Formation of a Highly Reactive Cobalt Nanocluster Crystal within a Highly Negatively Charged Porous Coordination Cage

Abstract

Earth-abundant first-row transition-metal nanoclusters (NCs) have been extensively investigated as catalysts. However, their catalytic activity is relatively low compared with noble metal NCs. Enhanced catalytic activity of cobalt NCs can be achieved by encapsulating Co NCs in soluble porous coordination cages (PCCs). Two cages, PCC-2a and 2b, possess almost identical cavity in shape and size, while PCC-2a has five times more net charges than PCC-2b. Co cations were accumulated in PCC-2a and reduced to ultra-small Co NCs in situ, while for PCC-2b, only bulky Co particles were formed. As a result, Co NCs@PCC-2a accomplished the highest catalytic activity in the hydrolysis of ammonium borane among all the first-row transition-metals NCs. Based on these results, it is envisioned that confining in the charged porous coordination cage could be a novel route for the synthesis of ultra-small NCs with extraordinary properties.

Accelerating Crystallization of Open Organic Materials by Poly(ionic liquid)s

“…TheR h/CC3R-Ptriaz (particle size:1 .1 AE 0.2 nm) shows at urnover frequency( TOF) of 278 min À1 (Figure 5c,e), which is comparable to the highest activity among the cage immobilized catalysts for AB methanolysis reaction (304.4 min À1 for Ru NPs@PCC-2 catalyst). [27] Such activity is 1.9 times higher than that of the CC3R without Ptriaz (TOF:1 50 min À1 ,p article size:1 .9 AE 0.5 nm) (Figure 5d,e), or 21 times higher than support-free Rh catalyst with aggregated particles (TOF:1 3min À1 )( Supporting Information, Figures S22, S23). Since the cage and PIL are inert to the reaction (Supporting Information, Figures S24, S25), such enhanced activity could be reasonably assigned to the enhanced dispersibility in solution as well as the smaller size of Rh clusters,w hich would facilitate the mass transfer between the Rh and reactants.…”

Ultrastable and Highly Catalytically Active N‐Heterocyclic‐Carbene‐Stabilized Gold Nanoparticles in Confined Spaces

“…[6,7] Over the past decade,c ontrol over the size,s hape, distribution and catalytic tuning of MNPs has advanced through the use of porous templates,s uch as metal-organic frameworks (MOFs), [8][9][10][11][12][13][14] covalent organic frameworks (COFs), [15][16][17][18] and porous coordination cages. [19][20][21][22] Of this wide variety of materials,d iscrete three-dimensional (3D) organic molecular cages with guest accessible cavities have recently emerged as an ew type of functional-materials platform to prepare MNPs with precisely controlled sizes and shapes. [23][24][25][26][27][28] Besides the well-defined cage structure, which provides ac onfined cage environment and can effectively prevent particle aggregation, enhancing particle stability and solubility,the anchoring functional groups inside the cavity have been established to be critical.…”

Accelerating Crystallization of Open Organic Materials by Poly(ionic liquid)s

“…TheR h/CC3R-Ptriaz (particle size:1 .1 AE 0.2 nm) shows aturnover frequency (TOF) of 278 min À1 (Figure 5c,e), which is comparable to the highest activity among the cage immobilized catalysts for AB methanolysis reaction (304.4 min À1 for Ru NPs@PCC-2 catalyst). [27] Such activity is 1.9 times higher than that of the CC3R without Ptriaz (TOF:150 min À1 , particle size:1 .9 AE 0.5 nm) (Figure 5d,e), or 21 times higher than support-free Rh catalyst with aggregated particles (TOF: 13 min À1 )( Supporting Information, Figures S22, S23). Since the cage and PIL are inert to the reaction (Supporting Information, Figures S24, S25), such enhanced activity could be reasonably assigned to the enhanced dispersibility in solution as well as the smaller size of Rh clusters,w hich would facilitate the mass transfer between the Rh and reactants.…”