PHOTOCAT

Photoinduced Catalysis in a Nanoparticle System

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 Obiettivo del progetto (Objective)

'Metal nanoparticles (NPs) have been studied intensely in the last decade due to their novel optical, catalytic and electronic properties. Because of the nanoscopic size of NPs, self-assembly has been by far the most important means of generating higher-order architectures. Light is a particularly attractive means to self-assemble of NPs because it can be delivered instantaneously and into a precise location. In order to render NPs photoactive, their surfaces need to be functionalized with photoresponsive ligands. As an incoming Independent Researcher at the Weizmann Institute of Science, the Applicant wishes to develop new nanomaterials resulting from this marriage of nanoscience and organic chemistry. The Applicant has extensive experience in the fields of nanoscience and organic chemistry, acquired during the last several years at Northwestern University, USA. In the proposed project, he would like to develop a NP-based system, in which catalysis is regulated by light. This system takes advantage of his previous research, which has shown that NPs can be reversibly assembled and disassembled using light (PNAS 2007, 104, 10305; Science 2007, 316, 261). For NPs decorated with mixed monolayers comprising photoswitches and molecular catalysts, disassembly of such aggregates will result in a drastic increase of a catalytic surface area exposed to the solvent, and therefore in effective catalysis of a model reaction. As a result, self-assembly process will be transduced into catalytic activity. The system will then be extended to include various types of NPs functionalized with mixtures of different photoswitches and catalysts. These NPs will assemble / disassemble when exposed to different wavelengths of light. The ultimate goal of the project is to demonstrate that in a complex mixture of mutually incompatible chemicals, reactions can be turned 'on' and 'off' using light of different wavelengths, in a way similar to enzymatic regulation of reactions in living cells.'

Introduzione (Teaser)

Researchers have developed metallic nanoparticles that self-assemble into catalytic structures when exposed to specific wavelengths of light.

Descrizione progetto (Article)

Nanoparticle science has advanced rapidly over the last decade, with self-assembly being the most efficient way of creating larger structures from nanoparticles.

Recent work has also shown that light can be used to signal assembly or disassembly of nanoparticles.The EU-funded 'Photoinduced catalysis in a nanoparticle system' (PHOTOCAT) project aimed to create a nanoparticle system that assembles into a catalytic matrix when exposed to light.

The project developed two different self-assembling nanoparticle systems: a so-called 'nanobowl' structure, and a 3D nanoparticle matrix.A bowl-shaped metallic nanoparticle aggregate, the nanobowl can be adjusted to hold various nano-scale objects and chemicals.

Researchers attached photo-responsive molecules to the interior surface of the nanobowl, which bind specific molecules or enzymes when exposed to light.

The second system is made up of metallic nanoparticles with light-activated 'switches'.

When exposed to ultraviolet light, these nanoparticles aggregate to form a regular crystalline matrix structure with spaces called nanopores.

PHOTOCAT showed that these pores function as reaction chambers, where the reaction between small molecules in the solution is significantly sped up.

The system could also be disassembled and reassembled repeatedly.

These systems offer huge potential for precise control of chemical reactions using light waves.

PHOTOCAT has thus advanced the state of the art in nanoparticle chemistry.