Covalently-linked, Rigid Cofacial Metalloporphyrin Dimers and their Magnetic and Spectroscopic Properties

A. Diodati, S. Liu, Z. Becerra, H.-P. Cheng, A. Angerhofer, G. Christou

University of Florida, Northwestern University

Research in our group in recent years has included the synthesis and study of covalently-linked oligomers of metal-oxo clusters that exhibit novel the appropriate magnetic and quantum properties to make them potential spin-based molecular components in new 21^st-century technologies. Such properties include exchange-biased quantum tunneling of magnetization (EB-QTM) and quantum superposition and entanglement states (QSE), all arising from weak exchange interactions between the linked clusters. Following our previous work using trinuclear Mn^III₃ and dinuclear Mn^IIIMn^IV clusters with S = 6 and S = ½ ground states, respectively, we have more recently shifted our focus to linking single-ion complexes in order to obtain products that are more chemically robust and that also allow tunability of the metal ions incorporated. Therefore, we have now targeted and successfully synthesized a family of rigid, covalently linked, cofacial, bis-metalloporphyrin complexes designed to exhibit exchange interactions of the desired magnitude. This presentation shall describe the organic synthesis of the targeted bis-porphyrins, and the preparation and crystal structures of representative bis-metalloporphyrin derivatives, as well as their DFT computational results, SQUID magnetic properties, and electron paramagnetic resonance studies.