Transition Metal Ion Complexes Research Articles

Synthesis, Characterization and Evaluation of the Antimicrobial and Herbicidal Activities of Some Transition Metal Ions Complexes with the Tranexamic Acid.

New tranexamic acid (TXA) complexes of ferric(III), cobalt(II), nickel(II), copper(II) and zirconium(IV) were synthesized and characterized by elemental analysis (CHN), conductimetric (Λ), magnetic susceptibility investigations (μeff), Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), ultraviolet visible (UV-vis.), optical band gap energy (Eg) and thermal studies (TG/DTG and DTA). TXA complexes were established in 1 : 2 (metal: ligand) stoichiometric ratio according to CHN data. Based on FT-IR and 1H-NMR data the disappeared of the carboxylic proton supported the deprotonating of TXA and linked to metal ions via the carboxylate group's oxygen atom as a bidentate ligand. UV-visible spectra and magnetic moment demonstrated that all chelates have geometric octahedral structures. Eg values indicated that our complexes are more electro conductive. DTA revealed presence of water molecules in inner and outer spheres of the complexes. DTA results showed that endothermic and exothermic peaks were identified in the degradation mechanisms. The ligand and metal complexes were investigated for their antimicrobial and herbicidal efficacy. The Co(II) and Ni(II) complexes showed antimicrobial activity against some tested species. The obtained results showed a promising herbicidal effect of TXA ligand and its metal complexes particularly copper and zirconium against the three tested plants.

Pyrazolate-Bridged NHC Cyclometalated [Pt2] Complexes and [Pt2Ag(PPh3)]+ Clusters in Electroluminescent Devices.

The ionic transition metal complexes (iTMCs) [{Pt(C∧C*)(μ-Rpz)}2Ag(PPh3)]X (HC∧C* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazole-2-ylidene, X = ClO4/PF6; Rpz = pz 1a/2a, 4-Mepz 1b/2b, and 3,5-dppz 1c/2c) were prepared from the neutral [{Pt(C∧C*)(μ-Rpz)}2] (Rpz = pz A, 4-Mepz B, and 3,5-dppz C) and fully characterized. The "Ag(PPh3)" fragment is in between the two square-planar platinum units in an "open book" disposition and bonded through two Pt-Ag donor-acceptor bonds, as shown by X-ray diffraction (dPt-Ag ∼ 2.78 Å, 1a-1c). 195Pt{1H} and 31P{1H} NMR confirmed that these solid-state structures remain in solution. Photoluminescence studies and theoretical calculations on 1a, were performed. The diphenylpyrazolate derivatives show the highest photoluminescence quantum yield (PLQY) in the solid state. Therefore, 2c and its neutral precursor C were selected as active materials on light-emitting devices. OLEDs fabricated with C showed a turn-on voltage of 3.2 V, a luminance peak of 21,357 cd m-2 at 13 V, and a peak current efficiency of 28.8 cd A-1 (9.5% EQE). They showed a lifetime t50 of 15.7 h. OLEDs using 2c showed a maximum luminance of 114 cd m-2, while LECs exhibited a maximum luminance of 20 cd m-2 and a current efficiency of around 0.2 cd A-1, with a t50 value of 50 min.

Synthesis and Characterization of 4-(1-(2H benzo[d][1,2,3]triazol-2-ylimino)ethyl)benzonitrile and amino acid alanine and its Metal Complexes

The biological actions of transition metal ion complexes with mixed ligands are very different. Amino acid and azomethine containing Schiff bases are very useful building blocks for ternary complexes. The interaction of two ligands 4-(1-(2H-benzo[d][1,2,3]triazol-2-ylimino)ethyl)benzonitrile as L1 and an amino acid alanine as L2, with newly synthesized cuprous chloride solution in a 1:1:1 molar ratio using standard reflux approach has been attempted to create unique metal(I) complexes. Elemental analysis, molecular weight, magnetic moment, thermal analysis and spectroscopic methods are used to characterize the produced ligand and metal(I) complexes. Bacillus subtilis, Escherichia coli and Candida albicans were used as test organisms in antibacterial tests of the produced compounds. Antibacterial and antifungal activity of the metal (I) complexes have been shown to be very high against ciprofloxacin, ketoconazole.

