Search

An understanding of the atomic-scale interactions between gas sorbent materials and their molecular guests is essential for the identification of the origins of desirable function and the rational optimization of performance. However, characterizations performed on equilibrated sorbent-guest systems may not accurately represent their behavior under dynamic operating conditions. The emergence of fast (minute-scale) neutron powder diffraction coupled with direct, real-time quantification of gas uptake opens up new possibilities for obtaining knowledge about concentration-dependent effects of guest loading upon function-critical features of sorbent materials, including atomic structure, diffusion pathways, and thermal expansion of the sorbent framework. This article presents a detailed investigation of the ultramicroporous metal-organic framework [Cu3 (cdm)4 ] as a case study to demonstrate the variety of insights into sorbent performance that can be obtained from real-time characterizations using neutron diffraction.

The interdependent effects of temperature and guest uptake on the structure of the ultramicroporous metal-organic framework [Cu3 (cdm)4 ] (cdm=C(CN)2 (CONH2 )- ) were explored in detail by using in situ neutron scattering and density functional theory calculations. The tetragonal lattice displays an anisotropic thermal response related to a hinged "lattice-fence" mechanism, unusual for this topology, which is facilitated by pivoting of the rigid cdm anion about the Cu nodes. Calculated pore-size metrics clearly illustrate the potential for temperature-mediated adsorption in ultramicroporous frameworks due to thermal fluctuations of the pore diameter near the value of the target guest kinetic diameter, though in [Cu3 (cdm)4 ] this is counteracted by a competing contraction of the pore with increasing temperature as a result of the anisotropic lattice response.

Two unusual isostructural nanocage-based 3D Ln-MOFs, 1-Ln (Ln = Tb and Eu), were constructed using a new diisophthalate ligand with active Lewis basic triazole sites. 1-Eu exhibits highly efficient luminescent sensing for Fe3+ cations and Cr2O72- anions, and selective CO2 capture over CH4.

A new ZnII metal-organic framework, [Zn6 (L)3 (DMA)4 ]⋅5 DMA (H4 L=[1,1':3',1''-terphenyl]-3,3'',5,5''-tetracarboxylic acid, DMA=dimethylacetamide), has been synthesized and characterized. The structure contains a three-dimensional 3,4,4,6-connected net with (4.62 )2 (66 )(66 )(42 .610 .83 ) topology and displays selective detection of nitrobenzene, CrO42- and Fe3+ ions. The present work thus indicates that this metal-organic framework could be a prospective candidate for developing novel luminescence sensors for the selective sensing of nitrobenzene, which can be used as a precursor for explosives. Furthermore, the photoluminescent properties of this material in different solvents and with various analytes were investigated and corroborated by theoretical calculations. The results were in good agreement with the experimental solvent-dependent luminescence behavior.

A series of soluble metal ethylxanthate compounds was synthesised as precursors for metal sulfide thin films to be deposited using solution-based techniques. Initially, a range of air- and moisture-stable organic ethylxanthate (EtXn) salts were synthesised (cation=Me4N (1), Et4N (2), Pr4N (3), Ph4P (4), guanidinium (5), NMeH3 (6), NMe2H2 (7), NMe3H (8), NH4 (9)). Thermogravimetric analysis (TGA) was used to examine their decomposition profiles, which in turn informed the decision of which counter cation was best suited for inclusion in the metal xanthate compounds. Periodic NMR spectroscopy studies and single-crystal X-ray diffraction (SXRD) were used to determine the role protic ammonium counter cations play in the detrimental conversion of xanthates to dithiocarbamate anions. The organic salts 1 and 4 were used to form the metal ethylxanthate compounds (Me4N)[M(EtXn)x] (x=3 for M=Cd (10 Cd), Ni (10 Ni), Zn (10 Zn); x=4 for M=La (11 La)) and (Ph4P)[M(EtXn)3] (M=Cd (12 Cd), Ni (12 Ni), Zn (12 Zn)). Solubility studies on these compounds were performed using a range of solvents to demonstrate the viability of using these compounds for solution-based deposition methods for thin-film formation. TGA of the metal xanthate compounds was used to examine their thermal-decomposition profiles and the product resulting from thermolysis was found to be the respective metal sulfide. In addition, the coproducts of thermal decomposition were analysed by headspace gas-chromatography mass spectrometry (HS GC–MS) to probe the decomposition mechanism of the precursors. In situ variable-temperature synchrotron XRD studies on both bulk and thin-film samples of 10 Cd and 12 Cd were used to examine metal sulfide crystalline phase formation. Decomposition of both precursors was found to give CdS in a hexagonal phase, with the addition of CdCl2 found to aid in increasing the crystallite size during crystallisation.

