Search

Comprehensive Summary: The privileged C2‐symmetric rigid phenol‐type ligand is more attractive but challenging in asymmetric catalysis. Herein, we designed and synthesized a class of rigid‐featured chiral tridentate Phenol‐2NO ligands, that incorporate the advantages of both the phenol skeleton and pyrroloimidazolone‐based N‐oxide moiety, from readily available L‐prolinamides in operationally simple two steps and up to 44% overall yield. More importantly, using an achiral quinoline derivative as an additive, the newly developed Phenol‐2NO ligand could serve as the anioic ligand upon deprotonative activation to coordinate to Zn(II) to form a highly enantioselective catalyst for the asymmetric Michael‐type Friedel‐Crafts alkylation reaction of indoles with 2,3‐dioxopyrrolidines. Excellent yields (up to 90%) and high enantioselectivities (up to 99% ee) are obtained for a wide range of substrates under mild conditions. Experiments and DFT calculations revealed the reaction mechanism and the origins of the enantioselectivity. This also represented the first activation of phenol‐type ligand/metal complex by an achiral organic base as the additive in asymmetric catalysis. [ABSTRACT FROM AUTHOR]

We synthesized arsenic analogs of a tridentate PPP ligand, bis[2‐(diphenylphosphino) phenyl] phenylphosphine, achieving yields of 40 % to 71 %. Additionally, we prepared copper (I) halide (CuX, X=Br, I) complexes with these ligands, with yields between 43 % and 84 %. Using both experimental and computational methods, we examined their structures and photophysical characteristics. Single crystal X‐ray diffraction showed that all eight complexes had distorted tetrahedral geometries. These complexes exhibited photoluminescence with emission bands peaking from 506 nm to 551 nm and quantum yields up to 0.92 at room temperature. Emission lifetimes varied and showed no direct correlation with quantum yields or wavelengths. Physical manipulation and solvent variations significantly altered their photoluminescent properties. DFT and TD‐DFT calculations revealed that higher arsenic content increased spin‐orbit coupling constants, with iodide complexes performing better than bromide ones due to heavier elements enhancing spin‐orbit coupling. Substituting phosphorus with arsenic significantly affected the luminescence quantum yield and lifetime, demonstrating the heavy‐atom effect of arsenic. The position of arsenic in the ligands critically influenced the photophysical outcomes of the CuX complexes. [ABSTRACT FROM AUTHOR]

The chiral aziridine-containing vicinal iminophenol tridentate ligands (named salazins) are a class of readily prepared chiral ligands from enantiopure aziridines and salicylaldehydes. Their scandium and yttrium triflate complexes show excellent reactivity and enantioselectivities in the catalytic asymmetric aldol condensation of electron-deficient aromatic aldehydes and ketones, including acetone and cycloalkanones. The stereoselectivity is rationalized to the strong π–stacking interaction between aromatic aldehydes and the vicinal iminophenol group in the chiral ligands. [ABSTRACT FROM AUTHOR]

Several strategies are available to design well‐defined multimetallic molecular entities bearing functional ligands. Substoichiometric exchange reactions in the coordination sphere of pre‐existing multinuclear precursors are relatively underexploited in this context. Palladium(II) acetate is not a mononuclear compound in the solid state but rather exists as a trimer, i. e. [Pd3(OAc)6]. Although this material is ubiquitously used to synthesize mononuclear Pd species, it may principally also lend itself to selective exchange of some of the edge‐sharing acetate units in its triangular motif, whilst keeping the overall multinuclear architecture intact. Strikingly, little is known about the controlled manipulation and substoichiometric substitution chemistry of this well‐defined conglomerate. We herein conclusively demonstrate that, for the first time, the targeted exchange of two or four acetate units from the Pd3(acetate)6 platform is possible, thereby installing either one or two new tridentate ligands onto this trinuclear architecture. Follow‐up exchange and substitution chemistry is available without disrupting the multimetallic nature of the core structure. New complexes 2–7 are all conclusively characterized using multinuclear NMR spectroscopy, UV‐vis and IR spectroscopy as well as X‐ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A enantioselective tandem transformation, concerning asymmetric allylic decarboxylative addition and cyclization of N-nosylimines with vinylethylene carbonates (VECs), in the presence of [Rh(C2H4)2Cl]2, chiral sulfoxide-N-olefin tridentate ligand has been developed. The reaction of VECs with various substituted N-nosylimines proceeded smoothly under mild conditions, providing highly functionalized oxazolidine frameworks in good to high yields with good to excellent enantioselectivity. [ABSTRACT FROM AUTHOR]

Nonclassical P(III) centers have attracted much attention in recent years. Incorporating a P(III) center in a rigid bicyclic platform offers a particularly attractive way to invoke significant geometric distortion of the phosphorus atom that may in turn induce unusual reactivity. Although still relatively scarcely explored, phosphorus centers enforced in a non‐C3 symmetry have gained significant traction lately. However, the current scaffolds are based on a relatively limited set of design principles and ligand platforms associated therewith. This work is focussed on the synthesis as well as versatile oxidation, addition and coordination chemistry of a geometrically distorted P(III) species featuring a synthetically modular, nonsymmetric trisamine platform derived from 2‐(methylamino)‐N‐(2‐(methylamino)phenyl)benzenesulfonamide. [ABSTRACT FROM AUTHOR]

