN15C5) or morpholine. Their structures were characterized by IR, MS, H-1 NMR and elemental analysis, and were confirmed by X-ray diffraction analysis of H2L1. Moreover, the saturated oxygen uptake of their cobalt(II) complexes CoL1-CoL4 in diethyleneglycol dimethyl ether was determined at different temperature. The oxygenation contants ( K-O2) and thermodynamic parameters (DeltaHdegrees and DeltaSdegrees) were calculated. The modulation of O-2-binding capabilities by pendant substituents were investigated as compared with the parent Schiff base complex CoL5 (CoSalen). The results indicate that the dioxygen affinities of CoL have been much more enhanced by aza-crown pendants than that by morpholino pendants, and the O-2-binding capabilities of CoL1 and CoL2 with aza-crown pendants would also be enhanced by adding alkali metal cations.