From one to three: a serine derivate manipulated homochiral metal-organic framework

Recent progress in the design, synthesis and applications of chiral metal-organic frameworks

Chiral Metal-Organic Frameworks (CMOFs) are unique crystalline and porous class of materials which is composed of organic linkers and metal ions. CMOFs surpass traditional organic and inorganic porous materials because of their tunable shape, size, functional diversity, and selectivity. Specific applications of CMOFs may be exploited by introducing desired functional groups. CMOFs have chiral recognition abilities, making them unique for chiral compound synthesis and separation. The CMOFs can be synthesized through different approaches. Two main approaches have been discussed, i.e., direct and indirect synthesis. Synthetic strategies play an essential role in getting desired properties in MOFs. CMOFs find potential applications in adsorption, asymmetric catalysis, luminescence, degradation, and enantioselective separation. The MOFs' porosity, stability, and reusability make them an attractive material for these applications. The plethora of applications of CMOFs have motivated chemists to synthesize novel MOFs and number of MOFs have been ever-escalating. Herein, the synthetic methods of CMOFs and their various applications have been discussed.

Chiral Metal-Organic Frameworks

In the past two decades, metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) assembled from metal ions or clusters and organic linkers via metal-ligand coordination bonds have captivated significant scientific interest on account of their high crystallinity, exceptional porosity, and tunable pore size, high modularity, and diverse functionality. The opportunity to achieve functional porous materials by design with promising properties, unattainable for solid-state materials in general, distinguishes MOFs from other classes of materials, in particular, traditional porous materials such as activated carbon, silica, and zeolites, thereby leading to complementary properties. Scientists have conducted intense research in the production of chiral MOF (CMOF) materials for specific applications including but not limited to chiral recognition, separation, and catalysis since the discovery of the first functional CMOF (i.e., d- or l-POST-1). At present, CMOFs have become interdisciplinary between chirality chemistry, coordination chemistry, and material chemistry, which involve in many subjects including chemistry, physics, optics, medicine, pharmacology, biology, crystal engineering, environmental science, etc. In this review, we will systematically summarize the recent progress of CMOFs regarding design strategies, synthetic approaches, and cutting-edge applications. In particular, we will highlight the successful implementation of CMOFs in asymmetric catalysis, enantioselective separation, enantioselective recognition, and sensing. We envision that this review will provide readers a good understanding of CMOF chemistry and, more importantly, facilitate research endeavors for the rational design of multifunctional CMOFs and their industrial implementation.

Advances in Chiral Metal-Organic and Covalent Organic Frameworks for Asymmetric Catalysis

Asymmetric catalysis is of crucial importance owing to the huge and rising demand for optically pure substances. Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), as two emerging crystalline porous materials, have presented great promising applications for heterogeneous asymmetric catalysis. The unique properties, such as, highly regular porous structures, prominent structural tunability, and well-ordered catalytic sites, render chiral MOFs (CMOFs) and chiral COFs (CCOFs) highly active and enantioselective for a large number of asymmetric catalytic organic transformations. Furthermore, they provide a useful platform for facile mechanistic understanding and catalyst design. This review provides an overview of the advancements in CMOFs and CCOFs for asymmetric catalysis. The designs, syntheses and structures of these crystalline porous materials, and their asymmetric catalytic performance are described. And the perspectives on challenges and opportunities in development of CMOFs and CCOFs are discussed. It is anticipated that this review will shed light on the heterogeneous asymmetric catalysis with CMOFs and CCOFs and motivate further research in this promising field.

Chiral porous organic frameworks and their application in enantioseparation

Porous organic frameworks (POFs) are a kind of porous material with a network structure composed of repeated monomers, which have excellent physical and chemical properties, such as a high surface area, high porosity, uniform pore sizes and structural diversity, and which have aroused broad interest among researchers. With the rapid development of materials science, increasingly more porous materials have been developed and applied, especially metal organic frameworks (MOFs) and covalent organic frameworks (COFs), which have been widely applied in the fields of luminous materials, catalytic research, adsorption and drug transport. One of the most important applications for chiral porous materials is in chiral separation and these materials have become a research hotspot in the field of chromatographic separation and analysis in recent years. In this review, from the viewpoint of enantioseparation, the synthesis of chiral porous materials and their applications in high-performance liquid chromatography (HPLC), capillary electrochromatography (CEC), and gas chromatography (GC) are reviewed. The typical applications of MOFs in solid-phase microextraction (SPME) are also discussed.

Homochiral metal–organic frameworks as heterogeneous catalysts

Homochiral metal–organic frameworks (HMOFs) are attractive materials for asymmetric catalysis because they possess high surface area and uniform active sites.

A Cu(ii) metal–organic framework with significant H2 and CO2 storage capacity and heterogeneous catalysis for the aerobic oxidative amination of C(sp3)–H bonds and Biginelli reactions

1 exhibits significant H₂, CO₂ storage capacity and heterogeneous catalytic activity for oxidative amination of C(sp³)–H bonds and Biginelli reactions.

