Controlled Construction of Metal–Organic Frameworks: Hydrothermal Synthesis,X‐ray Structure,and Heterogeneous Catalytic Study

The role of pH in the formation of metal–organic frameworks (MOFs) has been studied for a series of magnesium‐based carboxylate framework systems. Our investigations have revealed the formation of five different zero‐dimensional (0D) to three‐dimensional (3D) ordered frameworks from the same reaction mixture, merely by varying the pH of the medium. The compounds were synthesized by the hydrothermal method and characterized by single‐crystal X‐ray diffraction. Increase of the pH of the medium led to abstraction of the imine hydrogen from the ligand and a concomitant increase in the OH^? ion concentration in the solution, facilitating the construction of higher dimensional framework compounds. A stepwise increase in pH resulted in a stepwise increase in the dimensionality of the network, ultimately leading to the formation of a 3D porous solid. A gas adsorption study of the 3D framework compound confirmed its microporosity with a BET surface area of approximately 450 m² g^?1. Notably, the 3D framework compound catalyzes aldol condensation reactions of various aromatic aldehydes with acetone under heterogeneous conditions.     

Super flexibility of a 2D Cu-based porous coordination framework on gas adsorption in comparison with a 3D framework of identical composition: framework dimensionality-dependent gas adsorptivities

Selective synthetic routes to coordination polymers [Cu(bpy)(2)(OTf)(2)](n) (bpy = 4,4'-bipyridine, OTf = trifluoromethanesulfonate) with 2- and 3-dimensionalities of the frameworks were established by properly choosing each different solvent-solution system. They show a quite similar local coordination environment around the Cu(II) centers, but these assemble in a different way leading to the 2D and 3D building-up structures. Although the two kinds of porous coordination polymers (PCPs) both have flexible frameworks, the 2D shows more marked flexibility than the 3D, giving rise to different flexibility-associated gas adsorption behaviors. All adsorption isotherms for N(2), CO(2), and Ar on the 3D PCP are of type I, whereas the 2D PCP has stepwise gas adsorption isotherms, also for CH(4) and water, in addition to these gases. The 3D structure, having hydrophilic and hydrophobic pores, shows the size-selective and quadrupole-surface electrical field interaction dependent adsorption. Remarkably, the 2D structure can accommodate greater amounts of gas molecules than that corresponding to the inherent crystallographic void volume through framework structural changes. In alcohol adsorption isotherms, however, the 2D PCP changes its framework structure through the guest accommodation, leading to no stepwise adsorption isotherms. The structural diversity of the 2D PCP stems from the breathing phenomenon and expansion/shrinkage modulation.     

Entanglement of individual coordination polymers having helicates as building intermediates

A series of Ag(I) coordination compounds, from one-dimensional chains to 3D porous frameworks, were achieved from N,N'-bis[1-(2-pyrazinyl)ethylidene]benzil dihydrazone, L, via self-assembly, using helicates as effective secondary building units. Compound 2 [(Ag(2.75)L)(NO(3))(2.75)] was comprised of two opposite-handed 3D frameworks formed by connecting the 4(1) helical chains into (10(3)-b) nets. The pairs of the racemic 3D frameworks were connected through additional silver(I) centers and entangled each other forming a racemic 3D net. Compound 3 [(Ag(13)L(8))(BF(4))(13)(H(2)O)(12)] was comprised of a 3D framework that was constructed from double-helical building intermediates Ag(2)L(2) with one-dimensional infinite chains being threaded into the large voids of a 3D framework to form a weave structure. The ladder-like chains in compound 4 [(Ag(3)L(2))(ClO(3))(3)(CH(3)OH)(2)(CH(3)CN)] were formed by the addition of excess NaClO(3) into the methanol solution containing AgNO(3) and the ligand L, and the zigzag chains in compound 5 [(Ag(2)L(2))(ClO(4))(2)(CH(3)CN)(2)] were constructed by the addition of excess NaClO(4) into an acetonitrile solution containing AgNO(3) and the ligand L.     

