A Combined Theoretical Calculation and Hirshfeld Surface Analysis of Cooperative Non-covalent Interactions in the Crystal Packing in [Cu(L1)2(EDA)]

The monomeric complex [Cu(L1)(2)(EDA)] (I) [L1 = 2,4-dinitrobenzoic acid, EDA = ethylenediamine), was solved in orthorhombic space group (Pbca) and characterized by elemental analysis, IR spectroscopy, powder XRD analysis, and single-crystal X-ray crystallography, in addition to photoluminescence and thermal stability investigation. The Cu2+ ion is connecting with two L1 through monodentate mode of coordination and two nitrogen atoms from EDA. I is associated through cooperative non-covalent interactions, which are also responsible for the strengthening of the molecular assembly and organize it into a supramolecular 2D motif. Hirshfeld surface analysis was also applied to investigate the cooperative non-covalent supramolecular interactions and the results were compared with the single-crystal X-ray diffraction data. To get clear insights into the both species, electronic properties such as HOMO-LUMO, electronic chemical potential and other derived parameters were also highlighted using DFT calculations at M06-2X/ 6-31G** level of theory. The observed photoluminescence of complex I arises mainly from an excited LLCT state with small MLCT contributions (from Cu2+ to the unoccupied p orbital of L1). The presented work exhibits another example of the utility and prosperity of such kinds of subtle information and features especially, and for complex I at molecular level, generally.