Molecular tectonics: design and generation of charge-assisted, H-bonded, hybrid molecular networks based on amidinium cations and thio- or isothio-cyanatometallates

Upon combining the bis-amidinium dication 1-2H(+) with thiocyanatometallate M(SCN)(4)(2-) (M = Pd, Hg) or isothiocyanatometallate Cu(NCS)(4)(2-) anions (behaving as H-bond donor and acceptors, respectively) three new hybrid molecular networks have been obtained in the crystalline phase and structurally characterized by X-ray diffraction on single crystals. Whereas for the combination of tecton 1-2H(+) and both Pd(SCN)(4)(2-) and Hg(SCN)(4)(2-) anions analogous 1-D H-bonded networks were observed, for the Cu(NCS)(4)(2-) anion a 2-D network was obtained. Based on structural features of both components, the formation of the two types of networks is discussed.     

Engineering the structure and magnetic properties of crystalline solids via the metal-directed self-assembly of a versatile molecular building unit

We report the supramolecular chemistry of several metal complexes of N-(4-pyridyl)benzamide (NPBA) with the general formula [Ma(NPBA)2AbSc], where M = Co2+, Ni2+, Zn2+, Mn2+, Cu2+, Ag+; A = NO3-, OAc-; S = MeOH, H2O; a = 0, 1, 2; b = 0, 1, 2, 4; and c = 0, 2. NPBA contains structural features that can engage in three modes of intermolecular interactions: (1) metal-ligand coordination, (2) hydrogen bonding, and (3) pi-pi stacking. NPBA forms one-dimensional (1-D) chains governed by hydrogen bonding, but when reacted with metal ions, it generates a wide variety of supramolecular scaffolds that control the arrangement of periodic nanostructures and form 1- (2-4), 2- (5), or 3-D (6-10) solid-state networks of hydrogen bonding and pi-pi stacking interactions in the crystal. Isostructural 7-9 exhibit a 2-D hydrogen bonding network that promotes topotaxial growth of single crystals of their isostructural family and generates crystal composites with two (11) and three (12) different components. Furthermore, 7-9 can also form crystalline solid solutions (M,M')(NPBA)2(NO3)2(MeOH)2 (M, M' = Co2+, Ni2+, or Zn2+, 13-16), where mixtures of Co2+, Ni2+, and Zn2+ share the same crystal lattice in different proportions to allow the formation of materials with modulated magnetic moments. Finally, we report the effects that multidimensional noncovalent networks exert on the magnetic moments between 2 and 300 K of 1-D (4), 2-D (5), and 3-D (7, 8, 10, and 13-16) paramagnetic networks.     

Synthesis and Crystal Structure of a 1-D Chain Coordination Complex {[Mn2(HCAM)3(H2bipy)]·5H2O}n

The 1-D chain coordination complex of {[Mn2(HCAM)3(H2bipy)]·5H2O}n(H3CAM=4-hydroxypyridine-2,6-dicarboxylic acid,bipy=4,4′-bipyridine) has been synthesized by the reaction of 4-hydroxypyridine-2,6-dicarboxylic acid,4,4′-bipyridine and manganese carbonate under hydrothermal conditions,and its crystal structure was determined by X-ray diffraction method.The crystal belongs to the monoclinic system,space group P21/n with a=10.110(2),b=20.159(4),c=17.861(4) ,β=99.67(3)°,V=3.5884(12) nm3,Mr=901.47,Z=4,Dc=1.669 g·cm-3,μ=0.798 mm-1,F(000)=1840,the final R=0.0713 and wR=0.1853.The complex forms a 1-D chain bridged by HCAM,protonated 4,4-bipyridines link the 1-D chains to construct 2-D networks via N-H…O hydrogen bonds,and networks are further extended via π-π stacking and hydrogen bonds into 3-D supramolecular framework.     

