Metal-organic complexes assembled from coordinative interactions are known to be able to display a wide range of photoluminescent behaviors benefiting from an extensive number of metal ions, organic linkers, and inclusion guests, depending on the multifaceted nature of their chemical structures and photophysical properties. In the past two decades, the white-light-emitting (WLE) and photoluminescent color-tuning (PLCT) materials based on the single-phase metal-organic coordination assemblies have merited particular attention and gained substantial advances. In this review, we give an overview of recent progress in this field, placing emphasis on the WLE and PLCT properties realized in the single-phase materials, which covers the origin, generation, and manipulation of different types of photoluminescence (PL) derived from ligand-centered (LC), metal/cluster-centered (MC or CC), excimer/exciplex-based (EX), metal-to-ligand or ligand-to-metal charge-transfer-based (MLCT or LMCT), or guest-included emissions. The coordination assemblies in this topic can be generally classified into three categories [(1) mono/homometallic coordination assemblies based on main group (s,p-block), transition (d-block), or lanthanide (f-block) metal centers, (2) s/p-f-, d-f-, or f-f-type heterometallic coordination assemblies, and (3) guest-included coordination assemblies] for which WLE and PLCT properties can be achieved by virtue of either a wide-band/overlapped emission covering the whole visible spectrum from a single emitting center or a combination of complementary color emissions from multiple emitting centers/origins. Some state-of-the-art assembly methods and successful design models relevant to the above three categories are elaborated to demonstrate how to achieve efficient and controllable white-light emission in a single-phase material through a tunable PL approach. Potential applications in the fields of lighting and displaying, sensing and detecting, and barcoding and patterning are surveyed, and at the end, possible prospects and challenges for future development along this line are proposed.

Single-Phase White-Light-Emitting and Photoluminescent Color-Tuning Coordination Assemblies

Metal-organic frameworks represent the ultimate chemical platform on which to develop a new generation of designer magnets. In contrast to the inorganic solids that have dominated permanent magnet technology for decades, metal-organic frameworks offer numerous advantages, most notably the nearly infinite chemical space through which to synthesize predesigned and tunable structures with controllable properties. Moreover, the presence of a rigid, crystalline structure based on organic linkers enables the potential for permanent porosity and postsynthetic chemical modification of the inorganic and organic components. Despite these attributes, the realization of metal-organic magnets with high ordering temperatures represents a formidable challenge, owing largely to the typically weak magnetic exchange coupling mediated through organic linkers. Nevertheless, recent years have seen a number of exciting advances involving frameworks based on a wide range of metal ions and organic linkers. This review provides a survey of structurally characterized metal-organic frameworks that have been shown to exhibit magnetic order. Section 1 outlines the need for new magnets and the potential role of metal-organic frameworks toward that end, and it briefly introduces the classes of magnets and the experimental methods used to characterize them. Section 2 describes early milestones and key advances in metal-organic magnet research that laid the foundation for structurally characterized metal-organic framework magnets. Sections 3 and 4 then outline the literature of metal-organic framework magnets based on diamagnetic and radical organic linkers, respectively. Finally, Section 5 concludes with some potential strategies for increasing the ordering temperatures of metal-organic framework magnets while maintaining structural integrity and additional function.

Metal-Organic Framework Magnets.

Three-dimensional porous coordination polymers, which are known as metal–organic frameworks (MOFs), have drawn considerable attention owing to their properties, such as highly crystalline and ordered structures, inorganic–organic-hybrid nature, tunability of chemical functionality, high porosity and surface area and moderate-to-high stability. Due to these properties, MOFs are applied extensively as probes for the detection of large varieties of organic molecules. In this line, different MOF-based instrumental and material-based methods along with different strategies have been developed to study and extend our information about the capabilities of MOFs as sensing probes for the detection of organic molecules as well as improving and developing their detection limits, selectivity and sensitivity toward specific analytes. Considering these points, we have presented and classified the content of this review based on the chemical structures of organic analytes in three categories, including (I) nitroaromatic explosives and energetic materials, (II) small organic molecules, such as solvents and volatile organic compounds, and (III) organic amines. For each group of these analytes, different material and instrumental methods using MOFs have been explained, with illustrations of remarkable examples. Finally, we compare the methods for the detection of each group of analytes and discuss which instrumentation is more effective for each group of analytes.

