Anthraphenylenes: Porous 2D Carbon Monolayers with Biphenyl-Anthracene Frameworks and Type-II Dirac line nodes

Carbon's versatility allows it to form diverse structures with unique properties, driven by its moderate electronegativity, small ionic radius, and ability to adopt \textit{sp}, \textit{sp\textsuperscript{2}}, and \textit{sp\textsuperscript{3}} hybridizations, individually or in combination. In this work, we introduce three novel 2D carbon allotropes -- $\alpha$, $\beta$, and $\gamma$-anthraphenylenes -- derived from biphenylene and Dewar-anthracene motifs, investigated through density functional theory calculations. Their thermodynamic and dynamic stability are confirmed by cohesive energy ($-7.02$ to $-7.26$ eV/atom), phonon dispersion, and \textit{ab initio} molecular dynamics simulations. The electronic structure analysis shows that all three anthraphenylenes display metallic behavior. All anthraphenylenes feature type-II Dirac Line Nodes (DLNs). Mechanical analysis highlights significant anisotropy, mainly in $\gamma$-anthraphenylene, which exhibits the highest rigidity. These monolayers feature a porous architecture with tunable mechanical properties, making them promising candidates for nanoelectronics and energy storage applications. By expanding the family of 2D carbon materials, anthraphenylenes provide new avenues for functional nanomaterial design.