Structural invariance in silver(I) coordination networks formed using flexible four-armed thiopyridine ligands

Two new isomeric, flexible four-armed thioether pyridine-containing ligands 1,2,4,5-tetrakis(3-pyridylmethylsulfanylmethyl)benzene (3tet) and 1,2,4,5-tetrakis(4-pyridylmethylsulfanylmethyl)benzene (4tet) were prepared and characterized. The ligand 3tet gave rise to three isomorphous 3-D networks when reacted with AgClO4 (1), AgPF6 (2), and AgCF3CO2 (3). The topology of the resulting networks was that of the pyrite net. The ligand 4tet gave rise to two isotopological 3-D networks when reacted with AgClO4 (4.2MeCN.2CHCl3) and AgPF6 (5.6MeCN). The topology of these networks was that of the rutile net. A third type of 3-D network of previously unknown topology was formed on reaction with AgCF3SO3 (6.3H2O). The network showed nodes with short topological terms 42.6 and 44.62.87.102. All six networks were binodal and based on three-connected Ag(I) nodes and six-connected ligand-centered nodes. In all of the networks the flexible ligands 3tet and 4tet showed two categories of ligand geometry which in all but one case gave rise to an interligand three-layered pi stack. The networks showed a remarkable lack of dependence on the nature of the counterion and solvent.     

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4'-bipy)(H2O)(4)](4-abs)(2).nH2O (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate) (M = Co,n = 1; M = Mn,n = 2)

Two novel compounds, [Co(4,4'-bipy)(H(2)O)(4)](4-abs)(2).H(2)O (1) and [Mn(4,4'-bipy)(H(2)O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H(2)O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H(2)O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C(22)H(30)CoN(4)O(11)S(2), monoclinic P2(1), a = 11.380(2) A, b = 8.0274(16) A, c = 15.670(3) A, alpha = gamma = 90 degrees, beta = 92.82(3) degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H(2)O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C(22)H(32)MnN(4)O(12)S(2), monoclinic P2(1)/c, a = 15.0833(14) A, b = 8.2887(4) A, c = 23.2228(15) A, alpha = gamma = 90 degrees, beta = 95.186(3) degrees, Z = 4.     

Novel polyoxometalate-templated, 3-D supramolecular networks based on lanthanide dimers: synthesis,structure, and fluorescent properties of [Ln2(DNBA)4(DMF)8][Mo6O19] (DNBA = 3,5-dinitrobenzoate)

The spherical Lindquist type polyoxometalate, Mo(6)O(19)(2)(-), has been used as a noncoordinating anionic template for the construction of novel three-dimensional lanthanide-aromatic monocarboxylate dimer supramolecular networks [Ln(2)(DNBA)(4)(DMF)(8)][Mo(6)O(19)] (Ln = La 1, Ce 2, and Eu 3, DNBA = 3,5-dinitrobenzoate, DMF = dimethylformamide). The title compounds are characterized by elemental analyses, IR, and single-crystal X-ray diffractions. X-ray diffraction experiments reveal that two Ln(III) ions are bridged by four 3,5-dinitrobenzoate anions as asymmetrically bridging ligands, leading to dimeric cores, [Ln(2)(DNBA)(4)(DMF)(8)](2+); [Ln(2)(DNBA)(4)(DMF)(8)](2+) groups are joined together by pi-pi stacking interactions between the aromatic groups to form a two-dimensional grid-like network; the 2-D supramolecular layers are further extended into 3-D supramolecular networks with 1-D box-like channels by hydrogen-bonding interactions, in which hexamolybdate polyanions reside. The compounds represent the first examples of 3-D carboxylate-bridged lanthanide dimer supramolecular "host" networks formed by pi-pi stacking and hydrogen-bonding interactions encapsulating noncoordinating "guest" polyoxoanion species. The fluorescent activity of compound 3 is reported.     

