5-氨基-1,10-菲咯啉:可异构化杂环螯合荧光载体作为比例计量型锌离子荧光探针的一种原型
2022-12-08
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维普资讯 http://www.cqvip.com 第7期 2007年7月 无 机 化 学 学 报 Vol|23 No.7 CHINESE JOURNAL OF INORGANIC CHEMISTRY Ju1.,2007 5.氨基.1,1 0.菲咯啉:可异构化杂环螯合荧光载体 作为比例计量型锌离子荧光探针的一种原型 张玉明 赵永梅 邱 琳1,2吴正轶 1 何卫江*.113 张 宇 刘德军 f1南京大学化学化工学院,配位化学研究所,配位化学国家重点实验室,南京 210093) fz江苏大学化学化工学院,镇江213013) 223300) (3淮阴师范学院化学系,江苏省低维材料重点建设实验室,淮安关键词:锌:荧光探针;异构化;比例计量测定 中图分类号:0614.24+1 文献标识码:A 文章编号:1001-4861(2007)07・1309-06 5-amino.1,10.phenanthroline:A Prototype of Tautomeric Heterocyclic Aromatic ZHANG Yu—Ming ZHAO Yong—Mei QIU Lin 0 WU Zheng—Yi HE Wei—Jiang 、 3 ZHANG Yu LIU De—Jun ( State Key Laboratory ofCoordination Chemisty,Schoolr ofChemisty rand Chemical , 艘e^, NanjingUnive ̄ity,Nanjing 210093)  ̄Schoal fChemiosty rand Chemical Engineering,jiangsu University,Zhenjia ̄g,Jiangsu 212013)  ̄Jiangsu Key Laboratoryfor Chemistry fLow—oDimensional Materils,Huanyian Teache ̄College,Huaian,J/angsu 223300) Abstract:5-amino一1,10一phenanthroline (5一AP),as a tautomeric heterocyclic aromatic chelating fluorophore hiiing emission from 495 to 564 nm upon Zn addition in ethano1.The (THACF),can sense Zn selectively by S fratiometric fluorescent sensing behavior has been correlated to the tautomerization of 5一AP affected by solvents and metal chelation.The strategy using THACF as ratiometric fluorescent sensor for Zn not only simplifies the synthetic procedure but also gives a promising alternative for Zn ratiometric fluorescent sensor design. Key words:zinc;fluorescent sensor;tautomerization;ratiometric determination As the second most abundant transition metal in temporal distribution of labile Zn are currently attract— ing much more attention due to its high sensitivity and selectivityf3】.Most of the reposed probes were construc— ted by bridging fluorophore and ionophore with a suita— the human body,zinc plays n aessentil arole in cellular metabolism,gene expression,apoptosis and neurotrans— mission ll】.Histochemical studies have discovered that herte are many pools of lbiale Zn in mammalian orga— ns。and abnormal accumulation of Zn2 has been asso— ble spacer[ ̄1,yet the fluorescent ionophores(normally are heterocyclic aromatic chelating fluorophores)with— out spacer and mere ionophore should be appreciated ciated with Alzheimer S disease.dibetes aand cancers回. he fTluorescent probes for he dettection of spatil and a收稿13期:2007-1M.23。收修改稿13期:2007-05.31。 due to the simpliifed synthetic procedure.Although the 国家自然科学基金资助项目(No.20571043)。 通讯联系人。E・mail:heweij69@nju.edu.an 第一作者:张玉明,女,26岁,硕士研究生;研究方向:生物无机化学。 维普资讯 http://www.cqvip.com 131O 无机化学学报 第23卷 intensity—based fluorescent probes are of high value in tracking and indicating Zn 。they can not provide qua— ntitative information of Zn in living systems.The more attractive Zn sensors are ratiometric fluorescent sen— are al1 non—facile compounds due to the complicated synthetic procedures141. In this paper,we propose a new strategy to design ratiometric Zn fluorescent sensor,in which tautomeric I10_∞∞_昌 sors due to their ability to quantify Zn in complicated biosystems[4].Different from the chelation enhancement heterocyclic aromatic chelating lfuorophores(THACFs) is used as the sensor.In this way,not only can Zn be quantiied ratiometrically,but also the synthetic fprocedure of the sensor can be simplified.1。1 0一 phenanthroline and its derivatives are widely used not only as metal chelating agents but also as fluorescent sensors when combined with other coordinating motifs, and most of them are Zn sensorst I.However.al1 of them are intensity—based sensors.Here。5一amino一1。1 0一phena— of the lfuorescence(CHEF)imposed by intensity—based sensor,the ratiometric fluorescent sensors make use of Zn chelation shitf of the lfuorescence(Zn—CHSF1 t0 sense Zn“.Besides the changed molecular dipole mo— ment。