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Lee et al. Microstructures 2023;3:2023021 https://dx.doi.org/10.20517/microstructures.2023.08 Page 5 of 19

Figure 1. (A) Illustration of the zeolite-Y incorporating one (CdS) unit in each sodalite cage and (B) the zeolite-Y incorporating a larger
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CdS QD in each supercage. Reprinted with permission [46] . Copyright © 2007 American Chemical Society.

and improved stability in water compared with unprotected CsPbBr QDs, due to uniform distribution and
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interconnection of QDs within supercage of zeolite X structure . This work suggests that counter cations
[54]
of zeolite structures are important to improve stability and sensitivity while also forming more direct
interaction with guest material to create new types of QDs. The discovery of this interaction opens a whole
set of new research directions for the selection of QDs and cations of zeolite structure.

QUANTUM DOTS IN COVALENT ORGANIC FRAMEWORKS
Compared to zeolites, COFs are porous materials formed through chemical bonds between organic-organic
moieties. These building blocks consist of organic molecules that are covalently linked to form a porous
crystalline structure. The resulting chemical bonds between organic building blocks create a flexible and
tunable framework structure that enables precise control over the size, shape, and chemical properties of the
pores and channels within the material. This flexibility and tunability make COFs highly versatile and
suitable for a wide range of applications, such as gas storage, separation, catalysis, and sensing. Additionally,
zeolites are composed of rigid inorganic frameworks, which limits their flexibility and tunability, though
they are still widely used in applications such as catalysis and adsorption.

Considering the dynamic interaction observed between zeolites and QDs, it is anticipated that COFs, in
addition to their inherent structure, can provide further tunability to improve the performance of the
resulting composites. The dynamic nature of COFs presents both opportunities and challenges for the
generation of QDs within their pores. Obtaining a well-ordered three-dimensional crystalline COF structure
and preserving its integrity during QD synthesis are among the most critical challenges that need to be
overcome in the development of QD-COF composites. COFs can form two- or three-dimensional
structures through covalent bonds between organic monomers composed of light elements such as C, H, N,
B, and O [55,56] . In natural systems, covalent and noncovalent interactions play crucial roles in the formation