Octahedral Configuration Research Articles

A new symmetrical nickel(II) complex with isothiocyanate coordination: synthesis, crystal structure, Hirshfeld surface analysis, DFT calculation and antibacterial activities

The metal salts KSCN, Ni(CH3COO)2·4H2O, and auxiliary ligand pyridine were added respectively to the salamo-like ligand H2L, and it is expected that the Ni(II) complex coordinated by H2L will be obtained. X-ray analysis of the obtained blue bulk single crystal revealed that the ligand H2L did not participate in the coordination, and a mononuclear Ni(II) complex [Ni(Py)4(NCS)2] contained four coordinated pyridine molecules was unexpectedly obtained, and characterized by IR, UV-Visible spectroscopy, and X-ray diffraction. The Ni(II) atom was surrounded by six N atoms, formed a slightly distorted octahedral geometry configuration. Hirshfeld surfaces analyses were performed to determine the various interactions presented in the molecule. DFT calculations were also conducted. In antimicrobial tests, the Ni(II) complex exhibited better inhibition of Escherichia coli relative to Staphylococcus aureus.

Phase transition dynamics in one-dimensional halide perovskite crystals

Abstract

A family of 2p-3d complexes based on 4,5-dimethyltriazole nitronyl nitroxide radical: synthesis, structure, and magnetic properties

Three 2p-3d complexes were successfully synthesized by using 4,5-dimethyltriazole nitronyl nitroxide radical. All of the complexes with the same formula of [M(hfac)2(4,5-di-Me-3-NIT-trz)2] [M = Co(II) 1, Ni(II) 2, Cu(II) 3; 4,5-di-Me-3-NIT-trz = 2-[3-(4,5-dimethyl-l,2,4-triazolyl)]-4,4,5,5-tetramethylimida-zoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetone] are characterized by X-ray analysis, and their magnetic properties were studied in detail. The metal ions in 1–3 are all in distorted octahedral configuration with four oxygen atoms from two bidentate hfac– ligands, and two triazole N atoms from two different 4,5-di-Me-3-NIT-trz ligands. The magnetic behaviors for 1–3 indicate that the metal ions and the radicals are antiferromagnetically coupled (JCo-rad = −7.11 cm−1, for 1; JNi-rad = −1.63 cm−1, for 2; JCu-rad = −8.71 cm−1, for 3). In addition, ferromagnetic coupling exists between the uncoordinated NO radicals in complex 1, while the magnetic reactions Jrad-rad are antiferromagnetic in complexes 2–3.

Mn-O Covalency Governs the Intrinsic Activity of Co-Mn Spinel Oxides for Boosted Peroxymonosulfate Activation.

Transition metal (TM)-based bimetallic spinel oxides can efficiently activate peroxymonosulfate (PMS) presumably attributed to enhanced electron transfer between TMs, but the existing model cannot fully explain the efficient TM redox cycling. Here, we discover a critical role of TM-O covalency in governing the intrinsic catalytic activity of Co3-x Mnx O4 spinel oxides. Experimental and theoretical analysis reveals that the Co sites significantly raises the Mn valence and enlarges Mn-O covalency in octahedral configuration, thereby lowering the charge transfer energy to favor MnOh -PMS interaction. With appropriate MnIV /MnIII ratio to balance PMS adsorption and MnIV reduction, the Co1.1 Mn1.9 O4 exhibits remarkable catalytic activities for PMS activation and pollutant degradation, outperforming all the reported TM spinel oxides. The improved understandings on the origins of spinel oxides activity for PMS activation may inspire the development of more active and robust metal oxide catalysts.

