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Three new amine functionalised tetracarboxylate linkers with a variety of arm lengths were synthesised, namely N,N,N′N′-tetrakis(R1, R2 or R3)-trans-1,4-diaminocyclohexane, R1 = (4-carboxyphenyl)-1-methyl; R2 = (4-cinnamic)-1-methyl; R3 = 1′-carboxy-[4,4′-biphenyl]-1-methyl. The diagonal length of the linkers, from single crystal structural analysis and obtained by measuring between the furthest oxygen atoms, is 19.4, 24.6 and 27.5 A for L1, L2 and L3, respectively. The sp3 hybridization of the amino groups of the cyclohexyldiamine core and the carbon atoms of methylene spacers permits the rotation of the attached groups to occur around these atomic sites, giving the ligands a flexibility that manifests itself in two main dominant conformations: convergent, where carboxyl arm groups connected to the same nitrogen atom are π⋯π stacking, and divergent, where two carboxyl arms occupy equatorial positions and two occupy the axial positions relative to the ligand's cyclohexyl core. Analysis of the overall ligand conformations obtained from crystal structures of sixteen new coordination polymers showed that the overwhelmingly most common conformation (93%) was the divergent one. The formulae and topologies of the coordination polymers obtained were: poly-[Cd2(H2L1)(Cl)2(OH2)2]·5H2O (1) 2D (4,4), poly-[M2L2(OH2)2]·DMA M = Cd (2Cd) or Mn (2Mn) 3D (4·62·7·8)(42·66·75·82), poly-[Cd2(L3)(OH2)4(DMF)2] (3) 1D ladder, poly-[Cd2(L3)]·4DMA·16H2O (4) 3D fsc, poly-{((CH3)2NH2)4[Zn4Na4(L1)4(OH2)4(DMF)2]} (5) 3D pts, poly-[M5(HL1)2(O)2(OH2)2(DMF)2]·solv M/solv = Zn/2DMF·18H2O (6Zn) or Co/9DMF·10H2O (6Co) 3D cyc, poly-[Zn3(L1)(OH)2]·2DMF (7) 3D fsc, poly-{((CH3)2NH2)[Zn2(HL2)(O)]·DMF} (8) 3D pts, poly-[Zn8(L3)3(O)2]·16DMF (9) 3D fsy, poly-[Cu2(L1)(DMF)2] (10) 2D (4,4), poly-[Cu2(L2)(OH2)2] (11) 3D lvt, poly-[Na4Zr2(L1)3(DMF)4] (12) 3D (44·52)2(44·5·6)(46·513·68·7)2, poly-[Zr6(HL1)2(O)8(CH3COO)2(OH2)6] (13) 3D scu, and poly-[Co2K4(L1)2(DMF)3] (14) 3D (42·64)(42·610·83). Although we applied similar reaction conditions, none of the coordination polymers obtained with L1, L2 & L3 were isoreticular upon ligand change. The overall trend is of void space increase by using longer ligands but with no notable increase in the level of interpenetration. The predictability and control of the obtained frameworks was hindered by the formation of non-default topologies due to the high flexibility of the tetracarboxylate linkers used and the variety of metal nodes observed.

Mixed donor phenanthroline-carboxylate linkers were combined with MnII or ZnII to form photoactive MOFs with large pore apertures. The MOFs display high CO2 adsorption capacities, which consequently causes structural framework flexibility, and align with favorable metrics for selective CO2 capture. The photophysical properties of the MOFs were investigated, with the MnII MOF giving rise to short triplet LMCT lifetimes.

One prominent aspect of metal organic frameworks (MOFs) is the ability to tune the size, shape, and chemical characteristics of their pores. MOF-5, with its open cubic connectivity of Zn 4 O clusters joined by two-dimensional, terephthalate linkers, is the archetypal example: Both functionalized and elongated linkers produce isoreticular frameworks that define pores with new shapes and chemical environments. The recent scalable synthesis of cubane-1,4-dicarboxylic acid (1,4-H 2 cdc) allows the first opportunity to explore its application in leading reticular architectures. Herein we describe the use of 1,4-H 2 cdc to construct [Zn 4 O(1,4-cdc) 3 ], referred to as CUB-5. Isoreticular with MOF-5, CUB-5 adopts a cubic architecture but features aliphatic, rather than aromatic, pore surfaces. Methine units point directly into the pores, delivering new and unconventional adsorption locations. Our results show that CUB-5 is capable of selectively adsorbing high amounts of benzene at low partial pressures, promising for future investigations into the industrial separation of benzene from gasoline using aliphatic MOF materials. These results present an effective design strategy for the generation of new MOF materials with aliphatic pore environments and properties previously unattainable in conventional frameworks.

The use of flexible ligands in coordination polymers provides both opportunities and unpredictability. A new series of flexible ligands derived from p-xylylenediamine, which vary in the positioning of carboxylic acid functional groups, have been found to form a series of coordination polymers and a discrete coordination complex. Use of the tetra-substituted meta-carboxylic acid ligand N,N,N′,N′-tetra(3-carboxybenzyl)-p-xylylenediamine, isolated as its dihydrochloride salt (H6M4pxy)Cl2, resulted in the simultaneous formation of two products from the same synthetic conditions. One of these products was a discrete cage-type coordination complex of the form [Cu4(M4pxy)2(DMF)2(OH2)] (1), while the other product was the two-dimensional coordination polymer poly-[Cu2(M4pxy)(OH2)2] (2). Synthesis utilising the tetra-substituted para-carboxylic acid ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-p-xylylenediamine dihydrochloride (H6P4pxy)Cl2, resulted in the formation of multiple two-dimensional coordination polymers, poly-[Cu2(P4pxy)(DMF)(OH2)]·2DMF·3H2O (3·2DMF·3H2O), poly-[Mn2(P4pxy)(DMA)2] (4), poly-[Co4(P4pxy)2(DMF)2(μ-OH2)2(OH2)2]·6DMF·4H2O (5·6DMF·4H2O) and poly-[Cd2(P4pxy)(OH2)2]·DMA·3H2O (6·DMA·3H2O). The last of these materials, a three-dimensional coordination polymer, was found to adsorb approximately 32 cm3 g−1 STP of CO2 at atmospheric pressure at 273 K.

