Formation Of Coordination Polymers Research Articles

New polynuclear compounds based on N-methyliminodipropionic acid: Solution studies, synthesis and X-ray crystal structures

Six new polynuclear coordination compounds based on 3d transition metal ions (Cu(II), Ni(II)) and Zn(II) with the flexible dicarboxylate compound N-methyliminodipropionic acid (H2midp) were prepared and characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. Four of these compounds are 1D coordination polymers, namely [Cu(midp)(H2O)] (1), [Cu3(midp)2(H2O)4](NO3)2·6H2O (2) [Cu3(midp)2(H2O)4](CF3SO3)2·4H2O (3) and [NaZn(Hmidp)2](CF3SO3) (6). The structural analysis revealed that the chain structure of 1 is composed of [Cu(midp)(H2O)] units connected by the free carboxylato oxygen atom of neighbor units, in an alternate fashion. In 2 and 3, on the other hand, there are two [Cu(midp)H2O] units, connected by a central Cu(II) ion coordinating again to the free oxygen atom of the carboxylato groups. The Zn(II) compound is heteronuclear and the complex adopts a 1D cationic polymeric structure with zinc and sodium ions connected by two Hmidp– anions. The two other compounds are dinuclear, [Cu2(Hmidp)2(μ-H2O)2(H2O)2](CF3SO3)2·6H2O (4) and ([Ni2(midp)2(H2O)4] (5). Additionally, a Co(II) and a Cu(II) coordination compound were obtained with the same ligand and characterized by IR spectroscopy, thermal analysis and elemental analysis including metal quantification. For the copper compound the formula [Cu(Hmidp)](ClO4)·3H2O (7) is proposed while for the Co(II) compound (8) the proposed formula is [Co(midp)(H2O)2]. Solution studies of the ligand–M(II) systems (M(II) = Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb) were also carried out in order to help the selection of the best synthetic conditions and also to complement the structural knowledge in the exploration of the potential formation of coordination polymers in these systems.

Competition in formation of stimuli-responsive metallogel and coordination polymers from a single precursor: synthesis, characterization and catalytic application

The synthesis, structure, and catalytic properties of a new 2D crystalline coordination polymer (Zn-CP1) as well as a stable new low molecular weight metallogel (Zn-G1) are reported. Interestingly, both types of materials can be synthesized using the same amino acid based chiral ligand (PV) and Zn2+ ion. Precisely, pure organic solvent (MeOH) prompts gelation while DMF-water medium favours the formation of coordination polymer (CP). Hence, the nature of the solvents and metal counter anion used, play a crucial role in gel formation. Both the CP and gel were characterized by various spectroscopic and analytical techniques such as PXRD, FT-IR, TGA, SEM, and dynamic rheology. Structural analysis of Zn-G1 reveals an entangled spongy-like fibrous network in which spongy patches consist of micro fibres within the matrix of the supramolecular metallogel, while the structural analysis of Zn-CP1 revealed the formation of a 2D sheet-like structure. The Zn-G1 exhibits remarkable stimuli-responsive behaviour towards temperature, mechanical force, and chemicals; however, the Zn-CP1 was found to exhibit promising catalytic activity over Zn-G1 for the conversion of CO2 to cyclic carbonate from various epoxides.

A Coordination-Derived Cerium-Based Amorphous-Crystalline Heterostructure with High Electrocatalytic Oxygen Evolution Activity.

The rational design of heterogeneous catalysts is crucial for achieving optimal physicochemical properties and high electrochemical activity. However, the development of new amorphous-crystalline heterostructures is significantly more challenging than that of the existing crystalline-crystalline heterostructures. To overcome these issues, a coordination-assisted strategy that can help fabricate an amorphous NiO/crystalline NiCeOx (a-NiO/c-NiCeOx ) heterostructure is reported herein. The coordination geometry of the organic ligands plays a pivotal role in permitting the formation of coordination polymers with high Ni contents. This consequently provides an opportunity for enabling the supersaturation of Ni in the NiCeOx structure during annealing, leading to the endogenous spillover of Ni from the depths of NiCeOx to its surface. The resulting heterostructure, featuring strongly coupled amorphous NiO and crystalline NiCeOx , exhibits harmonious interactions in addition to low overpotentials and high catalytic stability in the oxygen evolution reaction (OER). Theoretical calculations prove that the amorphous-crystalline interfaces facilitate charge transfer, which plays a critical role in regulating the local electron density of the Ni sites, thereby promoting the adsorption of oxygen-based intermediates on the Ni sites and lowering the dissociation-related energy barriers. Overall, this study underscores the potential of coordinating different metal ions at the molecular level to advance amorphous-crystalline heterostructure design.

