# Exploring the Structural Design, Antibacterial Activity, and Molecular Docking of Newly Synthesized Zn(II) Complexes with NNO-Donor Carbazate Ligands

## TL;DR

This paper describes the synthesis and antibacterial testing of new Zn(II) complexes with carbazate ligands, showing higher activity than the original ligands and potential for therapeutic use.

## Contribution

The novel Zn(II) complexes with NNO-donor ligands demonstrate enhanced antibacterial activity and promising molecular docking results against specific bacterial targets.

## Key findings

- The Zn(II) complexes exhibit higher antibacterial activity than their free ligands against periodontopathogen bacteria.
- Molecular docking suggests the complexes inhibit key proteins in S. mutans and P. gingivalis bacteria.
- Crystal structures reveal distorted square pyramid and octahedral geometries for the complexes.

## Abstract

The present work reports the synthesis and structural design of three novel Zn(II) complexes [Zn(L1)(CH3COO)(H2O)] (1), [Zn(L2)2] (2), and [Zn(L3)2] (3) with carbazate ligands, 2-acetylpyridine-methylcarbazate (HL1), 2-acetylpyridine-ethylcarbazate (HL2), and 2-acetylpyridine-benzylcarbazate (HL3). All compounds were characterized by spectroscopic methods, and the crystal structures of the complexes were elucidated by single-crystal X-ray. Based on the analysis, distorted square pyramid geometry is suggested for complex (1) and an octahedral geometry is suggested for complexes (2) and (3) with the ligands exhibiting an NNO-donor system. The 3D Hirshfeld surface and the 2D fingerprint plot were used to study the non-covalent interactions in the crystal structures. The in vitro antibacterial investigation of the free ligands and their complexes was performed against different strains of periodontopathogen bacteria. The Zn(II) complexes showed more potent antibacterial activity than the free ligand. Molecular docking studies showed the metal complexes as promising candidates for further therapeutic exploration, particularly in targeting the ATP-binding cassette transporter with peptidase domain of the cariogenic bacteria S. mutans (PDB code 5XE9) and the prolyl tripeptidyl aminopeptidase from P. gingivalis anaerobic bacteria (PDB code 2EEP) inhibition.