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Various naphthalenediimide (NDI) based electron donor–acceptor coordination polymers (D–A CPs) have been constructed and used to explore charge transfer (CT) and electron transfer (ET) behaviors. Up to now, significant progress has been made in the interface contact and electron donor–acceptor ability matching mechanism, while the electronic density effect of the electron donors on the CT and ET behaviors is still not known. Herein, two NDI-based D–A CPs, [Cd2(H2NDI)(IPA)2(H2O)2] (1) and [Cd2(H2NDI)(IPA-OH)2(H2O)2] (2), are constructed using an NDI-based ligand and two aromatic carboxylic acid ligands (H2NDI = 2,7-bis(3,5-dimethyl) dipyrazol-1,4,5,8-naphthalene tetracarboxydiimide, H2IPA = isophthalic acid; and H2IPA-OH = 5-hydroxyisophthalic acid). UV-vis and EPR spectroscopy and DFT calculations analyses reveal that the occurrence of themal electron transfer (TET) in 1 and 2 results from the HOMO of the IPA and IPA-OH lying higher than the LUMO of the NDI. Meanwhile, compared to 1, the UV-vis absorption spectrum of 2 exhibits a significant red shift, which suggests higher electron density of the donor and more electron transfer pathways are beneficial for the occurrence of intermolecular CT. After UV light irradiation, the comparison of the photochromic behavior of 1 and 2 confirms the negative effect of the stronger CT on photoinduced electron transfer (PET). The present study illustrates the delicate modulating effect of electron density on the CT and ET behaviors in D–A CPs. [ABSTRACT FROM AUTHOR]

Tuning the emissive color changes of lanthanide (Ln) complexes is an important and appealing project for promoting the applications of Ln-complexes. A solvothermal reaction of 4-cyano-3-methylbenzoic acid (HL) and Ln(NO3)3·6H2O affords three isostructural Ln-complexes [Eu(L)3(H2O)2]n (1-Ln) (Ln = Eu, Gd and Tb) with one-dimensional chain structures. 1-Eu and 1-Tb show bright red and green emissions with absolute quantum yields of 3.06% and 11.96%, respectively, and the energy transfer was analyzed in detail through combined calculations. Interestingly, a series of heterometallic doped 1-TbxEu1−x coordination polymers were also obtained by mixing different ratios of Eu3+ and Tb3+ ions, which possess continuous luminescent color changes from green to yellow, orange and red. In addition, 1-Eu exhibits high quenching efficiency and low detection limit (∼10−4 M) for the simultaneous sensing of MnO4−, CrO42− and Cr2O72− ions in water. [ABSTRACT FROM AUTHOR]

The discharge of excessive metal ions and anions into water bodies leads to the serious pollution of water and environment, which in turn has a certain impact on industry, agriculture, and human life. Because of the unique advantages of luminescent metal–organic frameworks (LMOFs), they have been successfully explored as various fluorescent probes to quickly and effectively detect these pollutants. This perspective not only introduces the design strategy and classification of LMOFs, especially the construction methods of water-stable LMOFs, but also reports the latest progresses in some LMOFs between 2016 and 2020 as well as expounds the mechanisms of LMOFs for detecting anions and cations. Moreover, the luminescence properties of LMOFs are related to the selection of metal ions, the structure of organic ligands, the pore size, and the interaction of guest molecules. Finally, the further development of LMOFs is summarized and prospected in this field. [ABSTRACT FROM AUTHOR]

A mixed-ligand strategy has been used to construct stable luminescent coordination polymers (CPs). An ultra-stable Zn(II) coordination polymer, [Zn(H3tpb)(Hbtc)]n (1) was hydrothermally synthesized by employing a new tripodal pyrazole ligand H3tpb and a classical carboxylic ligand H3btc (H3tpb = 1,3,5-tris(pyrazolyl)benzene, H3btc = 1,3,5-benzenetricarboxylic acid). Complex 1 exhibits a 2D sql network. Importantly, 1 not only possesses excellent thermal stability but also shows superior chemical stability in terms of water resistance, acid/base aqueous solutions tolerance (pH = 2–12), and organic solvents resistance. This excellent structural stability was further illustrated from the perspective of thermal decomposition kinetics. The luminescence properties were investigated, showing that complex 1 displays high sensitivity and selectivity for detecting Fe3+ and Cr2O72− ions in aqueous solutions via luminescence quenching effects. [ABSTRACT FROM AUTHOR]

Mixed transition metal oxides with favorable electrochemical properties are promising electrode materials in energy storage and conversion systems. In this work, uniform porous yolk--shell MnCo2O4 (denoted as YSM-MCO) microrugby balls have been synthesized by simple annealing treatment of metal carbonates with a microrugby ball shape in air. Benefiting from the desired porous structure and composition, the assynthesized YSM-MCO exhibits enhanced electrochemical performance when investigated as anode materials for lithium-ion batteries and electrocatalysts for the oxygen evolution reaction. The YSM-MCO demonstrates remarkable lithium storage properties with a good cycling stability (94% capacity retention over 200 cycles at 0.5 A g-1) and superior rate capability (414 mA h g-1 at 5 A g-1). In addition, the YSM-MCO also exhibits better OER activity than most of the reported MnCo2O4-based electrocatalysts. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) porous Mn(ii)-based metal–organic framework [Mn4(L)2(H2O)4]n·4DMF·H2O (1) has been synthesized using Mn(ii) and the rigid 2,6-di(2′,5′-dicarboxylphenyl)pyridine (H4L) ligand under solvothermal conditions. Structural analysis revealed that MOF 1 is an open framework with exposed active nitrogen atoms and rectangular-shaped channels along the b axis (with effective aperture sizes of 11.3 × 8.8 Å2 and 10.7 × 8.7 Å2). Gas sorption behaviors showed that MOF 1 has a relatively high capacity and selectivity for CO2 over CH4. Thus, the CO2 cycloadditions were studied using different epoxides, displaying the high efficiency of the catalyst. It was also found that MOF 1 shows rapid adsorption for the organic dyes. Therefore, MOF 1 should be explored as a multifunctional porous material for gas separation, catalysis and dye adsorption. [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]

