Chemistry

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3 March 2021

Seminar - Switchable Paramagnets and their Integration into Nanomaterials

Presented By Dr Grace Morgan (University College Dublin)

About this event

Abstract

Thermal spin state switching in many transition metal complexes of iron, manganese and cobalt has been widely studied in the solid state, with a strong focus on the magnetic properties. Of equal importance is the photophysical characterisation in both the solid state and in solution. In some instances spin state switching can lead to long lived excited states in crystalline samples via Light Induced Excited Spin State Trapping (LIESST). The LIESST mechanism in Fe3+ (d6), whereby two electrons are excited and spin flipped by a single photon, has been extensively debated in recent years but much less studied is the long- lived LIESST mechanism in Fe3+ (d5). Some recent magnetic and photophysical properties of Mn3+ and Fe3+ spin crossover (SCO) complexes will be presented here with a rationalisation of the difference between them.

We have also examined how to develop the materials assembly of paramagnetic complexes and our work on stabilizing and isolating monodisperse nanoparticles, nanocrystals, thin films, Langmuir-Blodgett surface mono- and multilayers and hysteretic soft media assemblies will be discussed. The dimensional reduction of SCO complexes has been observed to have an effect on the magnetic behaviour of the materials which is a result of the electronic bistability being related to the collective behaviour of the SCO centres in the crystalline lattice. Here, we now probe magnetic, electrostatic and conductive properties of SCO Fe3+ and Mn3+ complexes at the nanoscale. Recent work on nanoparticles, nanowires, nanofibers and nanocrystals and their piezoelectric and conductive properties will be discussed.