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Hydrophilic polydentate Schiff-base ligands (available in the form of their disodium salts) which can selectively complex the uranyl(VI) cation and retain it in the aqueous phase; these ligands are not complexed to the same extent with trivalent Ln ions.
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Even 155 years after their first synthesis, Schiff bases continue to surprise inorganic chemists. Schiff-base ligands have played a major role in the development of modern coordination chemistry because of their relevance to a number of interdisciplinary research fields. The chemistry, properties and applications of transition metal and lanthanoid...
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Context 1
... ability of tetra-and pentadentate Schiff-base ligands to accommodate the steric demands of trans-{U VI O2} 2+ has led to intense interest in their application as extractants for this cation. In an excellent, relatively recent study, Hawkins' group evaluated the water-soluble tetradentate N,N′-bis-(5-sulfonatosalicylidene)-ethylenediamine (H2salen-SO3 2− , Figure 8) and pentadentate N,N′-bis-(5-sulfonatosalicylidene)-diethylenetriamine (H2saldiene-SO3 2− , Figure 8) Schiff bases for their ability to form complexes with UO2 2+ and Ln(III) ions in aqueous solution [7,56]. U(VI) could be selectively complexed and retained in the aqueous phase, whereas the representative trivalent lanthanide Eu(III) was extracted by bis(2-ethylhexyl)phosphoric acid in toluene. ...
Context 2
... ability of tetra-and pentadentate Schiff-base ligands to accommodate the steric demands of trans-{U VI O2} 2+ has led to intense interest in their application as extractants for this cation. In an excellent, relatively recent study, Hawkins' group evaluated the water-soluble tetradentate N,N′-bis-(5-sulfonatosalicylidene)-ethylenediamine (H2salen-SO3 2− , Figure 8) and pentadentate N,N′-bis-(5-sulfonatosalicylidene)-diethylenetriamine (H2saldiene-SO3 2− , Figure 8) Schiff bases for their ability to form complexes with UO2 2+ and Ln(III) ions in aqueous solution [7,56]. U(VI) could be selectively complexed and retained in the aqueous phase, whereas the representative trivalent lanthanide Eu(III) was extracted by bis(2-ethylhexyl)phosphoric acid in toluene. ...
Citations
... Schiff bases are a class of nitrogenous organic compounds that have a general structure R-CH=N-R', where R and R' can be an alkyl or aryl group, linear or cyclic, which can be substituted in many ways [1][2][3] They can be considered a subclass of imines, being secondary ketamines (when both R and R' are different from H) and secondary aldimines (when R or R' is an H atom), depending on the presented structure [1,2,4,5]. In the literature, they are considered synonyms for imines (>C=N-) and azomethines (or secondary aldimines, -HC=N-), as they are also known [1,[4][5][6][7][8]. They received this name because of Hugo Schiff , an Italian-German chemist laureated with the Nobel Prize and brother of the physiologist Moritz Schiff [1,2,4]. ...
... They received this name because of Hugo Schiff , an Italian-German chemist laureated with the Nobel Prize and brother of the physiologist Moritz Schiff [1,2,4]. Hugo Schiff also discovered other imines, in addition to studying aldehydes, which led to the development of the Schiff reagent, for the identification of these compounds, which consists of a colorless solution containing an indicator produced by the reaction between pararosaniline with sulfite in an acid medium [5,6]. ...
... Schiff's bases attract a lot of attention in the chemical area, mainly in inorganic chemistry, because of their ability to coordinate with almost all existing metal ions [9] and, therefore, expand the range of application of these compounds in all areas of research and development. They are considered "privileged ligands" [6,10], and are classic ligands for metal ions in p, d, and f blocks, having contributed a lot to coordination chemistry, especially in catalysis (homogeneous and heterogeneous catalysis) [2,7]. They are considered easy to form complexes with metals, in addition to being stable [6,[10][11][12]. ...
Schiff bases represent a valuable class of organic compounds, synthesized via condensation of primary amines with ketones or aldehydes. They are renowned for possessing innumerable applications in agricultural chemistry, organic synthesis, chemical and biological sensing, coating, polymer and resin industries, catalysis, coordination chemistry, and drug designing. Schiff bases contain imine or azomethine (-C=N-) functional groups which are important pharmacophores for the design and synthesis of lead bioactive compounds. In medicinal chemistry, Schiff bases have attracted immense attention due to their diverse biological activities. This review aims to encompass the recent developments on the antimicrobial activities of Schiff bases. The article summarizes the antibacterial, antifungal, antiviral, antimalarial, and antileishmanial activities of Schiff bases reported since 2011.