Mn−O Covalency Governs the Intrinsic Activity of Co‐Mn Spinel Oxides for Boosted Peroxymonosulfate Activation

AbstractTransition metal (TM)‐based bimetallic spinel oxides can efficiently activate peroxymonosulfate (PMS) presumably attributed to enhanced electron transfer between TMs, but the existing model cannot fully explain the efficient TM redox cycling. Here, we discover a critical role of TM−O covalency in governing the intrinsic catalytic activity of Co3−xMnxO4 spinel oxides. Experimental and theoretical analysis reveals that the Co sites significantly raises the Mn valence and enlarges Mn−O covalency in octahedral configuration, thereby lowering the charge transfer energy to favor MnOh–PMS interaction. With appropriate MnIV/MnIII ratio to balance PMS adsorption and MnIV reduction, the Co1.1Mn1.9O4 exhibits remarkable catalytic activities for PMS activation and pollutant degradation, outperforming all the reported TM spinel oxides. The improved understandings on the origins of spinel oxides activity for PMS activation may inspire the development of more active and robust metal oxide catalysts.

An Atomic-Scale Understanding of the Solution Chemistry of Antimony(V): Insights from First-Principles Molecular Dynamics Simulation.

In this study, the structure, hydrolysis, and complexation of Sb(V) in aqueous solution has been elucidated by using first-principles molecular dynamics (FPMD) simulations. The results show that both antimonic acid and its deprotonated form have an octahedral configuration, with average Sb-OH2 and Sb-OH distances of 2.25 and 2.05 Å, respectively. The computed pKa of [Sb(OH)5(OH2)] is 1.8, while [Sb(OH)6]- has an extremely high pKa. Consequently, [Sb(OH)6]- is the most dominant species of Sb(V) under common environmental conditions. A stable aqueous complex can form between [Sb(OH)6]- and common cations, and an Sb-Al bidentate complex has the largest dissociation free energy, followed by a Sb-Mg bidentate complex, indicating that they have significantly higher stabilities. For Na+ and Ca2+, their respective monodentate and bidentate complexes have similar dissociation free energies, indicating very close possibilities. These findings provide a comprehensive understanding of the solution chemistry of Sb(V) from a quantitative and microscopic perspective.

A new magnesium(II) complex of marbofloxacin: Crystal structure, antibacterial activity and acute toxicity

In this work, a new magnesium(II) complex was synthesized by solvothermal method using marbofloxacin (MB) as the medicinal ligand. The crystal structure of this complex ([Mg(MB)2(H2O)2], MB-Mg) determined by X-ray single crystal diffraction analysis demonstrates a mononuclear and six-coordinated octahedral configuration, in which two MB ligands chelate with Mg(II) through the 3-carboxyhydroxyl O atom and the 4-carbonyl O atom of MB, respectively, and two water molecules occupy the axial positions of the octahedron. The study on the solution chemistry by means of mass spectroscopy and molar conductivity further indicate that the coordinated species of MB-Mg could be still maintained in aqueous solution. The minimal inhibitory concentration (MIC) of MB and MB-Mg against seven typical species of pathogenic bacteria were tested in vitro. The results showed that MB-Mg exhibited better inhibitory effects on most the tested strains than MB. Furthermore, the acute toxicity was tested by acute toxicity test in mice. The results showed that the LD50 of MB-Mg was 9184.25 mg/Kg, which could be classified to Grade-II toxicity (practical non-toxic) according to the standard of toxicity classification standard. The acute toxicity in vivo, represented by LD50, is significantly lower than which of MB ligands (LD50 = 1249 mg/Kg, Grade-III toxicity). This result strongly suggests that the coordination of MB with the biosafe Mg(II) can effectively reduce its toxicity in vivo, contributing to the research of new metal-based veterinary drug products, with important practical value and scientific significance.

