MilliporeSigma
  • Home
  • Search Results
  • Mechanistic insight into the formation of cationic naked nanocrystals generated under equilibrium control.

Mechanistic insight into the formation of cationic naked nanocrystals generated under equilibrium control.

Journal of the American Chemical Society (2014-10-11)
Sean E Doris, Jared J Lynch, Changyi Li, Andrew W Wills, Jeffrey J Urban, Brett A Helms
ABSTRACT

Cationic naked nanocrystals (NCs) are useful building units for assembling hierarchical mesostructured materials. Until now, their preparation required strongly electrophilic reagents that irreversibly sever bonds between native organic ligands and the NC surface. Colloidal instabilities can occur during ligand stripping if exposed metal cations desorb from the surface. We hypothesized that cation desorption could be avoided were we able to stabilize the surface during ligand stripping via ion pairing. We were successful in this regard by carrying out ligand stripping under equilibrium control with Lewis acid-base adducts of BF3. To better understand the microscopic processes involved, we studied the reaction pathway in detail using in situ NMR experiments and electrospray ionization mass spectrometry. As predicted, we found that cationic NC surfaces are transiently stabilized post-stripping by physisorbed anionic species that arise from the reaction of BF3 with native ligands. This stabilization allows polar dispersants to reach the NC surface before cation desorption can occur. The mechanistic insights gained in this work provide a much-needed framework for understanding the interplay between NC surface chemistry and colloidal stability. These insights enabled the preparation of stable naked NC inks of desorption-susceptible NC compositions such as PbSe, which were easily assembled into new mesostructured films and polymer-nanocrystal composites with wide-ranging technological applications.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Acetone, histological grade, ≥99.5%
Sigma-Aldrich
N,N-Dimethylformamide, ReagentPlus®, ≥99%
Sigma-Aldrich
N,N-Dimethylformamide, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99.8% (GC)
Sigma-Aldrich
1,4-Dioxane, ACS reagent, ≥99.0%
Sigma-Aldrich
N,N-Dimethylformamide, biotech. grade, ≥99.9%
Sigma-Aldrich
Acetone, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99.5% (GC)
Sigma-Aldrich
1,4-Dioxane, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99.5% (GC)
Sigma-Aldrich
Octane, reagent grade, 98%
Sigma-Aldrich
1,4-Dioxane, suitable for HPLC, ≥99.5%
Sigma-Aldrich
Acetone, suitable for HPLC, ≥99.9%
Sigma-Aldrich
Acetone, suitable for HPLC, ≥99.8%
Sigma-Aldrich
1,4-Dioxane, ReagentPlus®, ≥99%
Sigma-Aldrich
N,N-Dimethylformamide, suitable for HPLC, ≥99.9%
Sigma-Aldrich
Acetone, HPLC Plus, for HPLC, GC, and residue analysis, ≥99.9%
Sigma-Aldrich
Acetone, ACS reagent, ≥99.5%
Sigma-Aldrich
Acetone, puriss., meets analytical specification of Ph. Eur., BP, NF, ≥99% (GC)
Sigma-Aldrich
N,N-Dimethylformamide, ACS reagent, ≥99.8%
Sigma-Aldrich
Acetone, ACS reagent, ≥99.5%
Sigma-Aldrich
Acetone, Laboratory Reagent, ≥99.5%
Sigma-Aldrich
1,4-Dioxane, ACS reagent, ≥99.0%
Sigma-Aldrich
Octane, puriss. p.a., ≥99.0% (GC)
Sigma-Aldrich
Octane, electronic grade, ≥99.999% metals basis, ≥99% (CP)
Supelco
Ethanol solution, certified reference material, 2000 μg/mL in methanol
Sigma-Aldrich
N,N-Dimethylformamide-d7, ≥99.5 atom % D, contains 1 % (v/v) TMS
Sigma-Aldrich
Boron trifluoride, electronic grade, ≥99.99%
Sigma-Aldrich
Octane, anhydrous, ≥99%
Sigma-Aldrich
Diphenylphosphine, 98%
Sigma-Aldrich
Selenium, powder, −100 mesh, ≥99.5% trace metals basis
Sigma-Aldrich
N,N-Dimethylformamide, ACS reagent, ≥99.8%
Sigma-Aldrich
Selenium, pellets, <5 mm, ≥99.99% trace metals basis