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In this work, an Fe3O triangle based helical chain complex [Fe3(μ3-O)(μ-O2CH)6H2O] was assembled in a solvothermal reaction. The complex was a rare polymeric complex bearing charge separation of Fe3+ and Fe2.5+, in which the charge distribution was like that of magnetite. The valence distribution and polymeric nature result in various magnetism behaviours e.g., ferrimagnetism along the chain, canted antiferromagnetic order, spin-flop and field induced SCM like behavior at low temperature.

Multinuclear hetero-tri-spin complexes based on a methyl-pyrazole nitronyl nitroxide radical, namely, [Ln2Cu3(hfac)12(4-NIT-MePyz)4] (Ln = Gd(1), Tb(2), Dy(3); hfac = hexafluoroacetylacetone; 4-NIT-MePyz = 2-{4-(1-methyl)-pyrazolyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been successfully obtained through a one-pot reaction of the radical ligand (4-NIT-MePyz) with Cu(hfac)2 and Ln(hfac)3. These 2p–3d–4f complexes exhibit five-nuclear structures with the sequence [Cu–Rad–Ln–Rad–Cu–Rad–Ln–Rad–Cu], in which each 4-NIT-MePyz radical acting as a bidentate bridging ligand is coordinated to one Ln(hfac)3 unit through one oxygen atom of the NO groups and to one Cu(hfac)2 unit with one nitrogen atom from the pyrazole ring. For complex 1, based on the spin Hamiltonian calculations and MAGPACK program, it is concluded that there exist ferromagnetic couplings between GdIII and NIT radicals, as well as between CuII and free radicals with J1 = 6.8(1) and J3 = 1.3(2) cm−1, respectively, and antiferromagnetic interactions between radical and radical with J2 = −2.8(5) cm−1. Complex 2 shows frequency-dependent out-of-phase signals under a zero or 2000 Oe dc field indicating single-molecule magnetic behavior.

The combination of LnIII ions (GdIII, TbIII or DyIII) and a pyrazole nitronyl nitroxide radical results in three isomorphous complexes, namely, [Ln(hfac)3(NIT-Pyz)]2 (Ln = Gd(1), Tb(2), Dy(3); hfac = hexafluoroacetylacetone; NIT-Pyz = 2-{3-pyrazolyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide). Single crystal X-ray diffraction studies revealed that all of them are composed of two crystallographically independent mononuclear systems, in which the central LnIII ions are coordinated by three hfac and one bidentate chelating NIT-Pyz radical. The central LnIII ions are all in square antiprism geometry (D4d) polyhedron configurations. Based on the spin Hamiltonian calculations, there exist antiferromagnetic couplings in the GdIII-NIT radical system in complex 1. Complexes 2 and 3 show frequency-dependent out-of-phase signals in a zero field indicating single-molecule magnetic behavior. Moreover, Tb's complex (2) shows a single thermal relaxation process with an energy barrier of 26 K. For Dy's complex (3), the Orbach and Raman processes both contribute to the magnetic relaxation behaviors.

Two methylammonium-templated metal vanadates, namely [CH3NH3]2MV2O7 (M = Mn (1) and Cd (2)), have been solvothermally synthesized and characterized by IR, TGA, UV–Vis, single-crystal X-ray diffraction (XRD) and Powder XRD, etc. These two isostructural compounds feature an open-framework structure constructed by MO6 octahedra and V2O7 dimers. The methylammonium cations are located in the channels of the framework and act as bi-functional charge-compensating and structure-directing agents. Compound 1 exhibits an effective adsorption performance towards Eu3+ by means of ion exchange. Magnetic study reveals the antiferromagnetic exchange between Mn2+ ions in compound 1.

Three oximato-based oligomeric metal complexes, {[Cu3(H2O)(µ3-OH)(mpko)3(NO3)]·3H2O·NO3} (1), {[Cu6(μ3-OH)2(mpko)6(Br)4]·8H2O} (2), and {[Fe3(mpko)6]·ClO4·2.5CH3CN} (3) (mpkoH = 1-(pyrazin-2-yl)ethanone oxime), were synthesized by varying different spin carriers, and structurally and magnetically characterized. Structural determinations reveal that 1 is a discrete triangular {Cu3(μ3-OH)}5+ molecule with two adjacent metal ions further bridged by chelating-bridging mpko− ligands. Complex 2 features a centrosymmetric hexanuclear entity with two triangular {Cu3(μ3-OH)}5+ subunits extended by a pair of bridging μ-Br− anions. By contrast, 3 exhibits an approximately linear trinuclear entity with central FeIII ion connected with two external FeII ions by six crystallographically unique mpko− ligands. Strong antiferromagnetic interactions with the coupling constant up to 223(1) cm−1 are observed in the triangular subunits of 1 and 2. In 3, the central FeIII ion with S = 5/2 is almost magnetically isolate...

