Naphthol Ligands Research Articles

Complexes of rare earth metals with bromine-substituted (benzoxazolyl)naphtholate ligands as emissive materials

A series of complexes [Ln(NpBrOON)3]2 (Ln = Nd, Eu, Gd, Yb) were synthesized by the reaction of the corresponding lanthanide silylamides with 2-(2-benzoxazol-2-yl)-7-bromo-3-naphthol. The structure of the initial phenol, Eu and Yb complexes was established using X-ray diffraction analysis, which showed that the resulting compounds have a centrosymmetric dimeric structure. All the obtained complexes in the solid state upon excitation by light with a wavelength of 365 nm revealed ligand-centered photoluminescence (PL) in the visible region of 450–700 nm. The complexes of Nd and Yb in addition exhibit the metal-ctntered emission in the near-infrared (NIR) region of high intensity.

Highly Efficient and One-pot New Betti Bases: PEG-400 and Al2O3 Mediated Synthesis, Optimizations, and Cytotoxic Studies

Background:: Multicomponent reactions (MCRs) have proven as one of the best alternatives to minimize several environmental consequences, mainly the use of hazardous chemicals, byproducts, and severe production processes. Literature reveals that MCRs with PEG-400 and metal oxide-based greener media provide a new and useful strategy for the construction of biologically potent organic systems. Objective:: The present study aimed to synthesize newer Betti bases by a modified Betti reaction employing a highly efficient catalyst for the direct synthesis of a novel class of non-racemic amino benzyl naphthol ligands under green solvent media. The involvement of the articulated framework (4a-4j) was studied against nine cancer panels (NCI-60 cell lines) in terms of inhibiting/killing cancer cells. Methods:: For the modification of the Betti reaction, we used 2-aminopyridin-3-ol, aromatic aldehydes, and a naphthol system using greener media employing PEG-400 and alumina as a prime active and highly selective catalyst. Furthermore, the antiproliferative activity against NCI-60 human cancer cell lines (GI50) was used for the development of pharmacologically active compounds and exhibited the single dose (10-5 M) study. Results:: Based on greener media synthesis, recompenses of ease of workup, less reaction time, higher yield, and higher atom economy, as well as environmentally friendly, were reported. Betti bases were obtained at a yield of 87-98% and characterized by spectroscopic techniques. Among the synthesized scaffolds, compound 4b was found to be extra potent in melanoma cancer [MDAMB- 435], while compound 4h showed promising inhibition in leukemic cancer cell lines [HL- 60(TB) and MOLT-4]. Conclusion:: A straightforward way for an efficient synthesis of Betti bases was developed via the reaction of naphthol and aldehydes with amines in PEG-400 media. An Al2O3 was effectively catalyzed in the Betti reaction in excellent yields without the formation of any other by-product in atom economy and environmentally benign way. The newly synthesized hybrids were tested in vitro against a panel of cancer cell lines, and some of the compounds exhibited significant inhibitory anti-proliferative effects. The most potent compounds (4b and 4h) showed interesting results, and compound 4b was found extra potent in melanoma cancer cell lines with -62% GI values.

Synthesis and Luminescent Properties of Lanthanide Complexes with Benzothiazolylphenolate and -Naphtholate Ligands

Sm, Er, and Yb complexes containing anionic (4,5,6,7-tetrafluorobenzothiazol-2-yl)-2-(3,4,5,6-tetrafluoro)phenolate (SONF) and 3-(2-benzothiazol-2-yl)-2-naphtholate (NpSON) and neutral 1,10-phenathroline or 2,2'-bipyridine ligands were synthesized. The structures of complexes Yb(SONF)2-(NpSON)(DME)1.5 (II) and previously synthesized Er(SONF)3(DME) (I) were determined by X-ray diffraction (CIF files CCDC nos. 1972769 and 1972770, respectively). Upon excitation by light at λ 405 nm, all complexes showed luminescence of the ligands and Ln3+ ions. The OLED devices based on samarium complexes showed moderate intensi metal-centered emission of moderate intensity at a 19 V voltage.

