Alkyl chain functionalised Ir(iii) complexes: synthesis, properties and behaviour as emissive dopants in microemulsions.

Six iridium(iii) complexes of the general form [Ir(C^N)(N^N)]X (where C^N = cyclometalating ligand; N^N = disubstituted 2,2'-bipyridine), and incorporating alkyl chains of differing lengths (C8, C10, C12), have been synthesised and characterised. The complexes have been characterised using a variety of methods including spectroscopies (NMR, IR, UV-Vis, luminescence) and analytical techniques (high resolution mass spectrometry, cyclic voltammetry, X-ray diffraction). Two dodecyl-functionalised complexes were studied for their behaviour in aqueous solutions.

Synthesis, molecular docking and antibacterial activity of an oxadiazole-based lipoteichoic acid inhibitor and its metabolites.

Amongst drug resistant Gram-positive bacteria, is a pathogen of great concern as it is the leading cause of life-threatening nosocomial and community acquired infections which are often associated with implanted medical devices. The biosynthesis of lipotheicoic acid (LTA) by has been recognized as a promising antibacterial target, owing its critical role in the growth and survival of Gram-positive bacteria. Here we report for the first time the chemical synthesis and characterisation of an oxadiazole based compound (1771), previously described as an inhibitor of LTA biosynthesis by targeting Lta synthase enzyme (LtaS).

A Mechanochemical Zinc-Mediated Barbier-Type Allylation Reaction under Ball-Milling Conditions.

A ball-milling-enabled zinc-mediated Barbier-type allylation reaction is reported. Notably, running the reaction in this manner renders it effective irrespective of the initial morphology of the zinc metal. The process is operationally simple, does not require inert atmospheres or dry solvents, and is reported over a range of aldehyde and ketone substrates; a gram-scale process is demonstrated.

Towards dual SPECT/optical bioimaging with a mitochondrial targeting, Tc(i) radiolabelled 1,8-naphthalimide conjugate.

A series of six different 1,8-naphthalimide conjugated dipicolylamine ligands (L1-6) have been synthesised and characterised. The ligands possess a range of different linker units between the napthalimide fluorophore and dipcolylamine chelator which allow the overall lipophilicity to be tuned. A corresponding series of Re(i) complexes have been synthesised of the form fac-[Re(CO)3(L1-6)]BF4.

A Ball-Milling-Enabled Reformatsky Reaction.

An operationally simple one-jar one-step mechanochemical Reformatsky reaction using in situ generated organozinc intermediates under neat grinding conditions has been developed. Notable features of this reaction protocol are that it requires no solvent, no inert gases, and no pre-activation of the bulk zinc source. The developed process is demonstrated to have good substrate scope (39-82 % yield) and is effective irrespective of the initial morphology of the zinc source.

Structural evolution in metallomicroemulsions - the effect of increasing alcohol hydrophobicity.

Small-angle neutron scattering and contrast variation has been employed to quantify how a series of alcohols with increasing hydrophobicity exert different abilities to structure a model toluene based metallomicroemulsion - a microemulsion system stabilised with a metallosurfactant. Classical microemulsion phase evolution and droplet structure are observed, leading to an oil rich core stabilised by a surfactant film containing a highly concentrated, hydrated metal ion layer.

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.

Ligand-Tuneable, Red-Emitting Iridium(III) Complexes for Efficient Triplet-Triplet Annihilation Upconversion Performance.

A series of substituted 2-phenylquinoxaline ligands have been explored to finely tune the visible emission properties of a corresponding set of cationic, cyclometallated iridium(III) complexes. The electronic and redox properties of the complexes were investigated through experimental (including time-resolved luminescence and transient absorption spectroscopy) and theoretical methods. The complexes display absorption and phosphorescent emissions in the visible region that are attributed to metal to ligand charge-transfer transitions.

EPR/ENDOR and Computational Study of Outer Sphere Interactions in Copper Complexes of Phenolic Oximes.

Copper complexes of the phenolic oxime family of ligands (3-X-salicylaldoximes) are used extensively as metal solvent extractants. Incorporation of electronegative substituents in the 3-position, ortho to the phenol group, can be used to buttress the interligand H-bonding, leading to an enhancement in extractant strength. However, investigation of the relevant H-bonding in these complexes can be exceedingly difficult.

Cationic, luminescent cyclometalated iridium(III) complexes based on substituted 2-phenylthiazole ligands.