The equilibria of the complex formation between the anionic chelate of zinc(II) with the tridentate ligand of 4-(2-pyridylazo)-resorcinol (PAR) and the bulky organic tetrazolium cation of 3-(2-naphtyl)-2,5-diphenyl-2Htetrazolium chloride (TV) in the liquid-liquid extraction system Zn(II)-PAR-TV-H2O-2-methyl-1-propanol was studied by spectrophotometric method. The molar ratio of the reagents was determined by independent methods under the optimum condition for ion-association and for extraction. The validity of Beer's law was checked and some analytical characteristics were calculated. The constants, describing the association process in aqueous phase and the extraction equilibria, were calculated. Based on this, a reaction scheme, a general formula and a structural formula of the complex were suggested. The zinc(II) cation is six coordinated with the tridentate ligand through the following atoms: the azo nitrogen, the pyridine nitrogen and the oxygen atom from the phenolic group, which is in ortho position relative to the azo group, each of them forming two five-membered chelate rings. [ABSTRACT FROM AUTHOR]

Bu çalışmada, üç-dişli bis-benzimidazol piridin türevi ligant (L) ve bu ligantın nötr Zn(II) kompleksi [ZnLCl2] sentezlendi. Elde edilen bu yeni koordinasyon bileşiğinin yapısı aydınlatılarak, elektrokimyasal özellikleri araştırıldı. Moleküllerin yapısal karakterizasyonunda çeşitli spektroskopik yöntemler (FT-IR, 1H NMR, 13C NMR, MALDI-TOF-MS, UV-Vis gibi) kullanıldı. Elektrokimyasal özellikleri ise DMF içerisinde dönüşümlü voltametri (CV) tekniği ve kare dalga voltametrisi kullanılarak araştırıldı. Tarama hızı ve pik akımı arasındaki ilişki kullanılarak kompleksin elektrokimyasal mekanizması aydınlatılmış, kompleksin yarı-tersinir ve difüzyon kontrollü bir davranış sergilediği ortaya konulmuştur. Bu nedenle, kompleksin özellikle de redoks akışlı piller, güneş pilleri ve elektrokataliz gibi alanlarda uygulanabileceği düşünülmektedir.

A enantioselective tandem transformation, concerning asymmetric allylic decarboxylative addition and cyclization of N-nosylimines with vinylethylene carbonates (VECs), in the presence of [Rh(C2H4)2Cl]2, chiral sulfoxide-N-olefin tridentate ligand has been developed. The reaction of VECs with various substituted N-nosylimines proceeded smoothly under mild conditions, providing highly functionalized oxazolidine frameworks in good to high yields with good to excellent enantioselectivity.

Trichloro niobium(V) complexes 3 and 4 with the sulfur- or selenium-bridged [OEO]-type bis(phenolate) ligands (E = S, Se) were synthesized and fully characterized on the basis of their NMR spectroscopic data and X-ray crystallographic analysis. In the crystalline state of 4, the [OSeO]-core of the ligand was coordinated to the niobium center in a fac-fashion. The corresponding tribenzyl niobium(V) complexes 5 and 6 were also prepared by the reactions of 3 and 4 with 3 equivalents of PhCH2MgCl in toluene. The X-ray diffraction analysis of 6 revealed that the distorted six-coordinated niobium center incorporated in the [OSeO]-type ligand took a mer-fashion, and one benzyl ligand was coordinated to the niobium center by η2-fashion. Complexes 5 and 6 were tested for the phenylacetylene polymerization that produced poly(phenylacetylene)s (PPAs), oligomers, and triphenylbenzenes (TPBs) depending on the chalcogen atom in the [OEO]-type ligand. [ABSTRACT FROM AUTHOR]

The isomerism of zinc complex [Zn(L)2]2+ with tridentate ligand L having acetamide and pyridine groups on each side of the central amino- nitrogen atom has been investigated by DFT calculations, liquid state NMR and single-crystal X-ray diffraction. DFT was used for obtaining the ensembles of low-energy conformers of L and [Zn(L)2]2+ and for the calculation of NMR parameters for all conformers. For all generated conformers of L and [Zn(L)2]2+, the Mean Absolute Error [MAE(conf)] was tested as a structural quality parameter and compared with MAE(Bolz) for Boltzmann weighted ensembles. The most populated conformers had MAE(conf) values below 0.1 and 1 ppm for 1H shifts and 13C shifts, respectively. For the [Zn(L)2]2+ complex, the mer- C2 symmetric isomer was the most stable, in accordance with the X-ray structure of [Zn(L)2]2[SiF6][BF4]2. The cancellation of the magnetic equivalence of some nuclei valid for free L, when coordinated to the Zn2+ cation, was theoretically explained by the correct averaging of NMR parameters in the calculation procedure. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • A series of novel CDK9 inhibitor with tridentate ligand were designed and synthesized. • The unique tridentate ligand structure endows better CDK9 inhibition selectivity compared to other CDK subtypes. • Lead candidate Z4-7a showed effective proliferation inhibition in HCT116 cells with acceptable PK properties. • Z4-7a induced apoptosis effects on HCT116 cells. Cyclin-dependent kinase 9 (CDK9) plays a role in transcriptional regulation, which had become an attractive target for discovery of antitumor agent. In this work, beyond traditional CDK9 inhibitor with bidentate ligands in ATP binding domain, a series of novel CDK9 inhibitor with tridentate ligand were designed and synthesized. Surprisingly, this unique tridentate ligand structure endows better CDK9 inhibition selectivity compared to other CDK subtypes, and the lead candidate compound Z4-7a showed effective proliferation inhibition in HCT116 cells with acceptable pharmacokinetic properties. Research on the mechanism indicated that Z4-7a could induce apoptosis in the HCT116 cell line by inhibiting phosphorylation of RNA polymerase II at Ser2, which resulted in the inhibition of apoptosis-related genes and proteins expression. In brief, introduction of tridentate ligand might work as a promising strategy for the development of novel selective CDK9 inhibitor. [ABSTRACT FROM AUTHOR]

