Micromolar Affinity and Higher: Synthetic Host–Guest Complexes with High Stabilities

Abstract

The design of high-affinity synthetic host-guest complexes is of paramount importance because they are key elements in constructing unprecedented supramolecular assemblies, functional materials, molecular probes, artificial signal transduction events, and interfaces with the biological world. The present review article collects recent achievements in the design of 1 : 1 host-guest complexes with outstanding stabilities, i.e., exceeding 10 6 M À 1 . The relationships between the measured thermodynamic constants and the structural parameters of the interacting species are analyzed. The design features of high-affinity hosts are discussed in light of their binding properties. Different solvents and different types of noncovalent interactions are considered for the stabilization of the complexes. Finally, some hints are provided for the design of future synthetic receptors displaying high affinity and selectivity.

Advanced supramolecular design for direct ink writing of soft materials

“…Notable examples include crownether/ammonium-based polymers, 115,130,261 cucurbituril-based host-guest polymers, 122 polymers with self-complementary hydrogen bonding motifs, 74,112 and supramolecular systems that are connected via halogen bonds [262][263][264][265][266] and chalcogen bonds. 267,268 Introducing high-affinity binding motifs in the construction of DIW inks is another promising strategy, 269 allowing for the formation of 3D-printable inks at lower concentrations. The multivalency and positive cooperativity 83 in supramolecular binding are also helpful in the DIW ink designs.…”

C64 Nanographene Tetraimide—A Receptor for Phthalocyanines with Subnanomolar Affinity

“…[9] Inspired by reported examples for high affinity synthetic hosts [10] and our earlier work on the binding of polycyclic aromatic hydrocarbons by expanded πreceptors [11,12] we hypothesized that such electron-deficient π-receptors should be able to dissolve also monomeric unsubstituted Pc compounds into solution phase. [10] Here we show that C 64 nanographene tetraimide 1 can bind unsubstituted Pcs and MPcs and keep them dissolved in organic solvents by supramolecular host-guest interactions. The structural evidence obtained by 1 H NMR experiments at slow exchange regime and single crystal X-ray analysis revealed a 1 : 2 stoichiometric complex formation.…”

“…Thus, our binding affinity investigations showed that the solubilization of Pc1 by 1 originates from the ultra‐strong binding of 1 towards Pc1 . Such a high binding strength is unusual for apolar molecules in apolar solvents [10a, 19] especially for multiple guest binding [20]…”

“…[8] Dissolving such insoluble Pcs in their monomeric form in solution is important but challenging due to strong intermolecular interactions between these extended planar π-systems and the resulting thermodynamically very stable non-meltable crystalline state (sublimation temperatures > 500 °C). [9] Inspired by reported examples for high affinity synthetic hosts [10] and our earlier work on the binding of polycyclic aromatic hydrocarbons by expanded πreceptors [11,12] we hypothesized that such electron-deficient π-receptors should be able to dissolve also monomeric unsubstituted Pc compounds into solution phase. [10] Here we show that C 64 nanographene tetraimide 1 can bind unsubstituted Pcs and MPcs and keep them dissolved in organic solvents by supramolecular host-guest interactions.…”

A High‐Affinity “Synthavidin” Receptor for Squaraine Dyes

“…A major theme of modern supramolecular chemistry is the development of synthetic receptors that bind complementary guests in aqueous environments with very high affinities. [1] Inspiration is taken from the natural binding pairs avidinbiotin and streptavidin-biotin, for which association constants of the order of 10 15 M À 1 have been measured. [2] In addition to the theoretical interest, and the challenge, posed by such numbers, the (strept)avidin-biotin pairs have valuable applications in biochemistry, medicine and nanotechnology.…”