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The efficient backbone-directed self-assembly of cyclic metalla[3]catenanes by the combination of tetrachloroperylenediimide (TCPDI)-based dinuclear rhodium(III) clips and 4,4'-diazopyridine or 4,4'-dipyridylethylene ligands is realized in a single-step strategy. The topology and coordination geometry of the cyclic metalla[3]catenanes are characterized by NMR spectroscopy, ESI-TOF-MS spectrometry, UV/Vis-NIR spectroscopy, and X-ray diffraction studies. The most remarkable feature of the formed cyclic metalla[3]catenane is that it contains π-aggregates (ca. 2.6 nm) incorporating six TCPDIs. Further studies revealed that cyclic metalla[3]catenanes can be converted reversibly to their corresponding sodium adducts and precursor building blocks, respectively. This strategy opens the possibility of generating unique supramolecular structures from discrete functional π-aggregates with precise arrangements.

Metallosupramolecular poly-NHC-metal assemblies were prepared from trigonal hexakis (H6 -1 a(PF6 )6 and H6 -1 b(PF6 )6 ) or nonakis (H9 -3(BF4 )9 ) imidazolium salts and Ag2 O. Complexes [Ag6 (1 a)2 ](PF6 )6 and [Ag6 (1 b)2 ](PF6 )6 are built from six Ag+ ions sandwiched between two trigonal hexacarbene ligands with an inner and an outer NHC donor in each of the three ligand arms. The metal atoms are arranged in two triangles. The hexakis-NHC ligands bear cinnamic ester groups at the outlying NHC donors, used in postsynthetic [2+2] cycloaddition reactions linking two hexakis-NHC ligands by three cyclobutane units to give complexes [Ag6 (2 a)](PF6 )6 and [Ag6 (2 b)](PF6 )6 bearing a dodecacarbene ligand. From the related nonakisimidazolium salt H9 -3(BF4 )9 , complex [Ag9 (4)](BF4 )9 bearing an octadecacarbene ligand was obtained. Removal of the template metals yielded very large, stable, polyimidazolium cations with 12 or 18 internal imidazolium groups.

The incorporation of functional groups into the cavity of discrete supramolecular coordination cages (SCCs) will bring unique functions and applications. Here, three dicarboxylate ligands (H2 L1Cl, H2 L2Cl and H2 L3Cl) containing N-heterocyclic carbene (NHC) precursors as linkers were introduced to construct SCCs by combining with two C3 -symmertic (CpZr)3 (μ3 -O)(μ2 -OH)3 clusters as three-connect vertices, resulted in a series of rugby-like V2 E3 (V=vertex, E=edge) type homoleptic cages (SCC-1, SCC-2 and SCC-3). However, V4 E6 -type tetrahedral cages (SCC-4 and SCC-5), incorporating six Au-NHC moieties, were obtained when the corresponding NHC-gold(I) functionalized ligands (H2 L1Au , H2 L2Au ) were applied. For the first time, we present a trackable CpZr-involved cage to cage conversion to generate a heteroleptic V2 E3 cage (SCC-6) from two homoleptic cages (SCC-2 and SCC-5) with different geometries of V2 E3 and V4 E6 . The heteroleptic assembly SCC-6 can also be formed upon a subcomponent displacement strategy. The structural transformation and reassembly processes were detected and monitored by 1 H NMR spectroscopy and electrospray-ionization mass spectrometry. The formation of heteroleptic assembly was further supported by single crystal X-ray diffraction analysis. Moreover, homoleptic cage SCC-2 possesses a trigonal bipyramidal cationic cavity allowing the encapsulation of a series of sulfonate anionic guests.

Polyimidazolium-based cages are considered promising materials based on their fascinating properties and potential applications. These three-dimensional functional structures are highly desirable for the recognition of particular guest molecules, however, their synthesis remains challenging. In this work, we have designed and synthesizes a pure [n]-imidazolium (n=16) cage, the hexadecakisimidazolium salt H16 -2(PF6 )16 , from tetragonal octakisimidazolium salt H8 -1(PF6 )8 . The synthetic method involves formation of metal-carbene templates, a quadruple photochemical [2+2] cycloaddition reaction and subsequent removal of metal ions. Specifically, the synthesized cage, featuring sixteen imidazolium moieties, demonstrated high efficiency for the selective fluorescent recognition of 8-hydroxy-1,3,6-pyrene trisulfonate (HPTS). The present work not only further develops the metal-carbene template strategy by exploiting a new type of polyimidazolium cage, but also provides encouraging prospects for the design of versatile imidazolium-based functional acceptors.

The properties of supramolecular structures are highly dependent on their metal-centered building blocks and organic linkers, thus the search for novel systems will lead to new functions and applications for these unique assemblies. Here, two discrete triangular trimetallic sandwich building blocks were developed to construct supramolecular assemblies through coordination-driven self-assembly with organosulfur ligands. A series of tubelike (Tr2Pd3)4L6 assemblies (Tr = cycloheptatrienyl ring) were obtained from a discrete triangular tripalladium sandwich complex with bifunctional organosulfur ligands. By replacing the metal centers of the platinum analogue, the self-assembly process resulted in the clean formation of (Tr2Pt3)2L3 triple helicates instead of tubelike species. The trimetallic sandwich building blocks were also shown to form face-capped (Tr2M3)4L4 (M = Pd or Pt) tetrahedral cages when trifunctional organosulfur ligands were used. The supramolecular assemblies were comprehensively analyzed by X-ray crystallography. A metal-cluster-induced structural transformation between (Tr2Pd3)4L4 tubes and (Tr2Pt3)2L3 triple helicates was observed. Furthermore, the face-capped (Tr2Pd3)4L4 cage possesses a tetrahedral cavity allowing the encapsulation of a series of guests.

By systematic change of the solvothermal synthesis, three new coordination polymers, [Cd(L)∙(H2O)]∙2H2O (1), [Cd(L)∙(H2O)]∙H2O (2), and [Cd(L)] (3), have been synthesized based on a tritopic ligand 4-(pyridin-3-yl)isophthalic acid (H2L). Compounds 1 and 2 show very similar two-dimensional (2D) bilayers further linked by interlayer hydrogen bonds into three-dimensional (3D) supramolecular structures, while 3 displays a 3D structure constructed form one-dimensional (1D) Cd-carboxyl chains. Notably, 1 and 2 have a pair of unusual isomers with the opposite orientation of coordinated H2O on the metal centers, leading to different hydrogen bonding interactions. Thermal stabilities and solid-state photoluminescences for 1–3 were also investigated.

