Triazine Complex Research Articles

Comparative Study of Total Antioxidant Capacity (TAC) Levels of Pregnant Women on Intermittent Preventive Treatment with Sulphadoxine Pyrimethamine and their Controls in Malaria Endeminicity

Background: The issue of malaria prevention in endemic areas during antenatal periods needs continuous emphasis so as to achieve its desired goals. Its roles in reducing the problems of malaria in pregnancy has been proven. The problems of anaemia in pregnancy, preterm labours, small for gestational age babies have been greatly reduced by adequate practice of Intermittent Preventive Treatment with Sulphadoxine Pyrimethamine (IPT-SP). It is also advocated that optimal levels of antioxidants like Total Antioxidant status (TAC/TAS) is necessary to assist pregnant women enjoy uneventful pregnancies as well as avert other problems associated with pregnancy. Such problems may include preterm births, neonatal anaemias, intrauterine growth retardations (IUGR), increased admissions into special care baby units and even neonatal deaths. Objectives: We have comparatively studied the plasma Total Antioxidant Capacity / Status levels in parturients who received intermittent preventive treatment with sulphadoxine pyrimethamine (IPT-SP), and their controls during current confinements. Method: This study was carried out at the Federal Medical Centre (FMC), Owerri Nigeria. Owerri, the capital of Imo state Nigeria and has a typical malaria endemic setting as seen in most parts of Sub-Saharan Africa. Ethical clearance and subsequent certification were obtained from the ethics committee of FMC Owerri enabling the commencement of the longitudinal recruitment of participants. This was after an adequate counseling and informed consent involving both groups. As a laboratory based, cross-sectional descriptive study, it involved 296 participants who clearly satisfied the inclusion criteria for either the study or control groups as allotted longitudinal. Participants were followed up after recruitment through their entire antenatal course till delivery to enable collection of blood samples for the estimation of Total Antioxidant Status/Capacity which was done using the Ferric Reducing Ability of Plasma, FRAP; by (Benzie and Strain, 1996). The methodology principle is based on the fact that at low pH, antioxidant power causes the reduction of ferric tripyridyl triazine (Fe III TPTZ) complex to ferrous form (which has an intense blue colour) that can be monitored by measuring the change in absorption at 593nm. FRAP values are obtained by comparing the absorbance change at 593 nm in mixture (test), with those containing ferrous ion in known concentration (Standard). Data analysis: The data obtained was analysis using the computer Software Package for Social Science (SPSS) version 20.0 (SPSS, Inc, 2007, Chicago) while the descriptive statistics (mean, standard deviation, range, percentages etc) were determined for continuous variables. P-value less than (<0.05) at 95% confidence interval was considered statistically significant. Result: The mean serum level of total antioxidant status (TAS) in the study group was 846.55 umol/l while the minimum and maximum serum Total antioxidant status were 706 and 991 umol/l respectively. For their controls, the mean serum level of Total antioxidant status was 833.70 umol/l. However, the minimum and maximum serum Total antioxidant statuses were 291 and 1065 umol/l respectively. The difference was not statistically significant (p= 0.167) with odds ratio 1.00 (CI of 95% 0.997-1.006).

Cobalt-Catalyzed Hydrosilylation of Carbon Dioxide to the Formic Acid, Formaldehyde, and Methanol Level─How to Control the Catalytic Network?

The selective hydrosilylation of carbon dioxide (CO2) to either the formic acid, formaldehyde, or methanol level using a molecular cobalt(II) triazine complex can be controlled based on reaction parameters such as temperature, CO2 pressure, and concentration. Here, we rationalize the catalytic mechanism that enables the selective arrival at each product platform. Key reactive intermediates were prepared and spectroscopically characterized, while the catalytic mechanism and the energy profile were analyzed with density functional theory (DFT) methods and microkinetic modeling. It transpired that the stepwise reduction of CO2 involves three consecutive catalytic cycles, including the same cobalt(I) triazine hydride complex as the active species. The increasing kinetic barriers associated with each reduction step and the competing hydride transfer steps in the three cycles corroborate the strong influence of the catalyst environment on the product selectivity. The fundamental mechanistic insights provide a consistent description of the catalytic system and rationalize, in particular, the experimentally verified opportunity to steer the reaction toward the formaldehyde product as the chemically most challenging reduction level.

