{"title":"通过水溶性钙[4]吡咯的预组织增强甲基烷基铵阳离子的结合力。","authors":"Esteban Valencia, Pablo Ballester","doi":"10.1039/d4ob00843j","DOIUrl":null,"url":null,"abstract":"<p><p>We describe the synthesis of two tetra-α aryl-extended calix[4]pyrroles (C[4]Ps) 4a-b bearing four terminal carboxylic groups in their <i>meso</i>-propyl chains defining the lower rims. The synthesized C[4]Ps became soluble (1-3 mM) in water at pD = 10. We probed the interaction of 4a towards tetra-methylammonium (G1) chloride in water using <sup>1</sup>H NMR spectroscopy. The C[4]P 4a includes G1 in the shallow aromatic cavity defined by the pyrrole rings in cone conformation forming a 1 : 1 complex G1⊂4a. Pyridine-<i>N</i>-oxide (PNO) binding in the larger polar aromatic cavity of 4a results in the quantitative self-assembly of the supramolecular receptor PNO@4a featuring the pyrrole rings preorganized in cone conformation. The PNO@4a receptor displays improved binding properties towards G1 than the parent C[4]P 4a. We thermodynamically characterized (<sup>1</sup>H NMR titrations and ITC experiments) the 1 : 1 complexes of PNO@4a with a series of tetra-alkylammonium salts, including biologically relevant examples. The PNO@4a supramolecular receptor displays significant affinity (log <i>K</i> = 3-4) but lacks selectivity in water binding of methyl trialkyl ammonium cations. Cation-π and coulombic interactions are the main intermolecular forces stabilizing the complexes. We also performed DFT calculations to gain some insights into the complexes' structures.</p>","PeriodicalId":96,"journal":{"name":"Organic & Biomolecular Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Enhanced binding of methyl alkylammonium cations through preorganization of a water-soluble calix[4]pyrrole.\",\"authors\":\"Esteban Valencia, Pablo Ballester\",\"doi\":\"10.1039/d4ob00843j\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>We describe the synthesis of two tetra-α aryl-extended calix[4]pyrroles (C[4]Ps) 4a-b bearing four terminal carboxylic groups in their <i>meso</i>-propyl chains defining the lower rims. The synthesized C[4]Ps became soluble (1-3 mM) in water at pD = 10. We probed the interaction of 4a towards tetra-methylammonium (G1) chloride in water using <sup>1</sup>H NMR spectroscopy. The C[4]P 4a includes G1 in the shallow aromatic cavity defined by the pyrrole rings in cone conformation forming a 1 : 1 complex G1⊂4a. Pyridine-<i>N</i>-oxide (PNO) binding in the larger polar aromatic cavity of 4a results in the quantitative self-assembly of the supramolecular receptor PNO@4a featuring the pyrrole rings preorganized in cone conformation. The PNO@4a receptor displays improved binding properties towards G1 than the parent C[4]P 4a. We thermodynamically characterized (<sup>1</sup>H NMR titrations and ITC experiments) the 1 : 1 complexes of PNO@4a with a series of tetra-alkylammonium salts, including biologically relevant examples. The PNO@4a supramolecular receptor displays significant affinity (log <i>K</i> = 3-4) but lacks selectivity in water binding of methyl trialkyl ammonium cations. Cation-π and coulombic interactions are the main intermolecular forces stabilizing the complexes. We also performed DFT calculations to gain some insights into the complexes' structures.</p>\",\"PeriodicalId\":96,\"journal\":{\"name\":\"Organic & Biomolecular Chemistry\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.9000,\"publicationDate\":\"2024-07-03\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Organic & Biomolecular Chemistry\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://doi.org/10.1039/d4ob00843j\",\"RegionNum\":3,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, ORGANIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organic & Biomolecular Chemistry","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d4ob00843j","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
Enhanced binding of methyl alkylammonium cations through preorganization of a water-soluble calix[4]pyrrole.
We describe the synthesis of two tetra-α aryl-extended calix[4]pyrroles (C[4]Ps) 4a-b bearing four terminal carboxylic groups in their meso-propyl chains defining the lower rims. The synthesized C[4]Ps became soluble (1-3 mM) in water at pD = 10. We probed the interaction of 4a towards tetra-methylammonium (G1) chloride in water using 1H NMR spectroscopy. The C[4]P 4a includes G1 in the shallow aromatic cavity defined by the pyrrole rings in cone conformation forming a 1 : 1 complex G1⊂4a. Pyridine-N-oxide (PNO) binding in the larger polar aromatic cavity of 4a results in the quantitative self-assembly of the supramolecular receptor PNO@4a featuring the pyrrole rings preorganized in cone conformation. The PNO@4a receptor displays improved binding properties towards G1 than the parent C[4]P 4a. We thermodynamically characterized (1H NMR titrations and ITC experiments) the 1 : 1 complexes of PNO@4a with a series of tetra-alkylammonium salts, including biologically relevant examples. The PNO@4a supramolecular receptor displays significant affinity (log K = 3-4) but lacks selectivity in water binding of methyl trialkyl ammonium cations. Cation-π and coulombic interactions are the main intermolecular forces stabilizing the complexes. We also performed DFT calculations to gain some insights into the complexes' structures.