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RISS 인기검색어
- 검색키워드
- 저자 : Delmau, Lætitia H. (검색결과 2 건)
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Kim, Sung Kuk,Sessler, Jonathan L.,Gross, Dustin E.,Lee, Chang-Hee,Kim, Jong Seung,Lynch, Vincent M.,Delmau, Lætitia H.,Hay, Benjamin P. American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.16
<P>An ion-pair receptor, the calix[4]pyrrole-calix[4]arene pseudodimer <B>2</B>, bearing a strong anion-recognition site but not a weak cation-recognition site, has been synthesized and characterized by standard spectroscopic means and <I>via</I> single-crystal X-ray diffraction analysis. In 10% CD<SUB>3</SUB>OD in CDCl<SUB>3</SUB> (v/v), this new receptor binds neither the Cs<SUP>+</SUP> cation nor the F<SUP>−</SUP> anion when exposed to these species in the presence of other counterions; however, it forms a stable 1:1 solvent-separated CsF complex when exposed to these two ions in concert with one another in this same solvent mixture. In contrast to what is seen in the case of a previously reported crown ether “strapped” calixarene−calixpyrrole ion-pair receptor <B>1</B> (J. Am. Chem. Soc. 2008, 130, 13162−<lpage>13166</lpage>), where Cs<SUP>+</SUP> cation recognition takes place within the crown, in <B>2</B>·CsF cation recognition takes place within the receptor cavity itself, as inferred from both single-crystal X-ray diffraction analyses and <SUP>1</SUP>H NMR spectroscopic studies. This binding mode is supported by calculations carried out using the MMFF94 force field model. In 10% CD<SUB>3</SUB>OD in CDCl<SUB>3</SUB> (v/v), receptor <B>2</B> shows selectivity for CsF over the Cs<SUP>+</SUP> salts of Cl<SUP>−</SUP>, Br<SUP>−</SUP>, and NO<SUB>3</SUB><SUP>−</SUP> but will bind these other cesium salts in the absence of fluoride, both in solution and in the solid state. In the case of CsCl, an unprecedented 2:2 complex is observed in the solid state that is characterized by two different ion-pair binding modes. One of these consists of a contact ion pair with the cesium cation and chloride anion both being bound within the central binding pocket and in direct contact with one another. The other mode involves a chloride anion bound to the pyrrole NH protons of a calixpyrrole subunit and a cesium cation sandwiched between two cone shaped calix[4]pyrroles originating from separate receptor units. In contrast to what is seen for CsF and CsCl, single-crystal X-ray structural analyses and <SUP>1</SUP>H NMR spectroscopic studies reveal that receptor <B>2</B> forms a 1:1 complex with CsNO<SUB>3</SUB>, with the ions bound in the form of a contact ion pair. Thus, depending on the counteranion, receptor <B>2</B> is able to stabilize three different ion-pair binding modes with Cs<SUP>+</SUP>, namely solvent-bridged, contact, and host-separated.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-16/ja100715e/production/images/medium/ja-2010-00715e_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja100715e'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja100715e'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja100715e'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja100715e'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja100715e'>ACS Electronic Supporting Info</A></P>
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Controlling Cesium CationRecognition via Cation Metathesiswithin an Ion Pair Receptor
Kim, Sung Kuk,Vargas-Zú,ñ,iga, GabrielaI.,Hay, Benjamin P.,Young, Neil J.,Delmau, Lætitia H.,Masselin, Charles,Lee, Chang-Hee,Kim, Jong Seung,Lynch, VincentM.,Moyer, Bruce A.,Sessler, Jona American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.3
<P>Ion pair receptor 3 bearing an anion binding site and multiple cation binding sites has been synthesized and shown to function in a novel binding-release cycle that does not necessarily require displacement to effect release. The receptor forms stable complexes with the test cesium salts, CsCl and CsNO3, in solution (10% methanol-d(4) in chloroform-d) as inferred from H-1 NMR spectroscopic analyses. The addition of KClO4 to these cesium salt complexes leads to a novel type of cation metathesis in which the 'exchanged' cations occupy different binding sites. Specifically, K+ becomes bound at the expense of the Cs+ cation initially present in the complex. Under liquid liquid conditions, receptor 3 is able to extract CsNO3 and CsCl from an aqueous D2O layer into nitrobenzene-d(5) as inferred from H-1 NMR spectroscopic analyses and radiotracer measurements. The Cs+ cation of the CsNO3 extracted into the nitrobenzene phase by receptor 3 may be released into the aqueous phase by contacting the loaded nitrobenzene phase with an aqueous KClO4 solution. Additional exposure of the nitrobenzene layer to chloroform and water gives 3 in its uncomplexed, ion-free form. This allows receptor 3 to be recovered for subsequent use. Support for the underlying complexation chemistry came from single-crystal X-ray diffraction analyses and gas-phase energy-minimization studies.</P>
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