Kayoko Umezawa

Potentiometric selectivity coefficients of ion-selective electrodes. Part II. Inorganic anions (IUPAC Technical Report)

Potentiometric selectivity coefficients, KA,Bpot have been collected for ionophore-based ion-selective electrodes (ISEs) for inorganic anions reported during 1988-1998. In addition to the actual numerical values of KA,Bpot together with the methods and conditions for their determination, response slopes, linear concentration (activity) ranges, chemical compositions, and ionophore structures for the ISE membranes are tabulated.

Cation permselectivity in the phase boundary of ionophore-incorporated solvent polymeric membranes as studied by Fourier transform infrared attenuated total reflection spectrometry

Abstract The behaviour of permselective membrane transport was studied by Fourier transform IR attenuated total refelction spectrometry and potential measurements for the solvent polymeric membranes incorporating several different ionophores. The stoichiometric ratios between the complexed cations and their corresponding counter anions in the phase boundary, 0.31–1.8 υm in depth, of the membrane were determined for each membrane made in contact with various primary ion solutions. When hydrophilic counter anions were used for the primary ion solutions, the IR spectra of the membrane were exclusively those of the complexed cations, and no IR-active anionic peak appeared. The intensity of the former peaks was found to be dependent on an added anionic site, carboxylated poly(vinyl chloride) and a derivative of tetraphenylborate, in the membranes, and also on the penetration depths of the IR beams used. In contrast, when a hydrophobic counter anion SCN − , was used for the primary ion solutions, the spectra from both the complexed cation and corresponding counter anion were seen, of which the stoichiometric ratios changed depending on the concetrations of primary ion salts, and on the coexistence of a derivative of tetraphenylborate in the membrane. The results are discussed in terms of the extent of cation permselectivity and its relevance to the potential of ionophore-incorporated liquid membrane ion-selective electrodes.

Expanded porphyrin incorporated solvent polymeric membrane electrodes: protonation and interaction with an analyte anion at organic/water interface as studied by optical second harmonic generation and Fourier transform infrared attenuated total reflectance spectrometry

Abstract Optical second harmonic generation (SHG) at the surfaces of poly(vinyl chloride) (PVC) supported liquid membranes based on expanded porphyrins was measured to better understand the relationship between protonation of ionophores at the membrane surface and selective EMF responses by the membranes toward anionic analytes in low pH ranges. Sapphyrin and rubyrin were chosen as representative examples of the ionophores and 3,5-dinitrobenzoate as their primary analyte anion. The square root of SHG intensity I 2ω , of the sapphyrin based membranes increased in sigmoidal two steps according to the decrease in pH in the adjacent aqueous phase in the absence of 3,5-dinitrobenzoate. This result was attributed to the change of protonation form of sapphyrin, i.e. unprotonated-sapphyrin, monoprotonated-sapphyrin and diprotonated-sapphyrin, respectively, apparent surface protonation constants (apparent surface pKa1, pKa2) for sapphyrin at the water/membrane interface were determined therefrom. Apparent surface pKa1 thus estimated for sapphyrin was found to be close to the pHs at which the corresponding membrane begun to exhibit EMF and SHG responses toward 3,5-dinitrobenzoate. Fourier transform infrared attenuated total reflectance (FTIR-ATR) measurements of the sapphyrin incorporated membrane showed that 3,5-dinitrobenzoate was transported into the membrane phase only in the pH range where sapphyrin is highly protonated at the water/membrane interface and formed a complex with protonated sapphyrin. From these SHG, FTIR-ATR and EMF results, it is concluded that the high degree of protonation of sapphyrin at the membrane surface is requisite for the generation of anionic EMF responses toward the primary analyte anion. Apparent surface pKa1 values estimated for sapphyrin in the sapphyrin and KTpClPB based membrane and for rubyrin in the rubyrin based membrane were also found to match the pHs below which the corresponding membranes exhibit EMF responses toward 3,5-dinitrobenzoate.