Complex Formation Between Zinc(II) and Alkyl-N-iminodiacetic Acids in Aqueous Solution and Solid State

Removal of metal compounds from wastewater using processes where metals can be removed and valuable chemicals recycled is of significant industrial importance. Chelating surfactants are an interesting group of chemicals to be used in such applications. Carboxylated polyamines are a promising group to be used in such processes. To apply carboxylated polyamines as chelating surfactants, detailed knowledge of the solution chemistry, including complex formation, kinetics and structures of pure fundamental systems, is required. In this study zinc(II) alkyl-N-iminodiacetate systems with varying length of the alkyl chain have been studied. Acidic and stability constants have been studied by potentiometry, and the structures of both solids and aqueous solutions have been determined by EXAFS. Zinc(II) forms two strong complexes with alkyl-N-iminodiacetates in aqueous solution. In an attempt to determine the acidic constants of these complexes, the deprotonation of the nitrogen atom in the complex bound ligands, it was observed that this reaction is very slow and no accurate values could be obtained. The bis(alkyl-N-iminodiacetato)zincate(II) complexes take, however, up two protons in the pH region 3–7, which means that this complex is approximately singly protonated in the pH region 3–7 and doubly protonated at pH < 3. The bis(n-hexyl-N-iminodiacetato)zincate(II) complex at pH = 13 has a distorted octahedral configuration with four short strong Zn–O bonds at 2.08(1) Å, while the Zn–N bonds are weaker at much longer distance, 2.28(2) Å. Similar configurations are also found in most reported structures of zinc(II) complexes with carboxylated amines/polyamines. The singly protonated complex seems to be five-coordinate, with four Zn–O bond distances at ca. 2.03 Å, and a single Zn–N bond distance in the range 2.15–2.25 Å. The relationship between the structure of the protonated bis(n-hexyl-N-iminodiacetato)zincate(II) complex and the slow kinetics in the region pH = 3–7 are discussed.

Crystal structure and electrical conduction mechanism of the new bi-tetrabutylphosphonium hexachlorostannate compound

The bi-tetrabutylphosphonium hexachlorostannate [P(C4H9)4]2SnCl6 compound is a new member of the family of organic-inorganic hybrid like perovskite system. This compound crystallizes in the monoclinic space group C2/c with unit cell parameters a = 14.4008 Å, b = 18.7256 Å, c = 17.5135 Å and β=113.1780° The (SnCl6)2− anions are surrounded by six [(C4H9)P]+ cations, forming an octahedral configuration. Regarding the differential scanning calorimetry, three order- disorder reversible phase transitions were observed at T1 = 388/363 K, T2 = 403/395 K and T3 = 446/410 K. Analysis of frequency and temperature dependence of impedance and electrical modulus spectroscopic data and Nyquist plots has shown the contributions of grains and grain boundaries to the electrical properties of the prepared material. The variation of the dielectric loss log (ε ‘’) with log (ω) is found to follow the empirical law, ε’’= Bωm(T). Moreover, the temperature dependence study of frequency exponent m (T) is investigated toexplain the conduction mechanism in the different parts, which is attributed to the non overlapping small polaron tunneling (NSPT) in the region I, II and III and by the correlated barrier hopping (CBH) model in phase IV.

Facile synthesis and deliberate characterization for new hydrazide complexes; cyclic voltammetry, crystal packing, eukaryotic DNA degradation and in-silico studies

New metal ion complexes were synthesized from new NO donor hydrazide ligand derived from acid hydrazide. All new synthesizes were investigated by all available analytical, spectral and theoretical tools. The ligand behaved as mononegative or neutral bidentate mode beside the effective presence of acetate group. UV–Vis microstate-transitions agree with octahedral configuration for most complexes except Cu(II) complex (square planer) which confirmed by Hamiltonian factors (g & f). While, Zn(II) complex is logically closes to tetrahedral configurations. TEM, XRD and EDX were performed for chosen complexes, to know some features of solid surfaces. Cyclic voltammogram for free Cu(II) ion, displayed clear broad reduction peak and almost one sharp oxidation peak. The electrochemical behavior was affected clearly in presence of the ligand. The structural forms were optimized for most compounds at suitable basis sets. Crystal models represent perfect contact surface with investigated crystals except Cd(II) complex. In-silico assay was carried out by Swiss-link (drug-likeness) and MOE-docking module, to evaluate the expected biological features. Distinguish lipophilicity and permeability were expected for Co(II), Ni(II) and Cu(II) complexes. Furthermore, MOE-docking performed, suggests Co(II), Ni(II) and Cu(II) complexes to form strong interaction with protein-pockets through allosteric binding types. Finally, preferable antibacterial behavior as well as electrophoretic mobility for calf-thymus DNA, were recorded almost with the same three complexes, in agreement with in-silico results.

