The Cu-P bond lengths show less variation, ranging from 2.1943 to 2.2119Å (average 2.2023±0.0023Å). Interestingly, these measurements indicate that the bond lengths between the Cu11 and Cu18 NCs do not undergo significant changes despite the structural modifications within the core and motifs. Finally, the overall cluster size of the Cu18 NC does not increase substantially, which can be attributed to the motif units adopting a zigzag pattern. This configuration effectively accommodates the expanded Cu9 core, thus optimizing the spatial arrangement of the cluster. This detailed arrangement demonstrates the nuanced interplay between core expansion and motif adaptation, which together contribute to the stability and functionality of the Cu18PTT NC.