Borromean-entanglement-driven assembly of porous molecular architectures with anion-modified pore space

A series of metal-organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1?Mn?OH(-), 2?Mn?SO(4)(2-), 3?Mn?bdc(2-), 4?Eu?SO(4)(2-) (H(2)BpybcCl(2) = 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridinium dichloride, H(2)bdc = 1,4-benzenedicarboxylic acid) have been obtained by a self-assembly process. Single-crystal X-ray-diffraction analysis revealed that all of these compounds contained the same n-fold 2D→3D Borromean-entangled topology with irregular butterfly-like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non-interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1?Mn?OH(-) further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π-conjugated structures.     

pH法研究UO2+2与甘氨酰替甘氨酸、白氨酸和四咪噻唑的络合物

本文应用pH法测定了UO₂⁺²与甘氨酰替甘氨酸、白氨酸和d,l-2,3,5,6-四氢-6-苯基咪唑[2,1-6]噻唑的络合物的逐级稳定常数,分别得出,UO₂⁺²-甘氨酰替甘氨酸体系:β₁=5.7×10³和β₂=1.4×10¹⁰;UO₂⁺²-白氨酸体系:β₁=4.0×10⁵和β₂=1.6×10¹³,以及UO₂⁺²-d,l-2,3,5,6-四氢-6-苯基咪唑(2,1-6)噻唑体系:β₁=6.5×10⁴和β₂=2.0×10¹⁰(25℃,μ=0.1,KCl维持)。同时,将徐光宪的溶液中络合物吸附平衡理论引入pH法研究络合物稳定常数中。     

Polarographic investigation of Cu(II) complexes with N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine

During investigation of the formation of Cu(2+) ion complexes with N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine (Quadrol-Q) by means of constant current polarography (20 degrees C, ionic strength J = 3 mol l(-1)), the possibility of the formation of two complex compounds; CuQ(2+) and CuQ(2+)(2), was shown within the pH range from 6 to 8. The logarithms of the stability constants for these compounds are 10.6 +/- 0.5 and 14.6 +/- 0.4 respectively. Cu(II) complexation increases sharply when the pH increases from 8 to 10. It was shown that the data at a pH of greater than 10 are in accordance with the existence of the hydroxy complexes CuQ(OH)(2) and CuQ(2)(OH)(2), the logarithms of the stability constants being 26.9 +/- 0.5 and 29.1 +/- 0.3.     

Porous anionic, cationic, and neutral metal-carboxylate frameworks constructed from flexible tetrapodal ligands: syntheses, structures, ion-exchanges, and magnetic properties

A series of coordination polymers with anionic, cationic, and neutral metal-carboxylate frameworks have been synthesized by using a flexible tetrapodal ligand tetrakis[4-(carboxyphenyl)oxamethyl] methane acid (H(4)X). The reactions between divalent transition-metal ions and H(4)X ligands gave [M(3)X(2)]·[NH(2)(CH(3))(2)](2)·8DMA (M = Co (1), Mn (2), Cd(3)) which have anionic metal-carboxylate frameworks with NH(2)(CH(3))(2)(+) cations filled in channels. The reactions of trivalent metal ions Y(III), Dy(III), and In(III) with H(4)X ligands afforded cationic metal-carboxylate frameworks [M(3)X(2)·(NO(3))·(DMA)(2)·(H(2)O)]·5DMA·2H(2)O (M = Y(4), Dy(5)) and [In(2)X·(OH)(2)]·3DMA·6H(2)O (6) with the NO(3)(-) and OH(-) serving as counterions, respectively. Moreover, a neutral metal-carboxylate framework [Pb(2)X·(DMA)(2)]·2DMA (7) can also be isolated from reaction of Pb(II) and H(4)X ligands. The charged metal-carboxylate frameworks 1-5 have selectivity for specific counterions in the reaction system, and compounds 1 and 2 display ion-exchange behavior. Moreover, magnetic property measurements on compounds 1, 2, and 5 indicate that there exists weak antiferromagnetic interactions between magnetic centers in the three compounds.     

