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Synthesis and properties of covalently linked thiaporphyrin-ferrocene conjugates

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Title Synthesis and properties of covalently linked thiaporphyrin-ferrocene conjugates
 
Creator LAKSHMI, V
SANTOSH, G
RAVIKANTH, M
 
Subject BENZO CROWN-ETHER
MESO-TETRAFERROCENYLPORPHYRIN
ELECTROCHEMICAL PROPERTIES
PORPHYRIN ARRAYS
REDOX
MOLECULES
DICATIONS
SWITCHES
MOIETIES
Thiaporphyrins
Ferrocene
Electron transfer
Non-fluorescent
Oxidation
 
Description Four examples of ferrocene-thiaporphyrin conjugates in which the ferrocenyl group was covalently connected either directly at meso-position of thiaporphyrin or to meso-phenyl group of thiaporphyrin via ethyne bridge were prepared by coupling bromo- or iodo thiaporphyrin with alpha-ethynylferrocene under mild Pd(0) coupling conditions. NMR, absorption and electrochemical studies indicated that the thiaporphyrin and ferrocenyl units interact strongly in ethyne bridged porphyrin-ferrocene conjugates but the interaction is very weak in phenyl ethyne bridged porphyrin-ferrocene conjugates. The steady state fluorescence studies indicated that the fluorescence yields are reduced to 50% in phenyl ethyne conjugates but the fluorescence is completely quenched in ethyne bridged conjugates. The partial or complete quenching of porphyrin fluorescence in these conjugates is due to electron transfer from ferrocene unit to excited state of porphyrin sub-unit. Oxidation of ferrocene to ferrocenium ion with an oxidizing agent in ethyne bridged conjugates resulted in a recovery of porphyrin fluorescence. (C) 2010 Elsevier B.V. All rights reserved.
 
Publisher ELSEVIER SCIENCE SA
 
Date 2012-01-20T10:07:13Z
2012-01-20T10:07:13Z
2011
 
Type Article
 
Identifier JOURNAL OF ORGANOMETALLIC CHEMISTRY,696(4)925-931
0022-328X
http://dx.doi.org/10.1016/j.jorganchem.2010.10.028
http://dspace.library.iitb.ac.in/jspui/handle/100/13818
 
Language English