稀土配位聚合物_Pr_2_5_pdc_OH_省略__2O_2_H_2O的合成_结

第48卷　第3期吉林大学学报(理学版)Vol .48　No .3　2010年5月Journal of J ilin University (Science Editi on )May 2010稀土配位聚合物[Pr(2,52pdc)(O H)(H 2O )2]・H 2O的合成、结构及热稳定性谢　妍1,邢永恒1,王　卓1,赵海燕1,王春光1,曾小庆2,葛茂发2(1.辽宁师范大学化学化工学院,辽宁大连116029;2.中国科学院化学研究所,北京100190)摘要:采用水热方法合成一种新型的稀土有机配合物[Pr (2,52pdc )(OH )(H 2O )2]・H 2O ,通过元素分析、红外光谱及X 射线衍射方法对该配合物进行结构表征.结构分析表明:标题配合物属于单斜晶系;P 21/c 空间群;晶胞参数a =0.9350(4)n m ,b =1.6158(6)n m ,c =018309(3)nm ,α=γ=90.000°,β=94.078(7)°,V =1.2521(9)nm 3,Z =4.配合物中镨离子通过μ22OH 桥连接形成双核构筑单元,进一步通过2,52pdc 中的羧基氧原子连接形成三维结构.关键词:镨(Ⅲ)配位聚合物;2,52吡啶二羧酸;三维结构;水热合成中图分类号:O611 文献标志码:A 文章编号:167125489(2010)0320495204Cryst al Structure and Ther mal St ability of a New Lanthan i deCoordi n ati on Poly mer [Pr(2,52pdc)(OH)(H 2O )2]・H 2OX IE Yan 1,X ING Yong 2heng 1,WANG Zhuo 1,ZHAO Hai 2yan 1,WANG Chun 2guang 1,ZE NG Xiao 2qing 2,GE Mao 2fa 2(1.College of Che m istry and Che m ical Engineering,L iaoning N or m al U niversity,D alian 116029,L iaoning Province,China;2.Institute of Che m istry,Chinese A cade m y of Sciences,B eijing 100190,China )Ab s trac t:A ne w lanthanide 2organic fra me work [Pr (2,52pdc )(OH )(H 2O )2]・H 2O was synthesized under hydr other mal conditi ons and characterized by ele mental analysis,I R s pectr ometry and single crystal X 2ray diffracti on .X 2ray diffracti on analyses reveal that the title comp lex was crystallized in a monoclinic s pace gr oup P 21/c ,with a =0.9350(4)nm ,b =1.6158(6)nm ,c =0.8309(3)nm ,α=γ=90.000°,β=94.078(7)°,V =1.2521(9)n m 3,Z =4.The co mp lex possesses binuclear units constructed via OH-bridging,and the binuclear units are further connected by carboxyl oxygen at om s of 2,52pdc ligands t o for m a 3D fra me work .Key wo rd s:p raseody m ium (Ⅲ)coordinati on poly mer;pyridine 22,52dicarboxylic acid;3D structure;hydr other mal synthesis收稿日期:2009207214.作者简介:谢　妍(1982—),女,汉族,硕士研究生,从事生物无机与无机药物配位化学的研究,E 2mail:xiejing1682000@.通讯作者:邢永恒(1964—),男,汉族,博士,教授,从事生物无机与无机药物配位化学的研究,E 2mail:yhxing2000@yahoo .com.