Co-reporter:Yanfei Yang, Eun Kyung Lee, Kazimierz Surowiec, Richard A. Bartsch
Tetrahedron 2015 Volume 71(Issue 1) pp:77-84
Publication Date(Web):7 January 2015
DOI:10.1016/j.tet.2014.11.042
Several new di-ionizable p-tert-butylcalix[4]arene-1,2-crown-5 compounds were prepared in the cone conformation. For comparison with reported ligands, the systematic structural variation was a change of the pendent acidic groups from two adjacent –OCH2CO2H or –OCH2C(O)NHSO2Z (with Z=–Me, –Ph, –C6H4–4-NO2, –CF3) units to two adjacent –O(CH2)4CO2H or –O(CH2)4C(O)NHSO2Z groups. Competitive solvent extractions of alkaline earth metal (AEMC) cations from aqueous solutions into chloroform by these ligands were performed. Also single species solvent extractions were conducted for the divalent heavy metal cations of Pb2+ and Hg2+. Comparison of the extraction data for the new ligands with those reported reveal that the ligands with shorter proton-ionizable side arms are more effective divalent metal ion extractants.
Co-reporter:Yanfei Yang;Eun Kyung Lee
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2015 Volume 81( Issue 3-4) pp:367-376
Publication Date(Web):2015 April
DOI:10.1007/s10847-014-0463-x
Di-ionizable calix[4]arene-1,3-crown-4 ligands with an enlarged crown ring were synthesized for comparison as metal ion extractants with analogues having identical pendent acidic groups, but a “normal” crown ring. The ligand conformation and regioselectivity are verified by NMR spectroscopy. Competitive solvent extraction of hard alkali metal cations and alkaline earth metal cations from aqueous solutions into chloroform by these new ligands were performed. Single species solvent extractions were conducted with intermediate Pb2+ and soft Hg2+. Comparison of the results with those from di-ionizable calix[4]arene-1,3-crown-4 ligands having “normal” crown rings provides insight into the effects of enlarging the crown ring as a function of the metal ion species being extracted and the identity of the pendent ionizable groups. Enlargement of the crown ring produced the largest increase in extraction efficiency with soft Hg2+.
Co-reporter:Dong Eun Kang;Jennifer D. Crawford
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2015 Volume 83( Issue 1-2) pp:37-43
Publication Date(Web):2015 October
DOI:10.1007/s10847-015-0536-5
Cone calix[4]arene-1,3-crown-7 ligands bearing acidity tunable di-ionizable groups were prepared to examine the effect of the cavity size for the crown ether ring. The results of solvent extraction from aqueous solutions into chloroform show that these ligands are highly selective for Ba2+ among the alkaline earth metal cations and are good extractants for Pb2+ and for Hg2+.
Co-reporter:Pillhun Son;Gaurav Arora
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2015 Volume 81( Issue 3-4) pp:451-464
Publication Date(Web):2015 April
DOI:10.1007/s10847-015-0474-2
Four new series of 5,17-(di-ionizable)-25,26,26,28-tetraalkoxycalix[4]arene ligands are prepared. The ionizable groups are carboxylic acid and N-(Z)sulfonyl formamide functions with Z = –Me, –Ph, –C6H4–4-NO2, and –CF3. When the four alkoxy groups are methoxy, the ligand conformation is flexible. With four butoxy groups, the ligands are locked in cone, partial-cone, or 1,3-alternate conformations. Complexation abilities of the new ligands are evaluated in solvent extractions of selected divalent metal ions from aqueous solutions into chloroform. Both the conformation of the calix[4]arene unit and identity of the acidic group are found to influence the divalent metal ion extraction selectivity and efficiency.
Co-reporter:Dong Eun Kang;Eun Kyung Lee
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2015 Volume 83( Issue 3-4) pp:335-342
Publication Date(Web):2015 December
DOI:10.1007/s10847-015-0568-x
Proton di-ionizable calix[4]arene-1,2-crown-5 ligands with elongated pendant side arms are synthesized in the partial-cone conformation. Solvent extraction studies probed the influence of elongated side arms and conformation toward various metal cations. Results of the solvent extraction experiments show that these compounds are poor extractants from aqueous solutions into chloroform for hard alkali metal cations and alkaline earth metal cations and intermediate Pb2+. For soft Hg2+, the ligands with N-(X)sulfonyl carbamoyl ionizable groups exhibit very good to excellent extraction efficiency. In general, the metal ion extraction behavior for the new partial-cone conformers is quite similar to that reported recently for their cone conformational isomers.
