Abstract
Developing new photoswitchable noncovalent interaction motifs with controllable bonding affinity is crucial for the construction of photoresponsive supramolecular systems and materials. Here we describe a unique “photolocking” strategy for realizing photoswitchable control of quadruple hydrogen-bonding interactions on the basis of modifying the ureidopyrimidinone (UPy) module with an ortho-ester substituted azobenzene unit as the “photo-lock”. Upon light irradiation, the obtained Azo-UPy motif is capable of unlocking/locking the partial H-bonding sites of the UPy unit, leading to photoswitching between homo- and heteroquadruple hydrogen-bonded dimers, which has been further applied for the fabrication of novel tunable hydrogen bonded supramolecular systems. This “photolocking” strategy appears to be broadly applicable in the rational design and construction of other H-bonding motifs with sufficiently photoswitchable noncovalent interactions.
Highlights
Hydrogen bonding is ubiquitously adopted by nature to form complex structures and implement delicate functions, as exempli ed by DNA and proteins
Model compounds 1a–1d (Table 1) were rst designed and prepared to test the practicability of the “photolocking” strategy. Their UV-vis absorption spectra were recorded under irradiation with light sources of different wavelengths (Fig. S1†), according to which the optimal irradiation wavelengths could be determined when the contents of their E- or Z-isomers in the solution reached the maximum at the photostationary stationary state (PSS) (Table 1)
These results clearly demonstrated that the design strategy of introducing the orthoester-substituted azobenzene for photoswitching could achieve photocontrolled breakage/recovery of the intramolecular Hbonding in compound 1 (Table 1)
Summary
Hydrogen bonding is ubiquitously adopted by nature to form complex structures and implement delicate functions, as exempli ed by DNA and proteins. A er irradiation with UV light (365 nm), two individually diffused entities were observed from the resulting PSSZ mixtures of Azo-UPy with the diffusion coefficients of D1 1⁄4 4.57 Â 10À10 m2 sÀ1 and D2 1⁄4 6.31 Â 10À10 m2 sÀ1 (Fig. S28†), which could be assigned to the formed quadruple H-bonded (Z-Azo-UPy)[2] dimer and the E-Azo-UPy monomer, respectively.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call