一种链状甘氨酸超分子材料(C_(2)H_(6)NO_(2))+(18-crown-6)[I]-(H_(2)O)_(2)的合成与表征

Synthesis,and characterization of a chain glycine supramolecular material(C_(2)H_(6)NO_(2))+(18-crown-6)[I]-(H_(2)O)_(2)

以18-冠醚-6为主体、甘氨酸为客体、无机酸为电荷抗衡离子,水和乙醇混合溶剂,通过室温蒸发法获得杂化型氨基酸超分子晶体材料:(C_(2)H_(6)NO_(2))+(18-crown-6)[I]-(H_(2)O)_(2)。并采用红外光谱(IR)、X-射线单晶衍射、X-射线粉末衍射(XRD)、热重(TG)、介电等多种方式对晶体材料进行表征。单晶结构解析显示在低温(100 K)和室温(293 K)条件下,该化合物的空间群属于三斜晶系(P 2_(1)/n)。质子化的甘氨酸离子的-NH_(3)^(+基)团,通过N—H…O氢键相互作用镶嵌入18-冠醚-6环内,形成一种新型转子-定子式结构,并以O—H…O、O—H…I氢键作用,在b轴方向上形成一维链状超分子结构。随着温度升高,甘氨酸分子发生明显的动态摆动,导致晶体结构a轴方向上的介电常数在200 K和260 K附近连续产生两处明显的阶梯状介电异常。

The hybrid amino acid supramolecular crystal material,(C_(2)H_(6)NO_(2))+(18-crown-6)[I]-(H_(2)O)_(2)was synthesized by natural evaporation at room temperature in ethanol aqueous solution with 18-crown-6 as the main body,glycine as the guest and inorganic acid as the charge counterweight.The crystal material was characterized by infrared analysis(IR),X-ray single crystal diffraction,X-ray powder diffraction,thermogravimetric analysis(TG),dielectric constant measurements and so on.The analysis of single crystal structure shows that the space group of the compound belongs to triclinic crystal system,P 2_(1)/n space group,at low temperature(100 K)and room temperature(293 K).The proton-NH_(3)^(+)group of glycine ion is embedded into the 18-crown-6 ring through N—H…O hydrogen-bonding interaction,forming a new rotor-stator structure.In addition,a one-dimensional chain supramolecular structure was formed through O—H…O、O—H…I hydrogen bonds along the b-axis.The glycine molecule occurred obvious dynamic oscillation with the increase of temperature,leading to the dielectric constant along the a-axis of the crystal structure continuously generates two distinct step-like dielectric anomalies in the a-axis direction near 200 K and 260 K.