|
authors |
Costa, AL; Gomes, AC; Pillinger, M; Goncalves, IS; Pina, J; de Melo, JSS |
|
nationality |
International |
|
journal |
CHEMPHYSCHEM |
|
author keywords |
aggregation; congo red; intercalations; layered double hydroxides; photophysics |
|
keywords |
LAYERED DOUBLE HYDROXIDES; AGGREGATION-INDUCED EMISSION; AMYLOID-BETA-PEPTIDE; SOLVATION DYNAMICS; ENERGY-TRANSFER; DYE MOLECULES; AZO-DYE; COMPLEX; BINDING; FILMS |
|
abstract |
Steady-state and time-resolved absorption and fluorescence measurements are reported for Congo Red (CR) in aqueous and dimethylsulfoxide (DMSO) solutions. The very low fluorescence quantum yield (approximate to 10(-4)) for CR in dilute solutions together with the absence of a triplet state indicates that internal conversion is the dominant deactivation route with more than 99.99% of the quanta loss (attributed to the energy gap law for radiationless transitions). Although no direct evidence for trans-cis photoisomerization was obtained from absorption or fluorescence data, the global analysis of fs-transient absorption data indicates the presence of a photoproduct with a lifetime of approximate to 170ps that is suggested to be associated with such a process. Spectral data for more concentrated CR solutions indicate the presence of oblique or twisted J-type aggregates. These results are compared with spectra for CR in the solid state (sodium salt) and intercalated in a layered double hydroxide via a one-step co-precipitation route. Powder XRD and electronic spectral data for the nanohybrid indicate that the CR guest molecules are intercalated as a monolayer consisting of slipped cofacial J-type aggregates. |
|
publisher |
WILEY-V C H VERLAG GMBH |
|
issn |
1439-4235 |
|
year published |
2017 |
|
volume |
18 |
|
issue |
5 |
|
beginning page |
564 |
|
ending page |
575 |
|
digital object identifier (doi) |
10.1002/cphc.201601236 |
|
web of science category |
Chemistry, Physical; Physics, Atomic, Molecular & Chemical |
|
subject category |
Chemistry; Physics |
|
unique article identifier |
WOS:000395423100016
|