Five new nitronyl-nitroxide radical-Ln(III) complexes, [Ln(hfac)3(NITPh-2-OCH2Ph)(IMHPh-2–OCH2Ph)] (Ln = Tb(1), Dy(2)) and [Ln(hfac)3(NITPh-2-OCH2Ph)2] (Ln = Ho(3), Er(4), Yb(5)) (hfac = hexafluoroacetylacetonate, NITPh-2-OCH2Ph = 2-(2-benzyloxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, IMHPh-2-O-CH2Ph = the reduced derivative of NITPh-2-OCH2Ph), have been synthesized and characterized. The single-crystal X-ray diffraction analysis shows that all these complexes crystallize in triclinic P 1 − space group, and are composed of mononuclear molecules. The central Ln(III) ion is eight-coordinated by three bidentate chelating hfac anions and two monodentate NITR (or IMHR) molecules, with a dodecahedron environment. There arise a common interesting structural feature for these complexes that the mononuclear molecules form pseudo-binuclear structures through intermolecular non-covalent N–O⋯O–N contacts of nitroxide groups. All of them show intramolecular weak antiferromagnetic interactions between Ln(III) ion and radicals. Alternating current (ac) magnetic susceptibilities display a frequency-dependent characteristic for both Tb(1) and Dy(2), typical of magnetic slow relaxation of single-molecule magnet (SMM) behavior.

Four magnetic MOFs with anisotropic CoII ions, {[Co5(H2O)2(μ3-OH)2(atz)2(stp)2]·1.5H2O}n (1), {[Co5(H2O)2(μ3-OH)2(trz)2(stp)2]·1.3H2O}n (2), {[Co5(H2O)6(μ3-OH)2(trz)2(stp)2]·2.5CH3OH}n (3) and {[Co3(H2O)4(Hdatrz)2(stp)2]·3H2O}n (4) (stp3− = 2-sulfoterephthalate, trz− = 1,2,4-triazolate, atz− = 3-amino-1,2,4-triazolate and Hdatrz = 3,5-diamino-1,2,4-triazole) were solvothermally isolated by varying the substituent groups appended on the N-heterocyclic triazole and structurally and magnetically characterized. Structural analyses indicate that the former two complexes are crystallographically isostructural, exhibiting pillared-layer frameworks with mixed triazolyl and carboxylate extended CoII4 + CoII1 layers supported by rigid stp3− connectors. Complex 3 is built from butterfly-shaped CoII4 cluster-based layers, which are interconnected with single cobalt(II) octahedra by ditopic stp3− bridges. By contrast, complex 4 consists of linear {Co3(μ-N1,N4-Hdatrz)2} subunits, which are extended by 3-connected stp3− linkers into a stable 3D framework. Magnetically, 1 exhibits ferromagnetic ordering below 2.7 K due to the well-organized alignment of the non-compensated resultant moment from octahedra and tetrahedral cobalt(II) carriers, while 3 is in a non-zero paramagnetic state above 2.0 K resulting from the coexistence of intermetallic ferromagnetic and antiferromagnetic interactions. The magnetic competition between weak inter-subunit antiferromagnetic interactions and the external magnetic field makes 4 behave as a field-induced metamagnet with a critical field of 27.5 kOe. These interesting magnetostructural results suggest that the anisotropy of the moment carrier and the interlayer/intersubunit separations significantly dominate the magnetic responses in extended MOFs, providing an informative platform for the further development of interesting magnetic materials, both of academic and industrial interest.

Four 3,5-diamino-1,2,4-triazole (Hdatrz)-based cobalt(II/III) coordination polymers, {[Co2(Hdatrz)(NH2-ip)2]·0.5H2O}n (1), [Co(CH3OH)(Hdatrz)(CH3-ip)]n (2), {[Co2(datrz)2(CH3-ip)]·2.5H2O}n (3) and {[Co(datrz)(NO2-ip)]·H2O}n (4) (NH2-ip2− = 5-aminoisophthalate, CH3-ip2− = 5-methylisophthalate and NO2-ip2− = 5-nitroisophthalate), were hydro-/solvothermally synthesized by changing the substituents attached on the isophthalate coligand, which were structurally and magnetically characterized. Complex 1 is a corrugated layer with dimeric {Co2(μ-N1,N2-Hdatrz)}4+ subunits extended by three-connected NH2-ip2− connectors. Constructed from the same mixed ligands, both 2 and 3 exhibit robust three-dimensional (3D) frameworks consisting of helical {Co(μ-N1,N4-Hdatrz)}2+ chain and corner-sharing triangular {Co2(μ3-N1,N2,N4-datrz)2}2+ layer, respectively. By contrast, two bis-monodentate NO2-ip2− and two μ-N1,N4-datrz− anions connect tetrahedral Co(III) sites into a (4, 4) grid-like layer of 4. Thus, the substituent of the isophthalate coligand is observed to virtually influence the overall structures of the resulting complexes by changing the binding modes of the coligand and coordination polyhedra. Additionally, complex 1 exhibits a metamagnetic transition from antiferromagnetic ordering to weak ferromagnetic state. Instead, typically antiferromagnetic interactions are respectively mediated by the cyclic triazolate ligand along the helical chain of 2 and in the distorted triangular layer of 3.

