New method enables control of azobenzenes with visible light, opening up new applications

Azobenzenes possess remarkable versatility, with potential applications ranging from miniature machinery to technological advancements and light-sensitive pharmaceuticals. These molecules can switch between two distinct forms when exposed to light, but their equilibrium mixture has hindered optimal use in various applications.

A groundbreaking approach, known as “disequilibration by sensitization under confinement” or DESC, is changing the game. Collaborative research led by Professors Igor Schapiro from Hebrew University of Jerusalem, Rafal Klajn from the Weizmann Institute of Science, Arri Priimagi from Tampere University, and their team, has introduced this novel concept. It offers the unprecedented ability to trigger a specific molecular transformation, particularly the conversion from the “E” to the “Z” state, akin to turning a switch “on” and “off” in applications. What sets this apart is that it can be activated by visible light, including the red spectrum.

The new mechanism is based on the supramolecular approach where a molecular switch (azobenzene) and a photosensitizer are confined in a molecular cage. The confined space of the cage fits only an E-form of azobenzene but not the Z-form of azobenzene, which is expulsed from the cage. Credit: Jonathan R. Church

The study, titled “Disequilibrating azobenzenes by visible-light sensitization under confinement,” has been published in the journal Science.

Azobenzenes stand out due to their capacity to change shape in response to various types of light, including ultraviolet and visible light. This phenomenon, known as photoisomerization, enables azobenzenes to transition between two distinct shapes or isomers, denoted as “E” and “Z.” This unique property has far-reaching implications, driving advancements in nanotechnology, data storage, drug delivery, materials science, and biological research.

In essence, azobenzenes play a pivotal role in numerous scientific and technological breakthroughs.

Prof. Igor Schapiro of Hebrew University of Jerusalem stated, “Through our computational studies and quantum chemical calculations, we have unveiled an innovative approach that not only advances the fundamental understanding of azobenzene but also opens doors to practical applications. These applications harness the power of visible light, including the red spectrum.”

Azobenzenes are central components in a wide array of technologies, spanning molecular switches, actuators, data storage, and drug delivery systems. Until now, their photoisomerization required ultraviolet light, limiting their applicability. However, DESC marks a significant milestone by offering a supramolecular approach that enables controlled E-to-Z isomerization using harmless light.

This pioneering research unlocks exciting prospects for employing azobenzenes across diverse fields. By expanding the range of light wavelengths that can induce isomerization, DESC holds the potential to boost the efficiency and versatility of azobenzene-based technologies.

Source: Hebrew University of Jerusalem

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