Structurally elusive inositol hexakisphosphates have been trapped in host–guest sandwiches between two picolinamide macrocycles that remain intact in solution, aided by hydrogen bonds and electrostatic interactions. This first report of macrocyclic complexes of inositol hexakisphosphates provides structural insight to significant biosources of phosphorus that impact the global phosphorus cycle.
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Macrocyclic and acyclic supramolecular elements for co-precipitation of square-planar gold( iii ) tetrahalide complexes
Macrocyclic hosts have long been used for guest encapsulation, and recently a new application has emerged; employment as supramolecular elements for capture and recovery of gold through host/guest co-precipitation. The guests are square-planar tetrahaloaurate anions, practically important gold complexes with a capacity to engage in non-covalent interactions such as hydrogen bonding and Au–π interactions. The successful macrocyclic hosts for co-precipitation include cyclodextrins, cucurbiturils, and cyclophanes, with recent expansion of the structural scope to include acyclic amides.
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- Award ID(s):
- 1708240
- PAR ID:
- 10281818
- Date Published:
- Journal Name:
- Organic Chemistry Frontiers
- Volume:
- 8
- Issue:
- 6
- ISSN:
- 2052-4129
- Page Range / eLocation ID:
- 1294 to 1301
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The self‐assembly in aqueous solution of the well‐known cyclophane, cyclobis(paraquat‐p‐phenylene) (BB4+), and two cucurbit[7]uril (CB7) hosts around a simple hydroquinol‐based, diamine guest (GH22+) was investigated by1H NMR and electronic absorption spectroscopies, electrospray mass spectrometry and DFT computations. The formation of a quaternary supramolecular assembly [GH22+⋅BB4+⋅ (CB7)2] was shown to be a very efficient process, which takes place not only because of the attractive forces between each of the hosts and the guest, but also because of the lateral interactions between the hosts in the final assembly. This complementary set of attractive interactions results in clear cooperative binding effects that help overcome the entropic barriers for multiple component assembly.
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A supramolecular dye-capture system comprising anionic amidosquaraine guest and macrocyclic tetralactam host exhibits nanomolar affinity and “turn on” visible fluorescence. Utility is demonstrated with a new fluorescent assay for liposome leakage induced by the biomedically important enzyme phospholipase A 2 .more » « less
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null (Ed.)Two five-coordinate mononuclear Co( ii ) complexes [Co(12-TMC)X][B(C 6 H 5 ) 4 ] (L = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane (12-TMC), X = Cl − ( 1 ), Br − ( 2 )) have been studied by X-ray single crystallography, magnetic measurements, high-frequency and -field EPR (HF-EPR) spectroscopy and theoretical calculations. Both complexes have a distorted square pyramidal geometry with the Co( ii ) ion lying above the basal plane constrained by the rigid tetradentate macrocyclic ligand. In contrast to the reported five-coordinate Co( ii ) complex [Co(12-TMC)(NCO)][B(C 6 H 5 ) 4 ] ( 3 ) exhibiting easy-axis anisotropy, an easy-plane magnetic anisotropy was found for 1 and 2 via the analyses of the direct-current magnetic data and HF-EPR spectroscopy. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements demonstrated that complexes 1 and 2 show slow magnetic relaxation at an applied dc field. Ab initio calculations were performed to reveal the impact of the terminal ligands on the nature of the magnetic anisotropies of this series of five-coordinate Co( ii ) complexes.more » « less
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Abstract We report that the direct macrocyclization of naphthalene monomers bearing ethyl ester functional groups delivers prism[5]arene derivatives, which can be deprotected to yield water‐soluble prism[5]arenes (
H1 andH3 ).1H NMR spectroscopy showed that dicationic guests bind with the hydrophobic cores buried inside the anisotropic magnetically shielding cavity. Isothermal titration calorimetry measurements showed thatH1 andH3 are high‐affinity hosts in PBS‐buffered water with Kavalues exceeding 109 M−1for a select guest. The complexation events are driven by the non‐classical hydrophobic effect, CH⋅⋅⋅π interactions, and electrostatic interactions. HostH1 displays somewhat higher affinity toward a common guest than pillar[6]arene bearing carboxylic acid functional groups but is significantly less potent than pillar[6]arene bearing sulfate groups.H1 andH3 should be considered alongside other high affinity hosts for a variety of chemical and biological applications.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0QO01562H