The evaluation of a new azacrown ether ligand bis{[3-(pyridin-4-yl)-1H-pyrazol-1-yl]methyl}diaza-18-crown-6 (b3pd), which contains pendant p-pyridylpyrazole arms connected by diaminomethane linkers, identified a tendency to undergo retro-Mannich fragmentation in the presence of transition-metal ions. However, treatment of b3pd with potassium perchlorate or potassium iodide prior to complexation with transition-metal ions imparted a resistance to fragmentation, such that crystallisation of coordination polymers from concentrated solutions after several weeks was possible. Four solid-state structures containing Kb3pd were isolated: a perchlorate salt (1), a divalent manganese 1D coordination polymer [Mn(Kb3pd)(DMF)4]·2ClO4·I3 (2, DMF = N,N-dimethylformamide), a cuprous 2D coordination network [Cu2(Kb3pd)2(I3)(I)3]·3H2O (3) and a cuprous 1D coordination polymer [Cu(Kb3pd)(I)2] (4). Additionally, the retro-Mannich process was investigated by in situ FTIR spectroscopy, mass spectrometry, crystallography and by the isolation of a cobalt complex ligated by a partially fragmented ligand, mono{[3-(pyridin-4-yl)-1H-pyrazol-1-yl]methyl}diaza-18-crown-6 (m3pd). The composition of the cobalt complex was found to be [CoCl3(Hm3pd)]·H2O (5).

From a predesigned grid, [Cu(II)5Cu(I)4L6]⋅(I)2⋅13 H2O (1), in which LH2 was a pyrazinyl-triazolyl-2,6-substituted pyridine, we successfully synthesized an extended 3D complex, (1)∞[{Cu(II)5Cu(I)8L6}{μ-[Cu(I)3(CN)6]}2⋅2 CH3-CN] (2), that displayed unprecedented coexistence of all the five known coordination geometries of copper. Grid 1 displayed monovalent central metal exchange (CME) of Cu(I) for Ag(I) for the first time, as well as the formation of tri-iodide in the crystalline state. These systems were investigated for their magnetic properties. Remarkably, grid 1 showed much higher catalytic activity than the Ag-exchanged product for synthesis of a substituted triazole, 1-benzyl-4-phenyl-1H-1,2,3-triazole.

A new family of organic ionic materials of the dicyano(nitroso)methanide anion is reported. Six of the compounds are room-temperature ionic liquids with low viscosities, which is a physical property highly desired for many synthetic and electrochemical applications. In addition, use of dimethylpyrrolidinium and tetramethylammonium cations yield the first reported dicyano(nitroso)methanide organic ionic plastic crystals, which have an advantageously wide plastic phase region. The salts also exhibit good conductivities and thermal stabilities thus making them suitable as liquid or solid-state electrolytes for a range of electrochemical devices.

