Cobalt Metal Complexes Research Articles

Metal Complexes of Cobalt Chloride with Vinyl‐, Allyl‐ and Styrylbenzimidazole Ligands: Synthesis, Structure, and Properties

AbstractThree N‐substituted benzimidazole cobalt(II) complexes have been synthesized and fully characterized by elemental analysis, FT‐IR spectroscopy, and X‐ray crystallography. The crystal packing formation features were studied by AIM analysis, and the energy and nature of both weak noncovalent interactions in the crystal and metal–ligand coordination bonds were assessed. These N‐coordinated cobalt(II) complexes were screened for antimicrobial activities against Gram‐negative (Escherichia coli, Bacillus subtilis) and Gram‐positive (Enterococcus durans) bacteria. Minimal inhibitory concentrations (MIC = 6.2 mg/mL) were found for complex cobalt chloride with allylbenzimidazole ligands against E. durans and E. coli. Its antimicrobial activity is several times higher compared to the reference gentamicin. Molecular docking made it possible to consider the nature of binding of cobalt metal complexes with vinyl‐, allyl‐ and styrylbenzimidazole ligands to biological targets and estimate their energy. The binding energy meanings depend on protein and ligand type, and reaches 8 kcal/mol.

Bioactive benzhydrazone derived Schiff base and its metal(II) complexes: Synthesis, characterisation, cytotoxicity, DNA binding/cleavage, antimicrobial and antioxidant activity

Bivalent mononuclear transition metal complexes of cobalt, nickel, copper and zinc were synthesized from (E)-2-(1-(2-(2-hydroxybenzoyl)hydrazono)ethoxy)benzoic acid. The FTIR, 1H NMR, 13C NMR, HR-Mass, UV–Vis., EPR, Powder XRD and SEM analysis were employed to investigate the structural features of synthesized compounds. The spectral data confirmed the square planar geometry of the complexes. The EPR spectra of the Cu(II) complex supported the proposed geometry. Powder X-ray diffraction (PXRD) analysis and scanning electron microscopy (SEM) imaging revealed that the complexes consist of nano-sized grains exhibiting a polycrystalline structure. The in vitro antimicrobial efficacy of the compounds was evaluated against various bacterial and fungal strains using the well diffusion method. The in vitro antibacterial activity demonstrated that all synthesized compounds were biologically active, and Zn(II) complex exhibited the highest inhibitory activity against S. aureus (gram-positive bacteria). For antioxidant activity, the free ligand and its metal chelates were evaluated using the standard DPPH method, revealing that the Co(II) complex displayed least inhibitory concentration value (IC50 = 16 ± 2.3 μg/mL) indicating the highest antioxidant activity. DNA interaction studies showed intercalation between complexes and DNA, and the Cu(II) complex exhibited a higher binding affinity of 2.78 ± 0.34 × 105 M−1. The DNA cleavage ability of the compounds was assessed using gel electrophoresis, demonstrating the effective cleavage of the pBR322 plasmid DNA. The Schiff base and its complexes were subjected to an anticancer evaluation against the human breast cancer cell line (MCF-7) using the MTT assay method. The percentage cell inhibition of the compounds was calculated.

Catalytic Activity of 2-Imino-1,10-phenthrolyl Fe/Co Complexes via Linear Machine Learning.

In anticipation of the correlations between catalyst structures and their properties, the catalytic activities of 2-imino-1,10-phenanthrolyl iron and cobalt metal complexes are quantitatively investigated via linear machine learning (ML) algorithms. Comparatively, the Ridge Regression (RR) model has captured more robust predictive performance compared with other linear algorithms, with a correlation coefficient value of R2= 0.952 and a cross-validation value of Q2= 0.871. It shows that different algorithms select distinct types of descriptors, depending on the importance of descriptors. Through the interpretation of the RR model, the catalytic activity is potentially related to the steric effect of substituents and negative charged groups. This study refines descriptor selection for accurate modeling, providing insights into the variation principle of catalytic activity.

