In Situ Exfoliation Growth Strategy Realizing Controlled Synthesis of 3D to 2D MOF Materials as High-Performance Electrochemical Biosensors.

Two-dimensional (2D) metal-organic framework (MOF) nanosheets with large surface area, ultrathin thickness, and highly accessible active sites have attracted great research attention. Developing efficient approaches to realize the controllable synthesis of well-defined 2D MOFs with a specific composition and morphology is critical. However, it is still a significant challenge to construct thin and uniform 2D MOF nanosheets and resolve the reagglomeration as well as poor stability of target 2D MOF products. Here, an "in situ exfoliation growth" strategy is proposed, where a one-step synthetic process can realize the successful fabrication of PBA/MIL-53(NiFe)/NF nanosheets on the surface of nickel foam (NF) via in situ conversion and exfoliation growth strategies. The PBA/MIL-53(NiFe)/NF nanosheets combine the individual advantages of MOFs, Prussian blue analogues (PBAs), and 2D materials. As expected, the resulting PBA/MIL-53(NiFe)/NF as a glucose electrode exhibits an extremely high sensitivity of 25.74 mA mM-1 cm-2 in a very wide concentration range of 180 nM to 4.8 µM. The present exciting work provides a simple and effective strategy for the construction of high-performance nonenzymatic glucose electrochemical biosensors.

UiO-66-Derived PBA Composite as Multifunctional Electrochemical Non-Enzymatic Sensor Realizing High-Performance Detection of Hydrogen Peroxide and Glucose.

In this work, a highly efficient multifunctional non-enzymatic electrochemical sensor is successfully fabricated based on a facile two-step synthetic strategy. It resolves two important challenges of poor stability and low reproducibility compared to conventional electrochemical enzyme-based sensors. Herein, a metal-organic framework (UiO-66) is selected as a sacrificial template to construct the corresponding Prussian blue analogue (PBA) target to improve its stability and conductivity, namely, PBA/UiO-66/NF. Target PBA/UiO-66/NF exhibits excellent electrochemical sensing performance as hydrogen peroxide (H2O2) and glucose sensors with ultrahigh sensitivity of up to 1903 µA mM-1 cm-2 for H2O2 and 22,800 µA mM-1 cm-2 for glucose, as well as a very low detection limit of 0.02 µM (S/N = 3) for H2O2 and 0.28 µM for glucose. Especially, extremely high stability can be observed, which will be beneficial for practical application.

Indium-Based Metal-Organic Framework for Efficient Photocatalytic Hydrogen Evolution.

In this work, an indium-based metal-organic framework was successfully constructed, namely, as In-MOF, by elaborately selecting an InIII center with unique properties and a functional tetracarboxylic acid with unsaturated and open-coordinated nodes. Interestingly, the InIII center was connected to a single-metal-node-based porous three-dimensional pts net. Its structure was dentified by single-crystal and powder X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, etc. Considering the special luminescent characteristic of an indium-based framework, as-prepared In-MOF was explored as a photocatalyst for H2 production from water splitting. The testing results demonstrate that In-MOF as a promising photocatalyst with a suitable band gap realizes a H2 evolution efficiency of 777.65 µmol g-1 h-1.

Molecular Regulation Based on Functional Trimetallic Metal-Organic Frameworks for Efficient Oxygen Evolution Reaction.

Metal-organic frameworks (MOFs) as classic crystalline porous materials have attracted great interest in the catalytic field. However, how to realize molecular regulation of the MOF structure to achieve a remarkable oxygen evolution reaction (OER) electrocatalyst is still a challenge. Herein, we designed several series of special MOF materials to explore the relationship between the structure and properties as well as the related reactive mechanism. First, various metal centers, including Fe, Co, Ni, Zn, and Mg, were utilized to construct the first series of trimetallic MOF materials, namely, M3-MOF-BDC, where BDC = 1,4-benzenedicarboxylic acid, also known as terephthalic acid. Among of them, Fe3-MOF-BDC shows the best OER performance and only needs an overpotential of 312 mV at 10 mA cm-2. Then, functional BDC-X ligands (X = NH2, OH, NO2, DH) with various characteristic groups were selected to construct a new series, namely, Fe3-MOF-BDC-X, to further improve its OER electrocatalytic performance. As expected, Fe3-MOF-BDC-NH2 exhibited a greatly enhanced OER performance with ultralow Tafel slopes of 45 mV dec-1 and overpotentials of 280 mV at 10 mA cm-2 when the BDC-NH2 ligand was adopted, even superior to commercial IrO2 (323 mV) and most of the reported pristine MOFs as OER electrodes. Much higher structural stability was proven. The detailed structure-property relationship and mechanism are discussed. In a word, this work provides a very important theoretical basis for the design and exploration of new MOF electrocatalysts.