A series of low-melting-point salts with hexakisdicyanonitrosomethanidolanthanoidate anions has been synthesised and characterised: (C(2) mim)(3) [Ln(dcnm)(6)] (1 Ln; 1 Ln=1 La, 1 Ce, 1 Pr, 1 Nd), (C(2) C(1) mim)(3) [Pr(dcnm)(6)] (2 Pr), (C(4) C(1) pyr)(3) [Ce(dcnm)(6)] (3 Ce), (N(1114))(3) [Ln(dcnm)(6)] (4 Ln; 4 Ln=4 La, 4 Ce, 4 Pr, 4 Nd, 4 Sm, 4 Gd), and (N(1112OH) )(3) [Ce(dcnm)(6)] (5 Ce) (C(2) mim=1-ethyl-3-methylimidazolium, C(2) C(1) mim=1-ethyl-2,3-dimethylimidazolium, C(4) C(1) py=N-butyl-4-methylpyridinium, N(1114) =butyltrimethylammonium, N(1112OH) =2-(hydroxyethyl)trimethylammonium=choline). X-ray crystallography was used to determine the structures of complexes 1 La, 2 Pr, and 5 Ce, all of which contain [Ln(dcnm)(6)](3-) ions. Complexes 1 Ln and 2 Pr were all ionic liquids (ILs), with complex 3 Ce melting at 38.1 °C, the lowest melting point of any known complex containing the [Ln(dcnm)(6)](3-) trianion. The ammonium-based cations proved to be less suitable for forming ILs, with complexes 4 Sm and 4 Gd being the only salts with the N(1114) cation to have melting points below 100 °C. The choline-containing complex 5 Ce did not melt up to 160 °C, with the increase in melting point possibly being due to extensive hydrogen bonding, which could be inferred from the crystal structure of the complex.

International audience; A series of 1D polymeric FeII spin crossover (SCO) compounds of type trans-[FeII(NCX)2(L)]·Solvent has been synthesised {L = DPPyT = 1-[4,6-bis(dipyridin-2-ylamino)-1,3,5-triazin-2-yl]pyridin-4(1H)-one for 1–4; NCX = NCS– for 1 and 2, NCSe– for 3 and 4; Solvent = 2.5CH2Cl2 for 1, 2CHCl3·0.5CH3OH for 2 and 4, CH2Cl2 for 3; L = DPT (6-phenoxy-N2,N2,N4,N4-tetra-2-pyridinyl-1,3,5-triazine-2,4-diamine) for 5; NCX = NCS– for 5; Solvent = 2CH3OH·H2O for 5; L = DQT {4-[4,6-bis(dipyridin-2-ylamino)-1,3,5-triazin-2-yloxy]phenol} for 6–8; NCX– = NCS– for 6; Solvent = 2CH2Cl2 for 6; NCX– = NCSe– for 7; Solvent = CH2Cl2·CH2ClCH2Cl for 7; NCX– = NCSe– for 8; Solvent = 1.5CH2Cl2·0.5CH3OH for 8}. Two mononuclear complexes, trans-[FeII(NCS)2(DPT)2]·2CH3OH (9) and trans-[FeII(NCSe)2(DPT)2]·2CH3OH (10), contained the L ligand in a terminal bidentate coordination mode. As well as variations made in the NCX– ligands, variations were also made in substituent groups on the s-triazine “core” of L to investigate their intermolecular/supramolecular role in crystal packing and, thus, their influence on SCO properties. All the complexes crystallised as solvates, and the influence of the latter on the magnetism and spin transitions was explored. A wide range of physical methods was employed, as a function of temperature, viz. crystallography, PXRD (synchrotron), susceptibilities, LIESST and Mössbauer effect, in order to probe magnetostructural correlations in these 1D families. New examples of half-crossovers, with ordered –LS–HS–LS–HS– intrachain states existing below T1/2, have been observed and comparisons made to related one- or two-step systems. All the observed transitions are gradual and non-hysteretic, and brief comments are made in relation to recent theoretical models for cooperativity, developed elsewhere.