Co-reporter:Jing Wang;Dongmei Zhang;Richard A. Bartsch
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2015 Volume 83( Issue 3-4) pp:251-256
Publication Date(Web):2015 December
DOI:10.1007/s10847-015-0560-5
Binding of five alkali metal cation (AMC) species by di-ionized calix[4]arene ligands is investigated by isothermal calorimetric titration in methanol at 25.0 °C. Acidic functions attached through the phenolic oxygens to the calixarene scaffold are –OCH2CO2H and –OCH2C(O)NHS2X with X = –Me, –Ph, –C6H4–4–NO2 and –CF3. By use of strongly basicO methoxide media, di-ionized forms of the ligands are employed for titration of the AMCs. By variation of the two remaining lower-rim substituents from –OMe to –OBu, the ring conformation is changed from flexible to cone, partial-cone and 1,3-alternate. Effects of these structural variations on the binding constants for complexation of the AMCs are assessed.
Co-reporter:Amanda L. Boston;Jennifer D. Crawford
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2014 Volume 79( Issue 1-2) pp:125-132
Publication Date(Web):2014 June
DOI:10.1007/s10847-013-0333-y
Conformationally mobile, di-ionizable 1,2-dimethoxy-p-tert-butylcalix[4]arene ligands are synthesized and compared with 1,3-dimethoxyl analogues to probe the influence of regiochemistry on metal ion extraction efficiency and selectivity. Extraction of hard alkali metal and alkaline earth metal cations, intermediate Pb2+, and soft Hg2+ from aqueous solutions into chloroform are utilized to evaluate the effect of this structural variation on the ability of the ligands to complex monovalent and divalent metal ion species.
Co-reporter:Amanda L. Boston, Eun Kyung Lee, Kazimierz Surowiec, Jerzy Gega, Richard A. Bartsch
Tetrahedron 2012 68(42) pp: 8789-8794
Publication Date(Web):
DOI:10.1016/j.tet.2012.07.103
Co-reporter:Amanda L. Boston, Eun Kyung Lee, Jennifer D. Crawford, Robert E. Hanes Jr., Richard A. Bartsch
Tetrahedron 2012 68(49) pp: 10241-10251
Publication Date(Web):
DOI:10.1016/j.tet.2012.09.065
Co-reporter:Yanfei Yang, Xiaodan Cao, David W. Purkiss, John F. Cannon, Richard A. Bartsch
Tetrahedron 2012 68(10) pp: 2233-2244
Publication Date(Web):
DOI:10.1016/j.tet.2012.01.051
Co-reporter:Yanfei Yang, Gaurav Arora, Fernando A. Fernandez, Jennifer D. Crawford, Kazimierz Surowiec, Eun Kyung Lee, Richard A. Bartsch
Tetrahedron 2011 67(7) pp: 1389-1397
Publication Date(Web):
DOI:10.1016/j.tet.2010.12.006
Co-reporter:Yanfei Yang, Xiaodan Cao, Malgorzata Surowiec, Richard A. Bartsch
Tetrahedron 2010 66(2) pp: 447-454
Publication Date(Web):
DOI:10.1016/j.tet.2009.11.058
Co-reporter:Yanfei Yang;Xiaodan Cao;Kazimierz Surowiec
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2010 Volume 66( Issue 1-2) pp:163-169
Publication Date(Web):2010 February
DOI:10.1007/s10847-009-9675-x
A regioisomer of a previously reported p-tert-butylcalix[4]arene-1,3-thiacrown-5 di(carboxylic acid) is prepared in which the thiacrown ring attachment sites are moved from distal phenolic oxygens of a cone p-tert-butylcalix[4]arene scaffold to proximal phenolic oxygens. The influence of this structural variation in the di-ionizable calixcrown ligand on competitive solvent extractions of alkali metal cations and of alkaline earth metal cations and single species solvent extractions of Hg2+ and Pb2+ from aqueous solutions into chloroform is evaluated.