The molecular and crystal structures of two ruthenium(II) complexes, viz. cis-aqua[2,6-bis(1,8-naphthyridin-2-yl)pyridine-λ³N,N',N"](thiocyanato-λN)-(triphenylphosphine-λP)ruthenium(II) hexafluoridophosphate-acetone-water (1/0.5/1), [Ru(NCS)(C21H13N5)(C18H15P)(H2O)]PF6λ0.5C3H6OλH2O (I) and trans-[2,6-bis(1,8-naphthyridin-2-yl)pyridine-λ³'N,N',N"]bis(pyridine-λN)(thiocyanato-λN)ruthenium(II) thiocyanate, [Ru(NCS)(C21H13N5)(C5H5N)2]NCS (II), with an N-coordinating thiocyanato group and a tridentate polypyridyl supporting ligand, are reported. The RuII atom in each of the cationic complexes adopts a distorted octahedral coordination sphere, defined by an N atom of the thiocyanato ligand, three N atoms from the tridentate polypyridyl ligand, and an O and P atom in (I) or two pyridine-N atoms in (II) derived from monodentate ligands. The thiocyanato ligand in (I) coordinates in an axial manner to the {Rudnp} unit [dnp = 2,6-bis(1,8-naphthyridin-2-yl)pyridine], whereas it coordinates in an equatorial manner in (II). In the crystal structure of compound (I), intramolecular C--H...O, C--H...N and O--H...N hydrogen bonds as well as π-π contacts are present, in addition to intermolecular C--H...F, C--H...O and O--H...O hydrogen bonds. In the crystal structure of compound (II), intramolecular C--H...N hydrogen bonds are observed along with intermolecular C--H...N and C--H...S hydrogen bonds as well as a π-π interaction. [ABSTRACT FROM AUTHOR]

A square-planar Cu(II) complex [Cu(L)Cl], 1, with sterically constrained tridentate phenol-based ligand (HL= N,N,N′-trimethyl-N′-(2-hydroxy-3,5-di-tert-butylbenzyl)-ethylenediamine) with N, N, O donor sites has been synthesized. The complex is characterized by single crystal X-ray diffraction study as well as other spectroscopic techniques. The reported complex crystallizes in monoclinic space group C2/c with a = 30.248(6), b = 13.750(3) and c = 11.410(2) Å with β = 110.232(2)°. The Cu(II) ion adopts a square planar environment in this complex. Electrochemical study of the complex 1 gives quasi-reversible reductive response at E1/2 ≈ −0.5 V due to the reduction of the Cu(II) center along with a reversible oxidation peak at E1/2 ≈ 0.75 V. The oxidation peak arises due to the ligand-based oxidation of phenolate group to phenoxyl radical in the complex. The Cu(II) complex exhibits catechol oxidase activity in methanol as observed by the UV–vis spectroscopy of the aerial oxidation of 3,5-DTBC to 3,5-DTBQ and the reaction proceeds via the formation of ligand phenoxyl radical. The turnover number for complex 1 is 2560 h−1. [ABSTRACT FROM AUTHOR]

In this research, the tridentate Schiff base ligand N2O was prepared and then the 1D Cu(II) ‎coordination ‎polymer was synthesized. The ligand and polymer were characterized via analytical and ‎spectral methods. The ‎crystal structure of polymer was determined by single crystal X-ray diffraction ‎method. It was exhibited that ‎the Cu(II) ion was surrounded by tridentate Schiff base ligand and ‎acetate ion, produced distorted octahedral ‎geometry. Two nitrogen atoms( one aminic ‎nitrogen atom and one iminic nitrogen atom) and one phenolic ‎oxygen atom from tridentate Schiff ‎base ligand and two oxygen atoms of acetate ion coordinated to the Cu(II) ‎ion. One of the oxygen ‎atoms was simultaneously coordinated to two Cu(II) ions and caused the formation of ‎the linear ‎coordination polymer. The antibacterial activity of the ligand and coordination polymer was ‎‎investigated against the Klebsiella pneumoniae‎‏‎,‎‏ ‏‏‎ Salmonella enterica bacteria and the results showed ‎that the ‎ligand was exhibited higher activity than the polymer. ‎

In the title compound, C24H15Cl2N3O2, one quinoline ring system is essentially planar and the other is slightly bent. An intramolecular O—H...N hydrogen bond involving the hydroxy group and a pyridine N atom forms an S(5) ring motif. In the crystal, two molecules are associated into an inversion dimer with two R22(7) ring motifs through intermolecular O—H...N and O—H...O hydrogen bonds. The dimers are further linked by an intermolecular C—H...O hydrogen bond and four C—H...π interactions, forming a two-dimensional network parallel to (001).

Trichloro niobium(V) complexes 3 and 4 with the sulfur- or selenium-bridged [OEO]-type bis(phenolate) ligands (E = S, Se) were synthesized and fully characterized on the basis of their NMR spectroscopic data and X-ray crystallographic analysis. In the crystalline state of 4, the [OSeO]-core of the ligand was coordinated to the niobium center in a fac-fashion. The corresponding tribenzyl niobium(V) complexes 5 and 6 were also prepared by the reactions of 3 and 4 with 3 equivalents of PhCH2MgCl in toluene. The X-ray diffraction analysis of 6 revealed that the distorted six-coordinated niobium center incorporated in the [OSeO]-type ligand took a mer-fashion, and one benzyl ligand was coordinated to the niobium center by η2-fashion. Complexes 5 and 6 were tested for the phenylacetylene polymerization that produced poly(phenylacetylene)s (PPAs), oligomers, and triphenylbenzenes (TPBs) depending on the chalcogen atom in the [OEO]-type ligand.

