Nonplanar Nanographene\nwith a Large Conjugated π‑Surface

Conjugated π-surfaces are ubiquitous in molecules\nand materials.\nHowever, large π-surfaces up to a few nanometers in size are\ndifficult to construct in an atomically precise manner. They tend\nto aggregate because of strong π–π interactions,\nresulting in notorious problems for both purification and spectroscopic\ninvestigations. Here, by contrast, we report the design, synthesis,\nand full characterizations of a nonplanar nanographene <b>1</b>, which has a large, precise, and nonstacked π-surface. It\nis soluble in common organic solvents and allows for thorough investigations.\nThe structure of <b>1</b>, comprising 85 fused rings with an\nextended π-surface of 3 nm in size, is unambiguously confirmed\nby single-crystal X-ray diffraction. Unusual electronic structures,\nrecord-high near-infrared absorption, pronounced magnetic shielding,\nand ultrastrong heteromolecular van der Waals complexations are demonstrated,\nenabling us to establish a clear structure–property relationship,\nwhich has been elusive for decades. These results have broad implications\nfor studying and understanding various phenomena and processes relevant\nto both discrete and interacting π-surfaces.