129409-01-4Relevant articles and documents
Luminescent bi-metallic fluoroborate derivatives of bulky salen ligands
Guieu, Samuel,Cardona, Francisco,Rocha, Joo,Silva, Artur M. S.
, p. 5411 - 5414 (2014)
A family of hemisalen fluoroborate complexes has been prepared and characterized. These new fluorophores exhibit an intense blue emission upon irradiation with UV light. Interestingly, the introduction of bulky aromatic substituents enhanced the quantum yield considerably, up to 44%. Upon studying various solvents, it appeared that the effect of the phenyl substituents is more of electron donating nature than of restricting the intramolecular motion of the dyes. This journal is
Synthesis, Characterization, Theoretical Studies, and Antimicrobial/Antitumor Potencies of Salen and Salen/Imidazole Complexes of Co (II), Ni (II), Cu (II), Cd (II), Al (III) and La (III)
Abdalla, Ehab M.,Abdel Rahman, Laila H.,Abdelhamid, Antar A.,Shehata, Mohamed R.,Alothman, Asma A.,Nafady, Ayman
, (2020)
Although salens and imidazoles are well-studied motifs among bioactive and therapeutic agents, their properties when combined in transition metal complexes are not well developed. To explore the structure/reactivity of this class of compounds, a salen-based ligand, namely (2,2′-{1,2-ethanediylbis[nitrilo(E)methylylidene]}diphenol, S), and its binary (MS) and ternary (MSI) complexes (I = imidazole; M = Co (II), Ni (II), Cu (II), Cd (II), Al (III), and La (III)) have been synthesized and fully characterized by standard physicochemical and theoretical methods. Evidence from structural analysis tools along with DFT modeling revealed an unusual monobasic tridentate salen binding mode, involving the phenolic oxygen, the nitrogen of the azomethine group, and NH group formed via phenol-to-cyclohexadienone tautomerization, giving rise to a general molecular formula of MSI complexes as [M(S)(I)2(Cl)] for M (II) = Co, Ni, Cu and Cd or [M(S)(I)(Cl)2] for M (III) = Al and La, respectively. The antimicrobial activities of S, MS, and MSI were screened against several bacterial and fungal strains. Of all tested complexes, CdS and CuSI were the most effective antimicrobials, giving larger inhibition zones than the reference antibiotics. The antimicrobial efficacy for the MS complexes follows the order: CdS > gentamicin > CuS > NiS > CoS > LaS > AlS > S, whereas MSI complex, potencies are ordered as CuSI > gentamicin > CdSI >NiSI > CoSI > LaSI > AlSI > S. In vitro cytotoxicity screening of MSI complexes disclosed that both CuSI and CdSI exhibited higher activity against human liver (Hep-G2) and breast (MDA-MB231) carcinoma cell lines than the reference (cisplatin) drug. The satisfactory bioactivities observed for several of these compounds supports the underlying design idea for combining important bioactive motifs for possible therapeutic benefit.
A family of silatrane-armed triazole-encapped salicylaldehyde-derived Schiff bases: Synthesis, spectral analysis, and antimicrobial and quantum chemical evaluation
Singh, Gurjaspreet,Arora, Aanchal,Rani, Sunita,Kalra, Pooja,Aulakh, Darpandeep,Wriedt, Mario
, (2017)
This work describes the successful synthesis of salicylaldehyde-derived Schiff base-linked organosilicon compounds following a highly efficient click approach. Hydroxyl-terminated Schiff bases were alkylated to bis-acetylenes (1–3) which upon 3?+?2 cycloaddition with 3-azidopropyltriethoxysilane yielded triazole-decorated bis-silanes (4–6). These silanes further underwent base-catalyzed transesterification to afford Schiff base-linked triazole-bound organosilatranes (7–9). The final silatranes as well as precursor alkynes and silanes were comprehensively characterized using NMR (1H and 13C) and infrared spectroscopic techniques together with elemental analysis and mass spectrometry of compounds 7–9. Also, the structures of alkynes 1–3 and silatrane 7 were validated using single-crystal X-ray crystallography. Organosilatranes were initially screened for their pharmacokinetic profile using absorption, distribution, metabolism, excretion and toxicity (ADMET) tools and then explored for their antimicrobial activities, with compound 9 emerging as the most potent antimicrobial agent. Compounds 1–3 and 7–9 also underwent thorough computational analysis by applying the density functional theory (DFT) approach with B3LYP/6-31G(d) level of theory and the results were found to be consistent with the experimental data. Several DFT-based descriptors were also evaluated providing a valuable insight into molecular stability and reactivity.
Uranyl stabilized Schiff base complex
Bharara, Mohan S.,Tonks, Stephen A.,Gorden, Anne E. V.
, p. 4006 - 4008 (2007)
Uranyl Schiff base complex [(UO2)2(Salpro)(OH) (Solvent)2] (1) in the presence of excess of ethylenediamine (EDA) does not undergo nucleophilic addition (hydrolysis) and substitution (transamination) reactions due to an extended chelation [2N, 3O + OH] by the flexible backbone. The Royal Society of Chemistry.
