Aggregation of Photosensitisers: the role of dispersion and solvation on
dimer formation energetics
F. Bettanin, T.A.C. Fontinelles, C.D. Maciel, L.G. Dias, M.D. Coutinho Neto,
P. Homem-de-Mello
SUPPORTING INFORMATION
Molecular dynamics was used as a tool to investigate the behavior of dimers in
solution. Emphasis was placed in the orientation dynamics between monomers. To
this aim, a vector was defined whose endpoints were set connecting the hydrogen
atoms bound to the pyrrole ring. The left panel in Figure SI1 shows the angular
distribution between the vectors for each monomer with the most probable
configurations for Pc being 10, 45 and 90 degrees. For MB, a vector was defined
connecting the nitrogen and sulphur atoms of the molecule central ring. The angular
distribution obtained for MB shows a clear preference for anti-parallel dimers similar
to the MBanti conformation (see Figure 2).
Figure SI1. Angle distribution between photosensitizers molecules in dimeric form in
aqueous solution. At left we have the angle distribution of MB (blue) and at right Pc (red).
1
Table SI1. Solvation free energy contributions obtained in water, ethanol and diethylether for
the Pc45 dimer configuration at BLYP/DGDZVP level
CPCM
Water
Monomer
Dimer
Monomer
G0gsolv,el/ kcal mol-1
-18.1
-11.1
-26.1
-18.0
G
-1
47.5
11.3
2.5
2.1
-1
-15.9
-9.8
-24.5
-17.0
-1
0
gsolv,cd/
G
Ethanol
G
Diethylether
SMD
Dimer
gsolv,el/
0
gsolv,cd/
G
G
0
0
gsolv,el/
0
gsolv,cd/
kcal mol
kcal mol
29.9
1.5
-12.0
-8.9
-1
-7.5
-4.6
-16.1
-11.4
-1
34.7
7.1
-24.4
-19.4
kcal mol
kcal mol
kcal mol
Table SI2. CPCM continuum model free energy terms for Pc monomer and Pc45 dimer
configuration obtained at BLYP(UAKS)/DGDZVP level
CPCM term
1SASA/
Ethanol
Diethylether
523
521
577
58.4
43.1
45.7
-1
-55.6
-48.7
-45.1
-1
8.5
7.1
6.6
736
725
762
-1
113.4
88.2
88.8
G0gsolv,disp/ kcal mol-1
-77.7
-68.0
-63.0
G0gsolv,rep/
11.7
9.7
8.8
3
G0gsolv,cav/
kcal mol
G0gsolv,disp/
4
G
0
gsolv,rep/
G
0
gsolv,cav/
kcal mol
kcal mol
SASA/
Dimer
Water
-1
2
Monomer
Å2
Å2
kcal mol
kcal mol
-1
1
SASA = solvent accessible surface area;2Cavitation term; 3Dispersion term;4Repulsion
term.
Table SI3. Basis set dependence of the electrostatic free energy contribution as exemplified
for MB in aqueous solution using SMD model at BLYP level
G0gsolv,el/ kcal mol-1
DGDZVP
def2-svp
def2-tzvpp
Dimer (a)
-137.1
-133.1
-135.9
Monomer (b)
-48.4
-46.1
-47.7
Total (a-2*b)
-40.3
-40.9
-40.5
2
Table SI4. Solvation free energy contributions obtained in water, ethanol and diethylether for
the MBanti configuration at BLYP/DGDZVP level
CPCM
Water
Ethanol
Diethylether
SMD
Dimer
Monomer
Dimer
Monomer
-1
-126.2
-41.4
-137.1
-48.4
-1
21.3
2.6
8.4
4.4
-1
-120.8
-39.8
-131.1
-46.2
-1
8.4
-3.0
-4.1
-2.3
G0gsolv,el/ kcal mol-1
-88.1
-27.7
-94.0
-32.8
G0gsolv,cd/ kcal mol-1
14.5
0.6
-9.4
-5.9
G
G
gsolv,el/
0
gsolv,cd/
G
G
0
0
gsolv,el/
0
gsolv,cd/
kcal mol
kcal mol
kcal mol
kcal mol
Table SI5. CPCM continuum model free energy terms for MB monomer and MBanti dimer
configuration obtained at BLYP(UAKS)/DGDZVP level
CPCM term
1SASA/
G0gsolv,cav/
2
Monomer
G
4
Dimer
0
gsolv,rep/
Ethanol
Diethylether
330
330
358
34.7
25.6
27.0
-1
-39.6
-52.0
-48.2
-1
7.5
6.2
5.6
kcal mol
kcal mol
Water
-1
kcal mol
G0gsolv,disp/
3
Å2
SASA/ Å2
503
498
530
G0gsolv,cav/ kcal mol-1
69.5
51.2
54.2
G0gsolv,disp/ kcal mol-1
-59.5
-34.7
-32.1
G
11.3
9.3
8.5
0
gsolv,rep/
kcal mol
-1
1
SASA = solvent accessible surface area;2Cavitation term; 3Dispersion term;4Repulsion term.
3
Table SI6. Solvation free energy difference obtained in ethanol and diethylether for the more
stable configurations of MB and Pc at BLYP/DGDZVP level
Model
G0gsolv,el/
G0gsolv,cd/
G0gsolv/
kcal mol-1
kcal mol-1
kcal mol-1
MBanti
CPCM/Ethanol
-41.2
14.4
-26.8
CPCM/Diethylether
-32.7
13.4
-19.3
SMD/Ethanol
-38.7
0.5
-38.2
SMD/Diethylether
-28.3
2.4
-25.9
G0gsolv,el/
G0gsolv,cd/
G0gsolv/
kcal mol-1
kcal mol-1
kcal mol-1
CPCM/Ethanol
3.6
26.9
30.5
CPCM/Diethylether
1.7
20.5
22.2
SMD/Ethanol
9.5
5.8
15.3
SMD/Diethylether
6.8
14.4
21.2
Pc45
Model
4