Influence of Functionalized η6 -Arene Rings on Ruthenium(II) Curcuminoids Complexes

A series of organometallic Ru(II) complexes containing functionalized η6‐arene ligands, together with curcumin and bisdemethoxycurcumin as O,O’‐chelating ligands and their RAPTA (ruthenium arene complexes bearing the 1,3,5‐triaza‐7‐phosphaadamantane ligand) type ionic derivatives is reported. The complexes were characterized by elemental analysis, infrared, 1H and 13C NMR, ESI‐MS spectrometry, and by single‐crystal X‐ray structure analysis. The cytotoxic activity of the complexes has been evaluated against human ovarian A2780 and A2780cisR cancer cell lines as well as non‐tumorigenic human embryonic kidney HEK 293 cells.

Structure, dynamics and catalytic activity of ruthenium(II)-arene phosphine complexes

This thesis encompasses work on the coordination chemistry and catalytic activity of half sandwich ruthenium(II)-arene phosphine complexes. The investigation of phosphine dissociation and association reactions of these complexes represents the unifying theme of this study and, in addition to providing fundamental insights into the coordination chemistry of these compounds, allowed structure-activity relationships to be made and assisted in the development of new synthetic procedures. The thesis is organised into three parts according to the type of phosphine ligand investigated. The dissociation characteristics and catalytic activity of bis-phosphine complexes are presented in Chapter 2. The former properties were established by kinetic studies of ligand exchange and gasphase fragmentation analysis by tandem mass spectrometry, and helped to rationalise trends in the observed catalytic activity for the hydrogenation of styrene to ethylbenzene. The more active complexes were also shown to be chemoselective catalysts for the hydrogenation of aldehydes in the presence of olefinic bonds. Mechanistic studies were carried out in order to rationalise the preferential hydrogenation of aldehydes, which is consequently suggested to proceed via an ionic outer-sphere mechanism. Chapter 3 describes investigations on the coordination chemistry of ruthenium(II)-arene complexes containing diphosphine ligands. Complexes containing κ1-coordinated diphosphine ligands, with or without triphenylphosphine as a co-ligand, were prepared or characterised as the corresponding borane adducts. Mechanistic studies, including determination of enthalpies, entropies and, in two cases, volumes of activation, for the chelation reactions of the isolated κ1-diphosphine complexes were undertaken. The coordination chemistry of a chiral diphosphine, (R)-BINAPO, was also investigated; the synthesis of complexes containing this ligand in a range of coordination modes was achieved. The final chapter concerns the reactivity and catalytic activity of ruthenium(II) complexes containing (PPh2CH2)3CMe (triphos). Investigations of the catalytic activity of ruthenium(II)-arene complexes containing the κ2-coordinated triphos ligand were carried out together with pertinent reactivity studies and comparisons to structural analogues, which helped rationalise the observed activities. The reactivity and catalytic chemistry of one of the structural analogues, a ruthenium(II)-acetate κ3-triphos complex, was also investigated in detail as it proved to be a highly active catalyst for the hydrogenation of 1-alkenes.