Synthesis and structural characterization of palladium(II) 2-(arylazo)naphtholate complexes and their catalytic activity in Suzuki and Sonogashira coupling reactions

A family of five palladium(II) 2-(arylazo)naphtholate complexes, [PdCl(PPh3)(L)] (L = O, N-donor of bidentate 2-(arylazo)naphtholate ligands), have been synthesized and characterized by elemental analysis and spectral (FT-IR, UV–Vis, 1H-NMR and 13C-NMR) methods. Further, the catalytic efficiency of all the complexes have been investigated for Suzuki and Sonogashira coupling reaction of various aryl halides.

Computer Simulation of the Destruction of the Organic Lanthanide Complexes under Ionizing Radiation

The calculation of defects in the structures of the Sc, La, Nd, Sm, Tb, and Yb complexes with substituted phenolate and naphtholate ligands formed under the action of neutrons with a mean energy of 2 MeV shows that the shifts of the target atoms depend on their masses and can achieve 1 μm for O, N, and S. A similar result is obtained for the calculation of the destruction of the Eu(TTA)3(DME)2 complex (HTTA is thenoyltrifluoroacetone). However, the treatment of the samples with the n,γ radiation does not result in destruction. Possible reasons for the found divergence between the calculated and experimental data are discussed.

Half-sandwich ruthenium(II) complexes containing O, N bidentate azo ligands: Synthesis, structure and their catalytic activity towards one-pot conversion of aldehydes to primary amides and transfer hydrogenation of ketones

The ruthenium(II) complexes of the general formula [Ru(η6‒p‒cymene)(Cl)(L1‒5)] (L = O, N-donors of biphenylazo derivatives), formed by reacting 2‒(biphenylazo)phenol (HL1‒ HL4) and 1‒(biphenylazo)naphthol ligands (HL5) with [{η6‒p‒cymene)RuCl}2(μ‒Cl)2] have been synthesized. The compositions of the complexes have been established by IR, UV–Vis, 1H NMR spectral methods and X-ray crystallography. The synthesized complex could act as an efficient, reusable homogeneous catalyst for transformation of aldehydes to the corresponding primary amides in the presence of NH2OH·HCl, thus resulting an expansion of Beckmann rearrangement. The effect of solvent, base, temperature, time, catalyst loading and recyclability was also investigated. They also effectively catalyze the transfer hydrogenation reaction of various ketones with 2-propanol.

Synthesis, Structure and Catalytic Oxidation of Ruthenium(III) Complexes Containing 1‐(Arylazo)naphthol Ligands Derived from β−Naphthol and Sterically Bulky Amines

AbstractA new class of ruthenium(III) complexes containing O, N donor functionalized azo derivatives were designed and synthesized. The synthesized compounds were characterized by fourier‐transform infrared (FTIR), ultraviolet–visible (UV‐vis) and electron paramagnetic resonance (EPR) spectral studies. The X−ray crystal structure of one of the complexes [Ru(L1)3] 1 has been determined. The catalytic activity of the complex [Ru(L1)3] 1 has been studied for the oxidation of primary and secondary alcohols to corresponding carbonyl compounds in the presence of N‐ Methylmorpholine‐N‐Oxide as co‐oxidant.

Synthesis, crystal structure of copper(II) complexes comprising 2-(biphenylazo)phenol and 1-(biphenylazo)naphthol ligands and their catalytic activity in nitroaldol reaction

New series of copper(II) complexes of the type [Cu(L)2] (L=L1–L5) comprising bidentate 2-(biphenylazo)phenol (HL1–HL4) and 1-(biphenylazo)naphthol (HL5) ligands have been synthesized. The composition of complexes and ligands (HL1–HL4) has been established by elemental analysis and spectral (FT–IR, UV–Vis, 1H NMR and EPR) methods. Molecular structures of copper complexes [Cu(L3)2] (3) and [Cu(L5)2] (5) were established by X-ray crystallography. These Copper(II) biphenylazo complexes exhibit a very good catalytic activity towards nitroaldol reaction of various aldehydes with nitromethane.