Ten cationic heteroleptic iridium(III) complexes, [Ir(emptz)2(N^N)](PF6) were prepared from a cyclometalated iridium bridged-chloride dimer involving two ethyl-4-methylphenylthiazole-5-carboxylate (emptz) ligands. One X-ray crystallographic study was undertaken where the ancillary N^N ligand was 4,7-diphenyl-1,10-phenanthroline and revealed the anticipated structure, showing a distorted octahedral coordination geometry at Ir(III). The complexes were visibly luminescent with modestly structured emission at 540-590 nm and lifetimes (60-340 ns) consistent with phosphorescence.

Convenient syntheses of cyanuric chloride-derived NHC ligands, their Ag(I) and Au(I) complexes and antimicrobial activity.

Convenient syntheses of mono- and bis-imidazolium 1,3,5-triazine derivatives bearing piperidine and morpholine substituents are reported. In situ deprotonation of the mono-imidazolium salts and reaction with Ag2O or Au(tht)Cl (tht = tetrahydrothiophene) precursors affords the corresponding Ag(NHC)Cl and Au(NHC)Cl carbene complexes. In the presence of Ag(I) or Au(I) salts the bis-imidazolium pincers eliminate the imidazolium group to afford -OMe or -NMe2 substituted triazines depending on the solvent used.

Chiral Ag(I) and Pt(II) complexes of ditopic NHC ligands: synthesis, structural and spectroscopic properties.

The butyl and isopropyl derivatives (4I, 5Br) of chiral pool derived bis-imidazolium dehydrohexitol salts have been prepared. The ditopic N-heterocyclic carbenes 4 and 5 form dinuclear Ag(I) and Pt(II) complexes. All compounds were fully characterised by multinuclear NMR spectroscopy.

Interactions of an asymmetric amine with a non-C2 symmetric Cu-salen complex: an EPR/ENDOR and HYSCORE investigation.

Single enantiomers of R-/S-methylbenzylamine (MBA) were found to selectively form adducts with the chiral non-C(2) symmetric Cu-salen complex N-(3,5-di-tert-butylsalicylidene)-N'-(salicylidene)-cyclohexane-1,2-diamine copper(II), hereafter labelled [Cu(3)]. The g/A spin Hamiltonian parameters of this Cu(II) complex showed a decrease in symmetry from axial to rhombic upon formation of the [Cu(3)] + MBA adducts. The selectivity in enantiomeric discrimination was found to be only 59 ± 5% in favour of the heterochiral R,R'-[Cu(3)] + S-MBA and S,S'-[Cu(3)] + R-MBA adducts.

Visualizing diastereomeric interactions of chiral amine-chiral copper salen adducts by EPR spectroscopy and DFT.

Single enantiomers of R/S-methylbenzylamine (MBA) were found to selectively form adducts with two chiral Cu-salen complexes, [Cu(II)(1)] (H(2)1 = N,N'-bis(3,5-ditert-butylsalicylidene)-1,2-diaminocyclohexane) and [Cu(II)(2)] (H(2)2 = N,N'-bis-salicylidene-1,2-cyclohexanediamino). The axial g/A spin Hamiltonian parameters of the Cu-MBA adducts were typical of 5-coordinate species. Enantiomer discrimination in the MBA binding was directly evidenced by W-band CW EPR, revealing an 86 ± 5% preference for formation of the R,R-[Cu(1)] + S-MBA adducts compared to R,R-[Cu(1)] + R-MBA; this was reduced to a 57 ± 5% preference for R,R-[Cu(2)] + S-MBA following removal of the tert-butyl groups.

Expanded ring and functionalised expanded ring N-heterocyclic carbenes as ligands in catalysis.

The synthesis of new functionalised 6- and 7-membered NHC (N-heterocyclic carbene) precursors bearing anisidyl or pyridine N-substituents, both symmetrically and non-symmetrically substituted is reported. Their corresponding rhodium(i) and iridium(i) complexes, M(COD)(NHC)Cl, were also prepared and characterised. The unusual Rh(iii)/Rh(i) salt, [Rh(eta(2)-NHC-py)(2)Cl(2)][Rh(COD)Cl(2)], was obtained with one of the pyridyl-functionalised NHC ligands.

Formation of a cobalt(III)-phenoxyl radical complex by acetic acid promoted aerobic oxidation of a Co(II)salen complex.

