@article {1200,
	title = {Size effects of PVP-Pd nanoparticles on the catalytic Suzuki reactions in aqueous solution},
	journal = {Langmuir},
	volume = {18},
	number = {12},
	year = {2002},
	note = {Li, Y Boone, E El-Sayed, MA},
	month = {Jun},
	pages = {4921-4925},
	abstract = {A series of poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized Pd nanoparticles with varying particle size are prepared by using the stepwise growth reaction. The effect of Pd particle size on the Suzuki reaction between phenylboronic acid and iodobenzene is investigated by the use of four Pd catalysts with mean particle sizes of 3.0, 3.9, 5.2, and 6.6 nm, respectively. The catalytic activity of the Pd nanoparticles expressed in terms of the initial turnover frequency (moles of the biphenyl product per mole of total surface Pd atoms per min) is found to be in the order of Pd (3.9 nm) > Pd (3.0 nm) approximate to Pd (5.2 nm) > Pd (6.6 nm), indicating that surface Pd atoms do not all have the same reactivity in this reaction. The general trend of increased catalytic activity with the decrease in the particle size suggests that the low-coordination number vertex and edge atoms on the particle surface are active sites for the Suzuki reaction. The lower catalytic activity for the smallest Pd nanoparticles might be due to stronger adsorption of the reaction intermediates on the particle surface, in which the strongly adsorbed species act as a poison to the reaction thereby decreasing the rate of the reaction.},
	isbn = {0743-7463},
	doi = {10.1021/la011469q},
	author = {Li, Y. and Boone, E. and El-Sayed, Mostafa A}
}
@article {1204,
	title = {Direct observation of charge-transfer dynamics in a conjugated conducting polymer poly (3-octylthiophene)-fullerene composite by time-resolved infrared spectroscopy},
	journal = {Physical Review B},
	volume = {64},
	number = {23},
	year = {2001},
	note = {Wang, JP Li, Y Hong, XY El-Sayed, MA},
	month = {Dec},
	abstract = {Transient infrared-active vibrational (IRAV) modes observed in the pi -conjugated conducting polymers upon photoexcitation are usually used to characterize the dynamics of the photoinduced charge separation and recombination processes. In this paper, the dynamic behavior of photogenerated charge carrier in the poly(3-octylthiophene) (P3OT) conducting polymer doped with fullerene (C(60)) has been studied by using step-scan time-resolved Fourier-transform infrared spectroscopy at room temperature in the 2500-900-cm(-1) (0.31-0.11-eV) frequency region. Upon photoexcitation with a 10-ns laser pulses, it is observed that IRAV modes appear in the similar vibrational frequency regions for pure P3OT and C(60)-doped P3OT; however, the observed IRAV modes is enhanced by 800\% in intensity in the presence of small amount of C(60) (e.g., 10\%). Our results also show that the charge separation occurs instantaneously within the laser pulse width (10 ns), whereas the charge recombination processes occur in the microseconds to a few milliseconds time domain. In addition, the observed enhancement in the IRAV modes upon C(60) doping indicates an enhanced photogeneration efficiency of the charge separation.},
	isbn = {1098-0121},
	doi = {10.1103/PhysRevB.64.235413},
	author = {Wang, Jianping and Li, Y. and Hong, X. Y. and El-Sayed, Mostafa A}
}
@article {1214,
	title = {The effect of stabilizers on the catalytic activity and stability of Pd colloidal nanoparticles in the Suzuki reactions in aqueous solution},
	journal = {Journal of Physical Chemistry B},
	volume = {105},
	number = {37},
	year = {2001},
	note = {Li, Y El-Sayed, MA},
	month = {Sep},
	pages = {8938-8943},