Synthesis, structure, redox behavior, catalytic activity and DFT study of a new family of ruthenium(III)1-(arylazo)naphtholate complexes

Treatment of [RuCl2(DMSO)4] with 1-(arylazo)naphthol ligands in benzene under reflux afford the air-stable new ruthenium(III) complexes with general composition [Ru(L-R)3] (L = bidentate O, N donor; R = H, CH3, OCH3, Br, NO2) in good yield. The 1-(arylazo)naphthol ligands behave as tris-bidentate O, N donors via naphtholic proton and azo nitrogen. The molecular and electronic structure of the complexes have been established by elemental analysis and spectral (FT-IR, UV–vis & EPR) methods. DFT calculations were also carried out on the complexes 1 and 3 along with X-ray crystallized geometry of complex 5. These complexes in dichloromethane solution show intense ligand-to-metal charge transfer (LMCT) transitions in the visible region. The absorption and g-tensor value of these complexes (1, 3 & 5) were also computed and compared along with the available experimental results. The redox behavior of the complexes has been investigated by cyclic voltammetry and the potentials are observed with respect to the electronic nature of substituents (R) in the 1-(arylazo)naphthol ligands. These complexes have shown great promise as catalysts for the conversion of aldehydes to primary amides in good yield.

Functionalizing the glycocalyx of living cells with supramolecular guest ligands for cucurbit[8]uril-mediated assembly.

Multiple naphthol ligands were installed on the glycocalyx of white blood cells via metabolic labeling and subsequent strain promoted azide-alkyne cycloaddition. Only when cucurbit[8]uril was present to drive the formation of ternary complexes, cells specifically assembled on a methylviologen functionalized supported lipid bilayer through multivalent interactions.

Substituted naphtholates of rare earth metals as emissive materials

The synthesis, characterization, photoluminescent (PL) and electroluminescent (EL) behavior of trivalent Sc, Nd, Gd, Er, Tm and Yb complexes with 3-(5-methylbenzoxazol-2-yl)naphthol (L-5Me) and 3-(6-methylbenzoxazol-2-yl)naphthol (L-6Me) ligands are reported.

Lanthanide complexes with substituted naphtholate ligands: extraordinary bright near-infrared luminescence of ytterbium

A series of Pr, Nd, Ho, Er, Tm, and Yb complexes with 3-(2-benzoxazol-2-yl)-2-naphtholate and 3-(2-benzothiazol-2-yl)-2-naphtholate ligands was synthesized. The structure, as well as the photo- and electroluminescent properties of these complexes were studied. An extraordinary bright emission of Yb3+ was detected. To explain the phenomenon, a novel excitation mechanism involving intramolecular electron transfer was proposed.

Oxorhenium(V) Complexes with Pyrazole Based Aryloxide Ligands and Application in Olefin Epoxidation

We synthesized and characterized a set of new oxorhenium(V) complexes coordinated by various pyrazole containing phenol (L1-L3) and naphthol ligands (L4-L7). Depending on the starting material, we were able to selectively synthesize monosubstituded or disubstituted complexes of the type [ReOBr(2)L(PPh(3))] (1-7; L = L1-L7) and [ReOClL(2)] (L = L1 8; L2 9; L4 10; L6 11), respectively. All complexes are stable to air and moisture, both in solid state as well as in solution. Furthermore, the cationic oxorhenium(V) complex [ReO(L1)(2)(NCMe)](OTf) (8a) was obtained upon chloride abstraction with silver triflate from 8. All new complexes were able to catalyze the epoxidation of cis-cyclooctene in yields up to 64%. The ease of preparation and their tolerance to air and moisture, as well as the simple ligand modifications, make them an interesting class of novel catalysts. An attempted reduction of perchlorate ClO(4)(-) with complex 8 was unsuccessful. Molecular structures of complexes 1, 4, 6, 7, 8, 8a, 10, and 11 were determined by single crystal X-ray diffraction analyses.