... Even 160 years after their first synthesis by the Italian-German Hugo Schiff , these azomethine (HC=N-) or imine (>C=N-) groups-containing molecules continue to surprise inorganic chemists because of their close relevance to a number of interdisciplinary research fields. [23][24][25] Because of their logical modular synthesis that allows strict control over the nature of donor atoms, denticity, chelating and/or bridging function, as well as their adjustable electronic and steric features, polydentate Schiff bases have played a great role in the development of coordination chemistry after the second world war, 26 being also important for the preparation of heterometallic complexes. [23][24][25][26] In a broader sense, formation of azomethines/imines is one of the types of reactions which define Dynamic Covalent Chemistry (DCC), an approach which is used in the synthesis of complicated molecules and extended structures because of the inherent "proof-reading" and "error-checking" associated with these reversible processes. ...
... [23][24][25] Because of their logical modular synthesis that allows strict control over the nature of donor atoms, denticity, chelating and/or bridging function, as well as their adjustable electronic and steric features, polydentate Schiff bases have played a great role in the development of coordination chemistry after the second world war, 26 being also important for the preparation of heterometallic complexes. [23][24][25][26] In a broader sense, formation of azomethines/imines is one of the types of reactions which define Dynamic Covalent Chemistry (DCC), an approach which is used in the synthesis of complicated molecules and extended structures because of the inherent "proof-reading" and "error-checking" associated with these reversible processes. 27,28 An interesting group of the family of tetradentate Schiff-base ligands consists of molecules derived from the condensation of salicylaldehyde (or its derivatives) with 2-aminobenzoic acid (or its derivatives). ...
The use of N-(2-carboxyphenyl)salicylideneimine (saphHCOOH) and N-(4-chloro-carboxyphenyl)salicylideneimine (4ClsaphHCOOH) for the synthesis of hexanuclear {ZnII4MIII2} (M = Cr, Fe) complexes is described. [Zn4Fe2(saphCOO)6(NO3)2(EtOH)2] (1), [Zn4Cr2(saphCOO)6(NO3)2(H2O)2] (2) and [Zn4Fe2(4ClsaphCOO)6(NO3)2(EtOH)2] (3), as 4CH2Cl2.2EtOH...
... As stated by two of the seven papers [1,2] published in the Special Issue entitled 'Oligonuclear Metal Complexes with Schiff Base Ligands' that I guest edited, the chemistry of Schiff bases began in 1864 due to the discovery made by Hugo Schiff [3], but even more than one and a half centuries after their first synthesis, Schiff bases continue to surprise inorganic chemists. ...
... The first review of the Special Issue by Demetrios I. Tzimopoulos, Malgorzata Holynska, Spyros P. Perlepes and co-workers entitled 'Oligonuclear Actinoid Complexes with Schiff Bases as Ligands-Older Achievements and Recent Progress' deals with the coordination chemistry of Schiff bases with actinoid (5f elements) ions [2]. This is an emerging area in recent years, compared to the more mature chemistry of transition metals and lanthanides. ...
As stated by two of the seven papers [...]
... Salines have an acidic and tetradentate 2N, 2O) structure [16]. The application areas of metal complexes synthesized from salen compounds are quite wide. ...
Compound that is a novel tetradentate Schiff base ligand [(3,4-bis(((E)-4-(diethylamino)-2-hydroxybenzylidene)amino)phenyl)(phenyl) methanone] (1), 4-(diethylamino) It was synthesized by the reaction of (3,4-diaminophenyl)(phenyl)methanone with -2-hydroxybenzaldehyde. Complex reactions with Co(II) (1a), Cu(II) (1b) and Ni(II) (1c) metals were prepared based on the obtained Schiff base ligand. The synthesized Schiff base and its Ni(II), Cu(II) and Co(II) complexes were featured using FT-IR, UV-vis, photoluminescence, mass and 1H and 13C-NMR spectroscopy. The characterization processes show that the tetradentate Schiff base compound coordinates with metal ions, oxygen of the hydroxyl group and nitrogen of the azomethine group.
... Schiff-base ligands have gained substantial attraction owing to their excellent tunability, structural flexibility, and selectivity toward central metal atom. 1,2 Schiff-bases are considered as privileged ancillary ligands because of their exceptional chelating capabilities toward transition metal ions to form varied geometries. 3,4 In particular, Schiff-bases with O-, S-, and N-bearing heterocyclic frameworks and their metal complexes in medicinal chemistry field have shown enhanced biological activity because of their similarity with natural products. ...