Nanostructured Metal Oxides Synthesized via Simple Thermal Decomposition of Co(II), Ni(II), Cu(II), and Zn(II) Schiff Base Complexes: Characterization and Antimicrobial Activity

Some new transition metal complexes of Cobalt (II), Nickel (II), Copper (II), and Zinc (II) with Schiff base ligand resulting from the condensation of 3,5-dichlorosalicylaldehyde and 2-aminophenol were synthesized in an ethanolic medium. Both ligand/complexes were characterized by some physicochemical techniques such as FTIR, UV, NMR, Mass, TGA, and SEM. The CHN elemental analysis data showed the formation of 1:1 [M:L] complexes. Magnetic susceptibility balance helps to find the magnetic values of the metal complexes. The various nanoparticles were prepared from metal complexes. The invitro antimicrobial activity was screened against the pathogens.

Synthesis, Spectral Characterization, Electrochemical, Antioxidant and Antimicrobial Evaluation of 3d-Metal Complexes of 3-Mercapto-4-(Pyren-1-ylmethylene)Amino-1,2,4-Triazin-5-One

New transition metal complexes of cobalt(II), nickel(II), copper(II) and zinc(II) with new Schiff base [HLp] derived from pyrene-1-carbaldehyde and 4-Amino-3-mercapto-5-oxo-1,2,4-triazine were synthesized and characterized by elemental analysis, 1H-NMR, FT-IR, UV-Visible, ESR spectral studies, magnetic moment measurements and cyclic voltammetry. Results prove that [HLp] acts as bidentate ligand. Low conductance data reveal non-electrolytic nature of the complexes. The spectroscopic data and magnetic moment values along with elemental analytical data support octahedral geometries for Co(II), Ni(II), Zn(II) complexes and square planar geometry for Cu(II) complexes. ESR spectra of Cu(II) complexes exhibited g values trend as g ∥ > g ⊥ > g e . The nephelauxetic ratio (β) along with orbital reduction factors (K values) report the covalent nature of the metal-ligand bonds in complexes. Thermal analysis was also carried out to propose the composition of complexes and to determine their thermal stability. Coats-Redfern method was employed to evaluate some kinetic parameters of thermal degradation processes. In vitro antimicrobial properties of all synthesized compounds were investigated. After assessing the inhibition zones, metal complexes have been found more antimicrobial active than the Schiff base against both bacterial as well as fungal strains. Metal complexes also showed remarkable fluorescence and antioxidant properties.

Role of metal complexes in inhibition of cancer growth factors

Cancer is characterized by uncontrolled cell growth, representing a hallmark feature marked by sustained proliferation. This heightened proliferative capacity is primarily driven by the influence of growth factors. Scientific evidence suggests that growth factors play a crucial role in augmenting the transcription of specific proto-oncogenes, such as myc and fos. In the context of cancer development, these growth factors can be either produced by the cancer cells themselves or induce normal cells to release them through intricate signaling mechanisms. The functional diversity of growth factors encompasses various actions, but their predominant mode of operation is through the tyrosine kinase receptor pathway. Tyrosine kinase receptors, comprising integral membrane complexes with intrinsic kinase activity in their cytoplasmic domain, play a pivotal role in transducing signals initiated by the binding of specific growth factors (ligands). This binding event triggers the activation of the kinase function within the receptor, resulting in the phosphorylation of downstream targets on tyrosine and serine residues. Subsequently, this phosphorylation event recruits additional molecules into signaling cascades, amplifying the cellular response. Transition metals, such as Copper, Zinc, and Cobalt, integral to biological systems, play pivotal roles in normal physiological functions. However, dysregulation of these essential metals has been implicated in the pathogenesis of various disorders, including cancer. The narrative unfolds by elucidating the critical role of growth factors in cancer cell proliferation. Key growth factors, such as Transforming Growth Factor-β, Tumour Necrosis Factor-α and Insulin-like Growth Factors, are explored within the context of cancer progression. The intricate signaling pathways, particularly the Tyrosine Kinase Receptor pathway, are examined to understand how metal complexes may disrupt these pathways, impeding uncontrolled cell growth. Furthermore, this review provides an in-depth examination of medicinal inorganic chemistry, emphasizing the ability of transition metal complexes to form charged ions and induce hydrolysis reactions. The nuanced discussion underscores the necessity for precise dosages of metal-containing drugs to avoid undesirable toxicity, acknowledging the delicate balance required for optimal therapeutic responses. This comprehensive review delves into metal complexes of Cobalt, Copper, Zinc, and metal nanoparticles as promising inhibitors of cancer growth factors. By explicating the intricate interplay between metal complexes and growth factor pathways, this article contributes to the ongoing scientific exploration of novel and effective anticancer strategies.

