As drug carriers, calixarenes are often investigated and employed in numerous sectors as host molecules. The use of calixarenes in drug delivery systems is a relatively new notion, despite the fact that countless studies have been conducted on calixarenes and their various applications. It is worthwhile to research the computational investigation of the host-guest interaction between calixarenes and para-aminobenzoic acid (PABA) in terms of their binding energy and band gap. The first principles study of PABA sensing by calix [4] arene (C4) and calix [6] arene (C6) based on density functional theory (DFT) was carried out in this study using Quantum ESPRESSO software. By using the computational method, the binding energy, as well as the band gap of C4, C6, PABA, and the novel complexes, C4-PABA, and C6-PABA, were calculated. Different interaction distances were used in the formation of complexes. Our results demonstrate the reduction of the band gap for both complexes. Furthermore, the calculated binding energy shows the promising stability of the complexes. This demonstrates the sensing ability of calixarenes towards PABA and the potential anti-cancer properties of calixarene-PABA in sunscreens.
