Isogonal embeddings of interwoven and self-entangled honeycomb (hcb) nets and related interpenetrating primitive cubic (pcu) nets

Two- and three-periodic vertex-transitive (isogonal) piecewise-linear embeddings of self-entangled and interwoven honeycomb nets are described. The infinite families with trigonal symmetry and edge transitivity (isotoxal) are particularly interesting as they have the Borromean property that no two nets are directly linked. These also lead directly to infinite families of interpenetrating primitive cubic nets (pcu) that are also vertex- and edge-transitive and have embeddings with 90° angles between edges.

Interpenetration Phenomena via Anion Template Effects in Fe(II) and Co(II) Coordination Networks with a Bis-(1,2,4-triazole) Ligand

Seven new coordination networks, [Fe(tbbt)3](BF4)2 (1), [Co(tbbt)3](BF4)2 (2), [Fe(tbbt)3](ClO4)2 (3), [Co(tbbt)3](ClO4)2 (4), [Fe(NCS)2(tbbt)2] (5), [Co(NCS)2(tbbt)2] (6), and [Fe(H2O)2(tbbt)2]Br2·2H2O (7), were synthesized with the linker 1,1'-(trans-2-butene-1,4-diyl)bis-1,2,4-triazole (tbbt) and structurally investigated. The structure of complexes 1-4 is composed of three interpenetrating, symmetry-related 3D networks. Each individual 3D network forms a primitive, nearly cubic lattice (pcu) with BF4- or ClO4- anions present in the interstitial spaces. The structure of compounds 5 and 6 is composed of two-dimensional sql layers, which are parallel to each other in the AB stacking type. These layers are interpenetrated by one-dimensional chains, both having the same formula unit, [M(NCS)2(tbbt)2] (M = Fe, Co). The structure of compound 7 consists of parallel, two-dimensional sql layers in the ABCD stacking type. The interpenetration in 1-6 is not controlled by π-π-interactions between the triazole rings or C=C bonds, as could have been expected, but by (triazole)C-H⋯F4B, C-H⋯O4Cl, and C-H⋯SCN anion hydrogen bonds, which suggests a template effect of the respective non-coordinated or coordinated anion for the interpenetration. In 7, the (triazole)C-H⋯Br anion interactions are supplemented by O-H⋯O and O-H⋯Br hydrogen bonds involving the aqua ligand and crystal water molecules. It is evident that the coordinated and non-coordinated anions play an essential role in the formation of the networks and guide the interpenetration. All iron(II) coordination networks are colorless, off-white to yellow-orange, and have the metal ions in the high-spin state down to 77 K. Compound 5 stays in the high spin state even at temperatures down to 10 K.

Self-Assembly of a Two-Dimensional Coordination Polymer Based on Silver and Lanthanide Tetrakis-Acylpyrazolonates: An Efficient New Strategy for Suppressing Ligand-to-Metal Charge Transfer Quenching of Europium Luminescence

A new strategy for the easy polymerization of anionic [Ln(Q^cy)₄]^- (HQ^cy-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) into two-dimensional layers of [AgLn(Q^cy)₄]_n (Ln = Sm, Eu, Gd, Tb and Dy) is proposed by binding the single molecular anions [Ln(Q^cy)₄]^- to silver cations through the coordination of the pyridinic nitrogen atoms of the pyrazolonate rings. The luminescent properties of [AgLn(Q^cy)₄]_n have been studied in detail, and it was shown that the previously described low photoluminescence quantum yield (PLQY) of [Eu(Q^cy)₄]^- is due to Ligand-To-Metal Charge Transfer (LMCT) quenching, which is effectively suppressed in the heterometallic [AgEu(Q^cy)₄]_n polymer. Sensibilization coefficients for H₃O[Eu(Q^cy)₄], [AgEu(Q^cy)₄]_n, and H₃O[Sm(Q^cy)₄] complexes (n ≈ 1) were estimated via theoretical analysis (also by using Judd-Ofelt theory for Sm³⁺) and PLQY measurements.

