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Naphthalene derived compounds that belong to the polycyclic aromatic hydrocarbons have significant importance in medicinal chemistry owing to their interesting biological activities. The structural knowledge of new naphthalene derived compounds can help in the understanding of their mechanism of action. In this study, we have investigated the molecular and structural landscape of three naphthalene-derived dications, namely, 1,1′-(naphthalene-2,6-diylbis(methylene))bis(3-methyl-1H-imidazolium), 1,1′-(naphthalene-2,7-diylbis(methylene))bis(3-methyl-1H-imidazolium) and 1,1′-(naphthalene-2,6-diylbis(methylene))bis(1-butylpyrrolidinium) as bromide salts. The structural details and non-covalent interactions for these structures were carefully examined using X-ray crystallography. Contributions to crystal packing from various types of intermolecular contacts were investigated and quantified using the Hirshfeld surface analysis. The backgrounds of these differences were analysed in terms of the key factors such as hydrogen bonding, the position of substituents appended on the naphthyl ring, and the presence of aromatic and non-aromatic moieties as substituents. The present work not only demonstrates how the position of the substituent group on the bicyclic ring influences the geometric conformation and overall packing, but also contributes toward a better understanding of how molecules self-assemble with respect to different functional groups (aromatic vs. non-aromatic). [ABSTRACT FROM AUTHOR]

Four multi-component complexes based on p-sulfonatocalix[4]arene anion, the methyltriphenylphosphonium cation, lanthanide ions (Gd(III)) and different ionic liquid-based cations (1-methyl-3-butylimidazolium, 1-methyl-3-octylimidazolium and 1,4-bis((3-methylimidazolidinyl)methyl)benzene) were synthesised and structurally characterised. Common bilayer arrangements are formed in the extended structures of all four complexes, though the bilayer thicknesses varies depending on the components involved. Molecular capsule formation is facilitated by the inclusion of methyltriphenylphosphonium, 1-methyl-3-butylimidazolium and 1,4-bis((3-methylimidazolidinyl)methyl)benzene cations, but not in the case of the 1-methyl-3-octylimidazolium cation. Molecular capsule size depends on the nature of the included guest cation, and methyltriphenylphosphonium cations fill compact spaces between calixarenes in these new bilayer arrays. [ABSTRACT FROM AUTHOR]

Structural studies on p-sulfonatocalix[4]arene coordination compounds involving diverse metal ions with respect to their size and charge, caesium(I), copper(II) and neodymium(III) are reported. The metal coordination-driven self-assembly forms metallosupramolecules, either as a two-dimensional (2 D) or a three-dimensional (3D) network while retaining the commonly established bilayer array for p-sulfonatocalix[4]arene. The complex (Cs5-p-sulfonatocalix[4]arene-H+)·6H2O has five crystallographically independent caesium(I) ions with high coordination numbers. In the divalent complex {[Cu3(H2O)12-2(p-sulfonatocalix[4]arene)]2-}·2([Cu(H2O)5])2+·2NO3-·7H2O, two different copper(II) coordination environments are present, one with octahedral stereochemistry while bridging two opposing calixarenes with the other having a square pyramidal geometry involving one sulfonate group. Eight-coordinate neodymium(III) metal ions prevail in Nd0.25(H2O)1.25(p-sulfonatocalix[4]arene + H+)0.25, involving four sulfonate groups from four different calixarenes. [ABSTRACT FROM AUTHOR]

Two multi-component crystal structures comprising a carboxylic acid-functionalized imidazolium zwitterion, a p-sulfonatocalix[4]arene anion and aquated metal ion (Na+ or Y3+) with or without an auxiliary component (the 3-methoxyphenyl-triphenylphosphonium cation) are reported. The carboxylic acid-functionalized imidazolium ion binds either as a monodentate or a bidentate ligand depending on the nature of the metal ions, and a bi-layer arrangement prevails in the extended structure regardless of the type of metal ion employed or presence/lack of auxiliary component. [ABSTRACT FROM AUTHOR]

Trinuclear lanthanoid clusters have been synthesised and investigated as toroidal spin systems. A pyridyl functionalised β-diketonate, 1,3-bis(pyridin-2-yl)propane-1,3-dione (o-dppdH) has been used to synthesise a family of clusters of the form [Dy3(OH)2(o-dppd)3Cl2(H2O)4]Cl2·7H2O (1), [Tb3(o-dppd)3(μ3-OH)2(CH3CH2OH)3Cl3][Tb3(o-dppd)3(μ3-OH)2(H2O)(CH3CH2OH)2Cl3]Cl2·H2O (2), [Ho3(OH)2(o-dppd)3Cl(H2O)5]Cl3·3H2O (3) and [Er3(OH)2(o-dppd)3Cl2(H2O)3(CH3OH)]Cl2·3H2O·CH3OH (4). Despite the previous occurrence of this structural motif in the literature, these systems have not been widely investigated in terms of torodic behaviour. Magnetic studies were used to further characterise the complexes. DC susceptibility studies support weak antiferromagnetic exchange in the complexes. Slow magnetic relaxation behaviour is observed in the dynamic AC magnetic studies for complex 1. Theoretical studies predict that complex 1 and 3 have a non-magnetic ground state based on a toroidal arrangement of spins. Changes to the coordination environment in 2 do not support a toroic spin state. The prolate nature of the ErIII centres in complex 4 and large transverse anisotropy do not support the toroidal arrangement of lanthanoid spins in the complex. [ABSTRACT FROM AUTHOR]

The organisation of the p-xylylenebis(triphenylphosphonium) dication in the solid state, in crystals formed under a variety of conditions, at different pH values and in the presence of THF and other potential building moieties including p-sulfonatocalix[4]arene, 1-methyl-3-butylimidazolium and aquated gadolinium(III) has been investigated using single crystal X-ray diffraction studies. Striking changes in the dication conformations (cis- and trans-) that contribute to the different crystal packings of the dication (two-dimensional layerings and three-dimensional scaffoldings) have been established for five different compounds. The interplay and the self-assembled arrays of the dication with other incorporated components and the overall non-covalent interactions have been quantified using Hirshfeld surface analyses. [ABSTRACT FROM AUTHOR]

