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A series of nickel dithiolene molecular crystals [Et3N(CH2)3X][Ni(mnt)2] (1: X = H, 2: X = Cl, 3: X = Br and 4: X = I and Br; mnt2− = maleonitriledithiolate) were prepared by introducing triethylpropylammonium derivatives (X–CH2CH2CH2–NEt3+) into [Ni(mnt)2]− building blocks. 1 crystallizes in a monoclinic system with the space group P21/n at 293 K, and the cations and anions in 1 are arranged in columnar segregated stacks along the a-axis direction. Crystals 2 and 3 also belong to monoclinic systems with space groups P21/n and P21/c, but 4 crystallizes in a triclinic system with the space group P1¯. Interactions between [Ni(mnt)2]− ions in all crystals are antiferromagnetic, and the magnitudes of the interactions are qualitatively consistent with the strength of intermolecular interactions estimated from transfer integrals, where interactions between [Ni(mnt)2]− ions are greater than the others in all crystals. The magnetic measurement data demonstrate that antiferromagnetic behavior was observed in 1 and can be fitted well through the 1D alternating linear chain model. Crystal 2 shows spin dimer magnetic behavior, and the magnetic susceptibilities of 3 and 4 show Curie–Weiss-type paramagnetic character in the whole temperature regions. This study showed that halogen substitution on the cations has significant effects on the arrangement and magnetic behavior of [Ni(mnt)2]−. [ABSTRACT FROM AUTHOR]

Herein, two new water-stable magnetic frameworks, [Cu1.5(L)(H2O)]·2H2O (1) and [Co4(L)2(CH3CN)(OH)2(H2O)4]·3H2O (2) (H3L = 5-((4-carboxypyridin-2-yl)oxy) isophthalic acid), were synthesized by a solvothermal method in similar reaction systems and characterized by infrared spectroscopy, powder X-ray diffraction and thermogravimetric measurements. Due to their different metal ions, 1 shows a trinodal (4,4,4)-connected three-dimensional (3D) framework that possesses 1D channels based on [Cu2(COO)4] paddle-wheel secondary building units (SBUs), whereas 2 is a 2D layered network based on tetranuclear [Co4(COO)6(μ3-OH)2] SBUs and reveals a (3,6)-connected kgd topological structure. The gas adsorption explorations demonstrated that 1 exhibited commendable selectivity for CO2 over CH4. Moreover, both 1 and 2 showed different degrees of antiferromagnetic exchange action. [ABSTRACT FROM AUTHOR]

Five new 3D MOFs: {[Zn3(HL)2H2O]·4H2O}n (1), {[Ba2L5H2O]·2H2O}n (2), {[Ba4(L)2·5H2O]·2H2O}n (3), {[Cd3(HL)2·Cl2·2H2O]·2H2O}n (4) and {[Cu2(L)2·2H2O]·4H2O}n (5), were constructed based on 1-(3,5-dicarboxylatobenzyl)-3,5-pyrazole dicarboxylic acid. Structural analysis shows that 1–5 have 3D frameworks, among which 1(Zn) exhibits high luminescence sensing for Fe3+ ions, excellent framework stability and reusability. The sensing mechanism of 1(Zn) is briefly discussed. In addition, 5(Cu) displays antiferromagnetic exchange phenomena. [ABSTRACT FROM AUTHOR]

To better understand the factors determining the multi-step relaxation processes in polynuclear lanthanide single molecule magnets (SMMs), two Dy(iii)4 SMMs showing two-step relaxation processes were elaborately designed and investigated for their structure-dependent magnetic properties. Through targetedly fine-tuning the auxiliary ligand (from the anion of 1-phenylbutane-1,3-dione to 2-acetylcyclopentanone) on specific Dy(iii) sites while retaining the same type of coordination atoms, one of the two relaxation processes shifted to higher temperature with an increase of energy barrier, which permits the unambiguous assignment of the relaxation processes to specific metal sites. Therefore, the present {Dy4} systems provide a good example to probe the factors determining the relaxation dynamics, and point to a simple way to optimize the magnetic performance of polynuclear dysprosium SMMs. [ABSTRACT FROM AUTHOR]