The crystal structures and magnetic behaviours of two water-bridged one-dimensional (1D) cobalt(II) chains with different isomeric naphthoate (na(-)) terminals, [Co(H2O)3(2-na)2]n (1) and {[Co(H2O)3(1-na)2]·2H2O}n (2), were reported to investigate the effect of interchain distance on their magnetic properties. Complex 1 with trans-2-na(-) blocks and dense interchain separation exhibits a metamagnetic transition from antiferromagnetic ordering to a saturated paramagnetic phase. By contrast, complex 2 possessing cis-arranged 1-na(-) spacers and good interchain isolation shows unusual single-chain magnetic behavior under a zero dc field. Thus, completely different interchain packing by isomeric naphthoate ligands governs the ratio of intra- to inter-chain magnetic interactions and further results in different magnetic phenomena, which provide significant magnetostructural information on 1D magnetic systems.

Four new 4-amino-1,2,4-triazole (atr)-based coordination polymers, {[Cu2(atr)(H2O)(μ-OH)2(pa)]·H2O}n (), {[Cu3(atr)2(H2O)2(μ-OH)2(npa)2]·2H2O}n (), {[Cu3(atr)5(dca)(μ-OH)(ClO4)2](ClO4)2}n () and {[Cu3(atr)2(H2O)(μ3-OH)(μ-OH)2(spa)]·1.5H2O}n () (pa(2-) = phthalate, npa(2-) = 3-nitrophthalate, dca(-) = dicyanamide and spa(3-) = 4-sulfophthalate), were successfully obtained by varying the carboxylate- and cyanide-modified magnetic bridges. Structural determinations reveal that the former three samples are bent one-dimensional chains constructed from linear Cu(II)3 subunits and different inter-subunit connections. In , linear {Cu3(μ-N1,N2-atr)2(μ-OH)2}(4+) and {Cu3(μ-COO)2(μ-OH)2}(4+) subunits are alternately connected in a sharing-vertex manner to give a ferrimagnetic S = 1/2 spin ground-state. The linear {Cu3(μ-N1,N2-atr)2(μ-OH)2}(4+) building block of is repeatedly bridged by pairs of single-atom bridging carboxylate groups of the npa(2-) ligand leading to a paramagnetic S = 1/2 spin ground-state. By contrast, each linear {Cu3(μ-N1,N2-atr)4}(6+) core in is periodically propagated by four-fold heterobridges (μ-OH(-), μ-ClO4(-), μ-N1,N2-atr and μ-dca(-)) to generate an overall diamagnetic S = 0 spin ground-state. Complex is a three-dimensional pillared-layer framework composed of linear {Cu3(μ-N1,N2-atr)2(μ-OH)2}(4+)-based layers and ditopic spa(3-) connectors, which exhibits a ferrimagnetic S = 1/2 spin ground-state and a metamagnetic transition resulting from the competition between the weak interchain/interlayer antiferromagnetic interaction and the enhanced external magnetic field. In addition, different intra- and inter-subunit magnetic strengths are observed in with the coupling constants 182-Jintra43 and -127Jinter51.2 cm(-1). These interesting magnetostructural results are significant and helpful for the cyclic polyazolate-based magnetic materials.

Three one-dimensional metal–nitroxide complexes [Cu(NIT4Py)2(1,4-chdc)] n (1), {[Cu(IM4Py)2(1,4-chdc)(H2O)]·H2O} n (2) and {[Zn(IM4Py)2(1,4-chdc)(H2O)2]·H2O} n (3) (NIT4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, IM4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and 1,4-chdc = 1,4-cyclohexanedicarboxylate anion) have been synthesized and characterized structurally as well as magnetically. All three complexes crystallize in neutral one-dimensional chains in which the nitroxide–metal–nitroxide units are linked by linear 1,4-cyclohexanedicarboxylate anions. The 1,4-chdc ligands only present the e,e-trans-configuration in these complexes, although there are both cis- and trans-isomers in the free ligand. Magnetic measurements show that complexes 1 and 2 both exhibit weak antiferromagnetic interactions between the copper atoms and nitroxide radicals.

Two novel two-dimensional copper–nitroxide coordination polymers of formula [Cu2(NIT3Py)2(glu)2]n (1) and {[Cu2(NIT3Py)2(adip)2] · CH3OH · 0.5H2O}n (2) (NIT3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, H2glu = glutaric acid and H2adip = adipic acid), have been synthesized and characterized structurally as well as magnetically. The crystal structures of both polymers contain the paddle-wheel binuclear Cu(II) units axially coordinated by NIT3Py ligands which are bridged by the flexible glutarate or adipate anions into the corrugated 2D sheets. Interestingly, complex 1 displays a 2D helical layer structure rarely found in metal–nitroxide systems. The magnetic measurements show the strong antiferromagnetic interactions in the binuclear Cu(II) units and weak antiferromagnetic interactions between copper ions and nitroxides.