Nine multipodal cationic molecules with adaptable cyclic and acyclic amine functional groups along with bromide as the counterion have been synthesised and structurally characterised by single crystal X-ray diffraction. In the solid-state, the dicationic bipodal molecule has a pincer-like geometry while the tricationic tripodal molecule has a cavity-like geometry. The tetracationic tetrapodal molecule crystallised as the chair conformer as a result of steric crowding by the heterocyclic amine functional groups (imidazolium and pyrrolidinium), which prohibits arrangement of the heterocyclic amine substituents in the same direction. This study also illustrates that the different packing motifs (including linear and corrugated layers, and channels) are affected by the substituents at the central core for each type of multipodal molecule. CrystalExplorer was used to visualise these weak intermolecular interactions and to quantitatively summarise the interactions that contribute to the overall stability to the crystal structure. [ABSTRACT FROM AUTHOR]

The interplay of organic dications bearing various n-alkylimidazolium termini substituted at different positions on a bis(methylene)phenyl ring and p-sulfonatocalix[4]arene, along with tetraphenylphosphonium cations and hydrated lanthanides (Ce3+, Er3+ and Gd3+), afforded various self-assembled solid-state structures. The host–guest binding behaviour of the dications and p-sulfonatocalix[4]arene was carefully investigated by crystallographic studies including their interactions in the solution state, but in the absence of phosphonium and lanthanide cations via1H NMR experiments. [ABSTRACT FROM AUTHOR]

β-Triketonates have been recently used as chelating ligands for lanthanoid ions, presenting unique structures varying from polynuclear assemblies to polymers. In an effort to overcome low solubility of the complexes of tribenzoylmethane, four β-triketones with higher lipophilicity were synthesised. Complexation reactions were performed for each of these molecules using different alkaline bases in alcoholic media. X-ray diffraction studies suggested that the ligands were undergoing decomposition under the reaction conditions. This is proposed to be caused by in situ retro-Claisen condensation reactions, consistent with two examples that have been reported previously. The lability of the lanthanoid cations in the presence of a varying set of potential ligands gave rise to structures where one, two, or three of the molecules involved in the retro-Claisen condensation reaction were linked to the lanthanoid centres. These results, along with measurements of ligand decomposition in the presence of base alone, suggest the solvent used will modulate the impact of the retro-Claisen condensation in these complexes. [ABSTRACT FROM AUTHOR]

Isomorphous β-triketonate-based lanthanoid polymers containing tris(4-methylbenzoyl)methanide (mtbm) and Rb+ with formula {[Ln(Rb)(mtbm)4]2}n (Ln = Eu3+ and Nd3+) have been synthesised and structurally characterised. The photophysical properties for the Nd3+ complex presented relatively long lifetimes and high quantum yields in comparison with analogous β-diketonate complexes. Mixed lanthanoid complexes were also formed and their luminescence properties studied, with effective sensitisation of the 4F3/2 of Nd3+via the 5D0 of Eu3+, which is to the best of our knowledge the first example of Eu3+ to Nd3+ sensitisation in a structurally defined coordination complex or polymer. [ABSTRACT FROM AUTHOR]

A molecular capsule based on two p-sulfonated calix[4]arenes along with Gd(iii) coordination spheres arranged around the equator of the capsule effectively confined a 1-butyl-3-methylimidazolium cation, affording a relatively small capsule size. For a bis-imidazolium cation, only one of the imidazole rings is included in the calixarene cavity with the other ring extending towards a sulfonate group of an adjacent calixarene. Thus, the included molecule breaches the equatorial seam of the larger capsule, but here there is no incorporation of Gd(iii). In both complexes the capsules themselves are arranged such that the calixarenes are in bilayer arrangements, with (3-methoxyphenyl)triphenylphosphonium cations at the interface of the hydroxyl groups of the calixarene. The interplay of the components was also investigated using Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Broad-band near-infrared (NIR) transient absorption (TA) spectroscopy has been used for the first time to probe an all-carbon-bridged organometallic radical cation complex. The compound [{Ru(PPh3)2Cp}2(µ-CCCC)]+ ([1]+) was investigated in dichloromethane and acetonitrile solutions, using laser excitation at 700, 800, 900, and 1000 nm; these wavelengths span the NIR absorption band envelope. The resulting TA spectra were found to be independent of excitation wavelength and consist of an excited state absorption feature with a peak at ca. 1150 nm and the corresponding bleach signal of the ground-state NIR absorption band, which both decay to 0 over the 50 ps time window investigated. Data were analyzed globally and fit collectively for each of the four different excitation wavelengths, with the resulting best fit to a biexponential decay function indicating two processes with slightly different time scales of ca. 1.5 and ca. 9.0 ps involved in the relaxation to the ground state. [ABSTRACT FROM AUTHOR]

Long flexible bis-imidazolium dications form discrete multi-component complexes with anionic p-sulfonatocalix[4]arene, cationic tetraphenylphosphonium, and hydrated lanthanide ions (La3+ and Gd3+). The terminally charged head groups of the dications reside in either one or two calixarene cavities of different bilayers depending on the length of the terminal alkyl group with the central spacer penetrating across the multi-layers and adjusted to fit in the tight bilayer. [ABSTRACT FROM AUTHOR]

After a long history of use as a prototype cysteine protease inhibitor, the crystal structure of loxistatin acid (E64c) is finally determined experimentally using intense synchrotron radiation, providing insight into how the inherent electronic nature of this protease inhibitor molecule determines its biochemical activity. Based on the striking similarity of its intermolecular interactions with those observed in a biological environment, the electrostatic potential of crystalline E64c is used to map the characteristics of a pseudo-enzyme pocket. [ABSTRACT FROM AUTHOR]

Solution mediated organization of p-sulfonatocalix[4]arene, benzyltriphenylphosphonium cations, and bis(triethylammoniomethyl)-benzene dications in the solid state results in the ammonium dications preferentially binding in the cavities of two opposing calixarenes which take on a −3 charge, with the phosphonium cations arranged in a separate 2D sheet relative to the calixarene bilayer. [ABSTRACT FROM AUTHOR]