Transformation from a 2D stacked layer to 3D interpenetrated framework by changing the spacer functionality: synthesis, structure, adsorption, and magnetic properties

Two novel coordination polymers of Cu(II), viz. [Cu(bipy)(1,4-napdc)(H2O)2]n and {[Cu(bpe)1.5(1,4-napdc)](H2O)}n (bipy=4,4'-bipyridine; bpe=1,2-bis(4-pyridyl)ethane; 1,4-napdc2-=1,4-naphthalenedicarboxylate), have been synthesized and structurally characterized by changing only the pillar motifs. Both the compounds crystallize by slow evaporation from the ammoniacal solution of the as-synthesized solid. Framework 1 crystallizes in monoclinic crystal system, space group P2/n (No. 13), with a=11.028(19) A, b=11.16(3) A, c=7.678(13) A, beta=103.30(5) degrees, and Z=2. Framework 2 crystallizes in triclinic system, space group, P (No. 2), a=10.613(4) A, b=10.828(10) A, c=13.333(9) A, alpha=85.25(9) degrees, beta=82.59(6) degrees, gamma=60.37(5) degrees, and Z=2. The structure determination reveals that has a 2D network based on rectangular grids, where each Cu(II) is in 4+2 coordination mode. The 2D networks stacked in a staggered manner through the pi-pi interaction to form a 3D supramolecular network. In the case of, a {Cu(bpe)1.5}n ladder connected by 1,4-napdc2- results a 2D cuboidal bilayer network and each bilayer network is interlocked by two adjacent identical network (upper and lower) forming 3-fold interpenetrated 3D framework with small channel along the c-axis, which accommodates two water molecules. The TGA and XRPD measurements reveal that both the frameworks are stable after dehydration. Adsorption measurements (N2, CO2, and different solvents, like H2O, MeOH, etc.) were carried out for both frameworks. Framework shows type-II sorption profile with N2 in contrast to H2O and MeOH, which are chemisorbed in the framework. In case of, only H2O molecules can diffuse into the micropore, whereas N2, CO2, and MeOH cannot be adsorbed, as corroborated by the smaller channel aperture. The low-temperature (300-2 K) magnetic measurement of and reveals that both are weakly antiferromagnetically coupled (J=-1.85 cm-1, g=2.02; J=-0.153 cm-1, g=2.07), which is correlated by the magnetic pathway to the corresponding structure.     

Syntheses, structures, ionic conductivities, and magnetic properties of three new transition-metal borophosphates Na5(H3O){M(II)3[B3O3(OH)]3(PO4)6}.2H2O (M(II) = Mn, Co, Ni)

Three new open-framework transition-metal borophosphates Na5(H3O){M(II)3[B3O3(OH)]3(PO4)6}.2H2O (M(II) = Mn, Co, Ni) (denoted as MBPO-CJ25) have been synthesized under mild hydrothermal conditions. Single-crystal X-ray diffraction analyses reveal that the three compounds possess isostructural three-dimensional (3D) open frameworks with one-dimensional 12-ring channels along the [001] direction. Notably, the structure can also be viewed as composed of metal phosphate layers [M(II)(PO4)2]4- with Kagomé topology, which are further connected by [B3O7(OH)] triborates, giving rise to a 3D open framework. The guest water molecules locate in the 12-ring channels. Partial Na+ ions reside in the 10-ring side pockets within the wall of the 12-ring channels, and the other Na+ ions and protonated water molecules locate in the 6-ring windows delimited by MO6 and PO4 polyhedra to compensate for the negative charges of the anionic framework. These compounds show a high thermal stability and are stable upon calcinations at ca. 500 degrees C. Ionic conductivities, due to the motion of Na+ ions, are measured for these three compounds. They have similar activation energies of 1.13-1.25 eV and conductivities of 2.7 x 10(-7)-9.9 x 10(-7) S cm(-1) at 300 degrees C. Magnetic measurements reveal that there are very weak antiferromagnetic interactions among the metal centers of the three compounds. Crystal data: MnBPO-CJ25, hexagonal, P6(3)/m (No. 176), a = 11.9683(5) A, c = 12.1303(6) A, and Z = 2; CoBPO-CJ25, hexagonal, P6(3)/m (No. 176), a = 11.7691(15) A, c = 12.112(2) A, and Z = 2; NiBPO-CJ25, hexagonal, P6(3)/m (No. 176), a = 11.7171(5) A, c = 12.0759(7) A, and Z = 2.     