Spectroscopic and biological studies of mixed ligand complexes of transition metal (II) ions with chloroquine and ketoprofen

To create fresh transition metal complexes of chloroquine and ketoprofen, we combined Ni(II), Co(II), Cu(II), and Zn(II). Metal analysis, IR, UV-vis, and X-ray diffraction (XRD) spectrum analyzes of the complexes were utilized to characterize them. The octahedral geometry was proposed for all compounds on the basis of the UV-vis and magnetic susceptibility data. The practical size of the ligands and complexes with crystallinity structure was in the nano range according to the XRD data. The antibacterial and antifungal activities of the ligands and their metal complexes have been examined.

A Smart Strategy for Prediction of Jahn-teller Distortion in Octahedral Complexes

This article describes the prediction of Jahn-Teller distortion in a smarter way just like a dial number method for electronic configurations d1 to d10 in the case of both high-spin (HS) and low-spin (LS) octahedral complexes of transition metal ions. These short tricks will help undergraduate chemistry students to solve problems associated with the prediction of Jahn-Teller distortion in the competitive examination, as it reduces the time in the exam hall. In addition, a few examples are explained based on smarter tricks for the prediction of Jahn-Teller distortion in octahedral complexes of transition metal ions.

Delving into theoretical and computational considerations for accurate calculation of chemical shifts in paramagnetic transition metal systems using quantum chemical methods.

The chemical shielding tensor for a paramagnetic system has been derived from the macroscopically observed magnetization using the perturbation theory. An approach to calculate the paramagnetic chemical shifts in transition metal systems based on the spin-only magnetic susceptibility directly evaluated from the ab initio Hilbert space of the electronic Zeeman Hamiltonian has been discussed. Computationally, several advantages are associated with this approach: (a) it includes the state-specific paramagnetic Curie (first-order) and Van Vleck (second-order) contributions of the paramagnetic ion to the paramagnetic chemical shifts; (b) thus it avoids the system-specific modeling and evaluating effectively in terms of the electron paramagnetic resonance (EPR) spin Hamiltonian parameters of the magnetic moment of the paramagnetic ion formulated previously; (c) it can be utilized both in the point-dipole (PD) approximation (in the long-range) and with the quantum chemical (QC) method based the hyperfine tensors (in the short-range). Additionally, we have examined the predictive performance of various density functional theory (DFT) functionals of different families and commonly used core-augmented basis sets for nuclear magnetic resonance (NMR) chemical shifts. A selection of transition metal ion complexes with and without first-order orbital contributions, namely the [M(AcPyOx)3(BPh)]+ complexes of M = Mn2+, Ni2+ and Co2+ ions and CoTp2 complex and their reported NMR chemical shifts are studied from QC methods for illustration.

Design Rule Hidden from The Eye in S/N‐Bridged Ancillary Ligands for Copper(I) Complexes Applied to Light‐Emitting Electrochemical Cells

AbstractEnhancing low‐energy emitting Cu(I)‐ionic transition metal complexes (iTMCs) light‐emitting electrochemical cells (LECs) is of utmost importance towards Cu(I)‐iTMC‐based white‐emitting LECs. Here, the ancillary ligand design includes (i) extension of π‐systems and (ii) insertion of S‐bridge between heteroaromatics rings. This led to two novel heteroleptic Cu(I)‐iTMCs: 2‐(pyridin‐2‐yl‐l2‐azanyl)quinoline (CuN2) and 2‐(naphthalen‐2‐ylthio)quinoline (CuS2) as N^N and bis[(2‐diphenylphosphino)phenyl] ether as P^P, exhibiting improved photoluminescence quantum yields (ϕ) and thermally activated delayed fluorescence processes compared to their reference Cu(I)‐iTMCs: di(pyridin‐2‐yl)‐l2‐azane (CuN1) and di(pyridin‐2‐yl)sulfane (CuS1). Despite CuS2 stands out with the highest ϕ (38% vs 17 / 14 / 1% for CuN1 / CuN2 / CuS1), only CuN2‐LECs show the expected enhanced performance (0.35 cd A−1 at luminance of 117 cd m−2) compared to CuN1‐LECs (0.02 cd A−1 at6 cd m−2), while CuS2‐LECs feature low performances (0.04 cd A−1 at 10 cd m−2). This suggests that conventional chemical design rules are not effective towards enhancing device performance. Herein, nonconventional multivariate statistical analysis and electrochemical impedance spectroscopy studies allow to rationalize the mismatch between chemical design and device performance bringing to light a hidden design rule: polarizability of the ancillary ligand is key for an efficient Cu(I)‐iTMC‐LECs. All‐in‐all, this study provides fresh insights for the design of Cu‐iTMCs fueling research on sustainable ion‐based lighting sources.

