Structural dynamics of photoswitchable solids – Strudyn
Structural dynamics of photoswitchable solids
The aim of the project is to study the molecular mechanisms behind photo-induced phenomena in functional materials. To this end, methods for characterizing the structure and dynamics of materials are being developed and implemented.
Photoisomerisation mechanism
The structure of metal-nitrosyl complexes can be modified by light [1]. These light-induced structures correspond to linkage isomers of the nitrosyl ligand (designated GS for “Ground state” and MS1 and MS2 for “Metastable state” 1 and 2) and their formation is accompanied by photochromic and photorefractive effects, making these materials interesting for optical applications [2]. The main objective of the project is a detailed study of this photo-induced isomerization in solid-state ruthenium nitrosyl complexes in order to understand the underlying mechanism, in particular the population sequences between GS, MS1 and MS2, to explore the potential energy surface and identify all the metastable states and their properties, and to establish principles for selectively orienting the system towards one or other structural configuration. [1] P. Coppens, I. Novozhilova, A. Kovalevsky, Chem. Rev. 102, 861–884 (2002). Photoinduced Linkage Isomers of Transition-Metal Nitrosyl Compounds and Related Complexes. https://doi.org/10.1021/cr000031c [2] D. Schaniel, M. Imlau, T. Weisemoeller, T. Woike, K. W. Krämer, H.-U. Güdel, Adv. Mater. 19, 723–726 (2007). Photoinduced Nitrosyl Linkage Isomers Uncover a Variety of Unconventional Photorefractive Media. https://doi.org/10.1002/adma.200601378
The aim is to establish the structure-property relationship and photoisomerization mechanism(s) of solid-phase ruthenium nitrosyl complexes as a function of temperature, irradiation type (pulsed/continuous) and irradiation wavelength.
Photocrystallography uses a combination of scattering/diffraction methods and spectroscopy under light irradiation to elucidate the structure-properties relationship of functional materials.
We have been able to demonstrate by static photocrystallography [1] that the MS1 state is generated via the MS2 state: by combining in-situ absorption measurements during X-ray diffraction measurements, under irradiation with continuous or pulsed LASERs, with infrared spectroscopy measurements under irradiation with pulsed LASERs, we have unveiled the photoisomerization mechanism in ruthenium-nitrosyl complexes through the example of [Ru(py)4FNO](ClO4)2 . In addition to this main result, we have established some principles concerning the (relative) stability of the MS1 and MS2 states. Stability (measured via the decay temperature Td) increases linearly with the electronegativity of the ligand in the trans-to-NO position, or the Hirshfeld charges, if intermolecular interactions can be neglected. In the case of significant intermolecular interactions, the effect on MS1 and MS2 is different, in particular MS2 is more sensitive and its stability can therefore be increased via this bias, e.g. by changing the counter ions [2-4].
[1] A. Hasil et al., ChemPhotoChem, 2024, 8 (3), (10.1002/cptc.202300149). (hal-04568693)
[2] A. Mikhailov et al.. New Journal of Chemistry, 2023, 47 (33), pp.15506-15513. (10.1039/D3NJ02696E). (hal-04187656)
[3] A. Mikhailov et al., New Journal of Chemistry, 2022, 46 (26), pp.12641-12650. (10.1039/D2NJ01388F). (hal-03826183)
[4] Artem Mikhailov, et al. Dalton Transactions, 2023, 52 (4), pp.919-927. (10.1039/D2DT03497B). (hal-03960413)
Demonstration of the two-step MS1 generation mechanism has highlighted our method of combining in-situ absorption/DRX with infrared spectroscopy under pulsed LASER irradiation. This method can be applied to other types of photo-induced processes to study the mechanisms of photo-isomerization or photo-induced phase transition.
The objective of the project is a detailed study of the photoinduced isomerization of ruthenium nitrosyl complexes in the solid state in order to understand the underlying mechanism, explore the potential energy surface and identify all metastable states and their properties, and establish the principles allowing for selectively driving the system towards one or the other structural configuration. The original feature of the project is the determination of the structure of possible intermediate states during photoisomerisation by time-resolved X-ray diffraction on the millisecond time scale. For this purpose, the two partners will join their complementary expertise. The Russian partner brings in the knowledge about the synthesis and characterisation of ruthenium nitrosyl complexes with the trans-coordinate NO-Ru-F. These complexes are particularly suited for the study, since they have the highest thermal stability of linkage isomers, which makes it possible to study isomerization reactions in a wide temperature range. The French partner brings in its expertise in photocrystallography and especially the unique laboratory X-ray diffractometer allowing for collecting diffraction data after pulsed LASER excitation with millisecond time resolution.
Project coordination
Dominik Schaniel (Cristallographie, résonance magnétique et modélisations)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partnership
CRM2 Cristallographie, résonance magnétique et modélisations
NIIC Nikolaev Institute of Inorganic Chemistry / Laboratory of rare platinum metal chemistry
Help of the ANR 177,520 euros
Beginning and duration of the scientific project:
January 2022
- 36 Months