Four 3-amino-1,2,4-triazole (atz)-based magnetic complexes, {[Mn2(atz)2(nip)2]·2H2O}n (1), {[Mn2(atz)2(Hbtc)2]·2H2O}n (2), [Mn3(atz)2(H2O)12(btc)2] (3), and {[Mn2(atz)(H2O)4(btec)]·2H2O}n (4), (nip2− = 5-nitroisophathalate, btc3− = 1,3,5-benzenetricarboxylate, and btec4− = 1,2,4,5-benzenetetracarboxylate), have been respectively prepared by increasing the numbers of the carboxylate group appended on the phenyl backbone, which were structurally and magnetically characterized by single-crystal and powder X-ray diffraction, elemental analysis, FT-IR spectra, thermogravimetric and magnetic measurements. Structural determinations reveal that complexes 1 and 2 with different polycarboxylate coligands are isostructural, exhibiting 4-connected CdSO4-type frameworks with dimeric MnII2 subunit extended by ditopic μ-N1,N4-atz and carboxylate-containing connectors. In contrast, complex 3 that assembled from the same components as 2 is a discrete trinuclear entity aggregated by two μ-N2,N4-atz ligands. Complex 4 has a layered motif with bent MnII-btec4− ribbons interconnected by μ-N2,N4-atz ligands. Weak antiferromagnetic interactions with comparable coupling constants transmitted by μ-syn, anti-COO− and/or μ-N2,N4-atz mediators were respectively observed in the nearest neighbours of the local bi- and trinuclear magnetic subunits of 1–4.

Three 3-amino-1, 2, 4-triazole (atz)-based paramagnetic complexes, [Mn(atz)(pa)]n (1), {[Mn(atz)1.5(hip)]·H2O}n (2), and [Mn(H2O)2(atz)2(nb)2] (3) (H2pa = o-phthalic acid, H2hip = 5-hydroxylisophthalic acid, and Hnb = p-nitrobenzoic acid) were prepared by introducing different carboxylate-containing aromatic coligands, and structurally and magnetically characterized. Helical MnII-atz and bent MnII-pa2– chains are crosslinked by sharing the same metal sites to generate a honeycomb-shaped framework of 1. The undulated MnII-atz layers constructed from 22-member metallomacrocycles are periodically supported by ditopic hip2– ligands to lead to a pillared-layer structure of 2. In contrast, complex 3 is a centrosymmetric mononuclear entity, which is assembled into a three-dimensional supramolecular network by abundant hydrogen-bonding interactions. The structural difference of 1–3 is significantly due to the combinations of the flexible coordination modes adopted by the mixed atz and carboxylate groups. Weak and comparable antiferromagnetic couplings are observed in the nearest neighbors of 1–3, which are cooperatively transmitted either by short carboxylate and/or atz heterobridges or by weak non-covalent interactions.

Three new MOFs with the same components but different structures and magnetic behavior, {[Cu6(atr)6(H2O)2(µ3-OH)2(SO4)5]·5.25H2O} n (1), {[Cu2(atr)2(µ-OH)2(SO4)]·3H2O} n (2), and {[Cu7(atr)6(H2O)6(µ3-OH)2(SO4)6]·2H2O} n (3) (atr = 4-amino-1,2,4-triazole), were respectively synthesized by diffusion reactions in the presence of different structure-directing agents. Complex 1 is a slightly spin-frustrated antiferromagnetic layer with sulfonate aggregated CuII 6 clusters periodically extended by ditopic sulfonate linkers. 2 is a grid-based coplanar sheet with hydroxyl group bridged -CuOCu- linear-chain interlinked by pairs of µ3-atr ligands, exhibiting strong antiferromagnetic interactions to lead to an S = 0 spin ground state at low temperature. In contrast, air-instable 3 has a ladder-like broad-ribbon structure constructed from triangular CuII 3 cores and centrosymmetric CuII 1 octahedra. Obviously, the variable CuII-ligand connectivity and the involving magnetic properties are significantly dominated by the cooperative and variable binding modes of the mixed sulfonate-atr ligands and bi-/tridentate bridging hydroxyl heterobridges.