The resurgence of interest in the hydrogen economy could hinge on the distribution of hydrogen in a safe and efficient manner. Whilst great progress has been made with cryogenic hydrogen storage or liquefied ammonia, liquid organic hydrogen carriers (LOHCs) remain attractive due to their lack of need for cryogenic temperatures or high pressures, most commonly a cycle between methylcyclohexane and toluene. Oxidation of methylcyclohexane to release hydrogen will be more efficient if the equilibrium limitations can be removed by separating the mixture. This report describes a family of six ternary and quaternary multicomponent metal-organic frameworks (MOFs) that contain the three-dimensional cubane-1,4-dicarboxylate (cdc) ligand. Of these MOFs, the most promising is a quaternary MOF (CUB-30), comprising cdc, 4,4'-biphenyldicarboxylate (bpdc) and tritopic truxene linkers. Contrary to conventional wisdom that adsorptive interactions with larger, hydrocarbon guests are dominated by π-π interactions, here we report that contoured aliphatic pore environments can exhibit high selectivity and capacity for LOHC separations at low pressures. This is the first time, to the best of our knowledge, where selective adsorption for cyclohexane over benzene is witnessed, underlining the unique adsorptive behavior afforded by the unconventional cubane moiety.

Porous coordination polymers, or metal–organic frameworks (MOFs), provide a unique materials platform due to their regular structure that allows for almost unlimited tunability in terms of pore size, shape, dimensionality and chemical functionalisation. The ability of this class of material to act as agents for the selective capture or separation of small molecules has driven much of the research in the field over the past two decades. One of the major driving forces in recent years has been the ability of porous coordination polymers to act as selective hosts for carbon dioxide, with obvious potential environmental implications for successful materials. Efforts to enhance the selectivity for CO2 over other gases (particularly those present in exhaust flues) have explored chemical functionalisation of the interior pore space using amines, to give materials that to some extent mimic the standard solution-based processing methods of flue gas that are currently employed. This review examines the three major synthetic routes that are used in order to affect this chemical modification of porous frameworks; (i) post-synthetic grafting of amines to coordinatively unsaturated metal sites, (ii) incorporation of ligands that contain terminal amine groups, and (iii) incorporation of ligands that contain amine embedded within the core of the ligand. The relative merits and shortcomings of these different synthetic approaches are discussed alongside examples of the materials generated using each method.

Reactions of ortho-, para- and substituted meta-xylenyl bridged bis(tacn) ligands with two or three molar equivalents of Zn(NO3)2·6H2O at pH 5.0 in the presence of NaClO4 or NH4PF6 resulted in the formation of a range of crystalline zinc complexes. In the presence of perchlorate counter ions the Lpx and Lphx ligands gave rise to dinuclear Zn2+ coordination complexes [Zn2Cl2(Lpx)(H2O)2](ClO4)2(H2O) and [Zn2Cl2(Lphx)(H2O)2](ClO4)2(H2O)2 respectively, which formed infinite 1D polymeric chains. In contrast, in the presence of the hexafluorophosphate counter ion, the Lnix ligand formed a unique tetranuclear Zn2+ complex, [Zn2Cl2(Lnix)(H2O)3](Cl)(PF6)2(H2O)4, the Lcax ligand formed an octanuclear complex [Zn8Cl4(Lcax)4(H2O)10](PF6)6.7(NO3)1.3(H2O)3.3, whilst the Lox ligand formed a mononuclear sandwich structure, [Zn(Lox)](PF6)2(H2O). The protonated metal-free Lpx ligand crystallised as [H4(Lpx)](NO3)2(PF6)(H2O)2 with the stacked ligand cations forming a hydrogen-bonded network. These structural attributes provide an explanation for the significant differences in binding behaviour of recombinant N-terminally tagged proteins with the corresponding Zn2+-azamacrocyclic complexes, compared to the analogous Cu2+- or Ni2+-azamacrocyclic complexes, when immobilised onto support materials and used as immobilised metal affinity chromatographic (IMAC) adsorbents.

Fourteen three-dimensional (3D) lanthanide coordination polymers (CPs) with dicarboxylate mixed ligands, [Ln(fum)1.5(H2O)2]·0.5(H2bdc)·H2O (Ln = Sm (1), Tb (2)), [Ln2(fum)2(bdc)(H2O)4]·2H2O (Ln = Sm (3), Eu (4), Tb (5), Er (6)), [Ln(fum)0.5(bdc)] (Ln = Sm (7), Eu (8), Tb (9), Er (10)), and [Ln2(bdc)2(ox)(H2O)4]·0.7H2O (Ln = Sm (11), Gd (12), Tb (13), Dy (14)), have been synthesized hydrothermally from the self-assembly of lanthanide(III) ions (Ln3+), fumaric acid (H2fum), and terephthalic acid (H2bdc) in the presence of potassium hydroxide at different temperatures. The compounds fall into four classes. Compounds 1 and 2 were isolated from hydrothermal reactions performed at a relatively low temperature of 100 °C and found to crystallize in the triclinic space group P. The 3D framework is assembled from 2D layers of [Ln(fum)(H2O)2] units pillared by the chelating fum ligands and has 1D rhombic channels templated by H2bdc and lattice H2O molecules. The framework presents a binodal (4,5)-connected tcs topology with the point symbol (44·62)(44·66). Raising the reaction temperature to 140 °C resulted in the formation of compounds 3–6. These materials crystallize in the monoclinic system with the polar space group P21 and feature a 3D network constructed from dinuclear {Ln2(OCO)6(H2O)4} units interlinked by fum and bdc ligands, showing a uninodal 6-connected two-fold interpenetrated pcu topology. The small channels of the framework are occupied by lattice H2O molecules. Further increase of the reaction temperature to 160 °C gave rise to the formation of compounds 7–10, crystallizing in the orthorhombic space group Pbca. The 3D framework is generated from 2D corrugated sheets of [Ln(fum)]2+ bound by bdc ligands and contains no intercalated H2O molecules in the lattice. The framework possesses a trinodal (4,6,7)-connected net with the point symbol (42·64)2(46·68·8)(412·69)2. Finally, compounds 11–14 contained an in situ generated oxalate (ox) ligand formed under hydrothermal conditions conducted at a high reaction temperature of 180 °C. These compounds crystallize in the monoclinic space group P21/c and possess a 3D open framework consisting of a dinuclear [Ln2(ox)(H2O)4]2+ unit linked by bridging bdc ligands and has small void channels occupied by lattice H2O molecules. The frameworks were topologically simplified as a binodal (4,5)-connected tcj/hc net with a total point symbol of (42·52·72)(42·53·75). In the solid state at room temperature, the Tb (2, 5, 9, and 13) and Eu (4 and 8) compounds emit green and red light, respectively.

