Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. The ordered porous frameworks like MOFs and COFs are generally constructed using the monomers through distinctive metal-coordinated and covalent linkages. Meanwhile, the inter-structural transition between each class of these porous materials is an under-explored research area.
However, such altered frameworks are expected to have exciting features compared to their pristine versions. The structural phase transition offered in-situ pore size engineering from 1. The construction of a framework from another framework with new linkages opens interesting opportunities for phase-engineering. The structural phase transition of solids involves several physicochemical changes including lattice transformations of crystalline phases 1 , 2 , 3. The external triggers such as light, electricity, temperature, pressure, and chemical induction result in slight modification or full transformations of the structure of crystalline solids 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , Importantly, structural phase engineering is recognized and explored in extended molecular materials such as metalโorganic frameworks MOFs 15 , 16 , MOFs are crystalline porous solids, composed of organic linkers and metal knots linked through coordination bonds 18 , The fine regulation over the structure of MOFs through phase engineering opened the window of functionally diverse framework architectures Notably, phase engineering of MOFs alters or modifies their building blocks, lattices, porosity, etc.
Moreover, the investigations on phase-engineering of MOFs provide the opportunity for understanding the structureโproperty correlation of materials. However, the reported phase engineering of MOFs mostly dealt with the physical transformation of the crystalline phases. The primary coordination bonds between metal knots and organic linkers are preserved in every case of such transformations.
The replacement of coordinated metals in the framework into covalently bonded organic linkers has never been reported before. This type of phase engineering results in a complete transformation of MOFs into another class of porous materials, called covalent organic frameworks COFs 21 , 22 , 23 , 24 , 25 , 26 , the crystalline and porous organic solids linked by symmetric organic linkers.
The inter-class transformation of crystalline porous materials is a rarely explored research area and has the potential to provide more opportunities to understand the fine physicochemical tuning of the transformed material.
