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. Luminescence studies revealed excellent properties for their use in cell imaging with visible excitation and broad emission profiles. Their uptake in two distinct species has been examined by fluorescence imaging of the diplomonad fish parasite Spironucleus vortens (S. vortens) and rod-shaped yeast Schizosaccharomyces pombe (Schiz. pombe) as a function of their lipophilicity. The uptake of the complexes was highest for the more lipophilic 2+-5+ in both S. vortens and Schiz. pombe in which the long alkyl chain aids in crossing bilipid membranes. However, the increased lipophilicity of longer chains also resulted in greater toxicity. Localisation over the whole cell varied with differing alkyl chain lengths with complex 2+ preferentially locating to the nucleus of S. vortens, 3+ showing enhanced nuclear partitioning in Schiz. pombe, and 4+ for the remaining cell wall bound in the case of S. vortens. Interestingly, complexes of intermediate lipophilicity such as 7+ and 8+ showed reasonable uptake, proved to be non-toxic, and were capable of crossing exterior cell walls and localising in the organelles of the cells.

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. In solution, the Ag(I) and Au(I) complexes show a barrier to rotation about the Ctriazine-Namine bonds, with calculated ΔG(≠) barriers in the region of 70 kJ mol(-1). Single crystal X-ray structures of several of the proligands and their corresponding Ag(I) and Au(I) complexes were obtained. These universally reveal an extended, rigidly planar π-conjugated network between the triazine core, imidazolium/imidazolylidene substituents and exocyclic amine functions, to which the origin of the rotational barrier observed in solution is attributed. Only very weak Ntriazine-metal interactions are observed in the solid state, as indicated by small deviations of the CNHC-Ag-Cl bond angles from 180° and also supported by DFT calculations on the Ag(NHC)Cl complex (NHC = 4,6-dipiperidinyl-2-methylimidazolylidene triazine). Preliminary antimicrobial susceptibility studies against five microorganisms (methicillin resistant Staphylococcus aureus NCTC 13277, S. aureus NCTC 6571, Pseudomonas aeruginosa NCTC 10662, Proteus mirabilis NCTC 11938 and Candida albicans ATCC 90028) show that the above triazine-based Ag-NHC complexes are active antimicrobial and antifungal agents.

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. The bis-imidazolium salt 4I and platinum complexes cis-[Pt(2)(µ-2)(dmso)(2)Cl(4)] and cis-[Pt(2)(µ-4)(dmso)(2)Cl(4)] were characterised by X-ray crystallography. In the case of the Pt(II) complexes, the carbene ring is positioned in a sterically preferred orientation, approximately perpendicular to the platinum coordination plane. The (1)H, (13)C, (15)N and (195)Pt NMR spectra of the platinum complexes show the presence of rotamers due to hindered rotation about the carbene-metal bond.

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. Single-crystal X-ray analyses have been obtained for the majority of the complexes and NHC salts. The activity of these complexes was tested in the hydrogenation of a range of substrates with molecular hydrogen, including 1-cyclooctadiene and 2-methyl styrene, where they show enhanced activity and stability in comparison to non-functionalised NHC analogues, operating under exceptionally mild conditions (ambient temperature and atmospheric pressure).

Synthesis and characterisation of benzyl phosphino-thioether and -thiolato Pd(II) complexes and their applications in Suzuki coupling reactions.

The synthesis of the benzyl phosphinothioether derivatives Ph(2)PCH(2)CH(Et)SR and their corresponding palladium complexes are reported, where R = CH(2)Ph, R = CH(2)-3,5-Me-C(6)H(3) and R = 1-CH(2)C(10)H(7)(5). Crystallographic data obtained for the complexes Pd(3)Cl(2) and Pd(4)Cl(2) show intra- and inter-molecular pi-pi interactions between the aromatic rings on the P and S substituents, and NOE experiments for Pd(4)Cl(2) show that these interactions persist in solution. The performance of the phosphinothioether palladium complexes in aryl-aryl cross-coupling reactions is compared with that of the corresponding complex of the parent phosphinothiolato ligand Ph(2)PCH(2)CH(Et)S(-)(1). High turnover numbers up to 2000000 are reported for the coupling of bromobenzene, using the palladium dimer [Pd(1)I](2) as the catalyst precursor. Kinetic studies show a linear dependence of the reaction on catalyst loading. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported.