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Five Metal–Organic Frameworks ({[M2(tdc)2(L)2]·2DMF}, tdc = 2,5-thiophenedicarboxylate, M = ZnII (1–Zn), CuII (1–Cu), MnII (1–Mn), {[Zn(oba)(L)]·DMF·H2O} (2–Zn), oba = 4,4′-oxybisbenzoate, and {[Zn2(bpdc)2(L)2]·L}, (3–Zn) bpdc = 4,4′-biphenyldicarboxylate) that incorporate the redox-active 2,5-dipyridylthiazolo[5,4-d]thiazole (DPTzTz) ligand (L) have been synthesised and their electronic properties elucidated. The ligand-based organic radicals were generated using in situ techniques and monitored using a suite of solid-state spectroelectrochemistry techniques. The absence of a near infra-red band (NIR), indicating through-space intervalence charge transfer (IVCT), in all analysed materials suggests that both the inter-ligand distance between cofacial TzTz moieties and the flexibility of the TzTz moiety affect the through-space IVCT. [ABSTRACT FROM AUTHOR]

We highlight two key examples of where the achirality of reagents used in MOF syntheses transposes to chiral structures, thereby expanding the potential ligand pool used in the future design of chiral MOFs. Herein, we report the characterisation of two new chiral CdIIMOFs: (1) a pair of enantiomorphous structures produced from the achiral bicyclo[1.1.1]pentane-1,3-dicarboxyate linker, [Cd(pdc)(DMF)] (pdc = bicyclo[1.1.1]pentane-1,3-dicarboxylate; DMF = N,N-dimethylformamide) (3DL-MOF-3), and (2) a similar chiral network featuring cubane-1,4-dicarboxylate, [Cd3(cdc)3(DMF)3] (cdc = cubane-1,4-dicarboxylate) (3DL-MOF-4). Conventional solvothermal synthesis of 3DL-MOF-3 yields a conglomerate of two enantiomorphs that spontaneously resolve into their respective right- or left-handed chiral hexagonal space groups (space groups P61/P65). Similarly, 3DL-MOF-4 resolves into a non-centrosymmetric orthorhombic phase (P21212). Both 3DL-MOF-3 and 3DL-MOF-4 possess infinitely-linked, chiral, and 1D Cd-O helical chains which are observed to be the apparent cause of chirality in each system. In both cases, homochirality is preserved within each individual crystal where only one type of helical handedness is observed. We consider a general mechanism for this preservation of homochirality to include an avoidance of a physical analogue of geometric frustration which manifests due to the tripartite nature of the underlying triangular lattice upon which each chiral chain is located. [ABSTRACT FROM AUTHOR]

A 3D Hofmann-like metal–organic framework has been prepared which contains a 2,1,3-benzothiadiazole-based pillaring ligand. Encapsulation of a polycyclic aromatic hydrocarbon, chrysene, within the pore structure leads to a new pathway to multi-step spin crossover behaviour in which the observed two-step spin transition arises due to the presence of multiple site environments associated with local guest positional effects within the host lattice. [ABSTRACT FROM AUTHOR]

Inclusion of an angular bridging ligand, 4,2′:6′,4′′-terpyridine (TPy), into a Hofmann-type framework produces an irregular network in which six- and five-coordinate FeII species co-exist. The octahedral sites show thermally-induced spin-crossover (SCO) and the rare five-coordinate FeII sites are high-spin. [ABSTRACT FROM AUTHOR]

Electroactive metal–organic frameworks (MOFs) are an attractive class of materials owing to their multifunctional 3-dimensional structures, the properties of which can be modulated by changing the redox states of the components. In order to realise both fundamental and applied goals for these materials, a deeper understanding of the structure–function relationships that govern the charge transfer mechanisms is required. Chemical or electrochemical reduction of the framework [Zn(BPPFTzTz)(tdc)]·2DMF, hereafter denoted ZnFTzTz (where BPPFTzTz = 2,5-bis(3-fluoro-4-(pyridin-4-yl)phenyl)thiazolo[5,4-d]thiazole), generates mixed-valence states with optical signatures indicative of through-space intervalence charge transfer (IVCT) between the cofacially stacked ligands. Fluorination of the TzTz ligands influences the IVCT band parameters relative to the unsubstituted parent system, as revealed through Marcus–Hush theory analysis and single crystal UV-Vis spectroscopy. Using a combined experimental, theoretical and density functional theory (DFT) analysis, important insights into the effects of structural modifications, such as ligand substitution, on the degree of electronic coupling and rate of electron transfer have been obtained. [ABSTRACT FROM AUTHOR]