Effect of Copper and Cobalt Metal Complex Redox Mediator Based Xanthan Gum Gel Electrolyte Materials on Performance of Dye Sensitized Solar Cells

AbstractIn this study, we report the first application of (4‐(tert‐butyl) benzyl or 4‐methyl benzyl)‐substituted 2‐(pyridin‐2‐yl)‐1H‐benzo[d]‐imidazole coordinated copper and cobalt redox shuttles Cu [((tbb) pbi)2]+1/+2, Cu [(mbpbi)2]+1/+2, Co [((tbb) pbi)3]+2/+3 and Co [(mbpbi)3]+2/+3 based xanthan gum gel electrolytes (XGE‐1, XGE‐2, XGE‐3 and XGE‐4) in fabrication of Dye sensitized solar cells. Interestingly, XGE‐1 and XGE‐2 obtained higher efficiency of 4.08 and 3.04 % under 1sun illumination. Specifically, highly donor moiety 4‐(tert‐butyl)benzyl)‐substituted (on N−H position) 2‐(pyridin‐2‐yl)‐1H‐benzo[d]‐imidazole ligands coordinated, Cu [((tbb) pbi)2]+1/+2 gel electrolyte achieved best performance due to its appropriate redox potential of 0.80 V versus Normal Hydrogen Electrode. This high performance also confirmed with the interfacial studies of the devices. As per the computational results, the copper redox mediators conquered lower reorganization energy and free energy about (0.11‐0.20 & 0.18–0.27 eV) due to the effect of ligands structure. Overall, Cu [((tbb) pbi)2]+1/+2 act as redox shuttle for highly proficient DSSCs.

Formulation and Comparison of Glucomannan Metallocomplexes Made of Cobalt and Copper

The broad category of pharmaceutical science in which drugs are complex with metals like platinum, zinc iron, etc is defined as Metallopharmaceutics. The earliest work on Metallopharmaceutics is around 700 BC. In this work, Glucomannan, which is a plant-based drug, is used as a ligand to prepare anti-diabetic metal complexes of Cobalt and copper. Glucomannan is basically a polymer thought up of -(14)-linked D-mannose and D-glucose in a straight chain in a ratio of 8:5. Various pre-formulation studies were performed including swelling index and angle of repose for the pure drug only. The pre-formulation parameters inferred that the pure drug has fair flow properties with a swelling index of 81.8%. Formulations were analyzed spectrophotometrically using ATR-IR and UV-spectroscopy. In UV spectroscopy, it was analyzed that Glucomannan showed a distinct peak at 267 nm. Formulation of metal complexes was performed using the solvent-assisted method. The dissolution studies and release kinetics were performed for prepared Formulations (F1-F9). The Formulation F9 proved to be the best formulation following the Higuchi Diffusion plot with maximum linearity of 0.997. Thus, 500 mg Glucomannan + 1000 mg Cobalt (F9) had the sustained drug release throughout the dissolution period.

A Highly Active Nitrogen‐Doped Mixed‐Phase Mixed‐Valence Cobalt Nanocatalyst for Olefins and Nitroarenes Hydrogenation

AbstractDevelopment of an inexpensive, environmentally friendly and robust recyclable heterogeneous catalyst for alkene and nitroarene hydrogenation is in high demand for the sustainable future of chemical industries. Herein, we have synthesize and characterized a trinuclear mixed valence cobalt complex 1 and nitrogen doped mixed phase cobalt (β‐Co(OH)2 and CoO) nanocatalyst (N@MPCoNC) as reported earlier. N@MPCoNC was synthesized via single source molecular precursor by reducing 1 by aq. N2H4 followed by calcinations. Both mixed‐valence cobalt metal complex (1) and nitrogen doped mixed phase cobalt nanocatalyst (N@MPCoNC) were utilized for alkenes and nitroarenes hydrogenation reaction, however excellent catalytic activity was noticed by N@MPCoNC with the 100 % conversion of styrene and 4‐nitrotoluene to the corresponding ethylbenzene and 4‐aminotoluene with 100 % selectivity under mild reaction condition. The scope of the heterogeneous N@MPCoNC was further evaluated for other alkenes and nitroarenes to obtain corresponding alkanes and aminoarenes with an excellent conversion and high selectivity at room temperature.

