Network Topology of a Hybrid Organic Zinc Phosphate with Bimodal Porosity and Hydrogen Adsorption

Abstract

In the last decade, the synthesis of nanoporous materials with extended network topologies has advanced extensively owing to the increasing demand for functional materials in applications involving molecular recognition, shape-selective catalysis, fluid separation, and hydrogen gas storage.[1] Until now, two major categories of nanoporous structures have been under intense investigation: one with whole inorganic framework, such as silica-based zeolites, germanates, and phosphorous-based metal oxides; and another with organic-inorganic hybrid frameworks; that is, porous coordination polymers [2] and metal-organic frameworks (MOFs).[3] The largest pore and/or channel opening that has been observed in inorganic frameworks are 18-membered rings (18MR) in silicates, [4] 24MR in metal phosphates, [5] 26MR in metal phosphites, [6] and 30MR in germanates. [7] In the hybrid frameworks, however, the cavities were determined from pore structure analysis based upon gas sorption studies. By using bulky organic units to co-construct the framework, even higher porosity or larger pores can be produced. For example, the pore size found in the framework MIL-101 [8] was up to 4.6 nm, and the void space in MOF-177 [9] was reported to increase the size of a unit-cell volume by up to 81 %, thus substantially surpassing the volume of inorganic structures.Exploration of enhanced porosity and even new properties in the inorganic framework have thus been pursued by mediating with organic building units. To date, transforming inorganic frameworks into hybrid frameworks has only been possible in phosphate/phosphite (MPO) systems; few organic molecules are found to be suitable, for example, the smallest oxalate linker and certain polyamine molecules. Encouragingly however, quite a few unique three-dimensional metal oxalatophosphates [10] and pillar-layered organo-metallophosphates (OMPO) [11] have been formed that have extra-large channels with interesting properties. The oxalate-mediated nanoporous gallium phosphates of NTHU-6[10a] or NTHU-7, [10b] with their unprecedented photoluminescence properties, has established a new class of LED color-conversion phosphors. Aryl carboxylates, such as benzene dicarboxylate (bdc) or benzene-1,2,4,5-tetracarboxylate (btec), which are effective organic building units of MOFs or coordination polymers, had not been found to adapt to MPOs until the discovery of (H 2 tmdp)[(ZnHPO 4 ) 2 (bdc)] (tmdp = 4,4'-trimethylenedipyridine; NTHU-2),[11a] the first bdc-mediated OMPO compound, in 2004. This compound has gismondinelike inorganic sheets pillared by bdc to give nanometer-sized channels and a remarkable gas sorption behavior; of vital importance, this sorption revealed bimodal pore-size distributions. To gain a deeper insight into the intriguing and useful porous properties, we have focused on the study of carboxylate-incorporated MPO frameworks. Herein we report the first btec-mediated metal phosphate compound, (Hbpy)-[Zn 2 PO 4 (btec)(Hbpy) 2 ] (bpy = 4,4'-bipyridine), designated NTHU-8. This compound e...

Porous Metal Carboxylate Boron Imidazolate Frameworks

“…Finally, these tubes are cross‐linked along the b and c directions to generate a 3D framework (Figure 1 g). This structural feature of MC‐BIF‐4S is similar to that of a recently reported zincophosphate constructed from 1D zinc phosphate four‐ring columns interlinked by organic ligands 11…”

Layered Zinc Phosphates with Photoluminescence and Photochromism: Chemistry in Deep Eutectic Solvents

“…Compound 9‐MV is the first metal phosphate lattice incorporating the [(CH 3 ) 2 bpy] 2+ ion, also known as methylviologen dication (MV 2+ ). In most bpy‐containing MPOs, the bpy molecules prefer coordination as pillaring ligands17 to protonation as a template,18 let alone undergoing N , N ′‐dimethylation. When exposed to X‐rays ( λ =1.5418 Å in powder diffraction measurements), the orange color of 9‐MV immediately turned to slate gray (Figure 2), that is, MV 2+ dications were reduced to MV .+ radicals.…”

Multi-stimulus responsive properties of a Cd-MOF based on tetraphenylethylene

“…Metal-organic frameworks (MOFs) are a fascinating class of inorganic-organic hybrid crystalline materials with high porosity, excellent surface areas and a tunable pore structure. [19][20][21][22][23][24][25] And they are regarded as a platform for sensing, 26 gas adsorption/separation, 27,28 catalysis, 29 and so on. It is worth noting that benefiting from the framework structure, some functionalized MOFs display certain properties that the corresponding ligands do not possess.…”