A new class of photoactive and chelating ligands L1-3 have been designed and synthesized by incorporating arylazo-3,5-dimethylpyrazole units in the ligand frameworks. Significantly they are designed in such a way...

reversible erasing and printing with light makes these molecules useful in such applications.

Light‐responsive molecular systems with multiple photoswitches in C3‐symmetric designs have enormous application potential. The design part of such molecular systems is critical due to its influence in several properties associated with the photoswitches. In order to tune, and in the evaluation of the design–property relationship, we synthesized 18 tripodal systems with variations in the core, linkers, connectivity, and azo(hetero)arene photoswitches. Through extensive spectroscopic and computational studies, we envisaged the factors controlling near‐quantitative photoisomerization in both the directions (bistability) and the thermal stability of the metastable states. Furthermore, we also evaluated the impact of designs in obtaining reversible photo‐responsive sol‐gel phase transitions, solvatochromism, photo‐ and thermochromism.

We report the design, synthesis, characterization, and photochemistry of three photoresponsive azoheteroarene‐based neutral N‐donor ligands. Furthermore, those bidentate and tridentate ligands have been coordinated with Cu(I) and Cu(II) metal ions to form seven complexes exhibiting different geometries and nuclearities. Detailed studies of the electronic properties, photoswitching, and thermal reverse isomerization behavior of the photoswitched states of the free ligands and their metal complexes in different solvents are presented.

In the recent decades, the investigations on photoresponsive molecular systems with multiple azoarenes are quite popular in diverse perspectives ranging from fundamental understanding of multiple photoswitches, supramolecular chemistry, and various application prospects. In fact, several insightful and conceptual designs of such systems were investigated with architectural distinctions. In particular, the demonstration of applications such as data storage with the help of multistate or orthogonal photoswitches, light modulation of catalysis via cooperative switching, sensors using supramolecular host-guest interactions, and materials such as liquid crystals, grating, actuators, etc. are some of the milestones in this area. Herein, we cover the recent advancements in the research areas of multiazoarenes containing systems that have been classified into Type-1 {linear, non-linear, and core-based (A)}, Type-2 {tripodal C 3symmetric (C3)} and Type-3 {macrocyclic (M)} structural motifs.

We report a new class of arylazopyrazolium-based ionic photoswitches (AAPIPs). These AAPIPs with different counter ions have been accessed through a modular synthetic approach in high yields. More importantly, the AAPIPs exhibit excellent reversible photoswitching and exceptional thermal stability in water. The effects of solvents, counter ions, substitutions, concentration, pH, and glutathione (GSH) have been evaluated using spectroscopic investigations. The results revealed that the bistability of studied AAPIPs is robust and near quantitative. The thermal half-life of Z isomers is extremely high in water (up to years), and it can be lowered electronically by the electron-withdrawing groups or highly basic pH.

Azoheteroarenes are emerging classes of photoswitches with versatile scaffolds that offer distinct features such as efficient photoisomerization, tunable stability of the photoswitched states, and bidirectional photoswitching. Moreover, the heteroatoms of such photoswitches exhibit coordination ability to bind to the metal centers. The resulting azoheteroarene‐based metal complexes can be designed and developed to tune various metal‐based properties towards intriguing applications such as in optics, magnetic properties, data storage applications, and catalysis. Despite the diverse utility of azopyridines in such contexts, other azoheteroarenes, particularly the state‐of‐the‐art five‐membered heterocycle‐based photoswitches, remain under‐explored. In this Review, we describe the diverse classes of azoheteroarene‐coordinated metal complexes reported in the literature and survey their photoswitching behaviour and applications. Furthermore, we identify potential azoheteroarene candidates for building photochrome‐coupled metal complexes and supramolecular architectures for maximizing the photo‐tuning of metal‐related properties.

A modular approach has been adopted to synthesize a wide range of visible light-driven photoswitchable azoheteroarenes. In this regard, we considered ortho substitution of cyclic amines in the aryl ring and varied substitution patterns. Using detailed spectroscopic studies, we established a relationship between structure and photoswitching ability and also half-lives of the Z-isomers. Through this, we envision tunable and bidirectional longer wavelength photoswitches.