Selective extraction of Fe3+ by a polymeric calix[4]arene

A polymeric compound containing more than one calixarene molecule was synthesized by reacting the oligomer ( 2 ) with 25,26,27-tribenzoyloxy-28-hydroxy calix[4]arene. After basic hydrolysis of 3a , the polymeric calixarene ( 3b ) was utilized for selective extraction of some metal cations from aqueous phase to organic phase. It was found that the compound ( 3b ) was selective toward Fe³⁺ from an aqueous solution containing Cu²⁺, Ni²⁺, Co²⁺ and Fe³⁺ cations. The mechanism of the extraction process was discussed. © 1994 John Wiley & Sons, Inc.     

The First Calcium(II) Complex with the Saccharinate Ligand: Synthesis,Crystal Structure,Spectral and Thermal Characterization of Trans—diaquabis[(2—hydroxyethyl)pyridinium]bis(saccharinato)calcium(II) Disaccharinate, [Ca(sac)2(H2O)2(Hpyet)2](sac)2

A new calcium(II) complex of the saccharinate ligand (sac) with 2—hydroxyethylpyridinium (Hpyet) was synthesized and characterized by elemental analysis, FT—IR spectroscopy, thermal analysis and single crystal X—ray diffractometry. The [Ca(sac)₂(H₂O)₂(Hpyet)₂](sac)₂ complex crystallizes in the triclinic space group (P1¯) with the cell dimensions a = 7.4360(7)Å, b = 12.5263(12)Å, c = 12.8329(13)Å, α = 82.534(8)°, β = 75.202(8)° and γ = 89.662(8)° (293 K). The title complex consists of a complex cation and two sac anions. In the complex cation, the calcium(II) ion is six—coordinate, bonding to two aqua ligands, two Hpyet ligands andtwo sac ligands located in the trans positions. Two of the sac ions are coordinated to the calcium(II) ion through the carbonyl O atom, while the other two remain outside the coordination sphere as the counter—ions. Thermal decomposition of the complex in air results in elimination of aqua, Hpyet, and sac ions, respectively.     

Synthesis of novel crown ethers. Part 1. Coumestan and coumestan analog derivatives of crown ethers

The presented ethylenedioxy compounds5a,5d,6a and6c are examples of novel cyclic ethers, while macrocyclic polyethers represent new crown ether analogues. New coumestan-crowns5a-f, derivatives of 6,7-dihydroxy-3,4-dihydro-2H-dibenzofuran-1-one and 6,7-dihydroxy-3,3-dimethyl-3,4-dihydro-2H-dibenzofuran-1-one6a-e were synthesized from the correspondingo-dihydroxy compounds3a-b,4a-b and ditosylates or dichlorides of di- or triethylene glycol in the presence of K₂CO₃, in DMF/H₂O (15/1) solutions at 65–75 °C for 35 hours. The structure of the macrocyclic ethers obtained were confirmed by¹H-NMR,¹³C-NMR, IR spectra and elemental analyses.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995.     

Development of molecularly ımprınted polymer based quartz crystal mıcrobalance nanosensor for the determınatıon of tryptophan

ABSTRACT

In this study, a quartz crystal microbalance (QCM) nanosensor was prepared to detect tryptophan. QCM nanosensor was prepared through the formation of tryptophan memories on the gold surface of QCM electrode using Methacryloylamidohistidine-Cu(II)-tryptophan ([MAH-Cu(II)]-tryptophan) pre-organised monomer system. The designed pre-organised monomer system was characterised by use of Fourier Transform Infrared (FTIR) and Atomic Force Microscope (AFM) was used to characterise the QCM nanosensors. After the characterisation studies, imprinted and non-imprinted sensors were connected to QCM system to determine the binding of the target molecule, selectivity and the detection of the amount of target molecule in real samples. The results showed that the imprinted QCM nanosensor had high selectivity for tryptophan.     

