Cis- and Trans-Strapped Calix[4]pyrroles Bearing Phthalamide Linkers:  Synthesis and Anion-Binding Properties

• Published in: Journal of organic chemistry Vol. 70; no. 6; pp. 2067 - 2074
• Main Authors: Lee, Chang-Hee, Lee, Jin-Suk, Na, Hee-Kyung, Yoon, Dae-Wi, Miyaji, Hidekazu, Cho, Won-Seob, Sessler, Jonathan L.
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 18.03.2005; Amer Chemical Soc
• Subjects: Anions - chemistry; Calixarenes - chemical synthesis; Calixarenes - chemistry; Chemistry; Chemistry, Organic; Exact sciences and technology; Halogens - chemistry; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Models, Chemical; Molecular Conformation; Organic chemistry; Phthalimides - chemistry; Physical Sciences; Porphyrins - chemical synthesis; Porphyrins - chemistry; Preparations and properties; Science & Technology; Stereoisomerism; CALIX PYRROLES; AGENTS; RECOGNITION; SENSORS; CALIXPYRROLE; Nitrogen heterocycle; Molecular interaction; NMR spectrometry; Calixarene; Pyrrole derivatives; Characterization; Anions; Halides; Affinity; Calorimetry; Carboxamide; Chemical synthesis; Hydrogen bond
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo0487146

New cis-strapped calix[4]pyrrole derivatives 12, 13, and 19 and trans-strapped systems 14 and 15 bearing isophthalate-derived diamide spacers linked to the tetrapyrrolic core have been synthesized and characterized by spectroscopic means. The anion-binding behavior of these receptors was investigated by proton NMR spectroscopy and isothermal titration calorimetry (ITC). A 2:1 binding stoichiometry was observed under the conditions of NMR analysis but not at the lower concentration regime used for ITC. As gauged from both sets of analyses, these new strapped systems display affinities for halide anions that are enhanced compared to those of normal, unstrapped calix[4]pyrrole. However, contrary to expectations, no size-dependent selectivity for anions is observed as the length of the bridging strap is varied. Such results are interpreted in terms of anion-binding processes that occur outside the central pocket defined by the strap but that still favor strong associations as the result of the increased number of hydrogen-bonding donors the amide groups provide.