Copper Compounds

The ability of oxindolimine copper(II) and zinc(II) complexes, known to have antitumor activity, to inhibit human topoisomerase IB has been tested through enzymatic kinetic assays and molecular docking simulations. These copper and zinc compounds are able to inhibit remarkably the cleavage reaction and only partially the religation step, the copper compound being more efficient than the zinc one. A complete inhibition activity of the cleavage is only obtained when the enzyme is pre-incubated with the compound, the inhibition being irreversible and reversible for the copper and zinc compounds, respectively. The relative stability of such complexes was estimated by competitive equilibria with human serum albumin (HSA), monitored by CD spectroscopy. The copper species shows a log KCuL = 17.2, while the analogous zinc complex exhibits a log KZnL = 7.2. Molecular docking simulation studies show that the almost square planar geometry of the copper compound allows a direct coordination of the metal with two amino acids (Glu492, Asp563) of the enzyme at variance of the zinc compound which has a more tetrahedral geometry. Altogether, the data indicate that the different coordination geometry achieved by the two transition metal ions has an important role in modulating their efficiency as topoisomerase I inhibitors.

Herein we investigated the luminescence mechanism of one "carbene-metal-amide" copper compound with thermally activated delayed fluorescence (TADF) using density functional theory (DFT)/multireference configuration interaction, DFT, and time-dependent DFT methods with the polarizable continuum model. The experimentally observed low-energy absorption and emission peaks are assigned to the S1 state, which exhibits clear interligand and partial ligand-to-metal charge-transfer character. Moreover, it was found that a three-state (S0, S1, and T1) model is sufficient to describe the TADF mechanism, and the T2 state should play a negligible role. The calculated S1-T1 energy gap of 0.10 eV and proper spin-orbit couplings facilitate the reverse intersystem crossing (rISC) from T1 to S1. At 298 K, the rISC rate of T1 → S1 (∼106 s-1) is more than 3 orders of magnitude larger than the T1 phosphorescence rate (∼103 s-1), thereby enabling TADF. However, it disappears at 77 K because of a very slow rISC rate (∼101 s-1). The calculated TADF rate, lifetime, and quantum yield agree very well with the experimental data. Methodologically, the present work shows that only considering excited-state information at the Franck-Condon point is insufficient for certain emitting systems and including excited-state structure relaxation is important.

Bacterial blight, caused by Xanthomonas citri pv. punicae (Xcp), severely impacts the global pomegranate industry, with alarming yield losses up to 80%. This pathogen becomes a glitch in the pomegranate industry, leading to reduced commercial pockets globally, especially in Pakistan. The objective of this study was to conduct biochemical characterisation and in vitro evaluation of copper compounds and antibiotics against Xcp, for optimal fruit quality and yield. The pathogen was isolated from infected tissues of the pomegranate, and various biochemical tests were performed to identify the bacteria. Pathogenicity was confirmed using the pin-prick and infiltration method on cv. Golden. The in vitro efficacy of antibiotics and copper compounds was assessed using the disk diffusion method against Xcp. The pathogen was aseptically cultured via the streak plate method, and disks impregnated with different chemical concentrations were placed on solidified media. A control disk was treated with sterile water containing 1% v/v surfactant. Plates were incubated at 28 ± 2°C for 48 and 72h to observe bacterial growth inhibition. Biochemical analysis showed positive results for the oxidase test, catalase test, KOH solubility test, gelatin liquefaction, and starch hydrolysis test, while Gram staining was negative. Antibacterial efficacy was determined by measuring inhibition zones after 48 and 72h of incubation. The highest inhibition zones, measuring 29.55mm and 37.73mm at 48 and 72h, respectively, were recorded with 550µg/ml oxytetracycline hydrochloride, followed by streptomycin sulfate (550µg/ml) with zones of 29.12mm and 32.42mm. In contrast, copper-based compounds, particularly copper sulfate (2000µg/ml), exhibited the lowest inhibition, with zones of 8.85mm and 8.86mm at the respective time intervals. A comparative analysis demonstrated that antibiotics showed outstanding and prodigious results compared to copper compounds. The results of this experiment demonstrate the effectiveness of oxytetracycline hydrochloride and streptomycin sulfate in inhibiting the radial growth of Xcp under controlled conditions. Furthermore, changes in dosage/concentration, time of application, and field application method may help researchers with field-oriented results in the future.