EPFL2007

Interface Investigations on Titanium Nitride Bilayer Systems

Dominik Anwar Jaeger

Nanocomposite coatings composed of two phases with atomically sharp phase boundaries, show interesting mechanical properties. These properties are often originating from their high interface to volume ratio. Composites of nanocrystalline titanium nitride (TiN) grains surrounded by a one to two monolayer thick interlayer of silicon nitride (Si3N4) show an enhanced nanohardness. The central theme of this thesis is concernedwith the interfacial properties of two-dimensional bilayer systems, which are used as model systems to describe the interfaces occurring in nanocomposite coatings. The systems under investigation are TiN interfaces in contact with silicon (Si), silicon nitride (Si3N4) and aluminum nitride (AlN). The primary tool used to analyze the interfaces of bilayer systems is X-ray Photoelectron Spectroscopy (XPS) with emphasis put on the shake-up feature of the Ti 2p photoelectron line. Shake-ups in TiN are observed as an additional peak on the lower binding energy side of the energy lines of the Ti 2p orbitals. Shake-ups are strongly influenced by valence electrons and electron density distributions. This makes them a powerful tool to probe the chemical and electronic structure of TiN interfaces. The aim of this study is to utilize the shake-up energy and its intensity to gain insight into interfacial structures and correlate their changes to interfacial polarization and macroscopic mechanical properties. Single crystalline (sc-) and oxygen-free TiN as well as oxygen-free bilayer systems were deposited by unbalanced magnetron sputtering and analyzed by Angle Resolved (AR-)XPS. Bilayer samples were deposited and their quality was controlled using X-ray diffraction (crystallinity), Rutherford back scattering (elemental composition), and atomic force microscopy (roughness). All XPS samples were fabricated, transfered and analyzed whilst maintaining ultra high vacuum. A precise and self-consistent XPS data processing method was developed to evaluate Ti 2p spectra. This method accounts for the correct photoelectron line shape, background subtraction and photoelectron peak area intensity. Binding energy, shake-up energy and intensity ratios of shake-ups taken frompristine TiN surfaces are precisely determined, and the influence of oxygen on the information content in peak positions and intensities was investigated. The shake-up energy and intensity of bulk sc-TiN and its origin of the shake-up are discussed. An analytical description for the XPS signal ratio of bilayer systems is derived to separate the interfacial signals from the bulk information. The results obtained by this analytical description are strongly influenced by the interface thickness that has been found to be proportional to the overlayer thickness. The revealed interface properties show a correlation between the shake-up intensity and the interface morphology, oxygen content, overlayer material and overlayer thickness. AR-XPS and X-ray Photoelectron Diffraction (XPD) results were used to interpret the crystalline structure of the different TiN/AlN and TiN/Si3N4 bilayer systems. AlN shows XPD patterns indicating a crystalline growth of AlN on sc-TiN. The electrically insulating AlN overlayer creates a charge accumulation at the TiN interface, which results in an enhanced shake-up intensity. XPD patterns of Si3N4 systems revealed a crystalline growth of Si3N4 in the first 0.6nm. The intensity of the diffraction patterns reduces with increasing Si3N4 overlayer thickness due to a change in the growth behavior from crystalline to amorphous structures. Si3N4 films show, in comparison to AlN, reduced interface charging and hence a lower shakeup intensity. The crystalline growth of Si3N4 in the initial stages is hindered in systems where a bias voltage is applied to the substrate during the deposition process. In contrast to the unbiased systems, which have crystalline interfacial structures, the biased systems no longer show XPD patterns due to a loss of crystallinity. Additionally the shake-up intensity of biased systems is thickness-independent, which is in contrast to unbiased systems. The difference in the shake-up intensity of biased and unbiased Si3N4 is explained by a different band gap of the Si3N4 structure in the first two monolayers. This thesis shows that the increase in the shake-up intensity is correlated to intrinsic and extrinsic interface charging. The obtained results, in combination with theoretical structure models from literature, show that in one to two monolayer thick interlayers a build-up of interface polarization is unlikely. The observed nanohardness enhancement in TiN/Si3N4 systems is explained with already known hardness effects.

EPFL2012

Cytotoxicity of ruthenium-arene complexes containing B-ketoamine ligands

Catherine Marie Amélie Clavel, Paul Joseph Dyson, Rosario Scopelliti

New ruthenium(II) arene derivatives (arene = p-cymene, benzene, hexamethylbenzene) containing beta-ketoamine ligands L' (HL' in general; in detail, HLph,ph = (4Z)-3-methyl-4-((phenylamino)(phenyl)methylene)-1-phenyl-1H-pyrazol-5(4H)-one, HLnaph,ph = (4Z)-3-methyl-4-((phenyamino)(naphthalen-2-yl)methylene)-1-phenyl-1H-pyrazol-5(4H)- one, HLet,ph = (4Z)-3-methyl-4-(1-(phenylamino)propylidene)-1-phenyl-1Hpyrazol-5(4H)-one) have been synthesized and characterized by spectroscopy (IR, ESI-MS, H-1 and C-13 NMR) and elemental analysis. The ligands in the anionic form coordinate ruthenium in a chelating kappa N-2,O-bidentate fashion, affording 1:1 derivatives of the formula [Ru(arene)(L')Cl]. Further reaction of [Ru(p-cymene)(L')Cl] with AgPF6 or PTA (PTA = 1,3,5-triaza-7-phosphaadamantane) in methanol affords [Ru(p-cymene)(L')(CH3OH)] [PF6] and [Ru(p-cymene) (L')(PTA)]Cl, respectively. The solid-state structures of the ligand HLet,ph and complexes [Ru(p-cymene)(L-ph,L-ph)Cl] (1), [Ru(p-cymene)(L-naph,L-ph)Cl] (4), and [Ru(p-cymene)(L-et,L-ph)Cl] (7) have been determined by single-crystal X-ray diffraction. The antitumor activity of both the ligands and complexes has been evaluated against the human ovarian carcinoma cell line A2780 and its cisplatin-resistant equivalent A2780R, some of the complexes showing significant cytotoxicity toward the cisplatin-resistant cell line.

American Chemical Society2013

Interface Investigations on Titanium Nitride Bilayer Systems

Dominik Anwar Jaeger

EPFL2012

Structure, dynamics and catalytic activity of ruthenium(II)-arene phosphine complexes

EPFL2007