To investigate the empty metallacages, Each cage is shown with its respective metal centres (Pt, Ni, Cu, Au) coordinated by four ligands (L), forming highly symmetrical, elongated structures. These metallacages are investigated for their potential to encapsulate cisplatin molecules, with their geometry playing a critical role in determining the feasibility and efficiency of encapsulation. The internal volume of each metallacage was calculated by measuring the distances between metal centres on the top and bottom and the distances between carbon atoms at the equatorial centre (Supplementary 6.2, Figure ). These volume calculations, presented in the table 3, are essential for understanding the structural characteristics of the metallacages. The size of the internal cavity significantly influences encapsulation efficiency; larger volumes can lead to weaker interactions between the cage (host) and the encapsulated cisplatin (guest), potentially causing premature drug release. Therefore, optimising cage volume is crucial to ensure that cisplatin remains securely encapsulated until it reaches its intended target, thereby enhancing the effectiveness of the drug delivery system. Each cage is shown with its respective metal centres (Pt, Ni, Cu, Au) coordinated by four ligands (L), forming highly symmetrical, elongated structures. These cages exhibit a high degree of symmetry and are characterized by elongated, cylindrical shapes, which are relevant for their potential application in encapsulating cisplatin molecules. Also, while geometry optimisation has not been completed for endo-n Cu 2 L 4 because of small energy fluctuation, its distorted shape has been shown in the figure . Endo-n cages in figure demonstrated similar outputs with endo-c cages in figure . Shortly, 376 Cu 2 L 4 lost sharp symmetry, while the other provided promising structures. To deeply investigate 377 cages, their features, including inside volume, have been provided in table 4 using the approach 378 described in section 6.3 and Figure . The table details the primary diagonal distances D1 (in red) and D2 (in green) in Ångströms ( Å) within different metallacages encapsulating cisplatin. Additionally, it provides the calculated average volumes in cubic Ångströms ( Å3 ), along with the percentage change in volume (∆volume) relative to the reference Pd 2 L 4 cage. The atomic radii of the metals in picometers (pm) are also listed, reflecting their influence on the overall geometry and stability of the cages. Note that the Cu 2 L 4 cage failed to converge in the calculations, indicating issues with its structural stability.