Snapshots of Ce70 Toroid Assembly from Solids and Solution

Abstract

Crystallization at the solid-liquid interface is difficult to spectroscopically observe and therefore challenging to understand and ultimately control at the molecular level. The Ce70-torroid formulated [CeIV70(OH)36(O)64(SO4)60(H2O)10] 4- , part of a larger emerging family of MIV70- materials (M=Zr, U, Ce), presents such an opportunity. We have elucidated assembly mechanisms by X-ray scattering (small-angle scattering and total scattering) of solutions and solids, as well as crystallizing and identifying fragments of Ce70 by single-crystal X-ray diffraction. Fragments show evidence for templated growth (Ce5, [Ce5(O)3(SO4)12] 10- ) and modular assembly from hexamer (Ce6) building units (Ce13, [Ce13(OH)6(O)12(SO4)14(Η2Ο)14] 6- and Ce62, [Ce62(OH)30(O)58(SO4)58] 14- ). Ce62, an almost complete ring, precipitates instantaneously in the presence of ammonium cations as two torqued arcs that interlock by hydrogen boding through NH4 +, which can also be replaced by other cations, demonstrated with CeIII. Room temperature rapid assembly of both Ce70 and Ce62, respectively, by addition of Li+ and NH4 +, along with ion?exchange and redox behavior, invite exploitation of this emerging material family in environmental and energy applications.

Mechanistic Investigation of Enhanced Catalytic Selectivity toward Alcohol Oxidation with Ce Oxysulfate Clusters

“…Studies have shown that the high crystallinity allows the cerium fragments of the Ce 70 toroid to be crystallized and identified by single-crystal X-ray diffraction, which is highly significant for cluster formation understanding. 26 A series of heterometallic Ce IV /M (M = Mo VI , Re VII , and V V )-oxo clusters, of which the Ce IV /V V cluster catalyzed the oxidation of thioanisole, was synthesized and studied. 27 The electron deficiency on the Ce IV centers greatly increases the electrophilicity of the V V centers, thus enhancing the cluster's catalytic performance.…”

Metal–Oxo Cluster Formation Using Ammonium and Sulfate to Differentiate MIV (Th, U, Ce) Chemistries

“…22−24 For Ce 70 , the use of counterions has afforded the isolation of fragments that provide insight into selfassembly mechanisms. 25 The different ionic behavior and hydration enthalpies for the alkali metals have been shown to influence the formation of thorium nitrato complexes and U 6sulfate lattices. 26 Hard, or highly acidic, U IV , Ce IV , and Pu IV yielded larger molecular clusters, including U 12 , U 14 , 27 and U 16 ; 28,29 7 in addition to the ubiquitous hexamers; all of these resemble the parent fluorite-type oxide.…”

{Gd44Ni22}: a gigantic 3d–4f wheel-like nanoscale cluster with a large magnetocaloric effect

“…High-nuclearity 3d-4f metal oxide/hydroxide clusters (M > 25) have attracted extensive research attention because of their fascinating structures and interesting properties. [1][2][3][4][5][6][7][8][9][10] Among the different properties, a particularly interesting one is the molecular magnetocaloric effect (MCE). [11][12][13][14][15] The MCE is a phenomenon that leads to a reversible temperature change when a material is exposed to a changing magnetic field.…”