Methylene spacer-regulated structural variation in cobalt(II/III) complexes with bridging acetate and salen- or salpn-type Schiff-base ligands
Chattopadhyay, Shouvik,Drew, Michael G. B.,Ghosh, Ashutosh
, p. 1693 - 1701 (2008)
Two linear, trinuclear mixed-valence complexes, [CoII{(μ- L1)-(μ-OAc)CoIII(OAc)}2] (1) and [Co II{(μ-L2)(μ-OAc)CoIII(OAc)}2] (2) and two mononuclear CoIII complexes [CoIII{L 3}(OAc)] (3), and [CoIII{L4}(OAc)] (4) were prepared and the molecular structures of 1, 2 and 4 elucidated on the basis of X-ray crystallography [OAc = Acetate ion, H2L1 = H 2Salen = 1,6-bis(2-hydroxyphenyl)-2,5-diazahexa-1,5-diene, H 2L2 = H2Me2-Salen = 2,7-bis(2-hydroxyphenyl)-2,6-diazaocta-2,6-diene, H2L3 = H2Salpn = 1,7-bis(2-hydroxyphenyl)-2,6-diazahepta-1,6-diene, H 2L4 = H2Me2Salpn = 2,8-bis(2-hydroxyphenyl)-3,7-diazanona-2,7-diene]. In complexes 1 and 2, the acetate groups show both monodentate and bridging bidentate coordination modes, whereas chelating bidentate acetate is present in 4. The terminal Co IIIN2O4 centres in 1 and 2 exhibit uniform facial arrangements of both non-bridged N2O and bridging O 3 donor sets and the CoII centre is coordinated to six (four phenoxo and two acetato) oxygen atoms of the bridging ligands. The effective magnetic moment at room temperature corresponds to the presence of high-spin CoII in both 1 and 2. The complexes 1 and 2 are thus CoIII(S = 0)-CoII(S = 3/2)-CoIII(S = 0) trimers. Complexes 3 and 4 are monomeric and diamagnetic containing low-spin CoIII(S = 0) with chelating tetradentate Schiff base and bidentate acetate. Calculations based on DFT rationalise the formation of trinuclear or mononuclear complexes. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Mixed-ligand Ru(II) complexes with 2,2′-bipyridine and tetradentate Schiff bases auxiliary ligands: Synthesis, physico-chemical study, DFT analysis, electrochemical and Na+ binding properties
Mishra, Lallan,Prajapati, Rishikesh,Pandey, Krishna Kumar
, p. 79 - 85 (2008)
cis-Bis(2,2′-bipyridyl)dichlororuthenium(II)dihydrate complexed with Schiff bases salen (L1H2) and salophen (L2H2) provides complexes of compositions [Ru(L1)(bpy)2] 1 and [Ru(L2)(bpy)2] 2, respectively with cavity. The structure of these complexes characterized by spectroscopic studies were supported by their optimized geometries based on DFT calculations. Complexes 1 and 2 were then allowed to interact with methanolic solution of sodium perchlorate separately providing corresponding complexes 3 and 4 with the compositions 1·NaClO4 and 2·NaClO4, respectively. The formation constants were then evaluated by monitoring the changes in their UV-visible spectral features upon addition of different amount of sodium salts in the presence of a fixed concentration of the ruthenium complexes at a wavelength 294 nm. Emission (solution), luminescence microscopic and cyclic voltammetric studies of these complexes have also been made.
Synthesis, characterization, optical spectroscopic, electronic structure, and second-order nonlinear optical (NLO) properties of a novel class of donor-acceptor bis(salicylaldiminato)nickel(II) Schiff base NLO chromophores
Di Bella, Santo,Fragalà, Ignazio,Ledoux, Isabelle,Diaz-Garcia, Maria A.,Marks, Tobin J.
, p. 9550 - 9557 (1997)
The synthesis, characterization, thermal stability, optical spectroscopic, electronic structure, and second-order nonlinear optical (NLO) response of a series of donor-acceptor bis(salicylaldiminato)nickel(II) Schiff base complexes and the free ligand precursors are reported. The effect of the metal center in such complexes is manifold: it templates the formation of acentric molecular structures, imparts high thermal stability to the chelate ring, and both 'switches on' and enhances NLO response. Metal complexation imparts new linear optical spectroscopic features, having metal-to-ligand charge transfer character, which are responsible for the second-order nonlinearity. Moreover, the present synthetic strategy represents a novel route to inorganic NLO chromophores. Solution-phase hyperpolarizability values, deduced by electric field-induced second-harmonic-generation experiments are as high as -79 x 10-30 cm5 esu-1 (hω = 0.92 eV). Experimental linear and nonlinear optical features are fully consistent with INDO/SCI-SOS theoretical calculations. They provide a rationale for the NLO response of these materials and are attractive for designing new, highly efficient second-order nonlinear optical inorganic chromophores.