fluorophore tautomerization induced by Zn che一 1ation also 1cad to emission shit.In thifs case.the different Zn binding ability of different tautomer resu一 1ts in the ratio of dual emission change upon Zn addit— ion.Determination of the varied ratio finally gives the nthroline(5一AP),a typical THACF,is reported as ratio— metic sensor for Zn ,due to its tautomerization fSche— I10Is∞_昌 quantifying ifornmation of Zn (Scheme l a).However, the current reported ratiometric Zn2 ̄-fluorescent sensors me l b)affected by Zn chelation. Zn(11) V l‘ Wavelength Wavelength (a)ratiometric Zn“determination of tautomeric fluorescent sensor NH Tautomer 1 Tautomer 2 (b)tautomerization of 5-amlno一1,10一phenanthroline Scheme 1 1 Experimental Ethanol,methanol,/so—propanol,chloroform,dich— loromethane,DMSO are of spectrospic grade from TEDIA.All metal sahs are of analytical gradeOther .H NMR spectrum was determined by Brucker DRX一 500.All the UV—Vis spectra were recorded by Shimadzu UV一3 1 00 spectrophotometer and the emission spectra were obtained using an AMINCO Bowman Series 2 fluorescence spectrophotometer. reagents for synthesis are all commercially available. 维普资讯 http://www.cqvip.com 第7期 张玉明等:5.氨基.1,10.菲咯啉:可异构化杂环螯合荧光载体 作为比例计量型锌离子荧光探针的一种原型 l3ll 1.1 Synthesis 0f 5-AP 1 g 0f 5一nitro.1,10一phenanthroline(4.44 mmo1) was dissolved in 60 mL ethano1.To the stirring solution, freshly prepared Raney Ni and aqueous NH2-NH2。H20 f70%1 were added in portions at 70℃until no raw mat— erials could be detected by TLC.Filter off the solid and the ifltrate was de—colorized by silica gel column(5 cm) with ethanol as the eluent.Remove most of the ethanol in vacuo and precipitate in pale yellow solid was formed.Then 347 mg product was obtained via ifltration.Yield.40%.MP.256~258 oC.‘H NMR(500 MHz,CDC13,6,ppm):6.10 br,2H),6.98(S,1H),7.51 (q,1H),7.63(q,1H),8.00(m,1H),8.30(q,1H),8.96(q, 1H),9.22(t,1H)昀.Elementla analysis for Cl2H9N3: Calcd.:C,73.83;H,4.65,N,21.52%.Found:C,73.55; H,4.90;N,21.78%. 1.2 Emission spectra determination Emission spectra in dichloromethane,chloroform, iso—propanol,ethanol,methanol and 5%aqueous DMSO were determined at the concentration of 1×10-5 mol・L~. Metal cation titration experiments and competition experiments were completed in ethano1. I1he concentra— tion of 5一AP was 3 xl0 mol・L-i.The tested metal cations were Mn ,C0 ,Fe ,FeⅢ,Ni ,Cu ,Mg ,Zn , Cdn.Can and the concentrati0n was 4.5xl0-3 mo1. ‘in ethano1.3 mL 5.AP solution in cuvette was added with laiquots of metla cation solution(3 L). I1he spectra were obtained after each addition under the irradiation at 354 nm.Competition experiments were also finished in cuvette.100 equivalents of K and Na (6 L),0.5 equivalent of Mg r6 IxL)and 0.5 equivalent of zn2 were added in sequence and the emission spectrum was recorded after each addition. 2.1 Emission behavior of 5.AP in different solvents Due to the solvent effect in the tautomerization of THACFs,they can not always act as ratiometric lfuorescent sensor.If only the Zn +-prefering tautomer can exist in the solvent.there will be no distinct Zn2+- triggered emission shitf,which is demanded for ratiometric Zn2 determination.Therefore,the emission behavior of 5一AP in diffe:ernt solvents were studied for the purpose to ifnd suitable solvent for ratiometric Zn determination.Moreover,the study should be helpful to understand the emission behavior of 5一AP.From Fig.1, one can ifnd that the solvent polarity is quite essentila to the emission intensity of 5一AP and higher solvent polarity leads to lower emission intensity.The emission intensity in ethanol and methanol is no more than 1/10 of those found in