Symmetric Tangling of Honeycomb Networks

Symmetric, elegantly entangled structures are a curious mathematical construction that has found their way into the heart of the chemistry lab and the toolbox of constructive geometry. Of particular interest are those structures—knots, links and weavings—which are composed locally of simple twisted strands and are globally symmetric. This paper considers the symmetric tangling of multiple 2-periodic honeycomb networks. We do this using a constructive methodology borrowing elements of graph theory, low-dimensional topology and geometry. The result is a wide-ranging enumeration of symmetric tangled honeycomb networks, providing a foundation for their exploration in both the chemistry lab and the geometers toolbox.

Acetylenedicarboxylate as a linker in the engineering of coordination polymers and metal-organic frameworks: challenges and potential

Despite its simplicity as a short and rod-like linear linker, acetylenedicarboxylate (ADC) has for a long time been somewhat overlooked in the engineering of coordination polymers (CPs) and especially in the construction of porous metal-organic frameworks (MOFs). This situation seems to be stemming from the thermosensitivity of the free acid (H₂ADC) precursor and its dicarboxylate, which makes the synthesis of their CP- and MOF-derivatives, as well as the evacuation of guest molecules from their pores, challenging. However, an increasing number of publications dealing with the synthesis, structural characterization and properties of ADC-based CPs and MOFs, disclose ways to tackle this obstacle. In this regard, using mostly room temperature solution synthesis or mechanochemical synthesis, and very rarely solvothermal synthesis, the ADC linker has successfully been used to form one-, two-, and three-dimensional CPs with metal cations from almost all groups of the periodic table of the elements, whereby its carboxylate groups adopt mainly all types of known coordination modes. ADC-based CPs feature properties, including negative thermal expansion, formation of non-centrosymmetric networks, long-range magnetic ordering, and solid-state polymerization. The first ADC-based microporous MOFs were obtained with Ce(IV), Hf(IV) and Zr(IV), in which the presence of the -CC- triple-bond within their backbone results in high hydrophilicity, high CO₂ adsorption capacity and enthalpy, as well as the uptake of halogen vapors. This discloses the potential of ADC-MOFs for gas storage/separation and water adsorption-based applications. Furthermore, H₂ADC/ADC was discovered to undergo facile in situ hydrohalogenation to yield halogen-functionalized fumarate-based CPs/MOFs. This review surveys investigations on ADC-based coordination polymers and metal-organic frameworks, and is intended to stimulate interest on this linker in chemists working in the fields of crystal chemistry or materials science.

Synthesis and crystal structure of bis[trans-diaqua(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)nickel(II)] trans-(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)bis[4,4′,4′′-(1,3,5-trimethylbenzene-2,4,6-triyl)tris(hydrogen phenylphosphonato-κO)]nickel(II) decahydrate

The components of the title compound, [Ni(C10H24N4)(H2O)2]2[Ni(C10H24N4)(C27H24O9P3)2]·10H2O are two centrosymmetric [Ni(C10H24N4)(H2O)2]2+ dications, a centrosymmetric [Ni(C10H24N4)(C27H24O9P3)2]4− tetra-anion and five crystallographically unique water molecules of crystallization. All of the nickel ions are coordinated by the four secondary N atoms of the macrocyclic cyclam ligands, which adopt the most energetically stable trans-III conformation, and the mutually trans O atoms of either water molecules in the cations or the phosphonate groups in the anion in a tetragonally distorted NiN4O2 octahedral coordination geometry. Strong O—H...O hydrogen bonds between the protonated and the non-protonated phosphonate O atoms of neighboring anions result in the formation of layers oriented parallel to the bc plane, which are linked into a three-dimensional network by virtue of numerous N—H...O and O—H...O hydrogen bonds arising from the sec-NH groups of the macrocycles, phosphonate O atoms and coordinated and non-coordinated water molecules.

Contrasting Networks and Entanglements in Uranyl Ion Complexes with Adipic and trans,trans-Muconic Acids