Because the adsorption/separation process plays a great role in chemical, petrochemical, pharmaceutical, environmental protection and many other fields, it has received extensive concern in both scientific research and practical applications. However, due to the new requirements and specific applications, it is a great necessity and urgency to explore new-type porous materials or maximize the adsorption capacity and improve the separation efficiency through endowing the adsorbent functionality to enable its special interactions with the adsorbates. The crystalline metal–organic framework (MOF) materials have shown great potentials in gas/liquid phase capture and separation due to their enormous porosities, tunable void properties, and easier modification, etc. Although there are lots of excellent reviews about functional MOFs in different fields, this review introduces the influence of MOF pore properties on the capture and separation of tailored guest molecules from the control of the supramolecular interactions for the first time. Some specific strategies are thus presented to enhance the adsorption/separation performance, and the relationships of the supramolecular interactions are well discussed between the adsorbates and adsorbents. Finally, the applications of porous MOF materials in adsorption/separation are further prospected and provided by the recent relevant studies.

In nature, proteins have evolved sophisticated cavities tailored for capturing target guests selectively among competitors of similar size, shape, and charge. The fundamental principles guiding the molecular recognition, such as self-assembly and complementarity, have inspired the development of biomimetic receptors. In the current work, we report a self-assembled triple anion helicate (host 2) featuring a cavity resembling that of the choline-binding protein ChoX, as revealed by crystal and density functional theory (DFT)-optimized structures, which binds choline in a unique dual-site-binding mode. This similarity in structure leads to a similarly high selectivity of host 2 for choline over its derivatives, as demonstrated by the NMR and fluorescence competition experiments. Furthermore, host 2 is able to act as a fluorescence displacement sensor for discriminating choline, acetylcholine, l-carnitine, and glycine betaine effectively., The choline-binding protein ChoX exhibits a synergistic dual-site binding mode that allows it to discriminate choline over structural analogues. Here, the authors design a biomimetic triple anion helicate receptor whose selectivity for choline arises from a similar binding mechanism.

Shape memory polymers (SMPs), with the capability to change from one or more temporary shapes to predetermined shapes in response to an external stimulus, have attracted much interest from both academia and industries. When introducing supramolecular interactions that have been featured as dynamic and reversible into the design of novel SMPs, intriguing and unique functionalities have been engendered and thereby broaden the potential applications of the SMPs to new territories. In this review, we summarize recent progress made in SMPs based on supramolecular interactions, provide insight into the material design and shape memory mechanism, elucidate and evaluate their properties and performance, and point out opportunities and applications of SMPs.

In contrast to the stable dinitrogen molecule, white phosphorus (P4) and yellow arsenic (As4) are very reactive allotropic modifications of these two heavier pnictogen elements, which has greatly hampered the study of their properties and applications. Thus, the safe storage and transport of them is imperative. Supramolecular caged structures are one of the most efficient approaches for the encapsulation and stabilization of reactive species; however, their use in the P4 and As4 chemistry is very rare. In the current work, we demonstrate a new design strategy for constructing finite cages and including guests based on anion coordination chemistry. The phosphate-coordination-based tetrahedral cages can readily accommodate the tetrahedral guests P4 and As4, which is facilitated by the shape and size complementarity as well as favorable σ–π and lone-pair−π interactions. Moreover, the latter case represents the first example of As4 inclusion in a well-defined tetrahedral cage.

A new metal–organic framework, [Zn3(μ3-OH)(tzba)2(bpy)(H2O)]OH·DMF (1), was solvothermally synthesized by employing tetrazolate-carboxylate 4-(1H-tetrazol-5-yl) benzoic acid (H2tzba) linker and 2,2′-bipyridine (bpy) chelating coligand. 1 contains novel Zn6(μ3-OH)2(μ2-H2O)2(COO)4(N4C)2 hexanuclear clusters and reveals a three-dimensional (3D) microporous supramolecular framework based on the stacked 2D layers. The highly polar pores cause not only strong affinity towards CO2 molecules but also a significant selective adsorption of CO2 over CH4. Meanwhile, the multiple binding sites for CO2 in the framework were determined by Grand Canonical Monte Carlo (GCMC) simulations. 1 also shows strong blue luminescence from ligand-to-metal charge transfer (LMCT).

A series of supramolecular assemblies of types [Ag8 (L)4 ](PF6 )8 and [Ag4 (L)2 ](PF6 )4 , obtained from the tetraphenylethylene (TPE) bridged tetrakis(1,2,4-triazolium) salts H4 -L(PF6 )4 and AgI ions, is described. The assembly type obtained dependends on the N-wingtip substituents of H4 -L(PF6 )4 . Changes in the lengths of the N4-wingtip substituents enables controlled formation of assemblies with either [Ag4 (L)2 ](PF6 )4 or [Ag8 (L)4 ](PF6 )8 stoichiometry. The molecular structures of selected [Ag8 (L)4 ](PF6 )8 and [Ag4 (L)2 ](PF6 )4 assemblies were determined by X-ray diffraction analyses. While H4 -L(PF6 )4 does not exhibit fluorescence in solution, their tetra-NHC (NHC=N-heterocyclic carbene) assemblies do upon NHC-metal coordination. Upon irradiation, all assemblies undergo a light-induced, supramolecule-to-supramolecule structural transformation by an oxidative photocyclization involving phenyl groups of the TPE core, resulting in a significant change of the luminescence properties.

Low molecular weight heparin (LMWH) is a natural sulfated glycosaminoglycan with the affinity to proangiogenic factors, rendering it a promising agent for tumor therapy. Inspired by DOX binding to the helix of DNA, mitochondrial damage KLA peptide derivative (mKLA) and anti-angiogenic LMWH-chrysin conjugate (LC) are constructed to simulate the double strands for doxorubicin (DOX) binding (LKD nanocomplex). Initiated and “locked” by DOX, mKLA and LC temporarily aggregate by π-π stacks, electrostatic and hydrophobic interactions in aqueous condition with self-amplified DOX loading (19.07 ± 1.08 wt%). During endosome-lysosome trafficking, DOX protonated by H+ could “unlock” the LKD nanocomplex to disassemble, which enables mKLA and DOX to damage mitochondria and nucleus DNA respectively, and LMWH could also inhibit angiogenesis. Based on the strong inhibition of tumors at all stages in vivo, we hold that LKD nanocomplex provides a new opportunity based on smart construction of carbohydrate materials for clinically advanced cancer patients.