Herein, Cu (II), Zn (II), and Cd (II) complexes, [DEP(M)X2], encompassing the pyridine‐derived Schiff‐base ligand DEP, where DEP is (E)‐N,N‐diethyl‐2‐([pyridine‐2‐ylmethylene]amino)ethane‐1‐amine, are synthesized. X‐ray diffraction studies reveal distorted square pyramidal geometries for the Cd (II) and Cu (II) complexes, whereas the geometry of [DEP (Zn)Cl2] can best be described as trigonal bipyramidal. The antibacterial potential of DEP and its [DEP(M)X2] complexes were evaluated against four bacterial strains: Salmonella typhi, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa; five fungal strains: Candida glabrata, Candida albicans, Microsporum canis, Fusarium solani, and Aspergillus flavus; and Leishmania major protozoan. Complexes exhibited superior bactericidal, fungicidal, and leishmanicidal inhibition potential against all tested microbes compared with the free ligand. The preliminary cytotoxic activity of [DEP(M)X2] complexes on breast and colon carcinoma cells, that is, MCF‐7cell line and HCT‐116 cell line, respectively, revealed that studied complexes showed high cytotoxicity compared with ligand (DEP). Among the studied complexes, [DEP (Cd)Br2] exhibited an excellent inhibitory profile, as confirmed by the docking study. The molecular docking studies showed a good correlation between the biological activities of synthesized metal complexes and docking studies. We have confidence in the contribution of these complexes toward the design of new metal‐derived candidates that can treat infectious diseases.
... Thus, apologies are due to the researchers whose excellent work will not be mentioned here. This review is a consequence of our research efforts in the chemistry of actinoids [18][19][20][21][22], with emphasis on the use of oxime-and AO-based ligands [23][24][25]; the latter area contains a plethora of unpublished work from our group, which will be briefly described. ...
... The description of the inorganic chemistry of U is outside the scope of this review. The interested reader can find information in standard inorganic chemistry textbooks and in our recent review [18]. ...
Resource shortage is a major problem in our world. Nuclear energy is a green energy and because of this and its high energy density, it has been attracting more and more attention during the last few decades. Uranium is a valuable nuclear fuel used in the majority of nuclear power plants. More than one thousand times more uranium exists in the oceans, at very low concentrations, than is present in terrestrial ores. As the demand for nuclear power generation increases year-on-year, access to this reserve is of paramount importance for energy security. Water-insoluble polymeric materials functionalized with the amidoxime group are a technically feasible platform for extracting uranium, in the form of {UO2}2+, from seawater, which also contains various concentrations of other competing metal ions, including vanadium (V). An in-depth understanding of the coordination modes and binding strength of the amidoxime group with uranyl and other competing ions is a key parameter for improving extraction efficiency and selectivity. Very limited information on the complexation of {UO2}2+ with amidoximes was available before 2012. However, significant advances have been made during the last decade. This report reviews the solid-state coordination chemistry of the amidoxime group (alone or within ligands with other potential donor sites) with the uranyl ion, while sporadic attention on solution and theoretical studies is also given. Comparative studies with vanadium complexation are also briefly described. Eight different coordination modes of the neutral and singly deprotonated amidoxime groups have been identified in the structures of the uranyl complexes. Particular emphasis is given to describing the reactivity of the open-chain glutardiamidoxime, closed-ring glutarimidedioxime and closed-ring glutarimidoxioxime moieties, which are present as side chains on the sorbents, towards the uranyl moiety. The technological implications of some of the observed coordination modes are outlined. It is believed that X-ray crystallography of small uranyl-amidoxime molecules may help to build an understanding of the interactions of seawater uranyl with amidoxime-functionalized polymers and improve their recovery capacity and selectivity, leading to more efficient extractants. The challenges for scientists working on the structural elucidation of uranyl coordination complexes are also outlined. The review contains six sections and 95 references.
... 641-651, 2015, doi: 10.1016/ j.saa.2014.08.028. substances with an azomethine or imine (-C= N-) functional group are known as Schiff bases.In 1960, Hugo Schiff was the first to describe them as the condensation products of primary amines with aldehyde and ketone compounds(Tsantis et al. 2020). They may adjust the ligation features by changing their denticity and basicity, and they are stable. ...