A dynamic guest-binding study of BODIPY-derivative 3 (3 = 1,3,5,7,8-pentamethyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) with two Cp*RhIII-based organometallic cages [Cp*6Rh6(μ-CA)3(tpt)2](OTf)61 (H2CA = chloranilic acid, tpt = 2,4,6-tripyridyl-1,3,5-triazine) and [Cp*6Rh6(μ-DHNA)3(tpt)2](OTf)62 (H2DHNA = 6,11-dihydroxynaphthacene-5,12-dione) have been demonstrated. While guest 3 displays a strong green fluorescence emission, the host–guest complexes 3⊂1 and 3⊂2 exhibit almost no emission. However, fluorescence emission can be again ‘turned on’ by adding coronene (4) or pyrene (5) into the solution of 3⊂1 and 3⊂2. Guests 4 and 5 show stronger binding affinities toward the organometallic cages 1 and 2 due to the strong electrostatic interactions between the electron-rich guest and electron-deficient tpt resulting in the displacement of 3 by 4 or 5, which eventually helps the fluorescence enhancement. Further guest-binding studies using a Job's plot experiment illustrate the formation of discrete 1 : 1 host–guest complexes which are also supported by 1H NMR spectroscopy and ESI mass spectrometry. The anion-exchange study with sodium chloride reveals that the chloride ion can effectively disassemble the host frameworks of 1 and 2 releasing the fluorescent guest 3 which can be again encapsulated into the cavity of reassembled cages promoted by the addition of silver triflate. [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]

The study of mononuclear lanthanide-based systems, where the observed Single Molecule Magnets (SMMs) properties originate from the local magnetic anisotropy of the single lanthanide ion, has been extensively investigated in the literature. The case for polynuclear lanthanide SMMs becomes more challenging both experimentally and theoretically due to the complexity of such architectures involving interactions between the magnetic centers. Much interest was devoted to the study of the structural effect on the magnetic interactions and relaxation dynamics. However, the understanding of the structural influence on those two factors remains a difficult task. To address this issue, a system containing two structurally related tetranuclear Dy(iii) SMMs, namely [Dy4(L)4(OH)2(DMF)4(NO3)2]·2(DMF)·(H2O) (1) and [Dy4(L)4(OH)2(DMF)2(NO3)2] (2) (H2L = 2-(2-hydroxy-3-methoxybenzylideneamino)phenol), is introduced and investigated. Through modifying the ligands on the changeable coordination sites, the intramolecular magnetic interactions and relaxation dynamics in these two Dy(iii)4 SMMs can be tuned. Both complexes exhibit slow relaxation of their magnetization with a relaxation barrier of 114 K for complex 2 while a blocking temperature below 2 K is observed for complex 1. Ab initio calculations reveal that changes in coordination numbers and geometries on the Dy(iii) sites can significantly affect the magnetic interactions as well as single-ion anisotropy. The combination of experimental work and ab initio calculations offers insight into the relationship between structures and magnetic properties and sheds light on the rational design of future polynuclear lanthanide SMMs with enhanced magnetic properties. [ABSTRACT FROM AUTHOR]

Two isostructural lanthanide-based MOFs [Ln(HL)L]·H2O (1-Ln, Ln = Eu, Dy, H2L = 5-((pyridin-4-ylthio)methyl)isophthalic acid) were successfully obtained via the solvothermal reaction. 1-Eu exhibits high fluorescence quenching efficiency for C2O72− and Fe3+, which can be potentially used as a luminescent probe; 1-Dy behaves as a typical single-molecule magnet with an energy barrier (ΔUeff) of 54(2) K. [ABSTRACT FROM AUTHOR]

A new luminescent metal–organic framework, {[Cd3(HL)2(H2O)3]·3H2O·2CH3CN}n (1) (H4L = 1-(3,5-dicarboxylatobenzyl)-3,5-pyrazole dicarboxylic acid), has been synthesized by solvothermal reaction and characterized by infrared spectroscopy, powder X-ray diffraction, thermogravimetry measurements and so on. 1 shows a new trinodal (4,4,6)-connected topology. Importantly, 1 displays intense luminescence in the solid state and high luminescent sensitivity and selectivity for Fe3+, CrO42− and Cr2O72− ions in aqueous solution, making it a potential probe for detecting these substances. The quenching mechanisms are also further discussed in detail. In addition, further research on the adsorption of dyes shows that 1 can selectively adsorb Congo red dye from other dye molecules. [ABSTRACT FROM AUTHOR]

A new Zn(ii) metal–organic framework (MOF) [Me2NH2][Zn2(BDPP)(HTZ)]·4DMF (1) (H4BDPP = 3,5-bis(3,5-dicarboxylphenyl)pyridine, HTZ = 1H-tetrazole) has been constructed under solvothermal conditions by using a mixed-ligand strategy. Structural analysis demonstrates that 1 is a 3D framework based on four kinds of secondary building units (SBUs), which presents a rare structure constructed from quaternary SBUs and shows an uncommon (3,3,4,6)-connected topology. In particular, 1 contains two shapes of 1D open channels with suitable pore sizes, high porosity, and a highly polar pore system decorated with uncoordinated N atoms and carboxylic O atoms, providing a good environment for selective adsorption of CO2. Inspired by the structure of 1 and reticular chemistry, 5-amino-1H-tetrazole (ATZ) was used to replace 1H-tetrazole to enhance CO2 sorption capacity by pore surface modification; as a result, an amino-functionalized MOF, [Me2NH2][Zn2(BDPP)(ATZ)]·4DMF (1-NH2) was successfully built. 1-NH2 exhibits multipoint interactions between the CO2 molecules and the framework, resulting in better CO2 uptake and selectivity for CO2 over CH4 than 1. [ABSTRACT FROM AUTHOR]

