Microperoxidase-11 has for the first time been successfully immobilized into a mesoporous metal-organic framework (MOF) consisting of nanoscopic cages and it demonstrates superior enzymatic catalysis performances compared to its mesoporous silica counterpart.

Gas separation using molecular sieves (MSs) is a environmentally benign, energy-conserving alternative to traditional separation processes, such as distillation and absorption. [1] When using zeolite MSs, [2][3][4] an accurate one-on-one match between the mesh size and the separation need is essential. However, when the size disparity of the two gases to be separated is small, a MS with the optimum mesh size is not always readily available. A mismatch inevitably leads to an inefficient separation. Recently, titanosilicate was shown to possess superior flexibility over that of traditional zeolites; a few MSs with discrete mesh sizes were made based on the degree of dehydration of this material at various temperatures.[5] Nevertheless, a MS with more than one mesh size has never been made in the past. Herein, we report the design, synthesis, and application of a novel mesh-adjustable molecular sieve (MAMS-1) that possesses an infinite number of mesh sizes. MAMS-1 is based on a metal-organic framework (MOF), compounds known for their dynamic porous properties.[6] However, the concept of a MAMS has never appeared in the literature prior to the present work. MAMS-1 represents a MOF-based MS whose mesh can be adjusted continuously. The mesh range of MAMS-1 falls between 2.9 and 5.0 , which covers the size range of almost all commercially important gas separations. When the temperature is precisely controlled, any mesh size within this range can be accurately attained. Gas separations such as those of N 2 /O 2 and N 2 /CH 4 , which are normally difficult to achieve, are readily attainable by using MAMS-1. In principle, by precise temperature control, any two gases with a size difference can be separated by a MAMS.MOFs have attracted a great deal of attention because of their unique structures [6a, 7] and potential applications in catalysis, [8] separation, [9] and gas storage. [10] In particular, flexible MOFs [6] have caught enormous attention lately. Numerous studies have indicated that the key to constructing a flexible MOF lies in the utilization of weak interactions, such as hydrogen bonding, p-p stacking, and hydrophobic interaction, in addition to strong covalent and coordinative bonding.[6] Flexible MOFs based on hydrogen bonding have been widely studied, [6b,c] but those originating from p-p stacking and hydrophobic interaction [11] have rarely been explored.To make a MAMS, two factors must be taken into account: the material must have permanent porosity to hold gas molecules, and the pores must be flexible. The former usually requires strong bonds, while the latter implies weak interactions in the framework. These two seemingly irreconcilable prerequisites for a MAMS can be met simultaneously by using a graphitic structure, in which atoms in each layer are connected covalently but the layers are held together by weak interactions. One approach to such a graphitic MOF is to apply an amphiphilic ligand that consists of hydrophobic and hydrophilic ends, similar to a surfactant, [12] but with the hydrophilic ...

Open and close: Inspired by close‐packing of spheres, to strengthen the framework–H2 interaction in MOFs (metal‐organic frameworks), a strategy is devised to increase the number of nearest neighboring open metal sites of each H2‐hosting cage, and to align the open metal sites toward the H2 molecules. Two MOF polymorphs were made, one exhibiting a record high hydrogen uptake of 3.0 wt % at 1 bar and 77 K.

A mesoporous metal-organic framework possessing permanent porosity has been synthesized and characterized for the first time.

Narrow pores for high selectivity: The ytterbium metal–organic framework PCN‐17, which contains coordinatively (through SO42− ions) linked, doubly interpenetrated (8,3)‐nets (see picture), is stable up to 480 °C and exhibits selective adsorption of H2 and O2 over N2 and CO.

Solvothermal reactions of Cu(NO 3 ) 2 with azoxybenzene-3,3′,5,5′-tetracarboxylic acid (H 4 aobtc) or transstilbene-3,3′,5,5′-tetracarboxylic acid (H 4 sbtc) give rise to two isostructural microporous metal-organic frameworks, Cu 2 (abtc)(H 2 O) 2 • 3DMA (PCN-10, abtc ) azobenzene-3,3′,5,5′-tetracarboxylate) and Cu 2 (sbtc)-(H 2 O) 2 • 3DMA (PCN-11, sbtc ) trans-stilbene-3,3′,5,5′-tetracarboxylate), respectively. Both PCN-10 and PCN-11 possess significant enduring porosity with Langmuir surface areas of 1779 and 2442 m 2 /g (corresponding to BET surface areas of 1407 or 1931 m 2 /g, respectively) and contain nanoscopic cages and coordinatively unsaturated metal centers. At 77 K, 760 Torr, the excess gravimetric (volumetric) hydrogen uptake of PCN-10 is 2.34 wt % (18.0 g/L) and that of PCN-11 can reach 2.55 wt % (19.1 g/L). Gas-adsorption studies also suggest that MOFs containing CdC double bonds are more favorable than those with NdN double bond in retaining enduring porosity after thermal activation, although NdN has slightly higher H 2 affinity. The excess gravimetric (volumetric) adsorption at 77 K saturates around 20 atm and reaches values of 4.33% (33.2 g/L) and 5.05% (37.8 g/L) for PCN-10 and PCN-11, respectively. In addition to its appreciable hydrogen uptake, PCN-11 has an excess methane uptake of 171 cm 3 (STP)/ cm 3 at 298 K and 35 bar, approaching the DOE target of 180 v(STP)/v for methane storage at ambient temperature. Thus, PCN-11 represents one of the few materials that is applicable to both hydrogen and methane storage applications.

Metal-organic frameworks (MOFs) are a novel family of physisorptive materials that have exhibited great promise for methane storage. So far, a detailed understanding of their methane adsorption mechanism is still scarce. Herein, we report a comprehensive mechanistic study of methane storage in three milestone MOF compounds (HKUST-1, PCN-11, and PCN-14) the CH(4) storage capacities of which are among the highest reported so far among all porous materials. The three MOFs consist of the same dicopper paddlewheel secondary building units, but contain different organic linkers, leading to cagelike pores with various sizes and geometries. From neutron powder diffraction experiments and accurate data analysis, assisted by grand canonical Monte Carlo (GCMC) simulations and DFT calculations, we unambiguously revealed the exact locations of the stored methane molecules in these MOF materials. We found that methane uptake takes place primarily at two types of strong adsorption site: 1) the open Cu coordination sites, which exhibit enhanced Coulomb attraction toward methane, and 2) the van der Waals potential pocket sites, in which the total dispersive interactions are enhanced due to the molecule being in contact with multiple "surfaces". Interestingly, the enhanced van der Waals sites are present exclusively in small cages and at the windows to these cages, whereas large cages with relatively flat pore surfaces bind very little methane. Our results suggest that further, rational development of new MOF compounds for methane storage applications should focus on enriching open metal sites, increasing the volume percentage of accessible small cages and channels, and minimizing the fraction of large pores.

A highly porous porphyrin-based organic polymer, PCPF-1, was constructed via homo-coupling reaction of the custom-designed porphyrin ligand, 5,10,15,20-tetrakis(4-bromophenyl)porphyrin. PCPF-1 possesses a large BET surface area of over 1300 m(2) g(-1) (Langmuir surface area of over 2400 m(2) g(-1)) and exhibits strong hydrophobicity with a water contact angle of 135°, and these features afford it the highest adsorptive capacities for saturated hydrocarbons and gasoline among sorbent materials reported thus far, as well as render it the capability to remove oil from water.