... The Discovery of Schiff bases in the 18 th century has attracted attention in coordination chemistry 1 . Schiff bases containing an azomethine group (-HC=N) are formed by a nucleophilic condensation reaction of carbonyl compounds with primary amines, which are often synthesized using acid/base catalysts or heating conditions 2 . ...
p>In this study, we have outlined a conventional and user-friendly procedure for the production of (E)-1-(((5-ethyl-1,3,4-thiadiazol-2-yl)imino)methyl)naphthalen-2-ol (HL-1) and (E)-1-((thiazol-2-ylimino)methyl)-naphthalen-2-ol (HL-2) by the reaction of heterocyclic amine, aldehyde in the presence of ethanol as a solvent and acid as the catalyst. The synthesis of new HL-1 and HL-2 may be accomplished with ease using this approach, which is also very efficient. In the presence of dipositive Co, Ni, and Cu metal complexation, HL-1 and HL-2 were carried out in the presence of metal: ligand (1:2). HL-1, HL-2, and metal complexes are characterized with the assistance of UV/visible, FT-IR, Mass, and <sup>1</sup>H NMR spectroscopy respectively. Furthermore, the ligands mentioned above (HL-1 and HL-2) and their metal complexes were tested for the antimicrobial study and showed an excellent inhibitory zone. These investigations indicated that HL1 - Co (II), HL-1Cu (II), complexes and ligands HL-2Co (II), and HL-1Ni(II) had positive effects on Escherichia coli causing severe stomach cramps (Gram-negative- MTCC 1610) and positive impact on Staphylococcus aureus (Gram-positive MTCC - 96) due to skin infections.</p
... One of the most important advantages of the Schiff's base reaction is the opening up of the possibility to produce the "multiazomethine functionalized compounds" from the corresponding multi-carbonyl and/or amine derivatives. Among the "multiazomethine functionalized compounds", salen and salophen-type bis -Schiff bases are extensively studied compounds [38][39][40][41][42][43][44][45][46][47] . Over the years, numerous reviews and publications prove the interesting physicochemical properties and potential applications of these compounds and their metal complexes [ 19 , 36 , 43 , 48-55 ]. ...
Novel bi- and trinuclear palladium(II)-sodium complexes, {[PdL]Na(NO3)(EtOH)} (1) and {[PdL]2Na}Cl (2) based on salophen-type Schiff base N,N'-(1,2-phenylene)-bis(3-methoxysalicylideneimine) (H2L) were synthesized under ambient and sonochemical conditions. Ultrasonication proved to be a more effective method for the rapid synthesis of these bi- and trinuclear complexes under mild conditions. On the basis of the molecular structure of complexes 1 and 2, each palladium atom is placed in the “inner” N2O2 compartment, and the sodium atoms are located in the “outer” O2O’2 compartment of the twofold deprotonated bis-Schiff base ligand. In both complexes, each Pd(II) ion is four coordinated showing square planar geometry, whereas the Na(I) ions in complexes 1 and 2 adopt two different geometries, namely hepta and octa coordination, respectively. In addition, the solventless thermolysis of both complexes at 500 °C was also studied by thermal gravimetric analysis (TGA). EDX and powder XRD data pointed out the presence of highly pure nanoscaled materials. Furthermore, the anticancer and antibacterial activities of bi- and trinuclear complexes were examined towards MCF-7 human breast cancer cell line and evaluated against one gram-negative strain (Escherichia coli ATCC 25922) and one gram-positive strain (Staphylococcus aureus ATCC 6538). The in vitro studies revealed that complex 2 exhibited higher anticancer activity against MCF-7 cell line as well as better antibacterial effect on the examined bacteria strains than complex 1.
... Tsantis et al. [123] identified the novel track to lanthanoid (Ln) multielectron redox transfer [124], presenting the redox activity of tetradentate N, N, O, O-Schiff-bases. The studies of reactivity and electrochemical ones made on K 3 mononuclear complexes [Ln(bis-Rsalophen)] demonstrated that the complexes oxidation potential can be adjusted through the changing of the substituent at the ligand and that the complexes can act as formal two-electron reducers. ...
Because of their importance in a variety of interdisciplinary study domains, Schiff-base ligands have performed a significant role in the evolution of contemporary coordination chemistry. This almost-comprehensive review covers all the aspects and properties of complexes, starting from the Schiff-base ligands. Our work is centered on the eloquent advances that have been developed since 2015, with special consideration to recent developments. Schiff-base ligands and their complexes are adaptable compounds obtained from the condensation of two compounds: a carbonyl with an amino. The correspondent metal complexes have been shown to have antifungal, antibacterial, antioxidant, antiproliferative, and antiviral properties. This review begins with a short introduction to Schiff-base ligands and their metal complexes. It stands out in the recent advancements in the Schiff-base coordination chemistry domain and its future prospects as a potential bioactive core. Additionally, the review contains knowledge about the antioxidant, redox, and catalytic activities of the Schiff-base complexes, with important future applications in the obtaining of new compounds and materials.