Four magnetic samples with different building blocks and dimensionalities, {[Cu(4)(atr)(2)(μ(3)-OH)(2)(sip)(2)]·4H(2)O}(n) (1), {[Cu(4)(atr)(2)(H(2)O)(8)(μ-OH)(2)(sip)(2)]·1.3CH(3)OH·0.7H(2)O}(n) (2), {[Cu(3)(atr)(4)(H(2)O)(2)(sip)(2)]·4H(2)O}(n) (3) and {[Cu(3)(atr)(4)(H(2)O)(2)(μ(3)-OH)(sip)(Hsip)]·2CH(3)OH·2.75H(2)O}(n) (4) (atr = 4-amino-1,2,4-triazole and sip(3-) = 5-sulfoisophthalate), were obtained and characterized structurally and magnetically. Complex 1 exhibits a three-dimensional (3D) robust framework with butterfly-like Cu(II)(4) clusters periodically extended by tetratopic sip(3-) connectors. Complex 2 possesses a 2D layer with alternating Cu(II)(3) + Cu(II)(1) chains crosslinked by pairs of ditopic sip(3-) linkers. By contrast, the latter two entities feature 1D broad ribbons with linear (for 3) and triangular Cu(II)(3) cores (for 4) propagated by bidirectional sip(3-) connectors. Structural analysis reveals that the diverse building blocks and dimensionalities of 1-4 are significantly dominated by the tunable coordination of exocyclic amino- and/or sulfonate-group of the mixed ligands. Magnetically, antiferromagnetic interactions with variable strength transmitted by -NN- moiety of atr and hydroxyl mediators result in overall S = 0 (for 1) and 1/2 (for 3 and 4) spin ground states. These interesting results indicate that coordinative side group in the ternary metal ion-azolate-carboxylate system can be utilized to generate aesthetically pleasing building units and variably polytopic connectors, leading to differently extended superstructures and magnetic behavior.

Three new CuII cluster-based magnetic complexes with the same components but different structures and magnetic behavior, [Cu4(atr)2(μ3-OH)2(btc)2]n (1), {[Cu3(atr)6(H2O)2(H2btc)2]·4H2btc·11H2O·DMF}n (2), and [Cu3(atr)6(Hbtc)2(H2btc)2]·2H2O (3) (atr = 4-amino-1,2,4-triazole and H3btc = 1,3,5-benzenetricarboxylic acid), were synthesized by varying the preparation methods and fully characterized. Significantly due to the deprotonation extent-dependent binding modes of the aromatic tricarboxylic acid coligand, the former two complexes exhibit polymeric structures with a butterfly-shaped CuII4 cluster-based rtl-type framework for 1 and a linear CuII3 subunit-derived coplanar layer for 2, and the last one is a discrete linear CuII3 entity blocked by the terminal tricarboxylate groups. The cooperative antiferromagnetic and ferromagnetic nearest-neighbor interactions mediated by the differently four-fold heterobridges in the local CuII4 cluster result in an S = 0 ground state of 1. Instead, the central CuII ion in the linear CuII3 subunit is antiferromagnetically coupled with its two external ones through triple μ-κ2N1:N2-atr homobridges to lead to an S = 1/2 ground state of 2 and 3.

A 3D pillared-layer porous framework, {[Co2(H2O)(μ3-OH)(ptz)(nip)]·2H2O}n (1) (ptz = 5-(4-pyridyl)tetrazolate, nip = 5-nitroisophthalate), was in situ hydrothermally synthesized and structurally and magnetically characterized. Interestingly, the layered substructure of 1 consists of scarcely observed corner-sharing Co2(μ3-OH) ∆-chain and unprecedented pentadentate ptz ligand. More importantly, due to the mixed triple syn,syn-carboxylate-μ3-OH-μ4-tetrazolyl bridges as well as the triangular CoII arrangement, 1 behaves as a typical antiferromagnetically coupled paramagnet with a slight spin frustration, which exhibits a low-dimensional antiferromagnetic ordering below 10 K (Neel Temperature).

Two 3-amino-1,2,4-triazole (Hatz)-based magnetic complexes, {[Mn3(H2O)2(Hatz)2(sip)2]·2H2O}n (1) and {[Mn(H2O)3(Hatz)(bda)]·H2O}n (2) (sip3− = 5-sulfoisophthalate and bda2− = trans-butenedioate), were respectively prepared by varying dicarboxylate-containing coligands, and were structurally and magnetically characterized. Structural determinations reveal that 1 exhibits a two-dimensional layered structure with linear {Mn3(μ-N1,N2-Hatz)2}6+ subunits extended by tritopic sip3− connectors. By contrast, 2 is an infinite zigzag chain constructed from octahedral Mn(II) ions and μ-N1,N4-Hatz linkers. Magnetically, typically antiferromagnetic interaction observed in the local MnII3 subunit of 1 mediated by mixed μ-syn, syn-COO− and μ-N1,N2-Hatz heterobridges is slightly stronger than that of 2 transmitted by single μ-N1,N4-Hatz mediator.

