Editorial

3 pages, 192 KiB

Open AccessEditorial

Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery

by Lubov V. Snegur

Inorganics 2023, 11(2), 75; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics11020075 - 03 Feb 2023

Cited by 1 | Viewed by 942

Ferrocene is already 70 years old! A respectable age, as claimed by the authors of this Special Issue [...] Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

Research

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21 pages, 6779 KiB

Open AccessArticle

Biological Evaluation and Conformational Preferences of Ferrocene Dipeptides with Hydrophobic Amino Acids

by Monika Kovačević, Mojca Čakić Semenčić, Ivan Kodrin, Sunčica Roca, Jana Perica, Jasna Mrvčić, Damir Stanzer, Krešimir Molčanov, Valentina Milašinović, Lidija Brkljačić and Lidija Barišić

Inorganics 2023, 11(1), 29; https://doi.org/10.3390/inorganics11010029 - 03 Jan 2023

Cited by 3 | Viewed by 1561

Abstract

Despite the large number of peptidomimetics with incorporated heteroannularly functionalized ferrocenes, few studies have investigated their bioactivity. Here, we report the biological evaluation and conformational analysis of enantiomeric dipeptides derived from 1′-aminoferrocene-1-carboxylic acid (Fca) and hydrophobic amino acids (AA = Val, Leu, Phe). [...] Read more.

Despite the large number of peptidomimetics with incorporated heteroannularly functionalized ferrocenes, few studies have investigated their bioactivity. Here, we report the biological evaluation and conformational analysis of enantiomeric dipeptides derived from 1′-aminoferrocene-1-carboxylic acid (Fca) and hydrophobic amino acids (AA = Val, Leu, Phe). The conformational properties of Y-AA-Fca-OMe (Y = Ac, Boc) were elucidated by experimental (IR, NMR, CD, and X-ray) and theoretical (DFT) methods. The prepared dipeptides were screened for their antimicrobial activity against selected Gram-positive and Gram-negative bacteria, lactic acid bacteria and yeasts, while their antioxidant activity was tested by DPPH and FRAP methods. Of all compounds tested, dipeptide d-2a showed the best antibacterial properties against S. aureus, B. subtilis, and P. aeruginosa at a concentration of 2 mM. The time–kill curves showed that antibacterial activity was concentration- and time-dependent. Chirality (d-) and a more polar-protecting group (Ac) were found to affect the biological activity, both antimicrobial and antioxidant. All investigated peptides are considered to be highly hydrophobic and chemically stable in both acidic and buffer media. Dipeptides d-1a–3a, which showed biological activity, were subjected to the determination of proteolytic activity, revealing very good resistance to proteolysis in the presence of chymotrypsin. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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29 pages, 2490 KiB

Open AccessArticle

Convenient Access to Ferrocene Fused aza-Heterocycles via the Intramolecular Ritter Reaction: Synthesis of Novel Racemic Planar-Chiral 3,4-Dihydroferroceno[c]pyridines and 1H-Ferroceno[c]pyrroles

by Yuliya S. Rozhkova, Irina V. Plekhanova, Alexey A. Gorbunov and Yurii V. Shklyaev

Inorganics 2022, 10(11), 214; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics10110214 - 19 Nov 2022

Cited by 1 | Viewed by 1448

Abstract

An efficient and easy approach to the synthesis of novel racemic planar-chiral 3,4-dihydroferroceno[c]pyridines and 1H-ferroceno[c]pyrroles via the intramolecular Ritter reaction of 2-ferrocenyl-3,3-dimethylbutan-2-ol with nitriles and thiocyanates in the presence of MeSO₃H was developed. Aromatic and [...] Read more.

An efficient and easy approach to the synthesis of novel racemic planar-chiral 3,4-dihydroferroceno[c]pyridines and 1H-ferroceno[c]pyrroles via the intramolecular Ritter reaction of 2-ferrocenyl-3,3-dimethylbutan-2-ol with nitriles and thiocyanates in the presence of MeSO₃H was developed. Aromatic and aliphatic nitriles, phenylacetonitriles, and β-oxonitriles produced exclusively 3,4-dihydroferroceno[c]pyridines. The condensation of 2-ferrocenyl-3,3-dimethylbutan-2-ol with various thiocyanates, including alkyl thiocyanates, benzyl thiocyanate, and ethyl 2-thiocyanatoacetate, yielded not only 3,4-dihydroferroceno[c]pyridines but also 1H-ferroceno[c]pyrroles. The selectivity of these reactions depended on the temperature and the order of addition. The size of substituents at the α-position to the sulfur atom of thiocyanates also had a significant effect on the distribution of products. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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16 pages, 2651 KiB

