Chemical sensing based on membrane potential change induced by host-guest complexation at a membrane surface¹

Abstract

1994) Chemical sensing based on membrane potential change induced by host-guest complexation at a membrane surface 1 , Supramolecular Chemistry, 4:2, 101-113,Three new principles for discrimination of organic guests by the membrane potential change are described, which are based on the host-guest recognition of charged groups, hydrogen bonding groups, or steric shapes of nonpolar moieties. (i) Potentiometric discrimination by the recognition of charged groups has been attained by liquid membrane type electrodes containing lipophilic macrocyclic polyamines as the sensory elements. These electrodes displayed potentiometric selectivities for organic anions according to the amount or proximity of negative charges. Thus, the strongest responses were observed for such guests as ATP4-having a large number of negative charges as well as maleatez-and phthalatezhaving negative charges at the closest distance within the molecule.(ii) Potentiometric discrimination by the recognition of hydrogen bonding groups has been attained by an electrode containing a lipophilic cytosine-pendant triamine, which functions as a ditopic receptor for guanine nucleotides by an electrostatic interaction with the phosphate group and a complementary base pairing with the guanine base. This electrode displayed nearly all-or-nothing selectivities between guanine and adenine nucleotides. Selective ref Hokkaido University. Hiroshima University.sponses to guanine nucleotides were also obtained by double receptor type electrodes containing a macrocyclic tetraamine and a neutral cytosine derivative despite the fact that both of these hosts, when existed separately, showed only weak responses to these guests. (iii) Potentiometric discrimination by the recognition of steric shapes of nonpolar moieties has been attained by an electrode containing a lipophilic hexaester of calix[6]arene having an inclusion cavity for organic guests. At pH 7.0, the strongest responses were obtained for primary amine guests such as 2-phenylethylamine and 1-octylamine having no bulky substituent at the a-carbon that could sterically hinder the formation of tripodal hydrogen bonds between the NH,+ group of the guest and the ester carbonyl groups of the host. A comparison of potentiometric selectivities with those of the electrode containing dibenzo-18-crownd, as well as 'H-NMR results on the geometry of the host-guest complex, strongly supported a potentiometric shape discrimination effect based on the inclusion of guests within the calix[6]arene cavity having a well-defined structure.

Optimum Concentration of Anionic Sites in Lipophilic Macrocyclic Pentaamine-Based Liquid Membranes for Potentiometric Responses to Anionic Analytes

“…This result explains why PVC liquid membranes based on macrocyclic pentaamine show strong responses to anionic analytes without added anionic sites. [14][15][16] The site concentration dependence of the EMF responses calculated from the diffuse double layer-based model was well fitted to the observed one with the same stability constant of the protonated pentaamine-anionic analyte complex for membranes with various concentrations of anionic sites. This result allows us to explain the influence of the anionic site concentrations on the EMF response of macrocyclic pentaamine-based membranes as follows.…”

“…Poly(vinyl chloride) (PVC), bis(2-ethyl-hexyl)phthalate (DOP), maleic acid, phosphate disodium salt, ortho phosphoric acid, tetrahydrofuran (THF) and potassium tetrakis(pchlorophenyl)borate (KTClPB) were purchased from Wako Pure Chemicals (Osaka, Japan). A lipophilic derivative of macrocyclic pentaamine (C16H33- [16]aneN5) [1] was synthesized according to a previously reported procedure. [16][17][18] Membrane preparation and EMF measurements Solvent polymeric membranes containing 1.5 wt% lipophilic macrocyclic pentaamine [1], 73.5 wt% plasticizer (DOP), 25 wt% PVC and anionic salt (KTpClPB) at the concentration versus to ionophore: 1 mol%, 10 mol% and 100 mol%, were prepared as follows: A homogeneous solution of lipophilic macrocyclic pentaamine, KTpClPB, DOP and PVC in THF (distilled from KOH prior to use) was poured into a glass ring (0.8-cm diameter) standing on a glass plate; the solvent was allowed to evaporate for 48 h. The thus-prepared membrane was mounted on a glass tube by Teflon tape.…”

“…11,12 Macrocyclic pentaamines 13 have been applied as a sensory element for ISEs to discriminate organic anions. [14][15][16] This type of ionophore is known to acquire a strong anion receptor function by multiple protonation in acidic to neutral aqueous solutions. 13 In liquid membranes, this ionophore, neutral itself, gains its active charged form upon protonation at the membrane surface, and consequently recognizes analyte anions in the sample solution.…”

Potentiometric response and mechanism of anionic recognition of heterocalixarene-based ion selective electrodes

“…Support for this latter hypothesis comes from proton binding studies of a pyridine-strapped 5,12-dioxocyclam-based macrocycle [47]. Meyer et al showed that this elaborated pyridinecontaining receptor behaves as a diprotic base with pK B1 =8.94(1) and pK B2 =2.32 (9). However, in this latter instance the diprotonated species was thought to be stabilized by additional intramolecular hydrogen bonding within the cavity.…”

“…ISEs are also of obvious interest because they can help translate the chemistry of new substrate binding systems into tools that can be used to recognize selectively various targeted species in the presence of potentially interfering analytes. In the specific case of anion recognition, this approach has been explored extensively by Umezawa, Meyerhoff, Simon, Reinhoudt, Schmidtchen and others using a range of receptors including bis-guanidinium [1][2], porphyrins [3], protonated polyamines [4][5][6][7], and protonated sapphyrins [8][9][10], as well as a variety of Lewis acidic systems such as calixarenes [11][12][13][14][15], uranylsalenophenes [16][17], metalloporphyrins [18][19][20][21][22], metallocenes [23], other organometallic derivatives [24][25][26], and fluorinated compounds [27].…”