Syntheses and spectroscopic studies of luminescent surfactant rhenium(I) and ruthenium(II) diimine complexes : potential applications as functional materials for second-harmonic generation and mesoporous silicate formation
Abstract of thesis entitled
SYNTHESES AND SPECTROSCOPIC STUDIES OF LUMINESCENT SURFACTANT RHENIUM(I) AND RUTHENIUM(II) DIIMINE COMPLEXES- POTENTIAL APPLICATIONS AS FUNCTIONAL MATERIALS FOR SECOND-HARMONIC GENERATION AND
MESOPOROUS SILICATE FORMATION
submitted by ZHANG JIA XIN
for the Degree of Doctor of Philosophy at The University of Hong Kong in July 2004
A series of novel rhenium(I) tricarbonyl diimine complexes fac-[ClRe(CO)3(L)] (L = substituted 4,5-diazafluorene ligands) (1-2), fac-[XRe(CO)3(L)] (L = N-substituted pyridine-carbaldimine ligands, X = Br of" CI) (6-10 and 15-20), fac-[Re(CO)3(N02-phen)(L)]X (N02-phen = 5-nitro-l,10-phenanthroline, L = substituted pyridyl ligands, X = OTf or PFe) (21-23) and^ac-
[Re(CO)3(N-N)L]PF6 (N-N = dioctadecyl ester of 4,4'-dicarboxy-2,2'-bipyridine or 4,7-dinonadecyl-l,10-phenanthroline, L = pyridyl or 4,4'-bipyridyl) (24-27) have been synthesized. Some novel ruthenium(II) diimine complexes [Ru(bpy)2L](PF6)2 (L = substituted 4,5-diazafluorene ligands) (3-5) and novel ruthenium(II) polypyridyl complexes [Ru(N-N)2L]Cl2 (N-N = 2,2'-bipyridine, L = substituted 2,2 -bipyridine ligands) (28-31) have also been prepared. The structures of complexes /ac-[ClRe(CO)3(L)] (L = A^-(4-biphenyl)pyridine-2-carbaldimine) (6), fac-[BrRe(CO)3(L)] (L = (5-Octadecyloxy)-2-pyridine-JV-[4-(4'-decyloxy)-biphenyl]-carbaldimine) (10) and [Ru(bpy)2L](PF6)2 (L = 7V-(4-biphenyl)pyridine-2-carbaldimine) (11) were determined by X-ray crystallography.
The Langmuir-Blodgett (LB) film-forming properties of some complexes were studied by pressure-area (it-A) isotherms. In general, charged complexes possess better hydrophilicity and as a result show good LB film-forming and deposition behavior. The second-harmonic generation (SHG) behavior of some complexes in LB films has also been investigated. It was found that strong second-harmonic generation intensities are usually associated with good film-forming properties, small energy gap for the metal-to-ligand charge transfer transition of the complex, as well as the conjugation length of the molecule.
The mesomorphism and thermal behavior of ./ac-[XRe(CO)3(L)] (L - TV-substituted pyridine-carbaldimine ligands, X = Br or CI) and their corresponding free ligands have been studied by thermogravimetric analysis (TGA), differential
scanning calorimetry (DSC) and polarizing optical microscopy (POM). These compounds were shown to have good thermal stability with decomposition temperature up to ca. 320-402 ?, some of which were shown to display thermotropic liquid-crystalline (LC) properties.
Finally, the liquid-crystalline properties of ruthenium(II) polypyridyl complexes were studied by POM and it was found that these complexes show lyotropic liquid-crystalline behavior in water. The solubility of the complexes is one of the factors that influence the formation of lyotropic LC phases. Using these complexes to serve as template for the synthesis of mesoporous materials by the true liquid crystal templating (TLCT) approach were also studied.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:rhenium compounds synthesis ruthenium transition metal complexes surface active agents photochemistry
Date of Publication:01/01/2005