A Convenient Synthetic Route for the Preparation of Nonsymmetric Metallo‐salphen Complexes

Kleij, Arjan W.; Tooke, Duncan M.; Spek, Anthony L.; Reek, Joost N. H.

doi:10.1002/ejic.200500628

Cited by 73 publications

(42 citation statements)

References 59 publications

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“…-{[(3-aminopyridin-4-yl)imino]-methyl}-4,6-di-tertbutyl-phenol (L2) was previously reported by Kleij et al,21 by condensation of 3,4diaminopyridine with 3,4-di-tert-butyl-2-hydroxi-benzaldehyde, and was obtained in 80% yield.The FT-IR spectra of compounds L1 and L2 exhibited several bands between 2500 and 4000 cm -1 . The main absorption frequencies showed strong symmetric and asymmetric bands due to O-H vibrations at 3469 cm -1 , and two bands at 3264 and 3136 cm -1 assigned to -NH 2 for L1, and an O-H vibration at 3478 cm -1 , and two bands at 3330 and 33205 cm -1 assigned to -NH 2 for L2.…”

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confidence: 85%

“…21,22 The reaction was stirred for 24 h at room temperature and then filtered, and the precipitate was washed with methanol and diethyl ether. 21,22 The reaction was stirred for 24 h at room temperature and then filtered, and the precipitate was washed with methanol and diethyl ether.…”

Section: Synthesis Of (E)-2-{[(2-aminopyridin-3-yl)imino]-methyl}-46mentioning

confidence: 99%

“…were described by Kleij et al 21,22 In this work, a complete study of their electronic properties to understand the role of the hydrogen bond on its biological activities and molecular properties was performed. 5 2.…”

Section: Introductionmentioning

confidence: 99%

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Spectral, theoretical characterization and antifungal properties of two phenol derivative Schiff bases with an intramolecular hydrogen bond

et al. 2015

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Schiff bases show a wide variety of applications of great importance in medicinal researchdue to their range of biological activities. In this article we describe the electronic structure, optical, redox and antifungal properties of (E)-2-{[(2-aminopyridin-3-yl)imino]-methyl}-4,6-ditert-butyl-phenol (L1) and (E)-2-{[(3-aminopyridin-4-yl)imino]-methyl}-4,6-di-tert-butyl-phenol (L2), two isomers phenol derivatives Schiff bases exhibiting a strong intramolecular hydrogen bond (O-H•••N). These compounds were characterized by their 1 H, HHCOSY, 13 C-NMR, FT-IR spectra, and by cyclic voltammetry. All the experimental results were complemented with theoretical calculations using density functional theory (DFT) and time-dependent DFT (TDDFT). The antimicrobial activity of the compounds described herein was assessed by determining the minimal inhibitory concentration (MIC) and by a modification of the Kirby-Bauer method. We tested Salmonella enterica serovar Typhi (S. Typhi, Gram-negative bacteria), Cryptococcus spp. (yeast), and Candida albicans (yeast). We found that neither L1 nor L2 showed antimicrobial activity against S. Typhi or Candida albicans. On another hand, L2, in contrast to L1, exhibited antifungal activity against a clinical strain of Cryptococcus spp.(MIC: 4.468 µg/mL) even better than ketoconazole antifungal medicaments. We mentioned above that L1 and L2 are isomer species, because the amino groups is in ortho-position in L1 and in para-position in L2, however no significant differences were detectable by UV-vis, FT-IR, oxidation potentials and TDDFT calculations, but importantly, the antifungal activity clearly discriminated between these two isomers.LUMO) and 74% (HOMO-3 → LUMO) for L1 and 74% (HOMO-4 →LUMO) and 26% (HOMO-2 →LUMO) for L2 in all the solvents and in gas phase. The bands assigned like π→π* transitions involve the HOMO→ LUMO for L1 and L2. The comparison between the solvent spectra with the gas phase showed no significant shift in the UV-vis spectra when the solvent polarity changes. Figure 3. Calculated UV-vis absorption spectra for (E)-2-{[(2-aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butyl-phenol (L1) in different implicit solvents and gas phase.

