Monolayers in Three Dimensions: NMR, SAXS, Thermal, and Electron Hopping Studies of Alkanethiol Stabilized Gold Clusters

Terrill, Roger H.; Postlethwaite, Timothy A.; Chen, Chun‐Hsien; Poon, Chi‐Duen; Terzis, Andreas; Chen, Aidi; Hutchison, James E.; Clark, Mike; Wignall, G. D.

doi:10.1021/ja00155a017

Cited by 835 publications

(943 citation statements)

References 1 publication

Supporting

Mentioning

837

Contrasting

Order By: Relevance

“…The amount of interpenetration is roughly proportional to the thiol chain length (here C8, 12, and 16) and the inter-nanocrystal spacing quite less than twice the thiol chain length. 26 This is concurrent with thiol chain interdigitation and agrees with our previously measured inter-nanocrystal spacings for silver NCSs. 2,18 Direct imaging and simultaneous chemical composition analysis of Ag nanocrystal interconnects within a NCS was achieved using energy-filtering TEM.…”

supporting

confidence: 91%

High-Temperature Stability of Passivated Silver Nanocrystal Superlattices

Harfenist

Wang

1999

J. Phys. Chem. B

View full text Add to dashboard Cite

Ordered arrays of ∼4.5 nm diameter silver nanocrystals passivated with dodecanethiol show remarkable thermal stability at temperatures up to 975 K. Defects in the ordered-assembly were the first areas to show signs of melting while much of the structure remained intact. The mechanism for their stability is attributed to the unusually strong inter-nanocrystal bond formed by the interpenetration of thiol chains between neighboring nanocrystals within the nanocrystal superlattice. Individually dispersed nanocrystals show stability up to 800 K while some persist until 975 K.The potential application of nanoscale materials in fields ranging from biology to electronics has spurred remarkable interest and investigation into the preparation and characterization of identical, isolated, nanometer-scale entities composed of materials such as metals, 1,2 semiconductors, 3 magnetic materials, 4 and a wide variety of others. 5,6 Applications in catalysis and biological tagging 7 and the possibility of nanometer-sized magnetic domains for ultrahigh-density recording media 4 are just a few of their many possible uses. The subsequent organization of identical passivated nanometer-scale objects into micron-scale ordered arrays gives encouragement to the use of these novel materials particularly in regards to their collective nonlinear optical properties where stability at high temperatures is necessary. 8 The studies of nanometer-sized crystallites over the past twenty years and more recently their composite structures have been numerous. 9,10 Various methods are being used to produce these materials in such abundance as to allow their characterization by means of well-known chemical and physical techniques. 6,11,12 The solution phase, gas (aerosol) phase, and reverse-micelle methods have been the most popular nanocrystal production techniques lately.An important factor in the production of nanocrystals is the ability to keep them physically isolated from one another. Many different types of systems have been used for nanocrystal passivation as well as exchange of one surfactant for another. 3,7,13 Factors such as the binding energy of the headgroups to the nanocrystal surface, 14 how the exposed tails affect the solubility and reactivity of the passivated nanocrystal (i.e., its functionality), 10 the effect of the passivation agent on the electronic and optical properties of the nanocrystal core, the electronic properties of the surfactant material itself, 15 and, further, the agent's ability to bind or link nanocrystals together both structurally and electronically [16][17][18] are all very important conditions placed on a material that will allow the nanocrystal to be stable and isolated yet not affect its core material's properties. Here we present an in-situ temperature analysis of the aforementioned nanocrystals and their superlattices and show that not only do individual passivated silver nanocrystals supported on an amorphous carbon film remain stable at temperatures near 800 K, but also that the silver nanocrystal superc...

show abstract

supporting

confidence: 91%

High-Temperature Stability of Passivated Silver Nanocrystal Superlattices

Harfenist

Wang

1999

J. Phys. Chem. B

View full text Add to dashboard Cite

show abstract

“…1d,e. The abrupt change in slope in C p around 200 K is the result of a glassy transition of the oleate ligands 10,11 , as these unsaturated hydrocarbon tails do not crystallize at the nanocrystal surface. In contrast, the CdSe NCAs capped with long saturated hydrocarbon chains (that is, n-tetradecylphosphonic acid) can form ordered domains at the nanocrystal surface, indicated by sharp peaks in the DSC curves in Supplementary Fig.…”

mentioning

confidence: 99%

Surface chemistry mediates thermal transport in three-dimensional nanocrystal arrays