Solvent-induced polymorphism of three-dimensional hydrogen-bonded networks of hexakis(4-carbamoylphenyl)benzene

The crystal structures for three types of three-dimensional (3-D) hydrogen-bonded networks of hexakis(4-carbamoylphenyl)benzene (1), the network morphologies of which depend greatly on crystallization conditions, have been determined. When this compound is crystallized from hot DMSO, the resulting crystals, 1.12DMSO (orthorhombic, Pca2(1)), showed a 3-D hydrogen-bonded porous network (type A) via 1-D catemer chains as a hydrogen-bonding motif of six primary amide groups. The type A network creates chambers surrounded by six molecules of 1 and channels along the c axis to give the highest porosity among the network polymorphs of 1 investigated here. Crystallization from a boiling mixture of n-PrOH and water gave 1.6n-PrOH (monoclinic, P2(1)/c), which exhibits another type of 3-D hydrogen-bonded porous network (type B) via cyclic dimers as another hydrogen-bonding motif of six primary amide groups. The type B network leads to triangle-like channels along the a axis having a cross section of ca. 9.2 x 9.7 x 9.7 A (including van der Waals radii). The crystal structure of 1.H(2)O (monoclinic, P2(1)/c), which was produced under hydrothermal conditions, showed a nonporous 3-D hydrogen-bonded network chain of amide groups (type C) composed of a mixed hydrogen bonding motif of helical catemer chains/cyclic dimer/catemer. Solvent-induced topological isomerism of these 3-D hydrogen-bonded networks of 1 arises from (i) the guest inclusion ability based on a radially functionalized hexagonal structure of 1, (ii) the correlation between the hydrogen bond donor ability of the syn and anti protons of the primary amide group in host 1 and the hydrogen bond acceptor ability of the oxygen atoms of 1 and guest solvents, and (iii) the polarity of the bulk crystallization solvents.     

Syntheses,structures, and properties of two- and three-dimensional coordination polymers based on bis(imidazole) and glutarate ligands

Two new coordination polymers, [Zn(bix)_0.5(glu)]_n (1) and {[Co(bix)(glu)]·4H₂O}_n (2), were synthesized (bix = 1,4-bis(2-methylimidazol-1-ylmethyl)benzene, glu = glutarate). In 1, each Zn(II) is connected by four glu ligands and extend to form a [Zn(glu)]_n 2-D network. Adjacent [Zn(glu)]_n 2-D networks are bridged by bix ligands to construct a 6-connected 3-D network based on the Zn₂ unit. 2 shows an undulated 2-D (4,4) network. The interesting structural feature of 2 is that there are 1-D water chains. The O–H···O hydrogen bond interactions link the 2-D coordination networks and construct the 3-D supramolecular architecture in 2. The glu ligands are bis-(bidentate) bridges in 1 and bis-(monodentate) bridges in 2. The luminescence of 1 and thermal stability of 1 and 2 were investigated.     

Syntheses and structures of two copper coordination polymers with bis (1,2,4-triazol-1-ylmethyl)benzene and benzenedicarboxylate

Two copper coordination polymers [Cu(obtz)(bdc)] _n (1) and {[Cu(obtz)(phth)] · 2H₂O} _n (2) (obtz = 1,2-bis(1,2,4-triazol-1-ylmethyl)benzene, bdc = 1,3-benzenedicarboxylate, phth = 1,4-benzenedicarboxylate) were synthesized and characterized. Both 1 and 2 are 2-D networks constructed via the bridging ligands bdc and phth. The obtz ligands do not extend the dimension (2-D network) but add their thickness, 10.9 Å for 1 and 11.6 Å for 2. Complex 1 further constructs a 3-D network via π?π stacking interactions between the benzene rings of obtz ligands of adjacent 2-D networks. The thermal stabilities have been investigated.     