A new Cd(II) based metal–organic framework (MOF), having formula {(CH3)2NH2)6[Cd5(L)4]·H2O·3DMF}n (1), has been synthesized based on a rigid tetracarboxylate ligand of terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4L). 1 shows a complicated 3D tetranodal 3,3,4,8-c network with uncoordinated –COO− groups. The highly selective luminescent sensing of 2,4-dinitrophenol (2,4-DNP), 2,4,6-trinitrophenol (TNP) and ferric ions was studied for 1 through the alleviation in its fluorescence intensity. The detection limit of 2,4-DNP was found to be 0.84 ppm, which is 20 times higher than that of 1,3,5-trimethylbenzene, demonstrating greater and selective quenching ability. The possible mechanism associated with the decrease in fluorescence intensity of 1 in the presence of nitroaromatics (NACs) has been addressed by theoretical calculations. Furthermore, 1 displays excellent capacity to adsorb methylene blue (MB) with high selectivity, and it maintains an almost identical adsorption performance after being recycled five times.

A new metal–organic framework, formulated as {[Zn2(L)(DMF)3]·2DMF·2H2O} (1), has been synthesized using a symmetrical rigid carboxylate ligand terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4L). Single-crystal X-ray diffraction analysis shows that 1 possesses a 3D uninodal 4-c lonsdaleite (lon) topology based on binuclear Zn clusters. 1 behaves as a fluorescent chemosensor for highly selective and sensitive detection of Fe3+/Fe2+ ions, 2,4-dinitrophenol (2,4-DNP), p-nitrophenol (PNP) and 2,4,6-trinitrophenol (TNP). Furthermore, the photocatalytic properties of 1 for degradation of methyl violet (MV) and Rhodamine B (RhB) have been explored. The possible emission quenching of 1 in the presence of aromatic compounds has been addressed by theoretical calculations and the photocatalytic activity of 1 against organic dyes has been addressed using density of states (DOS) calculations.

A traditionally good chelating motif has been incorporated into a ligand for the synthesis of coordination polymers with vacant amine sites. A novel tetracarboxylic acid diamine ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-1,3-diaminopropane dihydrochloride trihydrate (H6L1)Cl2·3H2O, has been prepared, structurally characterised, and subsequently used in the formation of three new coordination polymers. Poly-[Cu2(L1)(OH2)2]·6DMF·3H2O 1 consists of (4,4) sheets formed by each L1 ligand coordinating to four copper(II) ‘paddlewheel’ dinuclear clusters. The amines of the ligand are non-coordinating. After solvent exchange and evacuation, 1 was found to adsorb approximately 23 cm3(STP) g−1 of CO2 at atmospheric pressure at 273 K. The isostructural compounds poly-[Zn(H2L1)(OH2)]·DMF·4H2O and poly-[Cd(H2L1)(OH2)]·DMF·3H2O 2Zn/2Cd are self-penetrating (10,3) coordination polymers containing square-shaped one-dimensional solvent channels. After solvent exchange it was found that 2Zn and 2Cd lost crystallinity, which accounts for the low N2 and CO2 uptakes observed.

An unexploited pentacarboxylate ligand, 2,5-bis(3′,5′-dicarboxylphenyl)-benzoic acid (H5L), was designed and used for the preparation of metal organic material using Zn2+ as a node. The new compound, {(Me2NH2)[Zn2(L)(H2O)]·0.5DMF}n (1) (DMF = dimethylformamide), has been synthesized and structurally characterized. The topology of the 5-connected anionic framework may be described as (44)(66) (Schlafli symbol) based on {M2(CO2)5} molecular building blocks (MBBs) and L ligands in 1. It has been demonstrated that 1 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+, with a detection limit of 0.54 ppm for 2,4,6-trinitrophenol (TNP) and 0.81 ppm for Fe3+. The possible emission quenching mechanism in the presence of nitroaromatics has been addressed by theoretical calculations.

Holstein calves fed pasteurized waste milk were blocked by sex and randomly assigned to 1 of 3 treatment groups, control with no vitamin supplementation (CON, n = 18) and 2 levels of an oral vitamins A, D, and E supplement: 0.25 mL/d of supplement (0.25ADE, n = 12) or 0.5 mL/d of supplement (0.5ADE, n = 10). The supplemented calves also received a 5 mL subcutaneous injection of vitamins A, D, and E at birth. The oral and injectable supplements contained 50,000 international units (IU) of vitamin A as retinyl-palmitate, 50,000 IU of vitamin D3, and 500 IU of vitamin E as RRR-α-tocopherol per milliliter of product. Concentrations of 25-hydroxyvitamin D and a-tocopherol, but not retinol, in serum of 0.25ADE and 0.5ADE calves were greater than CON calves. We observed that supplemented calves gained less weight compared with CON calves in the first 28 d; however, height and starter grain intakes did not differ among treatments. Incidence of respiratory infection or diarrhea did not differ among groups. In conclusion, injection plus supplementation of pasteurized waste milk with vitamins A, D, and E increased concentrations of 25(OH)D and a-tocopherol in serum but decreased body weight gain, due possibly to over-supplementation of the vitamins., The Bovine Practitioner, Vol. 53, No. 2 (2019 Summer)

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 metal–organic framework having formula {[Cd3(H2O)(L)2][Cd(im)3(H2O)2]·3 H2O} (H4L = 5-bis(4-carbonylbenzyl)aminoisophthalic acid and im = imidazole) (1) has been synthesized. X-ray investigation reveals that 1 is rare 4,4,8-connected (46)(45 · 6)(411 · 615 · 82) topology. The present work indicates that 1 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 luminescent property of 1 in different solvents analytes as well as nitrobenzene have been investigated and the observed quenching in fluorescence have been corroborated by theoretical calculations.

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.

Two new isomeric bis(tacn) ligands, 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)-1-(hydroxymethyl)-benzene (HLhyx) and 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)anisole (Lanx) have been synthesised. In addition, 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)-4-methylphenol (HLohx) was also synthesised in a considerably higher yield than the previously reported method. The ligands were reacted with two equivalents of Cu(NO3)2·3H2O at pH 5 resulting in the formation of three binuclear complexes. The ligands Lanx and HLhyx form complexes [Cu2Cl3(L)(H2O)](PF6) containing two unique Cu2+ centres coordinated to the ligand. In contrast, the phenolic HLohx ligand forms a bridged complex [Cu2(μ-Cl)(Lohx)](PF6)2, with the two Cu centres further linked by (μ-Cl) and (μ-O) bridges.