Iron-Based Metal-Organic Framework System as an Efficient Bifunctional Electrocatalyst for Oxygen Evolution and Hydrogen Evolution Reactions.

The fabrication of highly efficient and sustainable electrocatalysts used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is exceedingly challenging and warranted for overall water splitting. In this work, we successfully synthesized a series of metal-organic frameworks (MOFs), namely, as Fe2M-MOF (M = Fe, Co, Ni, Zn, Mn; H4L = 3,3,5,5'-azoxybenzenetetracarboxylic acid) under a simple and mild condition, in which the Fe3 cluster as a basic building unit was replaced by the second kind of metal center; at the same time, a redox-active organic linker was adopted. The Fe2M-MOF system as a multifunctional catalyst realizes great improvement of the OER and HER performances. Among of them, the Fe2Co-MOF catalyst exhibits an extremely low overpotential of 339 mV at a current density of 10 mA cm-2 and a very small Tafel slope of 36.2 mV dec-1 in an alkaline electrolyte for OER. This result has far exceeded the commercial catalyst IrO2. Meanwhile, Fe2Zn-MOF manifests excellent HER activity with a small overpotential of 221 mV at 10 mA cm-2 and a low Tafel slope of 174 mV dec-1. In addition, the good long-term stability for these catalysts can be evaluated under working conditions. Systematic investigations are used to explain the enhanced electrocatalytic mechanism. In conclusion, we provide a simple and effective strategy for the preparation of multifunctional catalysts for energy conversion applications based on a pristine MOF material with redox-active metal centers and organic linkers.

Zeolite-Type Metal Oxalate Frameworks.

While many metal oxalate salts are known, few are known to form zeolite-type topologies. The construction of zeolite types, especially those with low framework density such as RHO, from linear ligands is generally perceived as less likely, because the 180° metal-ligand-metal geometry deviates too much from the established strategy of using ligands with bent coordination geometry (centered around 145°) to mimic the geometry in natural zeolites. We show the general feasibility of using linear ligands for the synthesis of zeolite types by reporting a family of indium oxalate salts with multiple zeolite topologies, including RHO, GIS, and ABW. Of particular interest is the synthesis of a zeolite RHO net with double 8-rings and large alpha cages, which are highly desirable zeolite features.

A Dual-Functional Luminescent MOF Sensor for Phenylmethanol Molecule and Tb3+ Cation.

A highly luminescent porous metal-organic framework Cd3(L)2.5(4-PTZ)(DMF)3, labeled as NBU-9, has been designedly synthesized based on Cd(NO3)2·4H2O and mixed ligands of 4-(1 H-tetrazol-5-yl)pyridine (4-HPTZ) with N-coordinated sites and thiophene-2,5-dicarboxylic acid (H2L) with heteroatomic (S) ring and carboxylate groups in N, N-dimethylformamide (DMF) at 100 °C for 3 days. The interesting result is that this compound NBU-9 can be also obtained via the mixed raw materials of Cd(NO3)2·4H2O, 4-cyanopyridine, NaN3, and H2L under solvothermal condition at a higher temperature of 140 °C for 3 days, involving in situ ligand synthesis of 4-HPTZ. Its structure was indentified by single-crystal X-ray study, powder X-ray diffraction, element analysis, and TGA results. Structural analysis shows that the three-dimensional framework of NBU-9 contains cubic channels of 9.59 × 10.26 Å2 covered by a large number of open S- and O-coordinated sites and can be simplified into a 8-connected uninodal eca net with high potential solvent accessible volumes of 34.1%. Its luminescent properties demonstrate that NBU-9 as a multifunctional sensory material realizes the selective detection for the phenylmethanol molecule on the basis of fluorescence quenching mechanism and effectively sensitizing the visible emitting of the Tb3+ cation based on luminescence enhancement.

Hierarchical Two-Dimensional Conductive Metal-Organic Framework/Layered Double Hydroxide Nanoarray for a High-Performance Supercapacitor.