Construction of zinc–organic frameworks by flexible aliphatic dicarboxylates plus 2-(1H-imidazolyl-1-methyl)-1H-benzimidazole ligand

Three new Zn(II) complexes, [Zn(ox)(imb)] (1), [Zn₂(mal)₂(imb)₂] (2), and [Zn(suc)(imb)]·H₂O (3) (imb = 2-(1H-imidazolyl-1-methyl)-1H-benzimidazole, H₂ox = oxalic acid, H₂mal = malonic acid, H₂suc = succinic acid), have been synthesized and structurally characterized. Complex 1 is a 3-D framework with a 4-connected diamond topology with the topological notation of 6⁶. Complex 2 exhibits 2-D layers with (6,3) networks. Complex 3 displays a 3-D framework constructed through unusual 2-D → 3-D parallel interpenetration of corrugated 2-D (6,3) networks. IR spectra, PXRD patterns, thermogravimetric curves, and photoluminescence spectra are addressed.     

Framework engineering by anions and porous functionalities of Cu(II)/4,4'-bpy coordination polymers

A combination of framework-builder (Cu(II) ion and 4,4'-bipyridine (4,4'-bpy) ligand) and framework-regulator (AF(6) type anions; A = Si, Ge, and P) provides a series of novel porous coordination polymers. The highly porous coordination polymers ([Cu(AF(6))(4,4'-bpy)(2)].8H(2)O)(n)(A = Si (1a.8H(2)O), Ge (2a.8H(2)O)) afford robust 3-dimensional (3-D), microporous networks (3-D Regular Grid) by using AF(6)(2-) anions. The channel size of these complexes is ca. 8 x 8 A(2) along the c-axis and 6 x 2 A(2) along the a- or b-axes. When compounds 1a.8H(2)O or 2a.8H(2)O were immersed in water, a conversion of 3-D networks (1a.8H(2)O or 2a.8H(2)O) to interpenetrated networks ([Cu(4,4'-bpy)(2)(H(2)O)(2)].AF(6))(n)(A = Si (1b) and Ge (2b)) (2-D Interpenetration) took place. This 2-D interpenetrated network 1b shows unique dynamic anion-exchange properties, which accompany drastic structural conversions. When a PF(6)(-) monoanion instead of AF(6)(2)(-) dianions was used as the framework-regulator with another co-counteranion (coexistent anions), porous coordination polymers with various types of frameworks, ([Cu(2)(4,4'-bpy)(5)(H(2)O)(4)].anions.2H(2)O.4EtOH)(n)(anions = 4PF(6)(-) (3.2H(2)O.4EtOH), 2PF(6)(-) + 2ClO(4)(-) (4.2H(2)O.4EtOH)) (2-D Double-Layer), ([Cu(2)(PF(6))(NO(3))(4,4'-bpy)(4)].2PF(6).2H(2)O)(n)(5.2PF(6).2H(2)O) (3-D Undulated Grid), ([Cu(PF(6))(4,4'-bpy)(2)(MeCN)].PF(6).2MeCN)(n)(6.2MeCN) (2-D Grid), and ([Cu(4,4'-bpy)(2)(H(2)O)(2)].PF(6).BF(4))(n) (7) (2-D Grid), were obtained, where the three modes of PF(6)(-) anions are observed. 5.2PF(6).2H(2)O has rare PF(6)(-) bridges. The PF(6)(-) and NO(3)(-) monoanions alternately link to the Cu(II) centers in the undulated 2-D sheets of [Cu(4,4'-bpy)(2)](n)() to form a 3-D porous network. The free PF(6)(-) anions are included in the channels. 6.2MeCN affords both free and terminal-bridged PF(6)(-) anions. 3.2H(2)O.4EtOH, 4.2H(2)O.4EtOH, and 7 bear free PF(6)(-) anions. All of the anions in 3.2H(2)O.4EtOH and 4.2H(2)O.4EtOH are freely located in the channels constructed from a host network. Interestingly, these Cu(II) frameworks are rationally controlled by counteranions and selectively converted to other frameworks.     