A new ligand, rac-(R,S)-3,9-bis(pyridin-3-yl)-2,4,8,10-tetraoxaspiro[5.5]undecane ((R,S)-bptu), is synthesized, and five novel complexes, namely, {[Cu[(R,S)-bptu]Cl2]·0.5NMP}n (1), {[Zn[(R,S)-bptu]Cl2]·CH3CN}n (2), {Cd2[(R,S)-bptu]2Cl4(NMP)2}n (3), {[Cd[(R,S)-bptu]2Cl2]·2CH3CN}n (4), and {Cd3[(R,S)-bptu]2Cl6(DMF)2}n (5), (NMP = N-methyl-2-pyrrolidone, DMF = N,N-dimethylformamide), are obtained via a layered diffusional reaction. (R,S)-bptu and complexes 1–5 are characterized by single-crystal X-ray diffraction, element analyses, powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). Complexes 1–3 show three different 1D structures: 1 is a mesomeric looped chain, 2 is a racemic helix compound, and 3 is a mesomeric zigzag chain, while 4 and 5 are two different mesomeric 2D structures, of which 4 is a 2D wave-like layer and 5 is a 2D cellular layer. Structural diversity indicates that the coordination preferences (cis- and trans-configurations) of (R,S)-bptu play a leading role in the self-assembly of complexes: cis-bptu tends to form one-dimensional structures 1–3, while trans-bptu is easier to construct higher dimensional structures 4–5. Secondly, the different transition metal atom M(ii) adopts diverse geometry in 1–5: Cu(ii) adopts square pyramidal geometry in 1, Zn(ii) employs a tetrahedron configuration in 2, and especially in 3–5, Cd(ii) displays a trigonal bipyramidal configuration, cis-cis–trans, cis and trans octahedral configuration. Finally, the different solvent system, the coordinated/free solvent, and the secondary building units (SBUs) affect the diversification of the structure. A variable temperature magnetic susceptibility investigation manifests that antiferromagnetic interactions exist between the neighbouring metal ions in 1. Furthermore, the luminescence properties of 2–5 are investigated in the solid state at room temperature, and 4 shows highly selective and sensitive sensing for Fe3+ ions. [ABSTRACT FROM AUTHOR]

By using an asymmetrical rigid pentacarboxylic acid ligand, 2,4-di(3′,5′-dicarboxylphenyl)benzoic acid (H5L), four new three-dimensional (3D) metal–organic frameworks (MOFs), namely {[Cu2(HL)(H2O)2]·2DMF·2H2O}n (1), {[Co2(L)(DMA)]·H2N(Me)2}n (2), {[Co2(L)(H2O)]·H2N(Me)2}n (3), {[Mn2(L)(DMF)(H2O)]·H2N(Me)2}n (4), were solvothermally synthesized. H5L in 1–4 shows different coordination modes and can easily form various metal clusters (secondary building units, SBUs) in the final structures. 1 is a 3D porous framework with a (4,4)-connected pts topology based on the [Cu2(COO)4] paddlewheel SBU, wherein six SBUs are connected by twelve HL4− to get an unprecedented Cu12 hendecahedron nanocage. 2–4 possess similar dinuclear [M2(COO)5] SBUs (M = Co, Mn), which are further extended by L5− to give rise to 3D frameworks with the uncommon (5,5)-connected nia-5,5-P21/c and bnn topologies. In addition, the desolvated framework of 1 contains polar channels decorated with uncoordinated carboxylate groups, leading to selective adsorption for CO2 over CH4 at 195, 273 and 298 K. Moreover, the magnetic properties of 1–4 show that there exist antiferromagnetic interactions between metal ions. [ABSTRACT FROM AUTHOR]

Employing an uninvestigated eight N-donor bitriazole ligand, 5'-(pyrazin-2-yl)-2H,4'H-3,3'-bi(1,2,4-triazole) (H2pzbtz), five complexes, {[Zn2(pzbtz)(SO4)(H2O)2]·2H2O}n (1), {[Cd(pzbtz)]·3H2O}n (2), [Zn3 (Hpzbtz)2(SO4)2(H2O) 6] (3), [Co(Hpzbtz)2(H2O)2] (4) and {[Co2(pzbtz)2(H2O)2]·4H2O}n (5), have been solvothermally synthesised by altering the reaction solvents and temperatures. Complex 1 shows a three dimensional (3D) framework with a very rare (3,5)-connected fsc-3,5-Cmce-2 topology. Complex 2 exhibits a (4,4)-connected 3D pts framework with 1D channels. Complexes 3 and 4 are discrete trinuclear and mononuclear molecules, respectively. Complex 5 presents a chiral 3D framework based on a novel trinuclear Co3 (tr) 4 cluster and features an unusual six-connected lcy topology. In the five complexes, H2pzbtz show a very variety of geometrical configurations and coordination modes. Due to the planarity of H2pzbtz, complexes 1-3 display strong photoluminescence; in particular, 1 features highly selective luminescent sensing for the Cu2+ ion and nitrobenzene molecule. In addition, 2 shows highly selective adsorption for CO2 over CH4, and 5 exhibits antiferromagnetic exchange interactions among the Co2+ ions. [ABSTRACT FROM AUTHOR]