A comprehensive overview of the orientation of tetradentate N2O2 donor Schiff base ligands in octahedral complexes of trivalent 3d metals

Karmakar, Mainak; Chattopadhyay, Shouvik

doi:10.1016/j.molstruc.2019.02.091

Cited by 35 publications

(17 citation statements)

References 194 publications

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“…Salen (S) is an excellent ligand that contains N 2 O 2 donor sites through which it readily binds to metal ions forming metal complexes with octahedral, tetrahedral, or square planar geometries [ 11 , 12 , 13 ]. The large numbers of studies on salen highlight its importance [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, DFT Calculations, Antiproliferative, Bactericidal Activity and Molecular Docking of Novel Mixed-Ligand Salen/8-Hydroxyquinoline Metal Complexes

et al. 2021

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Despite the common use of salens and hydroxyquinolines as therapeutic and bioactive agents, their metal complexes are still under development. Here, we report the synthesis of novel mixed-ligand metal complexes (MSQ) comprising salen (S), derived from (2,2′-{1,2-ethanediylbis[nitrilo(E) methylylidene]}diphenol, and 8-hydroxyquinoline (Q) with Co(II), Ni(II), Cd(II), Al(III), and La(III). The structures and properties of these MSQ metal complexes were investigated using molar conductivity, melting point, FTIR, 1H NMR, 13C NMR, UV–VIS, mass spectra, and thermal analysis. Quantum calculation, analytical, and experimental measurements seem to suggest the proposed structure of the compounds and its uncommon monobasic tridentate binding mode of salen via phenolic oxygen, azomethine group, and the NH group. The general molecular formula of MSQ metal complexes is [M(S)(Q)(H2O)] for M (II) = Co, Ni, and Cd or [M(S)(Q)(Cl)] and [M(S)(Q)(H2O)]Cl for M(III) = La and Al, respectively. Importantly, all prepared metal complexes were evaluated for their antimicrobial and anticancer activities. The metal complexes exhibited high cytotoxic potency against human breast cancer (MDA-MB231) and liver cancer (Hep-G2) cell lines. Among all MSQ metal complexes, CoSQ and LaSQ produced IC50 values (1.49 and 1.95 µM, respectively) that were comparable to that of cisplatin (1.55 µM) against Hep-G2 cells, whereas CdSQ and LaSQ had best potency against MDA-MB231 with IC50 values of 1.95 and 1.43 µM, respectively. Furthermore, the metal complexes exhibited significant antimicrobial activities against a wide spectrum of both Gram-positive and -negative bacterial and fungal strains. The antibacterial and antifungal efficacies for the MSQ metal complexes, the free S and Q ligands, and the standard drugs gentamycin and ketoconazole decreased in the order AlSQ > LaSQ > CdSQ > gentamycin > NiSQ > CoSQ > Q > S for antibacterial activity, and for antifungal activity followed the trend of LaSQ > AlSQ > CdSQ > ketoconazole > NiSQ > CoSQ > Q > S. Molecular docking studies were performed to investigate the binding of the synthesized compounds with breast cancer oxidoreductase (PDB ID: 3HB5). According to the data obtained, the most probable coordination geometry is octahedral for all the metal complexes. The molecular and electronic structures of the metal complexes were optimized theoretically, and their quantum chemical parameters were calculated. PXRD results for the Cd(II) and La(III) metal complexes indicated that they were crystalline in nature.

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Section: Introductionmentioning

confidence: 99%

Synthesis, DFT Calculations, Antiproliferative, Bactericidal Activity and Molecular Docking of Novel Mixed-Ligand Salen/8-Hydroxyquinoline Metal Complexes

et al. 2021

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“…They are characterized by an imine group (>C=N-), which exhibits strong bands in infrared spectroscopy [4]. Schiff bases that usually coordinate to a metal center through the imine nitrogen atom, have been widely used as ligands in coordination chemistry [5][6][7][8]. This is due to their facile synthesis, structural flexibility, easily tunable electronic properties, associated with their diverse applications in various branches of science [9].…”

Section: Introductionmentioning

confidence: 99%

Transition metal(II) complexes featuring push-pull dianionic Schiff base ligands: synthesis, crystal structure, electrochemical, and NLO studies

