Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/41708
Title: Insights into the Photophysics and Supramolecular Organization of Congo Red in Solution and the Solid State
Authors: Costa, Ana L. 
Gomes, Ana C. 
Pillinger, Martyn 
Gonçalves, Isabel S. 
Pina, João 
Seixas de Melo, J. Sérgio 
Issue Date: 2017
Project: Fundação para a Ciência e a Tecnologia. Grant Numbers: PEst-OE/QUI/UI0313/2014 
Fundação para a Ciência e a Tecnologia. Grant Numbers: FCOMP-01-0124-FEDER-029779 
Fundação para a Ciência e a Tecnologia. Grant Numbers: PTDC/QEQ-SUP/1906/2012 
Fundação para a Ciência e a Tecnologia. Grant Numbers: POCI-01-0145-FEDER-007679 
Fundação para a Ciência e a Tecnologia. Grant Numbers: UID/CTM/50011/2013 
Fundação para a Ciência e a Tecnologia. Grant Numbers: SFRH/BD/88806/2012 
Fundação para a Ciência e a Tecnologia. Grant Numbers: SFRH/BPD/108541/2015 
Fundação para a Ciência e a Tecnologia. Grant Numbers: SFRH/BPD/108469/2015 
Serial title, monograph or event: ChemPhysChem
Volume: 18
Issue: 5
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 (≈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 ≈170 ps 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.
URI: http://hdl.handle.net/10316/41708
DOI: 10.1002/cphc.201601236
Rights: embargoedAccess
Appears in Collections:FCTUC Química - Artigos em Revistas Internacionais

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