In-silico docking, synthesis, structure analysis, DFT calculations and energy frameworks of metal complexes to regress angiogenesis activity

Angiogenesis is the formation of new blood vessels and capillaries from pre-existing blood vessels. In general, it plays an important role in the development of tumors, as tumors never grow beyond 2 to 3 mm without angiogenesis processes which supply the essential nutrient to the tumor. Therefore, blocking the angiogenesis process is one of the promising strategies to inhibit cancer cell growth. Metals are essential for several biochemical reactions in living organisms. It is a cellular component selected by nature to function in many biological processes. Metal complexes show a broad range of pharmacological activity and considerable efforts are made for the development of metal complexes as drugs. Encouraged by this information, the metal complexes of Cobalt(II), Nickel(II), Zinc(II), Cadmium(II), and Copper(II) derivative of N, N’ Bis-(3,4,5-trimethoxy benzylidene)–benzene–1,2-diamine have been synthesized from o-phenylene diamine in the alcoholic medium. The metal complexes (M1−M5) were characterized using different techniques like 1H NMR, Fourier-transform infrared spectral data, mass spectral data, thermo gravimetric studies, magnetic susceptibility data, molar conductance, ESR, and micro-elemental analysis. The result obtained from the characterization results reveals that all the metal complexes (M1−M5) obtained were square planar except one which was octahedral configuration. The DNA binding, cleavage and anti-angiogenesis activity shown by the complexes (M1−M5) were significantly better than the ligand. Also, complexes M2 and M3 showed the highest anti-angiogenic activity and decreasing intensity of lane as compared with other synthetic complexes. In-silico docking simulations predicted the anti-angiogenesis activity of the complexes against homo sapiens of VEGFR-2 and exhibited prominent interactions at the active site pocket region. Moreover, density functional theory (DFT) was applied to calculate HOMO-LUMO, energy gap, and other parameters under PBE1PBE functional with lanl2dz basis sets.

Innovative Construction of the Cobalt Metal Complex Redox Electrolyte and Octahedron Structure of the Cobalt Metal Organic Framework Electrode in the Energy Storage and Energy Conversion System

One of the most important tasks in improving supercapacitor (SC) efficiency is the quest for advanced electrode and electrolyte materials. For the first time, we propose using a metal organic frame...

Antimicrobial Activities of Schiff Base Metal Complexes of First Transition Series

The correlative antimicrobial analysis of amino acid Schiff base and derivatized tren metal complexes: A= [MLCl2], B= [ML(CH3OH)2], respectively, against fungal strains, Candida parapsilosis, Candida albicans, Candida krusei, and Cryptococcus neoformans and (Gram-negative) P. aeruginosa, E. coli, S. typhimurium, and S. pyogenes, Methicillin-resistant Staphylococcus aureus (MRSA), S. mutans (Gram-positive) bacterial strains had been done by disk diffusion method following McFarland protocol. [CuLCl2] and [Cu (CH3OH)2] manifest overwhelming activity against microbes than other metal complexes of cobalt, nickel and zinc. Minimum inhibition concentration data also shows that copper complexes have the lowest MIC values against these tested microorganisms. The significance of this investigation is to uncover shielding and constructive therapeutic agents that wield against bacterial and fungal infection.

