Samuel C' Lind Lectures, East Tennessee ACS Chapter, Univ Tenn'

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Samuel C. Lind Lectures, East Tennessee ACS
Chapter, Univ Tenn. GOLDEN QUANTUM DOTS
SYNTHESIS, ANALYSIS, ELECTROCHEMISTRY Royce W.
Murray UNC Chapel Hill, NC STORIES OF METAL
NANOPARTICLES WITH DEFINED CHEMICAL
FORMULAE, QUANTIZED ELECTROCHEMICAL PROPERTIES
AND A VARIETY OF CHEMICAL BEHAVIORS MONOLAYER
PROTECTED CLUSTERS (MPCs) SIZE DEPENDENT
ELECTROCHEMISTRY Au38 MOLECULE-LIKE, WITH A
HOMO-LUMO GAP EVIDENT Au140 A QUANTUM
CAPACITOR, NO HOMO-LUMO GAP DUAL
DETECTOR CORE SIZE ANALYSIS IN REVERSED PHASE
HPLC ELECTRON HOPPING IN A NANOPARTICLE
POLYMER FILM AND ITS APPLICATION IN VAPOR
SENSING NSF, ONR, DOE
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THEMES OF NANOPARTICLE RESEARCH AT UNC TREAT
SMALL NANOPARTICLES, NEAR THE METAL-MOLECULE TRANS
ITION AS NEW KINDS OF MOLECULES, WITH
MOLECULAR FORMULAE SYNTHESIS OF MONODISPERSE
MATERIALS NEEDS FOR NEW ANALYTICAL
CHARACTERIZATION UNDERSTAND THEIR CHEMISTRY ON
A MOLECULAR LEVEL THE POLYMER CHEMISTRY OF
NANOPARTICLES ASSESS ELECTRONIC STRUCTURE
ASSESS THEIR ELECTRON TRANSFER DYNAMICS
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MPC SYNTHESIS
(RSH)
BH4-
RSSR
reduction
phase transfer
reduction
growth
passivation
PRODUCT IS USUALLY POLYDISPERSE
f(T, RSH)
f(T, RSH)
Auo nucleation
MPC DISPERSITY REFERS TO THE UNIFORMITY
(MONODISPERSE) OR LACK OF UNIFORMITY (POLYDISPERSE
) OF THE MPC CORE (SIZE, SHAPE, ATOMS) AND OF
ITS MONOLAYER (KIND AND LIGANDS, LOCATION ON
CORE SURFACE). PROCEDURES FOR FRACTIONATION
SOLUBILITY/EXTRACTION, ELECTROPHORESIS,
CHROMATOGRAPHY ANALYTICAL TOOLS TO MEASURE
DISPERSITY TEM, EC-LC, GPC, UV-VIS
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MOLECULAR FORMULAS FOR NANOPARTICLES
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Au38(SCH3)24 Häkkinen, H. Barnett, R. N.
Landman, U. Phys. Rev. Lett. 1999, 82, 3264-3267
Au140(C6)53
1.6nm Au trunc octahedron 96 surface Au 44
internal (SHOWN NAKED)
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ISOLATION OF Au38(PhC2S)24 MPCs
THE -SCH2CH2Ph LIGAND GIVES THE MPC SOLUBILITY
PROPERTIES FAVORABLE FOR SOLVENT FRACTIONATION
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TEM OF Au38(PhC2S)24 MPCs DIA. 1.11 ?0.32
Au(38) dia 1.11 ?0.32
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For the MeCN-soluble fraction Au38(PhC2)24(Oct4NBr
)1.5 EXPT CALCD organic fraction by
TGA 32.8 33.4 elemental analysis
SULFUR 7.0 6.6 CARBON 25.2
24.8
 
Thermogravimetric analysis
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8556
TOF-MS, MATRIX FREE N2 LASER PULSE
Core size of 38 Au Atoms is most abundant Core
size of 79 Au atoms also present
14668
16478
Jimenez, Langmuir, 2004, 20, 6864-6870
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MPC VOLTAMMETRY AND THE METAL-MOLECULE TRANSITION
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ELECTRON TRANSFERS OF MPCs
SIZE DEPENDENT ELECTROCHEMISTRY QUANTIZED
DOUBLE LAYER CHARGING MOLECULE-LIKE HOMO-LUMO
GAP
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Voltammetry of 1.9 mM Au38(PhC2S)24 0.1 M
Bu4NPF6 in CH2Cl2 at 0.4 mm-dia. Pt electrode
DPV 25OC 20 mV/s DPV -70OC 20 mV/s
CV -70OC 100 mV/s
EREST O2
D. Lee, J. Amer. Chem. Soc, 2004, 126, 6193
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1.36 eV
eV
D. Lee, J. Amer. Chem. Soc, 2004, 126, 6193
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MODEL ENERGY LEVEL DIAGRAM FOR Au38(PhC2S)24 From
electrochemical, optical absorbance and
photoluminesence data
1.22 eV 1020 nm 1.38 eV 902 nm 1.36 eV 910
nm 1.80 eV 690 nm
 