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Sensing organic analytes by metal–organic frameworks: a new way of considering the topic

Bipyridinium derivative-based coordination polymers: From synthesis to materials applications

Luminescent metal–organic frameworks and coordination polymers as alternative phosphors for energy efficient lighting devices

Advancement in explosive systems toward miniaturization and enhanced safety has prompted the development of primary explosives with powerful detonation performance and relatively low sensitivities. Energetic coordination polymers (ECPs) as a new type of energetic materials have attracted wide attention. However, regulating the energetic characters of ECPs and establishing the relationship between structure and energetic property remains great challenges. In this study, two isomorphic 2D π-stacked solvent-free coordination polymers, [M(N3)2(atrz)]n (M = Co 1, Cd 2; atrz = 4,4′-azo-1,2,4-triazole), were hydrothermally prepared and structurally characterized by X-ray diffraction. The two compounds exhibit reliable stabilities, remarkable positive enthalpies of formation, and prominent heats of detonation. The enthalpy of formation of 1 is 4.21 kJ·g–1, which is higher than those of all hitherto known primary explosives. Repulsive steric clashes between the sensitive azide ions in 1 and 2 influence the mechani...

Coordination Polymerization of Metal Azides and Powerful Nitrogen-Rich Ligand toward Primary Explosives with Excellent Energetic Performances

Primary explosives with powerful and reliable stabilities have attractive applications in the field of military and civilian technologies. In this work, four two-dimensional, solvent-free metal azi...

Substitution of Nitrogen-Rich Linkers with Insensitive Linkers in Azide-Based Energetic Coordination Polymers toward Safe Energetic Materials

Solid-state X-ray scintillators are widely applied in medical imaging and space exploration. However, it is still a great challenge to probe into the intrinsic nature of scintillating behaviour due to the ambiguous structure–function relationship. Herein, four structure-defined X-ray scintillating Pb(II)-based metal–organic frameworks (SMOFs) were successfully obtained under solvothermal conditions, [Pb(1,4-ndc)(DMF)]n (SMOF-1), [Pb(1,4-ndc)(DMA)]n (SMOF-2), [Pb2(2,6-ndc)2(H2O)]n·nDMF (SMOF-3) and [Pb4(2,6-ndc)3Cl2]n (SMOF-4), where 1,4-H2ndc = 1,4-naphthalene dicarboxylate, 2,6-H2ndc = 2,6-naphthalene dicarboxylate, DMF = N,N-dimethylformamide, and DMA = N,N-dimethylacetamide. SMOFs 1–4 show scintillating signals under X-rays triggered by a highly purified tungsten target. Compared with SMOFs 1–3, SMOF-4 exhibits excellent scintillating performance owing to its solvent-free and denser structure, which favours more efficient conversion ability of X-rays to visible light. X-ray stimulated luminescence (XSL) spectra present multiple emission peaks, which is further confirmed by wavelength-dependent luminescence spectra under UV-Vis light, and density of state and DFT calculations. The synergistic effects of heavy metal Pb(II) centres as effective X-ray absorbers and organic ligands as luminescent motifs endow these Pb(II)-based MOFs with application prospects in X-ray detection.

Efficient X-ray scintillating lead(ii)-based MOFs derived from rigid luminescent naphthalene motifs.

Energetic azide-based coordination polymers: Sensitivity tuning through diverse structural motifs

Nitrogen-rich high density metal–organic frameworks (MOFs) can be used as a new type of energetic materials. The energetic MOFs provide a new method to reconcile contradiction between high energy a...

Jian-Gang Xu

Papers

Coordination Polymerization of Metal Azides and Powerful Nitrogen-Rich Ligand toward Primary Explosives with Excellent Energetic Performances

Substitution of Nitrogen-Rich Linkers with Insensitive Linkers in Azide-Based Energetic Coordination Polymers toward Safe Energetic Materials

Efficient X-ray scintillating lead(ii)-based MOFs derived from rigid luminescent naphthalene motifs.

Energetic azide-based coordination polymers: Sensitivity tuning through diverse structural motifs

Framework-Interpenetrated Nitrogen-Rich Zn(II) Metal–Organic Frameworks for Energetic Materials