Two solvent and temperature dependent copper(II) compounds formed by a flexible ligand: syntheses, structures and SC-SC transformation

A nonporous neutral framework [CuCl(2)(m-bttmb)(2)](n) (1) was changed into a porous ionic {[Cu(m-bttmb)(2)(H(2)O)Cl]Cl(CH(3)CN)(0.5)(H(2)O)(2.75)}(n) (2) by simply increasing the amount of CH(3)CN in the mixed solvent (CH(3)CN and H(2)O) or temperature in the reactions of CuCl(2)·2H(2)O with 1,3-bis(triazol-1-ylmethyl)-2,4,6-trimethylbenzene (m-bttmb). 1 undergoes transformation into 2 when treated with CH(3)CN. Both 1 and 2 have 2D 4-connected (4,4) network architectures but in different packing arrangements. These compounds have been characterized by single-crystal X-ray diffraction analysis, elemental analysis, IR spectra and thermogravimetric analysis. This work may provide a way to control the formation of neutral or ionic frameworks, as well as porosities by adjusting the polarity and components of the solvents.     

Structure-directing and template roles of aromatic molecules in the self-assembly formation process of 3D holmium-succinate MOFs

Two new holmium-succinate frameworks have been synthesized by hydrolysis in situ of the succinylsalicylic acid under different hydrothermal conditions. Compound 1, [Ho(2)(C(4)H(4)O(4))(3)(H(2)O)(2)]·0.33(C(7)H(6)O(3)), P ?i space group, has a novel structure composed by 1D-SBUs consisting of [HoO(9)] chains of polyhedra linked by the succinate ligands giving a 3D framework. Compound 2, [Ho(2)(C(4)H(4)O(4))(3)(H(2)O)(2)], also belonging to the P ?i space group, has a denser structure. The role of the in-situ-generated salicylic acid on formation of both structures is studied by means of a synthesis design methodology. A topological study of the new holmium succinate compounds in comparison with the previously reported 3D holmium-succinate framework is performed here.     

Cr^3^+的水解聚合作用IV.两种"根+节"体系之间的过渡状态

The hydrolytic polymerization of chromium (III) ion in 0.040, 0.060, 0.080 and 0.160M Cr(NO3)3 solutions was studied pH-metrically in the medium of 0.5M NaNO3 at 40+/-1 C. The average number of OH- bound per Cr^3^+ at different pH was designated as Z, the gighest value of Z was found to be about 1.0. A family of curves of Z(pH)B, each at a definite concentration B of Cr(NO3)3, was obtained. The values of both B and pH were determined from the curves and a linear relationship between -lgB and pH was found for each value of Z. From the slope of each curve of-lgB(pH)z, a value of t was obtained, which increased from 1.51 to 2.06 when Z increased from 0.10 to 1.0. This implied that the polymerized hudrolysis products were of mixed types. The data of different Z value were treated by three different methods, namely, "core + links" method, project strip method and "homoligand formation constant" method. The results obtained showed the existence of "core + links" compounds not only with two hydroxyl bridges as Cr (Cr(OH)2)n^(^3^+^n^)^+(n = 1,2,3) but also with both one and two hydroxy bridges as Cr3(OH)3, indicating that the present system was a transition from t = 2 to t = 1. The hydrolysis constants of the above compounds are as follows: lgβ = -4.19, lgβ33 = -5.28, lgβ = -8.23, lgβ64 = 12.28. The above results are in agreement with those obtained at low and medium concentration of Cr(NO3)3. Furthermore, the constants obtained by means of different methods are in good agreement with each other as well as with those reported in previous papers.     