Heterogeneous nanostructured electrode materials for electrochemical energy storage

In order to fulfil the future requirements of electrochemical energy storage, such as high energy density at high power demands, heterogeneous nanostructured materials are currently studied as promising electrode materials due to their synergic properties, which arise from integrating multi-nanocomponents, each tailored to address a different demand (e.g., high energy density, high conductivity, and excellent mechanical stability). In this article, we discuss these heterogeneous nanomaterials based on their structural complexity: zero-dimensional (0-D) (e.g. core-shell nanoparticles), one-dimensional (1-D) (e.g. coaxial nanowires), two-dimensional (2-D) (e.g. graphene based composites), three-dimensional (3-D) (e.g. mesoporous carbon based composites) and the even more complex hierarchical 3-D nanostructured networks. This review tends to focus more on ordered arrays of 1-D heterogeneous nanomaterials due to their unique merits. Examples of different types of structures are listed and their advantages and disadvantages are compared. Finally a future 3-D heterogeneous nanostructure is proposed, which may set a goal toward developing ideal nano-architectured electrodes for future electrochemical energy storage devices.     

Two lanthanide luminescent coordination compounds based on 3,5-pyrazoledicarboxylate and oxalic acid

Two isostructural 3-D complexes [Ln(pdc)(ox)_0.5(H₂O)₂]?H₂O (Ln = Tb(1), Eu(2); pdc = 3,5-pyrazoledicarboxylate; ox = oxalate) have been synthesized under hydrothermal conditions. Both are characterized by single crystal X-ray diffraction, elemental analysis, and IR. Compounds 1 and 2 possess a 3-D framework with 1-D rectangular channels built from 2-D, brick-like networks, and pdc ligands. The photoluminescence and lifetimes of 1 and 2 in the solid state have been studied.     

1-D cobalt(II) spin transition compound with strong interchain interaction: [Co(pyterpy)Cl(2)].X

Cobalt(II) compounds [Co(pyterpy)Cl(2)].MeOH (1.(MeOH)) and [Co(pyterpy)Cl(2)].2H(2)O (1.(2H(2)O)) were synthesized. The compound 1.(MeOH) forms the quasi 3-D networks by making pi-pi stacking between the 1-D chains. The methanol molecules from 1.(MeOH) can be removed by heating, and substituted by absorption of water molecules. The MeOH molecules in 1.(MeOH) are removed by heating at 410 K, and they are substituted by water molecules to form 1.(2H(2)O). 1.(2H(2)O) exhibits a S = (3)/(2) (HS) left arrow over right arrow S = (1)/(2) (LS) spin transition with a thermal hysteresis. We have succeeded in constructing a guest dependent 1-D spin-crossover cobalt(II) compound.     

Design of 3-D coordination networks: topology and metrics

Using 4,4',4"-tricyanotriphenylmethanol 1 as a heterotetradentate tecton with C3v symmetry bearing three CN and one OH group, under self-assembly conditions a 3-D coordination network was obtained in the presence of Ag+ cations acting as a tetrahedral metallic tecton; due to the metrics of 1 (three long and one short distance between the central C atom and N and O coordination sites, respectively), the 3-D network is of pseudo-diamondoid type with different cavity sizes; although a two-fold homo-interpenetration is observed for the 3-D networks, the remaining space is occupied by CHCl3, MeOH solvent molecules and SbF6- anions.     

Second sphere supramolecular chirality: racemic hybrid H-bonded 2-D molecular networks

Neutral hybrid 2-D networks have been generated using a bis-amidinium capable of chelating M(CN)6(3-) anions via hydrogen bonds: the packing of the achiral 2-D networks leads to channels which are occupied by water molecules forming polymeric H-bonded chains; furthermore, owing to the dihapto mode of H-bonding, the presence of supramolecular chirality of the delta' and lambda' types taking place within the second coordination sphere of the metallic centre has been demonstrated.     