A novel hierarchical nanoarray material based on a two-dimensional metal-organic framework (Ni-CAT) and a layered double hydroxide (NiCo-LDH) was fabricated on a nickel foam substrate. By taking advantage of the regular nanostructure and making full use of the high porosity and excellent conductivity, the hybrid material exhibits a high areal capacitance for a supercapacitor (3200 mF cm-2 at 1 mA cm-2).

A Series of Multifunctional Metal-Organic Frameworks Showing Excellent Luminescent Sensing, Sensitization, and Adsorbent Abilities.

A series of highly luminescent-active metal-organic frameworks (MOFs) 1-3 with hierarchical pores have been rationally constructed and fully characterized. The predesigned semi-rigid hexacarboxylate ligand hexa[4-(carboxyphenyl)oxamethyl]-3-oxapentane acid (H6 L) has been adapted with various space-directed N donors (i.e., 2,2'-bipyridine, 4,4'-di(1H-imidazol-1-yl)-1,1'-biphenyl, and 1,3,5-tri(1H-imidazol-1-yl)benzene) from a bidentate V-shape to a tridentate Y-shape. This family of multifunctional MOF materials represents a variety of potential applications in the following aspects: first, as luminescent sensors that show a fast and sensitive detection for pollutant CrO4 (2-) and Cr2 O7 (2-) ions in aqueous media; second, as adsorbents that can rapidly remove harmful organic dyes; third, as an antenna that can effectively sensitize visible-light-emitting Tb(3+) ions. These multifunctional MOF materials combine optical-sensing, adsorption, and sensitization properties, thus are very useful in many potential applications. Furthermore, these materials have proved to be reusable.

Lanthanide metal-organic frameworks showing luminescence in the visible and near-infrared regions with potential for acetone sensing.

The luminescent properties of a family of lanthanide metal-organic frameworks LnL (Ln=Y, La-Yb, except Pm; L=4,4'-({2-[(4-carboxyphenoxy)methyl]-2-methylpropane-1,3-diyl}bis{oxy})dibenzoic acid) have been explored, and the energy-transfer process in the compounds has been carefully analyzed. The visible-emitting Tb(0.08)Gd(0.92)L and the near-infrared (NIR)-luminescent Yb(0.10)Gd(0.90)L show excellent optical performances and can be considered as fluorescent probes for acetone sensing based on luminescence quenching effects arising from host-guest interactions. Moreover, GdL exhibits a strong second harmonic generation (SHG) signal 6.1 times that of potassium dihydrogen phosphate (KDP) and an outstanding phase-matchable effect. These lanthanide compounds combining fluorescent and nonlinear optical (NLO) properties could meet further requirements as multifunctional materials.

(FeMnCe)-co-doped MOF-74 with significantly improved performance for overall water splitting.

Developing inexpensive electrocatalysts with high activity and stability is of great value for overall water splitting. In this work, we designed a series of 3d-4f (FeMnCe)-trimetallic MOF-74 with different ratios of 3d- and 4f-metal centers. Among them, FeMn6Ce0.5-MOF-74/NF exhibited the best electrocatalytic performance for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline solution. It only requires a low overpotential of 281 mV@100 mA cm-2 for OER and 186 mV@-10 mA cm-2 for HER in 1 M KOH. With FeMn6Ce0.5-MOF-74/NF as the anode and cathode in the overall water splitting system, only 1.65 V is needed to deliver a current density of 10 mA cm-2. In particular, for the as-fabricated FeMn6Ce0.5-MOF-74/NF||Pt/C cell unit, only 1.40 V is needed to achieve 10 mA cm-2. Therefore, the successful design of 3d-4f mixed-metallic MOF-74 provides a new viewpoint to develop highly efficient non-precious metal electrocatalysts.

One-step synthesis of 2D@3D hollow Prussian blue analogue as a high-performance bifunctional electrochemical sensor.