Structure determinations for some Co(III) complexes of simple derivatives of the cage hexamine 3,6,10,13,16,19-hexa-azabicyclo[6.6.6]icosane ("sarcophagine") show that there is no evidence that the H-bonding involving the NH centres of the complex cations is influenced by electronic effects due to the substituents. "H-bond chelation" of chloride anions or water molecules results in retention of the symmetrical lel3 conformation. [ABSTRACT FROM AUTHOR]

Large metal—oxo clusters consistently assume spherical or regular polyhedral morphologies rather than high-aspect-ratio structures. Access to elongated core structures has now been achieved by the reaction of lanthanoid salts with a tetrazole-functionalized calixarene in the presence of a simple carboxylate coligand. The resulting Ln19 and Ln12 clusters are constructed from apex-fused Ln5O6 trigonal bipyramids and are formed consistently under a range of reaction conditions and reagent ratios. Altering the carboxylate coligand structure reliably controls the cluster length, giving access to a new class of rod-like clusters of variable length. [ABSTRACT FROM AUTHOR]

The modification of conjugated organic compounds with organometallic moieties allows the modulation of the electronic and optoelectronic properties of such compounds and lends them to a variety of material applications. The organometallic complexes [M(Cp′)(L) n ] (M = Ru or Fe; Cp′ = cyclopentadiene (Cp) or pentamethylcyclopentadiene (Cp*); (L) n = (PPh3)2 or 1,2-bi(diphenylphosphino)ethane (dppe)) and [M(L) n ] (M = Ru; (L) n = (dppe)2 or (P(OEt)3)4; or M = Pt; (L) n = (PEt3)2, (PPh3)2 or tricyclohexylphosphine, (PCy3)2) modified with a 5-ethynyl-1,3,3-trimethyl-3 H -indole ligand were prepared and characterised by NMR spectroscopy, IR and single-crystal X-ray diffraction. Cyclic voltammetry and IR spectroelectrochemistry of the ruthenium systems showed a single-electron oxidation localised over the M–C≡C–aryl moiety. The N-heteroatom of the indole ligand showed Lewis base properties and was able to extract a proton from a vinylidene intermediate as well as coordinate to CuI. Examples from the wire-like compounds were also studied by single-molecule break junction experiments but molecular junction formation was not observed. This is most likely attributable to the binding characteristics of the substituted terminal indole groups used here to the gold contacts. A series of organometallic σ-alkynyl complexes incorporating the 3 H -indole moiety were designed and synthesised. The complexes were studied using electrochemical and spectroelectrochemical techniques. The N-heteroatom of the indole ligand showed Lewis base properties and could extract a proton from a vinylidene intermediate and coordinate to CuI. [ABSTRACT FROM AUTHOR]

Herein we describe the design and preparation of inexpensive, air-stable nickel phosphite-based catalysts for use in the CN cross-coupling reaction. The combination of nickel tetrakis(triphenyl phosphite) {Ni[P(OPh)3]4} and 1,1′-bis(diphenylphosphino)ferrocene (dppf), and in particular a newly developed catalyst (dppf)Ni[P(OPh)3]2, were found to be extremely effective in catalyzing a range of amination reactions of anilines and amines with aryl chlorides. This new catalyst system offers an alternative to the bis(cyclooctadienyl)nickel [Ni(COD)2] and palladium(0) catalysts commonly used for CN bond formation. [ABSTRACT FROM AUTHOR]

Singlecrystal X-ray diffraction data measured at 100 K for Dianin’scompound (DC) and 18 of its clathrates formed with a wide range ofguest molecules provide considerable insight into the way the hostadjusts to accommodate guest molecules. Detailed information is alsoobtained regarding the location, orientation, and dynamics of theguests in the host cavity. Although all unit cells are closely similarin size, the host undergoes significant change in response to theimprisonment of its various guests. Enclathration typically resultsin a larger cell and cavity volume, but for the small molecules methanol,ethanol, and nitromethane the host actually shrinks significantlyaround the guests in the cavity. In most clathrates, there is evidenceof close contacts between atoms in the guest and the phenol −OHgroup and/or ring of the DC host. The series of clathrates formedby benzene, toluene, and the halobenzenes show the orientation ofthe benzene ring to be progressively modifed by the increasing sizeof the substituent atom or group on the ring in a systematic mannerthat reflects functional group contributions to van der Waals volumes. [ABSTRACT FROM AUTHOR]

A single crystal of 3,5-di-tert-butylpyrazole has been the subject of structure determinations at 10, 100, 120 and 299 K. Above ∼ 110 K, the structure is Pbca, a ≈ 11.3, b ≈ 20.6, c ≈ 10 Å, Z = 8. Below 110 K, the c axis is doubled and the space group becomes Pb21a, Z = 16. Here the asymmetric unit is comprised of four molecules, arranged as a pair of overlapping hydrogen-bonded dimers, all components being ordered. In each case one methyl group of each t-butyl group lies coplanar with its parent pyrazole ring and, within each quasi-inversion-related dimer, one molecule has both of these methyl groups directed away from the N2 component ‘cis’, while in the other, one methyl group is toward (‘trans’). Above 110 K the four molecules collapse into one, with one t-butyl group (corresponding to an overlaid ‘cis/trans’ pair of the low-temperature form) modelled as disordered. The disorder has been previously described as ‘temperature dependent’ (Deacon et al, 2001), but the present studies suggest it to be dependent on the history of the particular specimen as well. [ABSTRACT FROM AUTHOR]

The crystal structures of the Tutton salts (NH4)2-[Cu(H2O)6(SO4)2, diammonium hexaaquacopper disulfate, formed with normal water and isotopically substituted H218O, have been determined by X-ray diffraction at 9.5 K and are very similar, with Cu-O(7) the longest of the Cu-O bonds of the Jahn-Teller distorted octahedral [Cu(H2O) 6]2+ complex. It is known that structural differences accompany deuteration of (NH4)2[Cu(H2O) 6](SO4)2, the most dramatic of which is a switch to Cu-O(8) as the longest such bond. The present result suggest that the structural differences are associated with hydrogen-bonding effects rather than with increased mass of the water ligands affecting the Jahn-Teller coupling. The Jahn-Teller distortions and hydrogen-bonding contacts in the compounds are compared with those reported for other Tutton salts at ambient and high pressure. [ABSTRACT FROM AUTHOR]