A new class of supramolecular metallacycles capable of undergoing photochemical reactions and in situ release of cyclobutanes in solution is described. The molecular metallacycles were generated through coordination-driven self-assembly of dinuclear metal-carbene complexes as organometallic clips with olefin-functionalized bridging ligands. Photolysis of these molecular metallacycles in situ led to structural interconversion and release of the formed cyclobutane products with quantitative conversion. Further modifications of the obtained cyclobutanes provided a series of new species containing the cyclobutane skeleton.

A new zinc(II) coordination polymer, namely [Zn(bipy)2(H2O)4]n·n(dsba) (1), has been synthesized by the mixed 4,4′-biphenyldisulfonic acid (H2dsba) and 4,4′-bipyridine (bipy) ligands with Zinc(II) salt under the common solution evaporation method. The results of the X-ray crystal diffraction analysis show that complex 1 belongs to the monoclinic system with P21/c space group. The unit cell constants of complex 1 are a = 9.2579 A, b = 12.2016 A, c = 14.447 A, α = γ = 90˚, β = 93.476˚. Complex 1 exhibits a three-dimensional supramolecular network based on the discrete structure by utilizing various H-bonded interactions. In addition, the properties of complex 1, such as the elemental analysis, FT-IR spectroscopy, X-ray powder diffraction, and fluorescence spectroscopy were also characterized and are discussed in detailed.

Homoleptic and heteroleptic cylinder-shaped poly-NHC metallosupramolecular assemblies [Ag3 (L)2 ](BF4 )3 have been prepared by control of the shape, size, and electronic properties of disk-shaped trisimidazolium salts of type H3 -L(BF4 )3 . Both imidazolium salts with an electron-deficient triazine backbone H3 -A(BF4 )3 or an electron-rich benzene backbone H3 -D(BF4 )3 have been employed. Reaction of H3 -A(BF4 )3 or H3 -D(BF4 )3 with Ag2 O yield trinuclear homoligand complexes [Ag3 (L)2 ](BF4 )3 (L=A, D). However, equimolar mixtures of H3 -A(BF4 )3 and H3 -D(BF4 )3 react with Ag2 O under social self-sorting to give the heteroligand assembly [Ag3 (A)(D)](BF4 )3 . The same heteroligand assembly was obtained by transmetallation from mixtures of complexes [Ag3 (A)2 ](BF4 )3 and [Ag3 (D)2 ](BF4 )3 . The transmetallation from [Ag3 (A)(D)](BF4 )3 to [Au3 (A)(D)](BF4 )3 is also demonstrated. The study expands to concepts of narcissistic and social self-sorting from classical Werner-type ligands to organometallic NHC chemistry thereby opening new routes for the construction of poly-NHC metal assemblies with increasing complexity.

Although the coordination chemistry of N-heterocyclic carbenes (NHCs) with transition metals has been explored for half a century, only in the past ten years has the chemistry of metallosupramolecular assemblies based on poly-NHC ligands been studied more extensively. Remarkable discrete assemblies featuring poly-NHC ligands including two-dimensional metallacycles and three-dimensional metallaprisms/cages have since emerged. These assemblies are mostly obtained starting from various imidazolium or benzimidazolium salts. Driven by the increasing interest in new supramolecular architectures from carbon donor ligands, design, and construction of poly-NHC metal assemblies has become a rapidly growing area of research. The metal-carbene bond length is fixed to approximately 2.0 Å in linear NHC-M-NHC complexes. This allows the use of such complexes bearing olefin-substituted NHC ligands as templates for subsequent photochemical [2 + 2] cycloaddition reactions. The postassembly modification of such assemblies has been actively explored in recent years. In this review, we focus on the synthetic methods, characterization, structural features, and postassembly modifications of metallosupramolecular assemblies obtained from poly-NHC ligands.

Caged supramolecular systems are promising hosts for guest inclusion, separation, and stabilization. Well-studied examples are mainly metal-coordination-based or covalent architectures. An anion-coordination-based cage that is capable of encapsulating halocarbon guests is reported for the first time. This A4L4-type (A=anion) tetrahedral cage, [(PO4)4L4](12-), assembled from a C3-symmetric tris(bisurea) ligand (L) and phosphate ion (PO4(3-)), readily accommodates a series of quasi-tetrahedral halocarbons, such as the Freon components CFCl3, CF2Cl2, CHFCl2, and C(CH3)F3, and chlorocarbons CH2Cl2, CHCl3, CCl4, C(CH3)Cl3, C(CH3)2Cl2, and C(CH3)3Cl. The guest encapsulation in the solid state is confirmed by crystal structures, while the host-guest interactions in solution were demonstrated by NMR techniques.

Seven new mixed–ligand coordination polymers, {[Co0.5(bib)0.5(tftpa)0.5]·0.5H2O}n (1), [Cd2(bib)(tftpa)2]n (2), [Ni0.5(bib)0.5(tftpa)0.5]n (3), {[Co0.5(tftpa)(H2O)]·0.5bib·EtOH}n (4), {[Cd0.5(tftpa)(H2O)]·0.5bib·EtOH}n (5), [Cd3(bib)3(tftpa)3(MeOH)3]n (6), and [Cd(bib)(tftpa)(MeOH)]n (7) (bib = 1,4-bis(2-methylimidazol-1-yl)butane, H2tftpa = tetrafluoroterephthalic acid) have been synthesized under different reaction conditions and characterized by elemental analysis, IR, PXRD, single crystal X-ray diffraction analysis and thermogravimetric analysis. Complex 1 exhibits an unusual [2 + 2] interpenetrating diamond framework belonging to class IIIa with the point symbol 66. Complex 2 reveals a (3,4)-connected 3D framework with a unique double-stranded helical chain based on Cd–O–Cd and Cd–(COO)–Cd. Complex 3 presents a 4-fold interpenetrating 3D diamond framework belonging to class Ia with the point symbol 66. Complexes 4 and 5 display a 3D supramolecular architecture built on 2D stacked layers through hydrogen bonding and π–π interactions. Complex 6 also shows a 3D 4-fold interpenetrating diamond framework belonging to class Ia with the point symbol 66. Complex 7 features a 2D + 2D → 2D parallel polycatenated framework with the point symbol 44·62. The structural diversity of complexes 1–7 illustrate that a subtle change can have a marked effect on the crystal architectures. Moreover, the magnetic properties of complexes 1, 3, and 4, and the solid-state photoluminescence results for complexes 2, and 5–7 were also studied.