Prussian blue analogues (PBAs) are a family of classic coordination polymers. They have been widely applied in various fields including electrochemical sensors. Cubic nanoparticle structure is their common morphology. It is still a great challenge to design a hollow and two-dimensional (2D) PBA material. Of course, it will be a significant surprise if a hollow cube and 2D sheet can be integrated into one material. In this work, we designed a simple one-step synthetic strategy and resolved the above difficulty, wherein a hollow cubic PBA covered by 2D ultrathin nanosheets was successfully constructed, namely hollow tremella-like PBA (HTPBA). Furthermore, Ni foam (NF) as a substrate was introduced to obtain a self-supporting HTPBA/NF-12 electrode. HTPBA/NF-12, as a bifunctional electrochemical sensor electrode, exhibited distinguished catalytic performance towards glucose and nitrite, including remarkable selectivity, reproducibility, sensitivity for glucose (21 410 µA mM-1 cm-2) and nitrite (1248 µA mM-1 cm-2), wide linear range of 2-1250 µM and 5-3380 µM, along with low detection limit of 0.056 µM and 0.38 µM, respectively. More importantly, HTPBA/NF-12 electrodes possessed good reusability and practicability even in goat serum. In this study, we developed a simple and effective strategy to fabricate 2D@3D PBA material with excellent electrocatalytic activity and provide a totally new viewpoint in the PBA sensing field.

Iron-Cobalt-Cerium Multimetallic Oxides Derived from Prussian Blue Precursors: Enhanced Oxygen Evolution Electrocatalysis.

Exploring non-precious metal-based electrocatalysts is still challenging in 21st century. In this work, a series of hexagonal bipyramidal Ce-based PBA materials as precursors with different Fe/Co metal ratios, namely as CeFex Co1-x -PBA, are successfully constructed via co-precipitation method and converted into corresponding metal oxides (denoted as Fex Co1-x CeOy ) via thermal treatment. Then, they as electrocatalysts realize highly efficient oxygen evolution reaction (OER). Especially, as-synthesized Fe0.7 Co0.3 CeOy electrocatalyst shows very low overpotentials of 320 mV at the current density of 10 mA cm-2 and the Tafel slop of 98.4 mV dec-1 in 1 M KOH with remarkable durability for 24 h, which was due to the synergistic effect of multi-metal FeCoCe centers. Furthermore, a two-electrode cell of Fe0.7 Co0.3 CeOy /NF||Pt/C/NF realizes outstanding overall water splitting with a voltage of only 1.71 V at 10 mA cm-2 and remarkable long-term durability, that is even superior to benchmark IrO2 /NF||Pt/C/NF counterpart.

Vanadium-Based Trimetallic Metal-Organic-Framework Family as Extremely High-Performing and Ultrastable Electrocatalysts for Water Splitting.

This is the first time that the pore-space-partition (PSP) strategy is being successfully applied in the electrochemical field for water splitting, realizing the highly efficient construction of a series of ultrastable pristine MOF electrocatalysts. On integrating the vanadium-based trimetallic building cluster (M2V), the target M2V-MOFs exhibit excellent electrocatalytic activity for HER, OER, and water splitting. In particular, ultralow overpotentials of 314 and 198 mV for Fe2V-MOF as OER and HER electrocatalysts, respectively, can drive a current density of 10 mA cm-2. The fabricated Fe2V-MOF||Pt/C two-electrode configuration for the overall water splitting yields a current density of 10 mA cm-2 at only 1.6 V vs RHE, which is superior to that of the commercial IrO2||Pt/C couple. Notably, high structural and chemical stabilities still can be observed in alkaline condition. This work opens up an exciting pathway to design efficient and stable electrocatalysts based on pristine MOF by integrating the PSP strategy and multimetallic centers.

Synthesis and Applications of Prussian Blue and Its Analogues as Electrochemical Sensors.

Prussian blue (PB) and its analogue (PBA) are a kind of representative cyanide-based coordination polymer. They have received enormous research interest and have shown promising applications in the electrochemical sensing field due to their excellent electrochemical activity and unique structural characteristics including open framework structure, high specific surface area, and adjustable metal active sites. In this review, we summarize the latest research progress of PB/PBA as an electrochemical sensor in detail from three aspects: fabrication strategy, synthesis method and electrochemical sensor application. For the fabrication strategy, we discussed different fabrication methods containing the combination of PBA and carbon materials, metal nanoparticles, polymers, etc., respectively, as well as their corresponding sensing mechanism for improving performance. We also presented the synthesis methods of PB/PBA materials in detail, such as: coprecipitation, hydrothermal and electrodeposition. In addition, the effects of different methods on the morphology, particle size and productivity of PB/PBA materials are also concluded. For the application of electrochemical sensors, the latest progress of such materials as electrochemical sensors for glucose, H2 O2 , toxic compounds, and biomolecules have been summarized. Finally, we conclude remaining challenges of PB/PBA-based materials as electrochemical sensors, and provide personal perspectives for future research in this field.

