Faculty Profiles - YAJIMA Setsuko

Published Papers - YAJIMA Setsuko

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Neutral carrier-type ion sensors based on sol-gel-derived membranes incorporating a bis(crown ether) derivative by covalent bonding

K Kimura, T Sunagawa, S Yajima, S Miyake, M Yokoyama

ANALYTICAL CHEMISTRY ( AMER CHEMICAL SOC ) 70 ( 20 ) 4309 - 4313 1998.10

Sol-gel-derived membranes incorporating crown ether neutral carriers by covalent bonding have been designed for durable, nontoxic neutral carrier-type ion sensors by sol-gel processing using tetraethoxysilane, diethoxydimethylsilane, and their corresponding alkoxysilylated neutral carriers. A tetraphenylborate anion was also bound chemically to the neutral carrier-type sol-gel-derived membranes for suppressing anion interference and membrane impedance. Ion-sensitive field effect transistors (ISFETs) based on the sol-gel-derived membranes modified chemically by crown ether derivatives, such as 16-crown-5 and bis(12-crown-4) derivatives, showed high performance, high sensitivity in wide cation activity ranges, short response time, and high electrode durability. Specifically, high ion selectivities of practical use in biological systems were attained in the sodium ISFETs based on the chemically modified bis(12-crown-4), which has been successfully applied to sodium assay in blood sera.

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Co-ion interference for ion selective electrodes based on charged and neutral ionophores: A comparison

P Buhlmann, S Amemiya, S Yajima, Y Umezawa

ANALYTICAL CHEMISTRY ( AMER CHEMICAL SOC ) 70 ( 20 ) 4291 - 4303 1998.10

Interferences from co-ions, i.e., ions with a charge sign opposite to that of the measured ion, limit the upper detection limit of ion-selective electrodes (ISEs) based on electrically neutral or charged ionophores. A theoretical description based on phase boundary equilibria is used here to predict the co-ion interference (Donnan failure) of both types of ISEs quantitatively and to compare the extent of co-ion interference in these two cases. It is shown that, for practically relevant ionophore-site ratios, Donnan failure for ISEs based on electrically charged and neutral ionophore occurs at very similar co-ion concentrations if the charged and the neutral ionophores form complexes of equal stabilities and stoichiometries. With the exception of the selective complexation of the primary ion and charged ionophores, association of two or more ions such as between ionic sites and complexes has only a limited effect on co-ion interference. If relevant at all, ion pairing is predicted to affect upper detection limits more unfavorably in the case of neutral than in the case of charged ionophore-based ISEs. Experimental determination of co-ion interference for ISEs with five different charged and two electrically neutral H+ ionophores shows that co-ion interference increases as the stability of the H+ complexes increases and confirms that co-ion interferences for charged and neutral ionophore-based ISEs indeed occur to an equal extent if their H+ complexes have the same stabilities. These results corroborate the high potentiality of charged ionophore-based ISEs.

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Calix[4]arene derivative bearing pi-coordinate substituents as neutral carrier for silver ion sensors

K Kimura, K Tatsumi, S Yajima, S Miyake, H Sakamoto, M Yokoyama

CHEMISTRY LETTERS ( CHEMICAL SOC JAPAN ) ( 8 ) 833 - 834 1998.08

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Complexation of tris(beta-diketonato)lanthanoids with monodentate and bidentate Lewis bases in chloroform

Y Hasegawa, A Hirasawa, S Yajima

JOURNAL OF ALLOYS AND COMPOUNDS ( ELSEVIER SCIENCE SA ) 275 859 - 862 1998.07

The enthalpy change and the equilibrium constants for the formation of adducts of tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)lanthanoids (LnA(3)) with triphenylphosphine oxide (TPPO) and 1,10-phenanthroline (phen) in chloroform across the lanthanoid series have been determined by calorimetric titration and solvent extraction techniques. The formation constants with phen increase from the light to the middle lanthanoids, and the constants do not change from the middle to the heavy lanthanoids, while the constants of the second adducts with TPPO (LnA(3)/TPPO = 1:2) decrease with increasing atomic number, although those of the first (1:1) adducts do not change much. The enthalpy change in adduct formation with phen changes remarkably from endothermic to exothermic from light to heavy lanthanoids, while the enthalpy changes with TPPO do not vary much across the series. This suggests that, in adduct formation with phen, the match between the N-N distance in phen and the size of the lanthanoids(III), as well as dehydration from LnA(3), is a significant factor in determining the stability order of the adducts, while the degree of dehydration is significant for adduct formation with TPPO. (C) 1998 Published by Elsevier Science S.A.