Influence of the synthetic conditions on the structural diversity of extended manganese-oxalato-1,2-bis(4-pyridyl)ethylene systems

We report herein the synthesis and physicochemical characterization of eight new manganese-oxalato compounds with 1,2-bis(4-pyridyl)ethylene (bpe): {(Hbpe)(2)[Mn(2)(μ-ox)(3)]·～0.8(C(2)H(5)OH)·～0.4(H(2)O)}(n) (1), {[Mn(μ-ox)(μ-bpe)]·xH(2)O}(n) (2), [Mn(2)(μ-ox)(2)(μ-bpe)(bpe)(2)](n) (3), [Mn(μ-ox)(μ-bpe)](n) (4a and 4b), and {[Mn(4)(μ-ox)(3)(μ-bpe)(4)(H(2)O)(4)]·(X)(2)·mY}(n) with X = NO(3)(-) (5a), Br(-) (5b), and ClO(4)(-) (5c) and Y = solvation molecules. The appropriate selection of the synthetic conditions allowed us to control the crystal structure and to design extended 2D and 3D frameworks. Compound 1 is obtained at acid pH values and its crystal structure consists of stacked [Mn(2)(μ-ox)(3)](2-) layers with cationic Hbpe(+) molecules intercalated among them. Compound 2 was obtained at basic pH values with a manganese/bpe ratio of 1:1, and the resulting 3D structure consists of an interpenetrating framework in which metal-oxalato chains are bridged by bpe ligands, leading to a microporous network that hosts a variable number of water molecules (between 0 and 1) depending on the synthetic conditions. Compound 3, synthesized with a manganese/bpe ratio of 1:3, shows a 2D framework in which linear metal-oxalato chains are joined by bis-monodentate 1,2-bis(4-pyridyl)ethylene ligands. The thermal treatment of compound 3 permits the release of one of the bpe molecules, giving rise to two new 2D crystalline phases of formula [Mn(μ-ox)(μ-bpe)](n) (4a and 4b) depending on the heating rate. The open structures of 5a-5c were synthesized in a medium with a high concentration of nitrate, perchlorate, or bromide salts (potassium or sodium as cations). These anions behave as templating agents directing the crystal growing toward a cationic porous network, in which the anions placed in the voids and channels of the structure present high mobility, as inferred from the ionic exchange experiments. Variable-temperature magnetic susceptibility measurements show an overall antiferromagnetic behavior for all compounds, which are discussed in detail.     

Diversity of lanthanide(iii)-2,5-dihydroxy-1,4-benzenedicarboxylate extended frameworks: syntheses, structures, and magnetic properties