Inert Transition Metal Ion Complexes in Organic Synthesis: Protection and Activation.

Single crystal X-ray diffraction studies for a variety of metal ion complexes of functionalised sarcophagines (sarcophagine = sar = 3,6,10,13,16,19-hexa-azabicyclo[6.6.6]icosane) have further confirmed not only that the form of the metal ion/sar unit is unique for each metal, albeit with a sensitivity of the conformation to the associated counter anions, but also that for any given metal and ligand substituent, the dimensions (bond lengths and angles) of the complex and the substituent at the secondary nitrogen centres do not differ significantly from those of the isolated components. Despite this, where the substituent contains reactive sites, the reactivity differs markedly from that of their form in an uncoordinated substrate.Rationalisations are offered for these differences, in part through the use of Hirshfeld surface analysis of the intermolecular interactions. The kinetic inertness of the complexes means that the metal ions can be considered to act as regioselective protecting groups.

Regulating energy gap in Ir-based ionic complexes to generate near-infrared emissions: Application in solid-state light-emitting electrochemical cells

Solid-state light-emitting electrochemical cells (LECs) exhibit high potential for commercial electronics owing to their simple solution-processable device architectures, low-voltage operation, and compatibility with inert metal electrodes. However, the low device efficiency of most deep-red and near-infrared (NIR) LECs hinders their application (external quantum efficiency (EQE) < 1.00%). In this study, we demonstrate a simple method to tune the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of iridium-based ionic transition metal complexes (iTMCs) to generate NIR emissions. We investigate a series of cationic iridium complexes with small energy gaps, with 2,2′-bibenzo[d]thiazole fixed as N^N ligand moiety mainly controlling the LUMO energy level, changing a series of C^N ligands. All complexes exhibited deep red/NIR phosphorescence, and these combined devices provided emission peaks at 690–730 nm and were applied as components in LECs, exhibiting a maximum EQE of 1.78% in electroluminescence devices. Using a host–guest emission system with the iridium complex YIr as the host and complex TBBI as the guest, the highest EQE of LECs could be further enhanced to>2.34%, which is the highest value reported for NIR LECs.

Cu(II) and Zn(II) crystal complexes based on pyrazolone: Synthesis and application as antibacterial agents

4-Benzoyl-3-methyl-1-phenyl-5-pyrazolone (HPMBP) was synthesized via the Friedel–Crafts reaction and characterized through 1H NMR spectroscopy, Infrared spectroscopy and Electrospray ionization time-of-flight(ESI-TOF). The Cu(II) and Zn(II) coordination complexes, namely, [Cu(HPMBP)(2,2′-bpy)(Cl)]·H2O(1) and [Zn(HPMBP)(2,2′-bpy)(Cl)]·H2O(2), were synthesized in CH3OH(HPMBP:2,2′-bipyridine:M = 1:1:1, M = Cu, Zn). Single crystal X-ray diffraction(SCXRD) studies show that Cu(II) and Zn(II) exhibit a distorted square pyramidal configuration through two oxygen atoms of HPMBP, two cis-nitrogen atoms of 2,2′-bipyridine and monodentate chloride ion. Moreover, the Hirshfeld surface analysis of the in complexes was performed using crystallographic calculations. Furthermore, the antibacterial activities of 1 and 2 are more potent than HPMBP, in particular, the antimicrobial properties of 2 are better than those of 1. Scanning electron microscopy (SEM) indicated that 1 had a regular strip shape, while 2 had an irregular circular shape. Our work provides a theoretical basis for studying the antibacterial activity of transition metal ion complexes.

The Effect of the Interface Layer on the Electronic Parameters of the Light Emitting Electrochemical Cell (LEC) Device Based on Iridium (III) Complex that Calculated by Different Methods

We report a calculation of the electronic parameters and some optical measurement results of a light-emitting electrochemical cell (LEC), one of the most basic forms of electroluminescent films by modifying 4-(4-methoxy-N-naphthalen-1-ylanilino) benzoic acid (MA) as hole injection layer doped with an emissive layer that is ionic transition metal complex (Ir[dF(CF3)ppy]2(dtbpy))PF6-(Ir-iTMC). The electronic parameters of LEC device were computed using three different methods; Cheung and Cheung’s, Conventional Schottky and Norde, to evaluate the ideality factor (n), the barrier height () and the series resistance (Rs) of the LEC device. The formation on indium tin oxide (ITO) substrate was analyzed by Atomic Force Microscopy (AFM). The HOMO-LUMO energy level and electronic charge distribution of the MA molecule were computed theoretically using Chemissian software. The MA’s HOMO-LUMO energy level is determined to be EHOMO = −5.27 eV and ELUMO = −1.40 eV. The ITO surface has been modified with the Self-Assembled Monolayers (SAM) technique as an interlayer to improve the surface working function by simplifying hole injection from the ITO anode to the Hole Transport Layer (HTL) in the LEC. The Ir- iTMC complexes containing Π-conjugated bridging ligand shown better external quantum efficiency (EQE), reaching to 1.49%. The max luminance values of the bare-LEC and LEC-MA are measured as 145 cd m−2 and 1240 cd m−2, respectively.