0.3

0.3
LUMO
0.3
1.62 EGAP ECHG
1.36 EGAP
1.80

1.22
1.32
PL EDGES 1.77, 0.89
1.38 EPL
HOMO
0.3
0.44
PL (eV)
0.7
OPTICAL (eV)
ECHEM (eV)
GENERAL FEATURES 1.3 eV HOMO-LUMO ANOTHER
DISTINCT LEVEL BELOW HOMO NEAR CONTINUUM DOS
ABOVE LUMO SUB-GAP ENERGY PL PROBABLY
ASSOCIATED WITH SURFACE-LOCALIZED ENERGY STATES
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QUANTIZED DOUBLE LAYER CHARGING Au140SC653
ONE-ELECTRON TRANSFERS SPACED BY ?V e /
CMC CONCENTRIC SPHERE CAPACITOR MODEL
CCLU 4???o (r/d) (rd) CCLU 5.6x10-19 F
and ?V e/CCLU 285 mV from ? 3 , r 0.8 nm,
d 0.77 nm
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Chen, J. Physical Chemistry B, 1998, 102, 9898
VOLTAMMETRY FOR CHARGING THE QUANTUM CAPACITOR
IS A SERIES OF ONE ELECTRON WAVES
CV AT RT
Miles, Anal. Chem. 2003, 75, 1251-1257
Hicks, J. Am. Chem. Soc. 2002, 124, 13322
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UNPUBLISHED WORK THAT IS NOT RELEASED TO WEBCAST
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AN ELECTROCHEMICAL ENERGY DIAGRAM FOR MPCs
HOMO-LUMO GAPS Au75 0.4 eV (est.) Au38
1.3 eV Au11 1.5 eV (est)
RELATIVE POTENTIALS OF ELECTROCHEMICAL CHARGING
0.7V
1.6V
0.2V
0.3V
1.8V
?
Aux
Au205
Au140
METALLIC, CONTINUUM DOS
Au75
METAL- LIKE, QUANTIZED CHARGING
??Au55
Au38
MOLECULE-LIKE ENERGY GAP
Au11
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DUAL DETECTOR HPLC OF NANOPARTICLES
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REVERSED PHASE HPLC HAS MUCH HIGHER RESOLVING
POWER THAN GEL PERMEATION CHROMATOGRAPHY AND
YIELDS MORE DETAIL FOR SMALL NANOPARTICLES THAN
PREVIOUS LITERATURE DEVELOPING A NEW ANALYTICAL
ROUTE TO NANOPARTICLE SIZE DETERMINATION BASED ON
DUAL DETECTORS AND REVERSED PHASE HPLC (r
CORE RADIUS, d MONOLAYER) OPTICAL ABSORBANCE
ABS. ? r3 MICROCHANNEL ELECTRODE ILIM ?
D2/3 ?? 1/(rd)2/3 ABS./iLIM ?
r3(rd)2/3 ? r11/3 ALSO CAN GET r FROM
QUANTIZED DL CHARGING ?V e/4???O(r/d)(rd)

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DEVELOPING A NEW ANALYTICAL ROUTE TO NANOPARTICLE
SIZE DETERMINATION A SAMPLE OF NOMINALLY
Au140(SC6)53

