Compressional Behavior of Naphthalene (C₁₀H₈) and Anthracene (C₁₄H₁₀) up to 50 GPa

In this study, we explored the behavior of naphthalene and anthracene under compression to ∼50 and ∼42 GPa, respectively, using synchrotron single-crystal X-ray diffraction (SCXRD) in diamond anvil cells. Both compounds demonstrate remarkable structural stability, with no phase transitions being observed. The equations of states were obtained with the following parameters: V0 = 182.2(2) Å3, K0 = 8.4(10) GPa, and K′ = 5.5(6) for naphthalene, and V0 = 238.0(2) Å3, K0 = 8.4(5) GPa, and K′ = 8.0(4) for anthracene. Theoretical calculations correctly reproduce experimental data and enable accurate localization of hydrogen atoms. The analysis of Hirshfeld surfaces for both naphthalene and anthracene suggests that the herringbone packing motif of the molecules, the limited contribution of stronger C···C interactions to intermolecular bonding, and the high flexibility of relatively weak H···H interactions allow a gradual compaction of their structures without phase transitions. Our research contributes to the understanding of the compressional mechanisms, bonding evolution, and structural stability of polyaromatic hydrocarbons under compression.本研究借助金刚石压腔中的同步辐射单晶X射线衍射（synchrotron single-crystal X-ray diffraction，SCXRD）技术，分别探究了萘与蒽在被压缩至约50 GPa和约42 GPa时的压缩行为。两种化合物均展现出优异的结构稳定性，未观测到任何相变发生。我们获得了二者的状态方程参数：萘的状态方程参数为V0=182.2(2) ų、K0=8.4(10) GPa、K′=5.5(6)；蒽的状态方程参数为V0=238.0(2) ų、K0=8.4(5) GPa、K′=8.0(4)。理论计算可准确复现实验数据，并能精准定位氢原子位点。对萘与蒽的赫希菲尔德表面（Hirshfeld surfaces）分析表明，分子的人字形堆积基元、较强的C···C相互作用对分子间成键的有限贡献，以及相对较弱的H···H相互作用所具备的高柔性，使得二者的晶体结构可在不发生相变的前提下实现逐步压实。本研究有助于深化对多环芳烃（polyaromatic hydrocarbons）在压缩条件下的压缩机制、键合演化及结构稳定性的认知。