Review on Isatin- A Remarkable Scaffold for Designing Potential Therapeutic Complexes and Its Macrocyclic Complexes with Transition Metals.

Role of synthetic coordination chemistry in pharmaceutical science is expeditiously increased due to its sundry relevances in this field. The present review endows the synthesized macrocyclic complexes of transition metal ions containing isatin and its derivatives as ligand precursors, their characterization and their copious pharmaceutical applications. Isatin (1H-Indole-2,3-dione) is a protean compound (presence of lactam and keto moiety permits to change its molecular framework) that can be obtained from marine animals, plants, and is also found in mammalian tissues and in human fluids as a metabolite of amino acids. It can be used for the synthesis of miscellaneous organic and inorganic complexes and for designing of drugs since it has remarkable utility in pharmaceutical industry due to its wide range of biological and pharmacological activities, for instance anti-microbial, anti-HIV, anti-tubercular, anti-cancer, anti-viral, anti-oxidant, anti-inflammatory, anti-angiogenic, analgesic activity, anti-Parkinson’s disease, anti-convulsant etc. This review provides extensive information about the latest methods for the synthesis of isatin or its substituted derivatives based macrocyclic complexes of transition metals and their plentiful applications in medicinal chemistry.

(Gd3+) Complexation with oligopeptide (SFVG) and amyloid peptide (Aβ13–23) in aqueous solution by NMR spectroscopy

Gadolinium (III) ion, which belongs to the subgroup of transition metal ions, has practical importance for magnetic resonance imaging (MRI) with contrast. The accumulation of complexes of transition metal ions with amyloid peptides in the human body leads to the formation of insoluble plaques, which are presumably-one of the causes of Alzheimer's disease. This paper presents the results of studying the interaction of the gadolinium (III) ion with a fragment of amyloid protein Aβ40 in aqueous solutions using nuclear magnetic resonance spectroscopy. Tetrapeptide (SFVG) was used as the simplified model of metal-peptide interaction research. Beta-amyloid peptide (Aβ13-23) was chosen as the amyloid protein Aβ40 fragment model. Analysis of 1H NMR spectra revealed that the interaction exists for both types of molecules. It was also suggested the possible location of gadolinium (III) ion in the studied molecules.

Long-Wavelength Light-Emitting Electrochemical Cells: Materials and Device Engineering.

Long-wavelength light-emitting electrochemical cells (LECs) are potential deep-red and near infrared light sources with solution-processable simple device architecture, low-voltage operation, and compatibility with inert metal electrodes. Many scientific efforts have been made to material design and device engineering of the long-wavelength LECs over the past two decades. The materials designed the for long-wavelength LECs cover ionic transition metal complexes, small molecules, conjugated polymers, and perovskites. On the other hand, device engineering techniques, including spectral modification by adjusting microcavity effect, light outcoupling enhancement, energy down-conversion from color conversion layers, and adjusting intermolecular interactions, are also helpful in improving the device performance of long-wavelength LECs. In this review, recent advances in the long-wavelength LECs are reviewed from the viewpoints of materials and device engineering. Finally, discussions on conclusion and outlook indicate possible directions for future developments of the long-wavelength LECs. This review would like to pave the way for the researchers to design materials and device engineering techniques for the long-wavelength LECs in the applications of displays, bio-imaging, telecommunication, and night-vision displays.

Transparent Light‐Emitting Electrochemical Cells

AbstractSingle layer light‐emitting electrochemical cells (LECs) are amongst the simplest electroluminescent devices and operate with air‐stable electrodes. Transparent light‐emitting devices are of great interest as they can enable new applications in consumer electronics. In this work, a transparent ionic transition metal complex based LEC is fabricated by developing a transparent top contact based on tin (IV) oxide (SnO2) and indium‐tin oxide, processed by low‐temperature atomic layer deposition and pulsed laser deposition, respectively. The resulting devices present transparency in excess of 75% over the full visible spectrum (380–750 nm), with 82% transmission at the emission peak (563 nm). The devices emit from the front and the rear with high luminance (260 cd m−2) and long lifetime (176 h). These parameters place them among the highest performing single layer transparent electroluminescent devices.