Four tetrazolate (tz(-))-based magnetic metal-organic frameworks, [Cu5(μ3-OH)2(SO4)2(tz)4]n (), {[Cu3(tz)4Cl2]·1.4CH3OH}n (), [Cu(N3)(tz)]n () and {[Cu5(tz)9]Cl·4H2O}n (), were hydro/solvothermally synthesized, and structurally and magnetically characterized. Structural analyses reveal that the former two samples exhibit the same eight-connected topological framework assembled from different subunits. Hourglass-shaped {Cu5(μ3-OH)2}(8+) cores in are periodically extended by mixed μ3-/μ4-tz(-) and μ4-SO4(2-) heterolinkers, while the linear {Cu3(μ-Cl)2}(4+) blocks in are repeatedly intersected by ditopic μ3-tz(-) connectors. In contrast, the square grid-shaped network of is constructed from linear {Cu(μ1,1-N3)}(+) chains and μ3-tz(-) linkers. Complex consists of trigonal-prismatic {Cu8(μ3-tz)6}(10+) subunits, which are interlinked into hexagonal microporous architecture by mirror-symmetry μ4-tz(-) ligands. Thus, the various subunits of are significantly tuned by the co-coordination of the inorganic anions and/or the azido co-ligand, and the backbone extensions are directed by the polytopic tetrazolate ligand. Magnetically, different ordering arrangements of the non-zero magnetizations produced in the local Cu(II)5 and Cu(II)3 subunits eventually lead to unusual ferrimagnetic and canted antiferromagnetic properties in and . Strong antiferromagnetic couplings mediated by the mixed tz(-) and/or azido bridges result in overall S = 0 spin ground-states of and .

Self-assembly from the predesigned Cu(II)5 secondary building unit (SBU) in the ternary Cu(II)-triazolate-sulfoisophthalate system generates three interesting magnetic samples: an open pillared-layer framework with nanosized Cu(II)30 metallamacrocycle-based sublayer (1), a (3,6)-connected 2-fold interpenetrating network consisting of alternating Cu(II)5 and Cu(II)1 cores (2), and a (4,8)-connected architecture constructed from centrosymmetric Cu(II)7 clusters and four-branched 5-sulfoisophthalate (sip(3-)) connectors (3). These various structures significantly result from the variable connectivity and the slight expansion of the predetermined conformationally flexible Cu(II)5 SBUs. Furthermore, these intriguing structural motifs in 1-3 essentially induce different magnetic phenomena. A field-dependent metamagnetic transition from antiferromagnetic ordering to weak ferromagnetism is observed in the frustrated Cu(II)30-based sublayer of 1. The paramagnetic Cu(II)1 core in 2 virtually contributes to an S = (1)/2 spin ground state due to the completely compensated magnetic moment in the 1,2,3-triazolate (ta(-))-bridged Cu(II)5 cluster containing ribbon. In contrast, strong antiferromagnetic interactions in the locally centrosymmetric Cu(II)7 cluster lead to an overall S = (1)/2 spin ground state of 3. Thus, the SBU-derived self-assembly strategy provides important hints for polymetallic cluster based high-dimensional magnetic materials, which also brings a new vision for the design and construction of novel functional materials.

Three extended three-dimensional (3D) magnetic metal-organic frameworks (MMOFs), {[Mn3(H2O)2(atz)4Cl2]·2CH3OH}n (1), {[Mn2(H2O)(atz)2(ip)]·C2H5OH}n (2) and {[Mn2(H2O)2(atz)(btc)]·3H2O·0.7CH3OH}n (3) (atz(-) = 5-aminotetrazolate, ip(2-) = isophthalate and btc(3-) = 1,3,5-benzenetricarboxylate), were respectively obtained by varying the coligands with different numbers of functionalities and molecular topology, and structurally and magnetically characterized. Complex 1 exhibits an eight-connected 3(6)·4(18)·5(3)·6 topological network with linear Mn(II)3 subunits periodically linked by ditopic atz(-) connectors. Complex 2 possesses a pillared-layer framework constructed from undulated {Mn2(atz)2} layers and bidirectional ip(2-) spacers. By contrast, 3 consists of bent one-dimensional (1D) {Mn(atz)} ribbons, which are crosslinked through the carboxylate groups of tripodal btc(3-) connectors to generate a 3D architecture. Structural analysis reveals that the interesting motifs of 1-3 and their diverse linkages are significantly dominated by the cooperate coordination of the mixed ligands to the octahedral Mn(II) ion. Magnetically, 1 displays ferrimagnetic behavior resulting from the periodic arrangement of the net moment in the Mn(II)3 subunit, which is scarcely observed in the homometallic azolate systems. Complex 2 features unusual coexistence of spin-canted antiferromagnetic behavior and field-induced spin-flop transition due to the asymmetric magnetic superexchange within the two-dimensional (2D) {Mn2(atz)2} sublayer. By contrast, only antiferromagnetic ordering is observed in the 1D {Mn(atz)} ribbon of 3. These interesting results suggest that the diverse structural motifs by the cooperate coordination of octahedral Mn(II) ion with the N-rich tetrazolyl group can more significantly direct the magnetic behaviors and could be hopefully utilized upon the construction of novel MMOFs.

Two carboxylate-bridged Dy(III) complexes, [Dy(2)(piv)(5)(μ(3)-OH)(H(2)O)](n) (1) and [Dy(2)(piv)(6)(phen)(2)] (2) (pivH = pivalic acid; phen = 1,10-phenanthroline), have been synthesized and structurally characterized. Complex 1 takes a one-dimensional (1D) chain structure based on [Dy(4)(μ(3)-OH)(2)(piv)(8)(H(2)O)(2)](2+) units, while complex 2 is a dinuclear structure bridged by syn,syn-carboxylates. Magnetic investigation indicates weak ferromagnetic interaction between adjacent Dy(III) ions of the Dy(4) unit in 1 and weak intramolecular antiferromagnetic interaction between Dy(III) ions and/or depopulation of the Dy(III) excited-state Stark sublevels in 2. Alternating-current susceptibility measurements revealed frequency- and temperature-dependent out-of-phase signals under a zero direct-current field in 1, with typical slow magnetic relaxation behavior with an anisotropic barrier U ≈ 4.5 K, while 2 exhibits field-induced single-molecule-magnet behavior with ΔE/k(B) = 28.43 K under a 2 kOe external field.