The catalytic asymmetric synthesis of P‐chiral phosphorus compounds is an important way to construct P‐chiral ligands. Herein, we report a new strategy that adopts the pyridinyl moiety as the coordinating group in the cobalt‐catalysed asymmetric nucleophilic addition/alkylation of secondary phosphine oxides. A series of tertiary phosphine oxides were generated with up to 99 % yield and 99.5 % ee, and with broad functional‐group tolerance. Mechanistic studies reveal that (R)‐secondary phosphine oxides preferentially interact with the cobalt catalysts to produce P‐stereogenic compounds. [ABSTRACT FROM AUTHOR]

A new Zn(II) coordination complex based on the tridentate ONO Schiff base 2-(((2-methoxyphenyl)imino)methyl)phenolate ligand was synthesized and characterized structurally by using FT-IR, 1H NMR, 13C{1H}NMR, UV−Vis and photoluminescence spectroscopies, elemental analysis and single crystal X-ray crystallography (CIF file CCDC no. 2027332). The molecular structure as well as its supramolecular features was studied using structural, Hirshfeld surface analyses as well as computational studies. The supramolecular arrangement of this coordination complex is directed by a series of hydrogen bonding interactions, including O−H···O, C−H···Br and C−H···π. The C−H···π energies in this compound calculated to be in the range of 5.79–7.99 Å. The compound is also successfully synthesized in three different concentrations by ultrasonic irradiation. The product was characterized by different techniques and the morphology was analyzed using field-emission scanning electron microscopy. The comparison between samples synthesized using ultrasonic irradiation demonstrated that lower concentrations of initial reagents decreased plate size and increased the homogenization of particle size distribution. [ABSTRACT FROM AUTHOR]

The isomerism of zinc complex [Zn(L)2]2+ with tridentate ligand L having acetamide and pyridine groups on each side of the central amino- nitrogen atom has been investigated by DFT calculations, liquid state NMR and single-crystal X-ray diffraction. DFT was used for obtaining the ensembles of low-energy conformers of L and [Zn(L)2]2+ and for the calculation of NMR parameters for all conformers. For all generated conformers of L and [Zn(L)2]2+, the Mean Absolute Error [MAE(conf)] was tested as a structural quality parameter and compared with MAE(Bolz) for Boltzmann weighted ensembles. The most populated conformers had MAE(conf) values below 0.1 and 1 ppm for 1H shifts and 13C shifts, respectively. For the [Zn(L)2]2+ complex, the mer- C2 symmetric isomer was the most stable, in accordance with the X-ray structure of [Zn(L)2]2[SiF6][BF4]2. The cancellation of the magnetic equivalence of some nuclei valid for free L, when coordinated to the Zn2+ cation, was theoretically explained by the correct averaging of NMR parameters in the calculation procedure.

Ligand-controlled divergent regioselectivity in Pd-catalyzed alkoxycarbonylation of alkenes. [Display omitted] • Synthesis of pinwheel-like tridentate phosphines. • Ligand-controlled divergent regioselectivity in Pd-catalyzed alkoxycarbonylation of alkenes. • Flexible tridentate phosphine in charge of anti -Markovnikov's alkoxycarbonylation of alkenes. • Rigid tridentate phosphine in charge of Markovnikov's alkoxycarbonylation of alkenes. The elaborate control of regioselectivity regulated by the involved ligands with specific structural skeleton and compositions is always demanded in alkoxycarbonylation of alkenes. Herein, a series of pinwheel-like tridentate phosphine ligands with rotatable flexibility (L3) or hard rigidity (L5–L7) were synthesized and characterized for the first time, in which the incorporated three PPh 2 -fragments are located at meta-positions of phenyl groups. It was proved that the tridentate phosphine of L3 with the flexible configuration favorably corresponded to the linear regioselectivity with l/b ratio of 98/2, whereas L7 with the rigid configuration absolutely did favor to the branched regioselectivity with l/b ratio of 1/99. The presence of the three PPh 2 -frgaments in L3 did contribute to the remarkable performance of L3 -Pd(TFA) 2 system in terms of activity, linear regioselectivity and stability, subjected to 10-run recycling uses in anti -Markovnikov's methoxycarbonylation of styrene without activity loss and Pd-black precipitation. In comparison, although the optimal L7 -Pd(MeCN) 2 Cl 2 system could catalyze Markovnikov's alkoxycarbonylation of alkenes to afford the branched esters with excellent regioselectivity in the fresh use, its stability was too poor to support the recycling experiments. L3 -Pd(TFA) 2 and L7 -Pd(MeCN) 2 Cl 2 catalytic systems were both applicable to a wide range of substrates in alkoxycarbonylation of alkenes to afford the target esters in the isolated yields of 41–91 %, with the well maintained divergent regioselectivity. [ABSTRACT FROM AUTHOR]

Abstract A photoactivatable ruthenium(II) carbonyl complex mer,cis‐[Ru(II)Cl(BisQ)(CO)2]PF6 2 was prepared using a tridentate bisquinoline ligand (BisQ=(2,6‐diquinolin‐2‐yl)pyridin). Compound 2 was thoroughly characterized by standard analytical methods and single crystal X‐ray diffraction. The crystal structure of the complex cation reveals a distorted octahedral geometry. The decarbonylation upon exposure to 350 and 420 nm light was monitored by UV/VIS absorbance and Fourier transform infrared spectroscopies in acetonitrile and 1 % (v/v) DMSO in water, respectively. The kinetic of the photodecarbonylation has been elucidated by multivariate curve resolution alternating least‐squares analysis. The stepwise decarbonylation follows a serial mechanism. The first decarbonylation occurs very quickly whereas the second decarbonylation step proceeds more slowly. Moreover, the second rate constant is lower in 1 % (v/v) DMSO in water than in acetonitrile. In comparison to 350 nm irradiation, exposure to 420 nm light in acetonitrile results in a lower second rate constant.

