Menelaou M, Konstantopai A, Mateescu C, Zhao H, Drouza C, Lalioti N, Salifoglou A
Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
Inorg Chem. 2009 Sep 7;48(17):8092-105. doi: 10.1021/ic801500x.
Cobalt(II) is an essential metal ion, which can react with biologically relevant substrates in aqueous media, affording discrete soluble forms. D-(-)-quinic acid is a representative metal ion binder, capable of promoting reactions with Co(II) under pH-specific conditions, leading to the isolation of the new species K[Co(C(7)H(11)O(6))(3)] x 3 CH(3)CH(2)OH (1), Na[Co(C(7)H(11)O(6))(3)] x 3 CH(3)CH(2)OH x 2.25 H(2)O (2), and [Co(C(7)H(11)O(6))(2)(H(2)O)(2)] x 3 H(2)O (3). Compounds 1-3 were characterized by elemental analysis, spectroscopic techniques (Fourier-transform infrared, UV-visible, electron paramagnetic resonance (EPR), electrospray ionization mass spectrometry), magnetic studies, and X-ray crystallography. Compound 1 crystallizes in the cubic space group P2(1)3, with a = 15.3148(19) A, V = 3592.0(8) A(3), and Z = 4. Compound 2 crystallizes in the orthorhombic space group P2(1)2(1)2(1), with a = 14.9414(8) A, b = 15.9918(9) A, c = 16.0381(9) A, V = 3832.1(4) A(3), and Z = 4. Compound 3 crystallizes in the monoclinic space group P2(1)/m, with a = 13.2198(10) A, b = 5.8004(6) A, c = 15.3470(12) A, beta = 108.430(7), V = 1116.45(17) A(3), and Z = 4. The lattices in 1-3 reveal the presence of mononuclear Co(II) units bound exclusively to quinate (1 and 2) or quinate and water ligands (3), thus projecting the unique chemical reactivity in each investigated system and suggesting that 3 is an intermediate in the synthetic pathway leading to 1 and 2. The octahedral sites of Co(II) are occupied by oxygens, thereby reflecting the nature of interactions between the divalent metal ion and quinic acid. The magnetic and EPR data on 1 and 3 support the presence of a high-spin octahedral Co(II) in an oxygen environment, having a ground state with an effective spin of S = 1/2. The significance of 3 is further reflected into the aqueous speciation of the binary Co(II)-quinic acid system, in which 3 appears as a competent participant linked to the solid state species 1. The physicochemical profiles of 1-3, in the solid state and in solution, earmark the importance of aqueous structural speciation, which projects chemical reactivity pathways in the binary Co(II)-quinate system, involving soluble Co(II) forms emerging through interactions with low molecular mass O-containing physiological substrates, such as quinic acid.
钴（II）是一种必需的金属离子，它能在水介质中与具有生物学相关性的底物发生反应，生成离散的可溶形式。D -（-）-奎尼酸是一种典型的金属离子结合剂，能够在特定pH条件下促进与Co（II）的反应，从而分离出新型化合物K[Co(C₇H₁₁O₆)₃]·3CH₃CH₂OH（1）、Na[Co(C₇H₁₁O₆)₃]·3CH₃CH₂OH·2.25H₂O（2）和[Co(C₇H₁₁O₆)₂(H₂O)₂]·3H₂O（3）。通过元素分析、光谱技术（傅里叶变换红外光谱、紫外可见光谱、电子顺磁共振（EPR）、电喷雾电离质谱）、磁性研究和X射线晶体学对化合物1 - 3进行了表征。化合物1结晶于立方空间群P2₁3，a = 15.3148(19) Å，V = 3592.0(8) ų，Z = 4。化合物2结晶于正交空间群P2₁2₁2₁，a = 14.9414(8) Å，b = 15.9918(9) Å，c = 16.0381(9) Å，V = 3832.1(4) ų，Z = 4。化合物3结晶于单斜空间群P2₁/m，a = 13.2198(10) Å，b = 5.8004(6) Å，c = 15.3470(12) Å，β = 108.430(7)，V = 1116.45(17) ų，Z = 4。1 - 3中的晶格显示存在仅与奎尼酸（1和2）或奎尼酸和水配体（3）结合的单核Co（II）单元，从而突出了每个研究体系中独特的化学反应性，并表明3是导致1和2的合成途径中的中间体。Co（II）的八面体配位位点被氧占据，从而反映了二价金属离子与奎尼酸之间相互作用的性质。关于1和3的磁性和EPR数据支持在氧环境中存在高自旋八面体Co（II），其基态有效自旋为S = 1/2。3的重要性进一步体现在二元Co（II）-奎尼酸体系的水相形态中，其中3表现为与固态物种1相关的有效参与者。1 - 3在固态和溶液中的物理化学特征表明了水相结构形态的重要性，它在二元Co（II）-奎尼酸盐体系中规划了化学反应途径，涉及通过与低分子量含氧化生理底物（如奎尼酸）相互作用而出现的可溶性Co（II）形式。