Six lanthanide(iii)-2,5-dihydroxy-1,4-benzenedicarboxylate frameworks, namely, [Ln(H(2)-DHBDC)(1.5)(H(2)O)(2)](n) (Ln = La (1) and Pr (2); H(4)-DHBDC = 2,5-dihydroxy-1,4-benzenedicarboxylic acid), {[Nd(H(2)-DHBDC)(1.5)(H(2)O)(3)](H(2)O)}(n) (3), {[Eu(H(2)-DHBDC)(NO(3))(H(2)O)(4)](H(2)O)(2)}(n) (4), and {[Ln(2)(H(2)-DHBDC)(2)(DHBDC)(0.5)(H(2)O)(3)](H(2)O)(4)}(n) (Ln = Gd (5) and Dy (6)), with four different structural types ranging from 1D chain, 2D layer to 3D networks have been synthesized and structurally characterized. Compounds La (1) and Pr (2) are isomorphous and exhibit 3D frameworks with the unique 1D tubular channels. Compounds Nd (3) and Eu (4) are 2D layer and 1D zigzag chain, respectively, which are further extended to 3D supramolecular frameworks through extensive hydrogen bonds. Isomorphous compounds of Gd (5) and Dy (6) are 3D frameworks constructed from secondary infinite rod-shaped metal-carboxylate/hydroxyl building blocks. While the hydroxyl groups as secondary functional groups in the 1D chain of Eu (4) and 2D layer of Nd (3) are not bonded to the lanthanide centers, the hydroxyl groups in the 3D frameworks of La (1), Pr (2), Gd (5), and Dy (6) participate in coordinating to lanthanide centers and thus modify the structural types of theses compounds. The magnetic data of compounds Pr (2), Nd (3), Gd (5), and Dy (6) have been investigated in detail. In addition, elemental analysis, IR spectra, powder X-ray diffraction (PXRD) patterns and thermogravimetric analysis of these compounds are described.     

长链四烷基锡作中性载体的亚硝酸根选择性电极的研究

用亲脂的长链四烷基锡作中性载体制备亚硝酸根选择性电极. 其选择性模式与经典的阴离子交换剂相比有显著不同, 相对硝酸根的电位选择性系数改善约4个数量级. 线性响应区间为1x10^-^1-2x10^-^5mol.dm^-^3, 检测下限为5x10^-^6mol.dm^-^3. 电极斜率在弱性介质中为Nernst响应, 在弱酸性介质中为两倍Nernst响应. 紫外光谱研究发现酸度影响载体与阴离子的多级配位平衡. 电极斜率的变化与此平衡密切相关, 在此基础上给出了对电极斜率的异常变化及电位-pH     

Novel inorganic frameworks constructed from double-four-ring (D4R) units: computational design,structures, and lattice energies of silicate,aluminophosphate, and gallophosphate candidates

The design of new and interesting inorganic frameworks is an ongoing challenge in materials sciences. New structures containing double-four-ring (D4R) units have recently received particular attention. The present work focuses on the computational design of new three-dimensional frameworks made of D4R units exclusively. In a first step, our simulations explore the possible ways to assemble predefined D4R units in 3D space using a sophisticated cascade of simulated annealing/minimizations steps (autoassembly of secondary building units method). While the existing zeotype topologies were successfully generated, new topologies were predicted including very open frameworks containing new types of cages. In a second step, lattice energy minimizations were performed to estimate the viability of these hypothetical frameworks as silicate, aluminophosphaste, and gallophosphate candidates. When comparing the hypothetical structures to existing compounds, our results raise the challenging question of the appropriate chemical composition that should be aimed at for a given framework topology of interest.     

Reversible phase transformation and mechanochromic luminescence of Zn(II)-dipyridylamide-based coordination frameworks