Adipic (hexane-1,6-dicarboxylic, adpH₂) and trans,trans-muconic (trans,trans-hexa-2,4-diene-1,6-dicarboxylic, mucH₂) acids have been reacted with uranyl cations under solvo-hydrothermal conditions, yielding nine homo- or heterometallic complexes displaying in their crystal structure the effects of the different flexibility of the ligands. The complexes [PPh₄]₂[(UO₂)₂(adp)₃] (1) and [Ni(bipy)₃][(UO₂)₂(muc)₃]·5H₂O (2), where bipy is 2,2'-bipyridine, crystallize as diperiodic networks with the hcb topology, the layers being strongly puckered or quasiplanar, respectively. Whereas [(UO₂)₂(adp)₃Ni(cyclam)]·2H₂O (3), where cyclam is 1,4,8,11-tetraazacyclotetradecane, crystallizes as a diperiodic network, [(UO₂)₂(muc)₃Ni(cyclam)]·2H₂O (4) is a triperiodic framework in which the Ni^II cations are introduced as pillars within a uranyl-muc^2- framework with the mog topology. [UO₂(adp)(HCOO)₂Cu(R,S-Me₆cyclam)]·2H₂O (5), where R,S-Me₆cyclam is 7(R),14(S)-5,5,7,12,12,14-hexamethylcyclam, is a diperiodic assembly with the sql topology, and it crystallizes together with [H₂NMe₂]₂[(UO₂)₂(adp)₃] (6), a highly corrugated hcb network with a square-wave profile, which displays 3-fold parallel interpenetration. In contrast, [(UO₂)₃(muc)₂(O)₂Cu(R,S-Me₆cyclam)] (7) is a diperiodic assembly containing hexanuclear, μ₃-oxido-bridged secondary building units which are the nodes of a network with the hxl topology. The two related complexes [PPh₃Me]₂[(UO₂)₂(adp)₃]·4H₂O (8) and [PPh₃Me]₂[(UO₂)₂(muc)₃]·H₂O (9) crystallize as hcb networks, but their different shapes, undulated or quasiplanar, respectively, result in different entanglements, 2-fold parallel interpenetration in 8 and 2-fold inclined 2D → 3D polycatenation in 9.

Design and synthesis of new luminescent coordination networks of topology showing the highest degrees of interpenetration

The highest degree of interpenetration reported so far of 7- and 8-fold is realized in two luminescent sql 2D networks by self-assembly of a new nanometric-sized ligand with Ag(i) salts.

Metal-organic framework structures of fused hexagonal motifs with cuprophilic interactions of a triangular Cu(I)3(pyrazolate-benzoate) metallo-linker

The reaction of the N,O-heteroditopic bifunctional ligand 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoic acid (H2mpba) with Cu(NO3)2·2.5H2O and Zn(NO3)2·4H2O or Zn(CH3COO)2·2H2O in N,N-dimethylformamide (DMF) results in concomitant formation of three bimetallic metal-organic frameworks (MOFs) with...

A series of entangled MOFs constructed from flexible dipyridyl piperazine and rigid dicarboxylate: interpenetration, self-penetration, and polycatenation

By employing a flexible dipyridyl piperazine and a rigid linear dicarboxylate, four MOFs with different entangled structures involving a 3D inclined polycatenane and a 3D self-penetrated framework incorporating cyclic [3]catenane were isolated.

Topological transformations in metal–organic frameworks: a prospective design route?

We apply a topological approach based on the underlying net and transformation pattern concepts as well as on the ‘supernet–subnet’ formalism to uncover mechanisms of solid-state transformations in coordination polymers and metal–organic frameworks.

On Borromean links and related structures

The creation of knotted, woven and linked molecular structures is an exciting and growing field in synthetic chemistry. Presented here is a description of an extended family of structures related to the classical `Borromean rings', in which no two rings are directly linked. These structures may serve as templates for the designed synthesis of Borromean polycatenanes. Links of n components in which no two are directly linked are termed `n-Borromean' [Liang & Mislow (1994). J. Math. Chem. 16, 27-35]. In the classic Borromean rings the components are three rings (closed loops). More generally, they may be a finite number of periodic objects such as graphs (nets), or sets of strings related by translations as in periodic chain mail. It has been shown [Chamberland & Herman (2015). Math. Intelligencer, 37, 20-25] that the linking patterns can be described by complete directed graphs (known as tournaments) and those up to 13 vertices that are vertex-transitive are enumerated. In turn, these lead to ring-transitive (isonemal) n-Borromean rings. Optimal piecewise-linear embeddings of such structures are given in their highest-symmetry point groups. In particular, isonemal embeddings with rotoinversion symmetry are described for three, five, six, seven, nine, ten, 11, 13 and 14 rings. Piecewise-linear embeddings are also given of isonemal 1- and 2-periodic polycatenanes (chains and chain mail) in their highest-symmetry setting. Also the linking of n-Borromean sets of interleaved honeycomb nets is described.

