Framework materials such as covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) are often viewed as the predictable products of reticular design, in which rigid building blocks assemble into a single, ideal net. Yet their formation is shaped by a competition between covalent or coordinative bond formation and weaker interactions such as sterics, geometry, and intermolecular forces. Rather than treating this competition as an obstacle, we deliberately design organic linkers at the edge of predictable assembly, where it gives rise to polymorphism, structural complexity, superstructures, correlated disorder, and heterogeneous pore environments that uniform, well-behaved systems cannot offer. This linker-centric approach links molecular-level synthetic design to the assembly processes that govern advanced framework materials and points to new opportunities in selective adsorption, catalysis, and transport.

In this talk, I will discuss how five-fold symmetric linkers introduce geometric frustration into MOFs and COFs, how amphiphile phase separation shapes the pore interior of COFs, and how steric interactions steer topology and polymorph formation.