Organometallic β-turn mimetics. A structural and spectroscopic study of inter-strand hydrogen bonding in ferrocene and cobaltocenium conjugates of amino acids and dipeptides

Staveren, Dave R. van; Weyhermüller, Thomas; Metzler‐Nolte, Nils

doi:10.1039/b208363a

Cited by 106 publications

(148 citation statements)

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“…This lowfield chemical shift as well as the large temperature depen-dence ∆δ NH ϭ Ϫ12 ppb K Ϫ1 confirm that the NH proton is involved in a dynamic hydrogen bond in solution, which can arise from either intermolecular association or intramolecular folding processes. [13,18] The characteristic signal for the vibration of the acid carbonyl group appears at 1715 cm Ϫ1 in CH 2 Cl 2 and in THF, and is similar to that found for ferrocenedicarboxylic acid (1720 cm Ϫ1 in THF), and suggests the formation of carboxylic acid dimers. As both functional groups are involved in hydrogen bonding, a dynamic intermolecular aggregation in solution is proposed (Scheme 2).…”

mentioning

confidence: 54%

“…Thus, in the 1 H and 13 C NMR spectra signal sets for a C s -symmetric molecule are observed, e.g. only one 13 C resonance for the carbonyl carbon nuclei at δ ϭ 167.0 is seen (Table 3; in contrast to the two erroneous reported values of δ ϭ 165.1 and 167.0 [26] ). The IR absorption spectrum shows the signals assigned to the symmetric and asymmetric CO vibrations at 1778 cm Ϫ1 and 1717 cm…”

Section: Properties Of 4؊9mentioning

confidence: 67%

“…A weak temperature dependence is indicative of either a non-bonded hydrogen atom or a hydrogen atom involved in a locked hydrogen bond. [13,18] For 6, the weak temperature dependence of ∆δ NH ϭ Ϫ2.9 ppb K Ϫ1 is interpreted in terms of the ab- [a] Amide A ϭ ν NH,stretching .…”

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confidence: 99%

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Main Chain Ferrocenyl Amides from 1‐Aminoferrocene‐1′‐carboxylic Acid

2004

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The non‐natural amino acid 1‐aminoferrocene‐1′‐carboxylic acid is synthesised from ferrocene in eight steps. The folding and association phenomena of amido‐substituted ferrocenes in the crystal as well as in solution are studied by X‐ray crystallography, IR and NMR spectroscopy and DFT calculations. The amino acid is selectively protected at the amino group with the use of the fluorenyl‐9‐methoxycarbonyl (Fmoc) group. An amide‐linked ferrocene dimer is prepared using the HOBt/DCC protocol for amide formation. In the crystal the dimer forms a hydrogen‐bonded sheet structure, while in solution dynamic intramolecular hydrogen bonds are observed by VT 1H NMR and IR spectroscopy. The dynamic flipping process has been rationalised by DFT calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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confidence: 54%

Section: Properties Of 4؊9mentioning

confidence: 67%

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Main Chain Ferrocenyl Amides from 1‐Aminoferrocene‐1′‐carboxylic Acid

2004

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“…[22,23] The coupling constants for the protons on the substituted Cp rings were not resolved and thus, the signals appeared as broad singlets. The Cp resonances of the cobaltocenium complexes are shifted downfield significantly (d 5.2-6.4 ppm) compared with the spectra of the ferrocenoyl compounds (d 4.2-4.8 ppm).…”

Section: Resultsmentioning

confidence: 97%

Solid‐Phase Synthesis, Characterization, and Antibacterial Activities of Metallocene–Peptide Bioconjugates

et al. 2006

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This work shows how the introduction of an organometallic group enhances and modifies the specificity of biologically active peptides. Ferrocene was chosen as an organometallic group because it has been shown to alter the pharmacodynamic profile of bioactive compounds. A comparison with the isosteric cobaltocenium group allows one to explore the influence of charge and redox potential on the biological activity of the conjugates. Arginine and tryptophan containing peptides H-WRWRWR-NH(2) and H-RWRWRW-NH(2) and the metallocene peptide bioconjugates [M]-C(O)-RWRWR-NH(2) and [M]-C(O)-WRWRW-NH(2), where [M]=[Co(Cp)(C(5)H(4))](+), [Fe(Cp)(C(5)H(4))] were prepared by solid-phase peptide synthesis (SPPS). They were purified by HPLC, characterized by ESIMS and NMR spectroscopy, and tested for antibacterial properties against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the minimum inhibitory concentration (MIC) test. In most cases, no metal-specific activity could be observed. However, the conjugate [Fe(Cp)(C(5)H(4))-C(O)-WRWRW-NH(2)] 6 was found to be particularly effective against the Gram-positive S. aureus. The activity of this metallocene-pentapeptide conjugate (7.1 microM) was even better than the 20 amino acid naturally occurring pilosulin 2, which was used as a positive control. Unlike all other compounds tested, which were most active against the Gram-negative E. coli strain, the ferrocene conjugate 6 was the only compound in this series that was most active against Gram-positive bacteria. Given the health concerns resulting from multidrug resistant S. aureus strains, the incorporation of metallocenes may provide a novel line of attack.

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“…Ferrocene amides have been prepared by amide formation between amines and ferrocenecarboxylic acid derivatives. In these methods, ferrocene carboxylic acid was activated by transforming into; the acid chloride [16] succinimide [17], 1-hydroxybenzotriazole ester in the presence of dicylcohexylcarbodiimide (DCC) [17] or in situ activation of carboxylic acid by O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU) or O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluroniumtetrafluoroborate, (TBTU) [18]. Acid fluoride of ferrocene carboxylic acid was prepared for the derivatisation of ferrocenoyl group using cyanuric fluoride [19].…”

Section: Introductionmentioning

confidence: 99%

FT-IR, NMR spectroscopic and quantum mechanical investigations of two ferrocene derivatives

Alver¹,

Parlak²

2017

Bull. Chem. Soc. Eth.

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ABSTRACT. New ferrocene derivatives as N-(3-piperidin-1-ylpropyl)ferrocenamide and N-(pyridine-3-ylmethyl)ferrocenamide (Fc-3pica) and structural investigations were carried out with 1 H, 13 C, DEPT 45 or 135, HETCOR, COSY NMR and FT-IR spectroscopic techniques. Characterization of Fc-3ppa (FeC19H26N2O) and Fc-3pica (FeC17H16N2O) was also supported by density functional theory (DFT) used by B3LYP functional and 6-31G(d) or 6-311++G(d,p) basis sets. From the combination of all the results, it can be clearly seen that syntheses of Fc-3ppa and Fc-3pica have been successfully achieved. Theoretical values are successfully compared against experimental data and B3LYP method is able to provide satisfactory results for predicting NMR properties and vibrational frequencies of the synthesized ferrocene based systems.

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Organometallic β-turn mimetics. A structural and spectroscopic study of inter-strand hydrogen bonding in ferrocene and cobaltocenium conjugates of amino acids and dipeptides

Cited by 106 publications

References 29 publications

Main Chain Ferrocenyl Amides from 1‐Aminoferrocene‐1′‐carboxylic Acid

Main Chain Ferrocenyl Amides from 1‐Aminoferrocene‐1′‐carboxylic Acid

Solid‐Phase Synthesis, Characterization, and Antibacterial Activities of Metallocene–Peptide Bioconjugates

FT-IR, NMR spectroscopic and quantum mechanical investigations of two ferrocene derivatives

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