Ternary molecular switching in a single-crystal optical actuator with correlated crystal strain.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39934164.
- Also identified by DOI 10.1038/s41467-025-56795-w and PMC identifier 11814404.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
A growing portfolio of single-crystal optical actuators is forging a new class of photonic materials that hold prospects for quantum technologies. Ruthenium-based complexes that exhibit this phenomenon via SO<sub>2</sub>-linkage photoisomerisation are of particular interest since they display multiple metastable states, once induced by green light; yet, complete photoconversion into each SO<sub>2</sub>-isomeric state is rarely achieved. We discover a new complex, trans-[Ru(SO<sub>2</sub>)(NH<sub>3</sub>)<sub>4</sub>(4-bromopyridine)]tosylate<sub>2</sub>, that produces 100% photoconverted η<sup>1</sup>-OSO isomeric crystal structures at 90 K, which fully transition into η<sup>2</sup>-(OS)O photoisomers upon warming to 100 K, while the dark-state η<sup>1</sup>-SO<sub>2</sub> structure is wholly recovered by heating the crystal to room temperature. Crystal structures and optical-absorption profiles of each state are captured via in-situ light-induced single-crystal X-ray diffraction and optical-absorption spectroscopy. Results show that both photoisomeric species behave as optical switches, but with distinct optical properties. The photoisomerisation process causes thermally-reversible micro- and nanoscopic crystal strain, as characterised by optical microscopy and in-situ light-induced atomic-force microscopy.