Ultra‐Tight Host‐Guest Binding with Exceptionally Strong Positive Cooperativity

Abstract

Cooperativity plays a critical role in selfassembly and molecular recognition. A rigid aromatic oligoamide macrocycle with a cyclodirectional backbone binds with DABCO-based cationic guests in a 2 : 1 ratio in high affinities (K total � 10 13 M À 2 ) in the highly polar DMF. The host-guest binding also exhibits exceptionally strong positive cooperativity quantified by interaction factors α that are among the largest for synthetic hostguest systems. The unusually strong positive cooperativity, revealed by isothermal titration calorimetry (ITC) and fully corroborated by mass spectrometry, NMR and computational studies, is driven by guest-induced stacking of the macrocycles and stabilization from the alkyl end chains of the guests, interactions that appear upon binding the second macrocycle. With its tight binding driven by extraordinary positive cooperativity, this hostguest system provides a tunable platform for studying molecular interactions and for constructing stable supramolecular assemblies.

Strategic Insertion of Heavy Atom to Tailor TADF OLED Material for the Development of Type I Photosensitizing Catalytic Red Emissive Assemblies

“…Upon addition of 5 % D 2 O in DMSO-d 6 :CDCl 3 (9.5:0.5), the aromatic signals get broadened and are shifted upfield due to the enhanced π-π intermolecular stacking of aromatic moieties (Figure S10). [32][33] The powder X-ray diffraction (XRD) studies also support the existence of intermolecular π-π stacking in DPZ-PHZ molecules (Figure S11). [34][35] To have an idea about morphology, we carried out scanning electron microscopy (SEM) studies.…”

“…To understand the driving force for the aggregation of DPZ‐PHZ molecules, we carried out the 1 H NMR studies in DMSO‐ d 6 :CDCl 3 :D 2 O. Upon addition of 5 % D 2 O in DMSO‐ d 6 :CDCl 3 (9.5:0.5), the aromatic signals get broadened and are shifted upfield due to the enhanced π–π intermolecular stacking of aromatic moieties (Figure S10) [32–33] . The powder X‐ray diffraction (XRD) studies also support the existence of intermolecular π–π stacking in DPZ‐PHZ molecules (Figure S11) [34–35] …”

Construction of Oligorotaxanes with Hydrogen‐Bonded Aramide Macrocycles through Threaded Host‐Guest Complexation

“…Gong and colleagues reported a novel exteriorly H‐bonded macrocycle 5 a with a C 3 symmetry, which can bind bipyridinium guest G7 and DABCO‐based cationic guests G8 – G10 to form a highly stable pseudo[3]rotaxane in 2 : 1 stoichiometry (Figure 9). [53] The isothermal titration calorimetry (ITC) experiments demonstrated high binding affinities ( K total =3.2×10 13 M −2 for 4a 2 ⊃ G9 ; K total =2.0×10 13 M −2 for 4a 2 ⊃ G10 in DMF) for DABCO‐based cationic guests and strong positive cooperativity (α=2700 for 4a 2 ⊃ G9 , α=5500 for 4a 2 ⊃ G10 ) of host‐guest binding systems. This result contrasts with the negative to weakly positive cooperativity observed for macrocycle 1 a with bipyridinium guests (cooperativity factor α ranging from 0.12 to 2.51).…”

Enzymatic Activation and Continuous Electrochemical Production of Methane from Dilute CO2 Sources with a Self-Healing Capsule

“…The addition of an equivalent mole ratio of carbon dioxide adduct (2-hydroxyethyl) carbamic acid (donated as 1-CO 2 ), which was formed by directly bubbling CO 2 gas into a DMSO solution containing monoethanolamine 1, demonstrated a new peak at m/z = 1667.8485 that was assigned to the species of [1-CO 2 •H1] 2+ via a comparison with the simulation results based on the natural isotopic abundances (Figure 1c), referring to the stability of the host and the host−guest complex in the solution. 21 H1 exhibited a single set of ligand signals in 1 H NMR, the addition of 1-CO 2 adduct shifted the −OH proton and the −CH 2 protons downfield 22 (Figure S7). Diffusion-ordered 1 H NMR spectra of H1 and of H1 with that of 1-CO 2 (Figure 2a) demonstrated the almost identical diffusion coefficient, 7.90 × 10 −11 m 2 •S −1 .…”