馮 超， 葛成敏， 王寅光， 張淑華

(桂林理工大學(xué) 化學(xué)與生物工程學(xué)院，廣西 桂林 541004)

過(guò)渡金屬聚合物具有明確有序的一維或者多維微觀結(jié)構(gòu)以及獨(dú)特的宏觀特性，選取適當(dāng)?shù)倪^(guò)渡金屬離子、配體以及合成方法可調(diào)控配位聚合物的結(jié)構(gòu)，進(jìn)而調(diào)控其性質(zhì)[1～10]。配位聚合物由于結(jié)構(gòu)的多樣性和在催化、化學(xué)吸附、磁性和電子導(dǎo)體等方面的功能特性, 近年來(lái)已受到研究人員的廣泛關(guān)注[11]。在配位聚合物的合成研究中,配體是影響結(jié)構(gòu)特征的決定性因素之一。配體的給體基團(tuán)性質(zhì)、配體的齒數(shù)、配體點(diǎn)間的間距、配體間的連接基團(tuán)以及配體異構(gòu)等諸多因素都可能對(duì)配位聚合物的最終結(jié)構(gòu)產(chǎn)生影響[12]。但是在設(shè)計(jì)和合成金屬有機(jī)骨架時(shí),控制維度仍然是一個(gè)重大挑戰(zhàn)。除了溶劑、溫度、金屬與配體的配比、模板和平衡電荷的離子外,最終的結(jié)構(gòu)還會(huì)受到如氫鍵和π-π相互作用[13]等因素的微妙影響。盡管配體的空間結(jié)構(gòu)對(duì)配合物領(lǐng)域和催化活性金屬中心有巨大的影響力,但其影響力在超分子結(jié)構(gòu)方面還沒(méi)有得到充分的重視[14,15]。在4,4′-聯(lián)吡啶(4,4′-bipy)為有機(jī)配體的合成體系中,加入客體小分子的研究較多[16,17]，但單獨(dú)以4,4′-bipy構(gòu)筑的配位聚合物的研究報(bào)道較少[18～21]。

本文以4,4′-bipy和CuCl2·2H2O為原料，在DMF中用溶劑熱法合成了新型一維配位聚合物——[Cu(4,4′-bipy)Cl]n(1)，其結(jié)構(gòu)經(jīng)IR，元素分析和X-射線單晶衍射表征。

1 實(shí)驗(yàn)部分

1．1 儀器與試劑

Bruker Vector 22 FT-IR型紅外光譜儀(KBr壓片)；Perkin-Elmer 240C型元素分析儀;Bruker SMART CCD型X-射線單晶衍射儀。所用試劑均為分析純，使用前未作進(jìn)一步純化處理。

1. 2 1的合成

在聚四氟乙烯內(nèi)襯不銹鋼反應(yīng)釜(15 mL)中加入CuCl2·2H2O 17 mg(0.1 mmol), 4,4′-bipy 15.6 mg(0.1 mmol)和DMF 10 mL,攪拌下滴加三乙胺，調(diào)至pH 8左右。置入烘箱，于120 ℃反應(yīng)120 h。自然冷卻至室溫，過(guò)濾，濾餅自然晾干得紫紅色晶體1，產(chǎn)率51%(基于Cu)； IRν: 3 459, 3 044, 1 560, 1 528, 1 478, 1 410, 1 214, 797, 723, 629, 474 cm-1; Anal.calcd for 1： C 40.07, H 3.16, N 10.97； found C 40.03， H 3.22， N 10.89。