The synthesis, characterizations and crystal structures for [Cu(ipnm)(hmpH)] (1), mixed-valent tetranuclear [MnII2MnIII2(dcnm)2(hmp)6Cl2] (2) and the homo-valent hexanuclear [FeIII6(dcnm)6(hmp)8O2] (3), (where ipnm = imido[cyano (picolinoyl)methyl]nitrosomethanide, hmpH = 2-hydroxymethylpyridine; dcnm = dicyanonitrosomethanide) are reported. The formation of new dianionic ligand, ipnm which is also an imide derivative, represents the scarce example of metal-mediated in-situ dehydrogenative cross-coupling between amide derivatives with primary alcohol. Structure of 2 is known as ‘butterfly’ type structure while hexanuclear cluster 3 exists in chair-like conformation which in both structures, the dcnm acting as a terminal ligand.

A new divergent ligand, N,N′-bis(4-carboxyphenylmethylene)ethane-1,2-diamine (H4L1), has been prepared in high yield and used to generate two copper(II) coordination polymer materials, poly-[Cu(H2L1)(OH2)]·H2O (1) and poly-[Cu(H2L1)(OH2)]·H2O·DMF (2). Both networks possess (4,4) sheet topologies and have almost identical compositions and coordination modes. The only major difference between the compounds lies with the conformation of the chelating ethylenediamine cores; compound 1 adopts a trans-(R,R/S,S) conformation, while compound 2 exhibits a cis-(R,S) conformation. This seemingly small difference arising from variation in synthetic conditions influences the extended structures of each network through hydrogen bonding interactions, resulting in the formation of a close packed 2-fold 2D → 2D parallel interpenetrated network for 1, while the extended, non-interpenetrated structure of 2 contains aligned one-dimensional solvent channels. After solvent exchange and evacuation, compound 2 was found to adsor...

A new piperazine-derived ligand has been prepared and used to synthesise a porous coordination polymer which displays selective carbon dioxide uptake after solvent exchange and thermal activation. The ligand N,N′-bis(4-carboxyphenylmethylene)piperazine H2L1 was prepared from piperazine in three steps and good yield. A structure containing the deprotonated form K2L1·2H2O was determined and consists of a three-dimensional coordination polymer containing inorganic K2(COO)2(OH2) layers separated by the long organic bridging linker. The free compound H2L1 displays a one-dimensional hydrogen-bonded polymeric structure in the solid state with hydrogen bonding interactions between carboxylic acids and piperazine groups tightly linking molecules together. The two-dimensional polymeric complex [Zn3(L1)2(OH)2]·2DMF·0.5H2O 1 was prepared and analysed in the solid state to reveal tubular one-dimensional channels which, when activated by solvent exchange and evacuation, displayed selective affinity for CO2 over N2 and H2.

A new metal–organic framework having formula {[NH2(CH3)][Cu6(L)3(OAc)(H2O)4]·xsolvent} (H4L = 3,5-bis(isophthalic acid)-1H-1,2,4-triazole) (1) was synthesized, in which two types of polyhedral cages and one-dimensional channels coexist. The incorporation of the drug 5-fluorouracil (5-FU) into the desolvated 1 was around 24.9 wt% per gram of dehydrated 1. 5-FU is released in a controlled and progressive fashion with 98% of the drug released after 120 h at PBS. The result from this work provides a new avenue for MOF to be used as potential drug delivery.

The utility of the pyrazole-carboxylate mixed ligand system has been probed with the synthesis of five new coordination polymers, derived from bis-pyrazole ligand 4,4′-methylenebis(3,5-dimethyl-1H-pyrazole) H2L1, large semirigid dicarboxylate coligands, and the deliberately designed and synthesized ligand para-((3,5-dimethyl-1H-pyrazol-4-yl)methylene)benzoic acid H2L4. Complex poly-[Co(H2L1)(L2)(OH2)]·1/2H2O 1 features the coligand (S,S)-1,4,5,8-naphthalenetetracarboxylic diimide-N,N′-bis(2-propionate) L2, and comprises chiral two-dimensional sheets, associating via substantial π–π stacking interactions. Complexes 2 and 3 contain the coligand 1,4-bis((3-carboxyphenyl)methyl)piperazine L3. Complex poly-[Co(H2L1)2(L3)] 2 is a two-dimensional polymer containing octahedral Co(II) ions, whereas modifying the synthesis conditions gave complex poly-[Co2(HL1)2(L3)] 3, a three-dimensional α-Po structure containing pyrazolate-bridged dimers of tetrahedral Co(II) ions, displaying weak antiferromagnetic coupling. Mag...

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.

Two isostructural series of compounds NH4[Ln(cdm)4(H2O)4]·18c6·3H2O (1Ln) and [K(18c6)(H2O)2][Ln(cdm)4(H2O)4]·H2O (2Ln) have been synthesised and structurally characterised (Ln = Gd, Dy, Er, cdm = C(CN)2(CONH2)−). These two classes of compounds are shown to be essentially isostructural to each other despite the change in counter-cation (ammonium vs. potassium) and the ensuing changes in coordination and hydrogen-bonding of water molecules in the structure. Structural data for 1Dy and 2Dy have been obtained using single crystal Laue neutron diffraction, allowing the precise location of all hydrogen atoms to be determined using fully anisotropic models. Both 1 and 2 contain the anionic complex [Ln(cdm)4(H2O)4]− in which the 8-coordinate lanthanoid is coordinated by a ring of four O-bound cdm ligands supported by inter-ligand N–H⋯O hydrogen bonds. The structures pack with complicated hydrogen-bonding networks in which both coordinated and non-coordinated water molecules are hydrogen-bond donors and all of the nitrile groups of the cdm ligands are hydrogen-bond acceptors. The change in cation between ammonium and potassium affects two water molecule sites which are both coordinated in 2Ln but not in 1Ln; in 1Ln one of these water molecules forms a hydrogen bond with NH4+ whilst the other has neither a coordination interaction nor a hydrogen bond to its oxygen atom.

In a study of multifunctional ('hybrid') molecular materials, with one function being spin-crossover and the second being reversible redox behaviour, we describe ferrocene-appended ligands and their d(6) and d(7) complexes trans-[Fe(II)(FTP)2(NCS)2] (1), [Co(II)(FTTP)2](ClO4)2·2(MeCN) (2) and [Fe(II)(FTTP)2](ClO4)2·Et2O (3) (where FTP = 4-(2-pyridyl)-1H-1,2,3-triazol-1-ylferrocene and FTTP = 4'-ferrocenyl-2,2':6',2''-terpyridine). The structures, magnetism and solution electrochemistry are described. Complex 1 remains high-spin, 2 displays gradual, incomplete spin crossover and 3 remains low-spin between 350-2 K. The electrochemical results show that one-electron oxidations at the ferrocene group, located external to the coordination site, occur at more positive potentials than the 'inner' M(II/III) couple in 1 and 2, but not in 3, and this has implications for retaining and influencing spin transitions at the M(II) centres, in future.