An extended nitro-functionalised 1,2,4-triazole ligand has been used to induce considerable lattice distortion in a 2-D Hofmann framework material via competing supramolecular interactions. Single crystal X-ray diffraction analyses on [Fe3(N-cintrz)6(Pd(CN)4)3]·6H2O (N-cintrz: (E)-3-(2-nitrophenyl)acrylaldehyde) reveal a substantial deviation from a regular Hofmann structure, in particular as the intra- and inter-layer contacts are dominated by hydrogen-bonding interactions rather than the typical π-stacking arrays. Also, the 2-D Hofmann layers show an assortment of ligand conformations and local FeII coordination environments driven by the optimisation of competing supramolecular contacts. Temperature-dependent magnetic susceptibility measurements reveal a two-step spin crossover (SCO) transition. Variable temperature structural analyses show that the two crystallographically distinct FeII centres, which are arranged in stripes (2 : 1 ratio) within each Hofmann layer, undergo a cooperative HS ↔ HS/LS ↔ LS (HS = high spin, LS = low spin) transition without periodic spin-state ordering. The mismatch between crystallographic (2 : 1) and spin-state (1 : 1) periodicity at the HS : LS step provides key insight into the competition (frustration) between elastic interactions and crystallographically driven order. [ABSTRACT FROM AUTHOR]

A 3-D FeII Hofmann-type framework material has been prepared which contains a three-connecting pyridyl-donor ligand with amide functionality and [Au(CN)2]− metallo-ligands. The FeII sites display a rare FeII(py)3(N≡C⋯)3 coordination environment, which we show for the first time to be conducive to spin crossover (SCO). [ABSTRACT FROM AUTHOR]

A one-dimensional FeII coordination polymer (CP) has been formed which includes the redox-active ligand bis-pyridyltetrathiafulvalene (py2TTF) and a Schiff base-like N2O2 ligand. This CP is both spin crossover (SCO) and redox-active in the solid-state, and chemical oxidation results in SCO modification. [ABSTRACT FROM AUTHOR]

We probe the effect of heteroatom substitution on the spin crossover (SCO) properties of dinuclear materials of the type [Fe2(NCX)4(R-trz)5]·S (X = S, Se; S = solvent; R-trz = (E)-N-(furan-2-ylmethylene)-4H-1,2,4-triazol-4-amine (furtrz); (E)-N-(thiophen-2-ylmethylene)-4H-1,2,4-triazole-4-amine (thtrz)). For the furtrz family ([Fe2(NCX)4(furtrz)5]·furtrz·MeOH; X = S (furtrz-S) and X = Se (furtrz-Se)) gradual and incomplete one-step SCO transitions are observed (furtrz-S (T1/2 = 172 K) and furtrz-Se (T1/2 = 205 K)) and a structural evolution from [HS–HS] to [HS–LS] per dinuclear species. Contrasting this, within the thtrz family ([Fe2(NCX)4(thtrz)5]·4MeOH; X = S (thtrz-S) and X = Se (thtrz-Se)) more varied SCO transitions are observed, with thtrz-S being SCO-inactive (high spin) and thtrz-Se showing a rare complete two-step SCO transition (T1/2(1,2) = 170, 200 K) in which the FeII sites transition from [HS–HS] to [HS–LS] to [LS–LS] per dinuclear unit with no long range ordering of spin-states at the intermediate plateau. Detailed structure–function analyses have been conducted within this growing dinuclear family to rationalise these diverse spin-switching properties. [ABSTRACT FROM AUTHOR]