Phosphonium-Based Ionic Thermally Activated Delayed Fluorescence Emitters for High-Performance Partially Solution-Processed Organic Light-Emitting Diodes

Phosphonium-Based Ionic Thermally Activated Delayed Fluorescence Emitters for High-Performance Partially Solution-Processed Organic Light-Emitting Diodes

Preparation and Characterization of New (Halogenated Azo-Schiff) Ligands with Some of their Transition Metal Ions Complexes

Two new halogenated azo-Schiff ligands were prepared in two steps. The first step included a condensation between 4-amino acetophenone and 2-fluoro-4-bromo aniline to give the corresponding Schiff base. In the second step, the diazonium salt of this Schiff base reacted with 2-naphthol and 4,5-diphenylimidazole to form two new azo-Schiff base derivatives as ligands; (3-((E)-(4-((E)-1-((4-bromo-2-fluorophenyl) imino)ethyl) phenyl) diazenyl) naphthalen-2-ol (HSBAN) (L1) and ((E)-N-(4-bromo-2-fluorophenyl)-1-(4-((E)-(4,5-diphenyl-1H-imidazol-2-yl)diazenyl) phenyl) ethan-1-imine) (HSBAI) (L2), respectively. These new ligands were characterized by mass spectrometry, FT-IR, 1H NMR, UV-Visible spectroscopy and elemental microanalysis (CHN). Five divalent transition metal ion complexes (Co, Ni, Cu, Cd, and Hg) were prepared and characterized, beyond the determination of the optimal condition (concentration, pH value, and the mole ratio M:L) using UV-visible studies. Additionally, complementary techniques, such as atomic absorption, electrical conductivity and magnetic susceptibility, were performed to deduce their geometries. The comprehensive study suggested an octahedral geometry for all complexes except Cd and Hg complexes of the first ligand.

Complexation, Bio-evaluation, Magnetic Susceptibility and Thermodynamic study of Newly Synthesized Pharmacologically active Schiff base with La(III), Ce(III) and Sm(III)

Present research work describes the successful development of inner transition metal ion complexation, magnetic susceptibility study, thermodynamic parameters and biological applications of synthesized organic ligand. Stability constant Order of developed metal complexes of N-[-(4-chlorophenyl) methylene] isonicotinohydrazide was found as follows La(III) &gt; Ce(III) &gt; Sm(III). Positive μeff clearly indicates paramagnetic nature of developed complexes. During thermodynamic parameter examination we found stability constants for complexes decrease with an increasing temperature, indicating that the composition equilibrium is exothermic in nature. Also ΔH and ΔG were negative for all of the systems which suggested that all of the reactions were exothermic. The ΔS found positive for most of the complexes which indicate in metal-ligand binding process is entropy favourable. In antimicrobial evaluation, we observed that Sm+3 metal complexes of (N-[(E)-(4-chlorophenyl) methylene] isonicotinohydrazde) exhibit superior property specifically against gram negative bacteria with respect to organic ligand.

Thermodynamic Study of the formation of transition metal ion complexes carrying medicinal drug in mixed solvent media

Thermodynamic Study of the formation of transition metal ion complexes carrying medicinal drug in mixed solvent media

Blue light-emitting electrochemical cells incorporating aggregation-induced emission small molecules

The light-emitting electrochemical cells (LECs) have received extensive attention from researchers in recent years due to their simple single-layer structure, air-stable metal electrodes, and low manufacturing cost. So far, reports on the use of LEC active layer emitter materials have mainly focused on ionic transition metal complexes (iTMCs) and conjugated polymers (CPs). The application of the above materials in blue LECs is restricted due to high cost, complicated synthesis process, and poor stability, which results in the slow development of blue LECs. A novel blue LECs device based on aggregation-induced emission (AIE) small molecule (2,3-diphenylbenzo[b]thiophene S, S-sulfur dioxide, DP-BTO) with a peak luminance of 36.58 cd/m2, a CEmax of 1.14 cd/A, and an EQEmax of 0.46% was reported in this work. The blue light emission centered at ~460 nm was exhibited at a voltage above 6 V. This work successfully constructed blue light-emitting LECs devices based on AIE materials, opening up a new research avenue for the application of AIE materials in the field of thin-film device development.