Photo Induced Energy And Electron Transfer Reactions In Multinuclear Transition Metal Complexes

Author : 陳國柱
Publisher : Open Dissertation Press
ISBN 13 : 9781374724389
Total Pages : 236 pages
Book Rating : 4.7/5 (243 download)

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Download or read book STUDY OF PHOTOINDUCED ELECTRON written by 陳國柱 and published by Open Dissertation Press. This book was released on 2017-01-27 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Study of Photoinduced Electron Transfer Reactions and Effect of Solvent Interactions on the Photophysical and Photochemical Properties of Dinuclear Au(I), Polynuclear Cu(I) and Cyclometallated Pt(II) Complexes" by 陳國柱, Kwok-chu, Chan, 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 the thesis entitled STUDY OF PHOTOINDUCED ELECTRON TRANSFER REACTIONS AND EFFECT OF SOLVENT INTERACTIONS ON THE PHOTOPHYSICAL AND PHOTOCHEMICAL PROPERTIES OF DINUCLEAR Au(I), POLYNUCLEAR Cu(I) AND CYCLOMETALLATED Pt(II) COMPLEXES submitted by Chan Kwok Chu for the degree of Doctor of Philosophy at The University of Hong Kong in September 1999 Light-intensity and concentration dependence of the photoproduct yield are investigated in a monophotonic process. Relationship of the photoproduct yield with the laser intensity and the complex concentration for a monophotonic process is derived under laser flash photolysis. The relationship is confirmed experimentally in a monophotonic process, i.e., triplet-triplet transition for a Cu(I) complex Cu (DMNSN') . At low light intensity, the relationship can be 6 6 approximated to a linear square root dependence of the light intensity. Based on this equation, a new method is developed to determine the intrinsic back electron transfer rate constant k in photoinduced intermolecular ET reactions, thus ET precluding the effect of diffusional encounter pairs. The Marcus "Inverted Region" has been observed by applying the method to photoinduced back ET reactions of [Au (dppm) ](ClO ) (dppm = bis(diphenylphosphino)methane) with a series of 2 2 4 2 substituted pyridinium acceptors. The photophysical properties of the complexes of the type [Au (dcpm) ]Y, 2 2 2 - - - - - - where Y = ClO, PF, CF SO, Au(CN), Cl and I, dcpm = 4 6 3 3 2 bis(dicyclohexylphosphinomethane) have been studied. A high energy emission at 368 nm has been observed for all these complexes in solid-state and 77K glass - - 3 solution except for Y = Cl and I. This emission is assigned to the [d p ] σ* σemissive state. The low energy solid-state emissions of [Au (dcpm) ](ClO ) and 2 2 4 2 [Au (dcpm) ]I at 515 and 473 nm respectively are attributed to gold-anion 2 2 2 exciplex emission All complexes display low energy emissions between 500-550 nm, and are assigned to the gold-solvent exciplex emissions. These assignments 2+ have been confirmed by ab initio calculations on [Au (H PCH PH ) ] . 2 2 2 2 2 The absorption, emission spectra and lifetimes of [Pt(5-Ph-phen)(CN) ], [Pt(4,4'-Bu -bpy)(CN) ], [Pt(4'-MeOPh-C DEGREESN DEGREESN-phbpy)(py)](PF ) and [Pt(5-Ph- 2 2 6 phen)(ampy) ](CF SO ) have been measured in room temperature solid, 77K 2 3 3 2 solid, 77K glass and room temperature solutions. The emissive states of [Pt(5-Ph- phen)(CN) ] and [Pt(4,4'-Bu -bpy)(CN) ] are assigned to intraligand transition, 2 2 2 whereas that of [Pt(4'-MeOPh-C DEGREESN DEGREESN-phbpy)(py)](PF) and [Pt(5-Ph- phen)(ampy) ](CF SO ) are assigned to metal-to-ligand charge-transfer (MLCT) 2 3 3 2 transitions. Time-resolved absorption measurements have been performed on [Pt(5-Ph-phen)(CN) ] and [Pt(4'-MeOPh-C DEGREESN DEGREESN-phbpy)(py)](PF ), both having 2 6 decaying lifetimes comparable to their MLCT emission. For complexes [Pt(4'- MeOPh-C DEGREESN DEGREESN-phbpy)(py)](PF) and [Pt(5-Ph-phen)(ampy) ](CF SO ), both 6 2 3 3 2 their nonradiative decay rate constants increase exponentially with decreasing nr emission energies, which is in quantitative agreement with the prediction of the energy gap law. Luminescence thermochromism (dual emission) has been observed in complexes (CuNSN')