1981 Commencement Program

May commencement.https://digitalcommons.cortland.edu/commencements_programs/1134/thumbnail.jp

Structural and photophysical characterisation of coordination and optical isomers of mononuclear ruthenium(II) polypyridyl 1,2,4-triazole complexes

The X-ray crystal structure of the N2 isomers of the Ru(bipy)2 complexes of Hphpztr (1) and Hpztr (2), (bipy = 2,2'-bipyridine, Hphpztr = 2-(5'-phenyl-4'H-[1,2,4]triazol-3'-yl)pyrazine and Hpztr = 2-(4'H-[1,2,4]triazol-3'-yl)pyrazine) are reported. The molecular structure obtained for 2 demonstrates an interesting structural aspect in the sharing of a single proton between two molecular units. The isolation of the Δ and Λ stereoisomers of 1 and [Ru(phen)2(pztr)]+ (phen = 1,10-phenanthroline) (3) by semipreparative HPLC is also reported. The compounds obtained are characterised by electronic spectroscopy and particular attention is paid to the photophysical properties of Δ and Λ isomers of 1 and 3, in chiral enantiopure and racemic solvents

New Student Directory, The Class of 2006

Directory of newly admitted students and new faculty members. The student directory includes photographs of the 324 students and student information including name, high school attended, city and state, activities, and/or area of academic interest. The 48page directory is a simple, paper bound booklet featuring both a recent and older photo of Kauke Hall and the title, \u27The College of Wooster New Student Directory, Class of 2006\u27 on the cover.https://openworks.wooster.edu/directories/1053/thumbnail.jp

Synthesis of Novel Targeted Drug Delivery Systems for Cancer Therapy

One of the most important goals of pharmaceutical science is local izing the pharmacological activity of the drug at the site of action. Drug delivery systems - are. molecular tools which without undesired interaction at other sites target a specific drug receptor. In this work a· novel folate-cyclodextrin conjugate was synthesised for potential use as a drug delivery system in cancer therapy. Folate was directly covalently bound to an amino derivative of p-Cyclodextrin with a view to decreasing the polydispersity of the carrier system. Ultimately the cyclodextrin cavity will be used to transport drugs to the site of action. This study also describes the structural characterisation of the novel folatecyclodextrin conjugate using a range of techniques including electronic, vibrational, NMR, MALDI-MS and ESI-MS spectroscopies, all of which provided evidence that the folate moiety was bound to the cyclodextrin through an amide linkage. HPLC analysis was employed to study the purity of the conjugate prepared and provided evidence of the formation of a and y structural isomers. The photostability of the conjugate was assessed using electronic spectroscopy and the formation of particles was detected by light scattering. Preliminary biological evaluation of the tumour targeting device was carried out using HeLa cells and no evidences of cytotoxicity are recorded

Probing ground and excited state properties of ruthenium (II) and osmium (II) polypyridyl complexes

The area of ruthenium(H) and osmium(H) polypyridyl chemistry has been the subject of intense investigation over the last half century. In chapter 1, topics relevant to the studies presented in this thesis are introduced. These areas include the basic principles behind the ground and excited state properties of Ru(II) and Os(II) polypyridyl complexes, complexes incorporating the 1,2,4-triazole moiety and the application of deuteriation to inorganic photophysics. Chapter 2 details experimental and basic synthetic procedures employed in the studies presented in later chapters. A limited discussion of practical aspects of both synthetic procedures and physical measurements is included, in particular where major difficulties were encountered and where improvements to standard procedures were made. A central theme to this thesis is the application of deuteriation as a spectroscopic probe. In order to fully exploit its potential fully, a general and systematic approach to the deuteriation of polypyridyl type ligands is required. In chapter 3 a range of isotopomers of heteroaromatic compounds containing pyrazyl-, pyridyl-, 1,2,4-triazole-, thienyl-, methyl-, and phenyl- moieties, are reported. The application of deuteriation in inorganic chemistry as a spectroscopic probe both in simplification of NMR and Raman spectra and as a probe into the excited state structure of heteroleptic complexes is the focus of chapter 4. Deuteriation is employed extensively to probe the excited state structure of several series of Ru(II) and Os(II) polypyridyl complexes. In particular the effect of deuteriation on emission lifetime and ground and excited state resonance Raman spectra is investigated. In chapter 5, the phenomena of temperature dependent dual luminescence observed for the mononuclear complex [Ru(bpy)2 (pztr)]+ forms the basis of a wider investigation of related complexes in an effort to gain more insight into the nature of the phenomenon. In addition some fundamental studies into the picosecond excited state processes of [Ru(bpy)3]2+ are presented. In these studies deuteriation shows itself as a powerful tool in effecting small but important perturbations. In Chapter 6 the separation, characterisation and photophysical properties of the stereoisomers of mono- and bi-nuclear Ru(II) polypyridyl complexes is examined. In particular the importance of chirality both in terms of solvent and in complex in determining the circular dichroism, ]H NMR spectroscopy and photophysical properties is investigated. In chapters 7 and 8, attention is turned to binuclear systems incorporating 1,2,4-triazole moieties. The effects of variations in the bridging ligand in these systems (e.g., distance and spacer groups, pyrazine vs. triazole etc.) are examined. Deuteriation is employed in some of these systems as a tool in assessing the localisation of the lowest emissive excited state on particular moieties of the complexes