This paper reports additional properties of the electron donor molecule triselenathiafulvalene (TSTF) and its synthesis via a new route involving the precursor tetracarbomethoxytriselenathiafulvalene (TCMTSTF). The structural, electronic and computational properties of TSTF are fully profiled, and discussed in the context of the closely related archetypal electron donor molecule tetrathiafulvalene (TTF). TSTF was also incorporated into a charge transfer (CT) complex with the well-known electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ), to generate TSTF–TCNQ. In order to establish its position in the greater TXF–TCNQ series (where TXF = a tetrachalcogenafulvalene), spectral, electrochemical, magnetic, conductivity and computational studies were performed on TSTF and TSTF–TCNQ to extend what is known about the highly interesting and useful new donor molecule. [ABSTRACT FROM AUTHOR]

Two new, isostructural UiO-66-type metal–organic frameworks (MOFs), Zr-PyDC (Zr6O4(OH)5(pyridine-2,5-dicarboxylate)4(formate)3(H2O)34) and Zr-PzDC (Zr6O4(OH)4.75(pyrazine-2,5-dicarboxylate)4.5(formate)2.25(H2O)33) have been synthesised via an unusual high acidity route. Despite the chelating capability of the ligands, which incorporate pyridine and pyrazine N-functionalities, these robust MOFs are linked exclusively through carboxylate donors to leave free Lewis base donor sites. Both MOFs show increased heats of adsorption and higher loadings of CO2 and H2 than UiO-66. High-conversion post-synthetic modification of Zr-PyDC and Zr-PzDC yielded charged, N-methylated frameworks with enhanced gas adsorption capacities. Further, the metal binding properties of Zr-PyDC have been probed by post-synthetic metallation with CuII. [ABSTRACT FROM AUTHOR]

Two organic polymers containing alternating electron donating triarylamine and electron accepting thiazolo[5,4-d]thiazole (TzTz) moieties have been synthesized and their redox states investigated. When donor and acceptor units are proximal (polymer 1), electron density is delocalized, leading to a small electrical and optical band gap; these are larger with the inclusion of an adjoining alkynyl-phenyl bridge (polymer 2), where electron density is more localized due to the rotation of the monomer units. As a result, 1 and 2 display different optical and fluorescence properties in their neutral states. Upon chemical and electrochemical redox reactions, radicals form in both 1 and 2, yielding magnetic materials that display temperature-independent paramagnetism, attributable to delocalization of radical spins along the polymeric backbones. The ability to convert between diamagnetic and paramagnetic states upon chemical oxidation and/or reduction allows for the materials to display switchable magnetism and fluorescence, imparting multifunctionality to these solid-state purely organic materials. [ABSTRACT FROM AUTHOR]

The synthesis, as well as the electrochemical, optical and magnetic properties of a sulfate-bridged Co(ii) dimer, [Co2(DMIM)4(μ2-O2,O,O′-SO4)2]·2MeCN (DMIM = 1,2-dimethylimidazole) (2), are reported. The crystal structure consists of two distorted pseudo-octahedral Co(ii) centres, each ligated by the μ2-(O-O′-sulfato) and μ2-(O2-sulfato) bridging modes of the SO42− anions. Magnetic studies have identified significant antiferromagnetic coupling between the high spin Co(ii) centres, with J = −28 cm−1. Cyclic voltammetry indicated the presence of a quasi-reversible ligand centred oxidation, while the vis-NIR spectrum of 2 revealed complex splitting of the absorption bands due to the tetragonal distortion of the octahedral geometry of the Co(ii) centres. [ABSTRACT FROM AUTHOR]

