Tridentate Chelating Ligand Research Articles

Optical characteristics of synthetic Cu2+ complex films derived from 4-chloro-N-(3-(hydroxyimino) butan-2-ylidene) benzohydrazide for optoelectronic and photovoltaic applications

This study focuses on the creation and characterisation of Cu2+ complexes using the ONN tridentate chelating ligand, 4-chloro-N'-(3-(hydroxyimino) butan-2-ylidene) benzohydrazide (H2CIB). Synthetics were structurally investigated using a variety of elemental, molar conductivity, magnetic moment measurements and spectroscopic (1D-NMR, UV−Vis, FT-IR, and E-mass) tools as well as theoretically. The data from these analyses revealed that the hydrazone-oxime ligand acted as a mono-negative or neutral tridentate chelator, bonding the Cu2+ ions through the enolo/ketono carbonyl oxygen, protonated oximatic nitrogen, and azomethine nitrogen atoms, resulting in the formation of a square plane structure. In addition, the optical properties of these synthetics were studied. Based on the measured film reflectance, the index of refraction and extinction (k)/absorption (α) coefficient were determined through Kramers-Kronig (K-K) analysis. The optical band gap Eg value is estimated experimentally by different methods. The hydrazone-oxime ligand has the highest value of Eg where the complexes have Eg = 1.76, 1.83 and 1.76 eV for Cu2+- HCIBCuNO3, HCIBCuCl, and H2CIBCuSO4 samples, respectively. The Eg of CdSe is 1.74 eV which is very close to the Eg value of HCIBCuNO3, and H2CIBCuSO4. Therefore, the HCIBCuNO3, and H2CIBCuSO4 can replace the CdSe in all photovoltaic applications, photosensors and solar cells. With the help of n and k values the complex dielectric constant (ε⌣=εr+iεi)) and conductivity (σ⌣=σr+iσi) have been investigated over the whole spectral range. Furthermore, the first (χ(1)) and third (χ(3)) orders of nonlinear optical susceptibilities and the non-linear index (n2) of refraction has been estimated. According to the estimated values of χ(1), χ(3) and n2 the HCIBCuNO3, HCIBCuCl, and H2CIBCuSO4 can be considered as competitors to be used in optical switching gadgets, optical modulators, and optical signal processing.

Tridentate chelating ligand based fluorescent Zn(ii) coordination compounds for highly selective detection of picric acid

Two Zn(ii) complexes with 1-((2-pyridylmethyl)iminomethyl)-2-naphthol ligand show sensitive response to nitroaromatic explosives through luminescence quenching effects. The phenomenon was studied through time-dependent fluorescence technique.

Metal-Chelated Polymeric Nanomaterials for the Removal of Penicillin G Contamination.

We developed selective and relatively low-cost metal-chelated nanoparticle systems for the removal of the penicillin G (Pen G) antibiotic, presented for the first time in the literature. In the nanosystem, poly(glycidyl methacrylate) nanoparticles were synthesized by a surfactant-free emulsion polymerization method and covalently bound with a tridentate-chelating ligand, iminodiacetic acid, based on the immobilized metal chelate affinity technique. It was modified with Cu2+, a chelating metal, to make Pen G specific. Metal-chelated nanoparticles were characterized by Fourier-transform infrared spectroscopy, energy dispersive spectrometry, zeta dimensional analysis, and scanning electron microscopy technology. Optimization studies of the Pen G removal were conducted. As a result of this study, Pen G removal with the p(GMA)-IDA-Cu2+ nanoparticle reached its maximum adsorption capacity of 633.92 mg/g in the short time of 15 min. The Pen G adsorption of p(GMA)-IDA-Cu2+ was three times more than that of the p(GMA) nanoparticles and two times more than that of the ampicillin adsorption. In addition, there was no significant decrease in the adsorption capacity of Pen G resulting from the repeated adsorption-desorption process of metal-chelated nanoparticles over five cycles. The metal-chelated nanoparticle had an 84.5% ability to regain its ability to regenerate the product with its regeneration capability, making the widespread use of the system very convenient in terms of reducing cost, an important factor in removal processes.

