Composition of molecular aggregates during film formation revealed using simulated absorption spectra

2018 ◽  
Author(s):  
Kelly S. Wilson ◽  
Cathy Y. Wong ◽  
Morgan L. Sosa ◽  
Rima B. Pandit
Keyword(s):  
Absorption Spectra ◽  
Film Formation ◽  
Molecular Aggregates

Electronic absorption spectra of substituted phthalocyanines in solution and as films

2003 ◽  
Vol 07 (08) ◽  
pp. 551-557 ◽  
Author(s):  
Hiroshi Ogata ◽  
Ryuji Higashi ◽  
Nagao Kobayashi
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Film Formation ◽  
Polar Solvents

The electronic absorption spectra of several phthalocyanines substituted at the so-called α-, β- and α and β-positions of the macrocycle have been recorded in solution and as films (α = 1,4,8,11,15,18,22, and 25 positions or 1,8 (or 11),15 (or 18), and 22 (or 25) positions, and β = 2,3,9,10,16,17,23, and 24 positions or 2,9 (or 10),16 (or 17), and 23 (or 24) positions). Phthalocyanines substituted with bulky groups at the α-positions prevent cofacial aggregation so that their Q-absorption band remains at a similar wavelength both in solution and films, although the film spectra are generally broader. Phthalocyanines substituted at the β-positions are apt to aggregate cofacially in polar solvents but in films they may show broad Q-bands which spread out to both shorter and longer wavelengths of the solution Q-band, depending on the bulkiness of the substituents. The film spectra of hexadeca-substituted phthalocyanines exhibit Q-bands at a similar wavelength as in solution, with insignificant broadening of the Q-band on film formation. However, the Soret bands for most of the substituted phthalocyanines are shifted and broadened to longer wavelength in the films.

Sign in / Sign up

Export Citation Format

Share Document