A 1D double-zigzag framework, {[Zn(paps)(2)(H(2)O)(2)](ClO(4))(2)}(n) (1; paps = N,N'-bis(pyridylcarbonyl)-4,4'-diaminodiphenyl thioether), was synthesized by the reaction of Zn(ClO(4))(2) with paps. However, a similar reaction, except that dry solvents were used, led to the formation of a novel 2D polyrotaxane framework, [Zn(paps)(2)(ClO(4))(2)](n) (2). This difference relies on the fact that water coordinates to the Zn(II) ion in 1, but ClO(4)(-) ion coordination is found in 2. Notably, the structures can be interconverted by heating and grinding in the presence of moisture, and such a structural transformation can also be proven experimentally by powder and single-crystal X-ray diffraction studies. The related N,N'-bis- (pyridylcarbonyl)-4,4'-diaminodiphenyl ether (papo) and N,N'-(methylenedi-para-phenylene)bispyridine-4-carboxamide (papc) ligands were reacted with Zn(II) ions as well. When a similar reaction was performed with dry solvents, except that papo was used instead of paps, the product mixture contained mononuclear [Zn(papo)(CH(3)OH)(4)](ClO(4))(2) (5) and the polyrotaxane [Zn(papo)(2)(ClO(4))(2)](n) (4). From the powder XRD data, grinding this mixture in the presence of moisture resulted in total conversion to the pure double-zigzag {[Zn(papo)(2)(H(2)O)(2)](ClO(4))(2)}(n) (3) immediately. Upon heating 3, the polyrotaxane framework of 4 was recovered. The double-zigzag {[Zn(papc)(2)(H(2)O)(2)](ClO(4))(2)}(n) (6) and polyrotaxane [Zn(papc)(2)(ClO(4))(2)](n) (7) were synthesized in a similar reaction. Although upon heating the double-zigzag 6 undergoes structural transformation to give the polyrotaxane 7, grinding solid 7 in the presence of moisture does not lead to the formation of 6. Significantly, the bright emissions for double-zigzag frameworks of 1 and 3 and weak ones for polyrotaxane frameworks of 2 and 4 also show interesting mechanochromic luminescence.     

Syntheses, crystal structures and luminescent properties of new lanthanide(III) organoarsonates

The first examples of lanthanide(III) organoarsonates, Ln(L(1))(H(2)O)(3) (Ln = La (1), H(3)L(1) = 4-hydroxy-3-nitrophenylarsonic acid), Ln(L(1))(H(2)O)(2) (Ln = Nd (2), Gd (3)), and mixed-ligand lanthanide(III) organoarsonates, Ln(2)(HL(1))(2)(C(2)O(4))(H(2)O)(2) (Ln = Nd (4), Sm (5), Eu (6)), were hydrothermally synthesized and structurally characterized. Compounds 1-3 feature a corrugated lanthanide arsonate layer, in which 1D lanthanide arsonate inorganic chains are further interconnected via bridging L(1)(3-) ligands. Compounds 4-6 exhibit a complicated 3D network. The interconnection of the lanthanide(III) ions by the bridging arsonate ligand leads to the formation of a novel 3D framework with long narrow 1D tunnels along the a-axis, with the oxalate anions are located at the above tunnels and bridging with lanthanide(III) ions. Compounds 2 and 4 exhibit the characteristic emission bands of the Nd(III) ion, whereas compound 6 displays the characteristic emission bands of the Eu(III) ion. The magnetic properties of compounds 3-6 were also investigated.     

Novel single-crystal-to-single-crystal anion exchange and self-assembly of luminescent d(10) metal (Cd(II), Zn(II), and Cu(I)) complexes containing C(3)-symmetrical ligands

Ligands L1 and L2' (L1=N,N',N'-tris(4-pyridyl)trimesic amide, L2'=N,N',N'-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide) belonging to an interesting family of tripyridyltriamides with C(3)-symmetry have been utilized to construct 3D porous or hydrogen-bonded frameworks. Through a novel single-crystal-to-single-crystal anion-exchange process, [Cd(L1)(2)(ClO(4))(2)](n) (1c) can be obtained from [Cd(L1)(2)Cl(2)](n) (1b) in the presence of ClO(4)(-) anions. This anion-exchange process is highly selective and only the substitution of Cl(-) by ClO(4)(-) or PF(6)(-) could be realized; Cl(-) was found not to be substituted by BPh(4)(-). This demonstrates that the exchange process depends on the size of the anions in relation to the size of the cavities in the host material (ca. 7.5 A). In addition, the anion-exchange properties of 1 b have also been investigated by means of powder X-ray diffraction (PXRD), elemental analysis (EA), and infrared absorption spectroscopy (IR). Structurally, [Zn(L1)(NO(3))(2)](n)(2) consists of a 2D coordination network with five-coordinate Zn(II) ions. Surprisingly, different trigonal-bipyramidal Zn(II) ions propagate to form distinct respective sheet structures, A and B, which are packed in an A-B-A-B manner in the crystal lattice, and these are hydrogen-bonded to give a 3D extended framework. The molecular structure of [CuI(L2')](n)(3) shows that the Cu(I) ion adopts a distorted tetrahedral geometry, and 3 also forms a 2D coordination network. Significantly, this 2D coordination network is further assembled into a remarkable 3D homochiral framework through triple hydrogen bonding and pi...pi interactions. All of these 3D coordination polymers and/or hydrogen-bonded frameworks are luminescent in the solid state, and their solid-state luminescent properties have been investigated at room temperature and/or at 77 K.     