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Syntheses and structures of trinuclear molybdenum cluster complexes [Mo3S4Cl4(C5H5N)(5)] and [Mo3S4Cl3(C5H5N)(6)]I

J Mizutani, S Yajima, H Imoto, T Saito

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN ( CHEMICAL SOC JAPAN ) 71 ( 3 ) 631 - 636 1998.03

A trinuclear molybdenum chloro sulfide cluster complex [Mo3S4Cl4(C5H5N)(5)] (1) was synthesized by the excision of a nonmolecular cluster compound Mo3S7Cl4 with triphenylphosphine and pyridine. Three molybdenum atoms and four sulfur atoms form an incomplete cubane-type cluster core, which is coordinated by four chloro and five pyridine ligands. By the reaction of 1 with I-2 in pyridine, [Mo3S4Cl3(C5H5N)(6)]I (2) was synthesized. Three mu-S in the cluster cation and the iodine anion have short contacts, within the sum of the van der Waals radii of sulfur and iodine.

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Donnan exclusion failure of neutral ionophore-based ion-selective electrodes studied by optical second-harmonic generation

S Yajima, K Tohda, P Buhlmann, Y Umezawa

ANALYTICAL CHEMISTRY ( AMER CHEMICAL SOC ) 69 ( 10 ) 1919 - 1924 1997.05

Optical second harmonic generation (SHG) at the liquid-liquid interfaces of ionophore-free and neutral ionophore-incorporated membranes has been measured in the presence and absence of ionic sites in order to better understand the influence of ionic sites on the potentiometric responses of liquid membrane ion-selective electrodes. Quick and lasting EMF and SHG responses were observed upon increasing the primary ion activity in aqueous solutions in contact with membranes with ionic sites. For membranes without ionic sites, transient EMF responses due to extraction of primary ion salts occurred. They were accompanied by very similar transient changes in the SHG intensity. No EMF and SHG responses to the primary ion activity were, however, observed for site-free membranes in equilibrium with the aqueous phase, The extent of charge separation at the interfaces of such membranes, as observed by SHG from primary ions or primary ion complexes, does not depend on the primary ion activity in the aqueous phase. This explains why membranes free of ionic sites do not exhibit EMF responses and confirms that ionic sites are a necessity for counterion-independent primary ion responses of potentiometric sensors based on neutral carriers.

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Ion-transfer polarographic study of the distribution of alkali and alkaline-earth metal complexes with 3m-crown-m ether derivatives (m=6,8) between water and nitrobenzene phases

Y Kudo, T Miyakawa, Y Takeda, H Matsuda, S Yajima

JOURNAL OF INCLUSION PHENOMENA AND MOLECULAR RECOGNITION IN CHEMISTRY ( KLUWER ACADEMIC PUBL ) 26 ( 4 ) 331 - 341 1996

Stability constants (beta(1)(NB)) of the 1 : 1 cationic complexes of Li+, Na+, K+, Ca2+, Sr2+ and Ba2+ with benzo-18-crown-6 (B18C6), Ca2+ and Sr2+ with 18C6 and dibenzo-18C6 and Li+, Na+, Ca2+, Sr2+ and Ba2+ with dibenzo-24-crown-8 in a nitrobenzene (NB) solution saturated with water (w) were determined at 25 degrees C by ion-transfer polarography. From these values, distribution constants (K-D,K-ML) Of the 18C6-derivative complex cations between the w- and NB-phases were evaluated using the thermodynamic relation: K-D,K-ML = K beta(1)(NB) where K (mol dm(-3)) is an overall equilibrium constant of the processes related to the complexation in the w-phase. The data on the distribution of the 18C6-derivative complex cations between the two phases and the complexation in the NB-phase were examined on the basis of an increase in the number of water molecules hydrated to the species relevant to these processes. The 18C6 derivatives showed higher solubilities in the NB-phase than in the w-phase by complexing with the univalent-metal ions, while, for the divalent-metal ions, the derivatives showed lower solubilities in the NB-phase.