Alloxazine-Based Ligands Appended with Coordinating Groups: Synthesis, Electrochemical Studies, and Formation of Coordination Polymers.

Three new ligands based on the alloxazine core appended with pyridyl coordinating groups have been designed, synthesized, and characterized. The ligands are revealed to be redox-active in DMF solution, as attested to by CV and combined CV/EPR studies. The spin of the reduced species appears to be delocalized on the alloxazine core, as attested to by DFT calculations. The coordination abilities of one of the ligands toward Cu2+ or Ni2+ 3d cations revealed the formation of the first alloxazine-based 3D coordination polymers, presenting strong π-π stacking and substantial cavities. Preliminarily charge/discharge experiments in Li batteries evidence Li+ insertion in such systems.

Stable 2,5‐Dihydroxy‐1,4‐benzoquinone Based Organic Cathode Enabled by Coordination Polymer Formation and Binder Optimization

AbstractOrganic electrode materials are gaining increased attention in energy storage applications, but often encounter challenges such as low capacity and poor cycling stability. This paper explores the utilization of a 1‐D coordination polymer, copper(II)‐2,5‐dihydroxy‐1,4‐benzoquinone (Cu‐DHBQ), as a cathode material for Li‐ion batteries for the first time. Cu‐DHBQ is air‐stable, devoid of coordinated water molecules, and possesses a high theoretical capacity of 266 mAh g−1. With an optimal sodium alginate (SA) binder content of 25 wt%, the Cu‐DHBQ cathode demonstrates a notable initial capacity of 214 mAh g−1 and outstanding cycling stability, retaining 210 mAh g−1 (98% capacity retention) after 200 cycles at a current rate of 100 mA g−1. A comprehensive investigation into the capacity fading mechanisms, the bonding capability of the SA binder, and the interactions between Cu‐DHBQ and SA is conducted using scanning electron microscope (SEM), peel tests, and Fourier transform infrared spectroscopy (FTIR), respectively. Additionally, the electrochemical reaction mechanisms of Cu‐DHBQ are examined using ex situ X‐ray photoelectron spectroscopy (XPS) and FTIR. These findings offer valuable insights into understanding the electrochemical properties of coordination polymers and metal‐organic frameworks based on DHBQ, shedding light on their potential as materials for battery electrodes.

Poly[[(μ3-adamantane-1,3-di-acetato)[μ-N-(pyridin-3-yl)isonicotinamide]-nickel(II)] monohydrate], a layered coordination polymer with triangular (3,6) topology.

The title compound, {[Ni(C14H18O4)(C11H9N3O)]·H2O}n, contains octa-hedrally coordinated NiII ions ligated by 1,3-adamantanedi-acetato (ada) ligands and N-(pyridin-3-yl)isonicotinamide (3-pina) ligands, to form coordination polymer layers with a triangular (3,6) grid topology based on [Ni2(OCO)2] dimeric units. The diperiodic layer motifs stack in an ABAB pattern mediated by C-H⋯O supra-molecular inter-actions between ada ligands and water mol-ecules of crystallization to form the full triperiodic crystal structure of the title compound.

How do pH modifiers modulate the pore environment of polar-neutral bidentate ligated zirconium coordination polymers?

Amino acids are having higher chelating nature, which can be easily complexed with various metal ions. Generally, amino acids are considered to be bidentate ligands with amine and carboxylic functional groups. Among all, l-serine is the neutral polar ligand which consists of a hydroxyl functional group. The l-serine is used as an organic ligand in synthesizing Zr-based Coordination Polymers (CPs). During synthesis, Conc. HCl and NaOH are used as additional pH modifiers. The Ser-Zr CPs are synthesized with and without the additional pH modifiers. The pXRD results show that the Ser-Zr CPs possess a short-range ordered network, i.e., amorphous and having qualitatively coarse surface texture. The FTIR spectrum evidences the bonding between the Zr ion and the l-serine ligand through Zr–N bonding at 644 cm−1. The Ser-Zr CPs synthesized with Conc. HCl possesses enhanced BET surface area, average pore diameter, and total pore volume of 760 m2/g, ∼8.28 nm, and 1.563 cm3/g, respectively. Similarly, the Ser-Zr CPs synthesized with Conc. HCl has multilayer bottle-neck type mesopores. However, the thermal stability of all the Ser-Zr CPs is ∼250 °C. The formation of Ser-Zr CPs and the coordination of serine with Zr are further characterized by ICP-OES and CPMAS NMR spectroscopies. The morphology and crystallinity of the Ser-Zr CPs are studied using a high-resolution transmission electron microscope. The amorphous Ser-Zr CPs can be utilized in applications such as gas adsorption and storage, separation, purification, drug delivery, and many more.