Isotopy classes for 3-periodic net embeddings

Entangled embedded periodic nets and crystal frameworks are defined, along with their dimension type, homogeneity type, adjacency depth and periodic isotopy type. Periodic isotopy classifications are obtained for various families of embedded nets with small quotient graphs. The 25 periodic isotopy classes of depth-1 embedded nets with a single-vertex quotient graph are enumerated. Additionally, a classification is given of embeddings of n-fold copies of pcu with all connected components in a parallel orientation and n vertices in a repeat unit, as well as demonstrations of their maximal symmetry periodic isotopes. The methodology of linear graph knots on the flat 3-torus [0,1)3 is introduced. These graph knots, with linear edges, are spatial embeddings of the labelled quotient graphs of an embedded net which are associated with its periodicity bases.

Record Complexity in the Polycatenation of Three Porous Hydrogen-Bonded Organic Frameworks with Stepwise Adsorption Behaviors

Hydrogen-bonded organic frameworks (HOFs) show great potential in many applications, but few structure-property correlations have been explored in this field. In this work, we report that self-assembly of a rigid and planar ligand gives rise to flat hexagonal honeycomb motifs which are extended into undulated two-dimensional (2D) layers and finally generate three polycatenated HOFs with record complexity. This kind of undulation is absent in the 2D layers built from a very similar but nonplanar ligand, indicating that a slight torsion of ligand produces overwhelming structural change. This change delivers materials with unique stepwise adsorption behaviors under a certain pressure originating from the movement between mutually interwoven hexagonal networks. Meanwhile, high chemical stability, phase transformation, and preferential adsorption of aromatic compounds were observed in these HOFs. The results presented in this work would help us to understand the self-assembly behaviors of HOFs and shed light on the rational design of HOF materials for practical applications.

Crystallographic descriptions of regular 2-periodic weavings of threads, loops and nets

Piecewise linear descriptions are presented of weavings of threads, loops and 2-periodic nets. Crystallographic data are provided for regular structures, defined as those with one kind (symmetry-related) of vertex (corner) and edge (stick). These include infinite families of biaxial thread weaves, interwoven square lattices (sql), honeycomb (hcb) nets, and tetragonal and hexagonal polycatenanes.

Reversible photo/thermal solid-state transformation of a coordination polymer

A 2D coordination polymer, 1, was synthesized, characterized, and investigated with single-crystal-to-single-crystal photoreaction and thermal pyrolysis.

Tubelike Uranyl-Phenylenediacetate Assemblies from Screening of Ligand Isomers and Structure-Directing Counterions

Reaction of 1,2-, 1,3-, or 1,4-phenylenediacetic acids (1,2-, 1,3-, or 1,4-H₂PDA) with uranyl ions under solvo-hydrothermal conditions and in the presence of [M(L) _n] ^q+ cations, in which M = transition metal cation, L = 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen), n = 2 or 3, and q = 1 or 2, gave 10 complexes which have been crystallographically characterized. The diacetate ligands are bis-chelating and the uranyl cations are tris-chelated in all cases. [UO₂(1,2-PDA)₂Zn(phen)₂]·2H₂O (1) and [UO₂(1,4-PDA)₂Mn(bipy)₂]·H₂O (2) are heterometallic, neutral one-dimensional (1D) coordination polymers in which the carboxylate-coordinated 3d block metal cation is either decorating only (1) or participates in polymer building (2). [Zn(phen)₃][(UO₂)₂(1,3-PDA)₃] (3) and [Ni(phen)₃][(UO₂)₂(1,4-PDA)₃]·H₂O (4), with separate counterions, crystallize as anionic two-dimensional (2D) networks, as does [Cu(bipy)₂][H₂NMe₂][(UO₂)₂(1,4-PDA)₃] (5), which displays parallel 2D interpenetration. The complex [Zn(phen)₃][(UO₂)₂(1,2-PDA)₃]·7H₂O (6) crystallizes as a ladderlike, slightly inflated ribbon. The same topology is found in [Zn(bipy)₃][(UO₂)₂(1,3-PDA)₃] (7), but the larger separation between coordination sites and the coexistence of curved and divergent ligand conformations produce a tubelike assembly. An analogous but more regular and spacious tubular geometry is found in [M(bipy)₃][(UO₂)₂(1,4-PDA)₃], with M = Co (8) or Ni (9), and {Λ-[Ru(bipy)₃]}[(UO₂)₂(1,4-PDA)₃] (10). The disordered counterions in 8 and 9 are replaced by well-ordered, enantiomerically pure chiral counterions in 10. The tubular assemblies formed in 7-10 are characterized by an oblong section and the presence of gaps in the walls, which enable the inclusion of two rows of counterions in the cavity.