Synthesis and Characterization of Neutral Cyclometalated Platinum(II) Complexes and their Antibacterial and Cytotoxic Evaluations

AbstractA series of neutral cyclometalated platinum(II) complexes bearing 2,6‐bis(2‐naphthyl)pyridine as a C^N^C tridentate chelating ligand with monodentate pyridyl ligands with different substituents 1–3 have been synthesized via double cyclometalation and ligand displacement reaction. The structural, photophysical, electrochemical and aggregation induced emission (AIE) properties of these neutral platinum(II) complexes were systematically studied. Complexes 1–3 exhibited AIE effects with different emission intensities and colors, in which 1 showed the highest quantum efficiency of 8.6 % under aggregated state, and the aggregates were assembled to ordered spheres. Among the Pt(II) complexes, 1 showed a bactericidal activity against both Staphylococcus aureus (S. aureus) (MIC and MBC=3.13 μg/mL) and methicillin‐resistant S. aureus (MRSA) (MIC and MBC=6.25 μg/mL). Complex 1 did not possess noticeable cytotoxicity to human skin HaCaT keratinocytes. The non‐cytotoxic complex 1 would have a good potential to be used for the antibacterial therapy to combat with S. aureus and MRSA‐infected skin diseases.

Amplification of circularly polarized luminescence from chiral cyclometalated platinum(II) complexes by the formation of excimer

Circularly polarized organic light-emitting diodes (CP-OLEDs) have raised increasing interests owing to their potential application in next-generation displays. In this work, by introducing chiral alkyl chain into tridentate chelating ligand 2,6-bis(N-alkylbenzimidazol-2’-yl)benzene, three chiral Pt(II) complexes are successfully designed and synthesized. All the complexes exhibited bright green emission in dilute acetonitrile solution, while strong yellow-orange emission in highly concentrated solution. However, when these complexes are doped into polymer polymethyl methacrylate, the green emission stemmed from the intrinsic single molecule would be changed into red emission from excimer through adjusting the doping levels. More importantly, the CPL signals could be amplified by an order of magnitude in comparison with solution state. Furthermore, the monochrome devices based on these complexes were successfully fabricated, and achieved good device performances with the maximum luminance of up to 1720 cd m−2 and electroluminescence dissymmetry values of around 2.6 × 10−3. These results indicate that such design strategy for Pt(II) complexes with tridentate cyclometalled ligands would be important for the development of high-performance CP-OLEDs.

Linear dicarboxylato and tridentate chelating ligands coordinated Cu(II) complexes: Syntheses, crystal structures, protein binding and cytotoxicity studies

Three dinuclear copper(II) complexes, [Cu2(L1)2(tp)]∙4H2O (1), [Cu2(L1)2(ppda)(H2O)2]∙2H2O (2) and [Cu2(L2)2(tp)(CH3OH)2]∙2H2O (3) (where HL1 = 2-methoxy-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol, HL2 = 2-ethoxy-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol, tp = terephthalate, ppda = p-phenylenediacrylate), have been synthesized and characterized by single crystal X-ray diffraction, FTIR, mass spectrometry and thermal analysis. All the complexes crystallize in the monoclinic system with the space group P21/n (for 1 and 2) and P21/c (for 3) as centrosymmetric species. In 1 and 3, two CuL1 and CuL2 units, respectively are bridged by a terephthalate (tp) anion, whereas in 2 the bridging unit is p-phenylenediacrylate (ppda). The copper atoms in 1 exhibit a square planar coordination geometry, while in 2 and 3 the metals have a square pyramidal environment. All of 1–3 form 1D supramolecular chains through C-H…π interaction. The interaction of the complexes with bovine serum albumin (BSA) was investigated using a fluorescence spectroscopic technique. The values of the binding constant are (15.9 ± 0.13) × 104 M−1 (for 1), (10.3 ± 0.08) × 104 M−1 (for 2) and (11.2 ± 0.37) × 104 M−1 (for 3). Using the Scatchard equation, the calculated values of the number of binding sites (n) are all around 1, signifying the presence of a single binding site in serum albumins for the Cu(II) complexes. The cytotoxicity of the complexes was tested using breast cancer MCF7 and MDA-MB-231 cells, along with normal breast epithelial MCF10A cells. MTT results reveal that the complexes potently suppressed the growth of the breast cancer cell lines MCF7 and MDA-MB-231, and the MCF10A cells. Complexes 1–3 inhibited fifty percent growth (IC50) at 5.80 ± 1.47, 20.85 ± 1.25 and 5.10 ± 1.23 μM for MCF7 cells, respectively. Treatment of complex 3 results in perturbation of the microtubule organization, which might be through attenuation of the tubulin level.