Heterogeneous Catalysis in Zeolites, Mesoporous Silica, and Metal-Organic Frameworks

Crystalline porous materials are important in the development of catalytic systems with high scientific and industrial impact. Zeolites, ordered mesoporous silica, and metal-organic frameworks (MOFs) are three types of porous materials that can be used as heterogeneous catalysts. This review focuses on a comparison of the catalytic activities of zeolites, mesoporous silica, and MOFs. In the first part of the review, the distinctive properties of these porous materials relevant to catalysis are discussed, and the corresponding catalytic reactions are highlighted. In the second part, the catalytic behaviors of zeolites, mesoporous silica, and MOFs in four types of general organic reactions (acid, base, oxidation, and hydrogenation) are compared. The advantages and disadvantages of each porous material for catalytic reactions are summarized. Conclusions and prospects for future development of these porous materials in this field are provided in the last section. This review aims to highlight recent research advancements in zeolites, ordered mesoporous silica, and MOFs for heterogeneous catalysis, and inspire further studies in this rapidly developing field.

Synthesis of homochiral zeolitic metal–organic frameworks with amino acid and tetrazolates for chiral recognition

By mixing amino acids and tetrazolate ligands, a series of homochiral zeolitic metal–organic frameworks (ZMOFs) with ABW topology have been synthesized, which show permanent microporosity and potential enantioselective recognition ability.

Achiral aromatic solvent-induced assembly of 3-D homochiral porous 3d–4f heterometallic-organic frameworks based on isonicotinic acid

Via induction of achiral aromatic solvents, two 3-D monochiral 3d–4f MOFs (1 and 2) from the ligand HIN without any chiral auxiliary are uncommonly constructed. And the results show homochirality of 1 and 2 are enantiopurity rather than enantiomeric excess.

Emerging Multifunctional Metal-Organic Framework Materials

Metal-organic frameworks (MOFs), also known as coordination polymers, represent an interesting type of solid crystalline materials that can be straightforwardly self-assembled through the coordination of metal ions/clusters with organic linkers. Owing to the modular nature and mild conditions of MOF synthesis, the porosities of MOF materials can be systematically tuned by judicious selection of molecular building blocks, and a variety of functional sites/groups can be introduced into metal ions/clusters, organic linkers, or pore spaces through pre-designing or post-synthetic approaches. These unique advantages enable MOFs to be used as a highly versatile and tunable platform for exploring multifunctional MOF materials. Here, the bright potential of MOF materials as emerging multifunctional materials is highlighted in some of the most important applications for gas storage and separation, optical, electric and magnetic materials, chemical sensing, catalysis, and biomedicine.

Supramolecular Assemblies, Luminescence and Anion Exchange of Helical Pb(II) Complexes Based on Enantiomeric N-(2-pyridylmethyl) Alanine Ligands

Two pairs of PbII coordination polymers have been synthesised using pyridine-functionalised amino acid derivatives N-(2-pyridylmethyl)-L(D)-alanine hydrochlorides [(L-Hpala)Cl or (D-Hpala)Cl] and PbII salts. Their X-ray structures confirm their formulations as [Pb(L-pala) (NO3)]n, [Pb(D-pala)(NO3)]n, [Pb(L-pala)(Cl)]n and [Pb(D-pala)(Cl)]n. They show similar coordination environments of PbII cations with two kinds of five-membered chelating rings, which are further assembled into 1D helical chains through the bridging carboxylates from amino acids. Thermal and fluorescent properties of these complexes have also been investigated.

Structure-induced catalysis enhancement of Cu-amino catalysts for rapidly selective oxidation of sulfides in the presence of H2O2

A Cu-amino coordination polymer promotes rapid sulfoxidation of benzyl phenyl sulfide toward the sulfoxide with high conversion and selectivity.

Temperature-induced one-dimensional chiral Ag(i) linear chains and left-handed 21 helices: DFT studies, luminescence and SHG response

Two pairs of chiral coordination polymers have been synthesized with the same materials at 25 and 90 °C, respectively.

Applications of metal–organic frameworks in heterogeneous supramolecular catalysis

The contributions of MOFs to the field of heterogeneous supramolecular catalysis are comprehensively reviewed with regard to active sites, selectivity, as well as host–guest chemistry.

Metal–organic frameworks based on flexible ligands (FL-MOFs): structures and applications

This review presents the recent developments on FL-MOFs, including their structures and applications in gas adsorption, catalysis and proton conduction.

Recent advances on porous homochiral coordination polymers containing amino acid synthons

The recently developed strategies on the designed synthesis of porous homochiral MOCPs based on amino acid residues and their interesting properties are summarized in this highlight.

Rational construction of metal–organic frameworks for heterogeneous catalysis

The recently developed strategies on designed synthesis of porous metal–organic framework catalysts and their interesting catalytic properties are summarized in this short review.

The Chemistry and Applications of Metal-Organic Frameworks

Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

Catalysis at the Organic Ligands

Crystalline metal organic frameworks containing catalytically active organic linkers or ancillary ligands (i.e., catalysts at the organic ligands) are an intriguing sub‐set of heterogeneous catalysts. These catalysts are atomically defined and offer a platform to readily designed single‐site catalysts. The literature encompasses approximately fifty experimental examples from which we highlight a handful of what we perceive to be,key conceptual papers. It is clear that many of the attractive visions for MOF catalysts—including, “multi‐catalyst architectures”, “metal coordination environments that can be achieved in no other ways” and “reactivity‐defining microenvironments”—are starting to be realized.