Four ternary multi-component crystal structures comprising water-soluble p-sulfonatocalix[4]arene anion as the cavitand in the presence of different types of positively charged guest molecules comprising 1-butylimidazolium, 3,3′-(1,4-phenylenebis(methylene))bis(1-methylimidazolium), 3,3′,3′′-(benzene-1,3,5-triyltris(methylene))tris(1-methylimidazolium), or 3,3′,3′′,3′′′-(benzene-1,2,4,5-tetrayltetrakis(methylene))tetrakis(1-methylimidazolium) and aquated lanthanide(III) ions (Gd(III) or Ce(III)) are reported. Careful crystallographic analysis shows that all positively charged imidazole rings are encapsulated by p-sulfonatocalix[4]arene for 1-butylimidazolium and 3,3′-(1,4-phenylenebis(methylene))bis(1-methylimidazolium), however, partial encapsulation was observed for 3,3′,3′′-(benzene-1,3,5-triyltris(methylene))tris(1-methylimidazolium) and 3,3′,3′′,3′′′-(benzene-1,2,4,5-tetrayltetrakis(methylene))tetrakis(1-methylimidazolium). The formation of a molecular capsule prevails in all structures regardless of the type of guest species. Supermolecules in three of the complexes self-assemble into a bilayer arrangement in the extended structure, whilst those involving p-sulfonatocalix[4]arene and 1-butylimidazolium form hydrated channels through alternative packing. [ABSTRACT FROM AUTHOR]

Morpholine motifs have been used extensively as targeting moieties for lysosomes, primarily in fluorescence imaging agents. Traditionally these imaging agents are based on organic molecules which have several shortcomings including small Stokes shifts, short emission lifetimes, and susceptibility to photobleaching. To explore alternative lysosome targeting imaging agents we have used a rhenium based phosphorescent platform which has been previously demonstrated to have an improved Stokes shift, a long lifetime emission, and is highly photostable. Rhenium complexes containing morpholine substituted ligands were designed to accumulate in acidic compartments. Two of the three complexes prepared exhibited bright emission in cells, when incubated at low concentrations (20 μM) and were non-toxic at concentrations as high as 100 μM, making them suitable for live cell imaging. We show that the rhenium complexes are amenable to chemical modification and that the morpholine targeted derivatives can be used for live cell confocal fluorescence imaging of endosomes–lysosomes. [ABSTRACT FROM AUTHOR]

Eight organic salts made up of two different organic phosphonium monocations, tetraphenylphosphonium or benzyltriphenylphosphonium, and common anions of different shape, size and charge distribution have been structurally authenticated. The crystal packing for the tetraphenylphosphonium cations involves one-dimensional infinite stacked columns incorporating translational quadruple embraces (TQPE) regardless of the type of counter ion. As for benzyltriphenylphosphonium salts, different packing arrays were obtained with different anions. Interestingly, the anions control the intermolecular packing of the same phosphonium cation, while hydrogen bonding is found to be the dominant contributor in the overall self-assembly. Hydrophobic interactions between the phosphonium cations driven by the phenyl–phenyl embrace involving π⋯π and/or C–H⋯π interactions also contribute to the cohesion of the structures. Charge-assisted hydrogen bonding and halogen bonding were also evident, which are relatively strong compared to classical hydrogen bonds, as judged from the short intermolecular distances. The interactions have also been quantified using Hirshfeld surfaces analyses. [ABSTRACT FROM AUTHOR]

Structurally authenticated complexes of the cone-shaped p -sulfonatocalix[4]arene and conformationally flexible p -sulfonatocalix[6]arene devoid of co-ligands/ancillary molecules are limited. Early and late members of the lanthanide series as their trivalent ions, La3+, Er3+, and Yb3+, form complexes from aqueous media under these conditions. For La3+ and Er3+, distinct hydrophobic and hydrophilic bilayers are formed with p -sulfonatocalix[4]arene, whereas for Yb3+, two complexes form that deviate from the well-known bilayer arrangement of calixarenes. Replacing the calixarene with p -sulfonatocalix[6]arene results in a hydrogen-bonded network with alternating hydrophobic–hydrophilic layers associated with primary coordination of Yb3+, with the larger macrocyclic calixarene in a partial cone conformation. Bilayers are created when cone-shaped p -sulfonatocalix[4]arene forms complexes with La3+ and Er3+, whereas with Yb3+ overall assembly deviates from the bilayer arrangement. With conformational flexible p -sulfonatocalix[6]arene, this results in a hydrogen bonded network with alternating hydrophobic-hydrophilic layers associated with primary coordination of Yb3+, with the calixarene crystallised in a partial cone conformation. [ABSTRACT FROM AUTHOR]

The title compounds [(Ph3As)2AuI] and [(Ph3As)3AuI] have been crystallized from equimolar solutions of Bu4NAuI2 and AsPh3 in dimethylformamide and structurally characterized by single crystal X-ray diffraction studies. [(Ph3As)2AuI] crystallizes in space group C 2/ c , Z 4, and is isomorphous with other [(Ph3E)2MX] (MX = coinage metal(i) salt) arrays, with the Au–I bond being disposed on a crystallographic 2-axis: Au–I, As 2.7008(2), 2.4337(2) Å, As–Au–As, I 125.736(8)°, 117.132(4)° (153 K). [(Ph3As)3AuI] crystallizes as a triclinic phase in space group CH19340_IE1.gif , Z 4, and is isomorphous with [(Ph3Sb)3CuI] and [(Ph3P)3AgI]: Au–As 2.4847–2.5049(10), Au–I 2.8518(8), 2.8597(7) Å with As–Au–As, I 109.67(3)–115.97(3)°, 101.33(2)–106.85(3)°. A second '[(Ph3As)3AuI]' product was obtained as a co-crystalline phase in space group P 21/ n containing [(Ph3As)3AuI], and [(Ph3As)2AuI] accompanied by an additional unbound Ph3As molecule, i.e. [(Ph3As)3AuI]·[(Ph3As)2AuI·Ph3As], with structural parameters closely similar to those for the corresponding separate [(Ph3As)3AuI] and [(Ph3As)2AuI] complexes described above. Comparison of the bond lengths for these and related complexes show that they are generally consistent with the 'gold is smaller than silver' phenomenon caused by relativistic orbital contraction effects in gold, but the results also show that the magnitude of this effect is dependent on the nature of the metal–ligand bonds involved, and on changes in the metal coordination environment, which can in some circumstances yield trends in which the effect on particular bonds is partially masked or even reversed. Comparison of the bond lengths in [(Ph3As)2AuI] and [(Ph3As)3AuI] and related complexes show that they are generally consistent with the 'gold is smaller than silver' phenomenon caused by relativistic orbital contraction effects in gold, but the results also show that the magnitude of this effect is dependent on the nature of the metal–ligand bonds involved. [ABSTRACT FROM AUTHOR]