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Section: Synthesis Of (E)-2-{[(2-aminopyridin-3-yl)imino]-methyl}-46mentioning

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Spectral, theoretical characterization and antifungal properties of two phenol derivative Schiff bases with an intramolecular hydrogen bond

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“…A similar protocol was utilized to obtain some double salen and nonsymmetric salen complexes. [31,32] Scheme 3. …”

Section: Synthesis Of Ligandsmentioning

confidence: 99%

Electronic Spectra of Mono‐ and Dinuclear Complexes of Fully π‐Conjugated salphen Ligands Synthesized by Using 2,6‐Dihydroxynaphthalene Carbaldehydes

2009

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A series of mono-and dinuclear zinc(II), copper(II), nickel(II), and iron(III) complexes of novel salphen ligands were synthesized and spectroscopically characterized. The mononuclear ligand (H 2 L 1 ) was synthesized from 2,6-dihydroxynaphthalene-1-carbaldehyde and an o-phenylenediamine; the dinuclear ligand (H 4 L 2 ), which was not isolated, contains a 2,6-dihydroxynaphthalene-1,5-dicarbaldimine linkage that enables extended π-conjugation over two salphen units. By means of a controlled sequence of condensation reactions, the constituents were built into either mono-(

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“…[31] The mono-imine was used by the authors as a potentially tridentate ligand for Al III Kleij et al have used this mono-imine synthon to prepare, in a one-pot procedure, nonsymmetrical salphen [salphen = N,NЈ-1,2-phenylene-bis(salicylideneimine)] complexes using a templating approach with metal ions (Scheme 14). [32] The procedure proved to be useful for both systems having the asymmetry within the bridging unit (including salpyr compounds) [33] as well as for nonsymmetrical salen derivatives with two distinct phenyl side groups (Scheme 14). In general, the mono-imine reactant 22 is treated with a mixture of another salicylaldehyde and a metal salt to afford exclusively the nonsymmetrical salen complexes 23 (Scheme 14) in high isolated yield.…”

Section: Nonsymmetrical Salen Derivatives Via Monoimine Precursorsmentioning

confidence: 99%

Nonsymmetrical Salen Ligands and Their Complexes: Synthesis and Applications

Kleij

2008

Eur J Inorg Chem

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151

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The importance of salen ligands in homogeneous catalysis and material chemistry has unambiguously been demonstrated over the last two decades. In the majority of the existing studies, C2‐symmetrical salen complexes have been used as catalysts for many organic conversions; however, the amount of structures that can become available for catalyst fine‐tuning by changing the peripheral groups on the bridging unit and the aryl side groups is limited. In order to widen their scope in catalytic procedures new designs of salen structures have been probed, and above all unsymmetrical versions. In this respect, it has become increasingly important to develop reliable and efficient preparative methods for these nonsymmetrical salen compounds, and more particularly ligands with two differently substituted salicylideneimine groups. The presence of a single functional group suitable for connection to various supports has great advantages, since full access of the catalytic sites in the supported structure may be preserved and new and/or improved catalytic properties can be tailored. On the other hand, different functions on both sides of the central N2O2 unit can be used to force the formation of specific (supramolecular) architectures. This review discloses the general methods available for the preparation of unsymmetrical salen ligands/complexes and the most important fields of their application. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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A Convenient Synthetic Route for the Preparation of Nonsymmetric Metallo‐salphen Complexes

Cited by 73 publications

References 59 publications

Spectral, theoretical characterization and antifungal properties of two phenol derivative Schiff bases with an intramolecular hydrogen bond

Spectral, theoretical characterization and antifungal properties of two phenol derivative Schiff bases with an intramolecular hydrogen bond

Electronic Spectra of Mono‐ and Dinuclear Complexes of Fully π‐Conjugated salphen Ligands Synthesized by Using 2,6‐Dihydroxynaphthalene Carbaldehydes

Nonsymmetrical Salen Ligands and Their Complexes: Synthesis and Applications

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