The initial pH in the preparation of STA-16(Co) was found to have a great impact on the assembly of the MOF and the resulting porosity. The formation of a non-porous Co(II)-phosphonate pillared layer-structure was observed after changing the initial pH from 6.2 to 7.2 with distinct differences in the coordination environment of the cobalt centres.

Two new bis-(cyanobenzyl)piperazine ligands have been prepared, and have been used to prepare five Ag(I) coordination polymers which have been structurally characterised. Ligand N,N′-bis((4-cyanophenyl)methyl)piperazine L1 gave two structurally related two-dimensional coordination polymers poly-[Ag2(L1)(CF3SO3)2] 1 and poly-[Ag2(L1)(CF3SO3)2(C3H6O)1.5] 2 when reacted with silver trifluoromethanesulfonate in tetrahydrofuran and acetone, respectively. Compounds 1 and 2 display similar ligand geometries but form different extended networks, as a result of the inclusion of coordinating solvent molecules and the resulting influence on the flexible metal geometry. Reaction of N,N′-bis((3-cyanophenyl)methyl)piperazine L2 with silver ions gave rise to three new structurally characterised species. Complex poly-[Ag2(L2)(C3H6O)2]2(PF6) 3 forms a one-dimensional chain structurally related to 1. Complex poly-[Ag2(L2)(C3H8O)2(CF3SO3)2] 4 formed under similar conditions to 3, except with the inclusion of a coordinating anion which links equivalent chains to those found in 3 into a two-dimensional sheet. Finally, complex poly-[AgL2]CF3SO35 was formed simply by altering the reaction stoichiometry, producing a three-dimensional PtS network containing linear, acentric anion channels. Analysis of the structures reveals that the ligand geometries are largely consistent, leading to the extended structures being more influenced by the nature of the anions and solvent molecules.

A novel porous metal–organic framework, {[Zn2(L)·H2O]·3H2O·3DMAc·NH2(CH3)2}n (Zn(II)–MOF), was synthesized under solvothermal conditions using a flexible multicarboxylic acid (H5L = 3,5-bis(1-methoxy-3,5-benzene dicarboxylic acid)benzoic acid). Zn(II)–MOF contains 1D nanotubular channels of 13.8 A × 16.4 A and exhibits a rare 5-connected vbk net with a Schlafli symbol of {45.65} topology. Notably, Zn(II)–MOF can adsorb toluidine blue fast and effectively, and trap lanthanide ions such as Eu3+ and Tb3+ to sensitize their emissions in the solid state through a Ln3+-exchanged approach. Furthermore, we successfully obtained white light emitting materials.

Two divergent ligands 1,4,7,10-tetrakis-(4-cyanobenzyl)-1,4,7,10-tetraazacyclododecane L1 and 1,4,7,10-tetrakis-(4-carboxybenzyl)-1,4,7,10-tetraazacyclododecane dihydrochloride dihydrate H6L2·2Cl·2H2O have been prepared and structurally characterised, and the solid-state structures of four new metal complexes have been elucidated. Ligand L1 was found to form a dimeric complex of the form [Ag2(L1)2]·2ClO4 when reacted with silver perchlorate, in which a macrocycle-bound Ag(I) ion is coordinated by the nitrile group of an adjacent ligand, forming a tightly-bound pair of Ag(I) ions supported by intramolecular π–π interactions. Compound H6L2·2Cl·2H2O was prepared by a solvothermal recrystallization following hydrolysis of the ester precursor, and forms a densely packed three-dimensional structure containing numerous hydrogen bonding interactions. Complexes [Ni(H4L2)Cl]2·[NiCl4]·2EtOH 2 and [Co(H4L2)Cl]2·[CoCl4]·2EtOH 3 were characterised as isostructural discrete macrocycle-bound Ni(II) and Co(II) species where the formation of rare hydrogen-bonded carboxylic acid tetramers gives rise to a series of 2-dimensional sheets, containing checkerboard-type cavities encapsulating alternating tetrachloridometallate anions and regions containing disordered solvent molecules. Complex poly-{[Cu2Cl(H2L1)(HOEt)]2·[CuCl4]·5H2O} 4 consists of a series of two-dimensional sheets formed from a macrocycle-bound CuCl species linked by copper paddlewheel clusters and hydrogen-bonded carboxylic acid dimers. Charge balance is again achieved by tetrachloridometallate anions, and the sheets undergo parallel 2D → 2D interpenetration. The influence of the flexible geometry and donor ability of the methylene-linked pendant arms is clearly visible when comparing discrete complex 1 with hydrogen-bonded networks 2 and 3 and polymeric species 4. The presence of tetrachloridometallate counterions resulting from the presence of excess chloride ions in the reaction mixtures also provides powerful structure-directing effects in complexes 2, 3 and 4.

Conventional bench top and solvothermal synthesis are determined to be reliable methods in the synthesis of coordination compounds containing the dicyanonitromethanide (dcnom) anion. From conventional bench top synthesis, [Ni(phen)3](dcnom)2 (1a), [Cu(phen)3](dcnom)2 (1b), [Cu(en)3](dcnom)2 (4), [Cu3(Hpz)3(H2O)(OH)(pz)3]Cl(dcnom)·H2O (7) and [Ag(Hpz)2(dcnom)] (8) (where phen = 1,10-phenanthroline, en = 1,2-ethylenediamine, Hpz = pyrazole and pz = pyrazolate) are obtained. With solvothermal synthesis, [Ni(phen)2(H2O)(dcnom)](dcnom) (2), [Cu(phen)2(dcnom)](dcnom) (3), [Cu(en)2(dcnom)2] (5) and [Cu(pn)2(dcnom)2] (6) (where pn = 1,3-propylenediamine) are formed. Both nitro κ1(O) and nitrile κ1(N) coordination modes are observed for the dcnom anion.