Four new metal–organic frameworks (MOFs), {[Zn3(L)(OH)(H2O)5]·NMP·2H2O}n (1), {[H2N(Me)2][Zn2(L)(H2O)]·DMF·H2O}n (2), {[Co5(L)2(H2O)11]·2H2O}n (3) and {[Mn5(L)2(H2O)12]·6H2O}n (4), were assembled employing a symmetrical V-shaped rigid multicarboxylic acid ligand H5L (H5L = 2,4-di(3′,5′-dicarboxylphenyl)benzoic acid) with different metal ions, resulting in versatile frameworks as well as various types of coordination modes of H5L. 1 forms a three-dimensional (3D) 4-connected sra net based on trinuclear [Zn3(μ3-OH)(μ2-COO)(μ1-COO)4] clusters, while 2 displays a 3D (4,6)-connected net based on two types of binuclear [Zn2(μ2-COO)2(μ1-COO)4] and [Zn2(μ2-COO)4] clusters. 3 and 4 contain similar [M3(μ2-COO)4(μ1-COO)2] (3, M = Co; 4, M = Mn) clusters but result in different 4-connected 3D and 2D frameworks, respectively. 1 and 2 show solid-state luminescence properties at ambient temperature. Meanwhile, 1 shows high selectivity and sensitivity for not only Fe3+ cations but also for CrO42−, Cr2O72− and MnO4− anions via a luminescence quenching effect with a low detection limit, which thus means that it could be a potential crystalline material for detecting these anions. The mechanisms of the quenching effect and sensing properties of 1 are discussed in detail. In addition, 3 and 4 have the presence of antiferromagnetic interactions between the metal ions. [ABSTRACT FROM AUTHOR]

Two new three-dimensional (3D) porous metal–organic frameworks (MOFs), {[Cd2(L)(NMP)(H2O)2]·2H2O}n (1) and {[Zn(L)0.5(H2O)]·NMP·H2O}n (2), have been solvothermally synthesized by using Zn(ii) and Cd(ii) ions with H4L (H4L = 1,4-di(5,6-bicarboxylbenzimidazol-lylmethyl)benzene) in different ratios of H2O and NMP (NMP = 1-methyl-2-pyrrolidinone) solvents, all of which have been characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). As revealed by structural analysis, the H4L ligand took different coordination fashions in 1 and 2, and as a result, two MOFs with a novel (3,4,7)-connected trinodal net and (3,6)-connected binodal net were obtained, respectively. The structure comparison reveals that the coordination modes of ligands and the types of metal ions play decisive roles in regulating the final networks of MOFs. The desolvated frameworks 1 and 2 possess polar channels decorated with uncoordinated carboxylate groups, leading to an excellent ability to attract CO2 as well as significant adsorption selectivity for CO2 over CH4 at 273 and 298 K. Solid state 1 and 2 show blue photoluminescence. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

Six new complexes based on 5-(triazol-1-yl)nicotinic acid (HL), namely [Cu2(L)3(H2O)(OH)]n (1), [Co(L)2(H2O)2]n (2), [Mn(L)2(H2O)2]n (3), {[Co(L)(H2O)0.5(DMF)0.5(NO3)0.5]·(Cl)0.5·DMF·2H2O}n (4), {[Cu(L)(O)0.5]·CH3OH·2.5H2O}n (5) and {[Co2(L)4(H2O)]·2DMA·2H2O}n (6), were synthesized under hydro(solvo)thermal conditions. The L− ligand in 1–6 reveals various coordination modes and forms diverse secondary building units (SBUs) in the final structures. Complex 1 shows a 2D layered structure with a rare (3,8)-connected topology based on tetranuclear [Cu4(COO)6(H2O)2(OH)2N6] SBUs. 2 and 3 are isostructural and display 2D 4-connected sql nets with a point symbol of (44·62). 4 and 5 have similar spatial 3D porous frameworks, which can be simplified as a (3,6)-connected 2-nodal net via dinuclear [Co2(COO)2(O)2(NO3)(N)4] SBUs and [Cu2(COO)2(O)(N)4] SBUs, respectively. 6 is a 3D porous framework constructed by dinuclear [Co2(COO)4(H2O)(N)4] motifs with a uninodal 4-connected qtz net. The magnetic properties and gas sorption behaviour of these complexes were investigated carefully, showing that 3 exhibits ferrimagnetic character and 4 demonstrates its effective storage capacity for CO2 as well as high selectivity for CO2 over CH4 under ambient conditions. [ABSTRACT FROM AUTHOR]

Under ambient conditions, CO2 was captured from atmosphere and reduced for sequestering CO2 into two {Dy2} single-molecule magnets through an in situ organic ligand reaction of hydrazine. A reasonable reaction mechanism is proposed, which provides a promising route towards the capturing and transforming CO2 into single-molecule magnets. [ABSTRACT FROM AUTHOR]

Herein we explored the transitions of two magnetic interaction states (antiferromagnetic or ferromagnetic) upon structural variations in two dinuclear Dy(iii) complexes. [ABSTRACT FROM AUTHOR]

