Computational design of linear, flat, and tubular nanomolecules using planar tetracoordinate carbon C2Al4 units

C2Al4 (CH3)8 (1) contains two planar tetracoordinate carbons in its C2Al4 core. On the basis of the geometric characters of 1, we previously used it as building blocks to design molecular chains via face-to-face (FF) condensation. In this DFT study, we show the condensation can also take place vertex-to-vertex (VV). The various VV condensations of 1 units can result in new families of molecular structures including one-dimensional molecular chains, two-dimensional sheets, and molecular tubes. They were all characterised to be energy minima by frequency calculations at the B3LYP/6-31G* level. Their HOMO–LUMO gaps larger than 3.6 eV indicate the stability of their electronic structures. Furthermore, the condensations do not destroy the C2Al4 ptC core, as the geometric and electronic structures of the C2Al4 cores in these molecules are similar to those of C2Al4 core in the C2Al4(CH3)8 building block.