New chromotropic behavior of manganese complexes with 1,4,7-triazacyclononane-N,N′,N″-tricarboxylates

Abstract Synthesis and characterization of a manganese(III) complex containing 1,4,7-triazacyclononane-N,N′,N″-tripropionate (tacntp) are reported. The complex [Mn(acntp)](II) (1) crystallizes in a hexagonal environment of a facial N3O3 donor set with space group P3c1, apparently violating the Jahn–Teller effect. Complex 1 is more stable for reduction than the corresponding complex [Mn(tacnta)] (2) where, tacnta is a triacetate homologue of tacntp. Both complexes showed reversible electrochromism in aqueous solutions. In addition, complex 1 was reversibly reduced in a methanol solution too. They also showed solvatochromism in a variety of solvents. The UV–Vis absorption maxima of the complexes were correlated to the acceptor number of the solvent.

Synthesis and structural studies of diamagnetic first-row transition metal complexes with the rigid nitrogen ligand: bis[N-(2,6-diisopropylphenyl)imino]acenaphthene

Abstract Reported are the syntheses and characterization of diamagnetic copper(I) and iron(II) complexes with the bidentate nitrogen ligand bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (o,o′-iPr2C6H3-BIAN). Namely, they are [Cu(o,o′-iPr2C6H3-BIAN)2](ClO4)(AcOH) (1), and [Fe(bipy)2(o,o′-iPr2C6H3-BIAN)](ClO4)2 (2), where bipy=2,2′-bipyridine, AcOH=acetic acid. Moreover, the crystal structure of the novel dimeric Cu(I) compound with the p-brominated derivative of the o,o′-iPr2C6H3-BIAN ligand, is also discussed. In [CuBr(o,o′-iPr2-p-BrC6H2-BIAN)]2 (3), the respective Cu(I) ion is in four-coordinate environment tetrahedrally surrounded by two imine nitrogen atoms of o,o′-iPr2-p-BrC6H2-BIAN, and by two bridging bromide atoms.

Liquid membrane electrodes for nucleotides based on sapphyrin, cytosine-pendant triamine and neutral cytosine derivative as sensory elements

A number of anion-selective lectrodes have been developed by the use of alkyhin compounds, vitamin B,, and metalloporphyrin derivatives, diphosphonium and bis(quaternary ammonium) salts, and macrocyclic polyamines. Of these, the macrocyclic polyamiue electrodes are characteristic in that the host molecule functions as an anion receptor by multiprotonation at the membrane surface [l-3], and as a remarkable feature, have the ability to diiriminate among the adenine nucleotides according to the difference in the number of negative charges. However, since protonated macrocyclic polyamines appear to bind mainly to the phosphate group of nucleotides, it would be difficult to effect discrimination among similarly charged nucleotides bearing different kinds of bases. On the other hand, some new types of receptors for nucleotides, e.g., cytosiue derivatives [4] and Kemp’s acid derivatives [S], have been developed. These exploit several types of recognition sites, namely: (1) a basepairing site for nucleic bases such as cytosine and imide moieties; (2) a rr-rr stacking site for nucleic bases such as naphthalene and acridine moieties; and (3) an electrostatic binding site for phosphate groups such as protonated amine and guanidiniutn moieties. In this paper, we wish to report potentiometric response properties for nucleotides displayed by four

Ftir-Atr and Solvent Extraction Studies on Potentiometric Responses of Neutral Carrier Type Liquid Membranes

Permselective ion transport at the surface of poly(vinyl chloride) supported neutral carrier liquid membranes, contacted with solutions of different kinds of metal salts was investigated by FTIR-ATR spectroscopy. When the PVC supported membranes containing dibenzo-18-crown-6 and bis[(benzo-15-crown-5)-4′-methyl] pimelate respectively were contacted with KCl aqueous solution, selective transport of K+ ions into the interfacial region of the membrane was evidenced by the change in IR spectra through complexation of K+ ions with neutral carriers. The cation permselectivity was correlated with almost zero extractability of liquid/liquid extraction of the corresponding bulk solvent extraction systems. A general empirical relation between potentiometric response slopes of liquid membranes and extractability of metal salts in a series of bulk extraction systems was also deduced.