Co-reporter:Chunkyung Park;Sangki Chun
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2010 Volume 66( Issue 1-2) pp:95-105
Publication Date(Web):2010 February
DOI:10.1007/s10847-009-9650-6
Synthetic routes to four calix[4]arene stereoisomers with two distal methoxycarboxy groups and two distal butoxy groups are reported. Conformations of cone, partial cone (butyl up), partial cone (acid up), and 1,3-alternate were established by 1H and 13C-NMR spectroscopy. To probe the influence of ligand conformation on metal ion complexation, extractions from aqueous solutions into 1,2-dichloroethane were performed. These included competitive alkali metal cation extractions, competitive alkaline earth metal cation extractions, and single species extractions of Pb2+ and of Hg2+. Comparisons are also made with the results for a conformationally mobile analogue in which the two butoxy groups are replaced with methoxy groups.
Co-reporter:Jing Wang, Dongmei Zhang, Thomas R. Lawson, Richard A. Bartsch
Talanta 2009 Volume 78(Issue 2) pp:477-483
Publication Date(Web):30 April 2009
DOI:10.1016/j.talanta.2008.11.038
Silica gel-immobilized, di-ionizable calix[4]arenes are employed as stationary phases in ion-exchange chromatography for selected heavy metal ions. Sorption efficiencies for Pb2+ are dependent on the structure of the calix[4]arene ligand and the linker that joins the ligand to the silica gel, as well as the acidity of the sample solution. Although the resins exhibit only poor sorption of Cd2+, they are found to be scavengers for Hg2+. Competitive sorption studies are conducted with selected resins.
Co-reporter:Malgorzata Surowiec, Radu Custelcean, Kazmiriez Surowiec, Richard A. Bartsch
Tetrahedron 2009 65(37) pp: 7777-7783
Publication Date(Web):
DOI:10.1016/j.tet.2009.07.006
Co-reporter:Xiaodong Liu, Kazimierz Surowiec, Richard A. Bartsch
Tetrahedron 2009 65(31) pp: 5893-5898
Publication Date(Web):
DOI:10.1016/j.tet.2009.06.004
Co-reporter:Carmelo Sgarlata, Giuseppe Arena, Elisa Longo, Dongmei Zhang, Yangfei Yang, Richard A. Bartsch
Journal of Membrane Science 2008 Volume 323(Issue 2) pp:444-451
Publication Date(Web):15 October 2008
DOI:10.1016/j.memsci.2008.07.004
Using functionalized calix[4]arene carrier 1 in a PIM system, Hg(II) is transported with high selectivity from acidic aqueous source phase solutions of Cd(II), Hg(II) and Pb(II) with high NaNO3 concentration into aqueous receiving solutions containing EDTA. To gain insight into this transport selectivity, complexation studies of the three heavy metal perchlorate species by ligand 1 were conducted in acetonitrile. Although 1:1 complexation of the divalent heavy metal cation by 1 was observed for Cd(II), the stoichiometries were more complicated for Hg(II) and Pb(II). Selective Hg(II) transport across the PIM is attributed to both the strength and stoichiometry of the metal ion-carrier species forming at the source phase-membrane interphase and its stripping from the membrane into the receiving phase by EDTA.
Co-reporter:Hui Zhou, Dazhan Liu, Jerzy Gega, Kazimierz Surowiec, David W. Purkiss and Richard A. Bartsch
Organic & Biomolecular Chemistry 2007 vol. 5(Issue 2) pp:324-332
Publication Date(Web):24 Nov 2006
DOI:10.1039/B611570E
Two carboxylic acid or N-(X)sulfonyl carboxamide groups were incorporated into calix[4]arene-crown-6 compounds to afford di-ionizable ligands for use in divalent metal ion separations. Acidities of the N-(X)sulfonyl carboxamide groups were tuned by variation of the electron-withdrawing properties of X. Cone, partial-cone and 1,3-alternate conformations were obtained by different synthetic strategies and their structures verified by NMR spectroscopy. Competitive solvent extractions of alkaline earth metal cations from aqueous solutions into chloroform were performed and the results compared with those reported previously for di-ionizable p-tert-butylcalix[4]arene-crown-6 analogues to probe the influence of the para-substituent on the calix[4]arene scaffold on extraction selectivity and efficiency.