Click inspired novel pyrazole-triazole-persulfonimide & pyrazole-triazole-aryl derivatives; Design, synthesis, DPP-4 inhibitor with potential anti-diabetic agents

This work presented the first report on designing, synthesizing of novel pyrazole-triazole-persulfonimide (7a-i) and pyrazole-triazole-aryl derivatives (8a-j) via click reaction using CuI catalyst and evaluated for their anti-diabetic activity and DPP-4 inhibitory effect. Click reactions went smoothly with CuI catalyst in the presence of tridentate chelating ligands and produced copper-free target pyrazole-triazole-persulfonimide analogues in excellent yield at RT. The designed compounds were docked against DPP-4 enzyme and showed excellent interaction with active amino acids residue. Further, all novel pyrazole-triazole-persulfonimide and pyrazole-triazole derivatives were subjected to enzyme-based in vitro DPP-4 inhibitory activity. Based on the SAR study DPP-4 inhibitory capacity compounds 7f (9.52 nM) and 8h (4.54 nM) possessed the significant inhibition of DPP-4. Finally compounds 7f and 8h were evaluated for their in vivo anti-diabetic activity using STZ induced diabetic mice model, and 8h showed a significant diabetic control effect compared to the sitagliptin drug. These studies demonstrated that the novel pyrazole-triazole-persulfonimide and pyrazole-triazole-aryl derivatives might be used as the leading compounds to develop novel DPP-4 inhibitors as potential anti-diabetic agents.

Synthesis, Crystal Structures of Gadolinium(III) and Erbium(III) Complexes Derived from Pyridine-2,6-Dicarboxylic Acid and Fluorescent Sensing of Picric Acid

Two new complexes of gadolinium(III) and erbium(III) with pyridine-2,6-dicarboxylic acid (H2Pydc),{Na3[Gd(Pydc)3]·2H2O}n (I) and [Er(HPydc)3]·10H2O (II), were prepared and their crystal structures were determined by X-ray crystallography (CIF files CCDC nos. 940633 (I) and 872068 (II)). The gadolinium atom in I is nine-coordinate (GdN3O6) and exhibits a tricapped trigonal prismatic geometry having 14 triangular faces. The Pydc ligand adopts chelating and, μ3- and μ5-bridging coordination modes. The 1D chains are further joined by Na atoms to generate a 3D coordination polymer. The structure is additionally stabilized by H-bonding. The Erbium polyhedron in II is also a tricapped trigonal prism (ErN3O6). The HPydc anions in II behave as tridentate chelating ligands. The complex molecules are connected to each other through hydrogen bonding interactions to form a three-dimensional network. Fluorescence titration experiments for complex II displayed highly sensitive fluorescence quenching efficiency of 98.3% against picric acid.

Systematic DFT Studies on Binary Pseudo-tetrahedral Zintl Anions: Relative Stabilities and Reactivities towards Protons, Trimethylsilyl Groups, and Iron Complex Fragments.

Binary pseudo‐tetrahedral Zintl anions composed of (semi)metal atoms of the p‐block elements have proven to be excellent starting materials for the synthesis of a variety of heterometallic and intermetalloid transition metal–main group metal cluster anions. However, only ten of the theoretically possible 48 anions have been experimentally accessed to date as isolable salts. This brings up the question whether the other species are generally not achievable, or whether synthetic chemists just have not succeeded in their preparation so far. To contribute to a possible answer to this question, global minimum structures were calculated for all anions of the type (TrTt3)5−, (TrPn3)2−, and (Tt2Pn2)2−, comprising elements of periods 3 to 6 (Tr: triel, Al⋅⋅⋅Tl; Tt: tetrel, Si⋅⋅⋅Pb; Pn: pnictogen, P⋅⋅⋅Bi). By analyzing the computational results, a concept was developed to predict which of the yet missing anions should be synthesizable and why. Additionally, the results of an electrophilic attack by protons or trimethylsilyl groups or a nucleophilic attack by transition metal complex fragments are described. The latter yields butterfly‐like structures that can be viewed as a new form of adaptable tridentate chelating ligands.