other tested solvents(dichloro— methane,chloroform and/so—propano1).Moreover,the emission intensity in/so—propanol is still lower than those found in dichloromethane and chloroform probably due to its higher polarity.On the other hand, only in/so—propanol and ethano1.5一AP displays dual emission,495 nad 522 nm in ethanol(A =354 nm),494 nad 5 19 nm in/so—propanol(A =354 nm).Solvents of even lower polarity make the emission blue—shitfed to -454 Bin and only one emission band can be observed (dichloromethane and chloroform).Solvents of even higher polarity(methano1)lead to an obvious batho— chromic shitf to-569 nm and only one emission band is observed.It seems that solvents of higher polarity favor one tautomer of 5一AP(tautomer 1),which emits at longer wavelength,while the solvents of lower polarity favor another tautomer(tautomer 2),which emits at shorter wavelength.For the solvents of medial polarity, the co—existence of tautomers leads to the dual emission.As to the lower emission intensity in solvents of hihger polarity,it is a normal case for fluorophore due to the polarized environment favor the excited molecules transferring energy to other molecules in a nonradiation pathwav网. Wavelength/nnl Fig.1 Emission behavior of 5-amino-1,10-phenanthroline in diferent solvents 维普资讯 http://www.cqvip.com 1312 无机化学学报 第23卷 The emission behavior of 5一AP in water was ion band can be found in the final emission spectrum. The different response of the two emissions upon Zn chelation makes it a otpentil acandidate as a ratiometric 一.j.曼^llsg若 3Ⅱo。s l0:= studied in 5%DMSO aqueous solution due to its insolubility in water.It was found that 5一AP was almost non—emissive at diferent pH values.The intensive intermolecular interaction between water and 5一AP molecules should be responsible for it. 2.2 Fluorescentresponseof5-APtoZn Because metl saalts are dififcult to be dissolved in solvents of lower polarity,ethanol,methanol and sensor for Zn .On the other hand,the titration profile indicates that only one Zn2 complex is formed and the binding ratio is 3:1(5一AP/zn2+,Fig.2a inset).The initila I |I is around 0.6,and the enhancement factor of I姒 /,蛳caused by 0.5 equivalent of Zn is around 21(Fig. 2b1. DMSO—containing water(5%)are the suitable solvents or fZn2+detection. In ethanol,5一AP should be suitblae or fratiometric detection of Zn2+because of its dual emission in ethano1. From Fig.2.one can ind tfhat the emission of 5一AP in ethanol is shitfed bathochromically from 495 to 564 nm Although 5一AP in DMSO—containing water(5%) lmosta becomes non—emissive.Zn2 titration still induc— es a new emission at~560 nm.However,the very low emission intensity implies that it is of nonsense for Zn detection.Zn2 titration in ethanol and water lla demon— strates that 5一AP—Zn2 complex emits at~560 nm. : n。 = l1 which is quite close to the only emission of 5.AP upon Zn¨addition,just as expected.Moreover,the gradually enhanced emission at 564 nm and the raduaglly decreased emission at 495 am induced an (tautomer 2.570 nm1 in methano1.Since it is dificult to diferentiate exactly the two emissions,5一AP can no longer act as ratiometric sensor or fZn2 ̄in methano1. isobathic point at 5 19 am(Fig.2a)and only one emiss— 3 \ Wavelength/nln CZn2+/ ̄75 Fig.2(a)Emission spectra of 5-amino・1,10-phenanthroline upon Zn titration in ethanol and the corresponding tirattion profile according to the emission intensity at 564 am (a,inset)A ̄=354 nm;(b)corresponding titration profile referring to k, 2.3 Fluorescent selectivity of 5-AP in ethanol he fTluorescent response of 5一AP to other metl acations has lso abeen tested.Evident bathochromic shitf from 522 to 544 nm was observed when 5一AP ethanolic though of as a shoulder peak of emission at 