Eight platinum(II) complexes with anticancer potential have been synthesised and characterised. These complexes are of the type [Pt(IL)(AL)]2+, where IL is either dipyrido[3,2-f:2',3'-h]quinoxaline (dpq) or 2,3-dimethyl-dpq (23Me2dpq) and AL is one of the R,R or S,S isomers of either 1,2-diaminocyclohexane (SS-dach or RR-dach) or 1,2-diaminocyclopentane (SS-dacp or RR-dacp). The CT-DNA binding of these complexes and a series of other complexes were assessed using fluorescent intercalator displacement assays, resulting in unexpected trends in DNA binding affinity. The cytotoxicity of the eight synthesised compounds was determined in the L1210 cell line; the most cytotoxic of these were [Pt(dpq)(SS-dach)]Cl2 and [Pt(dpq)(RR-dach)]Cl2, with IC50 values of 0.19 and 0.80 μM, respectively. The X-ray crystal structure of the complex [Pt(dpq)(SS-dach)](ClO4)2·1.75H2O is also reported. [ABSTRACT FROM AUTHOR]

The properties of atmospheric CO2 fixation, metamagnetism, reversible guest adsorption and zero thermal expansion have been combined in a single robust MOF, [Cu3(bpac)3(CO3)2](ClO4)2·H2O (1·H2O). This compound is a ditopically-bridged copper carbonate kagome lattice where desolvation of the MOF allows subtle tuning of the metamagnetic and uniaxial ZTE behaviour. [ABSTRACT FROM AUTHOR]

A new microporous framework, Zn(NDC)(DPMBI) (where NDC = 2,7-naphthalene dicarboxylate and DPMBI = N,N′-di-(4-pyridylmethyl)-1,2,4,5-benzenetetracarboxydiimide), containing the redox-active benzenetetracarboxydiimide (also known as pyromellitic diimide) ligand core has been crystallographically characterised and exhibits a BET surface area of 608.2 ± 0.7 m2 g−1. The crystallinity of the material is retained upon chemical reduction with sodium naphthalenide (NaNp), which generates the monoradical anion of the pyromellitic diimide ligand in the framework Zn(NDC)(DPMBI)·Nax (where x represents the molar Na+/Zn2+ ratio of 0.109, 0.233, 0.367 and 0.378 from ICP-AES), as determined by EPR, solid state Vis-NIR spectroelectrochemistry and UV-Vis-NIR spectroscopy. The CO2 uptake in the reduced materials relative to the neutral framework is enhanced up to a Na+/Zn2+ molar ratio of 0.367; however, beyond this concentration the surface area and CO2 uptake decrease due to pore obstruction. The CO2 isosteric heat of adsorption (☋Qst☋) and CO2/N2 selectivity (S), obtained from pure gas adsorption isotherms and Ideal Adsorbed Solution Theory (IAST) calculations, are also maximised relative to the neutral framework at this concentration of the alkali metal counter-ion. The observed enhancement in the CO2 uptake, selectivity and isoteric heat of adsorption has been attributed to stronger interactions between CO2 and both the radical DPMBI ligand backbone and the occluded Na+ ions. [ABSTRACT FROM AUTHOR]

Cyanidometallate complexes are highly versatile building units for the generation of functional porous materials. Here we report five new pillared Hofmann layer compounds incorporating the tetracyanidometallates [MoO(CN)4]2−and [MnN(CN)4]2−. These metalloligands, which are new to this class of materials, have been combined with divalent 1st-row transition metals to produce Hofmann layers that are linked into three-dimensional frameworks by ditopic bridging dipyridyls. We report the structures and anomalous thermal expansion properties of five new materials: [Mn(H2O)(bpy)½{MoO(CN)4(bpy)½}]·2H2O (1), [Mn(H2O)(bpy)½{MnN(CN)4(bpy)½}]·2H2O (2), [Fe(H2O)(bpy)½{MnN(CN)4(bpy)½}]·2H2O (3), [Co(H2O)(bpy)½{MnN(CN)4(bpy)½}]·2H2O (4) and [{Mn(H2O)2}½{Mn(bpa)2}½{MoO(CN)4(bpa)½}]·MeOH (5), (where bpy = 4,4′-bipyridine and bpa = 4,4′-bipyridylacetylene). [ABSTRACT FROM AUTHOR]

The metalloligand [Ni(pedt)2]- (pedt = 1-(pyridine-4-yl)ethylene- 1,2-dithiolate) has been incorporated into two multi-dimensional structures for the first time. These coordination frameworks represent highly unusual interpenetration isomers and exhibit solid state redox and optical properties that reflect the electronically delocalised nature of the metalloligand. [ABSTRACT FROM AUTHOR]

