Mapping of N-C Bond Formation from a Series of Crystalline Peri-Substituted Naphthalenes by Charge Density and Solid-State NMR Methodologies.

A combination of charge density studies and solid state nuclear magnetic resonance (NMR) J coupling measurements supported by periodic density functional theory (DFT) calculations is used to characterise the transition from an n-π* interaction to bond formation between a nucleophilic nitrogen atom and an electrophilic sp carbon atom in a series of crystalline peri-substituted naphthalenes. As the N⋅⋅⋅C distance reduces there is a sharp decrease in the Laplacian derived from increasing charge density between the two groups at ca. N⋅⋅⋅C = 1.

[CrNi] Heterometallic Coordination Cubes.

Three new heterometallic [CrNi] coordination cubes of formulae [CrNiL(HO)](NO) (), [CrNiL(MeCN)(HO)](ClO) (), and [CrNiLCl] () (where HL = 1-(4-pyridyl)butane-1,3-dione), were synthesised using the paramagnetic metalloligand [CrL] and the corresponding Ni salt. The magnetic skeleton of each capsule describes a face-centred cube in which the eight Cr and six Ni ions occupy the eight vertices and six faces of the structure, respectively. Direct current magnetic susceptibility measurements on () reveal weak ferromagnetic interactions between the Cr and Ni ions, with = + 0.

All about that base: investigating the role of ligand basicity in pyridyl complexes derived from a copper-Schiff base coordination polymer.

The role of ligand basicity in complex formation has been investigated using monodentate pyridyls or benzimidazole (mP) in combination with a solution-stable species derived form a coordination polymer, [Cu(L)] (where L = 2-(2-hydroxybenzylidene-amino)phenol). The 12 [Cu(L)(mP)n] complexes generated, combined with the {[Cu(L)]2(pP)} complexes from our previous work (where pP is a polypyridyl ligand), allow us to gauge the likelihood of complex formation based on the pKa of the conjugate acid of the pyridyl ligands and Hammett parameter, σ. Above pKa ≈ 4.

Mono- and ditopic hydroxamate ligands towards discrete and extended network architectures.

A family of mono- and ditopic hydroxamic acids has been employed in the synthesis and structural and physical characterisation of discrete (0D) and (1- and 2-D) extended network coordination complexes. Examples of the latter include the 1-D coordination polymer {[Zn(ii)(LH)]·2MeOH} (5; LH = 2-(methylamino)phenylhydroxamic acid) and the 2-D extended network {[Cu(ii)(LH)(HO)(NO)]·HO} (5; LH = 4-amino-2-(acetoxy)phenylhydroxamic acid). The 12-MC-4 metallacrown [Cu(ii)(LH)(MeOH)(NO)]·3HO·4MeOH (7) represents the first metal complex constructed using the novel ligand N-hydroxy-2-[(2-hydroxy-3-methoxybenzyl)amino]benzamide (LH).

Crowding out: ligand modifications and their structure directing effects on brucite-like {M(μ-OH)} (M = Co(ii), Ni(ii)) core growth within polymetallic cages.

Previous employment of the ligands 2-methoxy-6-[(methylimino)methyl]phenol (LH) and 2-methoxy-6-[(phenylimino)methyl]phenol (LH) has resulted in the self-assembly of pseudo metallocalix[6]arene complexes of general formulae: [M(μ-OH)(L)](NO) (M = Ni(ii), x = 1, y = 2 (1) and Co(ii/iii), x = 2, y = 3 (2)). Extrapolating upon this work, we report the coordination chemistry of ligands 2-methoxy-6-{[(2-methoxyphenyl)imino]methyl}phenol (LH), 2-[(benzylimino)methyl]-6-methoxyphenol (LH), 2-[(benzylamino)methyl]-6-methoxyphenol (LH) and 2-[(benzylamino)methyl]-4-bromo-6-methoxyphenol (LH), whose structures are modifications of ligands LH. These ligands are employed in the synthesis and characterisation of the dimetallic complex [Ni(ii)(L)(HO)](NO)·2HO·3MeOH (3); the monometallic complexes [Ni(ii)(L)] (4) and [Co(iii)(L)]·HO·MeOH (5a); and the tetranuclear pseudo metallocalix[4]arene complexes: [(NO)⊂Co(ii)(μ-OH)(L)(HO)](NO)·HO (6), [(NO)⊂Ni(ii)(μ-OH)(L)(HO)](NO)·HO (7) and [Ni(ii)(μ-OH)(L)(NO)]·MeCN (8).

The Rich Solid-State Phase Behavior of dl-Aminoheptanoic Acid: Five Polymorphic Forms and Their Phase Transitions.

The rich landscape of enantiotropically related polymorphic forms and their solid-state phase transitions of dl-2-aminoheptanoic acid (dl-AHE) has been explored using a range of complementary characterization techniques, and is largely exemplary of the polymorphic behavior of linear aliphatic amino acids. As many as five new polymorphic forms were found, connected by four fully reversible solid-state phase transitions. Two low temperature forms were refined in a high ' crystal structure, which is a new phenomenon for linear aliphatic amino acids.

Exploring the cellular uptake and localisation of phosphorescent rhenium fac-tricarbonyl metallosurfactants as a function of lipophilicity.

A systematic study of the cellular uptake of emissive complexes as a function of their lipophilicity is presented. Here a series of amphiphilic rhenium fac-tricarbonyl bisimine complexes bearing axial substituted imidazole or thiazole ligands, [Re(bpy)(CO)3(ImCnHm)]+ {n = 1 m = 3 (1+), n = 4 m = 9 (2+), n = 8 m = 17 (3+), n = 12 m = 25 (4+), n = 16 m = 33 (5+), n = 2 m = 3 (6+); bpy = 2,2'-bipyridine, Im = imidazole} and [Re(bpy)(CO)3(L)]+ {L = 1-mesitylimidazole, ImMes (7+), 4,5-dimethylthiazole, dmt (8+) and 4-methyl-5-thiazole-ethanol, mte (9+)} is reported. The X-ray crystal structures of 2+, 8+ and 9+ confirm the geometry and expected distribution of ligands and indicated that the plane of the imidazole/thiazole ring is approximately parallel to the long axis of the bipy ligand.

Modular [FeM] (M = Pd, Co, Ni, Cu) Coordination Cages.

The reaction of the simple metalloligand [FeL] [HL = 1-(4-pyridyl)butane-1,3-dione] with a variety of different M salts results in the formation of a family of heterometallic cages of formulae [FePdL]Cl (1), [FeCuL(HO)Br]Br (2), [FeCuL(HO)](NO) (3), [FeNiL(SCN)Cl] (4), and [FeCoL(SCN)(HO)]Cl (5). The metallic skeleton of each cage describes a cube in which the Fe ions occupy the eight vertices and the M ions lie at the center of the six faces. Direct-current magnetic susceptibility and magnetization measurements on 3-5 reveal the presence of weak antiferromagnetic exchange between the metal ions in all three cases.

Biological and structural studies of phosphonium 'masked thiolate' compounds.

The ability of phosphonium cations to act as intracellular transport vectors is well-established. Phosphonioalkylthiosulfate zwitterions, and ω-thioacetylalkylphosphonium salts, which act as 'masked thiolate' ligands, are useful precursors for the formation of phosphonium-functionalised gold nanoparticles, enabling the nanoparticles to be transported into cells for diagnostic and therapeutic purposes. In this study we have completed cytotoxicity studies of ω-thioacetylpropylphosphonium salts derived from triphenylphosphine and tri(4-fluorophenyl)phosphine, which show that the compounds are only toxic towards PC3 prostate cancer cells at high concentrations and at prolonged incubation periods and display IC values of 67 μM and 252 μM respectively, significantly higher than those of other phosphonium salts.

Efficient Ni(II)2Ln(III)2 Electrocyclization Catalysts for the Synthesis of trans-4,5-Diaminocyclopent-2-enones from 2-Furaldehyde and Primary or Secondary Amines.