Metal cluster core expansion at tetrahedral group 6-group 9 mixed-metal clusters MIr3(μ-CO)3(CO)8(η(5)-L) (M = W, Mo, L = C5H5; M = Mo, L = C5Me5) with the iridium capping reagents Ir(CO)2(η(5)-L') (L' = C5Me5, C5Me4H) in refluxing toluene afforded the trigonal-bipyramidal clusters MIr4(μ-CO)3(CO)7(η(5)-C5H5)(η(5)-L') (M = Mo, L' = C5Me5, 1a; M = W, L' = C5Me5, 1b; M = Mo, L' = C5Me4H, 1c; M = W, L' = C5Me4H, 1d) and MoIr4(μ3-H)(μ-CO)2(μ-η(1):η(5)-CH2C5Me4)(CO)7(η(5)-C5Me5) (2). Related reactions with M2Ir2(μ-CO)3(CO)7(η(5)-L)2 (M = W, Mo, L = C5H5; M = Mo, L = C5Me5) afforded M2Ir3(μ-CO)3(CO)6(η(5)-C5H5)2(η(5)-L') (M = Mo, L' = C5Me5, 3a; M = W, L' = C5Me5, 3b; M = Mo, L' = C5Me4H, 3c; M = W, L' = C5Me4H, 3d), W2Ir3(μ-CO)4(CO)5(η(5)-C5H5)2(η(5)-C5Me4H) (4), and Mo2Ir3(μ-CO)3(CO)6(η(5)-C5Me5)3 (5). Single-crystal X-ray diffraction studies of 1a-1d, 2, 3a-3d, and 4 confirmed their molecular structures, including the μ-η(1):η(5)-CH2C5Me4 ligand at hydrido cluster 2, derived from a C-H bond activation of one of the methyl groups. Density functional theory (DFT) studies were employed to suggest the structure of 5. The redox behavior of the new clusters was examined through cyclic voltammetry; all clusters exhibit oxidation and reduction processes (with respect to the resting state), with the oxidation processes being the more reversible, and increasingly so on decreasing Ir content of the clusters, replacing W by Mo, and increasing alkylation of the cyclopentadienyl ligands. In situ IR and UV-vis-near-IR spectroelectrochemical studies of the reversible oxidation processes in 1a and 3a were undertaken, with the spectra of the former suggesting progression to an all-terminal CO geometry concomitant with the first oxidation and a significant structural change upon the second oxidation step. DFT studies of 1a revealed that its crystallographically-confirmed Mo-equatorial core geometry is essentially isoenergetic with a possible Mo-apical isomer, and identified several bridging CO structures for the charged states.

The transition metal-promoted in situ nucleophilic addition of methanol and ethanol to a nitrile arm of dicyanonitrosomethanide (dcnm) resulted in the formation of cyano[imino(methoxy)methyl]nitrosomethanide (cmnm) and cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) respectively. In the presence of 4,4′-bipyridine (4,4′-bipy), [Ni(cmnm)2(4,4′-bipy)]·½DMF (1), [Ni(cenm)2(4,4′-bipy)]·EtOH (2) and [Zn(cmnm)2(4,4′-bipy)]·2H2O (3) were isolated as 1D chains. When copper ions were used, a dinuclear structure, namely [Cu2(cmnm)4(4,4′-bipy)] (4) was observed. Synthesis of 1, 2 and 4 also required the presence of CeCl3·6H2O. The cmnm ligands in complex 3 display unique coordination modes to the metal ions, namely κ2(N,O)Zn. Finally, the hydrogen bonding in 3 generates three interpenetrating 3D networks with unusual bsn (or β-Sn) net topology.

This review gives an account of the coordination polymers that can be attained with ligands containing the sulphur-based dithiocarbamate (dtc), dithiocarboxylate and xanthate functional groups. The coordination modes adopted by the different sulphur-based ligands are discussed, and methods of attaining higher dimension complexes outlined. The review also addresses potential applications of such materials.

The variable-length azacrown ether bridging ligand N,N′-bis(3-pyridyl-methyl)diaza-18-crown-6 (b3pmdc) was reacted with cuprous iodide to give a range of new discrete and polymeric coordination compounds. Six structurally diverse CuI(b3pmdc) architectures were isolated, as well as a single oxidized CuII(b3pmdc) species. These include the helical one-dimensional (1D) chain [H4b3pmdc][Cu10I14]·CHCl3·2H2O (1), the luminescent linear cluster chain [Cu4I6(H2b3pmdc)] (2), the guest water containing network [Cu4I4(Hb3pmdc)2](1.5ClO4)(0.5I3)·3.5H2O·2.5MeOH (3), the luminescent cubane cluster chain [Cu4I4(b3pmdc)2] (4), the three-dimensional (3D) net [Cu9I12(Kb3pmdc)3(H2O)4]·9MeOH (5), the dinuclear mixed halide [Cu2Cl3.4I2.6(H4b3pmdc)] (6), and the cupric 1D chain [CuCl2(H2b3pmdc)(MeOH)2]·2Cl·2MeCN (7). Manipulation of the ligand conformation was achieved by the addition of the alkali metal salt potassium and by varying the pH of the solution with a range of acids (HCl, HClO4). In the case of 2 and 4, green and y...

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.

Three manganese clusters have been synthesised via the reaction of Mn II with cyano(imino(methoxy)methyl)nitrosomethanide (cmnm), obtained from the in situ nucleophilic addition of MeOH to dicyanonitrosomethanide (dcnm). X-ray crystallographic studies show that the complex [Mn II 3 (cmnm) 6 ]·MeOH ( 1 ) is a linear trinuclear species, with a central octahedral and two outer trigonal-prismatic manganese(II) ions. Two mixed-valent tetranuclear complexes [Mn II 2 Mn III 2 O 2 (cmnm) 4 Cl 2 (MeOH) 6 ] ( 2 ) and [Mn II 2 Mn III 2 O 2 (cmnm) 4 Cl 2 (MeOH) 4 (pzH) 2 ]·2MeOH ( 3 ) (pzH = pyrazole) contain two Mn II and two Mn III ions in butterfly-type structures, with the six-coordinate ‘body’ Mn III ions bridged to the seven-coordinate ‘wingtip’ Mn II ions by μ 3 -O 2− and by nitroso oxygen atoms of the cmnm ligands. The formation of the trinuclear and tetranuclear manganese clusters is dependent on the stoichiometry used in the reactions. Solid state DC magnetic susceptibility studies on complexes 1 and 3 reveal that antiferromagnetic interactions are dominant within the clusters. Fits of the data reveal an S = 5 / 2 ground state for 1 and a S = 0 ground state for 3 , with several close lying excited states found in both cases.