Synthesis, crystal structures, and luminescent properties of two series' of new lanthanide (III) amino-carboxylate-phosphonates.

Hydrothermal reactions of lanthanide(III) chlorides with 4-HOOC-C(6)H(4)-CH(2)NHCH(2)PO(3)H(2) (H(3)L) at different ligand-to-metal (L/M) ratios afforded nine new lanthanide(III) carboxylate-phosphonates with two types of 3D network structures, namely, LnCl(HL)(H(2)O)(2) (Ln = Sm, 1; Eu, 2; Gd, 3; Tb, 4; Dy, 5; Er, 6) and [Ln(2)(HL)(H(2)L)(L)(H(2)O)(2)].4H(2)O (Ln = Nd, 7; Sm, 8; Eu, 9). Compounds 1-6 are isostructural and feature a 3D network in which the LnO(7)Cl polyhedra are interconnected by bridging CPO(3) tetrahedra into 2D inorganic layers parallel to the bc plane. These layers are further cross-linked by organic groups of the carboxylate-phosphonate ligands via the coordination of the carboxylate groups into a pillared-layered architecture. Compounds 7-9 are also isostructural and feature a 3D open-framework composed of 1D lanthanide(III) phosphonate inorganic slabs which are further bridged by organic groups of the carboxylate-phosphonate liagnds via the coordination of the carboxylate groups, forming large 1D tunnels along the b-axis which are filled by lattice water molecules. Luminescent measurements indicate that compounds 2, 4, and 5 show strong emission bands in red, green, and yellow light region, respectively. Magnetic properties of 2, 3, 5, and 7 have also been studied.

A series of new manganese(II) sulfonate-arsonates with 2D layer, 1D chain, and 0D clusters structures.

Hydrothermal reactions of manganese(II) salts with o-sulfophenylarsonic acid (o-HO(3)S-C(6)H(4)-AsO(3)H(2), H(3)L) afforded Mn(3)(L)(2)(H(2)O)(3).H(2)O (1) with a layered structure. When 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy), and 2,2':6',2''-terpyridine (terpy) were used as auxiliary chelating ligands, a series of mixed-ligand manganese(II) sulfonate-arsonates with lower dimensional structures, namely, [Mn(HL)(phen)(2)](2).8.5H(2)O (2), Mn(HL)(phen)(2)(H(2)O).2H(2)O (3), [Mn(HL)(bipy)(2)][Mn(H(2)L)(bipy)(2)](ClO(4)).3H(2)O (4), [Mn(HL)(phen)][Mn(HL)(phen)(H(2)O)] (5), [Mn(2)(HL)(phen)(4)(H(2)O)](ClO(4))(2).4H(2)O (6), [Mn(2)(HL)(phen)(4)(H(2)O)](ClO(4))(2).H(2)O (7), Mn(2)(HL)(2)(bipy)(3)(H(2)O).H(2)O (8), [Mn(HL)(terpy)](2) (9), Mn(7)(OH)(2)(L)(4)(phen)(8).10H(2)O.phen (10), and Mn(HL)(bipy)(H(2)O).2H(2)O (11) have been obtained. 2-4 are mononuclear (4 contains two different mononuclear cluster units) whereas 5-9 feature three types of isolated dinuclear cluster units in which the two Mn(2+) ions are bridged by one or two sulfonate-arsonate ligands. 10 exhibits an interesting heptanuclear cluster in which the Mn(2+) centers are bridged by arsonate, sulfonate groups and hydroxyl anions. 11 features a one-dimensional (1D) chain in which two neighboring Mn(2+) centers are bridged by an arsonate group of a sulfonate-arsonate ligand. Magnetic measurements indicate that 1 exhibits an unprecedented spin topology and behaves as a homospin ferrimagnet whereas 2-4 are essentially paramagnetic. 5-9 and 11 are weakly antiferromagnetic.

MOF-Derived Bimetallic CoFe-PBA Composites as Highly Selective and Sensitive Electrochemical Sensors for Hydrogen Peroxide and Nonenzymatic Glucose in Human Serum.