Co-reporter:Dongmei Zhang, Xiaodan Cao, David W. Purkiss and Richard. A. Bartsch
Organic & Biomolecular Chemistry 2007 vol. 5(Issue 8) pp:1251-1259
Publication Date(Web):19 Mar 2007
DOI:10.1039/B700072C
Novel di-ionizable p-tert-butylcalix[4]arene-1,2-crown-3 ligands in cone and 1,2-alternate conformations were prepared as potential metal ion extractants. Selective bridging of proximal hydroxyl groups of the calix[4]arene platform by a crown-3 polyether unit was achieved under Mitsunobu reaction conditions. In addition to the carboxylic acid group, the acidity tunable N-(X)sulfonyl oxyacetamide functions [OCH2C(O)NHSO2X] with X group variation from methyl to phenyl to p-nitrophenyl to trifluomethyl were used as the proton-ionizable groups. Conformations and regioselectivities of the new ligands were established by 1H and 13C NMR spectroscopy. Competitive solvent extractions of alkali metal cations and of alkaline earth metal cations from aqueous solutions into chloroform were performed, as were single species extractions of lead(II) and mercury(II).
Co-reporter:Richard A. Bartsch;N. Kent Dalley
Journal of Inclusion Phenomena and Macrocyclic Chemistry 2007 Volume 58( Issue 3-4) pp:237-240
Publication Date(Web):2007 August
DOI:10.1007/s10847-006-9148-4
Solid-state structures have been determined for 2-methoxy-1,3-xylyl-18-crown-5 (4) (monoclinic, P21/n, a = 11.361(3) Å, b = 8.352(3) Å, c = 18.627(4) Å, β = 91.05(2)°, Z = 4) and 2-methoxy-1,3-xylyl-21-crown-6 (5) (monoclinic, Pc, a = 9.996(2) Å, b = 11.321(2) Å, c = 8.642(2) Å, β = 100.095(4)o, Z = 2). In both molecules, the aromatic units are tilted with respect to the polyether ring and the methoxyl methyl hydrogens are oriented toward ether oxygen atoms of the rings. The interatomic distances, particularly the H···O distance and angles provide important information regarding the strength of the C–H···O interactions.
Co-reporter:Chuqiao Tu, Dazhan Liu, Kazimierz Surowiec, David W. Purkiss and Richard A. Bartsch
Organic & Biomolecular Chemistry 2006 vol. 4(Issue 15) pp:2938-2944
Publication Date(Web):30 Jun 2006
DOI:10.1039/B604218J
Di-ionizable p-tert-butylcalix[4]arene-1,2-crown-5 and -crown-6 ethers in the cone conformation were prepared and their conformations and regioselectivities were verified by NMR spectroscopy. The metal ion-complexing properties of these ligands were evaluated by competitive solvent extractions of alkaline earth metal cations from water into chloroform. The ligands were found to be efficient extractants with selectivity for Ba2+. The maximal loadings were 95–100% as calculated for formation of 1 : 1 ionized ligand–metal ion complexes. With the variation of proton-ionizable groups, which were oxyacetic acid moieties and N-(X)sulfonyl oxyacetamide units with X = methyl, phenyl, 4-nitrophenyl, and trifluoromethyl, “tunable” acidity was obtained.
