Secondary building units as the turning point in the development of the reticular chemistry of MOFs

Our journey of developing multifunctional metal-organic frameworks

Metal-organic frameworks (MOFs) are organic-inorganic hybrid solids constructed from the coordination interaction of metal ions/clusters with organic linkers, which currently represent one of the most rapidly expanding platforms for new functional materials. Based on well-established approaches, involving tuning the pore sizes, incorporation of functional sites and post-synthetic modification, the pore structures of MOFs can be readily controlled for multifunctional applications. In this brief review, we summarize and highlight our research progresses during our journey on developing functional MOFs for various applications including gas storage, gas separations, luminescent sensing, proton conduction, and molecular recognitions.

From Octahedral to Icosahedral Metal-Organic Polyhedra Assembled from Two Types of Polyoxovanadate Clusters

Design and synthesis of metal-organic polyhedra (MOPs) with targeted geometries from predetermined secondary building units (SBUs) is a long-standing challenge in chemistry and material science. Theoretical prediction shows that there are 6 possible polyhedra from the 3-coordinated, 4-coordinated octahedron ((3,4)-c octahedron) to (3,5)-c icosahedron with minimal transitivity (simplest possible). Except for one missing polyhedron (mtr) due to the unfavorable angles, we report five MOPs based on these structures, including an octahedral (3,4)-c VMOP-21 (rdo), an icosahedral (3,5)-c VMOP-25 (trc), and three intermediate derived trinodal (3,4,5)-c VMOP-22-24 (ghm, hmg, xum). Remarkably, all these MOPs obey the minimal transitivity principle and are consistent with geometrical predictions.

Isoreticular Tp*–W–Cu–S cluster-based one-dimensional coordination polymers with an uncommon [Tp*WS3Cu2] + [Cu] combination and their third-order nonlinear optical properties

Three isoreticular W/Cu/S 1D coordination polymers show good third-order NLO performance.

Bimetallic MOF-templated synthesis of alloy nanoparticle-embedded porous carbons for oxygen evolution and reduction reactions

Pyrolysis of metal–organic frameworks (MOFs) to produce metal nanoparticles embedded inside a porous carbon matrix (M@PC) has drawn a lot of attention in recent years.

Development of a new Lindqvist-like Fe6 cluster secondary building unit for MOFs

In this work, a novel Lindqvist-like Fe6 cluster was introduced as an SBU to construct a new family of Fe-cluster organic frameworks.

Electron delocalization in single-layer phthalocyanine-based covalent organic frameworks: a first principle study

In this work, we first investigate the localized electronic states in the band structures of three single-layer COFs based on typical building units of COFs chemistry. Our results confirm that the polar nature of strong bonds in these building units is a hindrance to a fully delocalized structure and disfavors the band-like mechanism of transport. We then show that a rational design of the building units can lead to dispersive band states in the electronic structure and results in conducting single-layer COFs. We demonstrate this strategy by investigating the charge carrier transport in a series of single-layer Ni-phthalocyanine (NiPc) covalent organic frameworks (COFs), namely, NiPc-P, NiPc-2P, and NiPc-3P. Three proposed COFs exhibit semiconducting band gaps ranging from 0.55 to 0.91 eV. Their room-temperature intrinsic mobility is predicted to be in range of 200–600 cm² V⁻¹ s⁻¹ and 20 000–60 000 cm² V⁻¹ s⁻¹ for electrons and holes, respectively, which are comparable to those of phosphorene and higher than those of the trigonal prismatic molybdenum disulfide. NiPc are dynamically and mechanically stable and can be synthesized via the co-evaporation between Ni and corresponding tetracyano linkers. Importantly, we demonstrate that the properties of the single-layer COFs can be tuned by engineering the organic building blocks. Our theoretical study not only provides insight into the design principles for semiconducting single-layer COFs but also highlights the significance of reticular chemistry in the development of a new generation of two-dimensional materials for optoelectronic applications.

A series of single-layer phthalocyanine-based covalent-organic frameworks (COFs) are shown to possess tunable delocalized electronic states which are attractive for optoelectronic applications.

Two CuxIy-based copper–organic frameworks with multiple secondary building units (SBUs): structure, gas adsorption and impressive ability of I2 sorption and release

Two Cu_xI_y-based copper–organic frameworks with multiple SBUs have been successfully synthesized. Both the compounds exhibit high performance for I₂ sorption and release.

New linker installation in metal–organic frameworks

Installation of new organic components (including multitopic anionic and neutral linkers) in MOFs and MOPs for multicomponent materials.

Adsorption of anthracene substitutes into suprachannels: bulk vs. included guests

Investigation of FRET of included anthracene substitutes within unusual hydrophobic suprachannels was carried out.