[Triumf-seminars] TRIUMF Colloquium today at 14:00

[TRIUMF Seminars]

Date/Time: Thu 2011-09-22 at 14:00

Location:  Auditorium          

Speaker:   Daniel Leznoff (Simon Fraser University)

Title:     Cyanide-based Coordination Polymers in Molecular Magnetism and Beyond

Abstract: Metal-containing coordination polymers are a type of solid-state material that allows chemists to exquisitely design infinite arrays with particular properties based on the "lego building-block" approach.  The use of cyanometallate building blocks [M(CN)x]n- to generate coordination polymers has a distinguished history in molecule-based magnetism research, starting with the prototypical Prussian Blue-type materials, which were probably the first coordination polymers ever prepared (in 1710).  A brief outline of the "hottest" topics in molecular-magnetism chemistry research that is of potential interest to physicists will be described, to put our own research into context.  

Most cyanometallate polymers use octahedral building blocks to generate molecule-based magnetic materials.  In comparison, we have been exploring neglected linear d10-[Au(CN)2]- building blocks in coordination polymers to take advantage of attractive aurophilic ("gold-loving") interactions to increase structural dimensionality.  Simple ligand-free "mineral-like" polymers of the form M[Au(CN)2]2(H2O)x (M=Mn to Cu) have unprecedented aqua-bridged metal chain structures; their magnetic behaviour changes as a function of metal cation and data indicates that, overall, water is a surprisingly weak mediator of magnetic exchange compared with hydroxo or oxo-bridges.  The structures and magnetic properties change drastically upon dehydration to M[Au(CN)2]2 systems, or by substituting the linear [Au(CN)2]- building block for square-planar [Au(CN)2X2]- (X=CN, Br).  The critical importance of the muon-spin relaxation data (obtained at TRIUMF with Prof. J. Sonier) to detect magnetic order or spin-freezing phase transitions in all these systems will be detailed. 


Stimulants available 15 minutes before the talk.

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