馮文浩, 喬純杰, 冉春玲, 杜 薇, 徐 琰, 樊耀亭
(鄭州大學(xué) 化學(xué)系,河南 鄭州 450052)
由于二茂鐵(FcH)衍生物可逆的單電子氧化還原性,以其為結(jié)構(gòu)單元的氧化還原型受體分子的研究非?;钴S[1,2]。二茂鐵氨基硫脲因具有可能與茂環(huán)共軛的硫脲基團(tuán),不僅具有較強(qiáng)的生物活性[3,4]和優(yōu)良的配位性能[5],還能夠作為陰離子受體識(shí)別某些陰離子[6],但其對(duì)陽(yáng)離子的識(shí)別的研究卻很少。
在結(jié)構(gòu)上,該類配體的配位方式靈活多樣,與金屬配位時(shí),通常存在多樣的配位方式,可以用來(lái)構(gòu)筑多維和各種拓?fù)浣Y(jié)構(gòu)的超分子化合物[7~10]。考慮到有延伸π電子共軛體系的金屬有機(jī)化合物在光、電、磁性等方面有的獨(dú)特性能[11~14],本文在硫脲基團(tuán)的基礎(chǔ)上進(jìn)一步增加配位原子,增強(qiáng)化合物的離域π鍵,以二茂鐵雙二氨基硫脲腙(1)和取代醛(2a~2g)為原料,經(jīng)取代反應(yīng)合成了7個(gè)新型的1,1′-二取代二茂鐵雙二氨基硫脲腙席夫堿化合物(3a~3g, Scheme 1),其結(jié)構(gòu)經(jīng)UV,1H NMR, IR和元素分析表征。研究了2對(duì)金屬離子的電化學(xué)識(shí)別性能。
CompabcdefgAr-OHS-MeO--HOHO-O-O2N-
Scheme1
北京科儀XT4A型顯微熔點(diǎn)儀;HP8453型紫外光譜儀(室溫,DMF為溶劑);Bruker DPX 400 MHz型核型共振儀(CDCl3為溶劑,TMS為內(nèi)標(biāo));Nicolet NEXUS 470 FT-IR型紅外光譜儀(KBr);美國(guó)FLASH 1112型元素分析儀;美國(guó)CHI公司650A型電化學(xué)工作站1參照文獻(xiàn)[15]方法合成,其余所用試劑均為分析,使用前未進(jìn)一步純化;所用溶劑使用前均經(jīng)干燥處理。
在三頸瓶中加入1 0.45 g(1 mmol),無(wú)水乙醇20 mL,蒸餾水60 mL及冰醋酸2 mL,攪拌溶解使其溶解;氮?dú)獗Wo(hù)下滴加2(約2 mmol)的無(wú)水乙醇(20 mL)溶液,滴畢,回流(70 ℃)反應(yīng)2 h。減壓過(guò)濾,濾餅用蒸餾水(3×10 mL)洗滌后再用熱無(wú)水乙醇(2×10 mL)洗滌,常溫干燥得3a~3g。
3a: 橙紅色固體,產(chǎn)率86%, m.p.>220 ℃; UVλmax: 307, 335 nm;1H NMRδ: 2.49(s,J=6.09 Hz, 6H, CH3), 4.46(s,J=4.07 Hz, 4H, FcH), 4.94(s,J=3.99 Hz, 4H, FcH), 6.92~7.39(m,J=8.12 Hz, 8H, ArH), 8.76(s,J=2.10 Hz, 2H, CH=N), 10.74(s,J=1.99 Hz, 2H, NH), 11.65(s,J=1.96 Hz, 2H, OH); IRν: 3 441, 3 288, 1 619, 1 520, 1 126, 1 042, 756, 479 cm-1; Anal.cacld for C30H30N8O2S2Fe: C 55.05, H 4.62, N 17.12, S 9.80; found C 54.46, H 4.06, N 16.49, S 9.42。
3b: 橙紅色固體,產(chǎn)率72%, m.p.205 ℃~206 ℃; UVλmax: 335 nm;1H NMRδ: 2.49(s,J=6.00 Hz, 6H, CH3), 4.45(s,J=4.03 Hz, 4H, FcH), 4.80(s,J=4.12 Hz, 4H, FcH), 6.92~7.39(m,J=6.06 Hz, 6H, ArH), 8.30(s,J=2.23 Hz, 2H, CH=N), 10.40(s,J=1.84 Hz, 2H, NH); IRν: 3 448, 3 315, 1 592, 1 520, 1 112, 1 041, 853, 481 cm-1; Anal.cacld for C26H26N8S4Fe: C 49.20, H 4.13, N 17.66, S 20.21; found C 50.03, H 4.02, N 17.42, S 18.46。