Two-Step Spin Crossover 3D Hofmann-Type Coordination Polymers Including a Functional Group in the Organic Moiety

Spin crossover (SCO) complexes can switch between two electronic states in response to various stimuli. Coordination complexes can be assembled to form coordination polymers or Metal–Organic Frameworks (MOFs), which offer numerous opportunities for developing advanced functional materials with selective binding capabilities for specific analytes. To validate the inclusion of potential receptor groups in 3D SCO MOFs, three new SCO Hofmann-clathrate-like structures were synthesized, including DPBz-Est ( Inorg. Chem. 2013, 52, 4205) as an organic ligand. The introduction of this functional group enabled potential postsynthetic modification, where chemical modifications could be made after the crystal structure was formed. The magnetic performance of the samples revealed a two-step SCO behavior.

Mechanistic Investigation of the Synthesis of Dianionic In-Derived Coordination Polymers.

The mechanism of formation of crystalline coordination polymers is as complex as the architectures themselves. In this Communication, we detail a three-tiered approach using density functional theory (DFT) analysis, synthesis, and in situ Raman spectroscopy to study the formation of coordination polymers. Specifically, the previously reported coordination polymers YCM-22 and YCM-51 containing the [In(CO2R)2X3]2- (X = halogen) molecular building unit (MBU) were investigated. DFT revealed two potential pathways of formation, involving the initial formation of either [InCl4]- or [In(CO2R)Cl3]-. A molecular dimeric In species (8a) containing two [In(CO2R)Cl4]2- centers bridged by 2,5-thiophenedicarboxylic acid was isolated. When a suspension of 8a was treated with a solution of 2,5-thiophenedicarboxylic acid, an isomer of the coordination polymer YCM-22 (denoted as YCM-22') was formed. In situ Raman analysis of the formation of YCM-22 confirms that [InCl4]- forms at the onset of the reaction and that the [In(CO2R)2X3]2- MBU forms at its expense. The totality of the data presented support a mechanism of formation of one-dimensional In-derived coordination polymers and present a roadmap for future investigations into the formation of other crystalline coordination polymers.

Aromatic 1,2-Azaborinin-1-yls as Electron-Withdrawing Anionic Nitrogen Ligands for Main Group Elements.

The 2-aryl-3,4,5,6-tetraphenyl-1,2-azaborinines 1-EMe3 and 2-EMe3 (E=Si, Sn; aryl=Ph (1), Mes (=2,4,6-trimethylphenyl, 2)) were synthesized by ring-expansion of borole precursors with N3 EMe3 -derived nitrenes. Desilylative hydrolysis of 1- and 2-SiMe3 yielded the corresponding N-protonated azaborinines, which were deprotonated with nBuLi or MN(SiMe3 )2 (M=Na, K) to the corresponding group 1 salts, 1-M and 2-M. While the lithium salts crystallized as monomeric Lewis base adducts, the potassium salts formed coordination polymers or oligomers via intramolecular K⋅⋅⋅aryl π interactions. The reaction of 1-M or 2-M with CO2 yielded N-carboxylate salts, which were derivatized by salt metathesis to methyl and silyl esters. Salt metathesis of 1-M or 2-M with methyl triflate, [Cp*BeCl] (Cp*=C5 Me5 ), BBr2 Ar (Ar=Ph, Mes, 2-thienyl), ECl3 (E=B, Al, Ga) and PX3 (X=Cl, Br) afforded the respective group 2, 13 and 15 1,2-azaborinin-2-yl complexes. Salt metathesis of 1-K with BBr3 resulted not only in N-borylation but also Ph-Br exchange between the endocyclic and exocyclic boron atoms. Solution 11 B NMR data suggest that the 1,2-azaborinin-2-yl ligand is similarly electron-withdrawing to a bromide. In the solid state the endocyclic bond length alternation and the twisting of the C4 BN ring increase with the sterics of the substituents at the boron and nitrogen atoms, respectively. Regression analyses revealed that the downfield shift of the endocyclic 11 B NMR resonances is linearly correlated to both the degree of twisting of the C4 BN ring and the tilt angle of the N-substituent. Calculations indicate that the 1,2-azaborinin-1-yl ligand has no sizeable π-donor ability and that the aromaticity of the ring can be subtly tuned by the electronics of the N-substituent.

