Efficient Sensitized Z→E Photoisomerization of an Iridium(III)‐Azobenzene Complex over a Wide Concentration Range

Abstract

To improve the sensitized Z→E photoisomerization of azobenzenes, and circumvent the threshold concentration necessary for the bimolecular photoinduced electron transfer reaction to generate the rapidly isomerizing Z-azobenzene radical anion, an Ir complex with a covalently tethered azobenzene fragment was synthesized. Selective irradiation of the MLCT band of the Ir complex induced an efficiently sensitized photoswitching of the dyad over a wide concentration range and even at high dilution.

Structure-switching M3L2 Ir(iii) coordination cages with photo-isomerising azo-aromatic linkers

“…The pattern of spectral changes we observe are very similar to those observed by Hecht et al for a mononuclear [Ir(C^N) 2 (acac-AZB)] complex which showed photo-isomerisation to a photostationary state containing 46% Z -isomer. 33 Mononuclear [Ir(C^N) 2 (NN) n ] + complexes with AZB-decorated ligands have been reported to have greatly reduced or even entirely suppressed E → Z photo switching due to low energy MLCT bands, which provide a pathway for relaxation of the π* azo excited state, but these studies featured very little reduction of the π → π* band on irradiation. 28 This is clearly not the case here ( Fig.…”

Configurational Selection in Azobenzene‐Based Supramolecular Systems Through Dual‐Stimuli Processes

“…Beside the works describing the complexation with alkaline cations, a large number of studies also demonstrated that transition metals such as palladium, zinc, iron, nickel, copper, iridium, etc may strongly perturb the photoisomerization equilibrium of the azobenzene switch . The transition metal ion can directly bind to the nitrogen atoms of the N=N bond or to a dedicated functional group connected to the azobenzene moiety, and it may influence the switching process with different mechanisms.…”

“…Given the large body of literature on this topic, in this review we will limit our discussion only to those examples that are pertinent to the focus of this review. The interested reader is addressed to the comprehensive reviews on the topic …”

Demonstration of an azobenzene derivative based solar thermal energy storage system

“…This, unfortunately, showed a strong photo-stationary effect between AZOcis and AZO-trans, therefore highlights the need to further develop the azobenzene system by altering the optical properties. [51][52][53] Further improvement to increase quantum yields and diminish the absorption of photoisomer, as well as differentiate the spectral difference between cis and trans states, would be certainly required. To estimate the theoretical heat release temperature difference, a corrected formula was introduced to account for the change from the diluted solution to the neat sample.…”