A Simple and Efficient Method for Quantitative Synthesis of Cu (II) Complexes in Presence of SiO2: Structure Elucidation, DFT, Eukaryotic DNA, Antimicrobial and Potentiometric Studies

An effective methodology for the quantitative preparation of copper (II) complexes from benzaldehyde-[N-(3-Hydroxy-2-Naphthoyl)] Hydrazone (H2L) in existence of SiO2 as a catalyst which reduced reaction time and produced high yield was discussed. The formed complexes were elucidated by applying spectral, analytical and conformational methods. The octahedral configuration was proposed for Cu (II) complexes based on magnetic moments, electronic spectral and electron spin resonance (ESR). The DFT theory used to predict the optimized atomic-skeletons for all produced complexes. Also, biological activity measurements were performed to study the important of produced compounds. The association constants of ligand at various temperatures in 50% (v/v) DMSO/H2O, 0.05 M were calculated by applying potentiometric titration. Also, the stability constants of copper (II) compounds were calculated in DMSO/H2O as a mixed solvent at various temperatures.

Practical and computational studies on novel Schiff base complexes derived from green synthesis approach: Conductometry as well as in-vitro screening supported by in-silico study

A new Schiff base ligand was prepared and characterized then used to synthesize new metal ion complexes using ball milling technique. These complexes were elucidated by analytical, spectral and conformational tools, to establish their formulae. Mononuclear complexes (1M:1L) were proposed through neutral or mononegative mode within bidentate or tridentate binding. Octahedral configuration was proposed for all complexes except Pd(II) complex has square-planer geometry. EDX, SEM and XRD were used to known the elemental percentage, topographic features as well as the magnitude of crystallinity. Kinetic and thermodynamic parameters were estimated by two known methods. Conductometric titrations were carried out for Cu(II) and Ni(II) ions in presence or absence of the ligand to obtain association and formation constants. Crystal explorer software was used to build 3-D models for crystal packing systems according to Hirshfeld method. Strong molecular contact was observed for ligand models with high contribution for oxygen atom. Biological screening was elaborately handled towards microorganism, free radicals and colorectal carcinoma cell line (HCT-116). Excellent inhibition activity was clearly appeared with the ligand which sometimes exceeded reference drugs. Applying MOE, dynamic simulation was executed for the ligand towards different pathogen-proteins at top scoring poses. The interaction affinity towards protein-pockets as well as the electrostatic contour maps represent all interaction possibilities and confirm in-vitro results.

A first-principles study on electronic structure and crystal field effect of layered La2CuO4 as composed of CuO2 and La2O2 monolayers

Since the exact mechanism of superconductivity has not been completely understood yet, investigating this phenomenon is of great interest. Here, we first studied CuO 2 and La 2 O 2 monolayers separately and then investigated the changes in the electronic structure of the layered La 2 CuO 4 as formed by stacking those monolayers together. The results showed that when the two layers are sandwiched in tandem, a charge transfer mechanism occurs initially from La 2 O 2 to CuO 2 . This charge transfer mechanism results in localized orbitals that contribute to the bonds in CuO 2 , making them stronger. On the other hand, Cu dz2 orbitals move toward the Fermi level, being more delocalized. This phenomenon occurs by changing the crystal field effect on Cu atoms and creating the octahedral coordination of O atoms around Cu atoms. Therefore, due to the crystal field effect, the energy level of dz2 orbitals, which lie under those of dxz + dyz and dxy orbitals, ascend and lie under the energy level of dx2y2 orbitals. These changes in the electronic structure create a half-filled band around the Fermi level consisted of Cu dx2y2 and dz2 orbitals and apical O Pz orbitals. This configuration occurs by emptying the states due to La 2 O 2 near the Fermi level and occupying the states due to CuO 2 , lowering the bands in energy. The lowering separates the band around the Fermi level from other bands. • Changes in electronic structure are investigated during layers cited in the compound. • Change the characteristic of hoped electrons from electron like to hole like. • The formation of octahedral configuration changes the crystal field effect. • The vertical displacement of apical oxygen is influenced by the crystal field effect.