Functionalising organic molecular photoswitches with metal complexes has been shown to alter and enhance their switching states. These organometallic photoswitches provide a promising basis for novel smart molecular materials and molecular electronic devices. We have detailed the synthesis and characterisation of mono- and bimetallic half-sandwich ruthenium and iron complexes functionalised with alkynyl dihydropyrenes (DHP). Their electronic and photophysical properties were determined by the use of chemical, electrochemical and spectroelectrochemical techniques. The introduction of the metal alkynyl moiety allows access to additional redox and protonation states not accessible by the DHP alone. An additional metal alkynyl moiety inhibits observable photochromic switching. Analysis of the NIR and IR bands in the mixed valence complexes suggests there is a high degree of charge delocalisation across the DHP. [ABSTRACT FROM AUTHOR]

The crystal structure of hexa­carbonyl­chromium(0), [Cr(CO)6], has been refined with an accurate and extensive X-ray data set collected at 11 K. This data set should be suitable for charge-density analysis studies. The structure is made up of isolated Cr(CO)6 mol­ecules of very near octahedral symmetry, containing a crystallographic mirror plane. [ABSTRACT FROM AUTHOR]

Single‐crystal X‐ray diffraction studies for a variety of metal ion complexes of functionalised sarcophagines (sarcophagine=sar=3,6,10,13,16,19‐hexa‐azabicyclo[6.6.6]icosane) have further confirmed not only that the form of the metal ion/sar unit is unique for each metal, albeit with a sensitivity of the conformation to the associated counter anions, but also that for any given metal and ligand substituent, the dimensions (bond lengths and angles) of the complex and the substituent at the secondary nitrogen centres do not differ significantly from those of the isolated components. Despite this, where the substituent contains reactive sites, the reactivity differs markedly from that of their form in an uncoordinated substrate. Rationalisations are offered for these differences, in part through the use of Hirshfeld surface analysis of the intermolecular interactions. The kinetic inertness of the complexes means that the metal ions can be considered to act as regioselective protecting groups. [ABSTRACT FROM AUTHOR]

The new Ni-catalyst is extremely effective in the amination reaction of various amines with arylchlorides and bromides. [ABSTRACT FROM AUTHOR]

New cyclophanes containing two imidazole-2-thione moieties linked by two xylylene groups have been synthesized by the reaction of imidazolium-linked cyclophanes with sulfur in the presence of K 2 CO 3 . The conformational behaviour of the new cyclophanes was explored by NMR spectroscopy and X-ray diffraction studies. In cyclophanes containing o -xylylene or 2,4,6-trimethyl- m -xylylene linking groups, the imidazole-2-thione groups were mutually syn in both the solid state and in solution, the cyclophanes adopting a conformation reminiscent of the cone conformation of calix[4]arenes. Cyclophanes containing p -xylylene or m -xylylene linking groups exhibited two conformations in solution, one in which the imidazole-2-thione groups are mutually syn , the other in which they are mutually anti , and these conformations did not interconvert on the NMR timescale. Both conformations co-crystallised in the m -xylylene linked cyclophane, while for the p -xylylene-linked cyclophane the anti conformation crystallised separately. [ABSTRACT FROM AUTHOR]

The trans-epoxysuccinyl amide group as a biologically active moiety in cysteine protease inhibitors such as loxistatin acid E64c has been used as a benchmark system for theoretical studies of environmental effects on the electron density of small active ingredients in relation to their biological activity. Here, the synthesis and the electronic properties of the smallest possible active site model compound are reported to close the gap between the unknown experimental electron density of trans-epoxysuccinyl amides and the well-known function of related drugs. Intramolecular substituent effects are separated from intermolecular crystal packing effects on the electron density, which allows us to predict the conditions under which an experimental electron density investigation on trans-epoxysuccinyl amides will be possible. In this context, the special importance of the carboxylic acid function in the model compound for both crystal packing and biological activity is revealed through the novel tool of model energy analysis. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of 5,11,17,23-tetra- tert-butyl-25-hydroxy-26,27,28-tris(tetrazol-5-ylmethoxy)calix[4]arene is reported. Purification of the macrocycle required the use of preparative HPLC techniques. The macrocycle was found to be a poorer ligand for complexation of lanthanoid cations than the bis(tetrazole) analogue, but somewhat more effective than the tetrakis(tetrazole)-substituted derivative. Two metal complexes of the tris(tetrazole)-calixarene were structurally characterised. A polymeric sodium salt of the tris(tetrazole)-calixarene was isolated from a solution containing yttrium and a sodium acetate buffer. A praseodymium complex was isolated in the presence of an ammonium acetate buffer, where the calixarene acts as a unidentate ligand, bound to the metal atom through one tetrazole N-atom. Increasing the amount of buffer resulted in the crystallisation of a metal-free ammonium salt of the calixarene. [ABSTRACT FROM AUTHOR]