et al. 2013

View full text Add to dashboard Cite

Arrays of ligand-stabilized colloidal nanocrystals with sizetunable electronic structure are promising alternatives to single-crystal semiconductors in electronic, optoelectronic and energy-related applications 1-5 . Hard/soft interfaces in these nanocrystal arrays (NCAs) create a complex and uncharted vibrational landscape for thermal energy transport that will influence their technological feasibility. Here, we present thermal conductivity measurements of NCAs (CdSe, PbS, PbSe, PbTe, Fe 3 O 4 and Au) and reveal that energy transport is mediated by the density and chemistry of the organic/inorganic interfaces, and the volume fractions of nanocrystal cores and surface ligands. NCA thermal conductivities are controllable within the range 0.1-0.3 W m −1 K −1 , and only weakly depend on the thermal conductivity of the inorganic core material. This range is 1,000 times lower than the thermal conductivity of silicon, presenting challenges for heat dissipation in NCA-based electronics and photonics. It is, however, 10 times smaller than that of Bi 2 Te 3 , which is advantageous for NCA-based thermoelectric materials.Colloidal nanocrystals self-assemble into NCAs with electronic and optical properties that can be broadly tuned by nanocrystal composition and size 1-4,6-8 . To be considered as viable replacements for traditional semiconductors, NCA-based technologies must also meet thermal management demands as high operating temperatures degrade device performance and lifetime. Thermal conductivity (k) quantifies a material's ability to dissipate heat and relates temperature gradient (∇T ) to heat flux (q) through Fourier's law, q = −k∇T . In metals, most heat is carried by electrons, whereas in semiconductor and insulating crystals, thermal conductivity arises from the transport and scattering of quantized vibrations that are born from the periodic atomic lattice, that is, phonons. Our NCAs are non-metallic and have a vibrational structure that is complicated by compositional heterogeneity and periodicity at two length scales: the atomic lattice within each core and the array of periodic cores separated by ligand monolayers. Studies of planar self-assembled monolayer (SAM) junctions show that surface chemistry can control energy transport at the interface between two solids 9 , but does it also influence the thermal conductivity of a bulk three-dimensional solid with a complex network of internal interfaces? We herein report on the hitherto unknown thermal transport properties of NCAs, using systematic thermal conductivity measurements complemented by heat capacity measurements and atomistic simulations.A series of NCAs was prepared with varying core diameters, core materials and ligand groups (Table 1) through spin-coating concentrated colloidal solutions onto silicon wafers 6 . During film

show abstract

“…A 61.8-ml toluene solution of tetra-n-octyl ammonium bromide (0.0358 M) was added to a vigorously stirred 30-ml 0.0288 M aqueous solution of AuClO 4 . After 1 h of stirring, a 71.4 ml 0.015 M toluene solution of DPTTF was added and the resulting solution was stirred for 10 min.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, monolayers self-assembled on small, well-defined metal clusters (3D SAMs) have received a great deal of attention because of their diverse physico-chemical properties and potential utility in wide range of technologies (2)(3)(4). The presence of higher monolayer concentration owing to the large surface area of the metal clusters as well as the fact they are soluble in various organic solvents make it possible to apply various analytical techniques like NMR, UV-VIS, and XRD on them which is difficult for the corresponding 2D monolayers (4).…”

Section: Introductionmentioning

confidence: 99%

Charge-Transfer Complexation of C60 with Diphenyltetrathiafulvalene (DPTTF) Capped Gold Clusters

Resmi

Sandhyarani

Unnikrishnan

et al. 1999

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

4,4 -Diphenyltetrathiafulvalene (DPTTF) capped gold nanoparticles of 3-to 5-nm diameter have been prepared and their thermal stability has been investigated by variable temperature FT-IR spectroscopy. The DPTTF molecules at the cluster surface undergo charge-transfer complexation with C 60 to form Au/ DPTTF.C 60 . Direct evidence of complexation is observed in the x-ray photoelectron and infrared spectra of the clusters. The orientational ordering transition of C 60 in Au/DPTTF.C 60 clusters occur at a higher temperature than pure C 60 indicating increased resistance to orientational disorder due to charge transfer. Variable-temperature infrared spectroscopic studies yield complementary information. Both FT-IR and mass spectra show that some of the sites on the gold surface are occupied by the phase-transfer reagent used in the cluster preparation.

show abstract

Monolayers in Three Dimensions: NMR, SAXS, Thermal, and Electron Hopping Studies of Alkanethiol Stabilized Gold Clusters

Cited by 835 publications

References 1 publication

High-Temperature Stability of Passivated Silver Nanocrystal Superlattices

High-Temperature Stability of Passivated Silver Nanocrystal Superlattices

Surface chemistry mediates thermal transport in three-dimensional nanocrystal arrays

Charge-Transfer Complexation of C60 with Diphenyltetrathiafulvalene (DPTTF) Capped Gold Clusters

Contact Info

Product

Resources

About