In Methanolic Solvent Synthesis of New MnII, CoII, NiII and CuII Schiff Base of Aromatic β Amino Acids: Spectroscopic, Thermal, Molecular Docking and Antimicrobial Studies

In this article, four new Schiff base complexes of Mn(II), Co(II), Ni(II) and Cu(II) complexes have been synthesized with two different compositions as [M(L)2Cl2] · nH2O and [M(L)2(H2O)2]Cl2 · nH2O [where L1 = benzoin-o-amino benzoic acid (aromatic β amino acid) and L2 = benzoin bromo-o-amino benzoic acid (aromatic β amino acid); M = MnII, CoII, NiII and CuII; n = 1, 2 and 4]. These Schiff base complexes were discussed by many tool of analyses like elemental analysis, magnetic susceptibility, molar conductance, mass spectra, infrared spectra "IR," proton nuclear magnetic resonance "1H-NMR," electronic spectral and thermogravimetric analysis (TG/DTG). These complexes have an electrolytic nature within range of 78–174 Ω1 cm–1 mol –1 based on conductance measurements. Magnetic moment and electronic spectral results deduced that the geometry of Mn2+, Co2+ and Ni2+ and Cu2+ complexes has an octahedral configuration. The number of coordinated and uncoordinated water molecules for the synthesized complexes were calculated based on the thermal analysis technique. The kinetic thermodynamic data were estimated by using commonly integral equations of Horowitz-Metzger (HM) and Coats-Redfern (CR). In vitro the antimicrobial activity of both free L1 and L2 ligands in comparable with their metal complexes were evaluated. This study was strengthen by molecular docking against three protein receptors, which attributing to selected organisms already used in vitro study.

Synthesis of Ethyl 2,2-Bis{[(benzoylcarbamothioyl)oxy]methyl}propanoate and Its Complexes with Copper(II) and Cobalt(II) Ions

The structures of ethyl 2,2-bis{[(benzoylcarbamothioyl)oxy]methyl}propanoate and its 1 : 1 complexes with copper(II) and cobalt(II) ions were determined by electronic absorption, IR, and 1H and 13C NMR spectroscopy and elemental analysis. The coordination entity in the complexes includes oxygen and sulfur atoms of the benzoyl and carbamothioyloxy groups of both ligand branches. The copper(II) ion has octahedral configuration with trigonal distortion, and the cobalt(II) ion has five-coordinate square–pyramidal configuration. The thermal behavior of the title compounds was studied by differential scanning calorimetry and thermogravimetric analysis.

Molybdenum speciation tracking hydrocarbon migration in fine-grained sedimentary rocks

