新型大环冠醚基杂化型晶体材料:分子结构和介电性质

A Novel Hybrid Crystalline Material Based on 18-Crown-6:Molecular Structure and Dielectric Properties

4-氨基丁酸(4-aminobutyric acid,GABA)质子化的氨基基团与18-冠-6醚(18-crown-6)分子中六个氧原子通过N—H…O氢键相互作用,形成超分子阳离子结构,再与高碘酸根IO4-结合形成新型晶体材料[(GABAH+)(18-crown-6)(IO4-)](1)。通过元素分析、红外光谱(IR)、热重分析(TG)、单晶结构X衍射(100K和296K)和变温-介电常数测试等对所获得晶体材料进行结构分析。测试结果显示该晶体结构为单斜晶系,空间群为P21/c,室温条件下a=1.008 41(11)nm,b=2.457 3(3)nm,c=0.964 73(10)nm,α=90.00°,β=99.060(2)°,γ=90.00°,V=2.360 8(4)nm3,Z=4,Dcalc=1.574g/cm,Rint=0.036 2,WR (all data)=0.085 9。高碘酸根IO4-填充在超分子阳离子[(GABAH+)(18-crown-6)]所形成的空隙中,与4-氨基丁酸的羧酸根形成O—H…O氢键。变温-介电常数显示化合物1在280K时,出现明显的介电异常,同时存在25K的热滞现象,表明该晶体为介电新型功能材料。

The[(GABAH+)(18-crown-6)](4-Aminobutyric acid,GABA)adduct in the supramolecular cation was formed through intermolecular N—H…O hydrogen bonding interaction between the nitrogenatoms of NH3+moiety and six-oxygen atoms of 18-crown-6.The supramolecular cations interacted with IO4-anions through molecular self-assembly so as to form a new crystal of[(GABAH+)(18-crown-6)-(IO4-)](1).The compound was characterized by elemental analysis,infrared spectra(IR)spectroscopy,thermogravimetric analysis(TG),temperature-and frequency-dependence dielectric measurements and the crystal structure was determined by single-crystal X-ray diffraction.The results show that crystal 1 belongs to the monoclinic system with the space group P21/c and the cell parameters of a=1.008 41(11)nm,b=2.457 3(3)nm,c=0.964 73(10)nm,α=90.00°,β=99.060(2)°,γ=90.00°,V=2.360 8(4)nm3,Z=4,Dcalc=1.574 g/cm,Rint=0.036 2,WR(all data)=0.085 9.The IO4-anions interact with COO-anion of 4-aminobutyric acid so as to be filled in the space of the supramolecular cations via strong O—H…O hydrogen bonding interaction.Temperature-dependent dielectric constant of compound 1 shows distinct dielectric anomalies at 280 K.There is also a 25 Kof thermal hysteresis,which suggests the compounds can be used as dielectric functional material.