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EMF RESPONSE OF NEUTRAL-CARRIER BASED ION-SENSITIVE FIELD-EFFECT TRANSISTORS WITH MEMBRANES FREE OF IONIC SITES

P BUHLMANN, S YAJIMA, K TOHDA, Y UMEZAWA

ELECTROCHIMICA ACTA ( PERGAMON-ELSEVIER SCIENCE LTD ) 40 ( 18 ) 3021 - 3027 1995.12

Response characteristics of field effect transistors covered by membranes containing neutral carriers and an organic liquid but neither a polymer nor ionic sites were determined. The commercially available 2-nitrophenyl octyl ether and dioctyl sebacate, both frequently used plasticizers for poly(vinyl chloride) ISE membranes, had impurity concentrations large enough to lead to small emf responses. Upon removal of these impurities by HPLC, no emf responses were detectable any more, which seems to be due to a negligibly small permselective uptake of primary ions into the membrane and not the high impedance of the membrane bulk. The use of membranes of the more polar nitrobenzene and 2-fluoro-2'-nitrodiphenyl ether resulted in small but transient emf responses. The absence of ionic sites led however to the failure of permselectivity and resulted in co-extraction even of the highly hydrophilic chloride ions. Liquid membranes containing neutral carriers but no ionic sites are thus not only unsuitable for ISEs due to their high impedance, but also because it is very likely that either the failure of permselectivity occurs or the concentration of primary ions permselectivity entering the membrane is too small to determine the phase boundary potential.

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STABILITIES IN WATER OF 1/1 LARIAT 16-CROWN-5 COMPLEXES WITH METAL-IONS - TRANSFER ACTIVITY-COEFFICIENTS FROM PROTIC TO APROTIC-SOLVENTS OF 1/1 COMPLEXES OF LARIAT AND SUBSTITUTED 16-CROWN-5 DERIVATIVES WITH METAL-IONS

Y TAKEDA, T KIMURA, S OCHIAI, S YAJIMA, Y KUDO, M OUCHI, T HAKUSHI

JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS ( ROYAL SOC CHEMISTRY ) 91 ( 22 ) 4079 - 4082 1995.11

Stability constants (K-ML) of 1:1 complexes of 15-(2,5-dioxahexyl)-15-methyl-16-crown-5 (L16C5) with metal ions have been determined in water at 25 degrees C by conductometry and potentiometry with ion-selective electrodes. The selectivity order of L16C5 to monovalent and bivalent metal ions are Ag+ > Na+ > Tl+ > K+ and Sr2+ > Ba2+ > Pb2+, respectively. The selectivity is not altered by the side chains. The stability of the L16C5-metal ion complex in water is much lower than might be expected on the basis of the solvation power of water for the metal ion (i.e. the relative solubility of the metal ion). Transfer activity coefficients (gamma) of L16C5-Na+ and -K+ complexes from water to acetonitrile, propylene carbonate and methanol [(s) gamma(H2O)(ML(+))] were calculated from the (s) gamma(H2O)(L16C5) and K-ML values determined in this study and the literature values; s, M(+) and L denote a solvent, a monovalent metal ion, and a crown ether, respectively. (s) gamma(H2O)(ML(+)) of L16C5 is larger than (s) gamma(H2O)(L16C5) and the corresponding (s) gamma(H2O)(M(+)) values. The unexpectedly low stabilities of the L16C5-Na+ and -K+ complexes in water are due to strong hydrogen bonding between the uncomplexed L16C5 and water.

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STUDIES ON THE PHASE BOUNDARIES AND THE SIGNIFICANCE OF IONIC SITES OF LIQUID MEMBRANE ION-SELECTIVE ELECTRODES

P BUHLMANN, S YAJIMA, K TOHDA, K UMEZAWA, S NISHIZAWA, Y UMEZAWA

ELECTROANALYSIS ( VCH PUBLISHERS INC ) 7 ( 9 ) 811 - 816 1995.09

Attenuated total reflectance infrared spectroscopy (ATR-IR) has been used to study the cation permselectivity of liquid-membrane ion-selective electrodes (ISEs). All spectroscopic evidence was found to agree with the interpretation of permselectivity as being due to complete exclusion of counter-ions from the boundary phase. Compared to ATR-IR, optical second harmonic generation (SHG) has an even more pronounced surface sensitivity. It has been demonstrated to be a promising new technique for the study of ISE response mechanisms, as it allows one to observe the actual phase boundary. On the other hand, further potentiometric evidence for the influence of ionic sites on the emf response was found, both by a study of membranes free of ionic sites as well as by the investigation of leaching processes at poly(vinyl chloride) membranes. Finally, the use of a photoresponsive crown ether ionophore allowed the determination of emf response characteristics in relation to the ionophore concentration without any changes in the membrane composition.

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SYNTHESIS OF AN EQUILATERAL TRIANGULAR MOLYBDENUM CLUSTER COMPLEX [MO3(MU-3-S)2(MU-S)3(PME3)6] WITH 8 CLUSTER VALENCE-ELECTRONS

K TSUGE, S YAJIMA, H IMOTO, T SAITO

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY ( AMER CHEMICAL SOC ) 114 ( 20 ) 7910 - 7912 1992.09

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