Amyloid peptide hydrogels via formation of coordination polymers with Ag+ by its core peptide equipped with a C-cysteine.

We report that the core sequence of amyloid β (Aβ) peptide, KLVFF, when equipped with a C-terminal cysteine residue, exhibited an extremely low minimum hydrogelation concentration of 0.05 wt% in the presence of Ag+ in pH 5 buffer, with this concentration 2 orders of magnitude lower than that of the pentapeptide itself. The CD signal of the Ag+-L-KLVFFC hydrogel was observed to be sensitive to the early-stage aggregation of amyloid β peptide.

Versatile fabrication of metal sulfide supraparticles by an in situ decomposition-assembly strategy.

Supraparticles (SPs) are of great importance in both fundamental and applied studies due to their emerging collective properties, synergistic effects, and various applications. Metal sulfide nanomaterials are of vital importance in biomedicine, catalysis, battery materials, and other fields. Herein, an in situ decomposition-assembly strategy for the versatile fabrication of metal sulfide SPs is developed. In the fabrication, cysteine molecules and metal cations first react and form coordination polymers, which are then decomposed by heating to produce small-sized metal sulfide nanocrystals. Driven by elimination of the high surface energy of NCs generated by thermal decomposition and the van der Waals attraction, the resulting nanocrystals in situ self-assemble each other and form SP products. In addition to homogeneous Cu2S, CdS, and ZnS products, the proposed system can even be extended to fabricate hybrid Cu2S/Fe2O3 SPs. Furthermore, the SP size can be easily tuned from 10 to 100 nm by adjusting the proportion of cysteine and metal ions. The SPs not only exhibit various properties including photothermal conversion, fluorescence, and magnetism, depending on their composition, but can also combine these properties by the formation of hybrid structures.

CuI-p-DPA coordination polymer isomers for "turn-on" fluorescence detection of thiophanate-methyl.

Three copper iodide coordination polymer (CuI-p-DPA) isomers were prepared from the fluorescent organic ligand p-DPA and cuprous iodide (CuI) under different solvothermal conditions, which exhibited quenched fluorescence behaviors after forming coordination polymers (CPs). These CuI-p-DPA isomers showed discrepant fluorescence responses to thiophanate-methyl (TM). Among these CuI-p-DPA isomers, α-CuI-p-DPA exhibited the maximum fluorescence enhancement after its incubation with TM in aqueous solution. The fluorescence enhancement mechanism was that TM competed with the ligand p-DPA to coordinate with CuI clusters, and then α-CuI-p-DPA released p-DPA into the solution and induced fluorescence enhancement. The present detection method possesses the advantages of good selectivity, high sensitivity, short response time, and strong anti-interference ability with a linear range of 0.5-100 μM and a detection limit of 0.01 μM. This study not only reveals that the spatial structures of CPs play an important role in the fluorescence response ability, but also provide a new fluorescence signal-on analysis method to rapidly and sensitively determine the pesticide residue for TM.

Machine-Learning-Guided Identification of Coordination Polymer Ligands for Crystallizing Separation of Cs/Sr.

Separation of Cs/Sr is one of many coordination-chemistry-centered processes in the grand scheme of spent nuclear fuel reprocessing, a critical link for a sustainable nuclear energy industry. To deploy a crystallizing Cs/Sr separation technology, we planned to systematically screen and identify candidate ligands that can efficiently and selectively bind to Sr2+ and form coordination polymers. Therefore, we mined the Cambridge Structural Database for characteristic structural information and developed a machine-learning-guided methodology for ligand evaluation. The optimized machine-learning model, correlating the molecular structures of the ligands with the predicted coordinative properties, generated a ranking list of potential compounds for Cs/Sr selective crystallization. The Sr2+ sequestration capability and selectivity over Cs+ of the promising ligands identified (squaric acid and chloranilic acid) were subsequently confirmed experimentally, with commendable performances, corroborating the artificial-intelligence-guided strategy.