A long and highly flexible internally functionalized dipyridyl ligand α,α'-p-xylylenebis(1-(4-pyridylmethylene)-piper-4-azine), L, has been employed in the synthesis of a series of coordination polymer materials with Co(II), Cd(II), and Ag(I) ions. In poly-[Cd(L)(TPA)] 1 and poly-[Co(L)(IPA)], 2, (TPA = terephthalate, IPA = isophthalate) the ligand adopts a similar linear conformation to that seen in the structure of the unbound molecule and provides a long (2.6 nm) metal-metal bridging distance. Due to the mismatch of edge lengths with that provided by the carboxylate coligands, geometric distortions from the regular dia and (4,4) network geometries for 1 and 2, respectively, are observed. In poly-[Ag2(CF3SO3)2(L)], 3, the ligand coordinates through both pyridine groups and two of the four piperazine nitrogen donors, forming a high-connectivity 2-dimensional network. The compound poly-[Ag2(L)](BF4)2·2MeCN, 4, a porous 3-dimensional cds network, undergoes a fascinating and rapid single-crystal-to-single-crystal rearrangement on exchange of the acetonitrile guests for water in ambient air, forming a nonporous hydrated network poly-[Ag2(L)](BF4)2·2H2O, 5, in which the well-ordered guest water molecules mediate the rearrangement of the tetrafluoroborate anions and the framework itself through hydrogen bonding. The dynamics of the system are examined in greater detail through the preparation of a kinetic product, the dioxane-solvated species poly-[Ag2(L)](BF4)2·2C4H8O2, 6, which undergoes a slow conversion to 5 over the course of approximately 16 h, a transition which can be monitored in real time. The reverse transformation can also be observed on immersing the hydrate 5 in dioxane. The structural features and physical properties of each of the materials can be rationalized based on the flexible and multifunctional nature of the ligand molecule, as well as the coordination behavior of the chosen metal ions.

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.

The dicyanonitrosomethanide (dcnm) ligand undergoes an in situ transition metal promoted nucleophilic addition of methanol to a nitrile group to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) in the formation of the 3d/4f heterometallic complexes (Me4N)[{Ni(cmnm)3}2Ln(cmnm)2] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm). A change in the counter-ions of the metal and ligand salts employed under alternate reaction conditions results in the formation of (Et4N)2[{Ni(cmnm)3}2Ln(dcnm)2](ClO4) (2Ln; 2Ln = 2La, 2Ce), in which unreacted dcnm ligands are coordinated to the central lanthanoid. In both types of complexes three cmnm ligands chelate to a nickel metal centre to form a [Ni(cmnm)3] metalloligand. Two of these metalloligands are then bound to a central lanthanoid via the nitroso oxygen atoms, resulting in a trinuclear complex in which each nickel cation is connected to the lanthanoid by three bridging nitroso groups. Variable temperature magnetic susceptibilities on these {Ni(S = 1), Ln(f0 to f5), Ni(S = 1)} spin systems reveal very weak to zero Ln–Ni or Ni–Ni exchange coupling with the thermal depopulation between Stark levels on the Ln centres being of similar magnitude, and the Ni2Ce and Ni2Pr cases giving strongest evidence for exchange coupling.

A cobalt(II) coordination polymer, [Co(L1)(H2L2)]·2.5H2O, 1, has been prepared via the hydrothermal reaction of cobalt(II) chloride with the novel dicarboxy-Troger’s base ligand 2,8-dicarboxy-6H,12H-5,11-methano-dibenzo[b,f][1,5]diazocine, H2L1, and the bis-pyrazole ligand 4,4′-methylenebis-(3,5-dimethylpyrazole), H2L2. The structure of 1 contains 2D (4,4) networks showing 2D → 3D parallel interpenetration, whereby adjacent 2D sheets interlock through the apertures defined by the cleft-like Troger’s base ligand, to realise an overall 3D entanglement. The interlocking also forms one-dimensional solvent filled channels which are easily disturbed on drying resulting in framework collapse. The crystal structure of H2L1 is also reported, and represents a rare example of homochiral hydrogen bonded [6,4] dia networks interpenetrated by their enantiomeric partner frameworks.

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.

A 3-fold interpenetrating porous metal–organic framework, namely, Zn(bdc)(L)·solvents (1, L = N4,N4′-di(pyridin-4-yl)biphenyl-4,4′-dicarboxamide, H2bdc = terephthalic acid), composed of self-catenated nets with unprecedented hxg-d-4-Fddd topology is reported. Upon removal of guest molecules, the crystal lattice is unaffected, and the resulting permanent porosity can be applied for gas chromatography separation of various organic molecules. Furthermore, remarkable tunable photoluminescence and direct white emission dependent on excitation wavelength, as well as visible light photocatalytic activity, are also observed, creating a new multifunctional material antetype.

The synthesis, structure and magnetic property of a new coordination network {[Co2(bcp)2(bpt)2]·2H2O}n (1) (H2bcp = 1,3-bis(4-carboxy-phenoxy)propane and bpt = 2,5-bis(4-pyridyl)-1,3,4-thiadiazole), is reported. Complex 1 shows a 3D 48.66.8 topology with unusual self-penetration, in which represents a new example of 6-connected networks. In addition, the magnetic property of 1 has also been investigated.

Four new dipyridylamino-substituted s-triazine ligands DBB (N(2),N(2),N(4),N(4)-tetrabenzyl-N(6),N(6)-di(pyridin-2-yl)-1,3,5-triazine-2,4,6-triamine), DDB (N(2),N(2),N(4),N(4)-tetrabutyl-N(6),N(6)-di(pyridin-2-yl)-1,3,5-triazine-2,4,6-triamine), DCCl (6-chloro-N(2),N(2)-dicyclohexyl-N(4),N(4)-di(pyridin-2-yl)-1,3,5-triazine-2,4-diamine) and DDT (N(2),N(2),N(4),N(4)-tetraphenyl-N(6),N(6)-di(pyridin-2-yl)-1,3,5-triazine-2,4,6-triamine), have been incorporated into eight new, 0D Fe(II) compounds of type [Fe(II)(NCX)(2)(L)(2)]·Solvent (where NCX = NCS(-), NCSe(-) or N(CN)(2)(-)). The polymorphic compounds α-trans-[Fe(II)(NCS)(2)(DBB)(2)] (1) and β-trans-[Fe(II)(NCS)(2)(DBB)(2)] (2) display, respectively, a relatively abrupt, complete, one-step spin transition with T(½) ~ 170 K, and a more gradual, complete, one-step spin transition with T(½) ~ 300 K. Gradual, one-step spin transitions are observed for trans-[Fe(II)(N(CN)(2))(2)(DBB)(2)]·2CH(3)CH(2)OH (3) and trans-[Fe(II)(NCSe)(2)(DCCl)(2)]·2CH(3)OH (6) with T(½) ~ 280 K for both, while the one-step spin transition observed for a desolvated sample of trans-[Fe(II)(NCSe)(2)(DDB)(2)]·2CH(3)OH (4) is relatively abrupt, showing hysteresis with T(½↑) = 285 K and T(½↓) = 275 K. The compounds cis-[Fe(II)(NCS)(2)(DDB)(2)] (5) and trans-[Fe(II)(NCS)(2)(DDT)(2)]·4CH(2)Cl(2) (7) remain high spin, while structural data on trans-[Fe(II)(NCSe)(2)(DDT)(2)]·4CH(2)Cl(2) (8) suggests a spin transition at low temperatures. It is likely that distortion of the Fe(II)N(6) octahedron, intermolecular interactions and molecular conformation are crucial in deciding both the T(½) and abruptness of the spin transition for these species, although the nature of their influence varies. Variable temperature powder X-ray diffraction measurements on the polymorphs 1 and 2 reveal anisotropy in the unit cell parameters as the spin transition occurs.