A series of heterometallic coordination clusters (CCs) [Ni(II)2Ln(III)2(L1)4Cl2(CH3CN)2] 2CH3CN [Ln = Y (1Y), Sm (1Sm), Eu (1Eu), Gd (1Gd), or Tb (1Tb)] were synthesized by the reaction of (E)-2-(2-hydroxy-3-methoxybenzylidene-amino)phenol) (H2L1) with NiCl2·6(H2O) and LnCl3·x(H2O) in the presence of Et3N at room temperature. These air-stable CCs can be obtained in very high yields from commercially available materials and are efficient catalysts for the room-temperature domino ring-opening electrocyclization synthesis of trans-4,5-diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere. Structural modification of the catalyst to achieve immobilization or photosensitivity is possible without deterioration in catalytic activity.

Synthesis and Evaluation of a 2,11-Cembranoid-Inspired Library.

The 2,11-cembranoid family of natural products has been used as inspiration for the synthesis of a structurally simplified, functionally diverse library of octahydroisobenzofuran-based compounds designed to augment a typical medicinal chemistry library screen. Ring-closing metathesis, lactonisation and SmI2 -mediated methods were exemplified and applied to the installation of a third ring to mimic the nine-membered ring of the 2,11-cembranoids. The library was assessed for aqueous solubility and permeability, with a chemical-space analysis performed for comparison to the family of cembranoid natural products and a sample set of a screening library.

Copper Keplerates: High-Symmetry Magnetic Molecules.

Keplerates are molecules that contain metal polyhedra that describe both Platonic and Archimedean solids; new copper keplerates are reported, with physical studies indicating that even where very high molecular symmetry is found, the low-temperature physics does not necessarily reflect this symmetry.

Switching the orientation of Jahn-Teller axes in oxime-based Mn(III) dimers and its effect upon magnetic exchange: a combined experimental and theoretical study.

A family of Mn(III) dimers of general formula [Mn(R-sao)2(dpa)2](ClO4)2 (1-5) has been synthesised using derivatised phenolic oximes (R-saoH2, where R = H, Me, Et, Ph) in combination with di-(2-picolyl)-amine (dpa). Their structures reveal a double-oxime bridged [Mn(III)(NO)]2 magnetic core in which the Jahn-Teller axes lie perpendicular to the bridging plane, in contrast to two previously reported family members (6, 7). The switch in the orientation of the Jahn-Teller axes is enforced through the use of the chelating ligand which is present in 1-5 and absent in 6-7.

Molecular Pac-Man and Tacos: layered Cu(II) cages from ligands with high binding site concentrations.

The in situ formation and subsequent Cu(ii) ligation of the polydentate pro-ligands o-[(E)-(2-hydroxy-3-methoxyphenyl)methylideneamino]benzohydroxamic acid (L1H3), o-[(E)-(2-hydroxy-3-methoxy-5-bromophenyl)methylideneamino]benzohydroxamic acid (L2H3) and o-[(E)-(2-hydroxyphenyl)methylideneamino]benzohydroxamic acid (L3H3), leads to the self-assembly of the cages [Cu(ii)10(L1)4(2-aph)2(H2O)2](ClO4)4·5MeOH (), [Cu(ii)14(L1)8(MeOH)2.5(H2O)7.5](NO3)4·3MeOH·7H2O (), [Cu(ii)14(L2)8(MeOH)4(H2O)6](NO3)4·6H2O (), [Cu(ii)14(L3)8(MeOH)6(H2O)2](NO3)4·4MeOH·8H2O () and [Cu(ii)30O(OH)4(OMe)2(L1)16(MeOH)4(H2O)2](ClO4)4·2MeOH·30H2O ().

Synergistic catalysis: enantioselective addition of alkylbenzoxazoles to enals.

A novel catalytic enantioselective methodology based on synergistic catalysis is reported. The strategy involves: 1) the metal-Lewis-acid activation of alkylazaarenes, and 2) the secondary-amine activation of enals. Consequently, highly functionalized chiral alkylazaarenes were obtained in good yields and with reasonable stereoselectivity.

Synergistic catalysis: highly diastereoselective benzoxazole addition to Morita-Baylis-Hillman carbonates.

An expedited method has been developed for the diastereoselective synthesis of highly functionalized alkyl-azaarene systems with good yields and high diastereoselectivities (>15 : 1 dr). The methodology includes a synergistic catalysis event involving organometallic (10 mol% AgOAc) activation of an alkyl azaarene and Lewis base (10 mol% DABCO) activation of a Morita-Baylis-Hillman carbonate. The structure and relative configuration of a representative product were confirmed by X-ray analysis.