The abrupt and hysteretic two-step spin crossover in a new triazole-based 2-D Hofmann-type complex shows a record breaking 120 K intermediate plateau (IP) region stabilized by negative cooperative interactions. [ABSTRACT FROM AUTHOR]

Neutron powder diffraction measurements were carried out on the evacuated and CO2-loaded Prussian blue analogue, Fe3[Co(CN)6]2, identifying two distinct CO2 adsorption sites: site A, in which CO2 uniquely bridges between two bare-metal sites, and site B, in which it interacts in a face capping motif. The saturation of site A at low loadings of CO2 demonstrates the favourable nature of the interaction of CO2 with bare-metal sites within the material. [ABSTRACT FROM AUTHOR]

A new coordination framework material, [Zn{MnN(CN)4(H2O)}]·2H2O·MeOH, has been characterised crystallographically and the effect of a terminal nitride on the N2, H2 and CO2 sorption capacities of the material assessed through porosimetery measurements and DRIFTS. [ABSTRACT FROM AUTHOR]

Powder diffraction is used to study thermal expansion properties of MOF-5 at moderate helium gas pressures: 1.7 bar (100–500 K) and 5–150 bar (150–300 K). The framework shows negative thermal expansion (NTE) at all pressures, but vibrational motions causing NTE are damped with increasing pressures, leading to decreased NTE. [ABSTRACT FROM AUTHOR]

Understanding charge transfer in redox-active metal-organic frameworks (MOFs) is of fundamental importance given the potential of these materials to be used in myriad applications including porous conductors, electrocatalysts and battery materials, amongst others. An important challenge is quantifying the spectroscopic features of these materials in order to elucidate their charge transfer properties. Herein, two topologically related Zn(ii) and Cd(ii) frameworks, [Zn 2 (DPPTzTz) 2 (SDC) 2 ] ( 1-Zn ) and [Cd 2 (DPPTzTz) 2 (SDC) 2 ] ( 2-Cd ) (where DPPTzTz = 2,5-bis(4-(4-pyridinyl)phenyl)thiazolo[5,4- d ]thiazole and SDC = selenophene-2,5-dicarboxylate), incorporating cofacially stacked pairs of redox-active DPPTzTz ligands are presented. The differences in the through-space intervalence charge transfer properties of the mixed-valence forms of the two frameworks generated upon solid state spectroelectrochemical reduction are quantified using Marcus-Hush theory. Further, charge transfer theory is applied to calculate electron mobilities in both extended framework systems. A larger electronic coupling constant, H ab , of 118 cm -1 corresponding to an electron mobility, k , of 6.02 × 10 8 s -1 was observed for the Zn(ii) analogue compared to the Cd(ii) analogue ( H ab = 61.2 cm -1 and k = 2.22 × 10 8 s -1 ) and was correlated primarily with the larger cofacial stacking distance and increasingly offset stacking geometry between DPPTzTz ligands in the latter. Establishing structure-activity relationships in electroactive MOFs, in addition to methods for quantifying their charge transfer properties, represents an important advance in fine tuning solid state materials for device applications.

Dynamically porous metal-organic frameworks (MOFs) with a chiral quartz-based structure have been synthesized from the multidentate ligand 2,2'-dihydroxybiphenyl-4,4'-dicarboxylate (H2diol). Compounds [Ni(II)(H2diol)(S)2]·xS (where S = DMF or DEF) show marked changes in 77 K N2 uptake between partially desolvated [Ni(II)(H2diol)(S)2] (only the pore solvent is removed) and fully desolvated [Ni(II)(H2diol)] forms. Furthermore, [Ni(II)(H2diol)(DMF)2] displays additional solvent-dependent porosity through the rotation of DMF molecules attached to the axial coordination sites of the Ni(II) centre. A unique feature of the four coordinate Ni(II) centre in [Ni(II)(H2diol)] is the dynamic response to its chemical environment. Exposure of [Ni(II)(H2diol)] to H2O and MeOH vapour leads to coordination of both axial sites of the Ni centres and to the generation of a solvated framework, whereas exposure to EtOH, DMF, acetone, and MeCN does not lead to any change in metal coordination or structure metrics. MeOH vapour adsorption was able to be tracked by time-dependent magnetometry as the solvated and desolvated structures have different magnetic moments. Solvated and desolvated forms of the MOF show remarkable differences in their thermal expansivities; [Ni(II)(H2diol)(DMF)2]·DMF displays marked positive thermal expansion (PTE) in the c-axis, yet near to zero thermal expansion, between 90 and 450 K, is observed for [Ni(II)(H2diol)]. These new MOF architectures demonstrate a dynamic structural and colourimetric response to selected adsorbates via a unique mechanism that involves a reversible change in the coordination environment of the metal centre. These coordination changes are mediated throughout the MOF by rotational mobility about the biaryl bond of the ligand.