Ru(II) polypridyl complexes investigated from the pico to the micro second domain

The present work probes the ground and excited state energy structures of a variety of Ru(II) complexes to better understanding the factors which affect their photo - chemical and - physical properties. In the picosecond domain, ultrafast time resolved resonance Raman spectroscopy has been used to investigate the rate of formation of the thermally equilibrated excited (THEXI) state in [Ru(bpy)3]2+. These studies have shown that evolution of the THEXI state persists into the picosecond time range and is not complete on the femtosecond timescale, as previously suggested. These studies have also been extended to cover heteroleptic complexes and the effects of deuteriation and solvent. Ru(II) complexes containing a 1,2,4 - triazole moiety have been investigated using a variety of techniques, including time correlated single photon counting, resonance Raman and transient absorption. At room temperature studies have shown the ability to control the electrochemical and photophysical properties through substitution of the triazole and alternating the symmetrical N N ligands. Low temperature emission and single photon counting (on the microsecond timescale) measurements have shown the presence of two emissions for the 1,2,4 - triazole complexes containing a pyrazine moiety. These studies have highlighted the importance of electron délocalisation and excited state dipole, as well as the relative energies of the ligands, when controlling the excited state location. Throughout the work deuteriation have been employed to considered effect with its application of particular importance to the Raman and excited state lifetime studies. Computational studies have also been used to augment the experimental work. These studies have reveal details about the energy level structures of dual emissive complexes while also highlighting some limitations of calculations preformed in an isolated environment

Synthesis and characterisation of a series of novel mononuclear and surface active dinuclear ruthenium (II) and osmium (II) polypyridyl complexes

The synthesis, spectroscopic and electrochemical characterisation of a series of mononuclear and dinuclear ruthenium (II) and osmium (II) complexes is described. Chapter 1 provides an introduction to the area of supramolecular chemistry. The complex [Ru(bpy)3]2 , the parent complex of modem supramolecular chemistry is also introduced. Chapter 2 is a general introduction to the physical measurements of the complexes which have been synthesised. The techniques of High Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR), UV/Visible spectroscopy, fluorimetry, spectroelectrochemistry and electrochemistry are all briefly described to provide an insight into the application of these techniques later in the thesis. Chapter 3 provides an introduction to the ligands used to synthesise the complexes described in Chapters 3, 4 and 5. The ligands all contain a fused 5 and 6 membered ring, with the 5 membered ring having an imidazo-type functionality in the case of all the ligands with the exception of one, where the 5 membered ring contains a third nitrogen and becomes a triazotype system. The ’H NMR spectra of the ligands have been assigned where possible, and die photophysics and electro chemistry of the free ligands are discussed. The synthesis of a series of novel ruthenium(II) mononuclear complexes, [Ru(bpy)2(LL)j2 is described as is the synthesis of several deuleraled analogues, [Ruic/s-bpyMLL)]2'. The characterisation of these complexes by X-Ray Crystallography and *H NMR is discussed with an isomerisation effect being discussed in detail using analysis from ’H NMR and HPLC experiments. The characterisation of the complexes is completed with an examination of the photophysical, photochemical and electrochemical properties. Chapter 4 is structured similarly. The synthesis of the osmium(II) bipyridyl complexes using the ligands discussed in Chapter 3 is described. The same isomerisation effect appears for several of the ligands and is again discussed in detail. Again, the characterisation of the complexes is completed with an examination of the photophysical, photochemical and electrochemical properties. The LL7 ligand is used to synthesise a ruthenium(II) monomer as well as a series of homonuclear and heteronuclear ruthenium(II) and osmium(n) dimers. The deuterated analogues of the Ru-Ru homonuclear dimer has also been synthesised. These complexes provide the material for discussion in Chapter 5. The photophysical and electrochemical examination of this series of complexes indicates that little or no communication exists between the metal centres, even in the case of the mixed-metal complex. The spectroelectrochemistry of the complexes agree with this supposition. Chapter 6 introduces a different type of complex and a detailed survey of previous work in this area using the bridging ligands 4,4’bipyridyl, P2P, P3P and PEP precedes the discussion of the synthesis and characterisation of the series of mononuclear ruthenium(II) and osmium(II) complexes. It proved important to understand the properties of these compounds as these monomeric species provide the starting material for the synthesis of the series of dimers discussed in Chapter 7. The synthesis and spectroscopic behaviour of this series of dinuclear complexes is presented. The dinuclear complexes have been synthesised with the intention of attaching them to surfaces. This is described for one of the complexes and a brief examination of the behaviour of the complex confined to a surface is performed. The final chapter, Chapter 8 provides a conclusion to the work carried out on the two projects that make up this thesis. The chapter also suggests further work, which may be carried out in future studies