Synthesis, characterization, crystal structure and bioactivity properties of the benzimidazole-functionalized PEPPSI type of Pd(II)NHC complexes

Abstract

Herein, six new benzimidazole-functionalized Pd-based complexes bearing N-propylphthalimide group were synthesized. These new PEPPSI type of Pd(II)NHC complexes (PEPPSI: Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) were prepared from the N-propylphthalimide substituted benzimidazolium salts, palladium chloride (PdCl2) and 3-chloropyridine. The structures of all (NHC)PdX2(3-chloropyridine) complexes have been clearly characterized by using NMR (1H and 13C), FTIR spectroscopic method, and elemental analysis techniques. Also, the structures of three of the (NHC)PdX2(3-chloropyridine) complexes were confirmed by single-crystal X-ray diffraction. Also, novel N-propylphthalimide-substituted (NHC)PdX2(3-chloropyridine) complexes effectively inhibited acetylcholinesterase (AChE), with Ki values in the range of 0.54 ± 0.10 to 3.01 ± 0.63 µM. For butyrylcholinesterase (BChE) was obtained with Ki values in the range of 0.82 ± 0.11 to 5.03 ± 0.86 µM. For α-glycosidase (α-Gly) the most effective Ki values of 1c, 1d, and 1b were with Ki values of 23.83 ± 5.98, 26.04 ± 7.11, and 30.61 ± 3.85 µM, respectively. All novel N-propylphthalimide-substituted PEPPSI complexes and control compounds had almost similar inhibition profiles.