Francisco Thiago M, Gee William J, Shepherd Helena J, Warren Mark R, Shultz David A, Raithby Paul R, Pinheiro Carlos B
Physics Department, Federal University of Minas Gerais , Belo Horizonte, 31270-901, Brazil.
School of Physical Sciences, University of Kent , Canterbury CT2 7NZ, United Kingdom.
J Phys Chem Lett. 2017 Oct 5;8(19):4774-4778. doi: 10.1021/acs.jpclett.7b01794. Epub 2017 Sep 19.
Valence tautomeric interconversion (VTI) is a reversible process occurring in metal complexes in which an intramolecular metal-ligand electron transfer is accompanied by a change of metal ion spin state, creating two switchable electronic states (redox isomers). Herein, we describe the low-temperature, 30-100 K, single-crystal study of the [Co(diox)(4-CN-py)]·benzene complex (1) (diox = 3,5-di-t-butylsemiquinonate (SQ) and/or 3,5-di-t-butylcatecholate (Cat) radical; 4-CN-py = 4-cyano-pyridine) using hard synchrotron X-ray radiation with different intensities. We demonstrate for the first time that hard X-rays can induce VTI, and that the interconversion molar fraction is dependent on both intensity and exposure time. This in turn shows that X-rays, as a probe, might be altering the very nature of many structures under investigation at low temperatures, and consequently their properties. Our findings add new perspectives to VTI studies and might be of significant interest to the entire community investigating photoresponsive complexes.
价互变异构体相互转化（VTI）是金属配合物中发生的一个可逆过程，其中分子内金属-配体电子转移伴随着金属离子自旋态的变化，产生两种可切换的电子态（氧化还原异构体）。在此，我们描述了使用不同强度的硬同步辐射X射线对[Co(diox)(4-CN-py)]·苯配合物（1）（diox = 3,5-二叔丁基半醌（SQ）和/或3,5-二叔丁基儿茶酚（Cat）自由基；4-CN-py = 4-氰基吡啶）在30 - 100 K低温下进行的单晶研究。我们首次证明硬X射线可诱导VTI，且相互转化摩尔分数取决于强度和曝光时间。这进而表明，作为一种探针，X射线可能正在改变许多低温下正在研究的结构的本质，从而改变其性质。我们的发现为VTI研究增添了新视角，可能会引起整个研究光响应配合物的群体的极大兴趣。