Necrogenic Gram-negative bacterium Erwinia amylovora, which causes economic losses especially in pome fruits such as apple, pear, quince and loquat, some berries and many ornamental plants, causes fire blight disease. Copper compounds are used extensively in disease control programs and they can cause toxicproblems in terms of plant and environmental health. In addition, the formation of resistance to copper in the pathogen is frequently observed. In this study, plant activator phosphorous acid and biological control agent Bacillus subtilis, and 3 different copper compounds, Copper sulfate, Copper oxychloride and Copper hydroxide which are commonly used against E. amylovora, on apple cv. Gala with M9 rootstock were evaluated comparatively. When the new season shoot lengths of 3-year-old plants with homogeneous growth reached 20-25 cm, chemicals and B. subtilis were applied first time before one week ago from the pathogen inoculation, and after 2 times with 1 week intervals. The youngest two leaves at tips of actively growing terminal plant shoots were inoculated by cutting off using scissors dipped in suspension of E. amylovora str. EaARADY5 containing 108 CFU ml-1. Disease assessments were made after the disease severity (%) was determined on the basis of shoot blight after symptom development of the disease stopped, and the results were found to be statistically significant (p<0.05). According to the findings, while the highest effect was obtained by copper oxychloride with 69% effectiveness among all applications, the lowest effectiveness was obtained with 43.5% copper sulfate. It has been revealed that the use of the most effective of the copper compounds in field applications will result in less exposure to chemicals in terms of human and environmental health, and that B. subtilis and phosphorous acid can be used significantly in the integrated control of fire blight.

On the specific heat of some layered copper compounds: I. Lattice contribution

Evaluation of Sustained Antibacterial Effect of Alcohol-Based Disinfectant Containing Monovalent Copper Compound Against Antibiotic-Resistant Bacteria

Bacterial pustule of soybean (Glycines max) caused by Xanthomonas axonopodis pv. glycines is one of the most prevalent bacterial diseases of soybean. This bacterium shows strong pathogenicity to the plants and distributes throughout Korea. However, no good control measures including bactericides and resistant cultivars are available to control the disease in Korea. Therefore, this study was conducted to develop chemical control method against soybean bacterial pustule. The present study was undertaken to find out the growth inhibitory effect bactericides (8 antibiotics, 2 copper compounds, quinoline, 18 agro-chemicals) on bacterial pustule pathogen. Antibiotics test showed that tetracycline and streptomycin sulfate significantly suppressed the growth of bacterial pustule pathogen. Also, application of oxolinic acid was found to be effective for pathogen inhibition. However, vancomycin, polymyxin B sulfate and copper compounds did not show the positive suppressive effect on growth of the pathogen. Among the eighteen agro-chemicals, streptomycin sulfate + oxytetracyclin (18.8 + 1.5%) WP, oxytetracycline (17%) WP and oxolinic acid (20%) WP were found to be effective for the inhibition of the pathogen in vitro. The selected 5 agro-chemicals were also applied on soybean in field and their control effects against the soybean bacterial pustule were tested. The foliar application of streptomycin sulfate + oytetracyclin WP and oxytetracycline WP on the naturally infected soybean (Taekwangkong) showed high control value (above 70%). Therefore, it is concluded that the bactericides used in this study showed strong inhibitory effect to soybean bacterial pustule and they can be recommend to farmers to control the disease.

