Biomimetic Hydrogen‐Bonded G ⋅ C ⋅ G ⋅ C Quadruplex within a Tetraphenylethene‐Based Octacationic Spirobicycle in Water
Lingyu Zhao, Lin Cheng, Yanxia Yang, Pingxia Wang, Ping Tian, Ting Yang, Hao Nian, Liping Cao
Abstract
Abstract In biological systems, nucleotide quadruplexes (such as G‐quadruplexes) in DNA and RNA that are held together by multiple hydrogen bonds play a crucial functional role. The biomimetic formation of these hydrogen‐bonded quadruplexes captured by artificial systems in water poses a significant challenge but can offer valuable insights into these complex functional structures. Herein, we report the formation of biomimetic hydrogen‐bonded G ⋅ C ⋅ G ⋅ C quadruplex captured by a tetraphenylethene (TPE) based octacationic spirobicycle ( 1 ). The spirobicyclic compound possesses a three‐dimensional (3D) crossing dual‐cavity structure, which enables the encapsulation of four d(GpC) dinucleotide molecules, thereby realizing 1 : 4 host–guest complexation in water. The X‐ray structure reveals that four d(GpC) molecules further form a two‐layer G ⋅ C ⋅ G ⋅ C quadruplex with Watson–Crick hydrogen bonds, which are stabilized within the dual hydrophobic cavities of 1 through the cooperative non‐covalent interactions of hydrogen bonds, CH⋅⋅⋅π interactions, and hydrophobic effect. Due to the dynamically‐rotational propeller chirality of TPE units, 1 with adaptive chirality can further serve as a chiroptical sensor to exhibit opposite Cotton effects with mirror‐image CD spectra for the pH‐dependent hydrogen‐bonded assemblies of d(GpC) including the Watson–Crick G ⋅ C ⋅ G ⋅ C (pH 9.22) and Hoogsteen G ⋅ C + ⋅ G ⋅ C + (pH 5.74) quartets through the host–guest chirality transfer in water.