Specific Features of Monomeric Octahedral Monooxo d2-Rhenium(V) Complexes with Oxygen Atoms of Tridentate Chelating (О, N, N) Ligands (Review)

Specific features of the structures of 35 mononuclear octahedral monooxo d2-Re(V) complexes with tridentate chelating (О, N, N) ligands [ReO($${\text{L}}_{{{\text{tri}}}}^{m}$$)($${\text{L}}_{{{\text{bi}}}}^{n}$$)], [ReO($${\text{L}}_{{{\text{tri}}}}^{m}$$)(Hal)2], and [ReO($${\text{L}}_{{{\text{tri}}}}^{m}$$)Cl(PPh3)] have been considered. It has been demonstrated that, in most of compounds, the Re–O($${\text{L}}_{{{\text{tri}}}}^{m}$$)trans bonds are comparable in length (or somewhat shorter than) with the Re–O($${\text{L}}_{{{\text{tri}}}}^{m}$$)cis or Re–O(ST) bonds. This is evidence that the structure contains pseudodioxo ReO2 groups with an increased multiplicity of both Re–O bonds trans to each other. In the structures of eight compounds, the Re–O(Ltri)trans bonds are noticeably longer than Re–O(ST) and Re–O(Ltri)cis owing to the structural manifestation of the trans influence of a multiply bonded oxo ligand.

Glyphosate in livestock: feed residues and animal health1.

Glyphosate is a nonselective systemic herbicide used in agriculture since 1974. It inhibits 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase, an enzyme in the shikimate pathway present in cells of plants and some microorganisms but not human or other animal cells. Glyphosate-tolerant crops have been commercialized for more than 20 yr using a transgene from a resistant bacterial EPSP synthase that renders the crops insensitive to glyphosate. Much of the forage or grain from these crops are consumed by farm animals. Glyphosate protects crop yields, lowers the cost of feed production, and reduces CO2 emissions attributable to agriculture by reducing tillage and fuel usage. Despite these benefits and even though global regulatory agencies continue to reaffirm its safety, the public hears conflicting information about glyphosate's safety. The U.S. Environmental Protection Agency determines for every agricultural chemical a maximum daily allowable human exposure (called the reference dose, RfD). The RfD is based on amounts that are 1/100th (for sensitive populations) to 1/1,000th (for children) the no observed adverse effects level (NOAEL) identified through a comprehensive battery of animal toxicology studies. Recent surveys for residues have indicated that amounts of glyphosate in food/feed are at or below established tolerances and actual intakes for humans or livestock are much lower than these conservative exposure limits. While the EPSP synthase of some bacteria is sensitive to glyphosate, in vivo or in vitro dynamic culture systems with mixed bacteria and media that resembles rumen digesta have not demonstrated an impact on microbial function from adding glyphosate. Moreover, one chemical characteristic of glyphosate cited as a reason for concern is that it is a tridentate chelating ligand for divalent and trivalent metals; however, other more potent chelators are ubiquitous in livestock diets, such as certain amino acids. Regulatory testing identifies potential hazards, but risks of these hazards need to be evaluated in the context of realistic exposures and conditions. Conclusions about safety should be based on empirical results within the limitations of model systems or experimental design. This review summarizes how pesticide residues, particularly glyphosate, in food and feed are quantified, and how their safety is determined by regulatory agencies to establish safe use levels.