Controlling the Product Platform of Carbon Dioxide Reduction: Adaptive Catalytic Hydrosilylation of CO2 Using a Molecular Cobalt(II) Triazine Complex.

The catalytic reduction of carbon dioxide (CO2) is considered a major pillar of future sustainable energy systems and chemical industries based on renewable energy and raw materials. Typically, catalysts and catalytic systems are transforming CO2 preferentially or even exclusively to one of the possible reduction levels and are then optimized for this specific product. Here, we report a cobalt‐based catalytic system that enables the adaptive and highly selective transformation of carbon dioxide individually to either the formic acid, the formaldehyde, or the methanol level, demonstrating the possibility of molecular control over the desired product platform.

Controlling the Product Platform of Carbon Dioxide Reduction: Adaptive Catalytic Hydrosilylation of CO2 Using a Molecular Cobalt(II) Triazine Complex

AbstractThe catalytic reduction of carbon dioxide (CO2) is considered a major pillar of future sustainable energy systems and chemical industries based on renewable energy and raw materials. Typically, catalysts and catalytic systems are transforming CO2 preferentially or even exclusively to one of the possible reduction levels and are then optimized for this specific product. Here, we report a cobalt‐based catalytic system that enables the adaptive and highly selective transformation of carbon dioxide individually to either the formic acid, the formaldehyde, or the methanol level, demonstrating the possibility of molecular control over the desired product platform.

Novel ruthenium(II) triazine complex [Ru(bdpta)(tpy)]2+ co-targeting drug resistant GRP78 and subcellular organelles in cancer stem cells

Ruthenium(II/III) metal complexes have been widely recognized as the alternative chemotherapeutic agents to overcome the drug resistance and tumor recurrence associated with platinum derivatives. In this work, a novel ruthenium(II) triazine complex namely, 1 ([Ru(bdpta)(tpy)]2+) was synthesized and spectroscopically characterized. Drug resistant cancer stem cells (CSCs) were used to evaluate the cytotoxicity of Ru(II) complex 1. The complex 1 showed a greater cytotoxic potential with IC50 values lower than that of cisplatin. The intracellular localization assay confirmed that the complex 1 was effectively distributed into mitochondria as well as endoplasmic reticulum (ER), and executed a ROS-mediated calcium and Bax/Bak dependent intrinsic apoptosis. Interestingly, direct interaction between complex 1 and glucose regulated protein 78 (GRP78), a protein associated with drug resistance caused the ROS-mediated ubiquitination of GRP78. Notably, western blot and confocal microscopy analysis confirmed that complex 1 significantly reduced the protein levels of GRP78. Dose-dependent in vivo antitumor efficacy against CD133+HCT-116 CSCs derived tumor xenograft further validated that complex 1 could be an effective chemotherapeutic agent.

Characterization and evaluation of antioxidant activity of Cajanus cajan and Pisum sativum

The present study was designed to investigate the anti-oxidant activity of the ethanolic extract of Cajanus cajan and Pisum sativum. The ethanolic extract was evaluated by UV Spectrophotometer. Anti-oxidant activity of ethanolic extract was determined by FRAP method. The FRAP means the Ferric ion reducing Antioxidant Power. At low pH, reduction of ferric tri-pyridyl triazine (Fe3+ TPTZ) complex to ferrous form (which has intense blue colour) can be monitored by measuring the change in adsorption at 593 nm. The reduction is non-specific, is that any half reaction that has lower redox potential, under reaction conditions, than that of ferric ferrous half reaction will derive the ferrous (Fe3+ to Fe2+) in formation. The change in absorbance is therefore directly related to the combined or total reducing power of the electron donating antioxidant present in the reaction mixture.