An equimolar mixture of Ni(NO3)2·6H2O and pyridine-2-aldehyde with two equivalents of NaN3 in methanol in the presence of NaOMe resulted in the formation of light green precipitate which upon crystallization from dimethylformamide (DMF) yielded light green single crystals [{Ni2Na2(pic)4(N3)2(H2O)2(MeOH)}· MeOH·3H2O]n (1) and [{Ni2Na2(pic)4(N3)2(H2O)4}·2DMF·H2O]n (2) (pic = pyridine-2-carboxylate) at room temperature and high temperature (100°C), respectively. Variable temperature magnetic studies revealed the existence of overall ferromagnetic behaviour with J ≈ +10 cm − 1 and D ≈ − 2 to −7 cm − 1 for 1 and 2, respectively. Negative D values as well as variation of D upon slight distortion of structure by varying reaction temperature were observed. The X-band Electron Paramagnetic Resonance (EPR) spectra of both 2 and 3 were recorded below 50 K. The structural distortion was also implicated from the EPR spectra. Density Functional Theory (DFT) calculations on both complexes were performed in two different ways to corroborate the magnetic results. Considering only Ni\(^{\rm II}_{2}\) dimeric unit, results were J = +20.65 cm − 1 and D = −3.16 cm − 1 for 1, and J = +24.56 cm − 1 and D = −4.67 cm − 1 for 2. However, considering Ni\(^{\rm II}_{2}\)Na\(^{\rm I}_{2}\) cubane as magnetic core the results were J = +16.35 cm − 1 (1), +19.54 cm − 1 (2); D = −3.05 cm − 1 (1), −4.25 cm − 1 (2).

A novel hexanuclear complex [{(CuL)2Cu}2(μ-dca)2](ClO4)2·2L′(1) (where H2L = (OH)C6H4C(CH3) N(CH2)3N C(CH3)C6H4(OH) or N,N′-bis(2-hydroxyacetophenone) propylenediimine and dca = N(CN)2− and L′ = 2-hydroxyacetophenone) has been synthesized and characterized by elemental analysis, UV–Vis, FT-IR spectroscopic and electrochemical methods. Single crystal X-ray structural characterization reveals a centrosymmetric nature of the complex unit, where the metal centers adopt distorted square-planar and distorted octahedral geometries. Structural analysis also reveals μ2-phenoxo bridges between terminal and the central copper(II) centers of the asymmetric [(CuL)2Cu(dca)] unit, the latter being interconnected to its symmetry related counterpart by double μ1,5-dca bridges, leading to the hexanuclear complex ion [{(CuL)2Cu}2(μ-dca)2]2+. Low temperature susceptibility measurements of 1 revealed the presence of strong antiferromagnetic coupling (2J = −407 cm−1) between the copper(II) centers.

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.

In this work the nucleophilic addition of water and methanol to the dicyanonitrosomethanide anion (dcnm, [C(CN)(2)(NO)](-)) in the absence of the usual transition metal promoters was investigated. Experimentally it was shown that a quantitative conversion of the dcnm anion to carbamoylcyanonitrosomethanide (ccnm, [C(CN)(CONH(2))(NO)](-)) by the addition of 1 equiv of water to a nitrile group is complete in 48 h at 100 °C, or in 1.5 h at 150 °C when the reaction is conducted in a microwave reactor. Attempts to add a second equivalent of water to the anion failed with thermal degradation of the anion occurring at 200 °C. Ab initio calculations show that the reaction proceeds via three distinct transition states: (1) the transfer of a proton from a water molecule to the nitrile group, (2) the subsequent attack of the generated hydroxide anion on the carbon atom of the nitrile group, and (3) a rapid proton transfer to form a carbamoyl group. The attacking water molecule is shown to be a stronger proton donor when modeled as part of a hydrogen-bonded three water molecule chain, leading to a significant reduction in the reaction barrier. Only the anti-ccnm anion is formed in the reaction. There is a high-energy barrier to the formation of the syn isomer by the rotation of the nitroso group. While the syn isomer of ccnm is shown to be the more thermodynamically stable conformation, examination of the HOMO-1 molecular orbital that arises during the second transition state of the reaction indicates the addition of the hydroxide anion to the carbon atom is forbidden due to orbital symmetry, with a similar effect responsible for the failure of a second equivalent of water to add to the ccnm anion. Under analogous reaction conditions the addition of 1 equiv of methanol to dcnm to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm, [C(CN)(C(OMe)NH)(NO)](-)) failed, although ab initio calculations initially indicated the reaction should proceed more readily than the addition of water. When the energy required to break the hydrogen-bonded cyclic hexamers in methanol is taken into consideration, the energy barrier to the first transition step is greatly increased. The addition of a second equivalent of methanol to cmnm is unlikely to occur even in the presence of a transition metal as the resultant anion would be marginally thermodynamically unstable.

A fascinating 3D entangled metal-organic framework, namely, {[Co(2)(bcp)(2)]·3H(2)O}(n) (1), was obtained through the solvothermal generation of flexible and long dicarboxylate (bcp) and metal salt. The crystal structure contains a 1D metal chain with bcp ligands wrapped around it in a wavy line and features an unusual entangled topological net. Furthermore, the magnetic behavior of 1 was also studied and indicated the existence of ferromagnetic interaction and long-range ordering character.