Cages meet gels: Smart materials with dual porosity

Soft materials have found uses in many areas, such as medicine, robotics, and battery research. These advances are the result of the properties of gels stemming from both their solid-like and their liquid-like features. However, fine-tuning of these properties and an onset of new applications can be envisaged if gels are coupled to metal-organic cages, discrete three-dimensional structures containing well-defined cavities. In this perspective, we review the types of cage-gel smart materials synthesized to date, their properties, and their potential applications, such as in molecular separation, catalysis, and luminescent materials. Finally, we highlight current challenges and opportunities for future research.