Molybdenum (Mo) systematics (i.e., total concentration and isotope ratios) are widely used for the reconstruction of paleo-redox conditions in sedimentary records. However, the geochemical processes affecting the distribution of Mo in carbonaceous fine-grained sedimentary rocks remain unclear. This study investigates how the organic matter type may control Mo concentration and speciation in siltstone/shale strata of the Lower Triassic Montney Formation in the Western Canadian Sedimentary Basin (WCSB) to identify the effects of hydrocarbon expulsion and migration, fluid/rock interactions, and thermal maturity on Mo geochemistry when used as a paleo-redox proxy.The bulk Mo concentration in the studied samples varies from 0.2 to 86 ppm (mean = 13 ± 16.7 ppm), with Mo enrichment factors of 22.7 ± 24.4 suggesting an anoxic paleo-depositional setting. The X-ray Absorption Near Edge Spectroscopy (XANES) results show the presence of two separate Mo species within distinct geographic locations: (1) a group with a higher average Mo oxidation state where Mo is mostly surrounded by oxygen (O) atoms in an octahedral configuration, and (2) a group showing a lower average Mo oxidation state where Mo is mostly surrounded by sulfur (S) atoms in a tetrahedral configuration.The reduced Mo species are distributed in the vicinity of fault-related hydrothermal diagenesis/dolomitization zones. In contrast, the oxidized Mo species are found associated with samples enriched with solid bitumen/pyrobitumen. The results of our study show Mo speciation can significantly help to elucidate complex paleo-redox histories.

Hafnium Complexes $$[{\mathbf{P}}{{{\mathbf{h}}}_{{\mathbf{3}}}}{\mathbf{PR}}]_{{\mathbf{2}}}^{ + }$$[HfCl6]2–, where R = Et, CH2C6H4CN-4, or CH2C6H4F-4: Synthesis and Structure

The complexes $${\text{[P}}{{{\text{h}}}_{{\text{3}}}}{\text{PR]}}_{{\text{2}}}^{{\text{ + }}}$$ [HfCl6]2–, where R = Et (I), CH2C6H4CN-4 (II), or CH2C6H4F-4 (III), have been synthesized by the reaction between hafnium tetrachloride and tetraorganylphosphonium chlorides in acetonitrile and structurally characterized. According to X-ray diffraction data, the phosphorus atoms in tetraorganylphosphonium cations have a distorted tetrahedral coordination: the CPC angles are 108.07(8)°–110.89(8)° (I), 105.0(3)°–113.8(3)° (II), and 99.5(4)°–115.7(4)° (III), and the P–С bond lengths are 1.7958(17)–1.8042(19) A (I), 1.758(6)–1.834(6) A (II), and 1.714(8)–1.930(10) A (III). In the centrosymmetric octahedral anions [HfCl6]2– of complex I, the Hf–Cl distances are 2.4549(8)–2.4584(10) A. In complexes II and III, the octahedral configuration of anions is distorted: the trans-ClHfCl angles are 177.23(13)°–180.00° and 177.73(9)°, 178.07(10)°, 178.84(9)°, respectively, and the Hf–Cl bonds are 2.3949(18)–2.4976(17) A (II) and 2.411(2)–2.527(5) A (III). The structural organization of crystals is formed by weak hydrogen bonds Cl⋅⋅⋅Н–С (2.75–2.92, 2.63–2.94, and 2.75–2.83 A) between anions and cations.

Electro‐synthesis approach for some metal ion complexes derived from thiosemicarbazide; characterization, conformational, inhibitory simulation and Hirshfeld surface properties

Series of Co (II), Cu (II), Zn (II) and Sn (II) complexes derived from thiosemicarbazide ligand (HTSC), was synthesized by environmentally favorable method (electrochemical). All isolated complexes, were deliberately characterized by available analytical and spectral tools. The proposed molar ratio was 1:2 (M:L) as the only isolated one, beside the significant contribution for solvent molecules. The octahedral configuration was proposed for all complexes. Conformational analysis was implemented using advanced program to determine the best structural forms for complexes. Moreover, essential parameters were calculated to export important features for studied complexes. Meanwhile, Hirshfeld crystal surface properties, were interested to illustrate strength of packing interaction forces. Furthermore, distinction of site types inside the molecule and their H‐donor or H‐acceptor ability. Antimicrobial study was conducted against different microorganisms, to assert on the importance of new complexes in therapeutic field. Furthermore and to strengthen the study, the inhibition simulation was performed with respect to all complexes against selected pathogen proteins. Essential interaction data, were exported for each docking process, to classify inhibition efficiency. Co (II) and Cu (II) complexes were the complexes that played well in therapeutic simulation treatments against Bacillus subtilis (1bn8) and Candida albicans kinase (4c0t) proteins.