The hybrid salt bis(2-methylimidazo[1,5-a]pyridin-2-ium) hexachloridostannate( IV), (C8H9N2)2[SnCl6], crystallizes in the monoclinic space group P21/n with the asymmetric unit containing an Sn0.5Cl3 fragment (Sn site symmetry 1) and one organic cation. The five- and six-membered rings in the cation are nearly coplanar; bond lengths in the pyridinium ring of the fused core are as expected; the C--N/C bond distances in the imidazolium entity fall in the range 1.337 (5)-1.401 (5) Å. The octahedral SnCl62- dianion is almost undistorted with the Sn--Cl distances varying from 2.4255 (9) to 2.4881 (8) Å and the cis Cl--Sn--Cl angles approaching 90°. In the crystal, π-stacked chains of cations and loosely packed SnCl62- dianions form separate sheets alternating parallel to (101). Most of the numerous C--H• • •Cl--Sn contacts between the organic and inorganic counterparts with the H• • •Cl distances above the van der Waals contact limit of 2.85 Å are considered a result of crystal packing. [ABSTRACT FROM AUTHOR]

Highlights: [•] [Ph3PAuX] (X=Cl, Br and I) crystallize as members of an isomorphous series in the chiral space group P212121. [•] [Ph2(Ph-CHO)PAuX] (X=Br, I) belong to the same isomorphous series. [•] [Ph2(Ph-CHO)PAuCl] crystallizes in the centrosymmetric space group . [•] The –CHO groups result in very minor differences in the conformational structures. [•] Global packing dominates while specific supramolecular interactions comply with overall crystal packing. [ABSTRACT FROM AUTHOR]

p-Sulfonatocalix[4]arenes with three of the lower rim hydroxyl groups substituted with N'-cyanocarbamimidate groups crystallizes in the 1,3-alternate conformation rather than the common cone conformation for unsubstituted calixarenes, which also results in departure from the common bilayer arrangement of sulfonated calix[4]arenes. The new calixarene formed via reaction of the phenolic moieties of the p-sulfonatocalix[4]arene with the dicyanamide anion derived from an ionic liquid with an imidazolium cation. [ABSTRACT FROM AUTHOR]

Novel complexes of form (NHC)Au(SCOR) (NHC = N‐heterocyclic carbene, SCOR− = thiocarboxylate ligand) were synthesised and characterised by spectroscopic techniques and X‐ray diffraction studies. The results of NMR and X‐ray studies indicated that thiocarboxylate ligands are comparable with NHCs in their electron donor ability. The complexes were stable at room temperature in the solid state but in solution underwent disproportionation reactions to form equilibria with [Au(NHC)2]+ and [Au(SCOR)2]−. In solution, the thiocarboxylate ligand in (NHC)Au(SCOR) underwent rapid exchange with other thiocarboxylate or thiolate ligands. The (NHC)Au(SCOR) complexes showed toxicity against cisplatin‐resistant ovarian cancer cells (OVCAR‐8), with IC50 < 10 μM, in the range exhibited by cationic [Au(NHC)2]+ complexes well‐known for their promising anticancer activity. [ABSTRACT FROM AUTHOR]

Multi-component self-assembly involving bis-phosphonium and bis-imidazolium cations, and p-sulfonatocalix[4]arene feature supermolecules based on two geometrically opposed calixarenes end-capping each bis-imidazolium cation, either with coordinated lanthanide cations or with the phosphonium cations residing around the upper rim of the calixarenes. The nature of the calixarene-bis-imidazolium interaction is mapped out using Hirshfeld surface analysis. 1H NMR and ROESY experiments establish the formation of the supermolecules of the bis-imidazolium cation and calixarenes in solution. [ABSTRACT FROM AUTHOR]

Toluene solutions of fullerene C70 and t-Bu-calix[6]arene form a 2:1 inclusion complex that has been structurally authenticated using synchrotron source X-ray diffraction data. Remarkably, the fullerene is not included in the cavity of the calixarene, and this has implications in predicting the structures of fullerene complexes of other calixarenes and container molecules. The fullerenes shroud the exo surface of the calixarene at the van der Waals limit, with the fullerenes arranged into corrugated sheets, with each calixarene interdigitated at the upper rim with the upper rim of two other calixarenes, the macrocycles forming a bilayer separating the sheets of fullerenes. Toluene solutions of fullerene C70 and t-Bu-calix[6]arene form a 2:1 solid-state inclusion complex. The fullerenes shroud the exo surface of the calixarene at the van der Waals limit, with the fullerenes arranged into corrugated sheets, with interdigitated calixarenes through the upper rims forming a bilayer between the sheets of fullerenes. [ABSTRACT FROM AUTHOR]

The single-crystal structure of a β'-copper vanadium bronze, Cu0.63V2O5, has been studied at room temperature and 9.6 K, and compared with that of the β-sodium vanadium bronze, Na0.33V2O5, structure. No convincing evidence to oppose an assignment of centrosymmetric C2/m symmetry to the structure was identified using the X-ray data. A subsequent convergent beam electron diffraction (CBED) experiment was performed and confirmed the C2/m space group. The oxygen-vanadium atom framework of Cu0.63V2O5 iS close to that of Na0.33V2O5. However, in the copper compound the Cu atoms are located in two positions: Cul in the 4(i) position with x = 0.541, y = 0 and z: 0.345, and Cu2 in the 8(j) position with x = 0.529, y = 0.038 and z: 0.357. The crystal structure changes little with temperature. Disorder of the Cu ion over two sites is seen at 9.6 K. This suggests that distribution of the Cu atoms over two sites is of a more static than dynamic nature. [ABSTRACT FROM AUTHOR]

The title compound, [Fe(C3H7NO)6][Cd2Cl7], crystallizes in the trigonal space group R3̅ and is assembled from discrete [Fe(DMF)6] 3+ cations (DMF = N,Ndimethylformamide) and [Cd2Cl7] 3- anions. In the cation, the iron(III) atom, located on a special position of 3̅ site symmetry, is coordinated by six oxygen atoms from DMF ligands with all Fe—O distances being equal [2.0072 (16) A˚ ]. A slight distortion of the octahedral environment of the metal comes from the cis O—Fe—O angles deviating from the ideal value of 90 [86.85 (7) and 93.16 (7)] whilst all the trans angles are strictly 180. The central Cl atom of the [Cd2Cl7] 3- anion is also located on a special position of 3̅ site symmetry and bridges two corner sharing, tetrahedrally coordinated CdII atoms. The two Cd atoms and the central Cl atom are colinear. The two sets of terminal chloride ligands on either side of the dumbbell-like anion are rotated relative to each other by 30. In the crystal, the cations and anions, stacked one above the other along the c-axis direction, are held in place principally by electrostatic interactions. There are also C—H...Cl and C—H...O interactions, but these are rather weak. Of the six crystal structures reported to date for ionic salts of [Fe(DMF)6] n+ cations (n = 2, 3), five contain FeII ions. The title compound is the second example of a stable compound containing the [Fe(DMF)6] 3+ cation. The existence of both [Fe(DMF)6] 2+ and [Fe(DMF)6] 3+ cations shows that the DMF ligand coordination sphere can accommodate changes in the charge and spin states of the metal centre. [ABSTRACT FROM AUTHOR]