The title complex, [Pd(NO3)(C15H11N3)]NO3, comprises a cationic PdII complex and a nitrate anion. In the complex, the PdII cation is four-coordinated in a distorted square-planar coordination geometry defined by the three N atoms of the tridentate 2,2′:6′,2′′-terpyridine ligand and one O atom from the NO3− anion. In the crystal, the complex molecules are stacked in columns along the a axis being connected by π–π stacking [closest inter-centroid separation between pyridyl rings = 3.878 (3) Å]. The connections between columns and anions to sustain a three-dimensional architecture are C—H...O hydrogen bonds.

A square-planar Cu(II) complex [Cu(L)Cl], 1, with sterically constrained tridentate phenol-based ligand (HL= N,N,N′-trimethyl-N′-(2-hydroxy-3,5-di-tert-butylbenzyl)-ethylenediamine) with N, N, O donor sites has been synthesized. The complex is characterized by single crystal X-ray diffraction study as well as other spectroscopic techniques. The reported complex crystallizes in monoclinic space group C2/c with a = 30.248(6), b = 13.750(3) and c = 11.410(2) Å with β = 110.232(2)°. The Cu(II) ion adopts a square planar environment in this complex. Electrochemical study of the complex 1 gives quasi-reversible reductive response at E1/2 ≈ −0.5 V due to the reduction of the Cu(II) center along with a reversible oxidation peak at E1/2 ≈ 0.75 V. The oxidation peak arises due to the ligand-based oxidation of phenolate group to phenoxyl radical in the complex. The Cu(II) complex exhibits catechol oxidase activity in methanol as observed by the UV–vis spectroscopy of the aerial oxidation of 3,5-DTBC to 3,5-DTBQ and the reaction proceeds via the formation of ligand phenoxyl radical. The turnover number for complex 1 is 2560 h−1.

A series of cationic rare‐earth aryloxide complexes, i.e., [LREOAr']+[B(C6F5)4]– (L = CH3C(NAr)CHC(CH3)(NCH(R)CH2PPh2); RE = Y, Lu; Ar' =2,6‐tBu2‐C6H3, 2,6‐(PhCMe2)2‐4‐Me‐C6H2; Ar = 2,6‐iPr2‐C6H3, 2,6‐(Ph2CH)2‐4‐iPr‐C6H2; R = H, CH3, iPr, Ph), were prepared and applied to the Lewis pair polymerization of methyl methacrylate (MMA). The stereoregularity of the resulting PMMA was significantly affected by the R substituent on the pendant arm of the tridentate NNP ligand, and was found to increase with increase in the steric hindrance of R. When using a Ph group as R, the Y complex produced a highly isotactic polymer with an mm value of 95% and a Tg of 54.6 oC. In contrast, the steric hindrance of the Ar and Ar' groups had no effect on the tacticity of the resulting polymer, presumably because these two substituents were situated such that they pointed outward from the cyclic intermediates. Kinetics studies demonstrated that the polymerization was a first‐order process with regard to the monomer concentration prior to catalyst deactivation. End group analysis indicated that the polymerization was accompanied by two possibly competing chain‐termination side reactions that proceeded via intramolecular backbiting cyclization. [ABSTRACT FROM AUTHOR]

The title compound, C14H12N2O4, is nearly planar with a dihedral angle between the aromatic rings of 1.41 (8)°. The phenolic O atom is deprotonated and the N atom of the azomethine unit carries the proton, thereby forming an intramolecular N—H...O hydrogen bond. In the crystal, the molecules form inversion dimers via pairwise O—H...O hydrogen bonds.

The title compound, [NiBr(C25H29N2O)], contains an NiII atom with a slightly distorted square-planar coordination environment defined by one O and two N atoms from the 2-{[(8-aminonaphthalen-1-yl)imino]methyl}-4,6-di-tert-butylphenolate ligand and a bromide anion. The Ni—O and Ni—N bond lengths are slightly longer than those observed in the phenyl backbone counterpart, which can be attributed to the larger steric hindrance of the naphthyl group in the structure of the title compound. The molecule as a whole is substantially distorted, with both the planar naphthalene-1,8-diamine and imino–methyl–phenolate substitutents rotated against the NiN2OBr plane by 38.92 (7) and 37.22 (8)°, respectively, giving the molecule a twisted appearance. N—H...Br hydrogen bonds and N—H...C(π) contacts connect the molecules into dimers, and additional C—H...Br contacts, C—H...π interactions, and an offset stacking interaction between naphthyl units interconnect these dimers into a three-dimensional network.

