Characterization and Structure–Property Relationships of Organic–Inorganic Hybrid Composites Based on Aluminum–Magnesium Hydroxycarbonate and Azo Chromophore

Abstract

In this study, novel organic–inorganic composites were prepared by the complexation of dicarboxylic azo dye (AD) with aluminum–magnesium hydroxycarbonate (AlMg–LH). This procedure provides an effective method for the stabilization of dicarboxylic organic chromophores on an AlMg−LH host. The structures of the hybrid composites were examined by X-ray diffraction (XRD), secondary ion mass spectrometry (TOF-SIMS), 27-Al solid-state nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA) and scanning transmission electron microscopy (STEM). The TOF-SIMS method was applied to investigate the metal–dye interactions and to monitor the thermal stability of the organic–inorganic complexes. Secondary ion mass spectrometry confirmed the presence of a characteristic peak for C18H10O5N2Mg22+, indicating that both carboxylic groups interacted with AlMg−LH by forming complexes with two Mg2+ ions. Modification with hybrid pigments affected the crystal structure of the AlMg−LH mineral, as shown by the appearance of new peaks on the X-ray diffraction patterns. Adsorption of the dicarboxylic chromophore not only led to significantly enhanced solvent resistance but also improved the thermal and photostability of the hybrid pigments. We propose a possible arrangement of the azo dye in the inorganic matrix, as well as the presumed mechanism of stabilization.

New Organic/Inorganic Pigments Based on Azo Dye and Aluminum-Magnesium Hydroxycarbonates with Various Mg/Al Ratios

“…Second, the interaction between the dye and the LH matrix contributed to the decrease in the concentration of CO 3 2− ions in the LH matrix, as was confirmed by TOF-SIMS. Therefore, the mechanism for the formation of the organic inorganic pigment with this chromophore is analogous to that proposed in our previous works (in which we used other azo and anthraquinone chromophores) [31,32], and is related mainly to interactions between acidic groups from the azo dye and the alkaline LH host (Figure 10).…”

“…In our previous work, we studied the effect of dye types and their functionalities on the properties of lake pigments. Azo and anthraquinone chromophores were precipitated mainly by aluminum-magnesium hydroxycarbonate with Mg/Al ratios of 30:70 [31,32]. However, the nature and morphology of the applied carrier may also affect the formation of organic/inorganic pigments.…”

Incorporation of Lutein on Layered Double Hydroxide for Improving the Environmental Stability

“…This demonstrated that lutein molecules did not completely embed into the interlayer of LDH because of the definite three-dimensional structure of lutein. Furthermore, it was clearly established that the strong affinity of CO 3 2− to metal ions of LDH resulted in the absence of anion exchange reactions between lutein and LDH [40][41][42]. However, no obvious changes were observed from non-basal (009), (110) and (113) reflection after incorporation of natural lutein molecules, indicating that the LDH crystals were preserved during the preparation of composites [43].…”

Improved Aging Stability of Ethylene-Norbornene Composites Filled with Lawsone-Based Hybrid Pigment

“…In the present study, lawsone was selected as an active organic compound and stabilized onto aluminum-magnesium hydroxycarbonate (LH) by the precipitation method. In our previous research, we had used this method to obtain hybrid pigments based on anthraquinone and azo chromophores [20,21]. The host-dye interactions and morphology of the hybrid LH/lawsone pigment were characterized by TOF-SIMS, 27 Al NMR spectroscopy, X-ray powder diffraction (XRD) and scanning electron microscopy (SEM).…”