Five new solvent-induced cadmium coordination architectures, {[Cd(bib)(5-Br-H2ip)]·EtOH}n (1), {[Cd0.5(bib)0.5(5-Br-H2ip)0.5]·3H2O}n (2), {[Cd2(bib)(5-Br-H2ip)2(MeOH)]}n (3), {[Cd(bib)0.5(5-Br-H2ip)(H2O)2]·H2O}n (4), and {[Cd(bib)0.5(5-Br-H2ip)(H2O)]}n (5), have been constructed from the same materials (1,4-bis(2-methyl-imidazol-1-yl)butane (bib), 5-bromoisophthalic acid (5-Br-H2ip) and Cd(Ac)2·2H2O) under different reaction solvents. As controlled by solvent systems, compound 1 shows a 3-fold interpenetrating 3D framework based on the left- and right-handed helical chains, while compound 2 reveals a 3-fold interpenetrating 3D network and each single net is based on the left-handed, right-handed and meso-helical chains. Compound 3 is a 3D framework that can be simplified as a 6-connected net with (48·62) topology. Both 4 and 5 display 3D supramolecular frameworks through weak aromatic π–π stacking interactions and hydrogen bonding interactions. However, the topologies of 4 and 5 are definitely different. Compound 4 presents a 3-connected net with (82·10) topology, while compound 5 reveals a 4-connected net with (42·63·8) topology. The effects of solvents on the crystal structures were discussed and thermogravimetric analysis and solid-state photoluminescence results for 1–5 were investigated.

Two new copper coordination complexes, [Cu(PI)(OX)(H2O)]·H2O (1) and [Cu(PI)(fum)(H2O)]·H2O (2) [PI = 2-(2′-pyridyl) imidazoline, OX2− = dianion of oxalic acid and fum2− = dianion of fumaric acid], were synthesized by interface diffusion method based on Cu(II) ions, PI ligands and aliphatic dicarboxylic acids. Complex 1 is a mononuclear complex which spreads into a 3D (4,9)-connected supramolecular network via hydrogen bond interactions, while complex 2 features a 1D zigzag chain with two different orientations. These two compounds are characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, infrared spectra, and thermogravimetric analyses.

A new one-dimensional (1D) 4d–4f heterometallic coordination polymer [ErAg(Himdc)2(H2O)3] (1) (H3imdc = 4,5-imidazoledicarboxylic acid) is synthesized under hydrothermal condition and characterized by elemental analysis, IR, PXRD and single crystal X-ray diffraction. Complex 1 crystallizes in the triclinic space group P-1, showing a 1D metal–organic pseudo-nanotube with a 4.014 × 12.027 A2 cross-section. Furthermore, it assembles into a 3D supramolecular architecture via hydrogen bonds between pseudo-nanotubes. The complex 1 exhibits solid-state photoluminescence and high thermal stability.

A new 1D Pb(II) coordination polymer, {[Pb(Hbidc)(phen)]·H2O}n (1), has been synthesized by a solvothermal method based on 1H-benzimidazole-5,6-dicarboxylato (H3bidc) and 1,10-phenanthroline (phen). Complex 1 features two types of helical chains, a 1D left- and right-handed double-stranded helical chain and a supramolecular helical chain, which interweave into a new (3,3,6)-connected achiral 3D supramolecular network. Notably, the supramolecular helical chains are induced by the different spatial orientations of the 1D double-stranded helical chains. The structure and properties of 1 have been determined by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), elemental analysis (EA), thermogravimetric (TG) analysis and solid state fluorescence spectra.

Three new coordination complexes, namely [Cd(HL)(μ-bpp)(H2O)]n·(H2O)n (1), [Co(HL)(μ-bpp)]n·(H2O)n (2), and [Ag2(L)2/3(μ-bpp)]n (3) [H3L = 3-(4-carboxyphenoxy)phthalic acid and bpp = 1,3-bis(4-pyridyl)propane], have been successfully synthesized by using H3L and accessory bridging ligand. The predominant influence in 1–3 may be the nature of different metal ions, which result in the complexes assembling into supramolecular frameworks with different topological nets. Structural analysis reveals that the structure of 1 can be described as a 2D network with Point (Schalfli) symbol for net: {66} topology. Complex 2 shows the similar 2D 44 grid-like layers by the intermolecular hydrogen bonds, whereas dinuclear Ag(I) clusters in 3 act as coordination nodes, forming a sandwich-like 2D structure. In addition, the magnetic behavior of 2 was also studied.

Theseanalogies provide promising ideas for the self-assembly ofnovel supramolecular systems based on anion coordination.In the past few decades, zero-dimensional, aestheticallypleasing metal coordination complexes, such as molecularsquares, capsules, tetrahedra, and other complex polyhedralshapes, have attracted much interest.

Four Ag(I)/Co(II) complexes based on a flexible V-shaped ligand 3,3′, 4,4′-diphenylsulfone tetracarboxylic acid (H4dstc), namely [Ag(bpe)2]·H3dstc (1), {[Ag2(H2dstc)(bpp)(H2O)]·H2O}n (2), {[Co2(dstc)(bpe)2(H2O)2]·2H2O}n (3) and {[Co4(dstc)2(bpa)3(H2O)6]·7H2O}n (4) have been synthesized in the presence of different rod-like N-donor ligands 1,2-di(4-pyridyl)ethylene (bpe), 1,3-bis(4-pyridyl)propane (bpp), and 1,2-bis(4-pyridyl)ethane (bpa). In complex 1, the H3dstc– ligand does not take part in coordination but balances the charge by its one deprotonated carboxylate group. Complex 2 contains two different motifs: a cationic 1D chain [Ag(bpp)]+ and an anionic 1D meso-helix [Ag(H2dstc)(H2O)]–. Interestingly, the non-covalent hydrogen bonding interactions extend such simple discrete units or 1D chains into 3D supramolecular architectures. Complex 3 represents a 3D binodal 4-connected (64·82) network, while complex 4 can be simplified as a primitive cubic (pcu) network. In addition, the photoluminescence of 1 and 2 and the magnetism of 3 and 4 are investigated, respectively.