A tridentate bisbenzimidazole‐pyridine ligand (L‐C5) with two pentyl side‐units and its metal complexes with Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ metal ions were synthesized and characterized. The structures of the ligand (L‐C5) and its five coordinate [Mn(L‐C5)Cl2] were elucidated by single crystal X‐ray diffraction studies. The absorption and photoluminescence properties of the compounds were studied in solution media. The ligand is highly fluorescent, and binding of the metal ions to the ligand has caused significant changes in the emission band (shift or quenching). Moreover, the effect of aggregation on UV–Vis. absorption and emission properties was examined in MeOH‐water mixtures. The ligand was found to show aggregation‐induced quenching in the MeOH‐water mixture. The ligand was also screened for its colorimetric and fluorometric sensing ability of several metal ions [Na+, K+, Mg2+, Al3+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Hg2+, Pb2+]. The ligand showed selective sensing ability towards Zn2+, and the limit of detection was calculated as 3.09 × 10−7m. The ligand also showed a distinguishable color change in the presence of Fe2+ under daylight. [ABSTRACT FROM AUTHOR]

Two dinuclear complexes of [LCu(Cl)(μ-Cl)CuCl3][LCu(Cl)(μ-Cl)CuL(H2O)]Cl, 1 and [LCu(Br)(μ-Br)]2Br, 2, with a tridentate ligand of 3-((pyridin-2-ylmethyl)amino)propanamide, L, were prepared and characterized by physicochemical (elemental analyses, molar conductance measurements, thermogravimetry) and spectroscopic (IR, UV–vis) data. The crystal structures of compounds have been identified by single-crystal X-ray diffraction analyses and showed that the tridentate ligand L functions as an N2O-donor via the nitrogen atoms of the secondary amine and pyridyl moieties together with the oxygen atom of the amide group. The structural geometry about the copper(II) ions is a distorted square pyramid. The compounds are chromotropic and their reversible chromotropism was investigated by utilizing spectral analysis. The halochromism was due to structural change and followed by ionization of the coordinated water molecules and deprotonation of the secondary amine moiety. It was discovered that the solvatochromism of the compounds arisen from the structural change followed by the solvation of the vacant sites of the complexes. The compounds demonstrated ionochromism and sensitivity and selectivity towards CN− and N3− anions in the presence of other pseudo-halide anions. [ABSTRACT FROM AUTHOR]

In the title compound, C24H15Cl2N3O2, one quinoline ring system is essentially planar and the other is slightly bent. An intramolecular O—HN hydrogen bond involving the hydroxy group and a pyridine N atom forms an S(5) ring motif. In the crystal, two molecules are associated into an inversion dimer with two R2 ² (7) ring motifs through intermolecular O—H. . . N and O—H. . .O hydrogen bonds. The dimers are further linked by an intermolecular C—H. . .O hydrogen bond and four C—H . . .&#960:interactions, forming a two-dimensional network parallel to (001). [ABSTRACT FROM AUTHOR]

A thioether unsymmetrical N2S donor Schiff base ligand, N-2-((2-nitrophenyl)thio)phenyl)-1-(pyrrole-2-yl)methanimine (HL) and its five complexes [NiL2], [CuL2], [ZnHL(H2O)2(OAc)2], [CdHL(H2O)2(OAc)2]·2H2O and [MnHL(H2O)2(OAc)2]·2H2O were synthesized. The ligand and metal complexes were characterized by spectroscopic methods (FT-IR, 1H and 13C NMR, UV–Vis), elemental analyses, mass spectrometry, and conductance measurements. Of these complexes, [NiL2] was structurally characterized by single-crystal X-ray crystallography. In this complex, two ligands function as monobasic N2S tridentate and coordinate through pyrrole-N, thioether-S, and azomethine-N, and the nickel(II) is in distorted octahedral environments. [ABSTRACT FROM AUTHOR]

A series of Mn(I) catalysts containing imidazole-based chiral PNN tridentate ligands with controllable 'side arm' groups have been established, enabling the inexpensive base-promoted asymmetric hydrogenation of simple ketones with outstanding activities (up to 8200 TON) and good enantioselectivities (up to 88.5% ee). This protocol features wide substrate scope and functional group tolerance, thereby providing easy access to a key intermediate of crizotinib. [ABSTRACT FROM AUTHOR]

It is demonstrated here that tridentate imine ligands can control the nuclearity of copper(II) complexes based on the donor atoms present in the ligand. The N,N′,N′′-donating imine ligand led to a mononuclear compound, namely dichlorido[N,N-dimethyl-N′-(pyridin-2-ylmethylidene)ethane-1,2-diamine]copper(II) monohydrate, [CuCl2(C10H15N3)]·H2O, 1, while the N,N′,O-donating imine ligand produced a binuclear metal complex, namely μ2-chlorido-dichlorido(μ2-2-{[2-(dimethylamino)ethyl]iminomethyl}phenolato)(N,N-dimethylethylenediamine)dicopper(II) 0.11-hydrate, [Cu2(C11H15N2O)Cl3(C4H12N2)]·0.11H2O, 2. The structure of 2 is a remarkable example of a binuclear copper(II) complex containing a single substituted 2-iminomethylphenolate ligand that has two copper(II) sites in square-pyramidal coordination.

