Danil de Namor Angela F, Shehab Mohammed
Laboratory of Thermochemistry, Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom.
J Phys Chem B. 2005 Sep 22;109(37):17440-4. doi: 10.1021/jp0530707.
A double-cavity calix[4]pyrrole derivative, meso-tetramethyl-tetra[N-(2-phenoxyethyl)-N'-phenylurea]calix[4]pyrrole, 1, with enhanced hosting ability for the fluoride anion has been designed and characterized. Its interaction with anions (fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulfate, perchlorate, nitrate, and trifluoromethane sulfonate) was qualitatively and quantitatively assessed through 1H NMR, conductance, and calorimetric studies. The outcome of these investigations demonstrates that 1 interacts only with fluoride and dihydrogen phosphate anions in dipolar aprotic media. However, the composition of these complexes differs in that two units of fluoride are taken per unit of 1, while a 1:1 anion/ligand complex is formed with the dihydrogen phosphate anion. Results from the 1H NMR studies are striking in that these not only provide information about the active sites of the ligand-anion interaction but also allow the establishment of the sequence of events taking place during fluoride complexation. Thus, hydrogen-bond formation between the pyrrolic hydrogen and the fluoride anion is followed by the uptake of a second anion through the same type of interaction, but with the phenyl urea. It is also the latter group that is responsible for the interaction of 1 with the dihydrogen phosphate anion. Finally, this paper illustrates the importance of structural information for the interpretation of the thermodynamics associated with these systems.
一种双腔杯[4]吡咯衍生物，即中-四甲基-四[N-(2-苯氧基乙基)-N'-苯基脲]杯[4]吡咯（1），已被设计并表征，其对氟阴离子具有增强的容纳能力。通过1H NMR、电导率和量热研究对其与阴离子（氟化物、氯化物、溴化物、碘化物、磷酸二氢根、硫酸氢根、高氯酸根、硝酸根和三氟甲磺酸根）的相互作用进行了定性和定量评估。这些研究结果表明，在偶极非质子介质中，1仅与氟化物和磷酸二氢根阴离子相互作用。然而，这些配合物的组成不同，每单位1会结合两个单位的氟化物，而与磷酸二氢根阴离子形成1:1的阴离子/配体配合物。1H NMR研究结果令人惊讶，因为这些结果不仅提供了关于配体-阴离子相互作用活性位点的信息，还能确定氟化物络合过程中发生的一系列事件。因此，吡咯氢与氟阴离子之间形成氢键后，会通过相同类型的相互作用（但与苯基脲）吸收第二个阴离子。也是后一组基团负责1与磷酸二氢根阴离子的相互作用。最后，本文说明了结构信息对于解释与这些系统相关的热力学的重要性。