Three new 2D complexes were constructed by reaction of Co(NO3)2·6H2O with 4,4′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda) in three different solvents (N,N′-dimethylformamide (DMF), N,N′-dimethylacetamide (DMA), and N-methylpyrrolidinone (DMP)), formulated as {[Co1.5(cpbda)(DMF)(H2O)3]·(DMF)}n (1), {[Co1.5(cpbda)(DMA)(H2O)3]·(DMA)}n (2), and {[Co1.5(cpbda)(DMP)(H2O)3]·(DMP)}n (3). Complexes were characterized by X-ray single-crystal diffraction, elemental analysis (EA), powder x-ray diffraction (PXRD), infrared spectra (IR), and thermogravimetric analysis (TGA). The solvents (DMF, DMA, and DMP) were incorporated in the final supramolecular structures, respectively, giving rise to three similar 2D frameworks. However, the special active replaceable coordination sites in the 1D channel were also discovered. The synthesis procedure was sensitive to small molecular carbonyl solvents (DMF, DMA, and DMP), but the hydroxy (methanol and alcohol) was not identified. The different coordinated and la...

We show here the supramolecular isomerism, with respect to shape-asymmetry of ligand and the new hierarchical classification for supramolecular isomerism, the three-level isomerism, which was advanced based on a thorough investigation for the four new Ni/dpt24 polymorphs [Hdpt24 = 3-(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole)]. Compounds 1, 2, and 3 are three-dimensional twofold interpenetrated porous coordination polymers with NbO topology, while 4 with two-dimensional grid structure is termed as the primary isomer of 1/2/3 due to the difference of dimensionality. Complex 3 possessing different shape-asymmetry of single networks from 1 and 2, is called as the secondary isomer of 1 and 2. Complexes 1 and 2 possess the same topology, single shape-asymmetry networks, but different interpenetration-orientation and interpenetration-asymmetry, and are defined as the tertiary isomers. Distinct differences in H2 and CO2 adsorption capacity were observed among each level of isomers. In addition, the hierarchical classification's relationship with characteristic classifications has been discussed.

A coordination polymer, [Pb2(OH)(tzia)]·2H2O (1), has been prepared by solvothermal reaction of 5-(1H-tetrazol-5-yl)isophthalic acid (H3tzia) and Pb(NO3)2. The polymer 1 is based on an unprecedented centrosymmetric tetranuclear [Pb4(OH)2(COO)4(ttaz)2] cluster linked by a multidentate tzia ligand, affording a 2-D 3,6-connected kgd layer. The adjacent layers are further jointed by Pb⋯O interactions to form a 3-D supramolecular framework with a rare (3,8)-connected tfz-d; UO3 topology. Photoluminescent properties of H3tzia, 1, and 1-desolvated have been further investigated, and it was interesting to find that 1-desolvated due to the removal of lattice water molecules reveals stronger photoluminescence than 1.

A V-shaped ligand bis(N-methylbenzimidazol-2-ylmethyl)benzylamine (L) and its zinc(II) complex, [ZnL 2](pic)2 · 2CH3CN (pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray crystallographic analysis revealed that the Zn(II) complex possesses a distorted trigonal bipyramidal geometry. Supramolecular interactions arising from various intra- or intermolecular π···π stacking interactions contributed to the form of the multidimensional configuration. Interactions of L and Zn(II) complex with DNA were monitored using spectrophotometric methods and viscosity measurements. The results suggest that L and Zn(II) complex both bind to DNA via intercalation and Zn(II) complex binds to DNA more strongly than L. Moreover, the Zn(II) complex also exhibited potential antioxidant properties in vitro.

A new coordination compound [Ag(Hcpob)(bpy)] n ( 1 ) was assembled by 4-(3′-carboxylphenoxy)benzoic acid (H 2 cpob), 4,4′-bipyridine (bpy) and AgNO 3 under the hydrothermal synthesis. Especially, H 2 cpob came from the in situ decarboxylation of 4-(2′,3′-dicarboxylphenoxy)benzoic acid (H 3 dpob) in the hydrothermal reaction. Single-crystal X-ray diffraction reveals that 1 crystallizes in a monoclinic P 2 1 /c space group. 1 displays a one-dimensional (1D) fishbone-like double chain structure constructed from Ag(I) ions, bpy ligands and partly deprotonated H 2 dpob ligands, which further form a three-dimensional (3D) supramolecular architecture via π–π stacking and hydrogen-bonding interactions. In addition, the photoluminescence of 1 has been investigated in detail.

Two new coordination polymers, [Pb(bpdc)] n (1) and [Co(bpdc)(phen)] n (2) [H2bpdc = benzophenone-2,4′-dicarboxylic acid, phen = 1,10-phenanthroline], have been synthesized and structurally characterized. Hydrogen bonding and π ··· π stacking extend 1 and 2 into 3-D supramolecular architectures, where 1 exhibits a 3-D framework with 1-D hairpin-like helicates based on Pb–O covalent bonds and 2 displays a 3-D network with 1-D zipper-like chains based on Co–O and Co–N covalent bonds. The FT-IR spectra, PXRD and TG analyses are discussed for 1 and 2. Fluorescence spectra and luminescent lifetime are studied for 1.

A new two-dimensional Cu(I)-framework [Cu3(deppz)(mtta)I] (1) [(Hdeppz = 3,5-diethyl-4-(4-pyridyl)-pyrazole, Hmtta = 5-methyltetrazole] has been solvothermally synthesized and structurally characterized. The framework contains an unprecedented cyclic Cu4(μ-pz)2(μ-mtta)2 cluster (Cu4) with twelve-membered coplanar Cu4N8 metallocycle, which contains coordinatively unsaturated Cu(I) centers and acts as a soft π-acid motif to contact with iodine atoms from Cu2I2 dimer of adjacent layers, generating a 3D supramolecular framework. The framework exhibits high thermostability and bright green-blue solid-state luminescence.

