Isostructural mesoporous ionic crystals as a tunable platform for acid catalysis

Abstract

The catalytic activities are highly dependent on the components of meso-PICS.

Polyoxocationic antimony oxide cluster with acidic protons

“…Notably, the turnover frequency (TOF) reached a high value of 50 per hour with 0.1 mol % of HSbOI at 1 hour, which is higher than that of a typical solid acid catalyst, a scandium triflate–grated mesoporous silica (TON ~ 200 and TOF < 1 at 353 K) ( 44 ). It is known that the activity in the Barbier-Grignard reaction increases by increasing the acid strength of POM-based solids as catalysts [i.e., p K a (where K a is the acid dissociation constant) of the metal aqua ions as counter cations] ( 45 ), so these results confirm the highly acidic property of HSbOI . Because HSbOI is not porous (fig.…”

Frontiers and applications of polyoxometalates-based porous ionic crystals

“…的晶体结构 Figure 3 (Color online)Schematic diagram of the reversible absorption-release of redox-induced cations (K + ) [45] . PPICs 还具有强酸性。主要原因包括以下 3 点：(1)与 POMs 本身的性质有关。Uchida 等人 [48] 合成的等结构 PPICs:…”

“…)的晶体图 [48] ; [49] ; (c) 由 1 或 2 催化的 Barbier-Grignard 反应的产率-时间图 [48] ; (d) 在 373 K 下由 3(封闭符号)或 4(空心符号)催化的频哪醇重排的 产率-时间图 [49] [49] ; (c) Time courses of the Barbier-Grignard reaction catalyzed by 1 or 2 [48] ; (d) Time courses of pinacol rearrangement catalyzed by 3 (closed symbols) or 4…”

Structure-function Relationships of Porous Ionic Crystals (PICs) Based on Polyoxometalate Anions and Oxo-centered Trinuclear Metal Carboxylates as Counter Cations

“…34 It is well known that metal aqua ions [M(H 2 O) m ] n+ are subject to hydrolysis and form Brønsted acid sites (H + ). 56 Quite recently, we have reported that the catalytic activities of isostructural meso-PICs can be controlled by the types of counter cations (M n+ ), which are hydrated and exist as metal aqua ions in the mesopores: 57 The catalytic activities of these meso-PICs in the Barbier-Grignard reaction highly depended on the first hydrolysis constants of the metal ions, and thus Brønsted acidities of the metal aqua ions. Besides, the catalytic activities were higher for the meso-PICs comprising [ show that meso-PICs can serve as an ideal platform for rational designing of heterogeneous acid catalysts.…”