Self-assembly of polyoxometalate-based metal organic frameworks based on octamolybdates and copper-organic units: from Cu(II), Cu(I,II) to Cu(I) via changing organic amine

Six polyoxometalate (POM)-based hybrid materials have been designed and synthesized based on octamolybdate building blocks and copper-organic units at different pH values under hydrothermal conditions, namely, [H2bbi][Cu(II)(bbi)2(beta-Mo8O26)] (1), [Cu(II)(bbi)2(H2O)(beta-Mo8O26)0.5] (2), [Cu(II)(bbi)2(alpha-Mo8O26)][Cu(I)(bbi)]2 (3), [Cu(II)Cu(I)(bbi)3(alpha-Mo8O26)][Cu(I)(bbi)] (4), [Cu(I)(bbi)]2[Cu(I)2(bbi)2(delta-Mo8O26)0.5][alpha-Mo8O26]0.5 (5), and [Cu(I)(bbi)][Cu(I)(bbi)(theta-Mo8O26)0.5] (6), where bbi is 1,1'-(1,4-butanediyl)bis(imidazole). Their crystal structures have been determined by X-ray diffraction. In compound 1, the bbi ligands with bis-monodentate coordination modes link Cu(II) cations to generate a 2D copper-organic unit with (4, 4) net, which is pillared by the (beta-Mo8O26)(4-) anions to form a 3D framework with alpha-Po topology. The similar copper-organic units are connected alternately by (beta-Mo8O26)(4-) anions to generate a 3D 2-fold interpenetrating (4,6)-connected framework with (4(4) x 6(2))(4(4) x 6(10) x 8) topology in compound 2. Compounds 3 and 4 are supramolecular isomers with polythreaded topology. If Cu (I)...O interactions are considered, the structure of 3 is a novel self-penetrating (3,4,6)-connected framework with (5(2) x 8)2(5(4) x 6 x 8)(4(4) x 6(10) x 10) topology, and the structure of 4 is a (4,6)-connected framework with (4(2) x 6(3) x 7)(5.6(4) x 8)(4(2) x 5(6) x 6(6) x 8)(4(2) x 5(6) x 6(4) x 7 x 8(2)) topology. Different from compounds 3 and 4, compounds 5 and 6 are supramolecular isomers with polythreaded topology based on different octamolybdate isomers. By careful inspection of the structures of 1-6, it is believed that various copper-organic units, which are formed by bbi ligands combined with Cu(II)/Cu(I) cations, octamolybdates with different types and coordination modes, and the nonbonding interactions between polyanions and copper-organic units are important for the formation of the different structures. In addition, with step by step increasing of the amount of organic amine, we have achieved the transformation of Cu(II) ions into Cu(I) ones in different degrees in POMs-based metal-organic frameworks (MOFs) for the first time. The infrared spectra, X-ray powder diffraction, and thermogravimetric analyses have been investigated in detail for all compounds, and the luminescent properties have been also been investigated for compounds 3 and 4.