The anionic dinitrile ligand dicyanonitrosomethanide (dcnm), C(CN) 2 (NO) - , and the anion resulting from its addition product with water, carbamoylcyanonitrosomethanide (ccnm), C(CN)(CONH 2 )(NO) - , have been incorporated into lanthanoid complexes and display unusual η 2 (N,O) nitroso coordination modes. (Et 4 N) 3 [Ln(ccnm) 6 ] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm) and (Me 4 N) 3 [Ln(ccnm) 6 ] (2Ln; 2Ln = 2La, 2Ce, 2Pr, 2Nd) are systems containing 12-coordinate homoleptic trianionic lanthanoidate complexes. The nitroso groups of the ccnm ligands form three-membered ring chelates with the lanthanoid metal centre, with the asymmetry of the nitroso η 2 interactions dependent upon the intramolecular N-H ··· O=N hydrogen bonding. Additional intermolecular hydrogen bonding interactions exist between adjacent amide and nitrile groups giving rise to 3D α-Po and 6,8-connected (4 12 .6 3 )(4 20 .6 8 ) networks in 1Ln and 2Ln, respectively. The compounds (Me 4 N) 3 [Ln(dcnm) 6 ] (3Ln; 3Ln = 3La, 3Ce, 3Nd, 3Sm) also contain a 12-coordinate trianionic lanthanoidate complex with the nitroso group exhibiting a highly symmetrical η 2 interaction. The sterically crowded environments of [Ln(18-crown-6)(dcnm) 3 ] (4Ln; 4Ln = 4La, 4Ce, 4Pr, 4Nd) result in a shift towards a more asymmetric η 2 bonding of the nitroso group with decrease in the Ln 3+ radius. There is a corresponding increase of the Ln-O-N angle, and one ligand is η 1 (O) binding in 4Nd. The dcnm ligands in the discrete complexes [La(phen) 3 (dcnm) (3-x) Cl x ], x ≈ 0.25 (5) (phen = 1,10-phenanthroline), (Et 4 N)[Ce(phen) 2 (dcnm) 4 ] (6a/ b, 6c) and [Ce(phen) 2 (dcnm)Cl 2 H 2 O] (7) display a variety of coordination modes. Complex 5 has 1D chains formed by π-π stacking of adjacent phen co-ligands. Complexes 6 contain the monoanionic complex [Ce(phen) 2 (dcnm) 4 ] - with two geometric isomers present in the crystal structure of 6a/b. Complex 7 forms extended 1D chains via hydrogen bonding between coordinated water and chloride atoms and an extensive array of face-to-face π interactions.

Ligands resulting from the transition-metal-promoted nucleophilic addition of water or an alcohol to dicyanonitrosomethanide ions (dcnm) have been utilised in the formation of a large series of polynuclear complexes. Addition of water to dcnm results in formation of carbamoylcyanonitrosomethanide (ccnm); deprotonation of this ligand gives amidocarbonyl(cyano)nitrosomethanide (acnm), which has been incorporated into the trinuclear complex [Cu 3 (acnm) 2 (dmae) 2 (H 2 O) 2 ] [dmae = 2-(dimethylamino)ethoxide] (1) which shows strong antiferromagnetic coupling with an exchange coupling constant, J = ―500 cm ―1 . [Cu(acnm)(NH 3 ) 2 ] ∞ (2) marks the first instance of acnm facilitating the formation of a coordination polymer, namely a 1D chain with intramolecular hydrogen bonding. Attempts to synthesise 2 through different reaction conditions instead resulted in the mononuclear [Cu(acnm)-(NH 3 ) 2 (py)] (py = pyridine) (3). The addition of ethanol to dcnm results in cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) which features in the mononuclear [Cu(cenm) 2 -(H 2 O) 2 ] (4) and polymeric {[Cu(cenm) 2 ] 2 ·H 2 O} ∞ (5). The latter is the first example of the cenm ligand in a coordination polymer and has a highly unusual coordination mode through the nitrile groups and extremely weak antiferromagnetic coupling. {[Mn 3 (ccnm) 2 (EtOH) 2 (OAc) 4 ]·2EtOH} ∞ (6) and (Et 4 N) 2 -[Cu(ccnm) 4] (7) contain previously unobserved coordination modes of the ccnm ligand while the complex [Mn(cmnm) 3 -Mn(bipy)(MeOH)](ClO 4 ) (8) {cmnm=cyano[imino(methoxy)-methyl]nitrosomethanide, bipy = 2,2'-bipyridine} displays weak antiferromagnetic coupling between manganese atoms with J = ―1.44 cm ―1 . A change in the solvent systems used in the synthesis of 7 results in the formation of the mononuclear complexes [Mn(bipy) 2 (dcnm) 2 ] (9) or [Mn(bipy) 2 (H 2 O)-(dcnm)](dcnm)·H 2 O (10) and [Mn(bipy) 2 (dcnm)(H 2 0)](dcnm) (11). The addition of ethlyene glycol monomethyl ether to dcnm gives cyano[imino(2-methoxyethoxy)methyl]nitrosomethanide (cgnm) and the formation of [Cu(cgnm) 2 -(H 2 O) 2 ] (12).