Theoretical study of interactions between electron-deficient arenes and coinage metal anions

The binding behavior of coinage metal anions with some electron-deficient arenes has been investigated by MP2 calculations, and the character of interactions in these complexes has been examined by NBO analysis. The results indicate that coinage metal anions can interact with electron-deficient arenes to form anion-π, strong σ-type and hydrogen-bonding complexes. The σ-type structure is the global minimum for triazine, trifluorotriazine, hexafluorobenzene and tricyanobenzene, and the hydrogen-bonding structure is the global minimum for trifluorobenzene. There exist some differences in the stability of anion-π complexes for coinage metal anions: the anion-π complexes of Au(-) are minima expect for triazine complex; the anion-π complexes of Ag(-) are minima expect for tricyanobenzene complex; and the anion-π complexes of Cu(-) are not minima expect for trifluorobenzene complex. The binding strength of anion-π and hydrogen-bonding complexes for Au(-) is larger than that for Ag(-) and Cu(-), but the binding strength of σ complex displays a different sequence: Cu(-) > Au(-) > Ag(-). The binding behavior of coinage metal anions is more similar to that of F(-) than that of Cl(-) and Br(-). The relaxed potential energy surface scans for some selected systems have been performed to help understand the interactions between coinage metal anions with electron-deficient arenes.

Kinetics and mechanism of substitution of iron(II)–triazine complexes by 1,10-phenanthroline

The kinetics and mechanism of substitution of some iron(II)–triazine complexes, namely \( {\text{Fe}}({\text{PDT}})_{3}^{2 + } \), \( {\text{Fe}}({\text{PDTS}})_{3}^{4 - } \), \( {\text{Fe}}({\text{PPDT}})_{3}^{2 + } \) and \( {\text{Fe}}({\text{PPDTS}})_{3}^{7 - } \) (PDT = 3-((2-phenyl)-5,6-diphenyl))-1,2,4-triazine, PDTS = 3-(2-pyridyl)-5,6-bis(4-phenylsulfonicacid)-1,2,4-triazine disodium salt, PPDT = 3-((4-phenyl-2-pyridyl)-5,6-diphenyl)-1,2,4-triazine and PPDTS = 3-(4-(4-phenylsulfonicacid)-2-pyridyl)-5,6-bis(4-phenylsulfonicacid)-1,2,4-triazine trisodium salt) by 1,10-phenanthroline (phen) have been studied by conventional spectrophotometry in acetate buffers over the pH range 3.6–5.6, by following the absorbance of the triazine (tz) complexes at their respective absorption maxima. The reactions were carried out under pseudo-first-order conditions, that is, [phen] ≫ [Fe(II)–triazine]. The reactions were found to be first order in both Fe(II)triazine complex and phen. The rates increase with increasing pH. Plots of kobs versus [phen] are linear with positive intercepts, and also plots of kobs against 1/[H+] are linear with positive intercepts on the rate axes, indicating that the reactions proceed by both phen– and hydrogen ion–dependent and independent paths. From the kinetic data obtained at 25–55 °C, the specific rate constants and thermodynamic parameters have been computed.

Fast detection of triazine herbicides on a microfluidic chip using capillary electrophoresis pulse amperometric detection

We report simple and rapid capillary electrophoresis (CE) separation followed by in-channel pulsed amperometric detection (PAD) of three common triazine herbicides: simazine, atrazine and ametryn that are used to control broad leaf weeds and annual grasses. For their detection in soil and groundwater samples, a CE-PAD microfluidic chip was fabricated using standard photolithography methods. Cyclic voltammetry was conducted on these herbicides that exhibited a characteristic cathodic peak at -0.70V for simazine or atrazine and -0.80V for ametryn, without any anodic peak at reverse scan, indicating that the cathodic peaks were irreversible electron transfer processes. For effective CE-PAD separation of triazine complex, the capillary was filled with 1.5% agarose. The pulsed amperometric detection of these chemicals ensured better sensor response and low electrode fouling. The average electropherogram of simazine, atrazine and ametryn showed single peaks at 58, 66 and 74s, respectively at 20V/cm separation potential. A mixture of all three herbicides showed similar separated peaks. HPLC was also conducted in a soil spiked with these pollutants to compare the method. The results hold the promise of detecting triazines within a very short time.