Co-reporter:Hui Zhou, Kazimierz Surowiec, David W. Purkiss and Richard A. Bartsch
Organic & Biomolecular Chemistry 2006 vol. 4(Issue 6) pp:1104-1114
Publication Date(Web):24 Jan 2006
DOI:10.1039/B517348E
Synthetic strategies for novel, proton di-ionizable p-tert-butylcalix[4]arene-crown-5 compounds in cone, partial-cone and 1,3-alternate conformations are reported. Selective linkage of the two diametrical phenolic oxygens in p-tert-butylcalix[4]arene with tetraethylene glycol ditosylate gave 1,3-bridged p-tert-butylcalix[4]arene-crown-5. The two remaining phenolic units were alkylated using NaH and KH as the bases to give the cone and partial-cone conformers, respectively. Preparation of the 1,3-alternate conformers utilized a different sequence in which O-alkylation was followed by crown ether ring formation. Structures of these new ligands were elucidated by 1H and 13C NMR spectroscopy. These proton-ionizable ligands were tested for their solvent extraction properties toward alkaline earth metal cations. Surprising differences in their extraction behaviors are noted compared to those reported previously for di-ionizable p-tert-butylcalix[4]arenecrown-6 analogues.
Co-reporter:Sadik Elshani, Sangki Chun, Bijan Amiri-Eliasi and Richard A. Bartsch
Chemical Communications 2005 (Issue 2) pp:279-281
Publication Date(Web):24 Nov 2004
DOI:10.1039/B411417E
New lipophilic acyclic polyethers with two N-(X)sulfonyl carbamoyl groups of “tunable” acidity exhibit remarkable selectivity for Ba2+ over other alkaline earth metal ions in competitive solvent extraction and transport across polymer inclusion membranes.
Co-reporter:Hui Zhou, Kazimierz Surowiec, David W. Purkiss and Richard A. Bartsch
Organic & Biomolecular Chemistry 2005 vol. 3(Issue 9) pp:1676-1684
Publication Date(Web):24 Mar 2005
DOI:10.1039/B501822F
Novel proton di-ionizable p-tert-butylcalix[4]arene-crown-6 compounds in cone, partial-cone and 1,3-alternate conformations are synthesized to compare the efficiency and selectivity with which they extract alkaline earth metal ions. In these ligands, a crown-6 polyether unit links alternate aromatic rings of the calix[4]arene framework. To the remaining lower-rim positions are attached oxyacetic acid or N-(X)sulfonyl oxyacetamide groups. Changing the conformation varies the spatial relationship between a polyether-complexed divalent metal ion and the ionized side arms of the ligands. This is found to markedly affect the efficiency and selectivity in competitive solvent extraction of alkaline earth metal ions from aqueous solutions into chloroform by the di-ionizable calix[4]arene-crown-6 ligands.
Co-reporter:Christopher M. Stetson;Shiro Nishikawa;David W. Purkiss;N. Kent Dalley;Richard A. Bartsch
Journal of Physical Organic Chemistry 2005 Volume 18(Issue 11) pp:1107-1115
Publication Date(Web):8 AUG 2005
DOI:10.1002/poc.981
As potential receptors for a benzoic acid guest, new ditopic cyclophane host molecules, each with a π electron-rich portion and a pyridine ring-containing portion, are synthesized. Complexation of benzoic acid guest by the potential molecular receptors is probed by infrared spectroscopy, proton magnetic resonance titration experiments and solid-state structure determination. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:Galina G. Talanova, Vladimir S. Talanov, Hong-Sik Hwang, Chunkyung Park, Kazimierz Surowiec and Richard A. Bartsch
Organic & Biomolecular Chemistry 2004 vol. 2(Issue 18) pp:2585-2592
Publication Date(Web):23 Aug 2004
DOI:10.1039/B407812H
For an assessment of the outcomes from use of an appropriately “preorganized” calixarene-based ionophore versus its conformationally mobile prototype, solvent extraction propensities of flexible calix[4]arene di-[N-(X-sulfonyl)carboxamides] for alkali, alkaline earth metal cations, Pb2+, Ag+ and Hg2+ are compared with those for seven new rigid analogs fixed in the cone, partial cone and 1,3-alternate conformations. For each of the metal ions, the preferred calix[4]arene conformation was determined from the NMR spectra for the metal salt of the flexible ligand. Except for Ag+, flexible calix[4]arene di-[N-(X-sulfonyl)carboxamides] were found to provide greater metal ion extraction efficiency and better selectivity than the corresponding “preorganized” ionophores.