Solvent-directed control over the topology of entanglement in square lattice (sql) coordination networks

We report herein that the mode of entanglement in square lattice, sql, coordination networks formed by an extended bis-imidazole ligand, L, can be controlled by the solvent used during solvothermal synthesis.

Structural, thermal and topological characterization of coordination networks containing flexible aminocarboxylate ligands with a central biphenylene scaffold

Flexible aminocarboxylate ligands have been used to construct coordination networks containing Zr, Zn and Cd featured by different dimensionalities and topologies.

Variation of topologies and entanglements in metal–organic frameworks with mixed tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide and dicarboxylate ligands

Six metal–organic frameworks with variation of topologies and entanglements have been successfully synthesized with mixed tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide and dicarboxylate ligands.

Distinguishing Metal-Organic Frameworks

We consider two metal-organic frameworks as identical if they share the same bond network respecting the atom types. An algorithm is presented that decides whether two metal-organic frameworks are the same. It is based on distinguishing structures by comparing a set of descriptors that is obtained from the bond network. We demonstrate our algorithm by analyzing the CoRe MOF database of DFT optimized structures with DDEC partial atomic charges using the program package ToposPro.

A new CdII coordination polymer with a self-penetrating architecture induced by the molecular conformation of a rigid bithiophene ligand

The design and synthesis of coordination polymers with a self-penetrating architecture has attracted much interest not only due to their interesting structures but also due to their potential applications. 5,5'-Bis(pyridin-4-yl)-2,2'-bithiophene (bpbp), as a conjugated bithiophene ligand, can exhibit trans and cis conformations and this can lead to the construction of a self-penetrating architecture. In addition, the semi-rigid ancillary ligand 4,4'-oxybis(benzoic acid) (H₂oba) can adopt different coordination modes, resulting in coordination polymers with high-dimensional skeletons. A new Cd^II coordination polymer based on mixed ligands, namely poly[diaquapentakis[μ-5,5'-bis(pyridin-4-yl)-2,2'-bithiophene-κ²N:N']bis(nitrato-κ²O,O')tetrakis(μ₃-4,4'-oxydibenzoato)-κ¹⁰O:O,O':O'',O''';κ⁶O:O':O''-pentacadmium(II)], [Cd₅(C₁₄H₁₄O₅)₄(NO₃)₂(C₁₈H₁₂N₂S₂)₅(H₂O)₂]_n, (I), has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction indicates that there are three crystallographically independent Cd^II cations, three bpbp ligands, two deprotonated oba^2- ligands, one nitrate ligand and one coordinated water molecule in the asymmetric unit. One Cd^II centre is seven-coordinated, exhibiting a distorted {CdN₂O₅} pentagonal bipyramidal geometry, while the other two Cd centres are both six-coordinated, showing slightly distorted {CdN₂O₄} octahedral geometries. The most interesting feature is the co-existence of trans and cis conformations in a single net, allowing structural interpenetration via self-threading and yet the expected self-penetrating structure was obtained. Topological analysis shows that the whole three-dimensional framework can be classified as a 3-nodal (4,6,6)-c net with Schläfli symbol {6¹³.8²}₂{6⁶}, which is a new topology. Furthermore, the luminescence properties of (I) were examined in the solid state at room temperature.

Structural diversity of six metal–organic frameworks from a rigid bisimidazole ligand and their adsorption of organic dyes

Six entangled coordination polymers from a bisimidazole ligand and versatile carboxylate acids have been synthesized and structurally characterized. Their adsorption behaviors to organic dyes have also been evaluated.