Antioxidant activity and composition of propolis obtained by different methods of extraction

Ethanolic extracts of propolis obtained with different concentrations of propolis and made using hydrous ethanol with various water/ethanol contents were analyzed. The antioxidant action of the extracts was determined by free radical 1,1-diphenyl-2-picryl-hydrazyl (DPPH·) scavenging and by ferric reducing ability power (FRAP), using the ferric-tripyridyl triazine (Fe3+-TPTZ) complex. The total phenolic and flavonoid contents were also determined, and the electrospray ionization mass spectrometry spectra (ESI(-)-MS) of the extracts were acquired. The chemical composition of propolis extracts and their antioxidant activity were observed to vary with the concentration of propolis, and especially with the water/ethanol contents of the hydrous ethanol used for extraction. The antioxidant activity of the extracts was also found to be significantly dependent on these extraction parameters, as well as on the composition of the phenolic compounds and flavonoids. FRAP values showed, however, poor correlation with the flavonoid content

Different Routes for Amination of Platinum(II)-Bound Cyanoguanidine

The consecutive addition of AgSO(3)CF(3) (1 or 2 equiv) and cyanoguanidine (1 or 2 equiv, respectively) to the platinum(II) precursor [PtI(2)(tmeda)] leads to the cis-[PtI(tmeda){NCN=C(NH(2))(2)}](SO(3)CF(3)) (1.(SO(3)CF(3))) or cis-[Pt(tmeda){NCN=C(NH(2))(2)}(2)](SO(3)CF(3))(2) (2.(SO(3)CF(3))(2)) complexes. The reaction between 1.(SO(3)CF(3)) or 2.(SO(3)CF(3))(2) and the excess of R(2)NH (R = H, R(2) = C(5)H(10)) in EtOH gives the triazapentadiene compounds cis-[Pt(tmeda){NHC(NR(2))NC(NH(2))NH}](SO(3)CF(3)) (3.(SO(3)CF(3)) and 4.(SO(3)CF(3)), correspondingly). Protonation of these species results in cis-[Pt(tmeda){NHC(NR(2))NHC(NH(2))NH}](SO(3)CF(3))(2) ([3.H](SO(3)CF(3))(2) and [4.H](SO(3)CF(3))(2), respectively). The interaction of solid 2.(SO(3)CF(3))(2) and the gaseous RNH(2) (R = H, Me) leads to cis-[Pt(tmeda){NHC(NHR)NHC(NH(2))NH}(2)](SO(3)CF(3))(2) (5.(SO(3)CF(3))(2) and 6.(SO(3)CF(3))(2), respectively). Treatment of an acetone solution of 2.(SO(3)CF(3))(2) with an aqueous NH(3) or the reaction of 5.(SO(3)CF(3))(2) with Me(2)CO produces the triazine complex cis-{Pt(tmeda){NH=CNHC(Me)(2)}NHC(NH)(2)N}(2)(SO(3)CF(3))(2) (7.(SO(3)CF(3))(2)). The reaction of 5.(SO(3)CF(3))(2) with Me(2)CO also leads to 7.(SO(3)CF(3))(2). All new complexes were characterized by elemental analyses (C, H, N), electrospray ionization mass spectrometry, IR, and (1)H and (13)C NMR spectroscopies. The structures of 1.(SO(3)CF(3)), 2.(SO(3)CF(3))(2), 3.(SO(3)CF(3)), [4.H](SO(3)CF(3))(2), 5.(SO(3)CF(3))(2), and 7.(SO(3)CF(3))(2) were determined by single-crystal X-ray diffraction.

Antioxidant Properties of Peel and Pulp Hydro Extract in Ten Persian Pomegranate Cultivars

This study compares the antioxidant activity of ten different pomegranate cultivars grown in Iran using the ferric reducing power assay (FRAP assay), which is based on the reduction of a ferric-tripyridyl triazine complex to its ferrous, colored form in the presence of antioxidants. Aqueous solutions of known Fe(+2) concentration, in the range of 100-1000 micromol L(-1) were used for calibration. The results showed that among pulp and peel fractions the sour alac and sweet white peel cultivars had more FRAP value respectively. The pomegranate peel extract had markedly higher antioxidant capacity than the pulp extract. The peel extract of sweet white peel cultivar appeared to have more potential as a health supplement rich in natural antioxidants compared to the pulp and peel extracts of other pomegranate cultivars.

