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Exploring new noncovalent bonding motifs with reversibly tunable binding affinity is of fundamental importance in manipulating the properties and functions of supramolecular self‐assembly systems and materials. Herein, for the first time, we demonstrate a unique visible‐light‐switchable telluro‐triazole/triazolium‐based chalcogen bonding (ChB) system in which the Te moieties are connected by azobenzene cores. The binding strengths between these azo‐derived ChB receptors and the halide anions (Cl−, Br−) could be reversibly regulated upon irradiation by visible light of different wavelengths. The cis‐bidentate ChB receptors exhibit enhanced halide anion binding ability compared to the trans‐monodentate receptors. In particular, the telluro‐triazolium‐based ChB receptor can achieve both high and significantly photoswitchable binding affinities for halide anions, which enable it to serve as an efficient photocontrolled organocatalyst for ChB‐assisted halide abstraction in a Friedel–Crafts alkylation benchmark reaction. [ABSTRACT FROM AUTHOR]

A photo‐switchable hetero‐complementary quadruple H‐bonding array, which consists of an azobenzene‐derived ureidopyrimidinone (UPy) module (Azo‐UPy) and a nonphotoactive diamidonaphthyridine (DAN) derivative (Napy‐1), is constructed based on a reversible photo‐locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo‐switchable quadruple H‐bonded dimerization between Azo‐UPy and Napy‐1 can be achieved with exhibiting 4.8×104‐fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo‐controlled macroscopic self‐assembly behavior can be fabricated by introducing such quadruple H‐bonding array as photo‐regulable noncovalent interfacial connections. [ABSTRACT FROM AUTHOR]

Exploring dynamic bonds and their applications in fabricating dynamic materials has received great attention. A photoinduced [2]rotaxane-based dynamic mechanical bond (DMB) features visible-light-triggered dynamic bonding behavior that is essentially distinguished from conventional dynamic chemical bonds. In this DMB, a photoisomerizable ortho-fluoroazobenzene unit is introduced as a steric-controllable stopper, the visible-light-induced dynamic wagging movement of which enables the photoregulated threading of the macrocycle. This allows reversible in situ de-/reforming of the mechanical bond without involving dynamic chemical linkage. The DMB-cross-linked polymeric gel shows interesting photoinduced degradation behavior upon visible light irradiation. Benefiting from the distinctive dual dynamic nature of reversible bonding behavior and mechanical interlocked structure, this DMB is expected to serve as a new type of dynamic bond that can be applied in designing dynamic soft materials., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)