Simultaneous presence of mono- and bi-cationic bipyridyls within a metal-organic supramolecular host: crystal structure, spectral and Hirshfeld surface analysis

A new supramolecular metal-organic complex, {[Fe(CN)₆]^3-(H₂bipy)²⁺(Hbipy)⁺·3H₂O} (where bipy ipywhere biolecular metal-organic complex, {[Fe(CN)ccepted: 30 October 2022rized by single crystal X-ray crystallographic study (SC-XRD), powder X-ray diffraction (PXRD) and other spectroscopic analysis. Structural analysis reveals that the complex crystallizes in monoclinic space group P2₁/c and is a 3 D supramolecular complex. Cyanide-water hydrogen bonding interactions between {Fe(CN)₆}^3- and guest water molecules form a wave-like 2 D supramolecular layer structure parallel to the crystallographic ac-plane with the formation of rectangular cavities of dimension 10.6 × 9.8 Å. These 2 D layers are further connected by O3W-H2W3···O1W hydrogen bonding interactions to form a 3 D supramolecular structure with the creation of 1 D supramolecular channels along the crystallographic a-axis. The bi-cationic (H₂bipy)²⁺ form two different N⁺-H···water hydrogen bonding interactions (N8⁺-H8···O2W and N7⁺-H7···O3W) with two different water molecules and reside within the rectangular cavities. Monocationic (Hbipy)⁺ moieties form a 1 D supramolecular chain structure through repetitive N···H-N⁺ hydrogen bonding interactions and are present within the 1 D supramolecular channels. In addition, these two different types of bipy moieties are interconnected to each other through π···π interactions. Hirshfeld surface analysis and the corresponding 2 D fingerprint plots clearly identify the presence of different types of supramolecular interactions between the two differently charged bipyridyl moieties and the host framework, and N-H/H-N contacts, corresponding to the hydrogen bonding interactions, have a significant contribution to the total surface. Both the absorption and emission spectra of the complex have also been studied.