Three Zn II /Cd II -coordination polymers based on 2-propyl-4,5-imidazoledicarboxylate (H 3 pimdc), namely, [Zn(Hpimdc)H 2 O] n ( 1 ), [Cd(H 2 pimdc) 2 ] n ( 2 ) and [Cd 2 (Hpimdc) 2 (bbi) 0.5 (H 2 O) 2 ] n [bbi = 1,10-(1,4-butanediyl)bis(imidazole)] ( 3 ), have hydrothermally been synthesized, which exhibit a systematic dimensional variation by changing the metal ions or introducing the auxiliary ligand. Complex 1 is a 1D zig-zag polymeric chain, which is finally extended into a 3D supramolecular network through R 4 4 (12) O–H⋯O H-bonding rings. Complex 2 shows a 2D layer comprised alternately arranged left- and right-handed helical chains. Complex 3 features a rare (3,3)-connected 8 3 network with opposite chiral layers in a slipped ABAB fashion. The photoluminescent properties and thermal stabilities of three complexes are also discussed.

Three new fluorous coordination polymers with a fluorinated carboxylate tecton and N-donor co-ligands, {[Zn2(hfipbb)2(phen)2]·2H2O}n (1), [Zn2(hfipbb)2(bipy)(H2O)]n (2), and [Zn5(hfipbb)4 (Hhfipbb)2 (bpp)]n (3), [H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), phen = 1,10-phenthroline, bipy = 4,4′-bipyridine, and bpp = 1,3-bi(4-pyridyl)propane], have been prepared and characterized by elemental analysis, IR spectra, and X-ray diffraction. Compound 1 exhibits a 3D supramolecular network assembled from two independent 1D chain motifs [Zn(hfipbb)(phen)] through π⋯π stacking, and C–H⋯F and O–H⋯O interactions. Compound 2 features 2D undulating layer structure with 44-sql network. Whereas, in compound 3, pentanuclear [Zn5(η2-O)2(μ2-η1:η1-CO2)]2− cores are bridged by hfipbb2− and bpp ligands into a 3D 6-connected sxd framework with a point symbol of (33·46·55·6). The diverse arrangements of the compounds show the modulation of the heterocyclic N-donor co-ligands can suitably mediate the coordination requirement of metal centers as well as the binding modes of fluorinated carboxylate tecton, which consequently generate diverse crystalline architectures. In addition, the properties of thermogravimetric analysis, X-ray powder diffraction, and photoluminescent behaviors of the compounds have also been discussed.

Five novel Zn(II)/Cd(II)-based coordination polymers 1–5 with a flexible disulfide derivative of the nicotinate 6,6′-dithiodinicotinic acid (H2cpds) and two rodlike N,N′-donor ligands (bpa =1,2-bi(4-pyridyl)ethane; bpp = 1,3-bis(4-pyridyl)propane) have been successfully synthesized under the liquid diffusion condition and characterized by elemental analysis, IR spectra, and X-ray diffraction, namely {[Zn(cpds)]·H2O}n (1), {[Zn(cpds)(bpa)0.5]}n (2), {[Zn(cpds)(bpp)]}n (3), {[Cd(cpds)(bpa)1.5]·H2O}n (4), and {[Cd2(cpds)2(bpp)·(H2O)3]·4H2O}n (5). Complexes 1–5 display various coordination motifs due to different conformations, and coordination modes of the H2cpds ligand, at the same time the effect of the auxiliary ligands plays important roles in the construction of extended supramolecular networks. Complexes 2–4 all exhibit 2D layer structures, in which 2 displays a 2-fold 2D → 2D parallel interpenetration framework containing a rotaxane-like motif and 3 is a 2D 44 gridlike layer. Compound 4 contains two k...

Three new coordination polymers, namely, {[Cd 3 (L 1 ) 2 (IP) 2 (H 2 O) 4 ]} n ( 1 ), {[Cd 2 (L 2 ) 2 (IP) 2 ]·(CH 3 OH)(DMF)} n ( 2 ) and [Cd(L 3 )(IP)] n ( 3 ) (H 3 L 1 = benzene-1,2,4-tricarboxylic acid, H 2 L 2 = 2,2-bis(4-carboxyphenyl)hexafluoropropane, H 2 L 3 = 1,3-phenylenediacetic acid and IP = 1H-imidazo[4,5-f][1,10]-phenanthroline), were prepared via self-assembly of pharmaceutical agent IP with cadmium sulfate in the presence of the different backbones of carboxylate linkers under mild conditions. All the polymers possess 2D structural motifs. The rigid tricarboxylate ligand links the metal centers to form a tetranuclear core in 1 . In 2 , the 2D network with trinuclear cores is further extended into 3D supramolecular arrays through aromatic stacking interactions. Interestingly, IP ligand acts in a tridentate mode via the two N atoms of pyridyl rings and the third N atom of imidazole ring and connects metal atoms into 1D zigzag chain in 3 . The structural analysis reveals that the backbones of carboxylates have critical effect on the construction of the complexes. Solid-state luminescent spectra of the Cd(II) complexes indicate intense fluorescent emissions.

The self-assembly of a V-shaped ligand 3,3′,4,4′-diphenylsulfonetetracarboxylate (dstc) and metal salts in the presence of a series of N-donor ligands yielded four new complexes, namely, [Cu 4 (H 2 dstc) 4 (phen) 4 ]·12H 2 O ( 1 ), {[Cu 2 (dstc)(bpe)(H 2 O) 2 ]·4H 2 O} n ( 2 ), [Cu 3 (dstc)(bipy)(μ 2 -OH) 2 (H 2 O) 2 ] n ( 3 ), {[Cd 5 (dstc) 2 (bipy) 2 (μ 3 -OH) 2 (H 2 O) 4 ]·4H 2 O} n ( 4 ) (phen = 1,10-phenanthroline; bpe = 1,2-bis(4-pyridyl)ethene; bipy = 4,4′-bipyridine). All the complexes were structurally determined by single-crystal X-ray diffraction and characterized by elemental analyses, IR spectra, X-ray powder diffraction and TG analyses. Complex 1 is a discrete tetranuclear unit, which further assembles into a 3D supramolecular framework by intermolecular hydrogen bonding interactions. Complex 2 is composed of 2D 4 4 grid-like layers based on dinuclear copper units. Complex 3 features a rare 3D (6,8)-connected topological net consisting of trimetallic clusters. 12-connected pentanuclear cadmium clusters are observed in complex 4 and the resulting structure shows an uncommon (4,12)-connected topology. The structural differences among 1 – 4 demonstrate that the nature of the N-donor assistant ligands and metal ions can play critical roles in the formation and structures of the resulting complexes. Magnetic studies showed antiferromagnetic interactions for 1 and 3 . In addition, the luminescent property of 4 was also studied.

