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Three novel asymmetric ligands, 3-(pyridine-2-yl)-5,6-diphenyl-as-triazine (pdtb), 3-(pyridine-2-yl)-as-triazino[5,6-f]acenaphthylene (pdta) and 3-(pyridine-2-yl)-as-triazino[5,6-f]phenanthroline (pdtp) and their cobalt(III) complexes have been synthesized and characterized. Binding of the three complexes with calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods, viscosity, cyclic voltammetry, and electrophoresis measurements. The experimental results indicate that the size and shape of the intercalated ligand have a marked effect on the binding affinity of complexes to CT-DNA. Complexes 2 and 3 have also been found to promote cleavage of plasmid pBR322 DNA from the supercoiled form I to the open circular form II upon irradiation. [Copyright &y& Elsevier]

Two asymmetric tridentate copper(II) complexes, [Cu(dppt)Cl2] · 0.25H2O (1) (dppt=3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazine) and [Cu(pta)Cl2] (2) (pta=3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]acenaphthylene), have been prepared and characterized by elemental analysis, IR and Fast atomic bombardment mass spectra. Complex 1 has also been structurally characterized. The complexes exist as distorted square pyramid with five co-ordination sites occupied by the tridentate ligand and the two chlorine anions. DNA interaction studies suggest that the ligand planarity of the complex has a significant effect on DNA binding affinity increasing in the order [Cu(dppt)Cl2] < [Cu(pta)Cl2]. In the presence of ascorbate or glutathione, the two complexes are found to cause significant cleavage of double-strand pBR 322 DNA and [Cu(pta)Cl2] exhibited the higher cleaving efficiency. [Copyright &y& Elsevier]

Selenium isotopes are becoming an important paleoenvironmental proxy. However, few studies have focused on the behavior of Se isotopes during oxidative weathering. In this paper, a comprehensive set of Se isotopic composition and concentration data were collected from the weathering profiles of Se-rich shales of the Permian Maokou Formation in Yutangba and Shadi, China to investigate Se isotopic fractionation and Se enrichment during weathering processes. The δ82/76Se in fresh shales (148±118mg/kg Se, 1SD, n =40) from Shadi and Yutangba drill cores varies from −1.69‰ to 1.74‰ with an average of 0.40±0.71‰ (1SD, n =40), consistent with the range in other Phanerozoic shales, suggesting that Se isotopes are not strongly fractionated during Se sequestration in the primary sedimentary environment. However, the strongly weathered Se-rich shales from Shadi and Yutangba profiles are isotopically lighter with average δ82/76Se values of −1.96±1.08‰ (1SD, n =5) and −1.08±1.83‰ (1SD, n =23), respectively. These data suggest that Se isotopes can be fractionated during oxidation and reduction processes associated with weathering, with heavier isotopes removed preferentially during oxidative weathering of shales. Such a shift, if found to be a global phenomenon, would have implications for models of the global Se cycle and interpretation of Se isotope data from past biogeochemical regimes. Locally altered shales exposed in a quarry at Yutangba are extremely enriched in Se with 1642±1505mg/kg (1SD, n =45), approximately 10 times greater than that in unaltered drill core samples. These rocks display very strong variation in δ82/76Se over short distances, with a single 60cm transect showing the most strongly negative and positive δ82/76Se values (−14.20‰ to +11.37‰) observed to date in natural samples. This suggests that Se has undergone multiple cycles of oxidation, mobilization, and re-reduction, resulting in a Se-rich redox front that has migrated downward through the organic-rich shales over time. δ82/76Se values vary sharply over distances as small as 10cm, indicating that Se redox conditions change strongly with position and are controlled by fractures and rock layering. Our data and a simple conceptual model suggest that zones of increased permeability that are accessed first by infiltrating waters are isotopically light, whereas less accessible zones are heavy. Repeated redox cycling accentuates this pattern. Furthermore, the average δ82/76Se in Se-rich shales at the Yutangba weathering system is 0.45±5.77‰ (1SD, n =39), identical with that (0.40±0.71‰) in fresh shales from same locality, implying that Se released by weathering accumulates in the redox front with little loss. The strong Se isotopic fractionation occurring in the redox front implies that Se isotopes can be extensively used in tracing geochemical processes of Se in groundwater system, especially related to fractures. [ABSTRACT FROM AUTHOR]

Abstract: In order to automatically identify fatty acids in plant seed oils, a method was developed to search all saturated fatty acid methyl esters in the sample, subsequently calculate the ECL value of each fatty acid, and finally identify the molecular structure for each component by comparing the ECL of the interest and that in the customised database. Our method was applied to analyse the fatty acid composition of Eucommia ulmoides seed oil. The results show that major polyunsaturated fatty acids are α-linolenic acid (56.5093% of total fatty acids, TFAs) and linolelaidic acid (12.6563% of TFAs). Meanwhile, the main monounsaturated fatty acid is oleic acid whose percentage in the TFAs is 15.8008. Palmitic acid and steartic acid are the dominant saturated fatty acids representing 9.8165% and 2.5942% of TFAs, respectively. The UFA/SFA ratio (6.57) is higher than the recommended value (3) by nutritionists. [Copyright &y& Elsevier]

Abstract: Three new phenothiazine-corrole dyads were prepared by the reaction of phenothiazine-10-carbonyl chloride and mono-hydroxyl triaryl corrole in the presence of DBU. As compared to corrole monomer, these phenothiazine-corrole dyads exhibit significant enhanced DNA photocleavage activity as compared to corrole monomer precursors. [Copyright &y& Elsevier]