A One‐dimensional Lead(II) Coordination Polymer with Bridging Saccharinate and 2‐Aminomethylpyridine Ligands: Synthesis,IR Spectra,and Crystal Structure of [Pb(ampy)(μ‐sac)2]n

A complex with eight‐coordinate lead(II ) atom and saccharinate (sac) and 2‐aminomethylpyridine ligands was characterized by IR, elemental analysis and X‐ray crystallography. The lead(II ) complex crystallizes in the monoclinic crystal system with space group P2₁/c. The single crystal X‐ray analysis shows that the complex is a coordination polymer, [Pb(ampy)(μ‐sac)₂]_n, in which the lead(II ) ions have a highly distorted bicapped trigonal antiprism coordination. Lead(II ) ions are bridged by carboxyl groups of sac forming one‐dimensional linear chains, running parallel to the a axis. The intrachain Pb···Pb distances are 4.4490(3) and 4.4679(3)Å. The individual chains are connected by N—H···O_sulfonyl and C_ampy—H···O_sulfonyl type hydrogen bonds, resulting in a three‐dimensional network. The sac ligand acts as bidentate and bridging ligand, while ampy behaves as an N, N′ donor. The IR spectra of the lead(II ) complex are discussed in detail.     

Bis(Saccharinato)Nickel(II) Complexes with 2-Aminomethyl and -Ethylpyridines. Syntheses,Crystal Structures,Spectral and Thermal Analyses of trans-[Ni(sac-N)2(ampy-N,N′)2] and trans-[Ni(sac-O)2(aepy-N,N′)2]

The trans-bis(saccharinato)nickel(II) complexes with 2-aminomethylpyridine (ampy) and 2-aminoethylpyridine (aepy) have been prepared and characterized by elemental analyses, i.r., u.v.–vis., magnetic measurements and single crystal X-ray diffraction. Both structures consist of discrete molecules of the title complexes, in which the nickel(II) ion lies on an inversion centre and is octahedrally coordinated by two bidentate (N,N) ampy or aepy ligands and two anionic sac ligands, occupying trans positions. The most interesting feature of the complexes is the coordination of sac. In [Ni(sac)₂(ampy)₂], sac is N-bonded, whereas it is O-coordinated in [Ni(sac)₂(aepy)₂]. The i.r. spectra and thermal behaviour of both complexes are discussed in detail.     

Synthesis,electrochemistry, and <Emphasis Type="BoldItalic">in situ</Emphasis> spectroelectrochemistry of a new water-soluble zinc phthalocyanine substituted with naphthoxy-4-sulfonic acid sodium salt

A new water-soluble zinc phthalocyanine, 2,9,16,23-tetrakis[4-(1-naphthoxy-4-sulfonic acid sodium salt)] phthalocyaninato zinc NhtZnPc, where Nht indicates the naphthoxy-4-sulfonic acid sodium salt, was synthesized and its electrochemical and spectroelectrochemical properties were investigated in DMSO solution. The formation of NhtZnPc was monitored with the UV–vis spectral changes of NhtH₂Pc in MeOH solution. The electrochemical studies showed that NhtZnPc displayed two reduction waves assigned to Pc(3−)/Pc(2−) and Pc(4−)/Pc(3−) couples, while it also showed one oxidation wave which was assigned to Pc(−)/Pc(2−) couples. The half-wave potential of the first reduction is shifted by 0.067 V compared to that of unsubstituted metal-free phthalocyanine (H₂Pc). This result shows that the weak electron-withdrawing sulfonated-naphthoxy groups on macrocyle core make the reduction processes of NhtZnPc easier in DMSO solution. The spectroelectrochemical results showed that the first reduction product exhibited the characteristic spectral changes corresponding to mono-anionic species of zinc phthalocyanine having long-term stability during the reduction process. But, the second reduction product resulted in unstable di-anionic forms in DMSO.     

ELECTRORHEOLOGICAL PROPERTIES OF DIATOMITE/SILICONE OIL SUSPENSIONS UNDER DC FIELDS

In this study, electrorheological （ER） behavior of suspensions prepared from 3.0 and 9.0 μm diatomite particulate, dispersed in insulating silicone oil （SO） medium was investigated. Sedimentation stabilities of suspensions （c = 5 wt%） prepared using these diatomite powders were determined to be 32 days （d = 3 μm） and 24 days （d = 9 μm）, respectively. ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. Shear stress of diatomite suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions decreased sharply with increasing shear rate and particle size, showing a typical shear thinning non-Newtonian visco-elastic behavior. Effects of high temperature and polar promoter onto ER activity ofdiatomite/SO system were also investigated.