Synthesis, Spectral Characterization, and In Vitro Cytotoxicity of Some Fe(III) Complexes Bearing Unsymmetrical Salen-Type Ligands Derived from 2-Hydroxynaphthaldehyde and Substituted Salicylaldehydes

Quang Trung Nguyen,Phuong Nam Pham Thi,Nguyen Van Tuyen,Damião Pergentino De Sousa

doi:10.1155/2021/8028064

Quang Trung Nguyen, Phuong Nam Pham Thi + Show 2 more

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https://doi.org/10.1155/2021/8028064

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Abstract

Six Fe(III) complexes bearing unsymmetrical salen-type ligands derived from 2-hydroxynaphthaldehyde and substituted salicylaldehydes were synthesized by coordinating the unsymmetrical salen-type ligands with FeCl3.6H2O. The synthetic complexes were characterized by electrospray ionization mass spectra (ESI-MS), effective magnetic moments (μeff), and infrared (IR) and ultraviolet-visible (UV-Vis) spectra. The spectroscopic data are in good agreement with the suggested molecular formulae of the complexes. Their cyclic voltammetric studies in acetonitrile solutions showed that the Fe(III)/Fe(II) reduction processes are electrochemically irreversible. The in vitro cytotoxicity of the obtained complexes was screened on human cancer cell lines KB (a subline of Hela tumor cell line) and HepG2 (a human liver cancer cell line) and a normal human cell line HEK-293 (Human Embryonic Kidney cell line). The results showed that the synthetic Fe(III) complexes are highly cytotoxic and quite selective. The synthetic complexes bearing unsymmetrical salen-type ligands with different substituted groups in the salicyl ring indicate different cytotoxicity.

Highlights

Schiff bases with donors (N, O, etc.) have been widely investigated due to their diverse pharmacological applications [16], in which tetradentate Schiff bases are derived from salicylaldehydes and diamines, which form the Schiff bases known as “salen” with an N2O2 donor group being able to coordinate with different metal ions [17]. ese diamine Schiff bases with OH groups in ortho positions are of interest because of the presence of tautomerism between keto-amine and enolimine forms [18]. e transition metal complexes of tetradentate Schiff bases have received much attention about their structure, magnetic and electrochemical characterization, and their potential application in biological functions lately
Many symmetrical tetradentate Schiff bases and their transition metal complexes have been extensively studied on the preparation, spectral characterization, and biological activity [21,22,23]; recently, unsymmetrical tetradentate Schiff base ligands and their complexes have been paid attention [24,25,26]
It should be realized that the coordinated ligands around central metal ions in natural systems are unsymmetrical. erefore, in this work, we continue with the synthesis, spectral characterization, and in vitro anticancer behavior of Fe(III) complexes Journal of Chemistry bearing unsymmetrical salen-type Schiff bases derived from 2-hydroxynaphthaldehyde and substituted salicylaldehydes

Summary

Introduction

(Z)-1-(((2-((E)-(2-Hydroxy-5-methoxybenzylidene) amino) phenyl) amino) methylene) naphthalen-2 (1H)-one (H2L6): yellow powder, 92%; HP-TOF-MS (m/z): 397.1546 [M + H]+ (Cal. 397.4459); IR (KBr, cm−1): 2925 (], C-H), 2610 (], O-H), 1615 (], C N), 1575 (], C C), 1486, 1316 and 1273 (], C-N), 1207, 1156 (], C-O); 1040, 834, 748 (δ, C-H), 472; 1H-NMR (DMSO-d6, 500 MHz, δ (ppm), J (Hz)): δ 15.81 (d, J 9.0, 1H, NH), 10.81 (s, 1H, OH), 9.56 (d, J 9.0, 1H, HC−N), 9.03 (s, 1H, HC N), 8.43 (d, J 8.0, 1H, Naph), 8.07 (d, J 7.5, 1H, Naph), 7.82 (d, J 9.0, 2H, 1H-Naph, 1H-Sal), 7.70 (d, J 7.0, 1H, Ph), 7.51–7.41 (m, 3H, 2HNaph, 1H-Ph), 7.35 (t, J 7.0, 1H, Ph), 7.29 (t, 1H, Ph), 7.03 (dd, J 9.0, 3.5, 1H, Sal), 6.92 (d, J 9.0, 1H, Sal), 6.80 (d, J 9.0, 1H, Naph), 3.88 (s, 3H, OCH3); 13C-NMR (DMSOd6, 125 MHz, δ (ppm)): δ 176.65 (1C, C O), 159.67 (1C, C N), 153.51 (1C, C-O), 152.24 (1C, C-OCH3), 150.57 (1C, HC−NH), 140.81 (1C, N−CAr), 138.06 (1C, HN−CAr), 135.91 (1C, Naph), 133.72 (1C, Naph), 128.96 (1C, Naph), 128.11 (1C, Naph), 127.59 (1C, Sal), 126.63 (1C, Naph), 126.06 (1C, Naph), 124.44 (1C, Naph), 123.26 (1C, Ph), 121.48 (1C, Sal), 120.95 (1C, Ph), 119.94 (1C, Ph), 118.65 (1C, Naph), 117.65 (1C, Naph), 117.51 (1C, Sal), 112.34 (1C, Sal), 108.20 (1C, Ph), 55.58 (1C, OCH3; UV-Vis (MeOH, 3 × 10−5 M, λ/nm, ε/cm−1 M−1): 234 (44,000), 263 (22,667), 320 (16,667), 350 (16,667), 450 (13,667), 474 (12,667). Unsymmetrical salen-type Schiff base complexes were prepared from the obtained ligands and FeCl3.6H2O in 1 : 1 molecular ratio following the published procedure [28,29,30].

Results

Conclusion