The conformational bis-triazole ligand 4,4'-bis[(1,2,4-triazol-1-yl)methyl]biphenyl (btmb, 1), was successfully synthesized, and seven new coordination polymers, namely {M(oba)-(btmb)} n [M = Cd 2+ (2), Co 2+ (3), Ni 2+ (4), and Zn 2+ (5)], {M(sdba)(btmb)} n [M = Co 2+ (6) and Cd 2+ (7)], and {[Cu(H 2 odpa)(btmb)(H2O)]·2H20} n (8), (H 2 oba = 4,4'-oxydibenzoic acid, H 2 sdba = 4,4'-sulfonyldibenzoic acid, and H 4 odpa = 4,4'-oxydiphthalic acid), have been synthesized by utilizing the btmb ligand and the polymers have been characterized in detail. Complexes 2-4 are isostructural exhibiting 2D-layer structures and can be described as (3,4)-connected networks with (4 2 .6 3 .8)(4 2 .6) topological notation. Complex 5 shows 2D layers with left- and right-handed helical chains and has a (3,4)-connected net with (4.5 2 )(4.5 3 .7 2 ) topology. Complexes 6 and 7 are isostructural and display 2D undulating networks with (4,4) sheets that are further packed through van der Waals interactions to generate a 3D supramolecular structure. Complex 8 also represents a 2D network with a 4 4 -sql net, which is extended into a 3D supramolecular framework by hydrogen-bonding interactions. The structural differences of these complexes demonstrate that the conformation of the btmb ligand and flexible aromatic polycarboxylate anions play critical roles in the formation of the resulting frameworks. Furthermore, their thermal properties have been studied by thermogravimetric analysis (TGA) and the TGA results reveal that the triazole-based frameworks have a high thermal stability, which suggests they are good candidates for the construction of more stable complexes. The photoluminescent properties of complexes 2, 5, and 7 have also been studied.

The reaction of a ditopic diiminopyridine ligand 2,6-bis(1-(2,6-diisopropyl-4-(pyridin-3-yl)phenylimino)ethyl)pyridine (L) with group 12 metal salts in various solvent systems afforded 12 metal−organic coordination complexes, including zero-dimensional (0D) metallomacrocycle, one-dimensional (1D) chain, and two-dimensional (2D) network structures: [Zn4Cl8L2]·2C7H8·2CH3COCH3·3H2O (1a), {[Zn2Cl4L]·2CH3OH·2CHCl3·2H2O}n (1b), {[ZnCl2L]·0.5CH2Cl2·0.5H2O}n (1c), {[ZnBr2L]·CH2Cl2}n (2), [ZnI2L]n (3), {[Zn(NO3)2L2·2C7H8]}n (4), {[CdCl2L2]·2CH2Cl2}n (5), {[Cd(NO3)2L2]·CH2Cl2}n (6), {[Cd(ClO4)2L2]·CH2Cl2}n (7), {[Hg4(μ2-L2)(μ2-Cl2)(μ-HgCl2)Cl6]·2H2O}n (8), {[HgBr2L]·CH3CN·0.5CH2Cl2}n (9), and {[HgI2L]·0.5CH2Cl2}n (10). In these complexes, the semirigid ligand L exhibits four kinds of coordination modes [(syn, syn, syn), (syn, syn, anti), (anti, anti, syn), (anti, anti, anti)], leading to the formation of various supramolecular structures. Complex 1a is a tetranuclear metallomacrocycle. 1b contains 1D zigzag chains ...

An investigation into 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and cupric or cadmium complexes with a large variety of aliphatic α,ω-dicarboxylic acids HOOC-X-COOH (X = (CH2)n, n = 0–4 corresponding to oxalic acid (H2ox), malonic acid (H2mal), succinic acid (H2suc), glutaric acid (H2glu) and adipic acid (H2adi); CHCH, maleic acid (H2male) and fumaric acid (H2fum)) is performed. Ten novel metal–organic architectures, [Cu2(bpt)(ox)2]n·2.92nH2O (1), [Cu(bpt)(mal)(H2O)]n·2nH2O (2), [Cu(bpt)(glu)]n (3), [Cu(bpt)(adi)]n (4), [Cu2(bpt)2(fum)2]n·3nH2O (5), [Cd(bpt)(mal)(H2O)]n (6), [Cd(bpt)(suc)]n (7), [Cd(bpt)(glu)]n·nH2O (8), [Cd2(bpt)2(male)2]n·2nH2O (9), and [Cd(bpt)(fum)(H2O)]n·nH2O (10) were successfully synthesized through varying the organic acid linkers. The molecule 1 is a 3D pillared-layer framework with the open channels encapsulating infinite 1D water chains. Complex 2 shows the contorted 2D layer, which is extended to a 2-fold interpenetrated 3D supramolecular net by antidromic R24(8) hydrogen-bonding pattern. Compound 3 is a grid-like layer motif with the terminal bpt ligands as pendants. The MOFs 4 and 5 present two-fold interpenetrating primitive cubic (α-Po) coordination networks. Interestingly, discrete tetrameric water clusters exist in the micropores of the MOF 5. For the cadmium complex 6, six-coordinated metal centers link malonate and bpt to form interdigitated layers through edge-to-face π–π stacking interactions. Coordination polymer 7 can be considered as six-connected self-penetrated topological 3D network, in which the right- and left-handed helices are alternately arranged into a wavy Cd/succinate layer. Flexible glutarate with cadmium atoms produces a 1D ribbon, and is further linked by bpt ligands to produce the 2D double-layered motif 8. Incorporating with rigid butenedioic acid, the reaction of seven-coordinated cadmium and bpt leads to two distinct 2D (4,4) layered frameworks 9 and 10, with a one-dimensional Cd–O chain observed in the former framework. A systematic structural comparison of these ten complexes indicates that the final polymeric structures could be tuned through the introduction of the different backbone length and flexibility of the aliphatic dicarboxylates. In addition, host–guest chemistry of MOFs 1 and 5, and the luminescent properties of cadmium compounds were discussed.