The fabrication of two-dimensional (2D) metal-organic frameworks (MOFs) and Prussian blue analogues (PBAs) combines the advantages of 2D materials, MOFs and PBAs, resolving the poor electronic conductivity and slow diffusion of MOF materials for electrochemical applications. In this work, 2D leaflike zeolitic imidazolate frameworks (Co-ZIF and Fe-ZIF) as sacrificial templates are in situ converted into PBAs, realizing the successful fabrication of PBA/ZIF nanocomposites on nickel foam (NF), namely, CoCo-PBA/Co-ZIF/NF, FeFe-PBA/Fe-ZIF/NF, CoFe-PBA/Co-ZIF/NF, and Fe/CoCo-PBA/Co-ZIF/NF. Such fabrication can effectively reduce transfer resistance and greatly enhance electron- and mass-transfer efficiency due to the electrochemically active PBA particles and NF substrate. These fabricated electrodes as multifunctional sensors achieve highly selective and sensitive glucose and H2O2 biosensing with a very wide detective linear range, extremely low limit of detection (LOD), and good stability. Among them, CoFe-PBA/Co-ZIF/NF exhibits the best sensing performance with a very wide linear range from 1.4 µM to 1.5 mM, a high sensitivity of 5270 µA mM-1 cm-2, a low LOD of 0.02 µM (S/N = 3), and remarkable stability and selectivity toward glucose. What is more, it can realize excellent detection of glucose in human serum, demonstrating its practical applications. Furthermore, this material as a multifunctional electrochemical sensor also manifests superior detection performance against hydrogen peroxide with a wide linear range of 0.2-6.0 mM, a high sensitivity of 196 µA mM-1 cm-2, and a low limit of detection of 1.08 nM (S/N = 3). The sensing mechanism for enhanced performance for glucose and H2O2 is discussed and proved by experiments in detail.

Rationally designed trimetallic Prussian blue analogues on LDH/Ni foam for high performance supercapacitors.

Rational design of a Prussian blue analogue (PBA)@Ni-Co layered double hydroxide (NiCo-LDH) nanocomposite electrode material is vitally important for synthesizing high-performance supercapacitor electrodes. In this work, such nanocomposite electrode materials were successfully fabricated by a facile hydrothermal method. Firstly, three-dimensional (3D) regulated NiCo-LDH nanosheets with high interlayer space were grown on nickel foam under mild synthetic conditions. Then these nanosheets as a precursor were in situ converted into the target PBA@NiCo-LDH/NF nanocomposite electrode by a facile thermal ion-exchange reaction with potassium ferricyanide (K3[Fe(CN)6]). A series of PBA@NiCo-LDH/NF nanocomposite electrodes were fabricated with different ratios of Ni and Co and reaction temperatures. Their structures and morphologies were characterized by X-ray diffraction (XRD), FT-IR and scanning electron microscopy (SEM). Electrochemical investigation reveals that the PBA@Ni0.4Co0.6-LDH electrode exhibits the best electrochemical performance with an area specific capacitance of 2004.26 mF cm-2 at 1 mA cm-2, which is much higher (about three times) than the properties of each single component. All results demonstrate that (1) high-performance composite electrodes can be effectively fabricated and (2) fabrication of such composites is highly necessary and important.

Syntheses and crystal structures of novel manganese(II) or cadmium(II) arsonates with dinuclear clusters or 1D arrays.

Hydrothermal reactions of cadmium(II) or manganese(II) salts with aryl arsenic acids RAsO(3)H(2) (R = C(6)H(5)-, H(2)L(1); 3-NO(2)-4-OH-C(6)H(3)-, H(3)L(2)) and 1,10-phenanthroline (phen) led to six new cadmium(II) and manganese(II) organo arsonates, namely, Cd(phen)(HL(1))(2)(H(2)O) (1), M(phen)(H(2)L(2))(2) (M = Mn, 2; Cd, 3), [M(phen)(2)(H(2)L(2))](ClO(4)) x (H(2)O) (M = Mn, 4; Cd, 5), and [Mn(phen)(2)(HL(1))](ClO(4)) x (H(2)O) (6). The structures of 1, 4, and 5 contain two types of dinuclear clusters, whereas 2 and 3 exhibit 1D chains based on dinuclear M(2)(mu-O)(2) cluster units further bridged by arsonate ligands. Compound 6 features a 1D helical chain in which neighboring two metal centers are bridged by one arsonate ligand. Magnetic property measurements on compounds 2, 4, and 6 indicate that there exist very weak antiferromagnetic interactions between magnetic centers in all three compounds. Compounds 1-6 display typical ligand-centered fluorescence emission bands.