1,3‐Alternate Calix[4]arenecrown‐5 Conformers: New Synthetic Ionophores with Better K+/Na+ Selectivity than Valinomycin

Casnati, Alessandro; Pochini, Andrea; Ungaro, Rocco; Bocchi, Carlo; Ugozzoli, Franco; Egberink, Richard J.M.; Struijk, Helma; Lugtenberg, R.J.W.; Jong, Feike de; Reinhoudt, David N.

doi:10.1002/chem.19960020413

Cited by 169 publications

(121 citation statements)

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“…1,2 Proximally bridged calix [4]crowns have been obtained, but only in relatively low yield (<40%). 3,4 Thiacalix [4]arene is an interesting novel member of the calixarene family.…”

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confidence: 99%

Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

Leeuwen¹,

Beijleveld²,

Kooijman

et al. 2002

Tetrahedron Letters

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Abstract-Bridging of p-t-butylthiacalix[4]areneUnsubstituted thiacalix [4]arene is able to complex various transition metals, due to the presence of the bridging sulfur atoms. 7 The participation of sulfur in the complexation has been observed in X-ray crystal structures of complexes with alkali metal cations. 8 The complexation properties of thiacalix[4]arenes can be altered, both by functionalizing the lower rim with ligating sites or by oxidation of the bridging sulfur atoms. With 4 equiv. of Cs 2 CO 3 after 6 h, reaction of 1 with 2 (1.8 equiv.) exclusively afforded the 1,2-alternate thiacalix[4]biscrown-4 4 in 72% yield upon precipitation of the crude reaction mixture with methanol/acetone. Also the reaction of 1 and 3 (1.8 equiv.) with 4 equiv. of base gave a fast reaction (12 h, 100% conversion). The reaction gave a mixture of the 1,2-alternate thiacalix[4]biscrown-5 5 and the corresponding 1,3-alternate isomer 6. The pure thiacalix[4]biscrown-5 isomers 5 (27%) and 6 (15%) were isolated by fractional precipitation from methanol/acetone mixtures. Surprisingly, the proximal thiacalix[4]biscrowns-4 and -5 were only obtained in the 1,2-alternate conformation. The corresponding proximally substituted thiacalix[4]monocrown and proximally substituted cone thiacalix[4]biscrown compounds could not be detected. Compounds 4 and 5 were characterized by NMR ( 1 H and 13 C) and MS. 20,21 Definite proof for the 1,2-alternate thiacalix[4]biscrown-5 5 was obtained by an X-ray crystal structure (Fig. 1).22

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“…1,2 Proximally bridged calix [4]crowns have been obtained, but only in relatively low yield (<40%). 3,4 Thiacalix [4]arene is an interesting novel member of the calixarene family.…”

mentioning

confidence: 99%

Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

Leeuwen¹,

Beijleveld²,

Kooijman

et al. 2002

Tetrahedron Letters

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“…cations would be the thiacalix [4]arene-crowns. 16 A number of thiacalix [4]arene-crowns have already been reported by several groups, namely, 1,3-alternate thiacalix [4]arene-biscrowns, 17 bridged thiacalix [4]arene-monocrowns.…”

Section: Journal Of the Korean Chemical Societymentioning

confidence: 99%

“…Calix [4]arene-crowns are highly selective ionophores for potassium and cesium cations. [1][2][3][4] In particular the 1,3-dimethyl ether of p-tert-butylcalix [4] crown-5-ether (1) has shown a surprisingly high K + /Na + selectivity in extraction.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] In particular the 1,3-dimethyl ether of p-tert-butylcalix [4] crown-5-ether (1) has shown a surprisingly high K + /Na + selectivity in extraction. 5 Thiacalix [4]arenes in the presence of sulfur atoms instead of methylene groups exhibit novel structural and functional features including easy oxidation of sulfur bridges and extra binding sites, which make these compounds very interesting with potential applications such as inclusion of a variety of guest molecules, recognition of metal ions, chiral recognition, novel anion receptors, and novel dendriticshelled molecular receptors. [6][7][8][9][10][11][12][13][14][15] Therefore, one of the obvious classes of ionophores suitable for selective complexation of alkali metal 522 김광호 ․ 최종인…”

Section: Introductionmentioning

confidence: 99%

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mPW1PW91 Calculated Relative Stabilities and Structures for the Conformers of 1,3-dimethoxy-p-tert-butylthiacalix[4]crown-5-ether

2009

Journal of the Korean Chemical Society

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ABSTRACT. Molecular structures of the various conformers for the 1,3-dimethoxy-p-tert-butylthiacalix[4] crown-5-ether (3) were optimized by using DFT B3LYP/6 -31 + G(d,p) and mPW1PW91/6 -31 + G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the energy differences and structures of eight in/out orientations (cone_oo, cone_oi, pc_oo, pc_io, pc_oi, pc_ii, 13a_oo, 13a_io) of two methoxy groups in three major conformations (cone, partial-cone and 1,3-alternate). The 13a_oo (out-out orientation of the 1,3-alternate conformer) is calculated to be the most stable among eight different conformations of 3, and in accord with the experimental result. The ordering of relative stability resulted from the mPW1PW91/6 -31 + G(d,p) calculation method is following: 13a_oo > 13a_io∼pc_io∼cone_oo > cone_oi∼pc_oo∼pc_oi > pc_ii.