Structural Features of Monomeric Octahedral d2-Rhenium(V) Monooxo Complexes with Oxygen Atoms of Tridentate Chelating (O,N,S) Ligands

Structural Features of Monomeric Octahedral d2-Rhenium(V) Monooxo Complexes with Oxygen Atoms of Tridentate Chelating (O,N,S) Ligands

Structure of Monomeric Octahedral d2-Rhenium(V) Monooxo Complexes [ReO(Ltri)(Lbi)] and [ReO(Ltetra)(Lmono)] with Oxygen Atoms of Tridentate (O, O, O) and Tetradentate (O, O, O, O) Chelating Ligands

The structural features of four mononuclear octahedral d2-Re(V) monooxo complexes [ReO(Ltri)(Lbi)] and [ReO(Ltetra)(Lmono) with tridentate (O, O, O) and tetradentate (O, O, O, O) chelating ligands are discussed. It is shown that the Re–O(Ltri)trans bonds are elongated, whereas the Re–O(Ltetra)trans bonds are shortened as compared to the Re–O(L)cis bonds.

Structural Features of Monomeric Octahedral d2-Rhenium(V) Monooxo Complexes with Oxygen Atoms of Tridentate Chelating (O,P,O and O,P,N) Ligands

The structural features of 31 mononuclear octahedral d2-Re(V) monooxo complexes with tridentate chelating (O,N,S) ligands, [ReO $$\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)$$ $$\left( {{\text{L}}_{{{\text{bi}}}}^{n}} \right)$$ ] and [ReO $$\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)$$ (Lmono)2] (Lmono = Cl, Br, OMe, OPPh3, PPh3) are considered. The Re–O $${{\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)}_{{trans}}}{\kern 1pt} ,$$ Re–O $${{\left( {{\text{L}}_{{{\text{bi}}}}^{n}} \right)}_{{trans}}}{\kern 1pt} ,$$ and Re–O(OMe) bonds in 14 complexes were found to be commensurable in length with (or shorter than) analogous cis-bonds. This indicates the presence of pseudo-dioxo ReO2 groups in these structures with increased orders of both Re–O bonds located in trans-positions relative to each other. In the structures of 12 compounds, the Re–O(Ltri)trans, Re–O(Lbi)trans, and Re–O(OPPh3) bonds are markedly longer than analogous cis-bonds in accordance with the structural consequences of the trans-effect of a multiply bonded oxo ligand.

Four-Coordinate Boron Emitters with Tridentate Chelating Ligand for Efficient and Stable Thermally Activated Delayed Fluorescence Organic Light-Emitting Devices.

A new class of four-coordinate donor-acceptor fluoroboron-containing thermally activated delayed fluorescence (TADF) compounds bearing a tridentate 2,2'-(pyridine-2,6-diyl)diphenolate (dppy) ligand has been successfully designed and synthesized. Upon varying the donor moieties from carbazole to 10H-spiro[acridine-9,9'-fluorene] to 9,9-dimethyl-9,10-dihydroacridine, these boron derivatives exhibit a wide range of emission colors spanning from blue to yellow with a large spectral shift of 2746 cm-1 , with high PLQYs of up to 96 % in the doped thin film. Notably, vacuum-deposited organic light-emitting devices (OLEDs) made with these boron compounds demonstrate high performances with the best current efficiencies of 55.7 cd A-1 , power efficiencies of 58.4 lm W-1 and external quantum efficiencies of 18.0 %. More importantly, long operational stabilities of the green-emitting OLEDs based on 2 with half-lifetimes of up to 12 733 hours at an initial luminance of 100 cd m-2 have been realized. This work represents for the first time the design and synthesis of tridentate dppy-chelating four-coordinate boron TADF compounds for long operational stabilities, suggesting great promises for the development of stable boron-containing TADF emitters.

Four‐Coordinate Boron Emitters with Tridentate Chelating Ligand for Efficient and Stable Thermally Activated Delayed Fluorescence Organic Light‐Emitting Devices