The synthesis and structure of the hydrated mono- and di-potassium salts of benzenepentacarboxylic acid are reported (K(H4BPC)(H2O)2 )·( H2O) 1 and (K2(H3BPC)(H2O)3 )·( H2O) 2 (BPC benzenepentacarboxylate). In both instances the structures are complex coordination networks, predominantly containing η 1

A series of interesting coordination polymers have been prepared by the combination of a V-shaped 4,4′-oxybis(benzoic acid) (H2oba) and neutral organonitrogen ligands with different metal ions, namely, {[M(oba)(bpe)]·H2O}n [M = Mn (1), Co (2)], [M(oba)(N3)]n [N3 = dipyridin-2-ylamine; M = Cd (3), Cu (4)] and {[Zn(oba)(N5)]·2H2O}n (5) [bpe = 1,2-bis(4-pyridyl)ethene, N5 = bis(pyridin-2-yl)pyridine-2,6-diamine]. The framework structures of these neutral polymeric complexes have been determined by single-crystal X-ray diffraction studies. Compound 1 has a threefold pcu-type network structure. Although 2 has the same ligands and coordination modes as 1, it consists of corrugated 2D layers formed of a series of squares, which allows the sheets to interpenetrate in an unusual 2D 3D parallel fashion. Polymers 3 and 4 exhibit double-helical chains formed by π–π stacking interactions from the phenyl rings of the N3 ligands. Compound 5 forms a 2D supramolecular architecture directed by hydrogen bonding between the NH groups of the N5 ligand, the uncoordinated carboxylate oxygens, and the intercalated water molecules. This work markedly indicates that the effect of auxiliary ligands is significant in the construction of these network structures, which are also well regulated by the metal centers. Thermogravimetric analysis (TGA) and XRPD results for compound 1 as well as luminescent properties for compounds 3 and 5 are discussed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Three lanthanide coordination polymers constructed from infinite rod-shaped secondary building units (SBUs), [Nd(2)(H(2)O)(2)(cis-chdc)(2)(trans-chdc)]2H(2)O (1), Nd(2)(H(2)O)(4)(trans-chdc)(3) (2), and [Sm(2)(H(2)O)(2)(cis-chdc)(trans-chdc)(2)]4H(2)O (3) (chdcH(2)=1,4-cyclohexanedicarboxylic acid), were hydrothermally synthesized and structurally characterized. The structures of 1-3 are modulated by different ratios of the cis and trans configurations of chdc(2-) ligands, which was achieved by temperature control in the hydrothermal reactions. Crystal-structure analysis revealed that 1 is a four-connected pcu-type rod packing network built from cross-linking of rod-shaped neodymium-oxygen SBUs by cis- and trans-chdc(2-) ligands in a 2:1 ratio, 2 displays a complicated six-connected hex-type rod packing structure built by connection of rod-shaped neodymium-oxygen SBUs and trans-chdc(2-) ligands, and 3 features an unprecedented five-connected rod packing pattern constructed from rod-shaped samarium-oxygen SBUs and cis- and trans-chdc(2-) ligands in a 1:2 ratio.

Three series of porous lanthanide metal-organic coordination polymers, namely [Cu(bpy)Ln(3)(ip)(5)(Hip)(H(2)O)] [Ln = Er (1a), Y (1b), Eu (1c); bpy = 2,2'-bipyridine, H(2)ip=isophthalic acid], [Cu(3)(bpy)(2)Ln(2)(ip)(6)(H(2)O)(5)] [Ln = Yb (2a), Gd (2b), Tb (2c)], and [Cu(3)Ln(2)(ip)(6)] [Ln = Eu (3a), Gd (3b)] have been synthesized hydrothermally by the reaction of the combination of 3d-4f metal centers and N-/O-donor ligands. X-ray diffraction analyses reveal that polymers 1a-c and 2a-c, as well as 3a, b are isomorphous in structure. Polymers 1a-c consist of 3D alpha-Po networks based on a inorganic rod-shaped secondary building units (SBUs) of {Er(6)Cu(2)(bipy)(2)(O(2)C)(11)} which are 27.03 A in length. Polymers 2a-c also contain 3D alpha-Po networks, constructed from shorter (14.79 A) but similarly rod-shaped SBUs of {Yb(2)Cu(3)(bpy)(2)(O(2)C)(12)}. The structure also contains hydrogen-bonded (H(2)O)(6) chains which can be reversibly dehydrated/rehydrated. Polymers 3a, b contain metal carboxylate substructures which have 2D (6,3) topologies; these layers are bridged by the ip(2-) ligands to give an overall 3D network which contains two sorts of cavities. This series of Ln-Cu coordination polymers are further characterized by antiferromagnetic behavior.

