pH effect on the assembly of metal-organic architectures

Crystal engineering is the rational design and assembly of solid-state structures with desired properties via the manipulation of intermolecular interactions, hydrogen bonding and metal ligand complexation in particular. The heart of crystal engineering is to control the ordering of the building blocks, be they molecular or ionic, toward a specific disposition in the solid state. The relatively weak strength of intermolecular forces with respect to chemical bonding renders the assembly of supramolecular constructs sensitive to external physical and chemical stimuli, with pH condition of the reaction mixture being arguably the most prominent and extensively observed. Using selected examples of constructing metal-organic architectures from recent literature, the influences of pH on the specific ligand forms, the generation and metal coordination of hydroxo ligands, ligand transformation promoted by pH condition changes, pH-dependent kinetics of crystallization of a number of metal-organic architectures are discussed. Current status of this particular areas of research in supramolecular chemistry and materials are assessed and personal perspectives as to toward what directions should this chemistry head are elaborated.NNSFC [20825103, 20721001, 90922031]; 973 project [2007CB815304]; MSTC ; Natural Science Foundation of Fujian Province of China [2008J0010

Slow Magnetic Relaxation in Sandwich-Type Tetranuclear Dysprosium Complex with TMe Q[6](TMe Q[6]=α, α, δ, δ-Tetramethylcucurbit[6]uril)

报道了2个基于四甲基取代六元瓜环的三明治型四核稀土簇合物,[ln4(μ3-OH)4(μ2-OH)2(H2O)4(nO3)2(TME Q[6])2]·(nO3)4·26H2O(ln=dy,1;ln=Tb,2)。晶体结构分析显示2个簇合物包含2个四甲基取代瓜环夹心的四核稀土立方烷结构,[ln4(μ3-OH)4]8+。磁性研究显示化合物1显示了慢磁弛豫行为。由于六元瓜环配体可以有效的传递能量给稀土铽离子,化合物2具有较好的发光性能。Two TMe Q[6]-supported sandwich tetranuclear complexes, [Ln4(μ3-OH)4(μ2-OH)2(H2O)4(NO3)2(TMe Q[6])2](NO3)4·26H2O(Ln=Dy, 1; Ln=Tb, 2), have been prepared and characterized.Crystal structural analysis reveals that both complexes contain a cubane-like [Ln4(μ3-OH)4]8+cluster core sandwiched between two TMe Q[6] macrocycles.Magnetic investigations indicate that complex 1 displays slow magnetization relaxation.Complex 2exhibits intense photoluminescence owing to the efficient energy transfer from TMe Q[6] ligand to Tb3+ion.国家自然科学基金(nos.21422106;21371144;21431005)资助项

A proton-conducting lanthanide metal-organic framework integrated with a dielectric anomaly and second-order nonlinear optical effect

National Basic 25 Research Program of China (973 Program) [2012CB821700]; National Natural Science Foundation of China [20831002, 20502024]; China Postdoctoral Science Foundation [20100481049]; Scientific Research Program from the Education Department of Shaanxi Provincial Government [2013JK0654]; Priming Scientific Research Foundation [BS1115]; Provincial Innovation Training Project [1399]A multifunctional metal-organic framework generated from chiral tricarboxylate ligands and gadolinium ions has been successfully synthesized and characterized. It shows proton conduction, dielectric anomalous behaviour and a second-order NLO effect

Diaquaiminodiacetatonickel(II)

The iminodiacetate dianion in diaquaiminodiacetato-nickel(II), [Ni(C4H5NO4)(H2O)(2)], chelates to the Ni atom through two carboxyl O and one imino N atoms; the six-fold coordination coordination environment comprises these three atoms, the water molecules and the carbonyl O atom of an adjacent dianionic group. The dative Ni<--O linkage leads to the formation of a helical chain running along the a axis of the orthorhombic crystal; adjacent chains are held in a network motif by hydrogen bonds

Disodium bis(1,2,4,5-benzenetetracarboxylato)-dihydroxytetrazincate(II) pyrazine

The tetranuclear dianion of the title compound, Na-2[Zn-4(C10H2O8)(2)(OH)(2)] . C4H4N2, forms a network framework in which the Zn atom exists in a tetrahedral environment, as it is coordinated by the carboxyl O atoms belonging to three different (C10H2O8)(4-) anions as well as by the bridging OH group. Adjacent OH groups are linked together through the uncoordinated heterocycle, which lies on a site of 2/m symmetry. The octahedrally coordinated Na ion, which lies on a site of 2 symmetry, interacts with one O atom of the carboxyl group of two anions and with two O atoms of the ortho-carboxyl groups of two other anions

Polymeric dihydroxydiphthalatotricobalt(II)

In the crystal structure of dihydroxydiphthalatotricobalt(II), [Co-3(C8H4O4)(2)(OH)(2)](n), two of the four independent Co atoms lie at special positions of site symmetry 2. The hydroxy groups link three Co atoms to form a pyramidal Co3O unit, and adjacent Co3O units are linked through the Co base atoms into a honeycomb layer motif. Each of the phthalate dianions uses the O atoms of one carboxyl group to bind to three Co atoms, the bonding mode giving rise to six-coordinate Co atoms

Polymeric tetraapua(1,2,4,5-benzenetetracarboxylato)(pyrazine)dinickel(II) dihydrate

The Ni atom in the title compound, {[Ni-2(C10H2O8)(C4H4N2)( H2O)(4)] . 2H(2)O}(n), exists in an octahedral NO5Ni coordination environment that is defined by the two O atoms of a chelating carboxyl group, the O atom of a monodentate carboxyl group belonging to another carboxylato tetraanion, two water molecules and the N atom of the N-heterocycle. The tetracarboxylato anion and the pyrazine molecule are each located on a center of inversion. The bonding pattern leads to the formation of a layer structure; the layers are linked into a three-dimensional network by extensive hydrogen bonds involving the water molecules and the O atoms of the anionic unit

5-amino-1,3-benzothiazole-2(3H)-thione

The two independent molecules of the title compound, C7H6N2S2, are linked by two secondary amino-thione hydrogen bonds [3.344 (3) and 3.376 (3) Angstrom] to form a flat pseudo-centrosymmetric dimer

A lanthanide-based metal-organic framework with a dynamic porous property

NNSFC [20721001]; MSTC [2007CB815304