Complementary experimental techniques and ab initio calculations were used to determine the origin and nature of negative thermal expansion (NTE) in the archetype metal-organic framework MOF-5 (Zn(4)O(1,4-benzenedicarboxylate)(3)). The organic linker was probed by inelastic neutron scattering under vacuum and at a gas pressure of 175 bar to distinguish between the pressure and temperature responses of the framework motions, and the local structure of the metal centers was studied by X-ray absorption spectroscopy. Multi-temperature powder- and single-crystal X-ray and neutron diffraction was used to characterize the polymeric nature of the sample and to quantify NTE over the large temperature range 4-400 K. Ab initio calculations complement the experimental data with detailed information on vibrational motions in the framework and their correlations. A uniform and comprehensive picture of NTE in MOF-5 has been drawn, and we provide direct evidence that the main contributor to NTE is translational transverse motion of the aromatic ring, which can be dampened by applying a gas pressure to the sample. The linker motion is highly correlated rather than local in nature. The relative energies of different framework vibrations populated in MOF-5 are suggested by analysis of neutron diffraction data. We note that the lowest-energy motion is a librational motion of the aromatic ring which does not contribute to NTE. The libration is followed by transverse motion of the linker and the carboxylate group. These motions result in unit-cell contraction with increasing temperature.

The metal-organic framework Ni(2)(dobdc) (CPO-27-Ni, where dobdc = 1,4-dioxido-2,5-benzenedicarboxylate) has been post-synthetically modified with piperazine (pip) - a known 'accelerator' to improve the kinetics of CO(2) uptake in alkanolamine solvents for chemical absorption - and the impact of the modification on the CO(2) uptake and selectivity over N(2) has been probed. While the modified framework, Ni(2)(dobdc)(pip)(0.5) (pip-CPO-27-Ni), exhibits a lower uptake of CO(2) compared with the non-grafted material, the selectivity for CO(2) over N(2) at 25 °C and at pressures pertinent to post-combustion flue gas capture (0.1-0.15 bar) is enhanced. Mechanistically, the interaction between the CO(2) molecules and the free amine sites in pip-CPO-27-Ni occurs via physisorption and chemisorption interactions, in which CO(2) binds to the framework with an isosteric heat of adsorption (-Q(st)) of 40.5 kJ mol(-1) at very low coverage (P = 0.033 mbar), followed by binding at a higher heat of adsorption (-Q(st) = 46.2 kJ mol(-1) at P = 3.55 mbar). Pure water adsorption isotherms revealed a two-step mechanism for uptake in CPO-27-Ni, consistent with adsorption into the first and second hydration spheres of Ni(2+) followed by subsequent uptake via physisorption into the pores. Additional steric hindrance in pip-CPO-27-Ni results in a single step only. The working capacity over multiple cycles was also investigated using a temperature swing adsorption process which revealed reversible CO(2) adsorption and desorption of 10 wt% over 10 cycles.

Three high-spin tetranuclear cobalt(II) complexes have been prepared with the bridging ligand 4,7-phenanthrolino-5,6:5',6'-pyrazine (ppz) through metal-ion directed self-assembly. The complexes differ by the incorporation of three different coordinating anions: chloride, thiocyanide and selenocyanide. The physical properties of these complexes have been investigated in detail.