Celedón

Roisnel

Carrillo

et al. 2020

Journal of Coordination Chemistry

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The present study reports the synthesis and characterization of a family of three new neutral Zn(II), Cu(II), Co(II) bimetallic (2-4) and one ionic Co(II) trimetallic (5) complexes of ferrocene-containing unsymmetrically-substituted N 2 O 2 tetradentate Schiff base ligands. They were all prepared via a three-component one-pot template reaction involving the 4hydroxyphenyl substituted ferrocenyl-containing half unit Fc-C(=O)CH=C(4-C 6 H 4 OH)NH-CH 2 CH 2 NH 2 (Fc = ferrocenyl = (η 5 -C 5 H 5 )Fe(η 5 -C 5 H 4 )), metal(II) acetate and 5nitrosalicylaldehyde (for 2-4) or the organometallic salicylaldehyde [Cp*Ru(η 6 -2-OH-C 6 H 4 CHO)]PF 6 (for 5) (Cp* = η 5 -C 5 Me 5 ). The four complexes were isolated as air and moisture insensitive solids in yields > 80 %. They were characterized using several analytical techniques such as CHN analyses, ESI mass, FT-IR, UV-vis and NMR spectroscopy, including single crystal X-ray diffraction analysis. The crystal structure of 3 reveals that the four-coordinate copper atom adopts a square planar geometry with two nitrogen and two oxygen atoms as donors occupying cis positions. An electrochemical study utilizing cyclic voltammetry showed for each compound a reversible redox process ascribed to the Fe(II)/Fe(III) couple of the appended donor ferrocene. The largest anodic potentials were measured for the two Co(II) species. The second-order NLO responses of the push-pull chromophores 2-5 have been determined by harmonic light scattering measurements in N,Ndimethylformamide solutions at 1.91 μm incident wavelength, and rather high, non-resonant quadratic hyperpolarisability β values ranging from 140-280 x 10 -30 esu were determined.

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“…The complexes were obtained in moderate to very good yields, using reaction conditions that are similar to those reported in the literature for the synthesis of related Zn complexes . The Zn complexes obtained from the tetradentate ligands in Scheme can be categorized as salen‐like complexes (“Zn(salen)”) ( 27a‐Zn , 28a‐Zn , and 28e‐Zn ), while the Zn complexes derived from the bidentate ligands 26a – 26o (Scheme ) can be described as homoleptic bis(salicylaldiminato) complexes (“Zn(sal) 2 ”). During the synthesis of complex 26b‐Zn , it was noticed that the choice of base in the reaction had a large impact on the nature of the product (Scheme and Scheme ).…”

Section: Resultsmentioning

confidence: 77%

The Suzuki–Miyaura Cross‐Coupling as the Key Step in the Synthesis of 2‐Aminobiphenyls and 2,2'‐Diaminobiphenyls: Application in the Synthesis of Schiff Base Complexes of Zn

2020

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2‐Nitrophenylboronic acids serve as interesting starting materials for the construction of biphenyl‐ and terphenyl‐based amines if subjected to the Suzuki–Miyaura reaction. Unfortunately, these boronic acids suffer from low reactivity in Suzuki reactions, alongside their low stability in the presence of Pd. Herein, a general method for the construction of 2‐nitro‐substituted bi‐ and terphenyls is presented, with special emphasis on the synthesis of 2‐amino‐2'‐nitrobi‐ and terphenyls. Comparisons are made with other boronic acids that have some of the aforementioned issues. Finally, the application of the obtained 2‐amino‐2'‐nitrobi‐ and terphenyls as starting materials for the synthesis of bi‐ and terphenyl based di‐ and triamines is encountered for, with emphasis on the use of these amines as precursors for Schiff base ligands. In addition, the synthesis of some Zn complexes of these ligands is presented.

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A comprehensive overview of the orientation of tetradentate N2O2 donor Schiff base ligands in octahedral complexes of trivalent 3d metals

Cited by 35 publications

References 194 publications

Synthesis, DFT Calculations, Antiproliferative, Bactericidal Activity and Molecular Docking of Novel Mixed-Ligand Salen/8-Hydroxyquinoline Metal Complexes

Synthesis, DFT Calculations, Antiproliferative, Bactericidal Activity and Molecular Docking of Novel Mixed-Ligand Salen/8-Hydroxyquinoline Metal Complexes

Transition metal(II) complexes featuring push-pull dianionic Schiff base ligands: synthesis, crystal structure, electrochemical, and NLO studies

The Suzuki–Miyaura Cross‐Coupling as the Key Step in the Synthesis of 2‐Aminobiphenyls and 2,2'‐Diaminobiphenyls: Application in the Synthesis of Schiff Base Complexes of Zn

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