Open AccessArticle

Synthesis of Novel Ferrocene-Benzofuran Hybrids via Palladium- and Copper-Catalyzed Reactions

by Enikő Nagy, Márk Váradi, Zoltán Nagymihály, László Kollár, Krisztina Kovács, Kitti Andreidesz, Ágnes Gömöry, Nikolay Tumanov, Johan Wouters and Rita Skoda-Földes

Inorganics 2022, 10(11), 205; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics10110205 - 11 Nov 2022

Cited by 1 | Viewed by 1474

Abstract

The combination of the ferrocene skeleton with pharmacophores often leads to molecules with interesting biological properties. Five ferrocene-benzofuran hybrids of different structures were synthesized by transition metal catalyzed reactions. The efficiency of both homogeneous and heterogeneous catalytic methods was tested. The products were [...] Read more.

The combination of the ferrocene skeleton with pharmacophores often leads to molecules with interesting biological properties. Five ferrocene-benzofuran hybrids of different structures were synthesized by transition metal catalyzed reactions. The efficiency of both homogeneous and heterogeneous catalytic methods was tested. The products were characterized using ¹H, ¹³C NMR and FTIR spectroscopy, HRMS and cyclic voltammetry. The structure of one of the new compounds was also proved with X-ray crystallography. The new hybrids showed moderate cytotoxicity on MCF-7 and MDA-MB-231 cell lines. It is remarkable that the less curable MDA-MB-231 cell line was more sensitive to treatment with three ferrocene derivatives. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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16 pages, 3807 KiB

Open AccessArticle

New Ferrocene-Based Metalloligand with Two Triazole Carboxamide Pendant Arms and Its Iron(II) Complex: Synthesis, Crystal Structure, ⁵⁷Fe Mössbauer Spectroscopy, Magnetic Properties and Theoretical Calculations

by Peter Antal, Ivan Nemec, Jiří Pechoušek and Radovan Herchel

Inorganics 2022, 10(11), 199; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics10110199 - 07 Nov 2022

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Abstract

The new ferrocene-based metalloligand bis (N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl])ferrocene carboxamide (L) was prepared through derivatization of 1,1′-ferrocenedicarboxylic acid with 4-amino-3,5-di(pyridyl)-4H-1,2,4-triazole. The composition and purity of L in the solid state was determined with elemental analysis, FT-IR spectroscopy, and its crystal [...] Read more.

The new ferrocene-based metalloligand bis (N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl])ferrocene carboxamide (L) was prepared through derivatization of 1,1′-ferrocenedicarboxylic acid with 4-amino-3,5-di(pyridyl)-4H-1,2,4-triazole. The composition and purity of L in the solid state was determined with elemental analysis, FT-IR spectroscopy, and its crystal structure with single-crystal X-ray analysis, which revealed that the substituted cyclopentadienyl rings adopt the antiperiplanar conformation and the crystal structure of L is stabilized by O–H···N and N–H···O hydrogen bonds. The molecular properties of L in solution were investigated with NMR and UV-VIS spectroscopies, and cyclic voltammetry disclosed irreversible redox behavior providing one oxidation peak at E_1/2 = 1.133 V vs. SHE. Furthermore, the polymeric Fe^II complex {Fe(L)(C(CN)₃)₂}_n (1) was prepared and characterized with elemental analysis, FT-IR spectroscopy, ⁵⁷Fe Mössbauer spectroscopy, and magnetic measurements. The last two methods confirmed that a mixture of low- and high-spin species is present in 1; however, the spin crossover properties were absent. The presented study was also supported by theoretical calculations at the DFT/TD-DFT level of theory using TPSS and TPSSh functionals. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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20 pages, 8884 KiB

Open AccessArticle

Ferrocenylmethylphosphanes and the Alpha Process for Methoxycarbonylation: The Original Story

by Kevin M. Fortune, Christa Castel, Craig M. Robertson, Peter N. Horton, Mark E. Light, Simon J. Coles, Mark Waugh, William Clegg, Ross W. Harrington and Ian R. Butler

Inorganics 2021, 9(7), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics9070057 - 17 Jul 2021

Cited by 2 | Viewed by 3462

Abstract

The Lucite Alpha process is the predominant technology for the preparation of acrylics. This two-stage process involves the palladium-catalysed formation of methyl propanoate from ethene, CO, and methanol, followed by the oxidative formylation of methyl propanoate into methyl methacrylate. A range of bis [...] Read more.