A (3, 4, 14)-connected framework with complicated distorted triangular magnetic lattices, {[Co(7)(H(2)O)(4)(trz)(8)(sip)(2)]·3H(2)O}(n) (trz = 1,2,4-triazolate, sip = 5-sulfoisophthalate), exhibits continuous field-induced metamagnetic transition from an antiferromagnetic ordering to a ferrimagnetic state at 15 kOe, spin competition at 26 kOe and spin reorientation at 50 kOe, respectively.

A magnetic isolated chain-based substituted cobalt-formate framework was obtained with isonicotine as a spacer. In the chain, canted antiferromagnetic interactions exist in between the Co(II) ions, and slow magnetic relaxation is detected at low temperature. For the block effects of the isonicotine ligands, the complex could be considered as a peculiar example of a weak ferromagnetic single-chain-magnet.

Three new paramagnetic ion-directed coordination frameworks, {[Co(4)(H(2)O)(2)(μ(3)-OH)(2)(atz)(2)(nip)(2)]·3H(2)O}(n) (1), {[Mn(4)(H(2)O)(2)(μ(3)-OH)(2)(atz)(2)(nip)(2)]·H(2)O·MeOH}(n) (2) and {[Cu(2)(H(2)O)(μ(3)-OH)(atz)(nip)]·2H(2)O}(n) (3), were, respectively, obtained by solvo-/hydrothermal reactions of 5-amino-1H-tetrazole (Hatz), 5-nitroisophathalic acid (H(2)nip) with an inorganic Co(II), Mn(II) or Cu(II) salt. The former two complexes are two-dimensional (2D) covalent layers built from butterfly-shaped tetranuclear M(4)(μ(3)-OH)(2) clusters and double atz(-) and nip(2-) linkers. Whereas complex 3 is a 3D framework with scarcely observed corner-sharing Cu(3)(μ(3)-OH) Δ-chains extended by nip(2-) linkages, in which the anionic atz(-) ligand acts as a reinforcement to consolidate the Δ-chain. Magnetically, due to the interplay of the anisotropy of spin carrier and magnetic exchange interactions from the adjacent spin carriers, the complexes exhibit spin-canted antiferromagnetism with a Neel temperature lower than 2.0 K for 1 and an antiferromagnetic ordering with a slight field-induced spin-flop transition for 2. In contrast, complex 3 with a local Kagome sublattice displays spin-frustrated antiferromagnetic behavior with magnetic ordering at 16.0 K.

Three novel 3,5-diamino-1,2,4-triazole (Hdatrz)-based Co(II) coordination complexes, [Co(Hdatrz)(0.5)(H(2)O)(2)(btec)(0.5)](n) (1), {[Co(Hdatrz)(Hbtc)]·H(2)O}(n) (2) and [Co(2)(datrz)(2)(nb)(2)](n) (3) (H(4)btec = 1,2,4,5-benzenetetracarboxylic acid, H(3)btc = 1,3,5-benzenetricarboxylic acid and Hnb = 4-nitrobenzoic acid), were synthesized by incorporating different carboxylate-containing co-ligands and then were structurally and magnetically characterized. Complex 1 is a 3D pillared-layer framework with corrugated Co(II)-btec(4-) layers supported by neutral μ(2)-N1, N4-Hdatrz ligands. In contrast, the other two complexes are chiral (4, 4)- and racemic (4, 8(2))-topological layers with asymmetric μ(2)-N1, N4-Hdatrz-bridged helical chains extended by bis-monodentate Hbtc(2-) ligands for 2 and with a μ(3)-N1, N2, N4-datrz((-)) aggregated Shastry-Sutherland magnetic layer for 3. More interestingly, different magnetic phenomena with a field-induced metamagnetic transition from antiferromagnetic ordering to a ferromagnetic state for 1, spin-canted antiferromagnetism with a T(N) lower than 2.0 K for 2, as well as the coexistence of spin frustration and spin-flop transitions for 3 were observed, which, significantly, are governed by the local low-dimensional magnetic motifs mediated by the carboxylate and/or triazolate heterobridges in the anisotropic Co(II)-triazolate system.