3c: 橙紅色固體,產(chǎn)率83%, m.p.211 ℃~212 ℃; UVλmax: 331 nm;1H NMRδ: 2.49(s,J=6.50 Hz, 6H, CH3), 3.86(s,J=6.00 Hz, 6H, OCH3), 4.32(s,J=4.00 Hz, 4H, FcH), 4.76(s,J=4.09 Hz, 4H, FcH), 6.95~7.66(m,J=8.31 Hz, 8H, ArH), 8.04(s,J=2.20 Hz, 2H, CH=N); IRν: 3 444, 2 961, 1 605, 1 114, 1 072, 1 027, 829, 481 cm-1; Anal.cacld for C32H34N8O2S2Fe: C 56.30, H 5.02, N 16.41, S 9.39; found C 55.36, H 4.80, N 15.65, S 8.72。
3d: 黃色固體,產(chǎn)率80%, m.p.180 ℃~181 ℃; UVλmax: 327 nm;1H NMRδ: 2.49(s,J=6.00 Hz, 6H, CH3), 4.33(s,J=4.13 Hz, 4H, FcH), 4.46(s,J=4.01 Hz, 4H, FcH), 6.56~7.85(m,J=10.20 Hz, 10H, ArH), 8.60(s,J=1.60 Hz, 2H, CH=N), 11.57(s,J=1.88 Hz, 2H, NH); IRν: 3 441, 3 284, 2 997, 1 601, 1 130, 1 067, 876, 505 cm-1; Anal.cacld for C30H30N8S2Fe: C 57.87, H 4.86, N 18.00, S 10.30; found C 58.88, H 4.81, N 17.76, S 10.16。
3e: 橙紅色固體,產(chǎn)率76%, m.p.240 ℃; UVλmax: 319 nm;1H NMRδ: 2.49(s,J=6.02 Hz, 6H, CH3), 4.46(s,J=4.01 Hz, 4H, FcH), 4.94(s,J=4.11 Hz, 4H, FcH), 6.92~7.28(m,J=8.05 Hz, 8H, ArH), 8.75(s,J=1.87 Hz, 2H, CH=N), 10.69(s,J=2.08 Hz, 2H, NH); IRν: 3 448, 1 626, 1 521, 1 469, 1 353, 1 306, 1 284, 1 234, 1 129, 1 039, 886, 834, 744, 575 cm-1; Anal.cacld for C30H30N8O4S2Fe: C 52.48, H 4.40, N 16.32, S 9.34; found C 52.04, H 4.73, N 15.59, S 9.10。
3f: 橙紅色固體,產(chǎn)率68%, m.p.212 ℃~213 ℃; UVλmax: 304 nm;1H NMRδ: 2.49(s,J=6.18 Hz, 6H, CH3), 4.46(s,J=4.17 Hz, 4H, FcH), 4.94(s,J=4.22 Hz, 4H, FcH), 6.93~7.39(m,J=8.31 Hz, 8H, ArH), 8.69(s,J=1.88 Hz, 2H, CH=N), 10.80(s,J=1.89 Hz, 2H, NH); IRν: 3 448, 3 125, 2 967, 1 621, 1 516, 1 471, 1 373, 1 302, 1 248, 1 135, 1 112, 1 042, 1 017, 938, 897, 851, 794, 590 cm-1; Anal.cacld for C26H26N8O2S2Fe: C 51.83, H 4.35, N 18.60, S 10.64; found C 51.13, H 4.34, N 17.80, S 10.26。
3g: 淺紫色固體,產(chǎn)率90%, m.p.215 ℃~219 ℃; UVλmax: 367 nm;1H NMRδ: 2.49(s,J=6.06 Hz, 6H, CH3), 4.46(s,J=4.14 Hz, 4H, FcH), 4.94(s,J=4.03 Hz, 4H, FcH), 6.96~7.39(m,J=7.82 Hz, 8H, ArH), 8.76(s,J=2.19 Hz, 2H, CH=N), 10.74(s,J=1.79 Hz, 2H, NH);ν: 3 442, 2 923, 1 600, 1 468, 1 357, 1 297, 1 112, 1 035, 897, 815, 675, 585, 472 cm-1; Anal.cacld for C30H28N10O4S2Fe: C 50.57, H 3.96, N 19.66, S 9.00; found C 50.98, H 4.08, N 19.82, S 8.44。
