An Indigo Carmine‐Based Hybrid Nanocomposite with Supramolecular Control of Dye Aggregation and Photobehavior

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 Å for the LDH intercalated by IC (IC-LDH) and 18.2-18.3 Å 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 ∼1.2-1.4×10(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.

Effect of Chlorophyll Hybrid Nanopigments from Broccoli Waste on Thermomechanical and Colour Behaviour of Polyester-Based Bionanocomposites

“…The addition of hydrotalcite, with or without CD, to the INZEA matrix resulted in the modification of the polymer microstructure, since some agglomeration was observed probably caused by the interaction between both nanofillers (the intrinsic inorganic filler present in the INZEA structure and HT nanoclay), with some indications of a partial intercalation/exfoliation, particularly when CD was present (Figure 9b,c). These results could be explained when considering the anionic character of the surfactant used, since its addition into the HT together with CD would result in the delamination of the nanoclay platelets and the consequent modification of the nanocomposite structure, as observed for other anionic dyes [56]. A similar behaviour was observed for MMT-based bionanocomposites (Figure 9d-f), where the presence of partially intercalated/exfoliated structures after the addition of MMT-based CDNPs was obtained.…”

Insights into the Photophysics and Supramolecular Organization of Congo Red in Solution and the Solid State

“…The slip angle α (as defined in Figure b) is about 50° in this model, which is in the range (0–54.7°) conventionally associated with J‐type aggregates (as opposed to H‐type aggregates with α>54.7°) . Examples of organic chromophores that have been proposed to adopt this type of guest packing when intercalated in LDHs include perylene derivatives, 1,3,6,8‐pyrenetetrasulfonate, and indigo carmine …”

“…Instrumental details for elemental analyses (C, H, N and S), PXRD, SEM, TGA, FT‐IR spectroscopy, and solid‐state 13 C{ 1 H} cross‐polarization magic‐angle spinning NMR have been described previously . Raman spectra were recorded on a Bruker RFS100/S FT instrument (Nd:YAG laser, 1064 nm excitation, InGaAs detector).…”

“…Instrumental details and procedures for recording the UV/Vis and fluorescence spectra have been described previously . For solution samples, dimethylsulfoxide (DMSO) was of spectroscopic or equivalent grade and was used as received.…”

Coexistence of 1 : 1 and 2 : 1 inclusion complexes of indigo carmine

“…It has also been used as an electrode material for rechargeable batteries 20,21 and, more recently, served as a model dye in developing a new tooth whitening procedure. 22 However, except for several studies of 2 within layered inorganic materials, [23][24][25] surprisingly little attention has been devoted to its behavior under confinement, and in particular as a guest in supramolecular host-guest inclusion complexes. 26 Here, we investigated the complexation of indigo carmine within a metal-organic cage assembled from six cis-blocked Pd 2+ cations and four triimidazole panels (1 in Fig.…”