A convenient modification to the established synthetic routes for the preparation of complexes [M(CRCR)(dppe)Cp'] (M = Fe, Ru; Cp' = η5-C5H5 (Cp), η5-C5Me5 (Cp*); R = C6H5, C6H4-p-OMe, C6H4-p-NO2, tBu) and [Ru(CRCR)(PPh3)2Cp] from the corresponding [MCl(PP)Cp0] complex and the alkyne HCRCR via an intermediate vinylidene is described. The complexes are generally obtained as high quality crystalline samples directly from the reaction mixture. In agreement with previous studies, the iron complexes undergo a predominantly metal-centred oxidation, whilst there is greater involvement of the acetylide ligand in the oxidation processes associated with the ruthenium analogues. Analysis of the redox properties and spectroelectrochemical investigations reveal limited differences in the gross electronic structures of the Cp vs. Cp* derivatives in each of the Fe and Ru series. [ABSTRACT FROM AUTHOR]

Driven by an interest in the impact of the para-substituent of calix[4]arenes on metal complexation and structural chemistry, studies of p-cyclohexylcalix[4]arene (L) have been carried out. The 1:1 dichloromethane and dimethylformamide solvates were found to be isostructural, and different to the typical bilayer structure often observed for p-t-butylcalix[4]arene solvates. The methanol solvate, in contrast, does form a bilayered structure but is also a 1:1 solvate, unlike the p-t-butylcalix[4]arene·2MeOH system. Lanthanoid complexation was investigated, resulting in the structural characterisation of two different DMF solvates of a 2:2 dimeric europium complex, Eu2(L–3H)2(DMF)4. A tetrazole derivative, 5,11,17,23-tetracyclohexyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene, has been synthesised via the intermediate 5,11,17,23-tetracyclohexyl-25,27-dihydroxy-26,28-dicyanomethoxycalix[4]arene, with the latter compound being structurally characterised. Attempts to isolate lanthanoid clusters supported by the tetrazole derivative under conditions known to form Ln19 clusters with the p-t-butyl analogue were unsuccessful, resulting only in isolation of the ligand from the reaction mixture. [ABSTRACT FROM AUTHOR]

Three new NiII/ZnII heterometallics, [NiZnL′2(OMe)Cl]2 (1), [NiZnL′′(Dea)Cl]2·2DMF (2) and [Ni2(H3L′′′)2(o-Van)(MeOH)2]Cl·[ZnCl2(H4L′′′)(MeOH)]·2MeOH (3), containing three-dentate Schiff bases as well as methanol or diethanolamine (H2Dea) or o-vanillin (o-VanH), all deprotonated, as bridging ligands were synthesized and structurally characterized. The Schiff base ligands were produced in situ from o-VanH and CH3NH2 (HL′), or NH2OH (HL"), or 2-amino-2-hydroxymethyl-propane-1,3-diol (H4L′′′); a zerovalent metal (Ni and Zn in 1, Zn only in 2 and 3) was employed as a source of metal ions. The first two complexes are dimers with a Ni2Zn2O6 central core, while the third compound is a novel heterometallic cocrystal salt solvate built of a neutral zwitterionic ZnII Schiff base complex and of ionic salt containing dinuclear NiII complex cations. The crystal structures contain either centrosymmetric (1 and 2) or non-symmetric di-nickel fragment (3) with Ni⋯Ni distances in the range 3.146–3.33 Å. The exchange coupling is antiferromagnetic for 1, J = 7.7 cm−1, and ferromagnetic for 2, J = −6.5 cm−1 (using the exchange Hamiltonian in a form Ĥ = J12). The exchange interactions in 1 and 2 are comparable to the zero-field splitting (ZFS). High-field EPR revealed moderate magnetic anisotropy of opposite signs: D = 2.27 cm−1, E = 0.243 cm−1 (1) and D = −4.491 cm−1, E = −0.684 cm−1 (2). Compound 3 stands alone with very weak ferromagnetism (J = −0.6 cm−1) and much stronger magnetic anisotropy with D = −11.398 cm−1 and E = −1.151 cm−1. Attempts to calculate theoretically the exchange coupling (using the DFT "broken symmetry" method) and ZFS parameters (with the ab initio CASSCF method) were successful in predicting the trends of J and D among the three complexes, while the quantitative results were less good for 1 and 3. [ABSTRACT FROM AUTHOR]

The title compound undergoes two order–disorder transitions between 15 and 299 K, dictated by ordering of the guest molecules in the host cages, and resulting in three related crystal structures. We anticipate behaviour of this kind to be widespread, and speculate that the concept of “the crystal structure” for individual Dianin's clathrates may be elusive. [ABSTRACT FROM AUTHOR]

The title compound, [Co(C7H3N2O6)2(C2H6OS)2(H2O)2], has been prepared and its structure established by an X-ray structure determination in order to assist the modelling of processes of chemisorption of organic salts formed by di­nitro­benzoic acids (DNBH) and secondary amines ( R2NH) by metal surfaces. The 2,4-DNB ions and di­methyl sulfoxide (DMSO) mol­ecules behave as monodentate ligands coord­inated to the Co atom through their O atoms. These ligands, together with two mol­ecules of water, form a slightly distorted octahedral coordination environment for the Co atom which is disposed at a centre of symmetry. [ABSTRACT FROM AUTHOR]

