abstract
Zn-Al layered double hydroxides (LDHs) containing solely indigo carmine (IC) or 1-hexanesulfonate (HS) anions, or a mixture of the two with different HS/IC molar ratios, were prepared by the direct synthesis method and characterized by various techniques. Hydrotalcite-type phases were obtained with basal spacings of 17.6 angstrom for the LDH intercalated by IC (IC-LDH) and 18.2-18.3 angstrom for the other materials containing HS. From the basal spacing for IC-LDH and UV/Vis spectroscopic data, it is proposed that the dye molecules assemble within the interlayer galleries to form a J-type stacking arrangement. A comprehensive electronic spectral and photophysical study was undertaken for IC in solution and all materials, aiming to obtain a detailed characterization of the host-guest and guest-guest interactions. In solution (the solvent surrounded isolated molecule), IC presents a fast excited state proton transfer with rate constants of approximate to 1.2-1.4x10(11)s(-1), which is linked to the very efficient radiationless deactivation channel. In the solid state it is shown that incorporation of IC within the LDH decreases the level of aggregation, and that further addition of HS induces the appearance of isolated IC units within the LDH galleries. The indigo carmine-based nanocomposites reported constitute a step forward in the design of hybrid materials with tunable properties.
keywords
LAYERED DOUBLE HYDROXIDE; EXCITED-STATE CHARACTERIZATION; PHOTOPHYSICAL CHARACTERIZATION; POLARIZED PHOTOLUMINESCENCE; INTERCALATION COMPOUNDS; ANIONIC DYE; HYDROTALCITE; DYNAMICS; LUMINESCENCE; CHROMOPHORES
subject category
Chemistry
authors
Costa, AL; Gomes, AC; Pillinger, M; Goncalves, IS; de Melo, JSS
our authors
Ana Catarina Costa Gomes Alves
Assistant Researcher
Ana Luísa Costa
Researcher
Isabel Maria de Sousa Gonçalves
Associate Professor
Martyn Pillinger
Principal Researcheracknowledgements
We acknowledge funding by FEDER (Fundo Europeu de Desenvolvimento Regional) through COMPETE (Programa Operacional Factores de Competitividade). National funding through the FCT (Fundacao para a Ciencia e a Tecnologia) within the projects Coimbra Chemistry Centre (FCT ref. UID/QUI/00313/2013), and FCOMP-01-0124-FEDER-029779 (FCT ref. PTDC/QEQ-SUP/1906/2012, including the research grant BPD/UI89/4864/2013 to A.C.G.) is thanked. This work was developed in the scope of the project CICECO - Aveiro Institute of Materials (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. The FCT is acknowledged for a doctoral grant to A.L.C. (ref. SFRH/BD/88806/2012).