544 nm. Evident emission quenching effect was found when ifrst row transition metal cations,MnⅡ,CoⅡFenFemNiⅡ ,,,or Cu ,were added(Fig.3b).Addition of Na and K does not lead to evident change in its emission spectra. Introduction of C82 only leads to the minor enhance— ment in emission intensity without evident emission shift.The fluorescent recognition of 5一AP for metl acations in ethanol even can be observed by naked eyes under irradiation at 365 nm.The color of 5一AP shitfs rfom gray blue to pale brown upon Zn addition,while the intreduction of M or Cu2 leads to the yellow solution was titrated by Mg (Fig.3a),with evident increase in the emission intensity.The titration profile demonstrates that the emission enhancement at 544 nm becomes no longer evident until one equivalent of Mg is added.suggesting that the binding ratio of 5一AP to M be around 1(inset of Fig.3a).There is no evident shift for he emitssion at 495 nm.except for the 2 times increment in intensity.In fact.this emission can be 维普资讯 http://www.cqvip.com 维普资讯 http://www.cqvip.com 1314 无机化学学报 第23卷 designed in THACFs,oxygen atoms(affinitive to hard metal cations)and sulfur atoms(affinitive to heavy metal cations1 should be avoided for Zn selectivity. Zn ratiometrically.The tautomerization of 5一AP。esse— ntial for its ratiometirc sensing behavior,is severely affected by the solvents and metal chelation.Moreover, the chelating heterocyclic atoms of THACF are esse— ntial for their Zn selectivity. H2N 【1】(a)BergJ M,Shi Y.Science,1996,271:1081 ̄1085 Scheme 2 Proposed Zn2 ̄-binding form of 5-AP (b)0 Halloran T V.Science,1993,261:715 ̄724 (c)Truong-Tran A 0,Carter J,Rufin R E,etf a1.Biometals, 2oo1.14:315 ̄330 The above results indicate that 5.AP as a THACF can fulfil the ratiometric fluorescent detection of Zn2+in ethano1.However.it is not a qualified ratiometric Zn2 senor in water,which is requested by most of the environmental and biological systems.A11 these should be correlated to its molecular structure.The above 【2](a)Weiss J H,Sensi S L'Koh J K.Trends Pharrnaco1.Sci., 20o0.21:395~4O1 (b)Ueno S,Tsukamoto M,Hirano T'et a1.上Cel1.BioL,2OO2, 58:215~220 (c)Cuajungco M P,Lees G J.Neumbio1.Dis.,1997,4-137 ̄169 【3】(a)Burdette A C,Lippard S J.Proc.NatL Acad.Sci.USA, 2oo3.1Oo:3605~3610 results suggest that Zn2 prefer to bind tautomer 1 over tautomer 2,displaying emission dose to that of apo tautomer 1.Therefore,only when tautomer 2,favored by intra-molecular proton transfer can be stabilized in (b)Lim N C,Freake H C,Briickner C.Chem.Eur.上'2Oo5,11: 38~49 (c ̄iang P J,Guo Z J.Coord.Chem.Rev.,2004,248(1 ̄2):205 ̄ 229 solution,then will the ratiometric sensor requested Zn.CHSF from tautomer 2 to Zn2+-chelated tautomer 1 occur.For 5-AP in ethanol,its pK is suitable to stabilize tautomer 2,while in methanol and water,their pK disfavor the tautomerization to tautomer 2. 【4](a)ChangC J,JaworskiJ,NolanEM eta1.Proc.Nat1.Acad. Sci. sA,2Oo4,101:1 129 ̄1 134  ̄)Lim N C,Briickner C.Chem.Commun..2OO4:1094~1095 【5】(a)Sammes P G,Yahioglu G.Chem.Soc.Rev.,1994:327~335 (b)Pina F,Bemardo M A,Gacia-Espana E.Eur.上Inorg. Chem..20o0:2143~2157 (c)Bencini A,Bemardo A M,Bianchi A,et a1.Ear.上Inorg. THACF com pound 5一AP.as a new prototype of ratiometric fluorescent sensor,can selectively sense Zn by determine the varied ratio of two emissions at Chem..1999:191 1~1918 (d)Bazzicalupi C,Bencini A,Bianchi A,et a1.Inorg.Chem., 1999,38:3806~3813 564 and 495 nm trigered by Zn“in ethano1.Besides simplifying the synthetic procedure,the strategy using THACF 88 fluorescent sensor or Zn can even quantiffy 【6]Lecomte J P,Mesmaeker A K,Demeunynck M,et a1.上Chem. Soc.FaradayTrans.,1993'89(17):3261~3269 [7]Vazquez M E,Blanco J B,Imperiali B.上A m.Chem.Soc., 2oo5.127:1300~1306