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“…4 In addition to valinomycin, several other ionophores have been used in the preparation of potassium ISEs. [5][6][7][8] Among these, bis(crown ethers) with two 15-crown-5 ethers attached via a bridge [7][8][9][10] exhibit a favorable potassium binding over sodium due to the formation of sandwich-type complexes with potassium. 9,10 The observed selectivities of ISEs prepared with bis(15-crown-5 ethers) are sometimes comparable to those obtained by using valinomycin as the ionophore.…”

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confidence: 99%

Synthesis and Evaluation of a Bis(crown ether) Ionophore with a Conformationally Constrained Bridge in Ion-Selective Electrodes

et al. 1998

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There has been a recent rapid growth in the development of chemical sensors because of the demand for simple analytical techniques that can provide continuous monitoring of analytes in a variety of matrices. [1][2][3] In the area of membrane-based ion-selective electrodes (ISEs), special emphasis has been placed on the composition of the membrane phase and on the development of new ionophores, aiming at enhancing the potentiometric response characteristics (e.g., selectivity, sensitivity, linear range and lifetime) of the ISEs.The majority of cation-selective electrodes are based on neutral carrier ionophores. In particular, the antibiotic valinomycin has proved to be an excellent ionophore in potassium-selective liquid-polymeric membrane electrodes. 4 In addition to valinomycin, several other ionophores have been used in the preparation of potassium ISEs. 5-8 Among these, bis(crown ethers) with two 15-crown-5 ethers attached via a bridge [7][8][9][10] exhibit a favorable potassium binding over sodium due to the formation of sandwich-type complexes with potassium.9,10 The observed selectivities of ISEs prepared with bis(15-crown-5 ethers) are sometimes comparable to those obtained by using valinomycin as the ionophore. 5Bis(crown ethers) can be prepared with functional groups that allow their covalent attachment on polymer matrices. This is an advantage when designing ISEs with extended lifetimes because covalent attachment of the ionophore precludes its leaching from the polymer membrane phase to the aqueous phase. 11-13 Direct attachment of a bis(crown ether) to a polymer backbone, however, may restrict the free movement of the ionophore or pose serious steric problems with the backbone of the polymer, which could lead to worsening of the response.7,14 A long flexible chain connecting the bis(crown ether) and the polymer could provide a solution to this problem. In this paper, we report on the synthesis and evaluation of a new bis(crown ether) (BCE) ionophore with a long and flexible side chain, which can serve as a precursor for the chemical immobilization to a polymer backbone. Another feature of the designed ionophore is the incorporation of a conformationally constrained bridge (an isophthalic acid derivative) between the two crown ether moieties. This isophthalic acid derivative allows each of the crown ether macrocycles to be in a parallel alignment with each other during complexation, which helps maximize their interaction with the analyte ion. ExperimentalReagents 5-Nitroisophthalic acid, 4-nitrobenzo-15-crown-5, 10% Pd/C, 97% thionyl chloride, triethylamine, aluminum oxide (neutral, Brockmann I), and stearoyl chloride were all obtained from Aldrich (Milwaukee, WI). Selectophore-grade tetrahydrofuran (THF), 2-nitrophenyloctyl ether (NPOE), tris(2-ethylhexyl)phosphate (TOP), bis(2-ethylhexyl) sebacate (DOS), bis(1- A new bis(crown ether) ionophore containing two benzo-15-crown-5 moieties connected with each other via a conformationally constrained bridge attached to a C18-lipophilic side chain was desig...

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1,3‐Alternate Calix[4]arenecrown‐5 Conformers: New Synthetic Ionophores with Better K⁺/Na⁺ Selectivity than Valinomycin

Abstract: subsequent dialkylation with NaH/DMF and KOtBuITHF, respectively. In the solid state (X-ray), compound 6 a adopts a flattened cone conformation, which is also found to be most abundant in CD,CN and CD,OD solution. Upon complexation with potassium picrate compound 6a was converted quantita-

Cited by 169 publications

References 50 publications

Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

mPW1PW91 Calculated Relative Stabilities and Structures for the Conformers of 1,3-dimethoxy-p-tert-butylthiacalix[4]crown-5-ether

Synthesis and Evaluation of a Bis(crown ether) Ionophore with a Conformationally Constrained Bridge in Ion-Selective Electrodes

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