Interpreting the different emissive properties of cyclic triimidazole-based CuI and AgI coordination polymers: a QTAIM and IQA study

A QTAIM and IQA investigation on model compounds of two isostructural AgI and CuI coordination polymers (CPs) based on cyclic triimidazole (L), i.e. the [MIL]n 1D double-stranded stair chain and the [MClL]n 3D network (M = Cu, Ag), has allowed light to be shed on the different emissive behaviour associated with the two metal ions. According to a previously reported investigation [Malpicci et al. (2021). Inorg. Chem. Front. 8, 1312 – 1323], AgI CPs showed both fluorescence and multiple ligand-centred room-temperature phosphorescences, whereas CuI CPs displayed non-thermally equilibrated halogen and metal-to-ligand charge transfer and two ligand-centred phosphorescences, the latter observed only by their selective activation. Analysis of both local and integral QTAIM descriptors, including delocalization indices and source function, of the Ag — N and Cu — N bonds reveals a higher covalent and local character for the latter, explaining the greater metal – ligand electronic communication observed for the Cu compounds. Moreover, IQA investigation shows that the Cu — N bond is characterized by higher interaction energy, due to both higher electrostatic and exchange-correlation contributions. Analysis on the M — X (M = Ag, Cu; X = I, Cl) bonds, also present in these structures, highlights a much higher covalent and local character with respect to the M — N bonds.

Source: Acta Crystallographica Section B - November 9, 2021 Category: Chemistry Authors: Forni, A. Cariati, E. Carlucci, L. Lucenti, E. Marinotto, D. Pieraccini, S. Sironi, M. Tags: AgI and CuI coordination polymers room-temperature phosphorescence metal – ligand interaction QTAIM IQA source function halogen bond quantum crystallography research papers Source Type: research