Topological properties of metal-organic frameworks

Metal-organic frameworks (MOFs) are porous materials formed by strong bonds between metal ions and organic ligands to represent very high surface area, large pore volume, excellent chemical stability and unique morphology. Work on synthesis, structures and characteristics of many MOFs shows the importance of these frameworks with versatile applications, such as energy storage devices of excellent electrode materials, gas storage, heterogeneous catalysis, environmental hazard, assessment of chemicals and sensing of different gases. A topological property or index is a numerical invariant that predicts the physicochemical properties of the chemical compounds of the underlying molecular graph or framework. Wiener (1947) created the practice of the topological indices (TI's) in organic molecules with the reference of boiling point of paraffin. In this paper, we study the two different metalorganic frameworks with respect to the number of increasing layers with metal and organic ligands as well. We also compute the generalized Zagreb index and generalized Zagreb connection index of these frameworks. Moreover, the various indices and connection indices are obtained by using the aforesaid generalized versions. At the end, a comparison is also included between the indices and connection indices with the help of numerical values and their 3D plots.