Ligand Driven, Light-Induced Spin-Crossover
Lead Research Organisation:
University of Leeds
Department Name: Sch of Chemistry
Abstract
The synthesis, and solid state chemistry and physics, of spin-crossover compounds is of great international interest at present. These are materials that can undergo a reversible change in magnetic moment upon application of heat, light or some other physical stimulus. This most commonly corresponds to a high-spin-to-low-spin d-electron transition at a transition metal centre, and so is accompanied by a colour change. Materials like these, whose colours can be reversibly and rapidly switched, have potential applications in display devices and in optical computing, among other things. We have been studying the iron chemistry of 2,6-dipyrazolylpyridines for some time. Iron(II) complex compounds of these ligands often undergo spin-crossover transitions near room temperature or under laser irradiation at low temperatures. Unusually, we can control the temperature of their temperature-induced colour change ( thermochromism ) fairly reliably, by appropriate substitution of our organic ligands. Conversely, we have recently found that substitution of the pyridine ring in our iron complexes has very little effect on their spin-crossover behaviour. That is a useful result that allows us to append other groups to our iron centres without compromising their thermochromism, giving us a route into multifunctional molecular devices. We now wish to apply our system to the phenomenon of light-driven, light-induced spin-crossover. That is, using mechanical motion at a light-sensitive group on the periphery of our molecules to drive a spin-state change at their iron centres. This idea has been demonstrated before, in a rather limited range of model systems. Although the switching achieved by this route up to now has generally been incomplete, it has the advantage of working at room temperature. Other ways of switching iron compounds using laser light are more efficient, but usually only work below -130 degrees Centigrade.We will make new versions of our iron(II) complexes containing two types of light-sensitive trigger. First, are groups that undergo cis/trans isomerisations about a double bond under UV light. Second, is a group that undergoes a reversible ring-opening reaction upon UV irradiation. Using the latter we hope to produce a light-driven conformational spin-crossover switch that works as a (poly)crystalline solid, which has not been achieved before.
Organisations
- University of Leeds (Lead Research Organisation)
- National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) (Collaboration)
- University of Manchester (Collaboration)
- University of Barcelona (Collaboration)
- Institut de Chimie de la Matière Condensée de Bordeaux (Project Partner)
People |
ORCID iD |
Malcolm Halcrow (Principal Investigator) |
Publications
Kershaw Cook L
(2015)
Spin state behavior of iron(II)/dipyrazolylpyridine complexes. New insights from crystallographic and solution measurements
in Coordination Chemistry Reviews
Kershaw Cook L
(2016)
A Unified Treatment of the Relationship Between Ligand Substituents and Spin State in a Family of Iron(II) Complexes
in Angewandte Chemie
Kershaw Cook LJ
(2016)
A Unified Treatment of the Relationship Between Ligand Substituents and Spin State in a Family of Iron(II) Complexes.
in Angewandte Chemie (International ed. in English)
Malcolm A Halcrow (Speaker)
(2010)
Multifunctional materials from iron/dipyrazolylpyridine spin-crossover switches
Mohammed R
(2012)
Synthesis of 2,6-Di(pyrazol-1-yl)pyrazine Derivatives and the Spin-State Behavior of Their Iron(II) Complexes
in European Journal of Inorganic Chemistry
Description | The synthesis of a range of new spin-crossover complexes, some of them incorporating photo-isomerisable azobenzene substituents. The observation of light-induced switching of metal spin-states in solution at room temperature, triggered by UV irradiation. |
Exploitation Route | The design of new room temperature, photoswitchable compounds for devices or nanoscience. |
Sectors | Chemicals |
Description | Responsive Mode Grant |
Amount | £513,588 (GBP) |
Funding ID | EP/I014039/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 08/2011 |
End | 03/2015 |
Description | ICMCB, CNRS, Bordeaux, France; photomagnetic measurements |
Organisation | National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) |
Country | France |
Sector | Academic/University |
PI Contribution | Provision of samples |
Collaborator Contribution | Photomagnetic measurements |
Impact | Joint publications since 2006 (by doi): 10.1039/c7cc07990g; 10.1016/j.poly.2017.01.029; 10.1002/chem.201406307; 10.1021/acs.inorgchem.5b00614; 10.1002/ejic.201201100; 10.1039/c2dt12122k; 10.1039/b907094j; 10.1039/b708971f; 10.1002/chem.200601312; 10.1039/b618480d; 10.1039/b601366j |
Description | University of Barcelona, shape measures analysis |
Organisation | University of Barcelona |
Country | Spain |
Sector | Academic/University |
PI Contribution | Provision of crystallographic data |
Collaborator Contribution | Computational analysis of coordination geometries |
Impact | One joint publication in Coordination Chemistry Reviews: doi 10.1016/j.ccr.2014.08.006 |
Start Year | 2014 |
Description | University of Manchester, magnetic measurements |
Organisation | University of Manchester |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Provision of samples |
Collaborator Contribution | Variable temperature magnetic susceptibility measurements |
Impact | Published joint papers (by doi): 10.1039/c1sc00584g 10.1039/c3cc43613f 10.1039/c2cc30873h 10.1039/c2dt31736b 10.1002/ejic.201201100 10.1016/j.poly.2013.01.057 |
Start Year | 2011 |