Systematic experimental charge density analysis of anion receptor complexes.

The first systematic electronic resolution study of a series of urea-based anion receptor complexes is presented. The hydrogen bonding in these multi-component systems was fully characterised using Bader's Quantum Theory of Atoms In Molecules (QTAIM) with the strength of the various N-H···anion hydrogen bonds quantified and the individual contributions of different intermolecular forces to the overall receptor: anion interaction derived by comparison of the charge densities in the related complexes. The strength of the N-Hanion hydrogen bonds was correlated to the basicity of the anion and related to the structure of the receptors.

CO2 as a reaction ingredient for the construction of metal cages: a carbonate-panelled [Gd6Cu3] tridiminished icosahedron.

A CO3(2-)-panelled [Gd(III)6Cu(II)3] cage conforming to a tridiminished icosahedron is synthesised by bubbling CO2 through a solution of Gd(III) and Cu(II) ions.

"Converting" an hexametallic MnIII wheel to a dodecametallic MnIII wheel via ligand oximation.

Ligand oximation "converts" an hexametallic Mn(III) wheel into a dodecametallic Mn(III) wheel, while the magnetic exchange switches from ferro- to antiferromagnetic.

Combining oxime-based [Mn6] clusters with cyanometalates: 1D chains of [Mn6] SMMs from [M(CN)2]- (M = Au, Ag).

The linear [M(CN)2](-) (M = Au, Ag) anions can be used as metalloligands in oxime-based Mn chemistry to afford 1D chains of [Mn(III)6] single-molecule magnets (SMMs).

Synthesis of fumaramide derived [3]rotaxanes as potential precursors for molecular boxes.

Three new fumaramide-derived [3]rotaxanes have been synthesized, with the aim of macrocycle linking to form a molecular box. In one case, a nine-component templated [3]rotaxane synthesis was accomplished in 40% yield. Rotaxane reduction resulted in an unexpectedly facile de-slipping process.

Luminescent, enantiopure, phenylatopyridine iridium-based coordination capsules.

The first molecular capsule based on an [Ir(ppy)(2)](+) unit (ppy = 2-phenylatopyridine) has been prepared. Following the development of a method to resolve rac-[(Ir(ppy)(2)Cl)(2)] into its enantiopure forms, homochiral Ir(6)L(4) octahedra where obtained with the tritopic 1,3,5-tricyanobenzene. Solution studies and X-ray diffraction show that these capsules encapsulate four of the six associated counteranions and that these can be exchanged for other anionic guests.

Anion-induced shuttling of a naphthalimide triazolium rotaxane.

The anion-templated synthesis of a rotaxane structure, incorporating the new naphthalimide triazolium motif, is described and the interlocked host shown to exhibit selective, uni-directional, anion-induced shuttling. Initial pseudorotaxane investigations demonstrate the ability of a naphthalimide triazolium threading component to form interpenetrated assemblies with counter-anion-dependent co-conformations. (1)H NMR studies reveal that the shuttling behaviour of the analogous rotaxane host system is controlled by selective anion binding and by the nature of the solvent conditions.

Semipinacol rearrangement of cis-fused β-lactam diols into keto-bridged bicyclic lactams.

The 6-azabicyclo[3.2.1]octane ring system, prevalent in a range of biologically active molecules, is prepared through a novel semipinacol rearrangement utilizing a cyclic phosphorane or sulfite intermediate.

Complexes of lanthanide nitrates with tri tert butylphosphine oxide.

Reaction of lanthanide nitrates with (t)Bu(3)PO (=L) lead to the isolation of complexes Ln(NO(3))(3)L(2)·H(2)O·nEtOH (Ln = La (1), Nd(2)), Ln(NO(3))(3)L(2) ·nEtOH (Sm(3), Eu(4)), and Ln(NO(3))(3)L(2) (Dy(5), Er(6), Lu(7)). These have been characterized by elemental analysis, infrared and NMR((1)H, (13)C and (31)P) spectroscopy and single-crystal X-ray diffraction. The structures show L to be positioned on opposite sides of the metal with the nitrates forming an equatorial band.