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Luminescent copper (I) and rhenium (I) diimines, and coinage metal chalcogenides

by Lo, Kam-wing

Abstract (Summary)
(Uncorrected OCR) Abstract of thesis entitled "LUMINESCENT COPPER(I) AND RHENIUM(I) DIIMINES, AND COINAGE METAL CHALCOGENIDES"

Submitted by Lo Kam Wing Kenneth for the degree of Doctor of Philosophy

at The University of Hong Kong in September, 1996.

Abstract

A series of copper(I) and silver (I) chalcogenide complexes [Cu4(J,tS)](PF6)2, [Cu4(J,t-dppm)4(J,t4-Se)] (PF6)2, [Ag4(Jl-dppm)4(/l4-S)] (OTf)2, [Ag4(Jldppm)4(Jl4-Se)](OTf)2 and [Ag4(Jl-dppm)4(/-l4-Te)](OT?2 have been synthesized and structurally characterized. All the complexes display long-lived photoluminescence in the solid state and in fluid solutions. The lowest lying excited state of these complexes is assigned to be an admixture of ligandmetal charge transfer [LMCT (E2- ~ M4)] (where E = S, Se, Te) and metalcentred [MC (ds/dp)] character, which has also been supported by both spectroscopic studies and Fenske-Hall molecular orbital calculations. For [Cu4(/l-dppm)4(/l4-Se)](pF6)2, an excited state reduction potential of -1.55(10) V vs. S.S.C.E. has been estimated by Stern-Volmer quenching experiments. The transient absorption difference spectra of the copper(I) complexes and pyridinium salts reveal absorption bands characteristic of the pyridinyl radical together with two additional absorption bands at ca. 480 and 690 nm. The origins of these transitions have been discussed in detail.

A series of dinuclear copper(I) complexes [{Cu(PPh3)2}2(BL)]2+ (BL = dpp, dmdpq, dpq, dcdpq, dpb) have been synthesized, characterized and their photophysical and electrochemical properties studied. Excitation of the

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complexes results in a high energy intraligand sIL emission and a low energy sMLCT emission at ca. 600-750 nm. The observed trends in the MLCT absorption and emission energies are in accord with the n* orbital energy of the diimine ligand BL. The photo-induced electron transfer reaction of [{Cu(PPhs)2}2(dpp)]2+ and methyl viologen has been studied by transient absorption spectroscopy.

A novel crown ether-containing copper(l) diimine complex [Cu(L1)(pPhs)2]+ [where L1 = N5], together with the uncrowned analogue [Cu(L2)(pPhs)2]+ [where L2 = Npyridylmethylene)phenylamine] and the dinuclear counterpart [{Cu(PPh3)2}2(Ls)]2+ [where Ls = N,N'diaminodibenzo-18-crown-6] have been synthesized, characterized and their photophysical and electrochemical properties studied. The crystal structure of [Cu(L1)(pPhs)2]BF4 has also been established by X-ray crystallography. In methanol, the absorption bands of [Cu(Ll)(pPhs)2]+ and [{Cu(PPhs)2}2(Ls)]2+ at ca. 374 nm exhibit a blue-shift in the presence of alkali and alkaline earth metal cations such as sodium, potassium and barium ions. This observation is ascribed to the binding of the cation by the polyether cavities of the complexes, confirmed by electrospray ionization-mass spectrometry (ESIMS). The stability constants for the adducts between the copper(I) crown complexes and selected metal cations have also been determined.

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A senes of rhenium (I) complexes [Re(N-N)(CO)3Cl] (N-N = pmpa, pmfa, pmca, pmaa) and [Re(N-N)(CO)s(Py)]+ (N-N = dppz, dppn) containing an extended planar diimine ligand N-N have been synthesized, characterized, and their photophysical and electrochemical properties studied. The crystal structures of [Re(dppz)(CO)s(py)]OT?and [Re(dppn)(CO)3(Py)]OT?have also been established by X-ray crystallography. The absorption bands of [Re(dppz)(CO)3(py)]+ and [Re(dppn)(CO)3(PY)]+ at ca. 320-420 nm exhibit hypochromism and bathochro'mic shifts in the presence of double-stranded calf thymus DNA, and synthetic oligonucleotides poly(dA).poly(dT) and poly(dC}poly(dG). This observation, together with the selective enhancement in emission intensities of the complexes in the presence of poly(dA)?oly(dT) suggest that the complexes bind to the DNA duplex by intercalation.

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Bibliographical Information:

Advisor:

School:The University of Hong Kong

School Location:China - Hong Kong SAR

Source Type:Master's Thesis

Keywords:copper compounds ruthenium chalcogenides

ISBN:

Date of Publication:01/01/1997

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