Priya Vadhana K T, Parveen S, Ushadevi B, Selvakumar R, Sangeetha S, Vairam S
Chemistry, Government College of Technology, Thadagam Road, Coimbatore, Tamilnadu 641 013, India.
Science and Humanities, Dr Mahalingam College of Engineering and Technology, Makkinampatti, Pollachi, Tamilnadu 642 003, India.
Acta Crystallogr C Struct Chem. 2019 Aug 1;75(Pt 8):1091-1101. doi: 10.1107/S2053229619009082. Epub 2019 Jul 9.
A new set of differently hydrated barium and strontium squarates, namely poly[[triaqua(μ-1,2-dioxocyclobut-3-ene-1,2-diolato)barium] monohydrate], {[Ba(CO)(HO)]·HO} (1), poly[[diaqua(μ-1,2-dioxocyclobut-3-ene-1,2-diolato)strontium] monohydrate], {[Sr(CO)(HO)]·HO} (2), and poly[[triaqua(μ-1,2-dioxocyclobut-3-ene-1,2-diolato)barium/strontium(0.85/0.15)] monohydrate], {[BaSr(CO)(HO)]·HO} (3), is reported. The study of their crystal structures indicates that all the complexes crystallize in the triclinic space group P-1. Complexes 1 and 3 have a rare combination of squarate units coordinated through monodentate O atoms to two different metal atoms and through two bidentate O atoms to three different metal atoms. Furthermore, they have three coordinated water molecules to give a coordination number of nine. The squarate ligands in complex 2 exhibit two different coordination modes: (i) monodentate O atoms coordinated to four different Sr atoms and (ii) two monodentate O atoms coordinated to two different metal atoms with the other two O atoms bidentate to four different Sr atoms. All the compounds decompose to give the respective carbonates when heated to 800 °C, as evidenced by thermogravimetry/differential thermal analysis (TG-DTA), which are clusters of nanoparticles. Complexes 1 and 3 show additional endothermic peaks at 811 and 820 °C, respectively, indicating the phase transition of BaCO from an orthorhombic (α-Pmcn) to a trigonal phase (β-R3m). All three complexes have significant DNA-binding constants, ranging from 2.45 × 10 to 9.41 × 10 M against EB-CT (ethidium bromide-calf thymus) DNA and protein binding constants ranging from 1.1 × 10 to 8.6 × 10 with bovine serum albumin. The in vitro cytotoxicity of the complexes is indicated by the IC values, which range from 128.8 to 261.3 µg ml. Complex 3 shows better BSA binding, antioxidant activity against the DPPH radical and cytotoxicity than complexes 1 and 2.
报道了一组新的不同水合状态的方形酸钡和方形酸锶，即聚[[三水合（μ-1,2-二氧代环丁-3-烯-1,2-二醇根）钡]一水合物]，{[Ba(C₂O₄)(H₂O)₃]·H₂O} (1)、聚[[二水合（μ-1,2-二氧代环丁-3-烯-1,2-二醇根）锶]一水合物]，{[Sr(C₂O₄)(H₂O)₂]·H₂O} (2) 以及聚[[三水合（μ-1,2-二氧代环丁-3-烯-1,2-二醇根）钡/锶(0.85/0.15)]一水合物]，{[Ba₀.₈₅Sr₀.₁₅(C₂O₄)(H₂O)₃]·H₂O} (3)。对它们晶体结构的研究表明，所有配合物均结晶于三斜晶系空间群P-1中。配合物1和3具有一种罕见的方形酸根单元组合方式，即通过单齿O原子与两个不同金属原子配位，以及通过两个双齿O原子与三个不同金属原子配位。此外，它们有三个配位水分子，配位数为9。配合物2中的方形酸根配体表现出两种不同的配位模式：(i) 单齿O原子与四个不同的Sr原子配位；(ii) 两个单齿O原子与两个不同金属原子配位，另外两个O原子以双齿形式与四个不同的Sr原子配位。所有化合物在加热至800 °C时都会分解生成各自的碳酸盐，热重分析/差示热分析（TG-DTA）证明了这一点，分解产物为纳米颗粒簇。配合物1和3分别在811和820 °C出现额外的吸热峰，表明BaCO₃从正交晶系（α-Pmcn）向三方晶系（β-R3m）发生相变。所有三种配合物都有显著的DNA结合常数，相对于EB-CT（溴化乙锭-小牛胸腺）DNA，其范围为2.45 × 10⁵至9.41 × 10⁵ M，与牛血清白蛋白的蛋白质结合常数范围为1.1 × 10⁵至8.6 × 10⁵。配合物的体外细胞毒性由IC₅₀值表示，其范围为128.8至261.3 µg ml⁻¹。配合物3在与牛血清白蛋白结合、对DPPH自由基的抗氧化活性以及细胞毒性方面表现优于配合物1和2。