1.3 晶體結(jié)構(gòu)測(cè)定

2 結(jié)果與討論

1的分子結(jié)構(gòu)見(jiàn)圖1，主要鍵長(zhǎng)和鍵角見(jiàn)表1。由圖1可見(jiàn)，在1的結(jié)構(gòu)單元中包括兩個(gè)Cu+，四個(gè)4,4′-bipy分子，兩個(gè)Cl-。 Cu+具有四面體的配位幾何構(gòu)型，與其配位的4個(gè)原子分別是兩個(gè)4,4′-bipy分子中的兩個(gè)N原子,兩個(gè)Cl原子。Cu-N鍵長(zhǎng)從0.198 3(2) nm～0.199 1(2) nm； Cu-Cl鍵長(zhǎng)為0.241 46 (9) nm，相應(yīng)的鍵角(N2-Cu1-Cl1，N1-Cu1-N2， N1-Cu1-Cl1和N1-Cu1-Cl1i)分別為99.4°, 126.5°， 111.2°和108.30(8)°。其中兩個(gè)Cl-起到橋聯(lián)作用連接兩個(gè)Cu+， Cu1-Cu1i鍵長(zhǎng)[0.274 7(1) nm]介于羧酸的雙核銅(0.259 nm～0.275 nm)的銅銅距離之間[24]。說(shuō)明兩個(gè)Cu+間有相互作用。為更好的精密堆積，在4,4′-bipy分子中，兩個(gè)吡啶環(huán)間的二面角是22.06°。

圖 1 1的分子結(jié)構(gòu)圖Figure 1 Molecular structure of 1

BondLength/nmBondAngle/(°)BondAngle/(°)Cu1-N10.198 30(2)N1-Cu1-Cl1111.20(8)N2-Cu1-Cl199.44(8)Cl1-Cu1i0.241 46(9)N1-Cu1-Cl1i108.30(8)Cl1i-Cu1-Cl1104.86(3)Cu1-N20.199 10(2)Cl1-Cu1-Cu1i54.94(2)N2-Cu1-Cu1i132.14(7)Cu1-Cu1i0.274 70(8)N1-Cu1-N2126.49(10)Cl1i-Cu1-Cu1i56.42(2)Cu1-Cl1i0.241 46(9)N1-Cu1-Cu1i101.29(7)Cu1i-Cl1-Cu168.63(3)Cu┈Cu0.274 70(1)N2-Cu1-Cl1i104.49(8)

i-x, -y+3/2, z

由圖2(1的2-D層狀結(jié)構(gòu)圖)可見(jiàn)，在a+c軸方向，兩個(gè)Cu+和兩個(gè)4,4′-bipy分子經(jīng)橋連作用形成一個(gè)大的20元環(huán)，并且延伸形成二維層狀網(wǎng)格，層與層之間互相平行(圖3)。這些由非常規(guī)的C-H┈Cl氫鍵(C7┈Cl1=0.093 00 nm， C7-H17┈Cl1夾角為151.70°)構(gòu)筑的二維層與另一方向的二維層形成互穿插結(jié)構(gòu)而形成三維網(wǎng)狀結(jié)構(gòu)。運(yùn)用OLEX[25]軟件，如果氯橋簡(jiǎn)化為藍(lán)線，4,4′-bipy簡(jiǎn)化為紅線，四配位的Cu簡(jiǎn)化為一個(gè)棕色點(diǎn)，則二維層可簡(jiǎn)化為一個(gè)4.82的拓?fù)?圖4)。

圖 2 1沿b軸方向的2-D層狀網(wǎng)格圖Figure 2 2-D network structure of 1 along b axis

圖 3 1沿c軸方向的堆積圖Figure 3 Packing diagram of 1 along c axis

圖 4 1的拓?fù)浣Y(jié)構(gòu)圖Figure 4 Topology structure of 1

3 結(jié)論

應(yīng)用溶劑熱法合成了新型的一維配位聚合物[Cu(4,4′-bipy)Cl]n，單晶X-射線研究表明，聚合物二維4．82的拓?fù)渫ㄟ^(guò)互相穿插形成三維空間結(jié)構(gòu)。雖然形成了20元大環(huán)結(jié)構(gòu)，但由于互相穿插自填補(bǔ)而使整個(gè)化合物并沒(méi)有空洞存在。

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