李秀梅,王志濤,牛艷玲,黃艷菊
(通化師范學(xué)院 化學(xué)學(xué)院,吉林 通化 134002)
由于配位聚合物有著迷人的拓?fù)鋵W(xué)結(jié)構(gòu)和特殊的物理、化學(xué)性質(zhì),使得它們?cè)谥骺腕w化學(xué)、磁性材料、超導(dǎo)材料、非線性光學(xué)材料、分子吸收、催化材料及醫(yī)藥等諸多方面都表現(xiàn)出極好的應(yīng)用前景,從而吸引了國(guó)內(nèi)外許多學(xué)者投入到這一領(lǐng)域進(jìn)行研究[1-6].到現(xiàn)在為止,人們已經(jīng)合成了許多配位聚合物,并研究了其性質(zhì).在已報(bào)道的文章中,由于銅離子容易同時(shí)與多個(gè)相同的或不同的配體配位,而且其配位數(shù)也復(fù)雜多變,得到的配位聚合物又常常具有新奇的結(jié)構(gòu)與奇特的性質(zhì),故Cu(II)-配位聚合物的研究引起了人們的普遍關(guān)注,并取得了一系列的研究成果[7-10].
本文利用H2NIPH和phen為配體,與Ni(OAc)2·4H2O在150℃下反應(yīng)合成了一種配位聚合物[Ni(NIPH)(phen)(H2O)0.5]2n,并對(duì)其進(jìn)行了元素分析、紅外光譜、熱重和X射線單晶衍射測(cè)定.
Vario Micro cube型元素分析儀;FTIR-650型傅里葉變換紅外光譜儀(KBr壓片);SMART-APEX型X-射線單晶衍射儀;Perkin-Elmer TGA7型差熱/熱重分析儀.所有試劑均為分析純.
將Ni(OAc)2·4H2O(0.4mmol),H2NIPH(0.2mmol)和phen(0.2mmol)充分混合,用NaOH調(diào)節(jié)pH為6.14,封入25mL聚四氟乙烯襯底的高壓反應(yīng)釜中,使其在150℃自生壓力下充分反應(yīng)168h,自然冷卻至室溫,過濾,用蒸餾水洗滌,得到藍(lán)色塊狀晶體,產(chǎn)率為45%.元素分析理論值(%)(C40H23N6Ni2O13):C,52.62;H,2.54;N,9.20.元素分析實(shí)驗(yàn)值(%):C,52.59;H,2.49;N,8.99.紅外光譜:3422w,3109w,2921w,2363w,1646s,1530s,1516w,1455w,1426m,1370m,1352m,1219w,1134w,1104w,1087w,926w,906w,868w,843m,804w,787m,771w,739w,728m,710w,702w,644w,527w,452w,443w.
選取尺寸為0.661mm×0.254mm×0.220mm的晶體放置在SMART-APEX CCD上進(jìn)行X射線衍射數(shù)據(jù)收集,用石墨單色化的MoKα(λ=0.71073?)作為入射輻射,在2.64°≤θ≤27.07°范圍內(nèi),室溫(293K)下共收集獨(dú)立衍射點(diǎn)3472個(gè),其中I>2σ(I)的可觀測(cè)點(diǎn)2973個(gè).晶體結(jié)構(gòu)由直接法解出,非氫原子的坐標(biāo)是在以后的數(shù)輪差值Fourier合成中陸續(xù)確定的,對(duì)全部非氫原子的坐標(biāo)及各向異性參數(shù)用SHELXL-97[11-12]程序以最小二乘法修正,對(duì)F2進(jìn)行精修.該配合物屬于正交晶系,Pnna空間群,其晶體學(xué)數(shù)據(jù)為a=29.547(4),b=18.041(3),c=6.5860(10)?,V=3510.7(9)?3,Z=4,dc=1.727g/cm3,μ=1.157mm-1,F(xiàn)(000)=1860,R1=0.0276,wR2=0.0769.
配合物的主要鍵長(zhǎng)及鍵角列于表1.
表1 主要鍵長(zhǎng)(?)和鍵角(°)
Symmetry transformations used to generate the equivalent atoms:A:x,-y+1/2,-z+1/2
X-射線晶體學(xué)研究表明配合物具有二維網(wǎng)狀結(jié)構(gòu).其基本結(jié)構(gòu)單元如圖1所示.其不對(duì)稱結(jié)構(gòu)單元包括1個(gè)Ni(II)原子、1個(gè)5硝基間苯二甲酸分子、1個(gè)1,10-鄰啡啰啉分子和0.5個(gè)配位水分子.鎳(II)原子為六配位的分別與3個(gè)不同的5-硝基間苯二甲酸的羧基氧原子、配位水上的氧原子和1,10-鄰啡啰啉上的兩個(gè)氮原子配位(Ni(1)-O(1)=2.0476(13),Ni(1)-O(2)=2.0223(13),Ni(1)-O(3)=2.1718(14),Ni(1)-O(7)=2.0776(11),Ni(1)-N(1)=2.0658(16),Ni(1)-N(2)=2.1033(16)?),因此呈現(xiàn)畸變的八面體幾何構(gòu)型.Ni-N鍵鍵長(zhǎng)范圍為2.0476(13)~2.0658(16)?,Ni-O鍵鍵長(zhǎng)范圍為2.0223(13)~2.1718(14)?,N(O)-Ni-O(N)鍵角范圍為79.88(6)~174.48(5)°,都在正常范圍內(nèi),與其它文獻(xiàn)報(bào)道相符.
有趣的是每個(gè)5-硝基間苯二甲酸作為單齒和雙齒橋聯(lián)配體連接相鄰的兩個(gè)鎳原子,形成雙核亞建構(gòu)單元,該每對(duì)亞建構(gòu)單元又被5-硝基間苯二甲酸連接成二維網(wǎng)狀結(jié)構(gòu)的配位聚合物,如圖2所示.X-射線結(jié)構(gòu)分析,發(fā)現(xiàn)在配合物[Ni(NIPH)(phen)(H2O)0.5]2n中存在O-H…O氫鍵(O7-H7A…O4),這種分子間的弱相互作用連同共價(jià)鍵作用對(duì)構(gòu)筑配合物的2D網(wǎng)狀結(jié)構(gòu)和穩(wěn)定其構(gòu)型起到了決定性作用.
圖2 沿c軸方向的無限二維網(wǎng)狀結(jié)構(gòu)
圖3 [Ni(NIPH)(phen)(H2O)0.5]2n的熱失重曲線
配合物的TG曲線(圖3)可分為兩步連續(xù)的失重.第一步失重從15.9~318°C,失重量49.9%,可歸屬于配位水和5-硝基間苯二甲酸分子的失去,與計(jì)算值47.7%相符;第二步失重從318~433°C,失重量27.0%,對(duì)應(yīng)著phen配體的失去,同理論失重量28.9%相符.最后的剩余物為NiO.
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通化師范學(xué)院學(xué)報(bào)2013年8期