Tuning the Behavior of a Hydrotalcite-Supported Sulfonated Bithiophene from Aggregation-Caused Quenching to Efficient Monomer Luminescence


The synthesis, electronic spectral, and photo-physical properties of a new bithiophene derivative, (2,2'-bithiophene)-3,5,5'-trisulfonic acid, alpha 2-SO3H, were investigated in organic or aqueous solution, in neat oil form, and in the solid state by cointercalation with different amounts of the surfactant 1-heptanesulfonate (HS) into a layered double hydroxide (LDH). In solution the fluorescence quantum yield (phi(F)) of alpha 2-SO3H increases by 1 order of magnitude when compared to the unsubstituted bithiophene (alpha 2) counterpart. However, the most dramatic change is obtained when alpha 2-SO3H is incorporated with HS into a Zn,Al-LDH, where values of phi(F) up to 58% are obtained in comparison with values of 4% for neat alpha 2-SO3H (as an oil) and 2% for an LDH containing only alpha 2-SO3H. In the solid state (LDH), in addition to the monomeric form of alpha 2-SO3H, H- and other types of aggregates are present, which are found to be dependent on the percentage HS content. Time-resolved fluorescence studies further rationalize this behavior with single and double exponential decays mirroring the contributions of monomers and aggregates. The study validates a strategy of increasing fluorescence in the solid state by introduction of electrodonating groups and isolation of the alpha 2-SO3H units within the LDH structure with an appropriate surfactant (HS).



subject category

Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary


Delgado-Pinar, E; Costa, AL; Goncalves, IS; Pineiro, M; Pillinger, M; de Melo, JSS

our authors


This work was carried out with the support of Centro de Quimica de Coimbra [FCT (Fundacao para a Ciencia e a Tecnologia) Ref Nos. UIDB/00313/2020 and UIDP/00313/2020], CICECO -Aveiro Institute of Materials [FCT Ref Nos. UIDB/50011/2020 and UIDP/50011/2020], the COMPETE 2020 Operational Thematic Program for Competitiveness and Internationalization (Project Hylight, 02/SAICT/2017, PTDC/QUI-QFI/31625/2017), the CENTRO 2020 Regional Operational Programme (Project SASCOT, 02/SAICT/2017, PTDC/QUI-QOR/28031/2017), cofinanced by national funds through the FCT/MCTES and the European Union through the European Regional Development Fund (ERDF) under the Portugal 2020 Partnership Agreement. The research leading to these results has received funding from Laserlab-Europe (Grant Agreement No. 284464, EC's Seventh Framework Programme). E.D.-P. thanks the Concurso de Estimulo ao Emprego Cientifico for the Junior Contract CEECIND/04136/2018. The NMR spectrometers of the University of Aveiro are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No. 022161 (cofinanced by the EDRF through COMPETE 2020, POCI and PORL, and the FCT through PIDDAC). NMR data collected at the UC-NMR facility are supported in part by the EDRF through the COMPETE Program and by national funds from the FCT through Grants RECI/QEQ-QFI/0168/2012 and CENTRO-07-CT62-FEDER-002012 and also through support to Rede Nacional de Ressonancia Magnetica Nuclear (RNRMN) and to Coimbra Chemistry Centre through Grant UID/QUI/00313/2019.

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