Reactions of [Ru{C=C(H)‐1,4‐C6H4C≡CH}(PPh3)2Cp]BF4 ([1 a]BF4) with hydrohalic acids, HX, results in the formation of [Ru{C≡C‐1,4‐C6H4‐C(X)=CH2}(PPh3)2Cp] [X=Cl (2 a‐Cl), Br (2 a‐Br)], arising from facile Markovnikov addition of halide anions to the putative quinoidal cumulene cation [Ru(=C=C=C6H4=C=CH2)(PPh3)2Cp]+. Similarly, [M{C=C(H)‐1,4‐C6H4‐C≡CH}(LL)Cp ]BF4 [M(LL)Cp'=Ru(PPh3)2Cp ([1 a]BF4); Ru(dppe)Cp* ([1 b]BF4); Fe(dppe)Cp ([1 c]BF4); Fe(dppe)Cp* ([1 d]BF4)] react with H+/H2O to give the acyl‐functionalised phenylacetylide complexes [M{C≡C‐1,4‐C6H4‐C(=O)CH3}(LL)Cp'] (3 a–d) after workup. The Markovnikov addition of the nucleophile to the remote alkyne in the cations [1 a–d]+ is difficult to rationalise from the vinylidene form of the precursor and is much more satisfactorily explained from initial isomerisation to the quinoidal cumulene complexes [M(=C=C=C6H4=C=CH2)(LL)Cp']+ prior to attack at the more exposed, remote quaternary carbon. Thus, whilst representative acetylide complexes [Ru(C≡C‐1,4‐C6H4‐C≡CH)(PPh3)2Cp] (4 a) and [Ru(C≡C‐1,4‐C6H4‐C≡CH)(dppe)Cp*] (4 b) reacted with the relatively small electrophiles [CN]+ and [C7H7]+ at the β‐carbon to give the expected vinylidene complexes, the bulky trityl ([CPh3]+) electrophile reacted with [M(C≡C‐1,4‐C6H4‐C≡CH)(LL)Cp'] [M(LL)Cp'=Ru(PPh3)2Cp (4 a); Ru(dppe)Cp* (4 b); Fe(dppe)Cp (4 c); Fe(dppe)Cp* (4 d)] at the more exposed remote end of the carbon‐rich ligand to give the putative quinoidal cumulene complexes [M{C=C=C6H4=C=C(H)CPh3}(LL)Cp']+, which were isolated as the water adducts [M{C≡C‐1,4‐C6H4‐C(=O)CH2CPh3}(LL)Cp'] (6 a–d). Evincing the scope of the formation of such extended cumulenes from ethynyl‐substituted arylvinylene precursors, the rather reactive half‐sandwich (5‐ethynyl‐2‐thienyl)vinylidene complexes [M{C=C(H)‐2,5‐cC4H2S‐C≡CH}(LL)Cp']BF4 ([7 a–d]BF4 add water readily to give [M{C≡C‐2,5‐cC4H2S‐C(=O)CH3}(LL)Cp'] (8 a–d)]. [ABSTRACT FROM AUTHOR]

Reactions of the lanthanide(iii) picrates (picrate = 2,4,6-trinitrophenoxide = pic) with 1,10-phenanthroline (phen) and 2,2′:6′,2′′-terpyridine (terpy) in a 1 : 2 molar ratio have provided crystals suitable for X-ray structure determinations in instances predominantly involving the lighter lanthanides. In all, the aza-aromatic ligands chelate the lanthanide ion, none being found as 'free' ligands within the lattice. The complexes of 1,10-phenanthroline have been characterised in two forms, one unsolvated (Ln = La, Sm, Eu; monoclinic, C 2/ c , Z 8), one an acetonitrile monosolvate (Ln = Gd; monoclinic, P 21/ a , Z 4), the latter being the only previously known form (with Ln = La). In both forms, the LnIII is nine-coordinate, in an approximately tricapped trigonal-prismatic environment, with two picrate ligands chelating through phenoxide and 2-nitro group oxygen atoms, the third being bound through phenoxide-O only. The 2,2′:6′,2′′-terpyridine complexes, all acetonitrile monosolvates defined for Ln = La, Gd, Er, and Y (monoclinic, C 2/ c , Z 4), are ionic, one picrate having been displaced from the primary coordination sphere. For Ln = La, the two bound picrates are again chelating, making the LaIII 10-coordinate in a distorted bicapped square-antiprismatic environment but in the other species they are bound through phenoxide-O only, making the LnIII ions eight-coordinate in a distorted square-antiprismatic environment. Stacked arrays of the ligands can be found in both series of complexes, with intramolecular picrate–picrate and picrate–aza-aromatic stacks being prominent features. Structure determinations on complexes of lanthanide(III) picrates with aza-aromatic ligands provide examples of various stacking arrays. The chain of [La(terpy)2(pic)2]+ cations (shown in space-filling mode) present in the lattice of [La(terpy)2(pic)2](pic)·CH3CN involves both intra- and intermolecular heterogeneous stacks. [ABSTRACT FROM AUTHOR]

Single crystal X-ray structure determinations have been executed for several title compounds of the mononuclear form [LMX2], namely [(bpy)ZnX2], X = Cl, Br; [(phen)ZnX2], X = Cl, Br, I (bpy = 2,2′-bipyridine; phen = 1,10-phenanthroline). Also reported are the crystal structures of ZnSO4/bpy/H2O (1 : 1 : 5) (≡ [(bpy)Zn(OH2)4](SO4)·H2O) and Zn(NO3)2/bpy/H2O (1 : 1 : 3) (≡ [(bpy)Zn(OH2)3(O NO2)](NO3)). The sulfate complex completes the array [LM(OH2)4]2+, L = bpy, phen, M = Zn, Cd, while the nitrate is the first nitrate example for [LM(OH2)3(O X)](+) (O X = O NO2, O SO3). In all examples of the sulfate and nitrate forms here and previously defined, the metal atoms are six-coordinate, with any anionic donors lying in axial coordination sites (i.e. M–O (quasi-) normal to the LM plane). The structures of [LHg(SCN)2] (L = phen, tpy) (tpy = 2,2′:6′,2′-terpyridine), [(tpy)(CdBr2], and [Zn(tpy)2](NO3)2·2H2O are also recorded. Single crystal X-ray structure determinations have been executed for several mononuclear Zn halide, sulphate, and nitrate complexes with 2,2′-bipyridyl and 1,10-phenanthroline ligands. [ABSTRACT FROM AUTHOR]