Hybrid systems based on organic dyes and clay minerals: Fundamentals and potential applications

Abstract

This review summarizes several aspects of the interactions between organic dyes and clay minerals, and presents some interesting properties of hybrid materials based on these components. It explains the basic phenomena and photophysical properties of dye/clay mineral hybrid systems (DCHS) while examining the role of clay minerals in them. A brief history of using dyes as tools for clay research and on traditional materials based on DCHS is presented. Metachromasy, the phenomenon of colour change related to the formation of dye molecular aggregates is described in detail and analysed from various perspectives. The properties of DCHS, including photoactivity, luminescence, photocatalytic properties, optical anisotropy and non-linear optical properties are analysed in detail. Clay minerals often play a significant role in the occurrence of specific photophysical phenomena such as resonance energy transfer and luminescence quenching and may influence various reactions, such as conformational changes in dye molecules, photochromism, photoisomerization, photosensitization and other photochemical processes. Routes to synthesize various types of hybrid materials are also described here. The relevance of DCHS for clay research, chemistry and materials science is summarized briefly.

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“…The idea is to transfer to modern materials the environmental resilience and other interesting properties of ancient materials, like Roman cements or the Blue Maya pigment, typically based on minerals. Indeed inclusion compounds of engineered clays are beginning to show actual potential as eco‐friendly functional materials . Such progress was also fostered by modeling studies – that suggested, for example, to contrast the worsening in the mechanical properties of a clay (caused by the incorporation of dyes) via the co‐adsorption of surfactants in the interlayer space of the clay .…”

“…Indeed inclusion compounds of engineered clays [47] are beginning to show actual potential as eco-friendly functional materials. [773][774][775][776][777][778] Such progress was also fostered by modeling studies -that suggested, for example, to contrast the worsening in the mechanical properties of a clay (caused by the incorporation of dyes) via the co-adsorption of surfactants in the interlayer space of the clay. [779][780][781] Taking inspiration from Blue Maya, the indigo molecule was recently encapsulated into zeolite L microcrystals yielding an exceptionally robust colorant: [782] the insight from simulations [191] was instrumental for the successful blockage of the crystal terminations.…”

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“…It has been shown that clay minerals play an important role in the occurrence of specific photophysical phenomena such as resonance energy transfer and luminescence quenching, and may influence various reactions, such as conformational changes in dye molecules, photochromism, photoisomerization, photosensitization and other photochemical processes (for review see Bujdak 2015).…”

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