In search of simple approaches to rationally enhance the energy barriers in polynuclear dysprosium single-molecule magnets, a new system containing two structurally closely related dinuclear dysprosium complexes, namely [Dy2(L)2(DBM)2(DMF)2] (1) and [Dy2(L)2(DBM)2(DMA)2]·2DMA (2) (HDBM = dibenzoylmethane, H2L = 2-hydroxy-N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide), is introduced and the structure-dependent magnetic properties are investigated. The two complexes display only slight variations in the coordination geometries of the Dy(iii) ion but display remarkably different magnetic behaviors. By replacing the DMF (dimethylformamide) ligand in complex 1 with DMA (dimethylacetamide) in 2 while retaining the same coordination atoms, we were able to create a 3-fold enhancement in the energy barrier, from 24 K for complex 1 to 77 K for complex 2. Complete-active-space self-consistent field (CASSCF) calculations revealed that the charge distribution surrounding the Dy(iii) centers in 1 and 2 is the key factor in determining the relaxation properties of the SMMs. The introduction of an electron-donating CH3 group in DMA to replace the hydrogen in DMF resulted in a larger average charge along the magnetic axes of complex 2 compared to complex 1, which resulted in a stronger easy-axis ligand field, thus increasing the energy difference between the ground and the first excited states of complex 2. This work presents a simple method to rationally enhance the energy barrier in polynuclear lanthanide SMMs through fine-tuning of the electrostatic potential of the atoms along the magnetic axis. [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]

Based on Cd(NO3)2·4H2O and 4,4′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), two isomeric coordination polymers, {[Cd1.5(cpbda)(bpa)(H2O)2]·1.5H2O}n (1), [Cd(H2cpbda)2(bpa)0.5(H2O)]n (2), were synthesized by using different solvent-systems. The complexes were characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. Owing to the obvious structural difference between the two isomeric complexes, the further fluorescence sensing and dye selection and adsorption were investigated. The 3D tight stacking structure of 1 strengthened the fluorescence emission and the loose 2D layer structure of 2 generated the active selection and adsorption of the Malachite Green Oxalate (MGO) dye. [ABSTRACT FROM AUTHOR]

Four new isostructural lanthanide–organic frameworks, [Ln(L)(H2O)2]·H2O·CH3CN (1-Ln) (Ln = Eu, Tb, Dy, and Gd), have been successfully synthesized via solvothermal reactions with a semi-rigid V-shaped multicarboxylate ligand 2-(2′,4′-dicarboxylphenoxy) benzoic acid (H3L) and Ln(NO3)3·6H2O. 1-Ln shows 2D layer-by-layer frameworks with interlayer channels decorated by carboxylate groups. 1-Eu exhibits excellent luminescence properties, and therefore, is chosen as a probe for sensing different metal ions and anions. Consequently, 1-Eu displays high selectivity and sensitivity for Fe3+ and Cr6+ ions, simultaneously, through the luminescence quenching effect, and thus, should be an excellent candidate for probing these pollutant metal ions. In addition, antiferromagnetic exchange interactions also exist between the Dy3+ ions in 1-Dy. [ABSTRACT FROM AUTHOR]

Two novel porous luminescent metal–organic frameworks (MOFs, 1 and 2) have been constructed using 3,4-di(3,5-dicarboxyphenyl)phthalic acid using a hydrothermal method. Both MOFs can work as highly sensitive sensors to Fe3+ by luminescent quenching. Analyses of the structures indicate a higher quenching efficiency of 2 because of the existence of active –COOH groups. Based on this consideration, the quenching mechanisms are studied and the processes are controlled by multiple mechanisms in which dynamic and static mechanisms of MOFs are discussed. Besides, the corresponding dynamic and static quenching constants are calculated, achieving the quantification evaluation of the quenching process. As expected, experimental data show that compound 2 possesses an overall quenching efficiency 6.9 times that of compound 1. Additionally, time-dependent intensity measurements, the shifts of the excitation spectrum and the appearance of a new emission peak all give visual proofs of the distinct mechanisms between the two MOFs. [ABSTRACT FROM AUTHOR]

Six new Co(ii)-based mixed-ligand coordination polymers, namely, [Co2(H3bppc)2(2,2′-bpy)4]·H2O (1), [Co2(Hbppc)(2,2′-bpy)2(H2O)]·H2O (2), [Co(H2bppc)(H-bpp)]·2H2O (3), [Co3(μ3-OH)(bppc)(dps)(CH3CH2OH)]·4H2O (4), [Co2(bppc)(bib)(H2O)4]·(H2-bib)0.5·(H2O)3 (5), and [Co2(Hbppc)(bix)2]·2H2O (6), (H5bppc = biphenyl-2,4,6,3′,5′-pentacarboxylic acid, 2,2′-bpy = 2,2′-bipyridine, bpp = 1,3-bis(4-pyridyl)propane, dps = 4,4′-sulfanediyldipyridine, bib = 1,4-bis(imidazol-1-yl)benzene, bix = 1,4-bis(imidazol-1-ylmethyl)benzene), have been obtained under solvothermal conditions. 1 exhibits a 3D supramolecular framework based on a [Co2(H3bppc)2(2,2′-bpy)4] unit. 2 has a (3,4)-connected dmc net with a (4·82)(4·85) topology containing alternate binuclear metal clusters and single metal centres. 3 shows a 3D supramolecular architecture constructed from ladder-like arrays decorated with H-bpp. 4 exhibits a binodal (5,7)-connected 3D network based on trinuclear [Co3(μ3-OH)]5+ units with an unusual (3·46·52·6)(32·46·57·65·7) topology. 5 features a (4,6)-connected 3D fsc open framework with binuclear [Co2(H2O)(COO)]3+ units as nodes, and H2-bib and water molecules located in the voids of its framework by hydrogen bonds. 6 possesses a 3D net containing unusual 2D polyrotaxane sheets. Topological analysis reveals that 6 has a (3,4,4)-connected 3D network with a (4·6·74)(4·6·7)(6·72·102·11) topology. The structural difference of 1 and 2 is due to the different pH values of the reaction system. Though complexes 2–6 were synthesised under similar reaction conditions, the carboxylic groups of H5bppc were partially deprotonated in 2, 3 and 6 and fully deprotonated in 4 and 5. Complexes 2–6 display diverse structures depending on different N-donor ligands and the coordination modes of the multicarboxylate ligand. Variable-temperature magnetic susceptibility measurements reveal that complexes 1–6 show antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