以玻碳電極為工作電極,Ag/AgCl電極為參比電極,鉑絲為輔助電極,以c(TBAP)=0.1 mol·dm-3的DMF溶液為支持電解質(zhì),在c(3)=5×10-4mol·dm-3下,在室溫和0.4 V~1.4 V電位下,對(duì)其進(jìn)行循環(huán)伏安掃描,測(cè)定3的電化學(xué)性質(zhì)。
IR分析表明,3在1 130 cm-1~1 112 cm-1, 1 067 cm-1~1 027 cm-1和514 cm-1~476 cm-1為FcH的νC-H和νFe-Cp振動(dòng)特征吸收峰;3 448 cm-1和3 284 cm-1為亞氨基的伸縮振動(dòng)峰;1 619 cm-1和1 592 cm-1為-CH=N的特征伸縮振動(dòng)峰,與其它化合物的-CH=N的相比,3的振動(dòng)峰均發(fā)生了不同程度的紅移[16]。
由3的1H NMR數(shù)據(jù)可見(jiàn),甲基質(zhì)子對(duì)應(yīng)2.49, FcH為4.32~4.94,苯環(huán)為6.56~7.85, -CH=N為8.04~8.76,均和各功能團(tuán)圖譜相符。
從3的UV數(shù)據(jù)可以看到在327 nm~335 nm有一較強(qiáng)的吸收峰,可能是FcH環(huán)與-CH=N電子共軛體系產(chǎn)生的吸收峰;在304 nm~307 nm和335 nm 兩處的吸收峰,可以歸屬于苯環(huán)和芳香亞胺的π-π*躍遷[17,18]。
3的電化學(xué)實(shí)驗(yàn)結(jié)果表明,3a~3g均在0.8 V附近出現(xiàn)了一不可逆氧化峰。在第二周掃描時(shí),峰電流明顯降低;第五周時(shí)不可逆氧化峰趨于消失,說(shuō)明在高電位的氧化還原反應(yīng)中,產(chǎn)物在電極表面形成鈍化層,阻礙了電極與反應(yīng)物的接觸。
考察了3對(duì)Ag+, Zn2+, Ni2+, Cr3+, Cu2+, Ho3+, Eu3+和Er3+(M+)的識(shí)別性能(圖1和圖2),結(jié)果表明,只有3a和3b對(duì)金屬離子有較好的電化學(xué)響應(yīng)。3a只對(duì)Ag+的明顯響應(yīng),對(duì)其余M+幾乎無(wú)響應(yīng)。此外,當(dāng)加入等物質(zhì)量的Cu2+, Ag+, Ni2+, Cd2+, Co2+, Mn2+, Hg2+, Pb2+和Ba2+時(shí),其氧化峰電位(Epa)正移程度和單獨(dú)加入Ag+時(shí)無(wú)明顯差別。
Potential/V圖1 3a, Ag+和3a+Ag+的循環(huán)伏曲線*Figure 1 Cyclic voltammetry curves of 3a, Ag+和3a+Ag+*DMF, c=5×10-4 mol·dm-3
從圖1可以看出自由Ag+的Epa為518 mV,自由配體相比之下峰值未標(biāo)出,3a+Ag+的Epa為812 mV, Ag+的Epa正移達(dá)294 mV,可見(jiàn)Ag+與3a發(fā)生了一定程度的絡(luò)合,3a可以對(duì)Ag+進(jìn)行電化學(xué)識(shí)別。
Potential/V圖2 3b和3b+Zn+的循環(huán)伏曲線*Figure 2 Cyclic voltammetry curves of 3b和3b+Zn2+*乙腈, c=5×10-4 mol·dm-3
在乙腈中,3b對(duì)Cu2+, Ni2+, Cd2+, Co2+, Mn2+, Hg2+, Pb2+和Ba2+等幾乎無(wú)響應(yīng),當(dāng)加入等物質(zhì)量的Zn2+, Cu2+, Ni2+, Cd2+, Co2+, Mn2+, Hg2+, Pb2+和Ba2+時(shí),其Epa正移程度和單獨(dú)加入Zn2+時(shí)無(wú)明顯差別。從圖2可見(jiàn),3b的Epa為826 mV,而3b+Zn2+的Epa為961 mV,3b的Epa正移達(dá)135 mV,說(shuō)明Zn2+和3b也發(fā)生了一定程度的絡(luò)合,3b可以對(duì)Zn2+進(jìn)行電化學(xué)識(shí)別。
合成了7個(gè)新型的1,1′-二取代二茂鐵雙二氨基硫脲腙席夫堿化合物。電化學(xué)研究結(jié)果表明,3a和3b對(duì)Ag+和Zn2+有較好的電化學(xué)識(shí)別能力。
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