Serendipitous discovery of (L)‐valine mediated in situ formation of two‐dimensional coordination polymer by tripodal ligand with transition metals

AbstractA new methodology for 2D coordination polymer formation has been reported by in situ amide bond cleavage of the ligand L at room temperature under a mild condition in the presence of aqueous pyridine. The ligand is formed by the coupling of (L)‐valine with benzene‐1,3,5‐tricarboxylic acid (btcH3). The three amide bonds present on the tripodal ligand, easily break and forms 2D coordination polymer with btc−3 as {[(btc)(py)3(H2O)(Co)1.5].(py)(H2O)2}n (1), {(btc)0.66(py)3(H2O)Ni}n (2), and {[(btc)(py)3Zn1.5](H2O)2}n (3). The tripodal ligand L has been characterized by 1H NMR, 13C NMR, IR, and mass spectra and their corresponding coordination polymers 1, 2, and 3, respectively, have been characterized by single‐crystal X‐ray diffraction and thermogravimetric analysis.

Metal and bis(pyridyl)-bis(amide) ligands – tuned three new nickel(II)/copper(II) coordination polymers: Syntheses, structures and properties

Three new Ni(II)/Cu(II) coordination polymers (CPs), [Ni(L1)1.5(HBTC)(H2O)] (1), [Ni(L2)2(HBTC)]·2H2O (2) and [Cu2(L2)0.5(BTC)(μ3-OH)]·2H2O (3) {H3BTC = benzene-1,3,5-tricarboxylic acid, L1 = (E)-4,4′-(ethene-1,2-diyl)bis[N-(pyridin-3-yl)benzamide] and L2 = (E)-4,4′-(diazene-1,2-diyl)bis[N-(pyridin-3-yl)benzamide]}, were prepared under hydrothermal and solvothermal conditions by regulating different metals and ligands. The structures of CPs 1–3 were characterized by single crystal X-ray diffraction analyses, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD). CP1 displays a 4-connected 3D topological structure based on [Ni(HBTC)]n chains and [Ni(L1)1.5]n chains. When L2 was used, CP2 demonstrates a 1D chain structure. CP3 is a 3D metal–organic network with the binodal (3,8)-connected {4·62}2{42·622·7·83} topology constructed from {Cu4} clusters and L2 ligands. The photocatalytic properties and electrochemical behaviors of CPs 1–3 were explored. The effect of solvent on the formation of the title CPs as well as the influence of the central metals and ligands on the structures and properties are discussed.

Syntheses, crystal structures, and luminescence properties of three cadmium coordination polymers assembled from a semi-rigid tetracarboxylate ligand

Crystal engineering is considerably useful in the preparation of functional coordination polymers. In the present study, a new semi-rigid tetracarboxylate, 4,5-bis(4-carboxyphenoxy)phthalic acid (H4L), was designed and applied for assembling metal coordination polymers. Self-assembling process involving Cd(II) metal ions, H4L and 4,4′-bipyridine (4,4′-bpy), (E)-1,2-bis(pyridin-4-yl)ethane (bpe) or 1,4-bis(1-imidazolyl)benzene (bib) resulted into the formation of coordination polymers, including [Cd2(L)(4,4′-bpy)1.5(H2O)]n·(H2O)n (1), [Cd2(L)(bpe)1.5(H2O)]n·(H2O)3.5n (2), and [Cd2(L)(bib)1.5]n·(H2O)n (3). Through X-ray single crystal diffraction analysis, the three compounds 1–3 were found to exhibit isostructural three-dimensional polymeric structures composed of two-dimensional secondary layers pillared by different rod-like N-donor ligands. Compared with the uncoordinated H4L exhibiting a symmetric crystal structure, the molecular configurations of L4− in 1–3 were tuned due to the complexation of cadmium ion and the introduction of different N-donors. Additionally, the coordination geometries of cadmium ions and luminescence properties in compounds 1–3 were finely tuned due to the introduction of different lengths of rod-like ligands. The thermostability and luminescence properties of compounds 1–3 were determined. The present results provide further understanding of the crystal engineering of semi-rigid ligands to a certain extent.

