Light‐triggered substituted azobenzene‐based molecular switches are well known for their potential applications as molecular machines. The Z‐isomer stability affected by heteroaromatic groups, extended aromaticity, different substituents, and varying the solvents based on their polarity. In this regards, five different anthraquinone/imidazole‐based azobenzene derivatives have been synthesized with different electronic push/pull substituents. The detailed study of photoswitching processes with kinetic data was appraised by using UV/Vis and 1H‐NMR spectroscopic techniques. The investigation of light‐induced hydroxyl group conversion to quinone‐hydrazone tautomerization has been observed during the isomerization. Most importantly, intermolecular hydrogen bonding interaction between tautomeric form and a higher polar solvent (DMSO) block the isomerization, but in a less polar solvent (DCM), light‐induced trans ↔ cis isomerization takes place by tautomerization pathway with well‐separated π→π* and n→π* transitions. Further, the detailed mechanistic study of solvent‐assisted light‐induced tautomerization with the role of hydrogen bonding and the following WRITE‐READ‐ERASE‐READ system have been derived by using molecular logic gates.

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A new tris-heteroleptic complex [Ru(bpy)(dppz)(OSO)](ClO), [1](ClO) (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine and OSO = 2-methylsulfinylbenzoate), was synthesized and characterized to control the photochromic Ru-S → Ru-O linkage isomerization. Details isomerization kinetics studied by UV-visible absorption spectroscopy and cyclic voltammetry revealed that efficient photochromic S → O isomerization and thermal O → S reversal take place in solvents like propylene carbonate (PC), methanol, and dichloromethane. Strikingly, photoisomerization of [1](ClO) is arrested in water although is active in the analogous compound [Ru(bpy)(OSO)](ClO). Effective excited state deactivation through dark MLCT state involving dppz ligand of [1](ClO) switches off photochromism in aqueous medium. Interestingly, the photochromism is activated in aqueous solution in the presence of DNA which shields the dppz localized dark state through intercalation. Ultrafast transient absorption spectroscopic measurement sheds light on the differential behavior of photochromism in aqueous and nonaqueous solvents.