Two new compounds, [Ag(Hppdb)]n (1) and {[Ag2(Hppdb)2(bpe)]·5.5H2O}n(2) [H2ppdb = [2,3-f]pyrazino[1,10]phenanthroline-2,3-dicarboxylic acid, bpe = trans-1,2-bis(4-pyridyl)ethylene], were synthesized and characterized. In 1, Hppdb– ions link AgI cations to form an infinite 1D [–Ag–(Hppdb)–Ag–]n chain, furthermore, the dimensionality is extended to 2D layers through synergistic π–π stacking, hydrogen-bonding and weak Ag···O interactions. Correspondingly, the dimeric [(Ag)(Hppdb)]2 subunits in 2 are connected by bpe ligands to generate a loop-link-shaped 1D chain motif, which is further joined through a R22(18)C–H···O hydrogen-bonding ring to afford interesting diagonal/diagonal inclined catenation 2D + 2D 3D supramolecular architectures. In addition, solid-state properties such as photoluminescence and thermal stability of the two compounds were studied.

Three new complexes based on V-shaped linkages 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and 4,4′-oxybis(benzoic acid) (H2oba), [Mn(bpt)(oba)(H2O)3]n·nH2O (1), [Co2(bpt)2(oba)(H2O)7]·(oba) (2), and [Cd2(oba)2(H2O)6]n·2n(bpt)·2nH2O (3) have been synthesized using different transition metal acetates. Non-covalent hydrogen bonding interactions extend complexes 1, 2 and 3 into supramolecular architectures. Complex 1 is a 3D framework, in which two types of helical H-bonded chains appear simultaneously. Complexes 2 and 3 contain 1D open channels encapsulating organic guest molecules – oba and bpt, respectively. Topologically, complex 3 is a α-Po structure. This work indicates that the building blocks oba and bpt can adopt versatile coordination modes depending on the nature of the metal centers. The elemental analysis, IR spectra, XRPD and TG analysis for three complexes, as well as luminescent properties for 3 are discussed.

Six new coordination polymers based on V-shaped linkage 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and transition metal ions, [Co(bpt)(pm) 0.5 (H 2 O)] n · 3 n H 2 O ( 1 ), [Cu 2 (bpt)(pm)(H 2 O) 4 ] n ( 2 ), [Co(bpt)(pydc)] n · 2 n CHCl 3 · n H 2 O ( 3 ), [Cu 2 (bpt)(pydc) 2 (H 2 O) 2 ] n ( 4 ), [Cu 2 (bpt)(pydco) 2 (H 2 O) 2 ] n · n H 2 O ( 5 ) and [Cd(bpt)(pydco)] n ( 6 ) (H 4 pm = pyromellitic acid, H 2 pydc = pyridine-2,6-dicarboxylic acid, H 2 pydco = pyridine-2,6-dicarboxylic acid N -oxide), have been synthesized under the intervention of various polycarboxylate ligands. Complex 1 exhibits a 3-D 4-connected structure with 1-D nanosized open channels encapsulated lots of water molecules. Complex 2 represents a 2-D grid containing two types of rectangular windows. When pydc and pydco instead of pm, complexes 3 and 6 were obtained with highly undulated 2-D layers. The interlayers of 3 are filled with two kinds of solvent molecules, whereas 6 is a double-layered framework without free molecules. Complexes 4 and 5 consist of two distinct 1-D infinite chains held together to form different 2-D supramolecular networks. Importantly, bpt spacer shows changeful conformational geometries and generates complicated crystalline architectures with the introduction of polycarboxylate ligands. Additionally, thermal stability of complexes 1 , 3 and 5 , fluorescent properties of 6 and X-ray powder diffraction of 1 have also been investigated.

Two new isomeric complexes, namely {[Cu(fum)(tpy)] · 5H2O}n (1) and [Cu2(fum)2(tpy)2] · 4H2O (2), have been synthesized simultaneously from the reaction of Cu(fum) with tpy (where fum = fumarate, tpy = 2,2′:6′,2″-terpyridine) under mild condition. The crystal structures of complexes were determined by X-ray single-crystal diffraction. Complex 1 stabilizes in an unusual 1D water tape notated T4(2)10(2), which is directed by two chiral helical water chains; binuclear complex 2 represents a complicated (6, 3)-connected framework via supramolecular interactions. Additionally, complex 1 exhibits weak ferromagnetic behavior.

This work presents a systematic investigation on coordination chemistry of a novel pyridine-2,6-dicarboxylic acid N-oxide (pydco), and also reveals the significant function of supramolecular interactions in dominating the resultant crystalline nets. Assemblies of pydco with transition-metal ions under similar conditions yield a series of polymers in the absence/presence of the organonitrogen ligands {[Cu(pydco)(L)0.5(H2O)] · 2H2O}n (L = bipy (1), bpa (2) and bpe (3)), {[M(pydco)(bpp)(H2O)] · 2H2O}n (M = Cu (4) and Ni (5)), [Ag2(pydco)]n (6) and [Ag2Cu(pydco)2]n (7) (bipy = 4,4′-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethene, bpp = 1,3–bis(4-pyridyl)propane). 1–5 feature different structural characteristics, although they exhibit analogous chain networks. Remarkably, extended architectures are further constructed with the aid of weak interactions. Reaction of pydco with AgAc yields a 2-D polymer 6, which was reported in our recent Communication. A mixed-metal coordination polymer 7 was obtained by the self-assembly of AgAc, Cu(Ac)2 · H2O and pydco. In 7, two left- and right-hand helical chains are constructed by carboxylic groups of pydco and Cu centers, which are further connected by [AgCO2]2 cores into a 2-D network. Structural evolution under the co-ligand intervention in this series of compounds, as well as the general coordination rule of pydco, has been further discussed. Furthermore, variable temperature magnetic properties of 1, 3 and 7 are also studied. The magnetic measurements of 1 and 3 reveal the existence of weak antiferromagnetic interactions with J1 = −4.59 cm−1 and J2 = −4.63 cm−1, respectively. Whereas 7 displays weak ferromagnetic interactions with J3 = 1.81 cm−1.