Four super water-stable isostructural lanthanide–organic frameworks, [Ln(HL)(H2O)2]n·2H2O (1-Ln) (Ln = Eu, Tb, Nd and Sm), have been successfully synthesized under hydrothermal conditions with 3,5-di(2,4-dicarboxylphenyl)pyridine (H4L) and Ln(NO3)3·6H2O. 1-Ln shows a novel 2D layered structure with uncoordinated carboxylic and pyridyl groups pointing to the interior of interlayer channels. The luminescent properties of 1-Eu in the solid state and one steeped in aqueous solution have been measured, which show excellent luminescence and good luminescent stability in water. Next 1-Eu was chosen as a probe for sensing different metal ions. Consequently, 1-Eu exhibits a highly selective response to Fe3+ through the luminescence quenching effect in aqueous solutions. The probable mechanisms of the quenching effects have been investigated in detail. [ABSTRACT FROM AUTHOR]

Three new Cd(ii)-MOFs, [Cd(L1)0.5(bpp)] (1), [Cd(L1)0.5(bipy)] (2), and [Cd(L2)0.5(bipy)] (3) [H4Ln = (1,1′:4′,1′′-terphenyl)-2′,x,x′′,5′-tetracarboxylic acid (n = 1, x = 3, and n = 2, x = 4), bpp = 1,3-di(4-pyridyl)propane, and bipy = 2,2′-bipyridine], have been synthesized using Cd(ii) ions and isomeric H4Ln ligands in the presence of auxiliary ligands via solvothermal reaction, and have been fully characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Complex 1 is a three-dimensional (3D) pillar-layered network built from L14− and bridging bpp co-ligands with a binodal (4,8)-connected gsp2 topology and a symbol of (44·62)(416·612). 2 was successfully synthesized using bipy instead of the bpp ligand used to assemble 1 giving a 2D 4-connected sql net. 3 is a 3D reticular framework with [Cd2(COO)4] SBUs based on L24− ligands, displaying a (4,4)-connected lvt (42·84) topology. X-ray diffraction analysis revealed that the structures of the MOFs can be mediated by the steric effect of the tetracarboxylate and secondary co-ligands. The solid-state luminescence properties of the MOFs were measured carefully by ultraviolet irradiation at room temperature. In particular, 3 exhibited a high sensitivity for Fe3+ in aqueous solutions of mixed metal ions, which makes it a promising crystalline material to be a luminescent probe for Fe3+. Importantly, 3 can keep its original framework and be reused in sensing experiments. The sensing mechanism has also been studied in detail. [ABSTRACT FROM AUTHOR]

A new 2D highly flexible and breathing porous framework [CuL(Me2NH)]·DMF·H2O (1) (H3L = 5-(4′-carboxylphenoxy)nicotinic acid) has been synthesized using a tritopic linker with a flexible joint. The desolvated framework, [CuL(Me2NH)] (1a), undergoes structural contraction, and exhibits selective and double-step hysteretic adsorption for CO2. Furthermore, on exposure to CH2Cl2 at room temperature, a unique single-crystal-to-single-crystal transformation occurred between 1 and [Cu2L2(Me2NH)2(H2O)2]·5H2O (1b). [ABSTRACT FROM AUTHOR]

Three new solvent-induced metal–organic frameworks (MOFs)―[Cd(H2L)(H2O)3]·NMP (1), [Cd3(L)(H2O)4(OH)2] (2) and [Cd(L)0.5(H2O)]·H2O (3)―were designed and successfully prepared via solvothermal reaction by multidentate phenyltetracarboxylic acid [1,1′:4′,1′′-terphenyl]-2′,3,3′′,5′-tetracarboxylic acid (H4L) and Cd(ii) salts in various solvent systems. Structural analyses indicated that the H2L/L ligands took three different coordination fashions in 1–3, and thus resulted in diversity of the targeted MOFs. Solid-state luminescent properties of the three MOFs were studied under ultraviolet light irradiation at ambient temperature; 3 in particular showed high selectivity and sensitivity for Cu2+ ions and nitrobenzene because of the quenching effect, which thus could make it a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 3 are discussed in detail. [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]

Two new Co(II) based metal-organic frameworks, namely {[Co5(μ3-OH)2(m-pda)3(bix)4]·2ClO4}n (1) and {[Co2(p-pda)2(bix)2(H2O)]·H2O}n (2), were prepared by hydrothermal reactions of Co(II) salt with two isomeric dicarboxyl tectons 1,3-phenylenediacetic acid (m-pda) and 1,4-phenylenediacetic acid (p-pda), along with 1,3-bis(imidazol-L-ylmethyl)benzene (bix). Both complexes 1 and 2 have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). 1 shows a 6-connected 3-D pcu cationic framework with pentanuclear [Co5(μ3-OH)2(COO)6(bix)2]2+ units, while 2 exhibits a 6-connected 3-D msw net based on [Co2(μ2-H2O)(COO)2]2+ clusters. The results indicate that the different dispositions of the carboxylic groups of dicarboxylates have an important effect on the overall coordination frameworks. Perchlorate anions in 1 can be partly exchanged by thiocyanate and azide anions, however they are unavailable to nitrate anions. Magnetic susceptibility measurements indicate that both 1 and 2 show weak antiferromagnetic interactions between the adjacent Co(II) ions. [ABSTRACT FROM AUTHOR]

