Gold nanoparticles in the range of 5-6 nm were synthesized by the reduction of gold(III) chloride trihydrateby sodium borohydride (SBH) in the presence of newly synthesized mono-6-deoxy-6-pyridinium-
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BORDER=
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0 ALIGN="middle">CD). NMR, mass spectroscopy, and UV-vis spectroscopy illustrated that SBH wouldsimultaneously reduce both p-
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0 ALIGN="middle">CD and gold salt even though the reduction of the latter occurs more rapidly.Resulting gold nanoparticles were capable of oxidizing the reduced p-
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0 ALIGN="middle">CD-gold complex via hydrogen bonding and ionic interaction. Gold nanoparticles were synthesized froma much higher concentration (1.
0 mM vs
0.25 mM in the absence of p-
![](/images/<font color=)
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0), acetate, citrate, and borate. The p-
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0 ALIGN="middle">CD-goldnanoparticle assembly displayed intensified fluorescence with emission at 498 nm when excited at 47
0 nm,a phenomenon known as metal-enhanced fluorescence. The gold nanoparticles acted as electron acceptorsand controlled the pathways of the excited-state deactivation. Surface binding of the pyridinium moiety ofp-
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0 ALIGN="middle">CD to gold nanoparticles suppressed the intramolecular photoinduced electron transfer from the lone pairof the nitrogen atom to the aromatic ring and thereby increased the efficiency of radiative deactivation, leadingto a fluorescence enhancement. The p-
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0 ALIGN="middle">CD-gold nanoparticle system could be exploited for variousfluorescence chemosensing and biosensing schemes, especially for applications demanding long observationtimes without photobleaching.