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Hexanuclear rhenium clusters of the form Re6(u^3-Q8)(PR3)4X2, (Q = Se, S and X = Br- or I- ), and Re6(u^3-Q8)(PR3)4(PEt3)2, where PR3 = tris(4-(4-tert-butylstyrenyl)phenyl)phosphine (PTbs3) have been synthesized and characterized. PTbs3 was chosen for its potential as a two-photon absorbing ligand. Binding of PTbs3 to the cluster core does not completely quench the luminescence of the cluster core. The requirements for Förster energy transfer (FRET) have also been fulfilled. Accessing to the triplet state emission of the cluster core by exciting the PTbs3 ligand using lower-energy light should be achieved. Coumarins substituted at the 6-, 7-, and 8-positions with (phosphine/carbene)gold(I) fragments have also been synthesized in an effort to probe the luminescent properties brought about by a heavy atom such as gold. Each new substituted-coumarin has been characterized by multi-nuclear NMR, elemental combustion analysis, UV-Vis spectroscopy and emissions spectroscopy. In each case, the addition of the gold(I) fragment resulted in the observance of triplet-state emission at room temperature which was not observed for the free coumarin molecule.
Ligand substitution reactions were performed on d 4 rhenium and molybdenum hexanuclear clusters. For the [Re6(3-Q)8] 2+ clusters, where Q= S, Se, varying amounts of tributylphosphine and reaction times yielded multiply substituted clusters. Phosphine substituted reactions were monitored by 31P and 1H NMR as well as mass spectrometry. 31P NMR showed substitution through downfield shifts, for the [Re6S8] 2 clusters, and upfield for that of the [Re6Se8] 2+ clusters from the free tributylphosphine ligand, while mass spectrometry determined the amount of bound phosphines (four or five). Cis-, trans-, and penta-phosphine clusters were generated from these reactions. Triflates replaced apical chlorides on the Mo(II) cluster for increasing lability. A crystal structure was determined from this cluster displaying that of a [Mo6Cl8] 4 core surrounded by six triflate ligands bound through oxygen. Two tetraphenylphosphonium cations are also found with the structure. Base-promoted transmetalation was used to attach phosphine gold(I) fragments to the ends of pyrene. Three new compounds were generated with tricyclohexylphosphine- and triphenylphosphinegold(I) at the 2- and 2,7-positions. 31P and 1H NMR confirm reactions went to completion with no traces of the starting phosphine. Diffraction quality crystals were reported for two of the products. Binding of the phosphine causes a red shifting and increase of the absorbance which is further enhanced with additional gold(I) ligands. Finally, diaurated bithiophene was produced from a boron transmetalation reaction. Triphenylphosphinegold bromide provided a suitable starting ligand for the replacement of terminal boropinacolates on the bithiophene. Reaction monitoring through multinuclear spectroscopy and mass spectrometry determined a diaurated species. A crystal structure allowed visual confirmation of the complex demonstrating the triphenylphosphinegold(I) ligand bound to the carbon adjacent to the sulfur atom. In agreement with aurated pyrenes, phosphine binding both red shifts and increases the absorbance. Further evaluation would enable studies of its optoelectronics properties.
This dissertation, "Design, Synthesis and Characterization of Ruthenium(II) and Rhenium(I) Complexes With Functionalized Ligands for Photo-and Electrochemi- Luminescence, Solvatochromism, Molecular Recognition and HPLC Separation Studies" by Meijin, Li, 李梅金, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled DESIGN, SYNTHESIS AND CHARACTERIZATION OF RUTHENIUM(II) AND RHENIUM(I) COMPLEXES WITH FUNCTIONALIZED LIGANDS FOR PHOTO- AND ELECTROCHEMI- LUMINESCENCE, SOLVATOCHROMISM, MOLECULAR RECOGNITION AND HPLC SEPARATION STUDIES Submitted by LI MEIJIN for the degree of Doctor of Philosophy at The University of Hong Kong in July 2006 A series of ruthenium(II) and rhenium(I) diimine complexes containing thia-, selena- and aza-crowns derived from 1,10-phenanthroline, [Ru(bpy) (phen-3S)](ClO ) 2 4 2 (phen-3S = 1,13-dioxa-4,7,10-trithiacyclopentadecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-2S)](ClO ) (phen-2S = 1,7,10,16-tetraoxa-4,13-dithiacyclohexa- 2 4 2 dodecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-S)](ClO ) (phen-S = 1,4,10,13- 2 4 2 tetraoxa-7-thiacyclopentadecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-Se)](ClO ) 2 4 2 (phen-Se = 1,4,10,13-tetraoxa-7-selenacyclopentadecano[2,3-f][1,10]phenanthroline), [Ru(bpy) (phen-OEt](ClO ) (phen-OEt = 5,6-diethoxy-[1,10]phenanthroline), 2 4 2 [Ru(bpy) (phen-2NH)](ClO ) (phen-2NH = 1,13-diaxa-4,7,10-trioxacyclopenta- 2 4 2 decano[2,3-f][1,10]phenanthroline), [Re(CO) (py)(phen-3S)]PF, [Re(CO) (py)(phen-S)]OTf 3 6 3 and [Re(CO) (py)(phen-Se)]OTf have been synthesized and characterized, and their photophysics, electrogenerated chemiluminescence (ECL) and electrochemistry were studied. Their interaction with metal ions was investigated by UV-vis, luminescence, NMR spectroscopy and ECL. [Ru(bpy) (phen-3S)](ClO ) and [Re(CO) (py)(phen-3S)]
The coordination of benzyl isocyanide to the [Re6Se8]2+ core to produce [Re6Se8(PEt3)5(C≡NCH2Ph)](SbF6)2, an organometallic hexarhenium selenide cluster, is also described. This synthesis is important for the reason that it extends the very limited organometallic chemistry of hexarhenium selenide clusters. In addition, the potential use of isocyanide ligands to produce Fischer carbenes is discussed.