Four new coordination polymers (CPs), [Co3(L)2(bib)3(EtOH)2]·2H2O (1), [Mn3(L)2(bib)2(H2O)4]·4H2O (2), [Ni(HL)(bib)(H2O)3] (3) and [Ni3(bib)4(H2O)10]·2(L)·12(H2O) (4), were synthesized under solvothermal conditions with an unsymmetrical tricarboxylic acid ligand [biphenyl-3,3',5-tricarboxylic acid (H3L)] in the presence of the 1,4-bis(1H-imidazol-4-yl)benzene (bib) ligand. In compound 1, tricarboxylate acid ligands (H3L) link Co centers to generate two-dimensional (2D) layers which are further connected by bib ligands to exhibit a three-dimensional (3D) framework with a (4,4,5)-connected (4²·6³·8)2(4²·67·8)2(64·8·10) topology. The three-dimensional (3D) framework of 2 is defined as a (3,3,4)-connected topology with the point symbol of (6·8²)2(6²·8)2(8·104·12). Compound 3 contains a one-dimensional (1D) left-hand helix chain along the a direction and further extends into a 2D supramolecular network and a 3D supramolecular framework via hydrogen bonds. Compound 4 displays a one-dimensional (1D) molecular ladder, which is further combined with each other through π...π stacking to extend into 2D supramolecular sheets. The supramolecular networks of 3 and 4 resulted from the different solvent ratios [V(H2O)-V(EtOH)] in the reaction. All the CPs are characterized by single-crystal X-ray diffraction analyses, powder X-ray diffraction (PXRD), elemental analyses, IR spectroscopy, and TGA analyses. Moreover, the weak ferromagnetic properties of 2 and 3 and antiferromagnetic properties of 1 and 4 have also been investigated. [ABSTRACT FROM AUTHOR]

By reacting an asymmetry semi-rigid Y-shaped/L-shaped linker H3cpta (H3cpta = 3-(4'-carboxyphenoxy)- phthalic acid) and Co(CH3COO)3'6H2O under different N-donor ligands in different solvents, three new Co-based coordination polymers, [Co3(cpta)2(bpe)3(H2O)4] (1) [Co(μ2-H2O)(μ3-OH)(Hcpta)(bpe)(H2O)' 3(DMF)3(H2O)] (2) and [Co3(cpta)2(bpa)4] (3) have been obtained. They exhibit trinodal topological nets/ layer, based on Co2+ ions and Y-shaped/L-shaped carboxylate linkers. 1 and 3 present 3D frameworks with the point symbol {4·102}2{105·12}{4·85}2 for 1 and {4·82}3{85·9}{4·67·92}3 for 3. While, 2 exhibits a 2D layer with the point symbol {4·6·8}{4·62·83}{62·8}. The magnetic studies indicate that all of the three complexes show antiferromagnetic exchanges transmitted through μ3-carboxylate/μ4-carboxylate bridges, μ2- H2O molecules and μ3-OH ions between Co2+ ions, respectively. And the result of this research shows that the solvent and the secondary ligands could co-regulate coordination polymer with interesting properties, providing a constructive guidance when synthesizing versatile topologies with the same organic spacer but a different architecture. [ABSTRACT FROM AUTHOR]

Necklace-like MgO/TiO2 heterojunction structures were synthesized by a simple and economical precursor calcination method for the first time. The obtained unique MgO/TiO2 heterojunction structures exhibit an excellent removal performance towards toxic As(V) ions combined with good photocatalytic properties towards organic dyes. [ABSTRACT FROM AUTHOR]

Three new solvent-directed three-dimensional (3D) lead(ii) coordination polymers, [Pb2(L)2]n (1), [Pb3(L)3]n (2) and [Pb(L)]·H2O (3) [H3L = 2-(pyridine-2-yl)-1H-imidazole-4,5-dicarboxylic acid], have been synthesized solvothermally. As influenced by different solvent systems, compounds 1 and 3 exhibit varying architectures from a multi-nodal 3,3,4,4-connected to a uninodal 3-connected net, while 2 with helices represents a binodal 3,4-connected topological net. Moreover, 3 possesses a micropore which is decorated with pyridyl systems and uncoordinated carboxylate oxygen atoms. In addition, the small-sized and highly polar pores enable 3 to attract CO2 strongly, leading to a high sorption heat for CO2 and significant selectivity for CO2 over H2 and N2 at 293 K. The luminescent behaviors and emissive lifetimes of 1–3 are also discussed. [ABSTRACT FROM AUTHOR]

An acylamide-functionalized 3D microporous metal–organic framework built on Zn2 clusters with mixed H3bcta and dipy ligands, which shows unprecedented 2D → 3D polycatenation based on dipy-pillared honeycomb bilayers, and exhibits highly selective CO2 capture. [ABSTRACT FROM AUTHOR]