A novel T4(1) water chain in a new CuII coordination polymer, {[Cu(C4H6N2)2(C4H2O4)] (H2O)3}n (1, where C4H6N2 = 2-methylimidazole, C4H2O4 = maleate), has been synthesized and structurally characterized by single-crystal X-ray diffraction. Thermogravimetry, infrared spectroscopy, elemental analysis, and magnetic analysis have also been used to characterize 1. Complex 1 crystallizes in the trigonal space group P3221, and the 1-D chains composed of cyclic water tetramers play an important role in stabilizing the overall polymeric structure. Furthermore, this 1-D water chain presents an unusual association mode of water molecules.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

To systematically explore the higher-dimensional network structures with mixed connectivity, a series of two-dimensional (2D) and three-dimensional (3D) metal-organic frameworks (MOFs) with unusual (3,6)-connected net topologies are presented. These crystalline materials include [{[Mn(btza)2(H2O)2].2 H2O}n] (1), [{[Zn(btza)2(H2O)2].2 H2O}n] (2), [{[Cu(btza)2].H2O}n] (3), and [{[Cd(btza)2].3 H2O}n] (4), which have been successfully assembled through a predesigned three-connected organic component bis(1,2,4-triazol-1-yl)acetate (btza) with a variety of octahedral metal cores based on the modular synthetic methodology. The topological paradigms shown in this work cover the 2D CdCl2, 3D (4(2).6)2(4(4).6(2).8(7).10(2)), and pyrite (pyr) types. That is, when properly treated with the familiar first-row divalent metal ions, btza may perfectly furnish the coordination spheres for effective connectivity to result in diverse (3,6)-connected nets. Beyond this, a detailed analysis of network topology for all known 3D (3,6)-connected frameworks in both inorganic and inorganic-organic hybrid materials is described. Specific network connectivity of these MOFs indicates that the metal centers represent the most significant and alterable factor in structural assembly, although they show reliable and similar geometries. In this context, the combination of the distinct d10 AgI ion with btza in different solvents affords two isomorphous MOFs [{[Ag(btza)].glycol}n] (5) and [{[Ag(btza)]CH3OH}n] (6) with a binodal 4-connected 3D SrAl2 (sra) topology. The network structures of MOFs 1-3 and 5 turn out to be more complicated and interesting if one considers the hydrogen bonding between the host coordination frameworks and the intercalated solvent molecules. Furthermore, the role of the included solvents in the generation and stabilization of MOFs 1-6 is also investigated.

The construction of coordination networks with novel topologies and porous structures that provide new sizes, shapes, and chemical environments is of great interest in recent years, due to their intriguing structural diversity and potential for many applications. 2] In recent years many porous metal– organic frameworks with unique structures have been obtained and their adsorption properties were widely investigated, however, those with specially shaped channels such as 1D helices are rare. Metal–ligand coordination has been well used in the directed assembly of extended porous metal–organic networks, and one of the key points for such studies is the design or choice of components that organize themselves into desired patterns with useful functions. In this regard, considerable attention has been devoted to the networking ability of isonicotinic acid (1) and its derivatives, which are multifunctional ligands potentially able to act as bridging ligands to produce open lattice species with various structural topologies and large pores. In this study, we choose an analogy of 1, 9-acridinecarboxylic acid (HL), whose coordination chemistry has not been previously investigated, as a bridging ligand to construct new framework materials with novel structures and special properties based on combining its bridging coordination ability with its steric bulk. Although the coordination sites of HL and 1 are very similar, their coordination chemistry are found to be quite different due to the bulk of HL. We report herein a 3D twofold interpenetrating NbO-type network [Cu2(m2OMe)2(L)2·(H2O)0.69]n (2) with 1D channels.

