Abstract : Using density functional theory (DFT) with dispersion correction and ab initio post Hartree-Fock
methods, we treat the bonding, the structure, the stability and the spectroscopy of the complexes between
Znq+ and imidazole (Im), Znq+Imn (where q = 0, 1, and 2; n = 1-4). These entities are subunits of zeolitic
imidazolate frameworks (ZIFs) and Zn-enzymes, which possess relevant roles in industrial and biological
domains, respectively. We also investigate the Imn (n = 2-4) clusters for comparison. For each species, we
determine several new structures that were not found previously. Our calculations show a competition
between atomic metal solvation, either by s-type interactions or p-stacking type interaction, and
hydrogen bonding (H-bonding). This results in several geometrical environments around the metal. These
are connected with structural properties and the functional role of Zn cation within ZIFs and Zn-enzymes.
Moreover, we show that the Zn2+Imn subunits do not absorb in the Vis domain, which may be related to
the photostability of ZIFs. Our findings are important for the development of new applications of ZIFs
and metalloenzymes.