The Lucite Alpha process is the predominant technology for the preparation of acrylics. This two-stage process involves the palladium-catalysed formation of methyl propanoate from ethene, CO, and methanol, followed by the oxidative formylation of methyl propanoate into methyl methacrylate. A range of bis-1,2-disubstituted aminomethylferrocenes has been prepared and characterised. These complexes serve as precursors to a variety of bulky ferrocenylmethyldiphosphanes that, in turn, function as ligands in the palladium-catalysed process. We describe the crystal structures of five ligand precursors and provide a rationale for their design. In situ catalyst testing on palladium complexes derived from ferrocenylphosphanes demonstrates that these are highly selective (>99.5%) catalysts for the formation of methyl propanoate from ethene, CO, and methanol and have turnover numbers exceeding 50,000. This article credits those researchers who worked on this project in the early days, who received little or no credit for their achievements and endeavours. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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Review

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20 pages, 3441 KiB

Open AccessReview

Modern Trends in Bio-Organometallic Ferrocene Chemistry

by Lubov V. Snegur

Inorganics 2022, 10(12), 226; https://doi.org/10.3390/inorganics10120226 - 26 Nov 2022

Cited by 13 | Viewed by 2431

Abstract

Organometallic sandwich compounds, especially ferrocenes, possess a wide variety of pharmacological activities and therefore are attracting more and more attention from chemists, biologists, biochemists, etc. Excellent reviews concerning biological aspects and design of ferrocene-modified compounds appear regularly in scientific journals. This brief overview [...] Read more.

Organometallic sandwich compounds, especially ferrocenes, possess a wide variety of pharmacological activities and therefore are attracting more and more attention from chemists, biologists, biochemists, etc. Excellent reviews concerning biological aspects and design of ferrocene-modified compounds appear regularly in scientific journals. This brief overview highlights recent achievements in the field of bio-organometallic ferrocene chemistry from 2017 to 2022. During this period, new ferrocene-modified analogues of various bio-structures were synthesized, namely, betulin, artemisinin, steroids, and alkaloids. In addition, studies of the biological potential of ferrocenes have been expanded. Since ferrocene is 70 years old this year, a brief historical background is also given. It seemed to me useful to sketch the ‘ferrocene picture’ in broad strokes. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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32 pages, 13065 KiB

Open AccessReview

Advanced Application of Planar Chiral Heterocyclic Ferrocenes

by Alexandra A. Musikhina, Polina O. Serebrennikova, Olga N. Zabelina, Irina A. Utepova and Oleg N. Chupakhin

Inorganics 2022, 10(10), 152; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics10100152 - 23 Sep 2022

Cited by 3 | Viewed by 1594

Abstract

This manuscript is reviewing the superior catalytic activity and selectivity of ferrocene ligands in a wide range of reactions: reduction of ketones, hydrogenation of olefins, hydroboration, cycloaddition, enantioselective synthesis of biaryls, Tsuji–Trost allylation. Moreover, the correlation between a ligand structure and its catalytic [...] Read more.

This manuscript is reviewing the superior catalytic activity and selectivity of ferrocene ligands in a wide range of reactions: reduction of ketones, hydrogenation of olefins, hydroboration, cycloaddition, enantioselective synthesis of biaryls, Tsuji–Trost allylation. Moreover, the correlation between a ligand structure and its catalytic activity is discussed in this review. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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23 pages, 13852 KiB

Open AccessReview

Ferrocenyl Migrations and Molecular Rearrangements: The Significance of Electronic Charge Delocalization

by Michael J. McGlinchey

Inorganics 2020, 8(12), 68; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics8120068 - 11 Dec 2020

Cited by 4 | Viewed by 2839

Abstract

The enhanced stabilization of a carbocationic site adjacent to a ferrocenyl moiety was recognized within a few years of the discovery of sandwich compounds. While a detailed understanding of the phenomenon was the subject of some early debate, researchers soon took advantage of [...] Read more.

The enhanced stabilization of a carbocationic site adjacent to a ferrocenyl moiety was recognized within a few years of the discovery of sandwich compounds. While a detailed understanding of the phenomenon was the subject of some early debate, researchers soon took advantage of it to control the ease and direction of a wide range of molecular rearrangements. We, here, discuss the progress in this area from the pioneering studies of the 1960s, to more recent applications in chromatography and analytical detection techniques, and currently in the realm of bioactive organometallic complexes. Several classic reactions involving ferrocenyl migrations, such as the pinacol, Wolff, Beckmann, and Curtius, are discussed, as well as the influence of the ferrocenyl substituent on the mechanisms of the Nazarov, Meyer-Schuster, benzoin, and Stevens rearrangements. The preparation and isomerizations of ferrocenyl-stabilized vinyl cations and vinylcyclopropenes, together with the specific cyclization of acetylcyclopentadienyl-metal derivatives to form 1,3,5-substituted benzenes, demonstrate the versatility and generality of this approach. Full article

(This article belongs to the Special Issue Ferrocene and Its Derivatives: Celebrating the 70th Anniversary of Its Discovery)

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