title: "Texas-sized" molecular boxes: building blocks for the construction of anion-induced supramolecular species via self-assembly.
abstract: It was previously established that the flexible tetraimidazolium macrocycle cyclo[2](2,6-bis(1H-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene) (1(4+)) is capable of stabilizing higher-order supramolecular structures via both anion and cation recognition. Described herein is a set of structurally related imidazolium macrocycles (2(4+)-4(4+)) that contain modified central cores. The flexible nature of these new constructs is highlighted by the isolation of several independent crystalline forms for the same basic structure. Each of the individual receptors was found to bind the 2,6-naphthalenedicarboxylate dianion and to stabilize the formation of self-associated structures. The observed binding modes and resulting supramolecular organizational forms were found to differ dramatically depending on the nature of the bridging group present in the imidazolium macrocycle. This finding was established by solution studies involving, inter alia, one- and two-dimensional ((1)H, (1)H-(1)H COSY, DOSY, and NOESY) NMR spectroscopy as well as electrospray ionization mass spectrometry. The new systems in this report serve to expand the available "tool box" for the construction of complex self-assembled materials while providing insights into the determinants that regulate the formation of specific supramolecular structures from flexible receptors capable of adopting multiple stable conformations.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Texas at Austin, Welch Hall 2.204, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, USA. hyg2070@iccas.ac.cn
authors.forename: Han-Yuan
authors.initials: HY
authors.lastname: Gong
authors.forename: Brett M
authors.initials: BM
authors.lastname: Rambo
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Lynch
authors.forename: Karin M
authors.initials: KM
authors.lastname: Keller
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Sessler
mesh_terms: D000838:Anions / Q000737:chemistry; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000138:chemical synthesis; D007202:Indicators and Reagents; D047028:Macrocyclic Compounds / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D008968:Molecular Conformation; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000838:Anions; D007093:Imidazoles; D007202:Indicators and Reagents; D047028:Macrocyclic Compounds