Synthesis, Characterization and Antibacterial Activity Study of Cobalt(II), Nickel(II), Copper(II), Palladium(II), Cadmium(II) and Platinum(IV) Complexes with 4-Amino-5-(3,4,5-trimethoxyphenyl)-4<i>H</i>-1,2,4-triazole-3-thione

New transition metal complexes of cobalt(II), nickel(II), copper(II), palladium(II), cadmium(II), and platinum(IV) with bidentate ligand 4-amino-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazole-3-thiol were synthesized and characterized by microelemental analyses (CHNS), Fourier-transform infrared (FT-IR), UV-Visible spectra, molar conductance, magnetic susceptibility and thermal analyses (TG-DSC). The ligand was synthesized by ring closure of potassium-2-(3,4,5-trimethoxybenzoyl) hydrazine carbodithioate with an excess amount of hydrazine, and then was acidified using hydrochloric acid. The ligand was used as Lewis bases to prepare metal complexes through the reaction of ratio (1:2) metal:ligand. The ligand was characterized by 1H-NMR and 13C-NMR and the previously described methods to identify the complexes. The results obtained from spectra and elemental analyses indicated the tetrahedral geometry around Cd(II) ion, square-planar for Cu(II) and Pd(II), and octahedral geometry around Co(II), Ni(II), and Pt(IV). All the metal complexes showed significant antibacterial activity in comparison with the free ligand. The antibacterial test of the platinum(IV) complex showed higher activity than other metal complexes against bacteria Staphylococcus aureus (G-positive) and Escherichia coli (G-negative).

Effect of 1-Substituted 2-(Pyridin-2-yl)-1H-Benzo[d]imidazole Ligand-Coordinated Copper and Cobalt Complex Redox Electrolytes on Performance of Ru(II) Dye-Based Dye-Sensitized Solar Cells

A comparative study has been attempted on 1-substituted 2-(pyridin-2-yl)-1H-benzo[d]imidazole ligand-coordinated copper and cobalt metal complex electrolytes Cu+/2+[nbpbi]2(PF6-)1/2, Cu+/2+[npbi]2(PF6-)1/2, Co2+/3+[nbpbi]3(PF6-)2/3, and Co2+/3+[npbi]3(PF6-)2/3 in dry acetonitrile coupled with both N3 and N719 dyes in dye-sensitized solar cell (DSSC) devices. Impressively, the copper metal sites coordinated with ligands nbpbi (L1) and npbi (L2) shift the redox potential about 190-200 mV and pave the way to achieve remarkably higher power current efficiency, which is clarified with cyclic voltammetry, electrochemical impedance spectrum, electron lifetime, and quasi Fermi-level experimental results. Overall efficiencies of 4.99, 4.82, 3.26, and 3.19% under 1 sun conditions (100 mW cm-2) were obtained for Cu+/2+[nbpbi]2(PF6-)1/2 and Cu+/2+[npbi]2(PF6-)1/2 electrolytes coupled with the sensitizers (N3 and N719 dyes), which are considerably higher than those acquired for devices containing the cobalt electrolytes. These results signify a record for copper complex-based electrolytes coupled with ruthenium dyes in liquid DSSCs. In particular, bulky acceptor 4-nitro benzyl moiety-substituted 2-(pyridin-2-yl)-benzimidazole (on the N-H position) (ligand L1)-coordinated copper metal complex electrolytes achieved higher efficiency, approaching a suitable redox potential of 0.68 V versus NHE. At the same time, the napthyl moiety-substituted 2-(pyridin-2-yl)-benzimidazole (ligand L2)-coordinated copper metal complex electrolytes showed less redox potential due to its donating nature. It was determined that the Jsc and PCE increment of the devices consisting of Cu+/2+[nbpbi]2(PF6-)1/2 electrolytes was mainly attributed to various factors such as higher chemical capacitance, larger charge, longer electron life time, a downward shift in the quasi Fermi level of TiO2, the slow recombination process, and fast dye regeneration. These results make easily tunable metal complexes bearing a new sort of 1-substituted 2-(pyridin-2-yl)-1H-benzo[d]imidazole ligand-based electrolytes as very promising copper electrolytes for further improvements of extremely efficient liquid DSSCs.