Reactions of some (polyhaloaryl)copper compounds with acid chlorides and chlorosilanes

In recent decades, pollution levels have increased, mainly as a result of the intensive anthropogenic activities such industrial development, intensive agricultural practices, among others. The impact of metals and organic contaminants is, nowadays, a great concern to the scientific and political communities. Copper compounds are the main sold pesticides in Europe, as well as herbicides, including glyphosate. Diphenyl ethers are the second ones most sold. Glyphosate and copper compounds are intensively studied, but the opposite is seen in the case of diphenyl ethers, including fluorinated pesticides (e.g., oxyfluorfen). Some research has been performed to increase the knowledge about these contaminants, daily inputted on the aquatic systems and with dangerous effects at physical and biochemical levels on the organisms. A wide range of biomarkers (e.g., growth, survival, reproductive success, enzymatic activity, lipid metabolism) has been applied to determine the potential effects in many species. This review intends to: (a) perform a compilation of the knowledge in previous research about the action mode of organic (fluorinated-based herbicide) and inorganic (copper-based pesticides) contaminants; (b) carry out an information survey about the lethal and sub-lethal effects of the fluorinated-based pesticides, namely the oxyfluorfen and the copper-based pesticides, on aquatic species from different trophic levels, according to in vitro and in vivo studies; (c) understand the impact of oxyfluorfen and copper-based pesticides, considering their effects reported in in vitro studies and, simultaneously, the authorized concentrations by legal organizations and the effective concentrations of each pollutant found in the environment. The literature analyzed revealed noxious effects of Cu and oxyfluorfen to aquatic organisms, including freshwater and marine species, even when exposed to the reference as well as to environmental concentrations, thus highlighting the importance of more monitoring and ecotoxicological studies, to chemical pollutants and different species from different ecological niches, to sustain and improve the legislation.

It is shown that bismuth compounds whose action is very similar to the action of lead-containing catalysts are quite effective catalysts of combustion of propellants of various compositions. The influence of bismuth compounds on the burning rate of propellants considerably increases when they are introduced together with carbon black and copper compounds. For a certain range of compositions, various copper compounds in combination with carbon black or without it are rather effective catalysts of combustion.

Chromatographic determination of copper speciation in jet fuel

Wastewater purification from heavy metal compounds is a complex and urgent task. One of the main sources of pollution of the environment with ions of heavy metals is the wastewater, i.e., washing, of the electro-plating processes. Complex electrolytes based on copper compounds are stable in a wide pH range and, when released into water, cannot be removed by the traditional methods, such as neutralization and precipitation. The study estimated the efficiency of various methods of physicochemical water purification for removing complex ammonia-tartrate copper (II) complexes from water. Findings of research show that titanyl sulfate is most effective in water purification using coagulants. The efficiency of purification with the use of titanium compounds reaches 85 %, which is on average 30--40 % higher than when using traditional coagulants based on aluminum or iron compounds. Electrocoagulation processes make it possible to effectively remove complex copper compounds from water due to a combination of the processes of organic component oxidation and coagulation with iron salts. It was found that advanced oxidation processes, which are based on the reaction with a hydroxyl radical, using hydrogen peroxide, i.e., Fenton processes, make it possible to purify wastewater from copper compounds by 99.9 %. Despite the high efficiency, it is advisable to use adsorption processes only at the stage of additional water purification from previously coagulated and oxidized pollutants

The effect of the type of organometallic iron or copper compounds on the value of the absorbance signals of these metals in an air-acetylene flame and for iron in a dinitrogen oxide-acetylene flame is reported. The determination of iron and copper in xylene solutions of the asphaltene and resinous petroleum fractions was carried out using various organometallic compounds of both metals as standards and by both the calibration graph and standard additions techniques. There are serious limitations to the direct flame atomic-absorption spectrometric methods, owing to transport interferences. In addition, with iron, there are matrix interferences caused by the structure of the petroleum samples being analysed and also owing to the various forms of iron present in these samples. It is recommended that determination of these elements in heavy petroleum fractions should be carried out by dry mineralisation and flame atomic-absorption spectrometric analysis of aqueous solutions.

Cu 1s→3d XANES of divalent- and trivalent- copper compounds

Luminescence properties of copper(I), zinc(II) and cadmium(II) coordination compounds with picoline ligands