Synthesis, spectral and electrochemical studies of some Schiff base N 2O2 complexes
Shehata,Masoud,Khalil,Abdel-Gaber
, p. 149 - 158 (2014)
Schiff base metal complexes of different stoichiometries and modes of interactions were synthesized and characterized using different metals Mn, Co, Ni, Cu by elemental analysis, spectral (IR and UV-Vis) methods and magnetic susceptibility studies. Electrochemical studies were performed for some of Schiff base complexes (Cu-salpr, Cu-salen, and Cu-salph·H2O) and of H2-salen and its corresponding Ni, Co, and Cu complexes on the corrosion behaviour of steel in 1 M sulphuric acid solution and were studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The stoichiometry of Fe and Mn (salen, salpr and salph) complex was studied by using different spectrophotometric methods.
Cubane Structure of Sodium Derivatives of Tetradentate Schiff Bases
Solari, Euro,Angelis, Stefania De,Floriani, Carlo,Chiesi-Villa, Angiola,Rizzoli, Corrado
, p. 2471 - 2476 (1991)
Reaction of sodium hydride in thf (thf = tetrahydrofuran) with H2salphen or H2salen gave the corresponding sodium derivatives Na2(salphen)(thf)n and Na2(salen)(thf)n.Recrystallization from 1,2-dimethoxyethane (dme) gave the stable solvated forms 1 and 2.From the X-ray analysis both have very similar structures with a cubane skeleton of alternate sodium and oxygen atoms.Crystallographic details: complex 1, space group P21/c, a = 12.045(1), b = 25.851(2), c = 16.467(1) Angstroem, α = γ = 90 deg, β = 107.61(1) deg, Z = 4 and R = 0.079 for 2118 independent observed reflections; 2, space group P21/n, a = 20.493(2), b = 21.682(2), c = 20.538(2) Angstroem, α = 90 deg, β = 110.53(1) deg, Z = 8 and R = 0.071 for 5054 independent observed reflections.
One-pot two-step mechanochemical synthesis: Ligand and complex preparation without isolating intermediates
Ferguson, Michael,Giri, Nicola,Huang, Xu,Apperley, David,James, Stuart L.
, p. 1374 - 1382 (2014)
Although the use of ball milling to induce reactions between solids (mechanochemical synthesis) can provide lower-waste routes to chemical products by avoiding solvent during the reaction, there are further potential advantages in using one-pot multistep syntheses to avoid the use of bulk solvents for the purification of intermediates. We report here two-step syntheses involving formation of salen-type ligands from diamines and hydroxyaldehydes followed directly by reactions with metal salts to provide the corresponding metal complexes. Five salen-type ligands 2,2′-[1,2-ethanediylbis[(E)- nitrilomethylidyne]]bis-phenol, 'salenH2', 1; 2,2′-[(±)- 1,2-cyclohexanediylbis-[(E)-nitrilomethylidyne]]bis-phenol, 2; 2,2′-[1,2-phenylenebis(nitrilomethylidyne)]-bis-phenol, 'salphenH 2' 3; 2-[[(2-aminophenyl)imino]methyl]-phenol, 4; 2,2′-[(±)-1,2-cyclohexanediylbis[(E)-nitrilomethylidyne]]-bis[4, 6-bis(1,1-dimethylethyl)]-phenol, 'Jacobsen ligand', 5) were found to form readily in a shaker-type ball mill at 0.5 to 3 g scale from their corresponding diamine and aldehyde precursors. Although in some cases both starting materials were liquids, ball milling was still necessary to drive those reactions to completion because precipitation of the product and or intermediates rapidly gave in thick pastes which could not be stirred conventionally. The only ligand which required the addition of solvent was the Jacobsen ligand 5 which required 1.75 mol equivalents of methanol to go to completion. Ligands 1-5 were thus obtained directly in 30-60 minutes in their hydrated forms, due to the presence of water by-product, as free-flowing yellow powders which could be dried by heating to give analytically pure products. The one-armed salphen ligand 4 could also be obtained selectively by changing the reaction stoichiometry to 1:1. SalenH21 was explored for the one-pot two-step synthesis of metal complexes. In particular, after in situ formation of the ligand by ball milling, metal salts (ZnO, Ni(OAc)2·4H2O or Cu(OAc) 2·H2O) were added directly to the jar and milling continued for a further 30 minutes. Small amounts of methanol (0.4-1.1 mol equivalents) were needed for these reactions to run to completion. The corresponding metal complexes [M(salen)] (M = Zn, 6; Ni, 7; or Cu, 8) were thus obtained quantitatively after 30 minutes in hydrated form, and could be heated briefly to give analytically pure dehydrated products. The all-at-once 'tandem' synthesis of [Zn(salen)] 6 was also explored by milling ZnO, ethylene diamine and salicylaldehyde together in the appropriate mole ratio for 60 minutes. This approach also gave the target complex selectively with no solvent needing to be added. Overall, these syntheses were found to be highly efficient in terms of time and the in avoidance of bulk solvent both during the reaction and for the isolation of intermediates. The work demonstrates the applicability of mechanochemical synthesis to one-pot multi-step strategies.
