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Title: Design of new sensor platforms for molecular recognition
Author: Montgomery, H. J.
ISNI:       0000 0004 2723 0295
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2012
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A series of bipyridine and pyridine ligands have been prepared and fully characterised. These are 5- bromobutyr-2,2'-bipyridine (L 1), (2,2'-Bipyridin-5-ylmethyl)-5-(1 ,2-dithiolan-3-yl)pentanoate (L2) N-(2,2'- bipyridin-5-ylmethyl)-5-(1 ,2-dithiolan-3-yl)pentanamide (L3), pyridin-3-ylmethyl-5-(1,2-dithiolan-3- yl)pentanoate (L4) pyridin-4-ylmethyl-5-(1 ,2-dithiolan-3-yl)pentanamide (LS) and ethyl 5-(1,2-dithiolan-3- yl)pentanoate (L6). Their Re(l) and RU(lI) complexes have also been prepared and characterised in most cases. The photophysical properties of these complexes have been investigated showing expected intense . emission. The behaviour of a variety of these ligands and complexes has been studied on a colloidal silver surface, analysed by Surface Enhanced (Resonance) Raman Spectroscopy (SE(R)RS). Concentration dependent behaviour was observed for L2 and L3. A relatively low intensity of the SERS signal at the highest concentrations was attributed to a combination of interference of fluorescence from species in solution and high surface coverage of the nanoparticles preventing the formation of silver-bipyridine complexes. At the optimum concentration we propose the formation of silver-bipyridine complexes which display a resonance enhanced component of the SERS signal. At lower concentrations a simple lack of substrate capable of giving a signal results in a reduction in the observed peak intensity again. Similar behaviour was also observed for the respective rhenium(l) complexes, [Re(COh(L2)Br] and [Re(COh(l3) Br] while preliminary work also indicated the same behaviour in the charged rhenium(l) complexes [Re(COh(bpy)(py)f and [Re(COh(bpy)(LS)r. These insights may enable the development of the system for future sensing applications. Complex [Re(COh(L2)Br] and [Re(COh(bpy)Br] showed selective changes in its photophysical properties in the presence of Hg2+ ions when experiments were carried out in acetonitrile solution. Detailed studies of the system suggest that an exchange of the Br ligand fora CH3CN ligand takes place through an intermediate species, with formation of the charged complex [Re(COh(L2)(CH3CN)f and [Re(COh(bpy) (CH3CN)1 irrespective of the counter-ion (either CI04- or N03-). Similar behaviour was not observed with a range of other metal cations.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available