Stabilization and Multiple-Responsive Recognition of Natural Base Pairs in Water by a Cationic Cage

The hydrogen-bonded(H-bonded)base pairs,double H-bonded A•T and triple H-bonded G•C in DNA,are important units for storing,encoding,and expressing genetic information.Owing to the interference from water,however,the formation of H-bonded base pairs from short deoxynucleotide fragments such as mono-or di-deoxynucleotide are not easily achieved in aqueous solutions.

On-off-on fluorescence detection for biomolecules by a fluorescent cage through host-guest complexation in water

Detection of nucleoside derivatives has paramount importance because they are the essential biomolec-ular units for all life.Herein,we report a host-guest approach by using a fluorescent tetraphenylethene-based octacationic cage as host and 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt(HPTS)as guest and fluorescent indicator to form non-fluorescent 1:1:1 host-(endo-exo)guest complex in water.This new host-(endo-exo)guest complex can be successfully used for detecting nucleosides(e.g.,ATP and GTP),DNA(e.g.,sm-DNA),and antibiotics(e.g.,Penicillin G)with off-on fluorescence response via a competitive host-guest exchange with HPTS as exo-guest in water.Furthermore,this on-off-on fluorescent host-guest com-plex is also used for cell imaging based on ATP concentration in HeLa cells.Therefore,this study not only provides insight into the construction of a supramolecular probe with on-off-on fluorescence via host-guest complexation and exchange in solution,but also realizes a universal method for detecting and monitoring biomolecules.

Adaptive Chirality of an Achiral Cage:Chirality Transfer,Induction,and Circularly Polarized Luminescence through Aqueous Host-Guest Complexation

Chirality transfer,induction,and circularly polarized luminescence(CPL)using supramolecular hosts,such as macrocycles and cages,have been explored for wide-ranging applicationsin chiral recognition,sensing,catalysis,and chiroptical functional materials.Herein,we report the adaptive chirality of an achiral tetraphenylethene(TPE)-basedoctacationic cage(1)inducedby bindingwith enantiopure deoxynucleotides(A,T,C,and G)throughhost-guest(H-G)complexationinwater.The hydrophobic cavity of the cage efficiently stabilizes the hydrogen-bonded dimerization of deoxynucleotides(A_(2),T_(2),C_(2),and G_(2))to form H-G complexes in 1∶2 ratios.Given the photophysical properties and dynamic rotational conformation of the TPE units of the cage,cage⊃deoxynucleotide complexes exhibited excellent chiroptical propertiesbased on chirality transfer andinduction from the chiral guest to the achiral host.For this supramolecular system,the cage showed a unique adaptive chirality of the double clockwise-typed(PP)rotational conformation of the two TPE units,which was induced by chiral guests(e.g.,A_(2),T_(2),C_(2),and G_(2))through H-G complexation in water.Furthermore,the adaptive chirality of the cage⊃deoxynucleotide complexes successfully induced CPL signals in homogeneous aqueous solutions.This study provides insights for the construction of adaptive chirality from an achiral TPE-based octacationic cage with dynamic conformational nature,and might facilitate further design of chiral functional materials for several applications,such as chiral recognition,sensing,displays,catalysis,and other chiral fluorescent supramolecular systems based on aqueous H-G complexation.