基金项目:国家自然科学基金(批准号:20771051)和辽宁省教育厅2007年创新团队计划项目(批准号:2007T093).近年来,新的金属2有机配合物以其独特的性质以及在超分子化学领域中潜在的应用而受到研究人员的广泛关注[1],其中,配位数高的f 区镧系元素因其配位后性质独特而常被用于合成多功能的稀土2有机配合物[2].目前,以多羧酸为配体的金属2有机配位聚合物由于结构特殊,在催化、分离、气体储存和发光等方面展现了广阔的应用前景[3].对这些配合物的研究发现,含有OH 桥的配合物结构新而复杂但报道却较少.文献中已报道的含有OH 桥的稀土配合物可分为以下四类:(1)含μ22OH 的稀土配合物,如[Ln 3(μ2OH )4(2,52pydc )(2,52Hpydc )3(H 2O )4]n (Ln =Gd,Dy,Er,Eu,S m ,Yb,Y )[4],[Tb 2(D inic )2(phen )2(OH )2(H 2O )2]n ・3n H 2O [5]等;(2)含μ32OH 的稀土配合物,如[Ln 2(pdc )2(OH )2(H 2O )2]・H 2O (Ln =Eu,Tb )[6],[Ln 3(bdc )3.5(OH )2(H 2O )2]・H 2O (Ln =Y,Yb,Er )[7],[Ln 5(μ32OH )(oba )7(H 2O )2]n ・0.5n H 2O (Ln =Eu,Ho )[8],[Ln 2(Suc )0.5(Bc )3(OH )2](Ln =Tb,S m ,Pr )[9]等;(3)含μ42OH 的稀土配合物,如[Eu 5(μ42OH )(μ32OH )4]10+[10]等;(4)含μ52OH 的稀土配合物,如Ln 5(2,62Nds )3(OH )9(H 2O )4(H 2O )2,LnPF 23(Ln =Nd,Eu )[11]等.在这些构筑稀土2有机配合物的配体中,吡啶二羧酸配位模式多样而复杂[12],对2,52吡啶二羧酸的配位模式已有报道[2].为了进一步比较和探讨吡啶二羧酸与稀土配位模式的多样性,本文首次合成一个含有μ22OH 和2,52吡啶二羧酸(H 2pdc =pyridine 22,52dicarboxylic acid )为配体的3D 结构稀土配合物[Pr (2,52pdc )(OH )(H 2O )2]・H 2O,并研究其晶体结构.1　实　验1.1　试剂与仪器稀土氯化物Pr Cl 3・6H 2O:在加热条件下,将稀土金属的氧化物(质量分数为99.9%的Pr 2O 3)经盐酸溶解后,100℃蒸发,再冷却至室温.所用其他试剂均为分析纯.元素分析采用Yanaco CHN CORDER MT 26型元素分析仪测定;红外光谱用JASCO FT/I R 2480型傅里叶变换红外光谱仪(K B r 压片,200～4000c m -1)测定;X 射线粉末衍射采用B ruker Advance 2D8型X 射线粉末衍射仪测定;热分析数据用Perkin El m er D ia mond TG/DT A 型热分析仪测定.1.2　标题配合物的合成将Pr Cl 3・6H 2O (0.2726g )、2,52吡啶二羧酸(0.0960g )、戊二酸(0.0850g )和2,2′2联吡啶(0.1020g )混合于烧杯中,加10mL 蒸馏水,搅拌,用乙二胺调节pH 值至6.0.反应3h 后将混合物装入带有聚四氟乙烯内衬的不锈钢反应釜中,在160℃烘箱内反应3d 后取出,缓慢冷却至室温.过滤,并用蒸馏水洗涤产物,室温干燥,得到绿色颗粒状晶体0.17g .产率:65.18%(以Pr 为基准).元素分析C 7H 10NO 8Pr (%,计算值):C 27.18(27.27),H 2.80(2.65),N 3.58(3.71).I R (K B r 压片,ν(c m -1)):3342,1588,1393,1367,1279,1180,1152,1031,945,916,874,825,766,695,644,522,384.1.3　标题配合物的晶体结构测定和热分析测定选取大小为0.078mm ×0.044mm ×0.039mm 的晶体置于B ruker S MART APEX ⅡCCD 型X 射线衍射仪上,以Mo Kα(λ=0.071073n m )射线为辐射源,采用I P 面探器,以ω扫描方式收集衍射数据,全部反射数据经LP 因子和经验吸收校正.晶体结构采用直接法解出,非氢原子坐标和各向异性温度因子采用全矩阵最小二乘法修正,晶体结构的解析和精修用SHELX 297[13]程序完成.该配合物是单斜晶系,P 21/c 空间群,晶体学参数为:a =0.9350(4)n m ,b =1.6158(6)n m ,c =0.8309(3)n m ,α=γ=90.000°,β=94.078(7)°,V =1.2521(9)n m 3,Z =4.