More Like this

1. Macrocyclic and acyclic supramolecular elements for co-precipitation of square-planar gold( iii ) tetrahalide complexes

   https://doi.org/10.1039/D0QO01562H  

   Shaffer, Cassandra C.; Smith, Bradley D. (March 2021, Organic Chemistry Frontiers)

   null (Ed.)

   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. 

   more » « less
2. π-Complexation and C—H hydrogen bonding in the formation of colored cocrystals

   https://doi.org/10.1107/S2053229623002231  

   Bosch, Eric; Moreno, Bryce S.; Bowling, Nathan P. (April 2023, Acta Crystallographica Section C Structural Chemistry)

   The present study evaluates the potential combination of charge-transfer electron-donor–acceptor π–π complexation and C—H hydrogen bonding to form colored cocrystals. The crystal structures of the red 1:1 cocrystals formed from the isomeric pyridines 4- and 3-{2-[4-(dimethylamino)phenyl]ethynyl}pyridine with 1-[2-(3,5-dinitrophenyl)ethynyl]-2,3,5,6-tetrafluorobenzene, both C 14 H 4 F 4 N 2 O 4 ·C 15 H 14 N 2 , are reported. Intermolecular interaction energy calculations confirm that π-stacking interactions dominate the intermolecular interactions within each crystal structure. The close contacts revealed by Hirshfeld surface calculations are predominantly C—H interactions with N, O, and F atoms. 

   more » « less
3. Anion⋯anion (MX ₃ ⁻ ) ₂ dimers (M = Zn, Cd, Hg; X = Cl, Br, I) in different environments

   https://doi.org/10.1039/D1CP01502H  

   Wysokiński, Rafał; Zierkiewicz, Wiktor; Michalczyk, Mariusz; Scheiner, Steve (July 2021, Physical Chemistry Chemical Physics)

   The possibility that MX 3 − anions can interact with one another is assessed via ab initio calculations in gas phase as well as in aqueous and ethanol solution. A pair of such anions can engage in two different dimer types. In the bridged configuration, two X atoms engage with two M atoms in a rhomboid structure with four equal M–X bond lengths. The two monomers retain their identity in the stacked geometry which contains a pair of noncovalent M⋯X interactions. The relative stabilities of these two structures depend on the nature of the central M atom, the halogen substituent, and the presence of solvent. The interaction and binding energies are fairly small, generally no more than 10 kcal mol −1 . The large electrostatic repulsion is balanced by a strong attractive polarization energy. 

   more » « less
4. Redox-gated recognition of dihydrogen phosphate using a ferrocene-tethered non-symmetric aryl-triazole pentad

   https://doi.org/10.1080/10610278.2024.2326525  

   Bhattacharjee, Nabarupa; Nathani, Akash; Unzaga, James B; Ito, Takashi; Flood, Amar H (March 2024, Supramolecular Chemistry)

   Anions play many roles in our environment. Consequently, the development of synthetic receptors capable of targeted anion binding is of ongoing importance. While many such receptors are known, simplified designs and measurement approaches are always beneficial. Herein, we report the synthesis of a non-symmetric aryl-triazole pentad receptor appended with a single ferrocene, its electrochemistry, and the selective binding to dihydrogen phosphate (H2PO4–) anions of its oxidized form over various environmentally prevalent anions (HSO4–, Cl–, NO3–). The receptor was constructed using a modular architecture with simple installation of a ferrocene unit using click chemistry. Electrochemical analysis on the receptor revealed that addition of H2PO4– anion led to a shift in the redox peaks of the receptor (FcP) towards more negative potentials, indicating higher anion affinity was achieved after the ferrocene was oxidized to its cationic form (FcP+). This work verifies prior studies on the efficacy of cationic charge in simpler receptor design for the creation of functional host-guest systems. 

   more » « less
5. Impact of Guest Orientation in Host–Guest Supramolecular Hydrogels

   https://doi.org/10.1021/acsmacrolett.4c00531  

   Addonizio, Christopher J; Braegelman, Adam S; Schmidt, Connor R; Ollier, Rachel C; Antwi, Akwasi Ansah; Su, Bo; Farshad, Mohsen; Whitmer, Jonathan K; Webber, Matthew J (January 2025, ACS Macro Letters)

   Host–guest interactions have been increasingly explored for use in the dynamic physical crosslinking of polymeric precursors to form hydrogel networks. However, the orientation of guest motifs is restricted upon macromolecule conjugation. The implications of such restriction on both the kinetics and thermodynamics of the resulting host–guest supramolecular crosslinks are poorly understood. Herein, guest crosslinking motifs from controlled regioisomers are demonstrated to yield distinct material properties. Moreover, the underlying phenomena point to further unexpected impact of modular guest topology manifest on the molecular scale in both the affinity and dynamics of supramolecular complex formation. 

   more » « less