Along with our recent investigation on the flexible ligand of H2ADA (1,3-adamantanediacetic acid), a series of ZnIIand CdIImetal–organic frameworks, namely, [Zn3(ADA)3(H2O)2]n·5nH2O (1), [Zn(ADA)(4,4′-bipy)0.5]n(2), [Zn2(ADA)2(bpa)]n(3), [Zn2(ADA)2(bpa)]n(4), [Zn2(ADA)2(bpp)]n(5), [Cd(HADA)2((4,4′-bipy)]n(6), [Cd3(ADA)3(bpa)2(CH3OH)(H2O)]n(7), and [Cd2(ADA)2(bpp)2]n·7nH2O (8) have been synthesized and structurally characterized (where 4,4′-bipy = 4,4′-dipyridine, bpa = 1,2-bis(4-pyridyl)ethane and bpp = 1,3-bis(4-pyridyl)propane). Due to various coordination modes and conformations of the flexible dicarboxylate ligand and the different pyridyl-containing coligands, these complexes exhibit structural and dimensional diversity. Complex 1exhibits a three-dimensional (3D) framework containing one-dimensional (1D) ZnII–O–C–O–ZnIIclusters. Complex 2exhibits a 2D structure constructed by 1D double chains based on [Zn2ADA2] units and a 4,4′-bipy pillar. Complexes 3and 4possess isomorphic 2D layer structures, resulting from the different coordination modes of carboxylate group of ADA ligands. Complex 5features a 2D 44layer in which ADA ligands and ZnIIatoms construct a 1D looped chain and the chains are further connected by bpp ligands. Complex 6is composed of 1D zig-zag chains that are entangled through hydrogen-bonding interactions to generate a 2D network. Complex 7is a rare (3,5)-connected network. Complex 8possesses a 3D microporous framework with lots of water molecules encapsulated in the channels. The structural diversity of the complexes perhaps mainly results from using diverse secondary ligands and different metal centre ions, and means the assistant ligand and metal centre play important roles in the design and synthesis of target metal–organic frameworks. This finding revealed that ADA could be used as an effective bridging ligand to construct MOFs and change coordination modes and conformational geometries in these complexes. The thermogravimetric analyses, X-ray powder diffraction and solid-state luminescent properties of the complexes have also been investigated. [ABSTRACT FROM AUTHOR]

Six new coordination polymers, namely {[Zn(btec)0.5(btmb)]·2H2O}n(1), {[Co(btec)0.5(btmb)(H2O)]·3H2O}n(2), {[Cu(btec)0.5(btmb)]·H2O}n(3), {[Cu4(btc)4(btmb)4]·H2O}n(4), {[Co3(bta)2(btmb)2]·2H2O}n(5), [Co(Hbta)(btmb)]n(6) (H4btec = 1,2,4,5-benzenetetracarboxylate, H3btc = 1,3,5-benzenetricarboxylate, H3bta = 1,2,4-benzenetricarboxylate and btmb = 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl), have been successfully synthesized under hydrothermal conditions. All these complexes were structurally determined by single-crystal X-ray diffraction, elemental analysis, IR, TGA and XRD. Crystal structural analysis reveals that 1is the first example of an unusual 3D framework with (86) topology containing a 2D molecular fabric structure. Complex 2exhibits a 3D NbO network with (64·82) topology. In 3, Cu(ii) ions are coordinated by anti-conformational btmb ligands to form left- and right-handed double helices, which are further bridged by the 4-connected btec4−anions to give a 3D porous network. Complex 4presents a rare 3D gra network structure with (63)(69·8) topology. 5and 6were obtained through controllable pH values of solution, 5features a scarce binodal (3,8)-connected tfz-d framework with the trinuclear Co(ii) clusters acting as nodes, whereas 6has an extended 2D 44grid-like layer and the adjacent 2D layers are interconnected by strong hydrogen bonding interactions into a 3D supramolecular framework. The structural diversities indicate that distinct organic acid ligands, the nature of metal ions and the pH value play crucial roles in modulating the formation of the resulting coordination complexes and the connectivity of the ultimate topological nets. Moreover, magnetic susceptibility measurement of 5indicates the presence of weak ferromagnetic interactions between the Co(ii) ions bridged by carboxylate groups. [ABSTRACT FROM AUTHOR]

Two unique six-connected self-penetrating coordination polymers with a new (44.610.8) network topology, derived from the cross-linking of two 66-diasubnets, were constructed from NiIIor CoIIand two types of V-shaped tectons. The NiIIcomplex 1shows an antiferromagnetic coupling viaμ-carboxylate and μ-H2O pathways, whereas the CoIIcomplex 2exhibits the single-ion behavior in 300–34 K and then a ferromagnetic coupling at lower temperatures. [ABSTRACT FROM AUTHOR]

This article represents a systematical investigation on the structures of silver(i) dicarboxylate incorporating secondary ligands, revealing that the secondary interactions could play an important role in interlinking low-dimensional entities to high-dimensional supramolecular frameworks. A new 2D silver(i) crystalline dicarboxylate, {[Ag6(ADC)3(H2O)1.5]2·5.18H2O}n(1) (H2ADC = 1,3-adamantanedicarboxylic acid), has been obtained by slow diffusion of corresponding precursors. To investigate the influence of the properties of pyridylic neutral ligands on the complex structures based on compound 1, five kinds of neutral ligands (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; bpdap = N,N′-bis(3-pyridyl)-2,6-diaminopyridine) were selected, and a series of new silver(i) dicarboxylate have been synthesized: {[Ag(bpa)(HADC)]}n(2), {[Ag(bpp)(HADC)]·CH3OH}n(3), {[Ag4(bpe)3(ADC)2]·2H2O}n(4), {[Ag(bipy)(HADC)]·H2O}n(5), {[Ag2(bipy)2(ADC)]·6H2O}n(6), and [Ag8(bpdap)4(ADC)4]·2C2H5OH·6H2O (7). Single-crystal X-ray structural analysis shows that complexes 1and 4are formed by hexanuclear and tetranuclear Ag(i) clusters with weak Ag–Ag interactions. Complexes 2and 3are dinuclear structures, 5and 6exhibit an infinite 1D chain structure, whereas 7is a discrete octanuclear Ag(i) unit. The structures of 1–7span from dinuclear, tetranuclear, hexanuclear, to octanuclear Ag(i) complexes, which indicates that secondary ligands do play important roles in the formation of such coordination architectures. Thermal stability, X-ray powder diffraction and luminescent properties of the compounds are also discussed. [ABSTRACT FROM AUTHOR]