AbstractA new class of four‐coordinate donor‐acceptor fluoroboron‐containing thermally activated delayed fluorescence (TADF) compounds bearing a tridentate 2,2′‐(pyridine‐2,6‐diyl)diphenolate (dppy) ligand has been successfully designed and synthesized. Upon varying the donor moieties from carbazole to 10H‐spiro[acridine‐9,9′‐fluorene] to 9,9‐dimethyl‐9,10‐dihydroacridine, these boron derivatives exhibit a wide range of emission colors spanning from blue to yellow with a large spectral shift of 2746 cm−1, with high PLQYs of up to 96 % in the doped thin film. Notably, vacuum‐deposited organic light‐emitting devices (OLEDs) made with these boron compounds demonstrate high performances with the best current efficiencies of 55.7 cd A−1, power efficiencies of 58.4 lm W−1 and external quantum efficiencies of 18.0 %. More importantly, long operational stabilities of the green‐emitting OLEDs based on 2 with half‐lifetimes of up to 12 733 hours at an initial luminance of 100 cd m−2 have been realized. This work represents for the first time the design and synthesis of tridentate dppy‐chelating four‐coordinate boron TADF compounds for long operational stabilities, suggesting great promises for the development of stable boron‐containing TADF emitters.

Structural Features of Monomeric Octahedral Monooxo d2-Rhenium(V) Complexes [ReO(Ltrin)(Lmono)2] and [ReO(Ltrin)(Lbim)] with Oxygen Atoms of Tridentate Chelating (O, N, O) Ligands (Ltrin) (Review)

Structural features of 22 mononuclear octahedral monooxo d2-Re(V) complexes with tridentate chelating (О, N, О) ligands (Ltrin)—[ReO(Ltrin)(Lmono)2] and [ReO(Ltrin)(Lbim)] (Lmono is a monodentate ligand, is a bidentate ligand)—have been considered. Conditions for selecting ligands that can be located trans to the multiply bonded O(oxo) ligand are discussed.

P‐Toluate‐bridged dinuclear Cu(II) complexes in combination with tridentate chelating ligand: Crystal structure, density functional theory calculation, DNA/protein binding and catecholase activity

The dinuclear Cu(II) complexes [Cu2(L1)2(mb)]⋅ClO4 (1) and [Cu2(L2)2(mb)]⋅ClO4 (2) (HL1 = 2‐[(2‐diethylaminoethylimino)methyl]phenol; HL2 = 2‐[1‐(2‐diethylaminoethylimino)propyl]phenol; mb = 4‐methylbenzoate) were synthesized and characterized using X‐ray crystal structure analysis and spectroscopic methods. Complexes 1 and 2 are dinuclear with distorted square pyramidal Cu (II) geometries, where Schiff base coordinates with tridentate (N,N,O) chelating mode and mb bridges two metal centres. Optimized structures and photophysical properties of ligands and complexes were calculated using density functional theory and time‐dependent density functional theory methods using B3LYP functional with 6‐31G (d,p) and LanL2MB basis sets. Interactions of the complexes with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using UV–visible absorption and fluorescence spectroscopies and the calculated values of association constants (M−1) are 1.7 × 105 (1–BSA), 5.7 × 105 (2–BSA), 1.6 × 105 (1–HSA) and 6.9 × 105 (2–HSA). Interactions of the complexes with calf thymus DNA were also investigated and the binding affinities are 1.4 × 105 and 1.6 × 105 M−1 for 1 and 2, respectively. Both complexes catalytically oxidize 3,5‐di‐tert‐butylcatechol to 3,5‐di‐tert‐butylbenzoquinone in the presence of molecular oxygen.

New Metallacyclic Derivatives of Aluminium(III) Stabilized with Bi- and Tridentate Chelating Ligands as Ring Opening Polymerization Catalysts of e-Caprolactone

New Metallacyclic Derivatives of Aluminium(III) Stabilized with Bi- and Tridentate Chelating Ligands as Ring Opening Polymerization Catalysts of e-Caprolactone

“SYNTHESIS AND SPECTRAL STUDIES OF Co(II) AND Ni(II) COMPLEXES WITH SCHIFF BASE LIGAND 1,6-DIMERCAPTO-1,6 DIAMINO-2,4,5-TRIAZA-3-PHENYL-3-HEXENE”

Complexes of 1,6 Dimercapto 1,6 Diamino 2,4,5 Triaza 3- Phenyl 3-hexene (MAAPHE) with bivalent metal ion of composition [ML2]X2 M= Co(II) and Ni(II), X=Cl-, Br-, NO3 - have been synthesized and characterized using physico-chemical and spectroscopic data. The ligan tridentate chelating ligand for the metal ions and the complexes are found to be octahedral in geometry.