	abstract = {Transition metal nanoparticles used in catalysis in solution are stabilized by capping the surfaces that are supposed to be used for catalysis. Determining, how these two properties, that is, the catalytic activity and stability of nanoparticles, change as different capping materials are used is the aim of this work. Pd nanoparticles prepared by the reduction of metal salts in the presence of three different stabilizers-hydroxyl-terminated poly(amido-amine) (PAMAM) dendrimers (Gn-OH, where Gn represents the nth generation), block copolymer polystyrene-b-poly(sodium acrylate) and poly (N-vinyl-2-pyrrolidone) (PVP)-are used as catalysts in the Suzuki reactions in an aqueous medium to investigate the effects of these stabilizers on the metallic nanoparticle catalytic activity and stability. The stability of the Pd nanoparticles is measured by the tendency of the nanoparticles to give Pd black powder after the catalytic reaction. The Suzuki reaction is a good "acid test" for examining the stability of these nanoparticles, as it takes place when refluxed at about 100 degreesC for 24 h. The stability is found to depend on the type of the stabilizer, the reactant, and the base used in the reaction system. Pd nanoparticles stabilized by block copolymer, G3 dendrimer, and PVP are found to be efficient catalysts for the Suzuki reactions between phenylboronic acid (or 2-thiopheneboronic acid) and iodobenzene. G4 dendrimer is found to be an effective stabilizer; however, strong encapsulation of Pd particles in the dendrimer results in a loss of catalytic activity. The Suzuki reactions between arylboronic acids and bromoarenes catalyzed by Pd nanoparticles result in byproducts due to the homo-coupling of bromoarenes. A summary of the catalytic activity and stability of the Pd nanoparticles in these different systems is tabulated. As one would expect. these two properties are anticorrelated that is the most stable is the least catalytic active.},
	isbn = {1089-5647},
	doi = {10.1021/jp010904m},
	author = {Li, Y. and El-Sayed, Mostafa A}
}
@article {1230,
	title = {Activation energy of the reaction between hexacyanoferrate(III) and thiosulfate ions catalyzed by platinum nanoparticles},
	journal = {Journal of Physical Chemistry B},
	volume = {104},
	number = {47},
	year = {2000},
	note = {Li, Y Petroski, J El-Sayed, MA},
	month = {Nov},
	pages = {10956-10959},
	abstract = {A temperature-dependent study was carried out for the platinum-nanoparticle-catalyzed electron-transfer reaction between hexacyanoferrate(III) and thiosulfate ions in the temperature range of 20-70 degreesC. The Pt nanoparticles are dominantly truncated octahedral in shape and have an average particle size of 7.0 +/- 0.8 nm. The catalyzed reaction is compared with the uncatalyzed reaction in the same temperature range. The activation energy of the reaction is found to be 38.3 +/- 2.0 kJ/mol for the uncatalyzed reaction and 17.6 +/- 0.9 kJ/mol for the catalyzed reaction in the lower temperature range (20-50 degreesC). In the higher temperature range (50-70 degreesC), the rate remains nearly constant. This behavior is attributed to the cancellation of two effects: the temperature dependence of the catalytic reaction and the decrease in the catalyst surface area due to the increase of nanoparticle aggregation.},
	isbn = {1089-5647},
	doi = {10.1021/jp002569s},
	author = {Li, Y. and Petroski, J. M. and El-Sayed, Mostafa A}
}
@article {1231,
	title = {Suzuki cross-coupling reactions catalyzed by palladium nanoparticles in aqueous solution},
	journal = {Organic Letters},
	volume = {2},
	number = {15},
	year = {2000},
	note = {Li, Y Hong, XM Collard, DM El-Sayed, MA},
	month = {Jul},
	pages = {2385-2388},
	abstract = {[GRAPHICS] Palladium nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) are efficient catalysts for the Suzuki reactions in aqueous medium. The time dependence of the fluorescence intensity of the biphenyl product in the reaction between iodobenzene and phenylboronic acid is used to determine the initial rate of the catalytic reaction. The initial rate depends linearly on the concentration of Pd catalyst, suggesting that the catalytic reaction occurs on the surface of the Pd nanoparticles.},
	isbn = {1523-7060},
	doi = {10.1021/ol0061687},
	author = {Li, Y. and Hong, X. M. and Collard, D. M. and El-Sayed, Mostafa A}
}
