An Asymmetric Phytochemical as a Building Block for Robust Structurally Resolved Crystalline Frameworks.

Plant polyphenols and related oxygen-donor phytochemicals are attractive natural ligands for metal-organic materials owing to their rich chemical reactivity, structural diversity, and sustainability. However, current phytochemical coordination chemistry remains dominated by amorphous systems, and structurally resolved crystalline frameworks are still largely restricted to simple and symmetric molecules. This gap has hindered atom-level understanding of phytochemical coordination and limited the rational development of crystalline materials from these abundant natural ligands. Here, we report SCU-1, the first structurally resolved crystalline coordination framework constructed from hematoxylin (HMT), a historically important but structurally complex and asymmetric phytochemical. Structural modeling, three-dimensional electron diffraction (3DED), Rietveld refinement, and quantum-chemical calculations together reveal that such an asymmetric phytochemical can assemble into periodic crystalline frameworks while generating coordination heterogeneity. Structural resolution further defines precise pore architectures, coordination environments, and host-guest interaction sites, thereby enabling direct elucidation of structure-property relationships. Importantly, SCU-1 exhibits exceptional robustness, strong CO2 affinity, and visible-light-driven photocatalytic CO2 conversion in water with selective ethanol production. These results establish asymmetric phytochemicals as viable building units for robust crystalline metal-organic materials and demonstrate the importance of structural determinacy in advancing phytochemical coordination chemistry and structure-property relationships.