Spotlight on coordination polymers: ChemPlusChem is pleased to present its special issue on coordination polymers/metal-organic frameworks (MOFs), guest-edited by Stuart Batten, Banglin Chen and Jagadese J. Vittal. This issue features MOFs through various applications as sensors and in drug delivery, gas storage, catalysis etc.

Small cyano anions, and their derivatives, have proved to be remarkably versatile building blocks for coordination polymers. They have led to magnetically ordered materials, structures with new entangled motifs or novel topologies, and a significant structural diversity, including polymorphism, induced by subtle changes in anion, cation, co-ligands, preparative conditions, or even desolvation.

The three-dimensional coordination polymers [Mn(dca)2(H2O)] (1) and [M(dca)(tcm)], M =Co (2), Ni (3), Cu (4), dca =dicyanamide, N(CN)2-, tcm = tricyanomethanide, C(CN)3-, have isomorphous structures. In 1 half the dca ligands coordinate directly (through all three nitrogen atoms) to three Mn atoms (all metal atoms are six-coordinate), while the other half coordinate to two Mn atoms (through the nitrile nitrogens) and hydrogen bond to water molecules coordinated to a third Mn atom (through the amide nitrogen). This dca. H2O structural moiety is disordered over a mirror plane, and is replaced by the structurally equivalent tcm ligand in compounds 2-4. The resulting structures display a new self-penetrating 3,6-connected (2:1) network topology that can be related to, but is different from, the rutile net. The self-penetrating [M(dca)(tcm)] network can be viewed as a structural compromise between the two interpenetrating rutile-like networks of [M(tcm)2] and the single rutile-like network of alpha-[M(dca)2]. The temperature and field dependence of the DC and AC magnetic susceptibilities and magnetisations has been measured for complexes 1-4. Compounds 1-3 exhibit long-range magnetic order with critical temperatures of 6.3 K for 1, 3.5 K for 2 and 8.0 K for 3. The Cu11 compound 4 does not order and is essentially a paramagnet. Hysteresis measurements of coercive field and remnant magnetisation show that 1, 2 and 3 are soft magnets, 1 being a canted-spin antiferromagnet (weak ferromagnet), while 2 and 3 are ferromagnets that display some unusual features in their high-field magnetisation isotherms in comparison to their related alpha-[M(dca)2] phases.

Reaction of Cu(I), tricyanomethanide (tcm , C(CN)3-) and L = either hexamethylenetetramine (hmt), 4,4'-bipyridine (bipy) or 1,2-bis(4-pyridyl)ethene (bpe) gives crystals of [Cu(tcm)(hmt)] (1), [Cu(tcm)(bipy)] (2) and [Cu(tcm)(bpe)] x 0.25 bpe x 0.5 MeCN (3), respectively. Crystal structure analysis shows 1-3 all contain closely related puckered (4,4) sheets composed of tetrahedral Cu(I) ions bridged by 2-connecting tcm- and L. The crystal packing, however, varies markedly with L. In 1 the sheets interdigitate in pairs. In 2 the sheets participate in parallel interpenetration in pairs. In 3 guest bpe and MeCN molecules are intercalated in channels formed by the stacking of the sheets.

Independent one-, two-, and even three-dimensional nets interpenetrate each other in many solid-state structures of polymeric, hydrogen-bonded nets and coordination polymers. For example, the interpenetration of the adamantane units of two diamondlike nets is shown on the right. A detailed and systematic examination of many interpenetrating nets of this kind is made, and implications for crystal engineering are discussed.

