Many heterogeneous and flat two dimensional (2D) materials with finite band gap have been researched for its suitability in exotic applications. For instance, zinc oxide (ZnO) with honey comb structure has optimum band gap that makes it eligible for opto-electronic applications. Recently, our research group have found that pyrene based tetratopic ligands (PTL) are suitable for functionalizing ZnO nanorods. In this study, neat and defective 2D ZnO layer is functionalized with different pyrene based ligands with various functional groups. First principles calculations are done and the degree of affinity of pyrene ligands towards neat and defective ZnO sheets is compared.