Co-reporter:Sergei V. Dzyuba Dr.;Richard A. Bartsch
Angewandte Chemie International Edition 2003 Volume 42(Issue 2) pp:
Publication Date(Web):16 JAN 2003
DOI:10.1002/anie.200390070
Duet of Extremes: Efficient and environmentally benign, biphasic systems consisting of ionic liquids and supercritical CO2 (scCO2) have been employed in lipase-catalyzed esterifications (see scheme). The reaction takes place in the ionic liquid with or without a solid support, and the products are removed by means of either batchwise or continuous-flow extraction with supercritical CO2.
Co-reporter:Sergei V. Dzyuba Dr.;Richard A. Bartsch
Angewandte Chemie 2003 Volume 115(Issue 2) pp:
Publication Date(Web):16 JAN 2003
DOI:10.1002/ange.200390038
Ein Duett der Extreme: Zweiphasensysteme aus ionischen Flüssigkeiten und überkritischem CO2 (scCO2) wurden für Lipase-katalysierte Veresterungen eingesetzt (siehe Schema). Die Komponenten reagieren dabei in der ionischen Flüssigkeit an einem festen Träger oder ohne Trägermaterial; die Produkte werden mit scCO2 im Batch- oder Durchflussverfahren extrahiert.
Co-reporter:Galina G. Talanova, Vladimir S. Talanov, Maryna G. Gorbunova, Hong-Sik Hwang and Richard A. Bartsch
Organic & Biomolecular Chemistry 2002 (Issue 12) pp:2072-2077
Publication Date(Web):2002/11/22
DOI:10.1039/B207301C
A series of new di-ionizable calix[4]arene N-(X-sulfonyl)carboxamides (X = CF3, Me, Ph and C6H4-4-NO2) and carboxylic acids with partially and completely removed upper rim p-tert-butyl groups was synthesized and utilized for competitive solvent extractions of alkali and alkaline earth metal cations. Removal of the para-alkyl substituents changes significantly both the efficiency and selectivity of metal ion separations by the carboxamide calix[4]arene extractants, while no such effect is observed for corresponding carboxylic acids.
Co-reporter:Galina G. Talanova, Vladimir S. Talanov, Hong-Sik Hwang, Bijan A. Eliasi and Richard A. Bartsch
Organic & Biomolecular Chemistry 2002 (Issue 11) pp:1869-1874
Publication Date(Web):17 Sep 2002
DOI:10.1039/B206484G
A series of new mono-ionizable cone calix[4]arenes, with either a pendent carboxylic acid or a N-(X-sulfonyl)carboxamide group, is synthesized and their alkali metal cation extraction behavior determined and compared with that for conformationally mobile analogues. These new proton-ionizable, cone calixarenes exhibit good (for the sulfonylcarboxamides) to excellent (for the carboxylic acid) Li+-selectivity. Surprisingly, the Li+-selectivity decreases on going from the conformationally flexible to the cone ionophores due to enhanced Na+ binding by the latter. During the ligand synthesis, unusual behavior of cone tributoxy-N-(trifluoromethylsulfonyl)carbamoylmethoxy-p-tert-butylcalix[4]arene suggests a strong tendency for molecular association.
Co-reporter:Vladimir S. Talanov, Galina G. Talanova, Maryna G. Gorbunova and Richard A. Bartsch
Organic & Biomolecular Chemistry 2002 (Issue 2) pp:209-215
Publication Date(Web):11 Jan 2002
DOI:10.1039/B109638A
Synthesis of a series of novel 1,3-alternate calix[4]arene-bis(crown-6-ethers) with a proton-ionizable group (PIG) located in front of one crown ether cavity is reported. Variation of the X group in the N-(X-sulfonyl)carbamoyl substituent on the calixbiscrowns provides variation of acidity of the PIG. NMR spectroscopic studies demonstrate that the position of the PIG within the molecule allows it to participate in cooperative metal ion coordination by the ligand. In solvent extraction of alkali metal cations from aqueous solutions of varying pH into chloroform, the novel ionophores possess enhanced efficiency relative to a non-ionizable analog, while retaining high Cs+ selectivity. The Cs+ extraction constants of the proton-ionizable calixbiscrowns are proportional to their acidities. Under the conditions employed, 1 ∶ 1 complexes of the ionized calixbiscrowns with Cs+ are the dominant species extracted into the
organic phase.