A carboxyamine functionalized tridentate ligand in combination with three different carboxylate bridging groups (RCO2−; R=CH3, C2H5 and CF3) has been utilized to prepare tetra‐ and pentanuclear nickel(II) complexes, [Ni4(L)2(μ3‐OCH3)2(μ1,1‐O2CCH3)2(μ1,3‐O2CCH3)2(CH3OH)2] (1), [Ni4(L)2(μ3‐OCH3)2(μ1,1‐O2CC2H5)2(μ1,3‐O2CC2H5)2(CH3OH)2] (2) and [Ni5(L)4(μ3‐OH)2(μ1,3‐O2CCF3)2]Br2⋅3H2O (3) (HL=3‐[(2‐pyridylmethyl)‐amino]‐propionic acid). The complexes have been characterized using several techniques such as elemental analysis, solution electrical conductivity, FTIR and UV‐Vis spectroscopy, and low temperature magnetic measurements. While complex 1 and 3 were further characterized using single crystal X‐ray diffraction, molecular structure of complex 2 has been optimized using DFT calculation. Whereas the acetate/propionate groups deliver Ni4 cluster, the trifluoroacetate group provides Ni5 assembly. Molecular structures of complexes 1 and 2 comprise a central [Ni4O6] core that could be described as a distorted face‐shared dicubane with two missing vertices. On the other hand, the [Ni5(μ3‐OH)2(μ1,3‐O2CCF3)2]6+ structural core of complex 3 contains five coplanar nickel(II) ions in a rectangular organization. Variable‐temperature magnetic susceptibility studies reveal the interesting magnetic properties of complexes 1 and 3. While complex 1 shows both ferro‐ and antiferromagnetic interactions with J1=−1.10 cm−1, J2=+2.40 cm−1 and J3=−0.65 cm−1, complex 3 exhibits only ferromagnetic interactions with J1=+2.0 cm−1 and J2=+1.0 cm−1. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new type of tridentate chiral spiro aminophosphine--oxazoline ligands (SpiroOAP) have been synthesized through four steps. The SpiroOAP ligands are highly efficient for the asymmetric hydrogenation of a-keto amides, providing a variety of synthetically useful a-hydroxy amides with excellent enantioselectivity (up to 98% ee) and turnover numbers (up to 10,000). [ABSTRACT FROM AUTHOR]

A photoactivatable ruthenium(II) carbonyl complex mer,cis‐[Ru(II)Cl(BisQ)(CO)2]PF62 was prepared using a tridentate bisquinoline ligand (BisQ=(2,6‐diquinolin‐2‐yl)pyridin). Compound 2 was thoroughly characterized by standard analytical methods and single crystal X‐ray diffraction. The crystal structure of the complex cation reveals a distorted octahedral geometry. The decarbonylation upon exposure to 350 and 420 nm light was monitored by UV/VIS absorbance and Fourier transform infrared spectroscopies in acetonitrile and 1 % (v/v) DMSO in water, respectively. The kinetic of the photodecarbonylation has been elucidated by multivariate curve resolution alternating least‐squares analysis. The stepwise decarbonylation follows a serial mechanism. The first decarbonylation occurs very quickly whereas the second decarbonylation step proceeds more slowly. Moreover, the second rate constant is lower in 1 % (v/v) DMSO in water than in acetonitrile. In comparison to 350 nm irradiation, exposure to 420 nm light in acetonitrile results in a lower second rate constant. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Six new Mo(VI) oxo complexes have been synthesized and characterized. • All complexes are based on aminoalcohol phenolate ligands. • Three complexes are mononuclear, two are dinuclear and one is trinuclear. • All complexes catalyse epoxidation of olefins by H 2 O 2 or t BuOOH. Abstract Reaction of the tridentate aminoalcohol phenol ligands 2,4-di- tert -butyl-6-(((2 hydroxyethyl)(methyl)amino)methyl)phenol (H 2 L1) and 2,4-di- tert -butyl-6-(((1-hydroxybutan-2-yl)amino)methyl)phenol (H 2 L2) with [MoO 2 (acac) 2 ] in methanol solutions resulted in the formation of [MoO 2 (L1)(MeOH)] (1) and [MoO 2 (L2)(MeOH)] (3), respectively. In contrast, the analogous reactions in acetonitrile afforded the dinuclear complexes [Mo 2 O 2 (μ-O) 2 (L1) 2 ] (2) and [Mo 2 O 2 (μ-O) 2 (L2) 2 ] (4). The corresponding reactions with the potentially tetradentate ligand 3-((3,5-di- tert -butyl-2-hydroxybenzyl)(methyl)amino)propane-1,2-diol (H 3 L3) led to the formation of the mononuclear complex [MoO 2 (L3)(MeOH)] (5) in methanol while in acetonitrile solution a trinuclear structure [Mo 3 O 3 (μ-O) 3 (L3) 3 ] (6) was obtained. In both cases, the ligand moiety L3 coordinated in a tridentate fashion. The catalytic activities of complexes 1 – 6 in epoxidation of five different olefins, S1-5 , with tert -butyl hydroperoxide and hydrogen peroxide were studied. The catalytic activities were found to be moderate to good for the reaction of substrate cis -cyclooctene S1 , while all complexes were less active in the epoxidation of the more challenging substrates S2-5. The molecular structures of 1 , 2 , 4 and 6 were determined by single crystal X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

• The ligand HBH has been used to synthesize Co(II), Ni(II), Cu(II) and Zn(II) complexes using respective chloride metal salts. • Ligand and respective metals has been characterized using varied spectral methods and thermal analysis along with SEM & EDX techniques. • The electrochemical property of the Co(II) complex was studied by cyclic voltammeter • using modified GCE. • Co(II) metal in conjunction with ligand was successfully modified and used as sensor for individual and simultaneous detection of heavy metals (Pb2+, Cd2+ & Hg2+) through CV and LSV technique. • The antimicrobial, antioxidant, antiobesity and cytotoxicity studies of the ligand and metal complexes were performed. • The molecular docking of the metal complexes on cancer receptor PDB ID: 2A91 and microbial receptor PDB ID: 2MBR was conducted. This study endorses the combination of experimental and pharmacological studies of 3d-metal chelates (Co(II), Ni(II), Cu(II) & Zn(II)) of novel ligand (E)-2-hydroxy-N'-(2-oxoindolin-3-ylidene)benzohydrazide (HBH) bearing isatin moiety. An array of physical and spectroscopic methods were employed to characterize the synthesized ligand and its 3d-metal complexes. In accordance with the spectroscopic methods, all the metal-coordinated compounds exhibited tridentate coordination and octahedral geometry. Further, a modified cobalt(II) metal complex carbon electrode with MWCNTs served as a sensor to identify three most noxious heavy metal ions (Pb2+, Hg2+, Cd2+) individually and simultaneously using CV and LSV methods. Generally, the proposed sensor was reliable, repeatable with high sensitivity ensuring its practical implementations in real samples with agreeable results. Also, an important aspect of this study was the exploration of the antimicrobial, antioxidant, antiobesity and anticancer properties of ligand HBH and its 3d-metal complexes. The results from the biological screening exposed the fact that the coordinated compounds demonstrated significantly higher pharmacological activities than their ligand. Additionally, molecular docking study was undertaken for antimicrobial and anticancer receptors to determine binding modes of ligand and its metal chelates. [Display omitted] [ABSTRACT FROM AUTHOR]