In this article, techniques for separating mixtures of insoluble compounds are discussed with respect to the small quantities found in laboratory preparations, as opposed to industrial quantities. The techniques include separations based on density, surface area and differences in particle size. Also discussed are simple apparatus, readily available in the laboratory or from commercial suppliers, for achieving these techniques., (This journal is © The Royal Society of Chemistry 2011)

The ligands 4-, 3- and 2-pyridinecarbaldehyde 4'-(2,2':6',2''-terpyridyl)hydrazone (, and ) have been prepared and characterized. In the homoleptic iron(ii) and ruthenium(ii) complexes, the nitrogen donor atoms of the pendant pyridine rings subtend an obtuse angle ( approximately 155 degrees ) at the metal centre, thus providing an expanded ligand, which can be used for the assembly one-dimensional coordination polymers with an undulating backbone. Protonation of the pendant pyridine rings in [FeL(2)](2+) (L = , , ) or [RuL(2)](2+) (L = , ) leads to a colour change from purple to blue, or red to pink, respectively, as the MLCT band shifts to a lower energy. The structural data for [Fe(H)()][PF(6)](3).3.5MeCN.2.5H(2)O (where [H](+) is the monoprotonated ligand) show that the [Fe(H)()](3+) cations form one-dimensional chains supported by N(py)HN(py) hydrogen bonds and that the undulating chains pack to give a porous material, with channels that accommodate the anions and solvent molecules. A single-crystal X-ray diffraction determination of {[Fe(NCS)(2)(Ru()(2))(2)][Fe(2)(NCS)(6)(OEt)(2)(EtOH)(2)][NCS](2).4EtOH.H(2)O}(n) reveals that pairs of [Ru()(2)](2+) cations connect {Fe(NCS)(2)} units to give a one-dimensional polymer comprising of linked metallamacrocycles.

Assembly of the novel homochiral ligand L(S) (where L(S) is 1,4-benzylidene-bis(S,S)-4-yl-3,5-bis(1-hydroxyethyl)-1,2,4-triazole) and AgNO3 generates a robust, porous, chiral and cationic framework that exhibits reversible guest adsorption.

A comparative structural and spectroscopic investigation of the complexes [M(1)2]2+, [M(2)2]2+ and [M(3)2]2+ in which M = Fe or Ru, and ligands 1, 2 and 3 are 4'-(2-pyridyl)-, 4'-(3-pyridyl)- and 4'-(4-pyridyl)-2,2':6',2"-terpyridine, respectively, is reported. The complexes [Ru(1)2]2+, [Ru(2)2]2+ and [Ru(3)2]2+ undergo mono- and bis-N-methylation. The consequences of methylation on the absorption spectra and electrochemical properties are discussed; the solid-state structure of the bis(N-methylated) derivative of [Ru(2)2][PF6]2 is presented.

A range of bis-facial tridentate chelate complexes of type [Fe((R-pz)(3)CH)((3,5-Me(2)pz)(3)CH)](BF(4))(2) has been characterised that contain two different tris-pyrazolylmethane ligands, with variations in R being H (complex crystallised as polymorphs and ) and 4-Me (), as well as R = H with a CH(2)OH arm off the methane carbon (). A tris(pyridyl)methane analogue is also described (). The tris(3,5-dimethylpyrazolyl)methane co-ligand (3,5-Me(2)pz), and the BF(4)(-) counterion, are constant throughout. The spin-crossover properties of these Fe(ii) d(6) compounds have been probed in detail by variable temperature magnetic, Mössbauer spectral and crystallographic methods. The effects of distortions from octahedral symmetry around the Fe(ii) centres, of crystal solvate molecules (1.5 MeCN in and 2 MeCN in ) and of supramolecular/crystal packing, are discussed. In the case of , subtle twisting of pyrazole rings occurs, as a function of temperature, that has a greater effect upon the relative positions of the Fe(ii) chelate molecules in polymorph than in polymorph ; this is thought to drive the cooperativity differences observed in the magnetism of the polymorphs. Comparisons are also made between to and their homoleptic, parent [Fe(L)(2)] (2+) materials. The complexes were screened for the LIESST (light induced excited spin state trapping) effect by measurements of diffuse absorption spectra on the surface of powder samples, at different temperatures. One example, , showed a 2-step thermal spin crossover transition and it was probed in detail for its photomagnetic features. The T(LIESST) and T(1/2) values for did not obey an empirical relationship, T(LIESST) = 150 - 0.3T(1/2) followed by many Fe(ii)(N-donor)(6) crossover compounds of the bis-tridentate (meridional) type, and possible reasons for this are discussed.

