Insights into the Photophysics and Supramolecular Organization of Congo Red in Solution and the Solid State
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
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journal impact factor 2.947
5 year journal impact factor 2.950
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