Heteropoly Blue/Protonation-Defective Graphitic Carbon Nitride Heterojunction for the Photo-Driven Nitrogen Reduction Reaction.

The establishment of a heterojunction is a crucial strategy to design highly effective nonnoble metal nanocatalysts for the photocatalytic nitrogen reduction reaction (PNRR). Heteropoly blues (r-POMs) can act as electron-transfer mediators in PNRR, but its agglomeration limits the further promotion of PNRR productivity. In this work, we construct a protonation-modified surface of N-vacancy g-C3N4 (HV-C3N4), achieving the high dispersion of r-POMs via the surface modification strategy. Enlightened by the synergy effect of the nitrogenase, r-POMs were anchored onto HV-C3N4 nanosheets through an electrostatic self-assembly method for preparing r-POMs-based protonation-defective graphitic carbonitride (HV-C3N4/r-POMs). As an electron donor, r-PW12 can match with the energy level of HV-C3N4 to build a heterojunction. The electron redistribution of the heterojunction facilitates the optimization of the electronic structure for enhancing the performance of PNRR. HV-C3N4/r-PW12 exhibits the best PNRR efficiency of 171.4 µmol L-1 h-1, which is boosted by 94.39% (HV-C3N4) and 86.98% (r-PW12). The isotope 15NH4+ experiment proves that ammonia is derived from N2, not carbon nitride. This study opens up a crucial view to achieve the high dispersion of r-POMs nanoparticles and develop high-efficiency nonnoble metal photocatalysts for the PNRR.

2D Co-crystallization of molecular homologues promoted by size complementarity of the alkyl chains at the liquid/solid interface.

Co-crystallization of organic molecules is an important strategy for the fabrication of molecular materials. In this contribution, we investigated the mixing behavior of 5-(benzyloxy)-isophthalic acid homologues (BIC-Cn, n = 6, 8, 10, 12, and 14) at the liquid/solid interface using a scanning tunneling microscope. Deposition of the single component of BIC-Cn always results in typical honeycomb networks, whereas co-deposition of two BIC-Cn homologues leads to hybrid double-walled honeycomb networks or phase separation depending on the difference in the length of their alkyl chains. 2D co-crystallization can only be realized for BIC-C6/BIC-C10 or BIC-C8/BIC-C12 which have a four-methyl unit difference in their alkyl chains. The size complementarity of the alkyl chains in the two components suggests that it is responsible for the 2D co-crystallization, though hydrogen bonding contributes a lot both to the pristine honeycomb network and to the hybrid co-crystal. This result is of importance for understanding the role of van der Waals interaction and its interplay with hydrogen bonding in 2D co-crystallization.

Borromean-entanglement-driven assembly of porous molecular architectures with anion-modified pore space.

A series of metal-organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1⋅Mn⊃OH(-), 2⋅Mn⊃SO(4)(2-), 3⋅Mn⊃bdc(2-), 4⋅Eu⊃SO(4)(2-) (H(2)BpybcCl(2) = 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridinium dichloride, H(2)bdc = 1,4-benzenedicarboxylic acid) have been obtained by a self-assembly process. Single-crystal X-ray-diffraction analysis revealed that all of these compounds contained the same n-fold 2D→3D Borromean-entangled topology with irregular butterfly-like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non-interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1⋅Mn⊃OH(-) further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π-conjugated structures.

New prototype isoreticular metal-organic framework Zn(4)O(FMA)(3) for gas storage.

A new isoreticular metal-organic framework Zn(4)O(FMA)(3).xG (1; FMA = fumarate; G = guest molecules) of a primitive cubic net was synthesized and structurally characterized. With intersecting pores of about 6.8 x 6.8 A, the activated 1a exhibits high gas adsorption with respect to H(2), CH(4), and CO(2).

Robust metal-organic framework enforced by triple-framework interpenetration exhibiting high H2 storage density.

A microporous metal-organic framework 1 Zn 2(CNC) 2(DPT).G [CNC = 4-Carboxycinnamic; DPT = 3,6-Di-4-pyridyl-1,2,4,5-tetrazine; G = guest molecules] was synthesized and structurally characterized by a triply interpenetrated primitive cubic net with 1D pores of about 3.7 A. 1 is highly robust enforced by triple framework interpenetration through weak van der Waals interactions, thus the activated 1b takes up 1.28 wt % hydrogen gas and exhibits high hydrogen storage density of 95.2% at 1 atm and 77 K.

A Homochiral Multifunctional Metal-Organic Framework with Rod-Shaped Secondary Building Units.