Rational and site-selective formation of coordination polymers consisting of d10 coinage metal ions with thiolate ligands using a metal ion-doped polymer substrate.

Here, we report an interfacial approach for fabricating coordination polymers (CPs) consisting of d10 coinage metal ions with thiolate ligands on a polymer substrate. It was found that CPs were selectively formed on the polymer substrate, resulting in the formation of CP-based thin films. In addition, utilizing a mixed metal ion-doped polymer substrate leads to the formation of mixed-metal CP-based films.

Detection of Cadmium-related ions by MALDI TOF mass spectrometry correlates with physicochemical properties of Cadmium/matrix adducts

Metal acetate complexes are highly interesting in designing and synthesizing metal–organic frameworks, which have potential applications in gas storage, molecular sieves, ion exchange, and catalysis. Cadmium is well recognized as an industrial pollutant and a food contaminant that severely affects human health. For these reasons, the detection and analysis of Cd are of great interest. A major challenge in studying cadmium compounds' structure is that Cd2+ can have a wide range of coordination numbers and diverse geometries. (MA)LDI is extremely useful for detecting Cd(OAc)2·2H2O and investigating Cd's complex and flexible nature. We applied LDI to detect and characterize the Cd-related clusters and MALDI approach to investigate the Cd(OAc)2x2H2O reactivity and detectability with the five different organic matrices. The results revealed that in the solid-state Cd(OAc)2x2H2O tend to form coordination polymers, and in the presence of coordinating ligands (matrix molecules) form smaller complexes. In addition, the correlation between Cd-related LOD and matrix features was observed and discussed, indicating that the LODs of this analyte strongly depend on the optical absorption of the matrix-analyte adduct.

Coordination Polymers Constructed from Pyrogallol[4]arene-Assembled Metal–Organic Nanocapsules

Coordination polymers, commonly known as infinite crystalline lattices, are versatile networks and have diverse potential applications in the fields of gas storage, molecular separation, catalysis, optics, and drug delivery, among other areas. Secondary building blocks, mainly incorporating rigid polydentate organic linkers and metal ions or clusters, are commonly employed to construct coordination polymers. Recently, novel building blocks such as coordination polyhedra have been utilized as metal nodes to fabricate coordination polymers. Benefiting from the rigid porous structure of the coordination polyhedron, prefabricated designer "pores" can be incorporated in this type of coordinate polymer. In this Account, coordination polymers built by pyrogallol[4]arene-assembled metal-organic nanocapsules are summarized. This class of metal-organic nanocapsule possesses the following advantages that make them excellent candidates in the construction of coordination polymers: (i) Various geometrical shapes with different volumes of the inner cavities can be obtained from these capsules. Among them, the two main categories illustrated are dimeric and hexameric capsules, which comprise two and six pyrogallol[4]arenes units, respectively. (ii) A wide range of possible metal ions ranging from main group metals to transition metals and even lanthanides have been demonstrated to seam the capsules. Therefore, these coordination polymers can be endowed with fascinating functionalities such as magnetism, semiconductivity, luminescence, and radioactivity. (iii) Up to 24 metal ions have been successfully embedded on the surface of the nanocapsule, each a potential reaction site in the construction of coordination polymers, opening up pathways for the formation of multidimensional frameworks.In this Account, we focus primarily on the synthesis and the structural information on pyrogallol[4]arene-derived coordination polymers. Coordination polymers can be formed by introducing linkers with two coordination sites, using pyrogallol[4]arenes with coordination sites on the tail, or even via metal ions cross-linking with each other. Machine learning was recently developed to help us predict and screen the structures of the coordination polymers. With single crystal analysis in hand, detailed structural information provides a molecular-level perspective. Significantly, following the formation of coordination polymers, the overall shape and structure of the discrete metal-organic nanocapsules remains essentially unchanged, with full retention of the prefabricated pores. If a rigid linker is used to connect capsules, more than one lattice void with different volumes can be found within the framework. Thus, molecules with different sizes could potentially be encapsulated within these coordination polymers. In addition, flexible ligands can also be employed as linkers. For example, polymers have been employed as large linkers that transform the crystalline coordination polymers into polymer matrices, paving the way toward the synthesis of advanced functional materials. Overall, coordination polymers constructed with pyrogallol[4]arene-assembled metal-organic nanocapsules show wide diversity and tunability in structure and fascinating properties, as well as the promise of built-in functionality in the future.