Biomimetic Hydrogen‐Bonded Base Pairing of Nucleoside Triphosphates in Water by a Tetraphenylethene‐Based Octaimidazolium Cage

Studying biomimetic hydrogen-bonded (H-bonded) base pairing of nucleoside triphosphates (NTPs) in aqueous solutions using artificial recognition systems can enhance our understanding of the principles of base pairing in natural systems. Here, we report a water-soluble tetraphenylethene-based octaimidazolium cage (1) as an artificial host, which promotes the biomimetic H-bonded base pairing of NTPs in water by forming their 1:1:1 hetero-ternary or 1:2 homo-ternary host-guest complexes. Both the matched and mismatched H-bonded base pairs of NTPs are stably captured within the cavity of 1 through the multiple noncovalent interactions of hydrogen bonds, CH⋯π/π⋯π interactions, electrostatic forces, and hydrophobic effect. ITC studies reveal the aqueous biomimetic recognition of 1 for these base pairs is dominantly driven by either classical (entropy-driven, ΔS ≥ 0) or non-classical (enthalpy-driven, ΔH ≪ 0) hydrophobic effects. The X-ray structure of the 1•GTP₂ complex shows an unprecedented base pair (G:G*) with Watson-Crick H-bonded pattern, resulting from the prototropic tautomerism of normal guanine (G) to tautomeric guanine (G*). Through adaptive host-guest chirality transfer, 1 can also act as a chiroptical sensor, exhibiting differentiated circular dichroism (CD) for these base pairs and enabling dynamic CD inversion to monitor the pH-dependent transformation of GTP base pairs.