Peculiarities of electronic structure and chemical bonding in iron and cobalt metal complexes of porphyrazine and tetra(1,2,5-thiadiazole)porphyrazine

The geometrical and electronic structures of iron and cobalt metal complexes of porphyrazine and tetra(1,2,5-thiadiazole)porphyrazine in ground and low-lying excited electronic states were determined by DFT calculations and the complete active space (CASSCF) method with following accounting dynamic correlation by multiconfigurational quasidegenerate second-order perturbation theory (MCQDPT2). A geometrical structure of D[Formula: see text] symmetry has been obtained for all four complexes. According to data obtained by the MCQDPT2 method, the complexes of cobalt and iron possess the ground states 2A[Formula: see text] and 3A[Formula: see text], respectively, and wave functions of the ground states have the form of a single determinant. It is shown that the crystal field theory (CFT) can be used to describe the sequence of electronic states of the investigated complexes. The nature of the bonds between metal atoms and nitrogen atoms has been described using the analysis of the electron density distribution in the frame of Bader’s quantum theory of atoms in molecule (QTAIM).

Synthesis, Characterization, Biological and Photoluminescence Study of Co(II) Complexes of Fused Heterocyclic Ring Systems

Abstract: Aim: To synthesize and characterize the transition metal complexes of fused heteroccylic ring systems. Background: Many of the fused ring heterocyclic compounds were found to be biologically active in the literature like anti-microbial, anti-cancer, anti-inflammatory, anti-oxidant and so on. The present work focus on the synthesis of the biologically active compounds. Materials and Methods: Synthesis of the ligands and the complexes are done using the standard procedures in earlier reports. Melting points were found using open glass capillaries on a Raaga melting point apparatus and are uncorrected. The percentage of C, H, N , infra-red and UV-Visible spectra of the compounds were recorded using Elementar Vario EL III CHN analyser, Shimadzu spectrophotometer (4000-400 cm-1) and Elico SL 159 UV-Vis spectrophotometer respectively. The antimicrobial activity of the compounds was carried out by well diffusion method. The anticancer activity of the compounds were carried out for the MCF-7 cell line (breast Cancer) using MTT assay. Discussion and Conclusion: Structural elucidation of newly synthesized Co(II) metal complexes of fused heterocyclic ring systems were done using various spectral techniques like FT-IR, 1H-NMR, Electronic and TGA-DTA studies. The anti-microbial activity of the prepared complexes and the DNA Cleavage studies were screened for various test pathogens and explained. The photoluminescence property of the fused heterocyclic ligand and their complexes were studied and compared. Fluorescence enhancement is observed in these complexes which is contradictory to the normal Fluorescence quenching phenomena by added organic derivatives, paved way for photochemical applications. Key words: Tetrazoloquinoxaline, Fused heterocycles, Anti-microbial, Flouresence, DNA Cleavage, Cobalt metal complexes.

Designing Single-Molecule Magnets as Drugs with Dual Anti-Inflammatory and Anti-Diabetic Effects.

We have designed and synthesized two novel cobalt coordination compounds using bumetanide (bum) and indomethacin (ind) therapeutic agents. The anti-inflammatory effects of cobalt metal complexes with ind and bum were assayed in lipopolysaccharide stimulated RAW 264.7 macrophages by inhibition of nitric oxide production. Firstly, we determined the cytotoxicity and the anti-inflammatory potential of the cobalt compounds and ind and bum ligands in RAW 264.7 cells. Indomethacin-based metal complex was able to inhibit the NO production up to 35% in a concentration-dependent manner without showing cytotoxicity, showing around 6–37 times more effective than indomethacin. Cell cycle analysis showed that the inhibition of NO production was accompanied by a reversion of the differentiation processes in LPS-stimulated RAW 264.7 cells, due to a decreased of cell percentage in G0/G1 phase, with the corresponding increase in the number of cells in S phase. These two materials have mononuclear structures and show slow relaxation of magnetization. Moreover, both compounds show anti-diabetic activity with low in vitro cell toxicities. The formation of metal complexes with bioactive ligands is a new and promising strategy to find new compounds with high and enhanced biochemical properties and promises to be a field of great interest.

