Anion-binding behavior of hybrid calixpyrroles.
Hybrid calixpyrrole systems are calixpyrrole-like macrocycles that are based on more than one type of small molecule building block. Structurally, these "mixed-breed" macrocycles differ from calixpyrroles in that some pyrrolic units in the latter are replaced by other hetereocyclic units such as furan, thiophene, bipyrrole, and bithiophene. Although several such systems have been reported in recent years, only a few have been studied as possible anion receptors. In this paper, the results of detailed anion binding studies involving several prototypic systems are reported. Taken in concert, these results highlight the fact that some hybrid systems, including compounds 2-5, display anion affinities that are considerably weaker than those of the parent system 1. On the other hand, they also show that compounds 6-8 are good receptors for "Y-shaped" anions, such as carboxylates, and that they bind these species with high affinity. These findings are strongly supported by solid-state structural studies, which reveal an interesting "cross binding mode" for the binding of carboxylate anions by the bis-thiophene, bis-pyrrole system 7.
Sessler
Jonathan L
JL
Department of Chemistry and Biochemistry, Institute of Cellular and Molecular Biology, The University of Texas at Austin, 1 University Station--A5300, Austin, Texas 78712-1167, USA. sessler@mail.utexas.edu
An
Deqiang
D
Cho
Won-Seob
WS
Lynch
Vincent
V
Yoon
Dae-Wi
DW
Hong
Seong-Jin
SJ
Lee
Chang-Hee
CH
D000838:Anions / Q000737:chemistry*; D047250:Calixarenes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D047028:Macrocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D046911:Macromolecular Substances; D008956:Models, Chemical; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis / Q000737:chemistry*
D000838:Anions; D047028:Macrocyclic Compounds; D046911:Macromolecular Substances; D011758:Pyrroles; D047250:Calixarenes