Ruthenium(III) mediated C–H activation of azonaphthol: Synthesis, structural characterization and transfer hydrogenation of ketones

Treatment of [RuCl 3(PPh 3) 3] with 1-(arylazo)naphthol ligands in benzene under reflux afford air-stable new organoruthenium(III) complexes with general composition [Ru(an-R)Cl(PPh 3) 2] (where, R = H, Cl, CH 3, OCH 3, OC 2H 5) in fairly good yield. The 1-(arylazo)naphtholate ligands behave as dianionic tridentate C, N, O donors and coordinates to ruthenium through phenolic oxygen, azo nitrogen and ortho carbon generate two five-membered chelate rings. The composition of the complexes have been established by analytical (elemental analysis and magnetic susceptibility measurement) and spectral (FT-IR, UV–Vis, EPR) methods. The complexes are paramagnetic (low-spin, d 5) in nature and in dichloromethane solution show intense d–d transitions and ligand-to-metal charge transfer (LMCT) transitions in the visible region. The solution EPR spectrum of complex [Ru(an-CH 3)Cl(PPh 3) 2] ( 3) in dichloromethane at 77 K shows rhombic distortion around the ruthenium ion with three different ‘ g’ values ( g x ≠ g y ≠ g z ). The single crystal structure of the complex [Ru(an-OCH 3)Cl(PPh 3) 2] ( 4) has been characterised by X-ray crystallography, indicates the presence of a distorted octahedral geometry in these complexes. All the complexes exhibit one quasi-reversible oxidative response in the range 0.60–0.79 V (Ru IV/Ru III) and two quasi-reversible reductive responses (Ru III/Ru II; Ru II/Ru I) within the range −0.50 to −0.62 V and −0.93 to −0.98 V respectively. The formal potential of all the couples correlate linearly with the Hammett constant of the para substituent in arylazo fragment of the 1-(arylazo)naphtholate ligand. Further, the catalytic efficiency of one of the ruthenium complexes ( 4) was determined for the transfer hydrogenation of ketones with an excellent yield up to 99% in the presence of isopropanol/KOH.

Models for the Molybdenum Hydroxylases: Synthesis, Characterization and Reactivity of cis-Oxosulfido-Mo(VI) Complexes

Atom transfer reactions have been employed to convert Tp(i)(Pr)MoO(2)(OAr) into monomeric cis-oxosulfido-Mo(VI) and dimeric mu-disulfido-Mo(V) species, [Tp(i)(Pr)MoOS(OAr)](n)() (Tp(i)(Pr) = hydrotris(3-isopropylpyrazol-1-yl)borate; OAr = phenolate or naphtholate derivative; n = 1 and 2, respectively). Dark red, monomeric Tp(i)(Pr)MoOS(OAr) complexes contain distorted octahedral cis-oxosulfido-Mo(VI) centers, with d(Mo=O) = 1.692(5) A, d(Mo=S) = 2.132(2) A, and angle(O=Mo=S) = 103.68(16) degrees for the 2-sec-butylphenolate derivative. Dark red-purple, dimeric [Tp(i)(Pr)MoOS(OAr)](2) complexes undergo S-S bond cleavage forming monomeric oxosulfido-Mo(VI) species in solution. In the solid state, the 3,5-di-tert-butylphenolate derivative exhibits a centrosymmetric structure, with distorted octahedral anti oxo-Mo(V) centers bridged by a disulfido-kappaS,kappaS' ligand. Hydrolysis of the oxosulfido-Mo(VI) complexes results in the formation of [Tp(i)(Pr)MoO](2)(mu-S(2))(mu-O). In anaerobic solutions, certain oxosulfido-Mo(VI) complexes convert to molybdenyl complexes bearing bidentate 2-mercaptophenolate or related naphtholate ligands formed via intramolecular attack of the sulfido ligand on a coligand C-H group. The oxosulfido-Mo(VI) complexes serve as precursors to biologically relevant Mo(V) and heterobimetallic MoO(mu-S)Cu species and undergo a range of biomimetic reactions.