Synthesis, Spectroscopic and Computational Studies of Some Metals Chelates with Chromene-2-one and Pyrazine-Based Ligands

The present paper deals with the synthesis of cobalt(II), nickel(II), copper(II) and cadmium(II) complexes with two bidentate ligands, L1 (3-(quinoxaline-2-yl)-coumarin) and L2 (2-methylene-2H-chromene-3-(methyl carbonimidic)thioanhydride). The L1 ligand was prepared by treating w-bromo-3-acetylcoumarin with 1,2-phenylenediamine whereas the ligand L2 was prepared through substitution reaction ofw-bromo-3-acetylcoumarin with potassium thiocyanate in ethanol medium. The confirmation of the structures for L1 and L2 were done by (C.H.N.S.) elemental analysis, FT-IR, NMR and mass spectra. The metal complexes of cobalt(II), nickel(II), copper(II) and cadmium(II), with L1 and L2, were prepared and isolated in the solid state then characterized by (C.H.N.M) elemental analysis, proton and carbon-13 NMR, FT-IR and mass spectra. Furthermore, the thermal analysis (TG-DSC) for some complexes assisted us in the elucidation of the suggested structures of complexes and confirmed their thermal stability. The results obtained from elemental analysis, magnetic susceptibility and thermal analysis confirmed that all metal complexes were formed in 2:1 molar ratio of ligand to metal with octahedral structures except cadmium(II) complexes which were in a tetrahedron geometry with 1:1 mole ratio. The complexes are found to be soluble in DMF and DMSO. The results obtained from TG-DSC analysis revealed that the metal complexes were thermally stable with point decomposition over 350 °C. The DFT/TDDFT calculations were carried out to provide the electronic structures and spectra of the compounds.

Cobalt complex dye as a novel sensitizer in dye sensitized solar cells

In this study, cobalt metal complex has been introduced as a novel class of sensitizer for more mechanistic consideration of the photovoltaic conversion efficiency (PCE) of dye sensitized solar cells. UV–vis spectroscopy of dye illustrates maximum absorption at wavelengths of dye in 498 and 650 nm. TiO2 was used as the photoanode of the cell whose x-ray diffraction spectrum indicates that its crystal phase is anatase (101). Surface morphology of photoanode was also investigated by scanning electron microscopy (SEM) and obviously showed ∼25 nm TiO2 nanoparticles. The cyclic voltammetry (CV) investigation of Pt-coated fluorine doped tin oxide (FTO) as the counter electrode of the cell indicates redox process on this electrode. Photovoltaic measurements of cobalt complex sensitized solar cell show that the short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF%) and photovoltaic conversion efficiency (PCE%) are 48.80 μA.cm−2, 0.7 V, 44% and 0.09% at the air mass 1.5 (100 mW.cm−2) irradiation condition, respectively. The high light harvesting efficiency (LHE) (∼61%) and high molar absorption coefficient of the cobalt complex dye (12,500 M−1.cm−1) were other optical advantages of the cobalt complex sensitized solar cell. The results indicate the quantum yield of electron injection (φing) which depends on dye structure as a parameter influences the JSC. The pyridine rings conformation in donor part of the cobalt complex dye plays a significant role in φing and subsequently PCE. These findings open a new insight about mechanistic aspects of dye sensitized solar cells efficiency.

Cobalt(II) Chloride Complex of Propylene-1,3-diamine as CO2 Absorber

A new CO2 absorber is reported in this paper. When CoCl3 is mixed with propylenediamine at room temperature and atmospheric ambient pressure, the extremely low concentration of CO2 in the air can be absorbed to form a stable metal complex [Co(PPD)2CO3]Cl·H2O (PPD = 1,3-propylenediamine). The CO2 capture capacity can reach 23.6 wt. %. Although Co is relatively expensive, the practical use of cobalt metal complexes produced still needs to be developed. This study provides an idea of capturing CO2 at low concentration under normal conditions. Through the structural characterization and performance study of complex [Co(PPD)2CO3]Cl·H2O, a new method for CO2 capture was explored. Thermogravimetric analysis data show that the compound [Co(PPD)2CO3]Cl·H2O has the ability to desorption CO2 and H2O at 160-220 ºC, and the ability to adsorb CO2 or regenerate CO2 is being explored. The electrochemical property of compound [Co(PPD)2CO3]Cl·H2O were also investigated.