A series of new metal–organic coordination complexes, {[Ni(IP)(H2O)4]·(2H2O)(SO4)} (1), [M(IP)(μ2-SO4)(H2O)2] (M = Zn 2, and M = Mn 3), {[M2(IP)2(μ2-SO4)2(H2O)4]·2H2O} (M = Zn 4, and M = Co 5), {[Mn2(IP)(μ2-SO4)(H2O)2]·(6.5H2O)(sdba)} (6), {[Mn(IP)2(H2O)2][Mn(pydc)2(H2O)2]·(4H2O)} (7), {[Mn(IP)(fum)(H2O)]·H2O} (8), {[M3(IP)3(fum)3]·(8H2O)} (M = Cd 9, and M = Zn 10), {[Cd2(IP)2(bptc)(H2O)2]·(7.3H2O)} (11), {[Zn2(IP)2(bptc)(H2O)2]·(3H2O)} (12), {Cd(1,4-BDC)(IP)(H2O)]·(0.5H2O)} (13), {[Mn(1,4-BDC)(IP)(H2O)]·H2O} (14), {[Zn2(1,4-BDC)2(IP)]·2.5H2O} (15) (IP = 1H-imidazo[4,5-f][1,10]-phenanthroline, H2sdba = 4,4′-sulfonyldibenzoic acid, H2pydc = pyridine-2,6-dicarboxylic acid, H2fum = fumaric acid, H4bptc = 3,3′,4,4′-benzophenonetetracarboxylic acid and 1,4-H2BDC = 1,4-benzendicarboxylic acid) were prepared viaself-assembly of pharmaceutical agent IP with different metal sulfates in the absence/presence of the carboxylate under mild conditions. All these compounds were structurally determined by single-crystal X-ray diffraction. Compounds 2–6crystallize with N-donor chelating ligands and sulfate anion linkers. Complexes 2–6possess sulfate anions with μ2-bridging modes, the roles of sulfate anions result in 1D chains (2and 3) and dinuclear units (4, 5and 6). For complex 7, two different Mn units are chelated by two IP and pydc ligands, respectively. Compound 8is a 1D chain connected by fum ligands. Polymers 9–12exhibit 2D network structures composed of tetrametallic and hexametallic clusters. The Cd(ii)/Zn(ii) layers are interdigitated in pairs for complexes 11and 12by stacking forces, which exhibit unusual 2D→3D interdigitated architectures. In 13and 14, they show 1D undulating and linear chains due to the different coordinate modes of 1,4-BDC. IP firstly acts in a tridentate mode viathe two N atoms of pyridyl rings and the third N atom of imidazole ring, and the two carboxylate groups of 1,4-BDC ligand taking three types of coordinative modes connect Zn atoms into a complicated 3D network in 15. The structural differences among complexes 1–15indicate the backbone of such dicarboxylate ligands, nature of metal resources and the ratio of metal to ligand play important roles in modulating the formation of the coordination polymers. Thermal stabilities of these crystalline materials, fluorescent properties of these complexes and TD-DFT calculation of spectra of IP were also investigated. [ABSTRACT FROM AUTHOR]

Two novel porous luminescent metal–organic frameworks (MOFs, 1 and 2) have been constructed using 3,4-di(3,5-dicarboxyphenyl)phthalic acid using a hydrothermal method. Both MOFs can work as highly sensitive sensors to Fe3+ by luminescent quenching. Analyses of the structures indicate a higher quenching efficiency of 2 because of the existence of active –COOH groups. Based on this consideration, the quenching mechanisms are studied and the processes are controlled by multiple mechanisms in which dynamic and static mechanisms of MOFs are discussed. Besides, the corresponding dynamic and static quenching constants are calculated, achieving the quantification evaluation of the quenching process. As expected, experimental data show that compound 2 possesses an overall quenching efficiency 6.9 times that of compound 1. Additionally, time-dependent intensity measurements, the shifts of the excitation spectrum and the appearance of a new emission peak all give visual proofs of the distinct mechanisms between the two MOFs. [ABSTRACT FROM AUTHOR]

Four super water-stable isostructural lanthanide–organic frameworks, [Ln(HL)(H2O)2]n·2H2O (1-Ln) (Ln = Eu, Tb, Nd and Sm), have been successfully synthesized under hydrothermal conditions with 3,5-di(2,4-dicarboxylphenyl)pyridine (H4L) and Ln(NO3)3·6H2O. 1-Ln shows a novel 2D layered structure with uncoordinated carboxylic and pyridyl groups pointing to the interior of interlayer channels. The luminescent properties of 1-Eu in the solid state and one steeped in aqueous solution have been measured, which show excellent luminescence and good luminescent stability in water. Next 1-Eu was chosen as a probe for sensing different metal ions. Consequently, 1-Eu exhibits a highly selective response to Fe3+ through the luminescence quenching effect in aqueous solutions. The probable mechanisms of the quenching effects have been investigated in detail. [ABSTRACT FROM AUTHOR]