Supplemental Information
1. Figure S1: Snapshot of a single C18 ligand capped nanocrystal. Size of the nanocrystal is 4 nm.
Coverage density is about 4 ligands/nm2.
a)
b)
c)
d)
2. Figure S2: Snapshots of 3 nm NC with different ligand coverage densities. a) 2.5 ligands/nm2, b)
3 ligands/nm2, c) 3.5 ligands/nm2 and d) 4 ligands/nm2.
3. Figure S3: Graph of Interaction Energy Curve vs ligand capping density for a 3.1 nm
Nanocrystal.
4. Figure S4: Graph of Interaction Energy Curve vs ligand length for a 3.1 nm Nanocrystal.
5. Figure S5: Differential scanning calorimetry of 7 nm nanocrystal capped with C18 oleic acid
ligands with a coverage of about 3.0 ligands/nm2. The various curves are for different processing
solvents in the lattice. A peak in the curves would indicate a phase transition such as melting or
boiling. The only peak seen is for toluene at around 100 ˚C. This corresponds to evaporation of
residual toluene in the superlattice. If there were ligand bundling, and the bundles underwent a
melting transition from bundled to un-bundled state, there would be a peak observed in the
specific heat capacity curve with temperature. No such peak is seen until 120 ˚C. It is therefore,
unlikely that ligands are strongly bundled. (The small dips that are seen around 60 ˚C are due to
some trapped hexane in the lattice since all the NC samples were initially dissolved in hexane and
then processed in other solvents.)
6.
Bond
CH2-CH2
CH2-CH3
Angle
CH2-CH2-CH2
CH2-CH2-CH3
Dihedral
CH2-CH2-C2-CH2
CH2-CH2-C2-CH3
Non-bonded Interactions
CH2
CH3
r0 (Å)
1.54
1.54
θ0 (˚)
109.5
109.5
K1 (kcal/mol)
1.412
1.412
σ (Å)
3.90
3.90
K [kcal/(mol/Å2)]
260
260
K´ [kcal/(mol/deg2)]
63
63
K2 (kcal/mol)
-0.272
-0.272
ε (kcal/mol)
0.12
0.175
Table I Force Field Parameters for the Jorgensen United Atom Model [1].
K3 (kcal/mol)
3.15
3.14
7.
Bond
CH2-CH2
CH2-CH3
Angle
CH2-CH2-CH2
CH2-CH2-CH3
Dihedral
CH2-CH2-C2-CH2
CH2-CH2-C2-CH3
Non-bonded Interactions
CH2
CH3
r0 (Å)
1.53
1.53
θ0 (rad)
1.92
1.92
k1 (kcal/mol)
1.6
1.6
σ (Å)
4.009
4.009
k [kcal/(mol/Å2)]
634
634
k´ [kcal/(mol/deg2)]
120
120
k2 (kcal/mol)
-0.867
-0.867
ε (kcal/mol)
0.09344
0.22644
k3 (kcal/mol)
3.24
3.24
Table II Force Field parameters for the Paul et al. United Atom Model [2].
References:
[1] W. L. Jorgensen, J. D. Madura and C. J. Swenson, J. Am. Chem. Soc., 106, 6638-6646 (1984)
[2] W. Paul, Do Y. Yoon and G.D. Smith, J. Chem. Phys. (1995) 103, 1702-1709