In the traditional view, spin pairing occurs between two electrons in a chemical bond where the bonding interaction compensates for the penalty of electrostatic repulsion. It is a mystery whether spin pairing can occur between two non-bonded electrons within a molecular entity. Unveiling this type of spin entanglement (that is, pairing between two spatially segregated spins) at the molecular scale is a long-standing challenge. Clar’s goblet, proposed by Erich Clar in 1972, provides an ideal platform to verify this unusual property. Here we report the solution-phase synthesis of Clar’s goblet and experimental elucidation of its spin properties. Magnetic studies reveal that the two spins are spatially segregated with an average distance of 8.7 Å and antiferromagnetically coupled in the ground state with an ΔE_S–T of −0.29 kcal mol⁻¹. Our results provide insight into the spin entanglement in Clar’s goblet and may inspire the design of correlated molecular spins for quantum information technologies.

在传统观点中，自旋对发生在化学键中的两个电子之间，其中键合相互作用补偿了静电排斥的损失。分子实体内的两个非键合电子之间是否可以发生自旋配对是一个谜。在分子尺度上揭示这种类型的自旋纠缠（即两个空间分离的自旋之间的配对）是一项长期的挑战。Clar 的高脚杯由 Erich Clar 于 1972 年提出，为验证这一不寻常的特性提供了一个理想的平台。在这里，我们报道了 Clar 高脚杯的液相合成及其自旋性质的实验阐明。磁性研究表明，这两个自旋在空间上是分离的，平均距离为 8.7 Å，并且在基态下呈反铁磁耦合，ΔE_S–T 为 -0.29 kcal ^mol-1。我们的结果提供了对 Clar 高脚杯中自旋纠缠的见解，并可能激发量子信息技术相关分子自旋的设计。