Syntheses,crystal structures,and catalytic properties of three zinc(Ⅱ),cobalt(Ⅱ)and nickel(Ⅱ)coordination polymers constructed from 5⁃(4⁃carboxyphenoxy)nicotinic acid

Three zinc(Ⅱ),cobalt(Ⅱ),and nickel(Ⅱ)coordination polymers,namely[Zn(μ^(3-)cpna)(μ-dpea)_(0.5)]_(n)(1),[Co(μ^(3-)cpna)(μ-dpey)_(0.5)]_(n)(2),and[Ni(μ^(3-)cpna)(μ-dpey)_(0.5)(H_(2)O)]_(n)(3),have been constructed hydrothermally using H_(2)cpna(5-(4-carboxyphenoxy)nicotinic acid),dpea(1,2-di(4-pyridyl)ethane),dpey(1,2-di(4-pyridyl)ethylene),and zinc,cobalt,and nickel chlorides at 160℃.The products were isolated as stable crystalline solids and were characterized by IR spectra,elemental analyses,thermogravimetric analyses,and single-crystal X-ray diffraction analyses.Single-crystal X-ray diffraction analyses revealed that three compounds crystallize in the triclinic system,space group P1.Compounds 1-3 show 2D layer structures.The catalytic activities in the Knoevenagel condensation reaction of these compounds were investigated.Compounds 1 and 2 exhibit effective catalytic activities in the Knoevenagel condensa-tion reaction at room temperature.For this reaction,various parameters were optimized,followed by the investiga-tion of the substrate scope.CCDC:2335676,1;2335677,2;2335678,3.

CaCl2对低盐罗非鱼肌球蛋白凝胶持水性和微观结构的影响

以罗非鱼(Oreochromis niloticus)肌球蛋白为研究对象,在不同盐浓度(1,50,150,600 mmol/L NaCl)下,考察适量添加CaCl2对肌球蛋白热诱导凝胶持水性、微观结构及化学作用力的影响。结果表明,低盐浓度(1~150 mmol/L NaCl)下,热诱导肌球蛋白纤丝迅速聚集,体系呈弱的不透明凝胶,链状交联的凝胶网络结构粗糙、孔隙极大,持水性低,疏水相互作用是维持凝胶的主要化学作用力。当CaCl2添加量为10 mmol/L时,有利于凝胶化过程中肌球蛋白分子结构部分展开,氢键相互作用减弱,α-螺旋部分转化成β-折叠,分子间二硫交联作用增强(P<0.05),形成致密有序的三维网状结构,持水性显著提高(P<0.05),且1 mmol/L NaCl浓度下的改善效果更明显。因此,添加适量的CaCl2可有效改善低盐条件下肌球蛋白的凝胶性能。