The first amino acid manganese cluster: a [Mn(IV)2Mn(III)3] DL-valine cage

Constructing "Closed" and "Open" {Mn8} Clusters

Use of the 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane ligand, LH₃, in manganese chemistry affords access to two structurally related {Mn₈} clusters: a "closed" {Mn^III ₆Mn^II ₂} puckered square wheel of formula [Mn₈L₂(LH)O₃(OH)₂(MeO)₂Br(imH)(H₂O)₃](Br)₃ (1; imH = imidazole) and an "open" {Mn^III ₈} rod of formula [Mn^ΙΙΙ ₈L₂O₄(aibH)₂(aib)₂(MeO)₆(MeOH)₂](NO₃)₂ (2, aibH = 2-amino-isobutyric acid). In each case the triaza ligands, L/LH, direct the formation of {Mn₃} triangles with their N atoms preferentially bonding to the Jahn-Teller axes of the Mn^III ions. Subsequent self-assembly is dependent on the anion of the Mn salt and the identity of the organic coligand employed-the terminally bonded imidazole and the chelating/bridging amino acid. The {Mn₃} triangles fold up on themselves in 1, forming a wheel. However, the syn, syn-bridging carboxylates in 2 prevent this from happening, instead directing the formation of a linear rod. Magnetic susceptibility and magnetization measurements reveal competing ferro- and antiferromagnetic interactions in both complexes, the exchange being somewhat weaker in 1 due to the presence of Mn^II ions.

The first amino acid bound manganese–calcium clusters: a {[MnIII3Ca]2} methylalanine complex, and a [MnIII6Ca] trigonal prism

The use of methylalanine in manganese/calcium chemistry has led to the synthesis and characterization of the first manganese/calcium amino acid containing polynuclear clusters.

Polynuclear ampyrone based 3d coordination clusters

The use of a monoanionic Schiff base ligand in transition (Co, Ni and Cu) coordination chemistry yields mono-, tetra- and pentanuclear coordination clusters with different structural motifs.

A flow-system array for the discovery and scale up of inorganic clusters

The batch synthesis of inorganic clusters can be both time consuming and limited by a lack of reproducibility. Flow-system approaches, now common in organic synthesis, have not been utilized widely for the synthesis of clusters. Herein we combine an automated flow process with multiple batch crystallizations for the screening and scale up of syntheses of polyoxometalates and manganese-based single-molecule magnets. Scale up of the synthesis of these architectures was achieved by programming a multiple-pump reactor system to vary reaction conditions sequentially, and thus explore a larger parameter space in a shorter time than conventionally possible. Also, the potential for using the array as a discovery tool is demonstrated. Successful conditions for product isolation were identified easily from the array of reactions, and a direct route to 'scale up' was then immediately available simply by continuous application of these flow conditions. In all cases, large quantities of phase-pure material were obtained and the time taken for the discovery, repetition and scale up decreased.