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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Aggregation of photosensitizers: the role of dispersion and solvation on dimer formation energetics

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Bettanin, Fernanda [1] ; de Carvalho Fontinelles, Tancredo Augusto [1] ; Maciel, Cleiton Domingos [1] ; Dias, Luis Gustavo [2] ; Coutinho-Neto, Mauricio Domingues [1] ; Homem-de-Mello, Paula [1]
Total Authors: 6
[1] Univ Fed ABC, ABCSim, Ctr Ciencias Nat & Humanas, BR-09210580 Santo Andre, SP - Brazil
[2] Univ Sao Paulo, Dept Quim, FFCLRP, BR-14040901 Ribeirao Preto, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: THEORETICAL CHEMISTRY ACCOUNTS; v. 134, n. 12 NOV 20 2015.
Web of Science Citations: 6

A detailed account for the dimer formation energetics is computed for two commonly used photosensitizers: metal-free phthalocyanine (Pc) and methylene blue (MB), a cationic phenothiazine. Gas-phase calculations were performed using the density functional theory augmented with dispersion corrections using both the dispersion-correcting atom-centred potentials and the D2/D3 methods. SCS-MP2/CBS results were also provided for comparison. Hydration free energies were determined using continuum methodologies: namely the conductor-like polarizable continuum model, the solvation model density and a reparametrized version of the polarizable continuum model. For methylene blue, the Langevin dipole model was also used. Our results showed that the nature of aggregation is remarkably different for these two molecules, being dispersion driven for Pc while solvent driven for MB. For water and ethanol our results are in good agreement with the experimental data available for MB. We also provide quantitative estimates to the popular explanation put out by Mukerjee and Ghosh more than 40 years ago that aggregation arises from solvent entropic and inter-species enthalpic contributions. (AU)

FAPESP's process: 10/19790-3 - Theoretical study of porphyrins, phthalocyanines and CHLORINES with enphasis for use in photodynamic therapy
Grantee:Fernanda Bettanin
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 12/50680-5 - Photosensitization in life sciences
Grantee:Mauricio da Silva Baptista
Support type: Research Projects - Thematic Grants