最后的一致性因子为R 1=0.0553,wR 2=0.1291;晶体数据存储号(CCDC ):713798.热分析测定实验条件:静态氮气气氛;升温速率:10℃/m in;温度范围:50～1000℃;样品用量:2.927mg .2　结果与讨论2.1　X 射线粉末衍射标题配合物的粉末X 射线衍射谱图与拟合的XRD 谱图吻合,如图1所示,表明该配合物为纯相.2.2　标题配合物的晶体结构标题配合物的分子结构如图2所示.由图2可见,配合物的不对称结构单元中含有1个Pr Ⅲ离子,694 吉林大学学报(理学版) 第48卷　它与来自4个2,52pdc 中的4个氧原子、来自1个2,52pdc 中的1个氮原子,2个水分子中的2个氧原子及2个OH -形成九配位的多面体结构.每个2,52pdc 都作为μ42桥连接4个Pr Ⅲ离子,其中的氮原子和2位羧基中的氧原子以μ22η2:η1的桥配模式与Pr Ⅲ螯合,而且5位羧基中的氧原子以μ22η1:η1的桥配模式与Pr Ⅲ离子配位,配体的这种配位模式文献[14]中有报道.Pr —O (OH )键长范围在01248(2)～01255(2)n m ,比含有μ32OH 的配合物[Ln 2(pdc )2(OH )2(H 2O )2]・H 2O (0.236(1)～0.247(4)nm )键长略长,Pr —O (pdc )的平均键长为0.244(2)n m ,比文献[15]报道的Pr —O 键长略短.标题配合物的结构如图3所示.在分子结构中,等效的2个Pr Ⅲ离子通过μ22OH 和2个2,52pdc 中的5位上的羧基桥连接(图3(A ))成一个双核构筑单元,构筑单元间通过μ22η1:η1的羧基桥连接形成一维链状结构(图3(B )).在bc 面上,链与链间通过μ22η1:η1桥配模式的羧基桥连接形成二维层状结构(图3(C )).最终,层与层间进一步通过2,52pdc 吡啶环交替连接形成了三维的骨架结构(图3(D )).分析表明,由2,52吡啶二羧酸和OH -桥连的稀土配合物可以形成微孔网络结构,而这种金属2有机框架结构在发光材料、吸附剂、清洁剂以及添加剂等方面可能具有潜在的应用价值[526].图1　标题配合物模拟(a)与实验(b)的XR D 衍射谱F i g .1　S i m ul a ted (a)and exper i m en t a l (b)X 2rayd i ffracti on pa ttern s of title co mplex 图2　标题配合物的双核单元结构F i g .2　B i n uclear un it of the title co mplex图3　标题配合物从双核单元到三维网状框架的结构F i g .3　Structures of b i n uclear un its,1D 2cha i n ,2D 2l ayer and 3D net fram ework of title co m pound2.3　标题配合物的热分解过程图4为标题配合物的TG 2DTG 2DT A 曲线.由图4可见,配合物在50～1000℃内失重分两阶段:第一阶段失重的温度范围为86～166℃,失重率为4.62%,与失去1个结晶水的理论失重值4.77%基本吻合,在DT A 曲线上的152℃处有1个很弱的吸热峰,表明配合物在此阶段的热分解是一个吸热过程;第二阶段失重的温度范围为166～847℃,失重率为37.57%,与失去2个配位H 2O 、1个OH 和2个CO 2理论失重值37.39%吻合,这种失重过程与文献[6]的报道相似;在DT A 曲线上,503℃处出现一个很强的吸热峰,表明在此阶段是吸热过程.在847～1000℃内,TG 曲线趋于平缓,无明显下降趋势,且逐渐趋于稳定,表明该配合物骨架已经塌陷,形成稀土氧化物并且有一定量的积碳形成.794　第3期 谢　妍,等:稀土配位聚合物Pr (2,52pdc )(OH )(H 2O )2]・H 2O 的合成、结构及热稳定性 图4　标题配合物的TG 2D TG 2D TA 曲线(插图为D TA 曲线)F i g .4　TG 2D TG 2D TA curves of title co m plex (the i n sert chart:D TA curve)参考文献[1]　L I U Cai 2m ing,ZHANG De 2qing,Z HU Dao 2ben .I n Situ Hydr other mal Decarboxylati on f or Unp recedented Three 2D i m ensi onal 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