Synthesis, characterization, antimalarial, antioxidant and antimicrobial activities of four newly synthesized hydrazone ligands and their diorganotin(IV) metal complexes. [Display omitted] • This research work emphasizes study of hydrazone ligands and their diorganotin(IV) complexes. • The compounds were characterised by physical and spectral investigations. • The biological studies such as antimalarial, antioxidant and antimicrobial were carried out and further supported by in silico ADME studies. • The complexes (16,20) were most active against antimalarial and antioxidant. • Complexes (8, 12) were most potent against antimicrobial. Inspired by the role of organotin(IV) compounds as potential pharmaceutical agents, we have synthesized a series of new diorganotin(IV) complexes (5–20) of hydrazone ligands (1–4) derived from 2-chlorophenoxyacetic hydrazide and salicylaldehyde derivatives. Numerous techniques such as FT-IR, UV–Vis, (1H, 13C, 119Sn) NMR, mass spectrometry, powder XRD, SEM, EDAX, TGA and molar conductance were used to elucidate the structure of the synthesized compounds. These techniques ascertain that the hydrazone ligands coupled with diorganotin(IV) in a tridentate manner via imine nitrogen, phenolic oxygen atom and deprotonated hydroxyl group generating pentacoordinated geometry of the complexes. The low molar conductance values of synthesized compounds indicated their non-electrolytic nature. SnO 2 was the final product formed as a result of the thermal breakdown of complexes which suggested the thermal stability of the complexes up to about 176°C. In vitro antimalarial (P.falciparum) activity was performed using microassay protocol which advocated for the higher potency of complexes 16, 20 (IC 50 = 0.62–0.67 µM). The antioxidant activity also supported the results of antimalarial data suggesting 16, 20 complexes as active compounds. In vitro, the antimicrobial potential of the compounds has been tested against six pathogens including four bacterial and two fungal strains by serial dilution assay taking ciprofloxacin and fluconazole as reference drugs. Among the synthesized compounds, complexes 8 and 12 (MIC value = 0.0048, 0.0045 µmol/mL) exhibited superior activity. Additionally, the compounds were subjected to in silico ADME analysis suggesting that the compounds can be employed as orally active drugs. [ABSTRACT FROM AUTHOR]

The asymmetric unit in the title compound, {[Ag(C12H12N2S)]·NO3}n or {[AgL]·NO3}n, L = bis(pyridin-3-ylmethyl)sulfane, consists of an AgI cation bound to a pyridine N atom of an L ligand and an NO3− anion that is disordered over two orientations in an 0.570 (17):0.430 (17) occupancy ratio. Each AgI cation is coordinated by two pyridine N atoms from adjacent L ligands to form an infinite zigzag chain along [110]. In addition, each AgI ion binds to an S donor from a third L ligand in an adjacent parallel chain, resulting in the formation of a twisted-ribbon type of double-stranded chain propagating along the [110] or [1-10] directions. The AgI atom is displaced out of the trigonal N2S coordination plane by 0.371 (3) Å because of interactions between the AgI cation and O atoms of the disordered nitrate anions. Intermolecular π–π stacking interactions [centroid-to-centroid distance = 3.824 (3) Å] occur between one pair of corresponding pyridine rings in the double-stranded chain. In the crystal, the double-stranded chains are alternately stacked along the c axis with alternate stacks linked by intermolecular π–π stacking interactions [centroid-to-centroid distance = 3.849 (3) Å], generating a three-dimensional supramolecular architecture. Weak intermolecular C—H...O hydrogen bonds between the polymer chains and the O atoms of the nitrate anions also occur.

Tridentate ligands are simple low-cost pincers, easy to synthetize, and able to guarantee stability to the derived complexes. On the other hand, due to its unique mix of structural and optical properties, zinc(II) ion is an excellent candidate to modulate the emission pattern as desired. The present work is an overview of selected articles about zinc(II) complexes showing a tuned fluorescence response with respect to their tridentate ligands. A classification of the tridentate pincers was carried out according to the binding donor atom groups, specifically nitrogen, oxygen, and sulfur donor atoms, and depending on the structure obtained upon coordination. Fluorescence properties of the ligands and the related complexes were compared and discussed both in solution and in the solid state, keeping an eye on possible applications.

In the title compound, [Ni(C11H15N2S)(C7H7OS)] or [Ni(NNImS)(4-OCH3PhS)] (NNImS = 2-{[2-(dimethylamino)ethyl]iminomethyl}benzenethiolato), the NiII cation is coordinated by a tridentate NNImS ligand and a monodentate thiolate ligand giving an N2S2 coordination set defining an almost square-planar environment. The Ni—Namine bond in the coordination plane is approximately 0.1 Å longer than the Ni—Nimine bond.