Synthesis, Characterization and Crystal Structures of Schiff Base Copper Complexes with Urease Inhibitory Activity.

Shuang Han,Yuan Wang

doi:10.17344/acsi.2021.6965

Abstract

Urease inhibitors can inhibit the decomposition rate of urea, and decrease the air pollution caused by ammonia. In this paper, four new copper(II) complexes [CuL(ONO2)]n (1), [Cu2L2(μ1,3-N3)2] (2), [CuBrL] (3), and [CuClL] (4), where L = 5-bromo-2-(((2-methylamino)ethyl)imino)methyl)phenolate, have been synthesized and characterized. The complexes were characterized by elemental analyses, IR and UV-Vis spectroscopy, molar conductivity, and single crystal X-ray diffraction. X-ray analysis reveals that Cu atoms in complexes 1 and 2 are in square pyramidal coordination, and those in complexes 3 and 4 are in square planar coordination. The molecules of the complexes are linked through hydrogen bonds and π···π interactions. The inhibitory effects of the complexes on Jack bean urease were studied, which showed that the complexes have effective activity on urease.

Highlights

Too rapid increase of soil pH upon urea hydrolysis catalyzed by urease activity causes the loss of urea nitrogen as gaseous ammonia, which is toxic to plants and contributes to the production of fine inorganic particulate matter.[4]
Schiff bases are a kind of interesting ligands in the formation of metal complexes, which have received particular attention due to their facile synthesis, versatile structures, and good biological activities.[10]
The Schiff base ligand was prepared by reaction of 4-bromosalicylaldehyde and N-methylethane-1,2-diamine in methanol

Summary

Introduction

Urea is a major nitrogen-containing soil fertilizer, with an annual production projected to reach 226 million tons in 2021.1 Once deposited in soil, urea quickly hydrolyzes by urease to yield NH3.2 This reaction causes a number of agronomic, environmental and economic problems and affects the global nitrogen cycle.[3]. Too rapid increase of soil pH upon urea hydrolysis catalyzed by urease activity causes the loss of urea nitrogen as gaseous ammonia, which is toxic to plants and contributes to the production of fine inorganic particulate matter.[4]. This process causes tropospheric pollution by NO, NO2 and N2O, which is a greenhouse gas with 300 times the heat trapping capacity of CO2.5 Urease occurs widely in most bacteria, plants, algae, fungi and invertebrates.[6]. Urease enzyme catalyzes the decomposition of urea into ammonia in high efficiency, with the rate 1014 times faster than the non-catalyzed reaction.[7] This process is harmful for the health of human beings and environment.

1. General Methods and Materials

Synthesis of Complex 4

Cu1–N1 Cu1–Cl1 O1–Cu1–N2 O1–Cu1–Cl1 N2–Cu1–Cl1

Results and Discussion

Conclusion