A new homochiral multifunctional metal-organic framework, [Zn2(CTBA)2·H2O] (JUC-112), was synthesized under solvothermal conditions, through the design of chiral ligand 4-(3-carboxy-2,2,3-trimethylcyclopentanecarboxamido) benzoic acid (H2CTBA) based on camphoric acid as building block. The crystal structure of the new material is a 2-dimensional (2D) chiral layer packed with infinite rod-shaped secondary building units (SBUs). The homochiral framework was identified by circular dichroism (CD) spectrum. Thermogravimetric measurement indicates its high thermal stability up to 450 °C. In addition, JUC-112 exhibits the capability of separating water from alcohols, second-order nonlinear optical effect, and photoluminescence.

Multimodal Zr-Silicalite-1 zeolite nanocrystal aggregates with interconnected hierarchically micro-meso-macroporous architecture and enhanced mass transport property.

Hierarchical porous architecture with interconnected trimodal micro-meso-macroporous systems constructed from uniform zeolite Zr-doped silicalite-1 nanocrystals has been prepared. The synthesis has been made by using glycerin as a reaction medium via a quasi-solid-state crystallization of hierarchically meso-macroporous zirconosilicate precursor under the effect of the structure directing agent TPAOH. The presence of glycerin is crucial in the synthesis systems to maintain the porous hierarchy. The pores inter-connectivity, Zr location in the framework, the acidity and the catalytic activity have been studied by laser-hyperpolarized (129)Xe NMR spectroscopy, UV-visible spectroscopy, temperature-programmed desorption of ammonia and the catalytic isopropylbenzene cracking probe reaction, respectively. The products possess well-defined macrochannels interconnected with mesopores located in the macropore walls, which in turn have been constructed from microporous MFI-type zeolite units. (129)Xe NMR study indicated that the hierarchically micro-, meso-, macro-pore systems are homogeneously distributed throughout the final materials and well interconnected, which is important for molecular diffusion. The TPD-NH(3) investigation revealed that the hierarchically micro-meso-macroporous materials constructed from zeolite Zr-Silicalite-1 nanocrystals present strong acidity.

A novel microporous MOF with the capability of selective adsorption of xylenes.

A novel 3D metal-organic framework (MOF) with 2D rhombic channels was synthesized for selective adsorption of p-xylene from xylene isomers by acting as a molecular sieve.

A new two-dimensional CdII coordination polymer constructed by pyrazine-2,3-dicarboxylate.

In the title compound, poly[mu(5)-pyrazine-2,3-dicarboxylato-cadmium(II)], [Cd(C(6)H(2)N(2)O(4))](n) or [Cd(pdc)](n), where pdc is the pyrazine-2,3-dicarboxylate anion, the Cd(II) atom is six-coordinated by five carboxylate O atoms and one N atom from five different pdc ligands in a distorted octahedral CdO(5)N coordination geometry. Two Cd(II) atoms are bridged by carboxylate groups of the pdc ligands to create a dimeric unit. The dimeric units are further connected by the pdc ligands to generate an interesting two-dimensional structure.

Porous coordination polymers with zeolite topologies constructed from 4-connected building units.

Two novel 3D coordination polymers, Cd(CTC)(H2O).(H2PIP)(0.5)(H2O) (1) with zeolite ABW topology and Cd(CTC).(HIPA) (2) with zeolite BCT topology, have been synthesized by constructing inorganic and organic 4-connected building units and using the organic bases as templates, and the frameworks of and not only expand the original structures of zeolites ABW and BCT, but also exhibit significant advantages over them in terms of thermal stability, ion exchange and adsorption.

Microporous metal-organic framework constructed from heptanuclear zinc carboxylate secondary building units.

A novel, three-dimensional, noninterpenetrating microporous metal-organic framework (MOF), [Zn7O2(pda)5(H2O)2]5 DMF4 EtOH 6 H2O (1) (H2PDA=p-phenylenediacrylic acid, DMF=N,N-dimethylformamide, EtOH=ethanol), was synthesized by constructing heptanuclear zinc carboxylate secondary building units (SBUs) and by using rigid and linear aromatic carboxylate ligands, PDA. The X-ray crystallographic data reveals that the seven zinc centers of 1 are held together with ten carboxylate groups of the PDA ligands and four water molecules to form a heptametallic SBU, Zn7O4(CO2)10, with dimensions of 9.8 x 9.8 x 13.8 A3. Furthermore, the heptametallic SBUs are interconnected by PDA acting as linkers, thereby generating an extended network with a three-dimensional, noninterpenetrating, intersecting large-channel system with spacing of about 17.3 A. As a microporous framework, polymer 1 shows adsorption behavior that is favorable towards H2O and CH3OH, and substantial H2 uptake. In terms of the heptanuclear zinc carboxylate SBUs, polymer 1 exhibits interesting photoelectronic properties, which would facilitate the exploration of new types of semiconducting materials, especially among MOFs containing multinuclear metal carboxylate SBUs.