Two 3D coordination polymers with the same components but different structures, [Cu(II)(2)Cu(I)(trz)(3)(Hbtc)](n) (1) and [Cu(4)(Htrz)(2)(mu(3)-OH)(2)(btc)(2)](n) (2), were obtained together by a one-pot hydrothermal reaction of Cu(OAc)(2).H(2)O, 1,2,4-triazole (Htrz), and 1,3,5-benzenetricarboxylic acid (H(3)btc). Complex 1 is a mixed-valence Cu(I/II) honeycomb built from wavy Cu(II)-trz-carboxylate layers and Cu(I) nodes with doubly deprotonated Hbtc(2-) ligands covalently filled in the channels. In contrast, 2 is a tetranuclear [Cu(4)(Htrz)(2)(mu(3)-OH)(2)](6+) cluster-based framework extended by a fully deprotonated btc(3-) ligand, displaying a 3,6-connected topological network. More interestingly, spin-canted antiferromagnetism and overall strong antiferromagnetic couplings up to -147.1 cm(-1) are respectively observed for 1 and 2, which are significantly due to the antisymmetric magnetic exchange in the wavy Cu(II)-trz-carboxylate sublayer of 1 and the cooperative 4-fold heterobridges within the tetranuclear cluster of 2.

A [Co(6)(μ(3)-OH)(4)(datrz)(2)](6+) ribbon-based blue framework with a metamagnetic transition from an antiferromagnetic ordering to a weak spontaneous magnetization state, {[Co(3)(CH(3)OH)(μ(3)-OH)(2)(datrz)(sip)]·2.25H(2)O}(n) (1, Hdatrz = 3,5-diamino-1,2,4-triazole, sip(3-) = 3,5-dicarboxybenzenesulfonate), was solvothermally synthesized. 1 exhibits a reversible single-crystal-to-single-crystal transformation by solvent exchange to generate a pink antiferromagnetic ordering coordination layer with a similar [Co(6)(μ(3)-OH)(4)(datrz)(2)](6+) ribbon to 1, {[Co(3)(H(2)O)(3)(μ(3)-OH)(2)(datrz)(sip)]·2.125H(2)O}(n) (2). Such concomitant solvatochromic and solvatomagnetic effects are scarcely observed and are significantly due to the coexistence of differently distorted metal coordination spheres and the cleavage/generation of the weak coordination bond.

Two new 3-amino-1,2,4-triazole (amtrz)-based 3D MOFs, [Cu4(amtrz)2(μ3-OH)2(btc)2]n (1), and [Cu5(amtrz)2(H2O)2(μ3-OH)2(btec)2]n (2) (btc3− = 1,3,5-benzenetricarboxylate and btec4− = 1,2,4,5-benzenetetracarboxylate), were hydrothermally synthesized and structurally and magnetically characterized. Each cationic [Cu4(amtrz)2(μ3-OH)2]6+ cluster in 1 is periodically extended into an infinite 3,6-connected rtl-type topological network via six btc3− ligands. In contrast, analogous CuII4 clusters to 1 and square-planar CuII1 cores in 2 are alternately interlinked through btec4− linkers to generate a 3D (44·62)2(46·64)4(48·66·8)3 framework, which is a scarcely observed higher-dimensional coordination polymer with a CuII4 + CuII1 motif. More interestingly, both the coordination polymers display strong antiferromagnetic couplings up to −154.6 cm−1 due to the favorable multiple heterobridges in the analogous CuII4 component.

A novel 3D framework with vertex- and edge-sharing Δ-ribbons extended by ip(2-) connectors, {[Co(7)(H(2)O)(2)(μ(3)-OH)(4)(atz)(2)(ip)(4)]·5H(2)O}(n) (atz(-) = 5-amino-tetrazolate and ip(2-) = isophthalate), exhibits a two-step field-induced metamagnetic transition from an antiferromagnetic ordering to a weak spontaneous magnetization state by spin-competition at 2.0 KOe, followed by a spin-flop transition at 22.5 KOe.

Four ligand-deprotonation induced coordination polymers, {[Cu4(atr)4(H2O)2(btec)2]·2.5H2O}n (1), {[Cu3(atr)4(H2O)2(μ3-OH)(Hbtec)]·2ClO4·2H2O}n (2), [Cu(atr)2(H2O)(H2btec)]n (3), and [Cu(atr)2(H2O)2(H2btec)]n (4) (atr = 4-amino-1,2,4-triazole and H4btec = 1,2,4,5-benzenetetracarboxylic acid), were obtained by delicate tuning of the pH value of the reactant mixture. All compounds have been structurally and magnetically characterized. The competitive bridging roles of the two different ligands as well as the degree of deprotonation of the aromatic tetracarboxylic ligand resulted in the formation of four different networks: a coplanar CuII4 cluster-based 3D framework for 1, triangular CuII3-core-derived 2D layers for 2, and H2btec2−-bridged 1D zig-zag or linear chains for 3 and 4, respectively. Magnetic measurements reveal antiferromagnetic couplings with variable strength ranging from −188.9 to −0.712 cm−1 within the isolated CuII4, CuII3, and H2btec2−-bridged CuII nodes in 1–4. These couplings are essentially determined by the spatial orientation and coordination characteristics of the homo- and heterobridges between the adjacent spin carriers.