Desorption of bound and unbound water molecules from the nanoporous coordination framework ErIII[CoIII(CN)6].4(H2O) to form the apohost, ErIII[CoIII(CN)6], proceeds via a single crystal to single crystal transformation in which the Er(III) cations change from 8- to 6-coordinate; dehydration results in a striking change in the thermal expansion properties.

Coordination framework materials display a rich array of host-guest properties and are notable amongst porous media for their extreme chemical versatility. This article highlights a number of areas where specific function has been incorporated into these framework host lattices.

The family of dehydrated nanoporous Prussian Blue analogues, M(II)3[Co(III)(CN)6]2 (M(II) = Mn, Fe, Co, Ni, Cu, Zn, Cd), which contain coordinatively unsaturated divalent metal cations, undergoes reversible sorption of hydrogen gas up to 1.2 wt% (at 77 K, 101.3 kPa), the capacity of which depends on the metal ion.

Reversible crystal-to-crystal transformation accompanied by change from ferromagnetic to antiferromagnetic ground states at 8 K upon dehydration-rehydration of the nanoporous coordination framework [CoII3(OH)2(C4O4)2].3H2O.

The metal-directed assembly of new molecular frameworks incorporating 4-(4-pyridyl)pyrazole (L), containing non-linear coordination vectors, is presented. Three metallo-arrays of types [Co(LH)2(NO3)4], [Co(LH)2(H2O)4][NO3]4.H2O and [Zn2(L-H)2Cl2].2EtOH are reported. The cobalt(II) in [Co(LH)2(NO3)4] displays distorted octahedral geometry, with the two protonated pyridyl-pyrazole ligands coordinated through their pyrazole nitrogen atoms in a trans-orientation; the remaining four coordination sites are occupied by nitrate anions. Two internal hydrogen bonds occur between each pyrazole NH and the oxygens of adjacent coordinated nitrato ligands. Short intermolecular hydrogen bonds also occur between the two pyridinium hydrogens and bound nitrate ligands on different molecules to yield a two-dimensional hydrogen-bonded array. Two of these arrays interpenetrate to form an extended two dimensional layer; such layers stack throughout the crystal structure. A second product of type [Co(LH)2(H2O)4][NO3]4.H2O exists as two crystallographically independent, but chemically similar, forms. In each form, the two protonated pyridyl-pyrazole ligands occupy trans positions about the cobalt, with the remaining four coordination sites being filled by water molecules to yield a distorted octahedral coordination geometry. Intramolecular hydrogen-bonding is observed between the two non-coordinated pyrazoyl nitrogen atoms and bound water oxygen atoms. The third complex, [Zn2(L-H)2Cl2].2EtOH, contains dimer units consisting of two zinc(II) ions bridged by two pyrazoylate groups in which the coordination geometry of each zinc approximates a tetrahedron. Each zinc is bound to two deprotonated pyridine-pyrazole ligands (L-H), one pyridyl group (from a different dimeric unit) and one chloro ligand. Each pyridyl nitrogen thus connects each of these zinc dimers to an adjacent dimer unit, forming a three-dimensional network containing small voids. The latter are occupied by ethanol molecules which form hydrogen bonds to the chloro ligands.

The molecular framework [Fe(NCS)(2)(tmbpz)(2)](tmbpz = 3,3',5,5'-tetramethyl-4,4'-bipyrazolyl) consists of a robust doubly interpenetrated NbO-type network that remains stable on the removal of solvent guest molecules.