Structural Consequences of 1,4-Cyclohexanedicarboxylate Cis/Trans Isomerism in Uranyl Ion Complexes: From Molecular Species to 2D and 3D Entangled Nets

trans-1,4-Cyclohexanedicarboxylic acid (t-1,4-chdcH₂) or the commercially available mixture of the cis and trans isomers (c,t-1,4-chdcH₂) has been used in the synthesis of a series of 14 uranyl ion complexes, all obtained under solvohydrothermal conditions, some in the presence of additional metal cations and/or 2,2'-bipyridine (bipy). With its two isomeric forms having very different shapes and its great sensitivity to the experimental conditions, 1,4-chdc^2- appears to be suitable for the synthesis of uranyl ion complexes displaying a wide range of architectures. Under the conditions used, the pure trans isomer gives only the complexes [UO₂(t-1,4-chdc)(H₂O)₂] (1) and [UO₂(t-1,4-chdc)] (2), which crystallize as one- and two-dimensional (1D and 2D) species, respectively. Complexes containing either the cis isomer alone or mixtures of the two isomers in varying proportion were obtained from the isomer mixture. The neutral complexes [UO₂(c-1,4-chdc)(DMF)] (3) and [UO₂(c-1,4-chdc)(bipy)] (4) are 2D and 1D assemblies, respectively, while all the other complexes are anionic and include various counterions. [C(NH₂)₃]₃[H₂NMe₂][(UO₂)₄(c-1,4-chdc)₆]·H₂O (5) crystallizes as a three-dimensional (3D) framework with {10³} topology. While [H₂NMe₂]₂[(UO₂)₂(c-1,4-chdc)₂(t-1,4-chdc)]·DMF·2H₂O (6) is a 1D ladderlike polymer, [H₂NMe₂]₂[(UO₂)₂(c-1,4-chdc)(t-1,4-chdc)₂]·2H₂O (7), which differs in the cis/trans ratio, is a 3-fold 2D interpenetrated network with {6³} honeycomb topology. The related [H₂NMe₂]₂[(UO₂)₂(c,t-1,4-chdc)₃]·2.5H₂O (8), with one disordered ligand of uncertain geometry, is a 3-fold 3D interpenetrated system. The two isomorphous complexes [Co(bipy)₃][(UO₂)₂(c-1,4-chdc)₃]·1.5H₂O (9) and [Cd(bipy)₃][(UO₂)₂(c-1,4-chdc)₃]·1.5H₂O (10) form 3D frameworks with the {10³} srs topological type. In contrast, [Ni(bipy)₃]₂[(UO₂)₄(c-1,4-chdc)₂(t-1,4-chdc)(NO₃)₆]·2H₂O (11) is a molecular, tetranuclear complex due to the presence of terminal nitrate ligands. A 2-fold 3D interpenetration of frameworks with {10³} ths topology is observed in [Cu(bipy)₂]₂[(UO₂)₂(c-1,4-chdc)₂(t-1,4-chdc)]·2H₂O (12), while [Zn(bipy)₃][(UO₂)₂(c-1,4-chdc)₃]·4H₂O (13) crystallizes as a 2D net with the common {4.8²} fes topological type. The additional Pb^II cation is an essential part of the 3D framework formed in [UO₂Pb₂(c-1,4-chdc)(t-1,4-chdc)₂(bipy)₂] (14), in which uranyl and its ligands alone form 1D subunits. Together with previous results, the solid-state uranyl emission properties of seven of the present complexes evidence a general trend, with the maxima for the complexes with O₆ equatorial environments being blue-shifted with respect to those for complexes with O₅ environments.

A series of Cd(ii) coordination polymers based on flexible bis(triazole) and multicarboxylate ligands: topological diversity, entanglement and properties

Eight Cd(ii) coordination polymers with diverse topologies based on 1,4-bis(1,2,4-triazol-4-ylmethyl)benzene and multicarboxylate ligands were synthesized and characterized. The 3D topologies of 1, 2 and 3 are unprecedented.

Polycatenation tuned microporosity of two metal–tris(4′-carboxybiphenyl)amine frameworks with multilayer structures

By employing a nanosized tris(4′-carboxybiphenyl)amine ligand to assemble with Zn²⁺ ions, a novel trilayer network (FIR-37) and an unprecedented 2D → 3D microporous polycatenation framework (FIR-38) based on unusual tetralayers have been synthesized and structurally characterized.