Pseudomorphic Replacement in the Transformation between Metal–Organic Frameworks toward Three-Dimensional Hierarchical Nanostructures

The
construction of three-dimensional hierarchical materials from
nano building blocks has received tremendous attention because of
the intriguing architecture and promising application potential of
these materials. However, the use of traditional assembly methods
to construct hierarchical nanostructures with complicated 3D shapes
across multiple length scales remains challenging. Herein, we developed
a new strategy to fabricate hierarchical nanostructures by borrowing
the concept of pseudomorphic replacement from mineralogy; this concept
refers to a specific conversion between minerals with the preservation
of the pristine shape through an interface-coupled dissolution–precipitation
mechanism. By employing pseudomorphic replacement to the transformation
between metal–organic frameworks (MOFs), a series of hierarchical
MOF materials with similar nanostructures but various shapes and dimensions
were successfully fabricated. The experiments verified that these
transformations not only preserve the shape of the pristine MOF crystals
but also proceed via an interface-coupled dissolution–recrystallization
process. To our knowledge, our investigation is the first explicit
demonstration of pseudomorphic replacement in the transformation between
MOFs, offering a new route to hierarchical materials with enhanced
control ability and extended control scope.