Co-reporter:Sergei V. Dzyuba;Richard A. Bartsch Dr.
ChemPhysChem 2002 Volume 3(Issue 2) pp:
Publication Date(Web):14 FEB 2002
DOI:10.1002/1439-7641(20020215)3:2<161::AID-CPHC161>3.0.CO;2-3
A series of twenty four 1-alkyl(aralkyl)-3-methylimidazolium hexafluorophosphates and bis(trifluoromethyl-sulfonyl)imides are prepared and the influence of structural variations in the imidazolium cation and the identity of the anion on physical properties (phase transition, density, viscosity, and surface tension) of the ionic liquids is determined.
Co-reporter:Sergei V. Dzyuba and Richard A. Bartsch
Chemical Communications 2001 (Issue 16) pp:1466-1467
Publication Date(Web):23 Jul 2001
DOI:10.1039/B104512C
New 1,3-dialkylimidazolium hexafluorophosphates with two
butyl, pentyl, octyl, nonyl or decyl groups are room temperature ionic
liquids.
Co-reporter:Hui Zhou, Dazhan Liu, Jerzy Gega, Kazimierz Surowiec, David W. Purkiss and Richard A. Bartsch
Organic & Biomolecular Chemistry 2007 - vol. 5(Issue 2) pp:NaN332-332
Publication Date(Web):2006/11/24
DOI:10.1039/B611570E
Two carboxylic acid or N-(X)sulfonyl carboxamide groups were incorporated into calix[4]arene-crown-6 compounds to afford di-ionizable ligands for use in divalent metal ion separations. Acidities of the N-(X)sulfonyl carboxamide groups were tuned by variation of the electron-withdrawing properties of X. Cone, partial-cone and 1,3-alternate conformations were obtained by different synthetic strategies and their structures verified by NMR spectroscopy. Competitive solvent extractions of alkaline earth metal cations from aqueous solutions into chloroform were performed and the results compared with those reported previously for di-ionizable p-tert-butylcalix[4]arene-crown-6 analogues to probe the influence of the para-substituent on the calix[4]arene scaffold on extraction selectivity and efficiency.
Co-reporter:Dongmei Zhang, Xiaodan Cao, David W. Purkiss and Richard. A. Bartsch
Organic & Biomolecular Chemistry 2007 - vol. 5(Issue 8) pp:NaN1259-1259
Publication Date(Web):2007/03/19
DOI:10.1039/B700072C
Novel di-ionizable p-tert-butylcalix[4]arene-1,2-crown-3 ligands in cone and 1,2-alternate conformations were prepared as potential metal ion extractants. Selective bridging of proximal hydroxyl groups of the calix[4]arene platform by a crown-3 polyether unit was achieved under Mitsunobu reaction conditions. In addition to the carboxylic acid group, the acidity tunable N-(X)sulfonyl oxyacetamide functions [OCH2C(O)NHSO2X] with X group variation from methyl to phenyl to p-nitrophenyl to trifluomethyl were used as the proton-ionizable groups. Conformations and regioselectivities of the new ligands were established by 1H and 13C NMR spectroscopy. Competitive solvent extractions of alkali metal cations and of alkaline earth metal cations from aqueous solutions into chloroform were performed, as were single species extractions of lead(II) and mercury(II).
![Pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,27-diol, 26,28-dimethoxy-](/data/chemimg/3724200/142433-64-5.png)
![Pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,27-diol, 26,28-dimethoxy-](/data/chemimg/3724200/142433-64-5_b.png)
![Pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,26-diol, 5,11,17,23-tetrakis(1,1-dimethylethyl)-27,28-dimethoxy-](/data/chemimg/3724200/126109-82-8.png)
![Pentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,26-diol, 5,11,17,23-tetrakis(1,1-dimethylethyl)-27,28-dimethoxy-](/data/chemimg/3724200/126109-82-8_b.png)
![Acetamide, 2,2'-[[5,11,17,23-tetrakis(1,1-dimethylethyl)-26,28-dimethoxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,27-diyl]bis(oxy)]bis[N-[(trifluoromethyl)sulfonyl]-](/data/chemimg/3724300/204119-61-9.png)
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