(10−13) Despite all of the properties that MOFs possess, these materials are usually obtained as powders and this form limits their applications. (9) Applying MOFs for filtration of toxic gases and for air purification has become a hot research topic because of the increasing global air pollution.

(4) Tunable pore properties, various active sites, and thermal stability offer MOF materials’ potential applications for gas storage and separation, (5,6) catalysis, (7,8) and drug delivery systems.

(1−3) Their large and accessible surface area up to 7000 m 2 g –1 is one of the most important characteristics. Because of their well-defined structure and functionality, these porous materials have received a great research attention over the recent years.

Metal–organic frameworks (MOFs) are a class of crystalline porous materials made by linking metal ions and organic ligands. This work demonstrated the firm attachment of MOF-5 crystals onto the substrate, facilitating various potential applications. It was found that the dopamine-modified cotton increased the strength of MOF-5 crystals attached to fibers. To determine how firmly crystals were attached to the cotton fibers, the substrates were exposed to a constant and strong air flow. The crystalline structure of MOF-5 was confirmed using X-ray diffraction. The effects of dopamine modification on the crystal growth and the formation of “necklace” morphology were investigated using scanning electron microscopy analysis. Unlike paper, the cotton bulb had a looser structure and MOF-5 crystals grew around the fibers, forming a stable “necklace” morphology. In the case of paper, which had a structure with fibers closely packed to each other, MOF-5 crystals grew only on the surface of fibers (one side) and could easily fall off. Besides dopamine, the structure of the substrate also played a major role in the crystal growth. The formed polydopamine film promoted the growth of MOF-5 crystals, which were bonded to the substrates. Dopamine was used as a surface modification agent to improve the compatibility between MOF-5 crystals and the used substrates.

Herein, metal–organic framework (MOF)-5 crystals were grown on cellulose-based substrates including paper and cotton.

A Suitable Necklace by Kim Akhtar