A photoresponsive palladium complex of an azopyridyl-triazole ligand: light-controlled solubility drives catalytic activity in the Suzuki coupling reaction.

Attila Kunfi,Tamás Gazdag,Gábor London,Krisztina Németh,Tamás Holczbauer,Péter J Mayer,István Jablonkai,Péter Pál Kalapos

doi:10.1039/d1ra03838a

Attila Kunfi, Tamás Gazdag + Show 6 more

Open Access

https://doi.org/10.1039/d1ra03838a

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Abstract

Herein, the design and synthesis of a click-derived Pd-complex merged with a photoswitchable azobenzene unit is presented. While in the trans-form of the switch the complex showed limited solubility, the photogenerated cis-form rendered the molecule soluble in polar solvents. This light-controllable solubility was exploited to affect the catalytic activity in the Suzuki coupling reaction. The effect of the substrate and catalyst concentration and light intensity on the proceeding and outcome of the reaction was studied. Dehalogenation of the aryl iodide starting material was found to be a major side reaction; however, its occurrence was dependent on the applied light intensity.

Highlights

The combination of light-responsive molecular machines with catalytic transformations led to the rapidly developing eld of photoswitchable catalysis.[1,2,3,4] Modulating the catalytic activity with light as an input signal can impact the development of catalysis in different ways
While in the trans-form of the switch the complex showed limited solubility, the photogenerated cis-form rendered the molecule soluble in polar solvents. This lightcontrollable solubility was exploited to affect the catalytic activity in the Suzuki coupling reaction
We explored the design of an organometallic catalyst having photoswitchable solubility and its applicability and limitations in the Suzuki coupling reaction

Summary

Introduction

The combination of light-responsive molecular machines with catalytic transformations led to the rapidly developing eld of photoswitchable catalysis.[1,2,3,4] Modulating the catalytic activity with light as an input signal can impact the development of catalysis in different ways. Controlling the occurrence of chemical transformations temporally and spatially in molecular systems that approach cellular complexity can be foreseen. The light-induced actuation of different forms of the same catalyst will help us to integrate the aims of green chemistry[5] such as activity, selectivity and recycling, within a single system through controlled structural changes.[6] The remarkable progress that has been made in the eld of lightdriven molecular machines provides a variety of established photochromes to serve as control units.[7] Among these, azobenzenes, dithienylethenes and overcrowded alkenes are the most frequently exploited units in photoswitchable catalysis. Within the vast set of molecular catalysts, organometallic

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