Binuclear titanium complexes coordinated by rigid p‐phenylene linked bis‐β‐carbonylenamine: Synthesis, structure, ethylene polymerization and copolymerization with 1,5‐hexadiene

Binuclear complexes for olefin polymerization have attracted great attention due to their unique catalytic properties compared with their mononuclear counterparts. Here a series of p‐phenylene‐bridgedbis‐β‐carbonylenamine ligands and their binuclear Ti complexes Ti2L1–Ti2L3 were prepared and characterized by 1H NMR, 13C NMR, Fourier transform infrared spectroscopy, and elemental analysis. The binuclear complex Ti2L3 bearing an octylthio sidearm was further investigated by single‐crystalX‐ray diffraction, which revealed that the ligand was of β‐imino enol form, with one titanium atom ligated with six other atoms, forming a deformed octahedral configuration. Furthermore, the ligand in Ti2L3 adopted a cis configuration, which was different from the trans configuration of its m‐phenylene‐bridged derivatives. These binuclear complexes (Ti2L1–Ti2L3) could catalyze ethylene polymerization and copolymerization with 1,5‐hexadiene(1,5‐HD) efficiently under modified methylaluminoxane activation. Compared with the mononuclear complex TiL5, the binuclear catalysts were thermally more stable and showed higher activity for ethylene polymerization at higher temperatures. The activity of these titanium complexes for the copolymerization of ethylene with 1,5‐HD were over 106 g/mol Ti.h.atm, almost twice as high as for homopolymerization. Compared with the mononuclear analogue TiL5 and the m‐substituted binuclear derivative Ti2L4, binuclear catalyst Ti2L2 showed higher activity and insertion rate of the comonomer. The activity of Ti2L2 was two to three times higher than that of TiL5 and Ti2L4, indicating that p‐substituted binuclear catalysts generate clear bimetallic synergistic effect for the copolymerization of ethylene and 1,5‐HD. Meanwhile, 1,5‐HD takes 1,3‐cyclopentyl form in the polymer by 1,3‐insertion. The copolymer prepared by binuclear catalysts had higher molecular weight and wider molecular weight distribution than that prepared by the mononuclear catalyst.

Synthesis, Structures and Photophysical Properties of Cationic Cyclometalated Iridium(III) Complexes Bearing N‐Phenylcarbazole Group

Four cationic cyclometalated IrIII complexes [(MeOPCz)2Ir(bpy)]PF6 (3), [(MeOPCz)2Ir(dtb‐bpy)]PF6 (4), [(TFPCz)2Ir(bpy)]PF6 (5), and [(TFPCz)2Ir(dtb‐bpy)]PF6 (6) were successfully synthesized using two new cyclometalated ligands 9‐phenyl‐3‐(4‐methoxypyridin‐2‐yl)‐9H‐carbazole (MeOPCz) 1 and 9‐phenyl‐3‐(4‐trifluoromethylpyridin‐2‐yl)‐9H‐carbazole (TFPCz) 2 in combination with 2,2'‐bipyridine (bpy) and 4,4'‐di‐tert‐butyl‐2,2'‐bipyridine (dtb‐bpy) as ancillary ligands. These complexes adopt the distorted octahedral configuration, and the complexes 5 and 6 crystallize in the centrosymmetric space group C2/c. Emission wavelength of these complexes can be tuned from 583 nm to 628 nm by the substituents (methoxy, trifluoromethyl and tert‐butyl groups) in ligands. All of these complexes show relatively high emission efficiencies (0.28–0.41) and short lifetimes (0.242–0.461 μs).