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Please use this identifier to cite or link to this item: http://hdl.handle.net/2031/4727

Title: Utilisation of luminescent cyclomentallated iridium (III) polypyridine complexes as biological labelling reagents and probes
Other Titles: Ju fa guang xing huan jin shu hua yi duo bi ding luo he wu zuoJu fa guang xing huan jin shu hua yi duo bi ding luo he wu zuo wei sheng wu biao ji shi ji ji tan ce qi zhi ying yong
具發光性環金屬化銥多吡啶絡合物作為生物標記試劑及探測器之應用
Authors: Chung, Chi Keung (鍾自強)
Department: Department of Biology and Chemistry
Degree: Doctor of Philosophy
Issue Date: 2005
Subjects: Chemical tests and reagents
Luminescent probes
Iridium
Notes: Thesis (Ph.D.)--City University of Hong Kong, 2005
Includes bibliographical references (leaves 364-379)
xi, 379 leaves : ill. ; 30 cm.
CityU Call Number: QD77.C57 2005
Type: Thesis
Abstract: A family of thirty luminescent cyclometallated iridium(llI) diimine complexes with different functionalised diimine ligands [Ir(N-C)2(N-N)](PF6) has been synthesised and characterised. The X-ray crystal structures of [ I r ( m ppz)2 ( bpy - N H 2 ) ] ( P F 6),[lr( ppy)2(bpy-CHO)](PF6) and [Ir(mppz)2(bpy-CHO)](PF6) have been determined. Upon irradiation, all the complexes displayed intense and long-lived luminescence under ambient conditions and in 77-K glass. On the basis of the photophysical and electrochemical data, the emission of most of these complexes is assigned to an excited state of predominant triplet metal-to-ligand charge-transfer ( 3 MLCT) (dπ(lr)π*(N-N)) character. In some cases, triplet intraligand (3lL) (ππ*)(N-N or N-C-) excited states have also been identified. In view of the specific reactivity of the isothiocyanate and iodoacetamide moieties towards the primary amine and sulfhydryl groups, respectively, various biological molecules have been labelled with a selection of these luminescent iridium(ll1) complexes. The photophysical properties of the luminescent conjugates have been investigated. In addition, a heterogeneous assay for digoxin has also been designed based on the recognition of biotinylated anti-digoxin by avidin that has been labelled with one of the luminescent iridium(ll1) complexes. Four luminescent cyclometallated iridium(lll) complexes containing two aldehyde functional groups [lr(pba)2(N-N)](PF6) have been synthesised, characterised and their photophysical and electrochemical properties studied. The X-ray crystal structure of [Ir(pba)2(bpy)](PF6) has been investigated. Upon photoexcitation, these complexes exhibited intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The luminescence is assigned to an 3lL excited state associated with the pbaligand, probably with mixing of some 3MLCT(dπ(lr) π(pba-)) character. Since each of these complexes possesses two aldehyde groups, which can react with the primary amine groups of biomolecules to form stable secondary amines after reduction, the possibility of these complexes as luminescent cross-linkers for biological substrates has been investigated. In this connection, L-alanine has been cross-linked with these complexes to give luminescent bioconjugates. These conjugates showed strong photoluminescence with long emission lifetimes under ambient conditions. On the basis of the emission energy trend, the excited state of these luminescent bioconjugates is supposed to bear a high parentage of 3~~~~ (dπ(lr)  π*(N-N)) character. In addition, the glycoprotein avidin has also been cross-linked with these complexes to give new bioconjugates. Upon photoexcitation, these bioconjugates displayed intense and long-lived 3~~~~ (dπ (lr) π*(N-N)) emission in aqueous buffer at 298 K. Furthermore, a heterogeneous competitive assay for biotin has been developed using one of the luminescent avidin conjugates and biotinylated microspheres. Six cyclometallated iridium(lll) diimine complexes equipped with a biotin moiety [Ir(N-C)2(bpy-en-biotin)](PF6) have been synthesised and characterised. The photophysical and electrochemical properties of these complexes have also been studied. Upon photoexcitation, these complexes displayed intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The emission is assigned to an 3MLCT (dπ (lr)  π*(bpy-en-biotin)) excited state. However, the excited state of [Ir(pq)2(bpy-en-biotin)](PF6)i s likely to possess substantial 3 lL (π π*)(pq-) character. The binding of these iridium(lll) biotin complexes to avidin has been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, emission titrations and competitive assays using native biotin. Homogeneous competitive assays for biotin have also been designed. A series of luminescent cyclometallated iridium(ll1) complexes containing different intercalating ligands [Ir(ppy)2(N-N)](PF6) has been synthesised, characterised and their photophysical and electrochemical properties studied. The X-ray crystal structure of [lr(ppy)2(dppz)](PF6) has been determined. Upon photoexcitation, the complexes displayed long-lived green to orange luminescence under ambient conditions and in alcohol glass at 77 K. The intercalative binding of these complexes to double-stranded calf thymus DNA and synthetic oligonucleotides poly(dA)-poly(dT) and poly(dG)-poly(dC) has been studied by spectroscopic titrations. The avidin-binding properties of the biotin-containing complexes have also been investigated by absorption and emission titrations.
Online Catalog Link: http://lib.cityu.edu.hk/record=b1988744
Appears in Collections:BCH - Doctor of Philosophy

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