Abstract
<title>Abstract</title> <p>Porous crystalline organic materials have largely relied on macrocycles as topological rings to maintain porosity, which restricts the degree-of-freedom for structural dynamics and demands delicate synthetic control to avoid amorphous kinetic products. Here, we report rectilinear organic frameworks (ROFs) as a new class of crystalline porous materials composed of orderly packed linear polymer chains that can overcome the reliance on macrocycles. We synthesized twelve ROFs via linear polycondensation, nine of which resolved to atomic precision using electron diffraction. Their porosity emerges entirely from specific uniaxial or biaxial chain packing, governed by backbone stiffness and pendant groups that collaboratively frustrate dense packing. Linker elongation results in pore expansion, demonstrating modular material design and providing ROFs capable of gas separation. This macrocycle-free design enables efficient room-temperature scale-up, and structural transformations fundamentally unavailable to conventional frameworks. For a biaxial ROF, water adsorption triggers a coherent global rearrangement of chains, giving hydrogen-bonded water channels with high proton conductivity. Furthermore, we develop a crystal structure prediction method suitable for one-dimensional structures to analyze the energy landscape of ROFs and facilitating their rational design. Ultimately, ROFs establish a critical link between conventional linear polymers and reticular frameworks, providing a versatile platform for advanced porous materials.</p>