Crystallography and magnetism of radicals with hindered hydroxyl groups: 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl and 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl

Radicals form networks of OH...ON and OH...Me(nitroxide) interactions. In 2, a frustrated network forms with insufficient N-O units to form extended chain interactions. The magnetism of 1 fits a 1-D Heisenberg model with J/k=-25 J mol(-1), while 2 shows more complex exchange behaviour consistent with its disordered crystal lattice.     

Self-assembly of two- and three-dimensional coordination networks with hexamethylenetetramine and different silver(I) salts

Interesting two-dimensional networks with square or hexagonal cavities, and three-dimensional networks with different channels, have been obtained by varying the counterions, the molar ratio of metal to hmt (hmt = hexamethylenetetramine) and the pH values of the initial solutions. Among the eleven products isolated and structurally characterized, two have a metal-to-hmt molar ratio of 2:1 and are the first examples of Ag-hmt square networks, namely [Ag2(mu4-hmt)(NO2)2] (1) and [Ag2(mu4-hmt)(SO4)(H2O)].4H2O (2), two have a metal-to-hmt molar ratio of 1:1 and are 2-D networks with hexagonal cavities, namely [Ag(micro3-hmt)(NO2)] (3) and [Ag2(micro3-hmt)2](S2O6).2H2O (4), and seven present the metal-to-hmt molar ratios of 3:1, 2:1, 3:2, or 4:3 and are 3-D networks of novel topologies and with different channels, namely [Ag2(mu4-hmt)(micro4-ox)] (5), [Ag3(micro4-hmt)2(H2O)2](SO4)(HSO4). 2H2O (6), [Ag2(mu4-hmt)(mu2-O2CMe)](MeCO2).4.5 H2O (7), [Ag2(mu4-hmt)(mu3-maleate)].5H2O (8), [Ag3(mu4-hmt)(mu2-O2CPh)3] (9), [Ag4(mu4-hmt)3(H2O)](SO4)(NO3)2.3H2O (10), and [Ag12(mu4-hmt)6(mu3-HPO4)(mu2-H2PO4)3(H2PO4)7(H2O)](H3PO4).10.5H2O (11).     

Synthesis,crystal structure,and characterization of two lanthanide coordination polymers based on isonicotinate ligand

Two new europium complexes [Eu(inic)₃(H₂O)] (1) and [Eu(inic)₃] (2) [inic = isonicotinate] have been structurally determined by single-crystal X-ray diffraction and characterized by elemental analysis, infrared spectroscopy, fluorescence, and thermogravimetric analysis. In the two complexes, bifunctional isonicotinate ligands interlink europium metal ions to construct 2-D (for 1) and 3-D (for 2) coordination polymeric networks.     

Structure of organic and metal-organic networks based on a bifunctional m-terphenyl carboxylic acid

A series of metal-organic frameworks (MOFs) based upon the ligand 2,6-diphenyl-1,4-dibenzoic acid [Ph2C6H2(CO2H)2]infinity have been prepared and characterized by X-ray crystallography. The networks exhibit a variety of topologies and coordination modes at the metal center. The reaction of the ligand with cobalt(II) nitrate or zinc(II) nitrate in methanol/pyridine results in the formation of isostructural 1-D chains [(Ph2C6H2(CO2)2)M(py)2(MeOH)]infinity, where M = Zn, Co; however, in the presence of ethanol and triethylamine, Zn(NO3)2 reacts to form a 2-D clay-like network, [(Ph2C6H2(CO2)2)Zn(EtOH)2]infinity. 2-D networks are also formed in similar reactions with copper(II) nitrate or silver(I) nitrate to give [(Ph2C6H2(CO2)(CO2H))2Cu(py)2]infinity, [(Ph2C6H2(CO2)CO2H))2Cu(py)4.2H2O](infinity), and [(Ph2C6H2(CO2)2)Ag2]infinity, respectively. The hydrogen-bonded chains formed by the ligand alone and with 4,4'-dipyridyl are also described.