The activation of N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino Co(II), [Co(II)(1)], by the addition of acetic acid under aerobic conditions has been investigated by a range of spectroscopic techniques including continuous-wave EPR, HYSCORE, pulsed ENDOR, and resonance Raman. These measurements have revealed for the first time the formation of a coordinated cobalt(III)-bound phenoxyl radical labeled [Co(III)(1(*))(OAc)(n)](OAc)(m) (n = m = 1 or n = 2, m = 0). This cobalt(III)-bound phenoxyl radical is characterized by the following spin Hamiltonian parameters: g(x) = 2.

1,1'-(Ethane-1,2-di-yl)bis-(1,4,7-triazonane).

In the centrosymmetric title compound (dtne), C(14)H(32)N(6), two 1,4,7-triaza-cyclo-nonane (tacn, or 1,4,7-triazonane) moieties are linked together each at an amino position by a single ethyl-ene spacer. The mol-ecular packing is supported by pairs of inter-molecular N-H⋯N hydrogen bonds, which form R(2) (2)(22) ring motifs and link the mol-ecules into infinite chains running parallel to the a axis.

Facile syntheses of dissymmetric ferrocene-functionalized Lewis acids and acid-base pairs.

A facile synthetic approach is reported for the synthesis of dissymmetric 1,2-ferrocenediyl Lewis acids and mixed acid-base pairs including the first example of a 1-phosphino-2-borylferrocene; the use of non-racemic electrophiles allows for the isolation of single diastereomer products.

Evaluation of electronics, electrostatics and hydrogen bond cooperativity in the binding of cyanide and fluoride by Lewis acidic ferrocenylboranes.

Synthetic approaches based on the direct borylation of ferrocene by BBr(3), followed by boryl substituent modification, or on the lithiation of ferrocene derivatives and subsequent quenching with the electrophile FBMes(2), have given access to a range of ferrocene derivatized Lewis acids with which to conduct a systematic study of fluoride and cyanide binding. In particular, the effects of borane electrophilicity, net charge, and ancillary ligand electronics/cooperativity on the binding affinities for these anions have been probed by a combination of NMR, IR, mass spectrometric, electrochemical, crystallographic, and UV-vis titration measurements. In this respect, modifications made at the para position of the boron-bound aromatic substituents exert a relatively minor influence on the binding constants for both fluoride and cyanide, as do the electronic properties of peripheral substituents at the 1'- position (even for cationic groups).

Enantioselective binding of structural epoxide isomers by a chiral vanadyl salen complex: a pulsed EPR, cw-ENDOR and DFT investigation.

The mode of chiral interaction between a series of asymmetric epoxides (propylene oxide, butylene oxide, epifluorohydrin and epichlorohydrin) and a chiral vanadyl salen complex, N, N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino-vanadium (iv) oxide, [VO()], was investigated by a range of electron magnetic resonance techniques (EPR, ENDOR, HYSCORE) and DFT. Enantiomer discrimination of the weakly bound epoxides by the vanadyl complex was evident by cw-ENDOR. The origin of this discrimination was attributed to a number of factors including H-bonds, steric properties and electrostatic contributions, which collectively control the outcome of the chiral interaction.

Locus-specific microemulsion catalysts for sulfur mustard (HD) chemical warfare agent decontamination.

The rates of catalytic oxidative decontamination of the chemical warfare agent (CWA) sulfur mustard (HD, bis(2-chlororethyl) sulfide) and a range (chloroethyl) sulfide simulants of variable lipophilicity have been examined using a hydrogen peroxide-based microemulsion system. SANS (small-angle neutron scattering), SAXS (small-angle X-ray scattering), PGSE-NMR (pulsed-gradient spin-echo NMR), fluorescence quenching, and electrospray mass spectroscopy (ESI-MS) were implemented to examine the distribution of HD, its simulants, and their oxidation/hydrolysis products in a model oil-in-water microemulsion. These measurements not only present a means of interpreting decontamination rates but also a rationale for the design of oxidation catalysts for these toxic materials.

Aqueous solutions of transition metal containing micelles.

Incorporation of d- or f-block metals into ligand systems that renders a metal complex surface-active or drives its partitioning into surfactant phases enables the localisation of chemical functionality at interfaces. This article discusses a number of fundamental aspects of these interesting materials and examines potential applications.