Abstract
This paper describes the ordering of PbS nanocubes (NCs) within free-standing monolayers (suspended on acetonitrile), upon exchanging the native oleate ligands for a series of thiolate and carboxylate ligands at the liquid-air interface. Treatment with either carboxylic acids or thiols effectively decreases the inter-NC separation of nearest-neighbor particles without etching the NC surface. Dicarboxylic acids and dithiols bridge neighboring NCs with an interparticle separation that is consistent with fully extended, bridging ligands. Monocarboxylic acids and monothiols separate NCs by an amount governed by their length, with long-chain ligands showing significant intercalation. 1H NMR spectroscopy shows carboxylic acids are more effective at replacing the native oleate than are thiols, which we ascribe to the lower pKa values of carboxylic acids. The fast exchange that occurs upon treatment with monocarboxylic acids kinetically traps the clusters of particles in nonclosed packed geometries, so monolayers treated with monocarboxylic acids are, on average, less ordered than those treated with monothiols. Ex situ electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) analyses of deposited films on Si/SiO2 substrates show that NCs exchanged with nonbridging ligands pack more efficiently at long length scales than do NCs exchanged with bridging ligands, due primarily to the creation of defects within the NC lattice in response to the rigidity of the bridging ligand.
| Original language | English |
|---|---|
| Pages (from-to) | 6666-6673 |
| Number of pages | 8 |
| Journal | Langmuir |
| Volume | 32 |
| Issue number | 26 |
| DOIs | |
| Publication status | Published - Jul 5 2016 |
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ASJC Scopus subject areas
- Electrochemistry
- Condensed Matter Physics
- Surfaces and Interfaces
- Materials Science(all)
- Spectroscopy
Cite this
Structural Features of PbS Nanocube Monolayers upon Treatment with Mono- and Dicarboxylic Acids and Thiols at a Liquid-Air Interface. / McPhail, Martin R.; Campbell, Gavin P.; Bedzyk, Michael J.; Weiss, Emily A.
In: Langmuir, Vol. 32, No. 26, 05.07.2016, p. 6666-6673.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structural Features of PbS Nanocube Monolayers upon Treatment with Mono- and Dicarboxylic Acids and Thiols at a Liquid-Air Interface
AU - McPhail, Martin R.
AU - Campbell, Gavin P.
AU - Bedzyk, Michael J.
AU - Weiss, Emily A
PY - 2016/7/5
Y1 - 2016/7/5
N2 - This paper describes the ordering of PbS nanocubes (NCs) within free-standing monolayers (suspended on acetonitrile), upon exchanging the native oleate ligands for a series of thiolate and carboxylate ligands at the liquid-air interface. Treatment with either carboxylic acids or thiols effectively decreases the inter-NC separation of nearest-neighbor particles without etching the NC surface. Dicarboxylic acids and dithiols bridge neighboring NCs with an interparticle separation that is consistent with fully extended, bridging ligands. Monocarboxylic acids and monothiols separate NCs by an amount governed by their length, with long-chain ligands showing significant intercalation. 1H NMR spectroscopy shows carboxylic acids are more effective at replacing the native oleate than are thiols, which we ascribe to the lower pKa values of carboxylic acids. The fast exchange that occurs upon treatment with monocarboxylic acids kinetically traps the clusters of particles in nonclosed packed geometries, so monolayers treated with monocarboxylic acids are, on average, less ordered than those treated with monothiols. Ex situ electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) analyses of deposited films on Si/SiO2 substrates show that NCs exchanged with nonbridging ligands pack more efficiently at long length scales than do NCs exchanged with bridging ligands, due primarily to the creation of defects within the NC lattice in response to the rigidity of the bridging ligand.
AB - This paper describes the ordering of PbS nanocubes (NCs) within free-standing monolayers (suspended on acetonitrile), upon exchanging the native oleate ligands for a series of thiolate and carboxylate ligands at the liquid-air interface. Treatment with either carboxylic acids or thiols effectively decreases the inter-NC separation of nearest-neighbor particles without etching the NC surface. Dicarboxylic acids and dithiols bridge neighboring NCs with an interparticle separation that is consistent with fully extended, bridging ligands. Monocarboxylic acids and monothiols separate NCs by an amount governed by their length, with long-chain ligands showing significant intercalation. 1H NMR spectroscopy shows carboxylic acids are more effective at replacing the native oleate than are thiols, which we ascribe to the lower pKa values of carboxylic acids. The fast exchange that occurs upon treatment with monocarboxylic acids kinetically traps the clusters of particles in nonclosed packed geometries, so monolayers treated with monocarboxylic acids are, on average, less ordered than those treated with monothiols. Ex situ electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) analyses of deposited films on Si/SiO2 substrates show that NCs exchanged with nonbridging ligands pack more efficiently at long length scales than do NCs exchanged with bridging ligands, due primarily to the creation of defects within the NC lattice in response to the rigidity of the bridging ligand.
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U2 - 10.1021/acs.langmuir.6b01444
DO - 10.1021/acs.langmuir.6b01444
M3 - Article
VL - 32
SP - 6666
EP - 6673
JO - Langmuir
JF - Langmuir
SN - 0743-7463
IS - 26
ER -