System of sequences in multivariate reticular structures

One of the most advanced and challenging topics in modern reticular chemistry is structure multivariation. This Perspective defines the fundamentals of multivariation by considering sequences of chemical species as its true essence, thereby addressing the classification of multivariate structures and presenting new concepts for their analysis and application. When variance is encountered in reticular structures such as metal-organic frameworks, it occurs as multiple kinds of functionalities bound and distributed in aperiodic lattices. In these multivariate systems, unknown spatial arrangements of functionalities create properties that go beyond those of their simple sum. It is therefore essential that we learn how to recognize, study and use these arrangements, and for this purpose we propose using the concept of sequences. Accordingly, we propose a classification system, outline a method for characterizing sequences and describe the application to self-propelled reticular machines. On a fundamental level, this contribution transforms the chemist's thinking from the usual 'make, characterize, use' protocol of doing chemistry to a discovery routine based on finding correlations between input synthesis parameters and output performance. This approach provides an alternative and widely accessible pathway for determining the properties that the system of sequences confers on multivariate reticular structures.