Measurement of the conformational switching of azobenzenes from the macro- to attomolar scale in self-assembled 2D and 3D nanostructures

Quintano, Vanesa and diez-Cabanes, Valentin and Dell’Elce, Simone and di mario, Lorenzo and pelli cresi, stefano and paladini, alessandra and beljonne, david and Liscio, Andrea and Palermo, Vincenzo (2021) Measurement of the conformational switching of azobenzenes from the macro- to attomolar scale in self-assembled 2D and 3D nanostructures. Physical Chemistry Chemical Physics, 23. pp. 11698-11708. ISSN 1463-9076

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Abstract

It is important, but challenging, to measure the (photo)induced switching of molecules in different chemical environments, from solution through thin layers to solid bulk crystals. We compare the cis–trans conformational switching of commercial azobenzene molecules in different liquid and solid environments: polar solutions, liquid polymers, 2D nanostructures and 3D crystals. We achieve this goal by using complementary techniques: optical absorption spectroscopy, femtosecond transient absorption spectroscopy, Kelvin probe force microscopy and reflectance spectroscopy, supported by density functional theory calculations. We could observe the same molecule showing fast switching in a few picoseconds, when studied as an isolated molecule in water, or slow switching in tens of minutes, when assembled in 3D crystals. It is worth noting that we could also observe switching for small ensembles of molecules (a few attomoles), representing an intermediate case between single molecules and bulk structures. This was achieved using Kelvin probe force microscopy to monitor the change of surface potential of nanometric thin 2D islands containing ca. 106 molecules each, self-assembled on a substrate. This approach is not limited to azobenzenes, but can be used to observe molecular switching in isolated ensembles of molecules or other nano-objects and to study synergistic molecular processes at the nanoscale.

Item Type: Article
Subjects: 500 Scienze naturali e Matematica > 500.2 Scienze fisiche
500 Scienze naturali e Matematica > 530 Fisica
500 Scienze naturali e Matematica > 540 Chimica e scienze connesse
Depositing User: Vincenzo Palermo
Date Deposited: 05 Nov 2021 10:25
Last Modified: 05 Nov 2021 10:25
URI: http://eprints.bice.rm.cnr.it/id/eprint/21418

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