Unaufloslich ineinander verwoben sind in vielen Festkorperstrukturen von polymeren, uber H-Brucken gebundenen Netzen und von Koordinationspolymeren die als voneinander unabhangig betrachteten ein-, zwei- oder gar dreidimensionalen Netzstrukturen. Rechts ist z. B. die gegenseitige Durchdringung der Adamantaneinheiten zweier diamantartiger Netze gezeigt. Aus der detaillierten Beschreibung und Systematik der mehrfachen gegenseitigen Durchdringung von derartigen Netzen in Festkorperstrukturen lassen sich unter anderem weitreichende Folgerungen fur das Kristall-Engineering ableiten.

The thermal and light-induced magnetic properties of a family of discrete magnetically switchable 'nanoball' species (3 nm in diameter) is reported. The self-assembly of these materials is accomplished by the use of the metallo building block, [Cu([Tp{sup 4-py}])(NCCH{sub 3})] ([Tp{sup 4-py}]=tris-[3-(4{prime}-pyridyl)pyrazol-1-yl]hydroborate), combined with a [Fe(NCX){sub 2}] (X = S, Se and BH{sub 3}) species. We previously showed that the thiocyanate analogue (Fe(NCS)-nano) undergoes a thermal and light-induced spin crossover (SCO) - the largest such discrete SCO material reported. Now included in this family are the Se and BH{sub 3} analogues, Fe(NCSe)-nano and Fe(NCBH{sub 3})-nano, which show increased thermal transition temperatures (T{sub 1/2} = 124 K, 162 and 173 K). This variation in transition temperature over the series S < Se < BH{sub 3} results in diverse photomagnetic properties, such that the light-induced excited spin state trapping (LIESST) effect is exhibited to varying degrees and at different temperatures by the S, Se and BH{sub 3} analogues.

The chemistry of the anions dicyanamide and tricyanomethanide (dca and tcm, respectively) has produced a plethora of discoveries over the past few decades, particularly in relation to transition-metal coordination polymers with magnetic coupling. Over recent years there have been an increasing number of reports of heterofunctionalised cyano-containing anions, typically derivatives of dicyanomethanide. Our own group has been particularly concerned with the amide- and nitroso-functionalised anions carbamoyldicyanomethanide (cdm) and dicyanonitrosomethanide (dcnm), respectively. This feature article examines the fascinating diversity of materials and complexes that can be obtained using small cyano anions, ranging from coordination polymers to heterometallic clusters and hydrogen bonding networks. In particular, we focus on results from our own laboratories in the past few years. The magnetic properties of these materials are briefly discussed.

Independent one-, two-, and even three-dimensional nets interpenetrate each other in many solid-state structures of polymeric, hydrogen-bonded nets and coordination polymers. For example, the interpenetration of the adamantane units of two diamondlike nets is shown on the right. A detailed and systematic examination of many interpenetrating nets of this kind is made, and implications for crystal engineering are discussed.

The shortest circuits in the three-dimensional network with (12,3) topology of solvated Ni(tpt)(NO3 )2 pass through one another (see picture). This network based upon interlinked double helices occupies a unique position in the set of (n,3) nets. tpt=tri-4-pyridyl-1,3,5-triazine.

Hydrothermal reaction of diaminomaleonitrile and copper salts under different conditions resulted in copper cyanide coordination polymers {[Cu(H2O)(NH3)4][Cu3(CN)5]·H2O}n (1), {(CH3)4N[Cu(H2O)(NH3)4][Cu4(CN)7]}n (2), and {(CH3OH2)2[Cu2(CN)3]}n (3). 1 and 2 are new mixed-valence Cu(I,II), two 3D organic−inorganic molecular framework complexes that exhibit ionic inclusion. 3 is an open copper cyanide framework hosting a guest molecule. Cyanides in 1, 2, and 3 are produced by in situ C−C bond cleavage of diaminomaleonitrile, and then the remaining product is oxidized to form an oxalate group. The potential porosity of the hydrated coordination polymer 3 was estimated using a computational method based on Connolly’s algorithm.

Invited for this month’s cover is the collaboration between three different groups at Monash University, Deakin University and the ARC Centre of Excellence for Electromaterials Science. The cover picture shows a photograph of an organic ionic plastic crystal, and the structure of the anti and syn isomers of the ccnm anion. Read the full text of the article on page 486.