Anion−π and π−π Cooperative Interactions Regulating the Self-Assembly of Nitrate−Triazine−Triazine Complexes

We theoretically investigate the cooperative enhancement of the interactions between anions and electron-deficient aromatics by pi-pi stacking, focusing on the recent crystallographic observation of anion-pi-pi interactions in a synthesized coordination compound based on 1,3,5-triazine moieties. Using a combination of state-of-the-art dispersion-corrected density functional and quantum Monte Carlo calculations, we rationalize the unusual structural features observed in this nitrate-triazine-triazine complex. We show that the triazine rings are staggered and bent and slip with respect to each other with the nitrate bound off-center in a T-like configuration. Our results indicate that this pi-pi stacking is not simply enforced by the coordination of the triazines within the particular crystal structure but is regulated by cooperative anion-pi and pi-pi interactions. In the nitrate-triazine-triazine complex, this cooperative effect amounts to 6% of the total binding energy. Ways to further increase this energetic enhancement in the design of anion-host architectures are discussed.

Anion-pi interactions in a carousel copper(II)-triazine complex.

Unprecedented anion-pi interactions are revealed for the electron-poor triazine rings in [L2(CuCl)3][CuCl4]Cl (L = hexakis(pyridin-2-yl)-[1,3,5]-triazine-2,4,6-triamin), where both the chloride ion and a Cl atom of [CuCl4]2- are located approximately 3.15 A above the ring centroids, in excellent agreement with theoretical predictions for a Cl-...triazine complex. This confirms the importance of attractive anion-pi interactions for the supramolecular assembly of complexes with pi-electron-deficient heteroaromatics.

Absence of 1,3-metallotropic shifts in M(CO) 5 complexes of pyrimidine and 1,3,5-triazine (M=W, Mo, Cr)

M(CO) 5L complexes with M=W 0, Mo 0 and Cr 0 and L=pyrimidine and 1,3,5-triazine were prepared by photochemical generation from the parent M(CO) 6 complexes in acetone. All six complexes are not fluxional among available N-donor sites from room temperature up to ca. 60°C in CDCl 3, and do not undergo rapid exchange with external excess free ligand. Thus, as in the case of the W(CO) 5L complexes, a one-bond migration between N sites in a diazine occurs readily for pyridazine (e.g. a 1,2-metallotropic shift has been reported), but two-bond migrations for a 1,3-metallotropic shift is not seen with pyrimidine or triazine, just as the three-bond migration for a 1,4-metallotropic shift was not observed previously for the pyrazine complexes. The decomposition processes of the M(CO) 5L complexes in CDCl 3 with pyrazines is known to follow the order Cr (minutes lifetime)⪢Mo (several hours)>W (days to weeks duration), but for the pyrimidine and 1,3,5-triazine complexes Cr and W are of comparable stability (stable for 1–2 weeks), and more so than the Mo analogue (stable for about 7–8 h). 1H NMR data on all six complexes show that protons α to the site of metallation are shifted downfield by 0.27–0.36 ppm compared to the free ligand. The magnitude of Δ δ for the effect of metals on the chemical shift follow the order W>Mo>Cr. The more remote H4 protons of pyrimidine or triazine exhibit the smallest downfield shift upon metallation by the M(CO) 5 moiety. For the Cr(CO) 5 derivative the H4 proton of pyrimidine and H5 of triazine are shifted upfield. The upfield shift effect for the H5, near absence of a net effect for H4 of pyrimidine, and the upfield shift observed for H4 of the triazine complex of the Cr series are attributed mainly to a strong resonance component with dπ back-donation for the Cr derivative, as well as a possible TIP influence on the chemical shift parameter, contributions that are attenuated for the Mo and W complexes with higher energy excited states. No evidence for η 2-type coordination for these d 6 complexes was obtained in contrast to Ru(II) d 6 chemical relatives which adopt η 2 coordination to pyrimidines.