PEAK RADIUS RADIUS FROM FROM
?V ABS/CUR 1
1.0 NM 2 1.6
1.6 3 1.8 1.7 4 1.9
1.8 5 1.8 1.7
Au140C653 STANDARD r 0.8, d 0.8nm
?V
PEAK 3 CURRENTS
Song, ANALYT CHEM, 2003, 76, 4911
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A HIGHER RESOLUTION SEPARATION OF Au38(SC6)24
Au0
Au1
Energy (eV)
serial two-column chromatogram of a Au38(SC6)24
MPC sample, following its isolation from a silica
column FOUR COMPONENTS, MAJOR ONES ARE Au0 AND
Au1
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UNPUBLISHED WORK THAT IS NOT RELEASED TO WEBCAST
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CHANGING FUNCTIONALITY OF MONOLAYER-PROTECTED
CLUSTERS
POLYMERS WITH METALLIC CONSTITUENTS, PEPTIDES
ELECTRONIC COUPLING TO CORE
C4-22
S
COUPLING RXNS ESTER AMIDE SN2 !
S
S
PLACE-EXCHANGE
S
MULTIPLE COPIES OF SPIN LABEL
CHROMOPHORE FLUOROPHORE AMINO ACID PEPTIDE
NUCLEOTIDE ET D/A LIGAND IONOPHORE
-OH, -COOH -Br, -CN -Fc , -AQ
1.2-4.5 NM
POLY-DISPERSE MONO-DISPERSE
EXAMPLE Au314(SC8)62 (SC3SAQ)16 (SC8OOCFc)12
EXAMPLE Au145(SC6)50 d 1.6 NM
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USING LIGAND EXCHANGE AND METAL COORDINATION TO
MAKE FUNCTIONAL MPCS AND POLYMER
FILMS INTERCALATION AND ELECTROSTATIC LABELING
OF DNA AN ATTEMPT TO CONTROL Au-Au HOPPING
DISTANCE MEASURING THE ELECTRON HOPPING
CONDUCTIVITY MAKING A VAPOR SENSOR
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ELECTROSTATIC BINDING OF Au3000(SC11N(CH3)3)910
TO DNA AS A SOLUBLE COMPLEX TEM IMAGES
Nano Lett. 2004, 4, 95-101
AFM IMAGE OF ETHIDIUM IN MIXED MONOLAYER MPC
INTERCALATING INTO DNA Anal. Chem. 2002, 74,
4320
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MAKING POLYMER FILMS OF MPCs WITH COORDINATIVE
CROSS-LINKING
ELECTRON HOPPING CONDUCTIVITY OF FILMS ON
IDAS CONDUCTIVITY a RATE CONSTANT
Wuelfing, Zamborini, J. Amer. Chem. Soc. 2000,
122, 11465 2002, 124, 8958
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UV-Vis Spectra of MPC Films on Glass as
a Function of Non-Linker Chain Length
Electronic Conductivity of MPC Films on IDA as a
Function of Non-Linker Chain Length
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Effect of Non-Linker Chainlength on Beta Plot
?EL(n,T) ?0exp-n?nexp-EA/RT
Interdigitation
-8
? 0.77/C ( ) ? 0.38/C
-9
-10
-11
FULL
lnsEL (W-1cm-1)
-12
Electron tunneling through methyl terminated
non-linker component
-13
-14
NONE
-15
2
4
6
8
10
12
14
(4)
(8)
(12)
(16)
(20)
(24)
(28)
Average Au MPC Spacing ( of Carbons)
NON-LINKER INTERDIGITATION IS SUPPORTED BY
DENSITY, TEM, AND OTHER CONDUCTIVITY
MEASUREMENTS THE LINKING CHEMISTRY FAILS TO
CONTROL Au Au DISTANCE
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I-V Curves of a C4/MUA MPC Film in Various Pure
Liquids
ELECTRON TRANSPORT IS BY HOPPING BETWEEN
NANO- PARTICLES I-V SLOPE GIVES THAT RATE THE
LIQUID DEPENDENCE SUGGESTS PARTITIONING AND
SWELLING MAKE IT INTO A VAPOR SENSOR!
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C6/MUA FILMS ON IDA WITH 0.2V BIAS AND ON Au/QCM
CRYSTAL. EXPOSED TO PURE N2 AND ETOH AT 0.1,
0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, AND 1.0
OF SATURATED

Cu K 465 Zn K 349 Ag K 284
Faraday Discussions 2003, 125, 63-77
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MONOLAYER PROTECTED CLUSTERS WHAT YOU WOULD LIKE
TO KNOW!
THE MONOLAYER

• What metals
• What alloys
• Size
• Shape
• of atoms
• Dispersity
• Capacitance
• Metallic or molecular

• Chain order
• (solid vs solution)
• Gradient of chain density
• Similarity of ligands
• Surface mobility
• Dielectric characteristics
• Other ligands

THE CORE
FUNCTIONAL GROUPS

• Kinds of groups
• How many per MPC
• Mixtures
• Dispersity
• Reactivity relative to
• free molecules
• Poly-electron transfers

• Intracluster interactions
• (lateral and trans-core)
• Design of multi-functional
• reagents, catalysts
• Excited state behavior
• (lifetimes, reactivity, and
• photoconductivity)

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ACKNOWLEDGEMENTS MICHAEL LEOPOLD (PD) ROBERT
DONKERS (PD) FRANK ZAMBORINI (PD) DONGIL LEE
(PD) DIMITRA GEORGANOUPOULOU (PD)
BALASUBRANAMIAN RAMJEE (PD) YANG (JULIA) SONG
GANGLI WANG VICTORIA JIMENEZ JOCELYN
HICKS AMANDA HARPER REBECCA WOLFE RUI GUO DEON
MILES PAWEL KULESZA (UNIV. WARSAW) STEPHEN
FELDBERG (BROOKHAVEN NL) ONR, NSF,
DOE