新型Zn2+基金屬有機框架結構的溫度依賴的導電、發光性能及理論計算

高義粉 莊桂林 柏家奇 鐘 興 王建國

(浙江工業大學化學工程學院，杭州310032)

新型Zn2+基金屬有機框架結構的溫度依賴的導電、發光性能及理論計算

高義粉 莊桂林*柏家奇 鐘 興 王建國*

(浙江工業大學化學工程學院，杭州310032)

通過Zn2+和1,3,5-三苯甲酸(H3BTB)配體反應獲得一種新型的四重互穿的金屬有機框架結構(MOF)1。單晶體結構分析表明這是一種由中性N,N-二甲基甲酰胺(DMF)分子和H2NMe2+陽離子沿b軸密封于通道的三維(10,3)網狀陰離子框架結構。交流阻抗測試顯示該結構的導電性能具有特殊溫度依賴性。其電導值在20oC下為0.36×10－6S·cm－1，隨著溫度升高導電能力迅速增大，160°C達到最大值2.24×10－5S·cm－1，繼續升高溫度，導電能力開始下降。分子動力學(MD)模擬和介電性質測量表明，這種特殊溫度依賴的導電性能是來自于隨溫度升高H2NMe2+陽離子遷移增強以及DMF揮發的協同效應。0.20 V的傳輸能壘接近于質子導電性能。研究表明：MOFs孔對H2NMe2+的限制作用是獲得電子材料的一種潛在理想方法。同時，在1中發現一種有趣的熒光現象，發射峰位置比在H3BTB配體中更加藍移。密度泛函理論(DFT)計算揭示這是由于在1中，配體BTB3－的離域π鍵結構破壞，禁帶寬度增大所致。

MOFs；密度泛函理論計算；導電性；冷發光

Key Words:MOFs;Density functional theory calculation;Conductivity;Luminescence

1 Introduction

Metal-organic frameworks(MOFs)1have been currently attracting enormous attentions owing to regular porous structure and potential applications,such as adsorption2,separation3,catalysis4, luminescence4c,5,magnetism6and etc.Generally,these special properties can be derived from not only the electronic structure of metal ions or ligand,but also the nanosize porous characteristic and encapsulated guest molecules or ions.Within this context, confined species often endow the material unique physical properties.Recently,it was found that these porous solids also exhibit good proton conductivity through confining small molecules or ions into the channel7,where the species serve as the role of charge carrier.These studies provide some help to understand the transport mechanism of charge carriers.However,they usually involve the conducting property of single component in the channel.And the transporting mechanisms with respect to the multi-components coexisting(e.g.neutral molecules and charged ions)conductivity are unclear.

Moreover,electronic structural changes of ligands also affect the physical properties of MOFs,e.g.luminescence.The fluorescent MOFs with tuneable electronic transition energy will be promising candidates of inorganic-organic hybrid organic light emitting diode(OLED)materials8.Their emission properties are mainly derived from metal ions,organic linker and charge transfer between them9.The conformation change of rigid ligands usually induce the transformation of electronic structure and results in the displacement of emission peaks or quantum yield9d.From the experimental view,previous studies only give some reasonable explanations on distinct phenomenon.Combined with the experiment and theory usually produces profound comprehensions on theoretical mechanisms.However,as far as our knowledge, corresponding studies are very rare.

In this study,one new Zn(II)-based MOF,which indicates threedimensional(10,3)net and confines dimethyl formamide(DMF) and H2NMe2+cation into the channel,was synthesized and characterized.Especially,it is found that the MOFs show temperaturedependent conductivity and blue-shift luminescence.The mechanisms of ionic conductivity and luminescence were further investigated by means of combination of density functional theory (DFT)and molecular dynamics(MD)calculations.

2 Experimental and computational section

DMF(99.0%),adenine(98%)were purchased from Aladdin, Zn(CH3COO)2·4H2O(98%)were obtained from Alfa Aescar, H3BTB ligand were acquired from Aladdin.All solvents were commercially available and used without further purification.

2.1 Synthesis of[Zn(BTB)(DMF)](H2NMe2)(DMF)(1)

0.219 g(0.50 mmol)benzene-1,3,5-tribenzoate(H3BTB)ligand, 0.280 g(0.75 mmol)Zn(CH3COO)24H2O and 0.117 g(0.50 mmol)adenine were dissolved into the mixed solvent of DMFH2O(1:1,volume ratio).The mixture was subsequently transferred and sealed in 25 mL Teflon-lined stainless steel container. The container was heated to 120°C at the rate of 30°C·h－1and hold at that temperature for 2880 min，and then cooled to room temperature at the rate of 3°C·h－1.Colorness block crystals of 1 were obtained in yield of 45.6%(based on H3BTB ligand).Anal. calcd(found)(%)for C35H37N3O8Zn(1):C,60.65(60.32);H,5.38 (6.01);N,6.06(5.89).IR spectra for 1(KBr),v/cm－1:476.6(w), 668.4(w),707.2(w),780.6(m),858.0(w),1017.2(w),1106.4(w), 1152.7(w),1385.9(s),1550.2(w),1605.5(s),1656.7(m).

2.2 Measurement details

H3BTB ligand was of commercial origin without further purification.The C,H,and N element analyses were performed by use of a CE instruments EA1110 elemental analyzer.The infrared spectra was measured on a Nicolet AVATAR FT-IR360 Spectrophotometer with pressed KBr pellets.The X-ray powder diffractometry(XRPD)study was performed on Panalytical X-Pert pro diffractometer with Cu-Kαradiation.Thermogravimetric analyzer(TGA)curve was recorded on a SDT Q600 instrument.UVVis diffuse-reflection adsorption was recorded on Cary 5000 Ultraviolet Visible-Near Infrared(UV-Vis-NIR)spectrophotometer,where the powder sample was put into cone-shape container.Fluorescent spectra were recorded by F7000 fluorescence spectrophotometer,respectively.Both alternating current (ac)impedance and dielectric properties measurements were performed by use of 2-wire mode on the WAYNE KERR 6500 High Frequency LCR Meter.The powdered sample was compressed to pellet with the size of 5.09 mm2×1.26 mm.Two test lines were fixed on the tabletting via electric glue and connected with the apparatus.The temperature-controlled apparatus is Sigma/ Delta instrument.Single crystals having suitable dimensions for compound 1 was used for data collection using a CrysAlis CCD diffractometer(Xcalibur,Eos,Gemini ultra)at 298 K equipped with enhance(Mo)X-ray source(λ=0.071073 nm).Integration and cell refinement were carried out using CrysAlis RED.The absorption correction was performed by multiscan method using SCALE3 ABSPACK scaling algorithm.All corrections were made for Lorentz and polarization effects.The molecular structures were solved by direct methods(SHELXL-86/SHELXL-97)and refined by full-matrix least-squares on F2(SHELXS-97).Crystal data of compound 1 are given in Table S1(Supporting Information).

2.3 Computational details

Geometrical optimization and electronic structure were performed by using of density functional theory in the DMol3module of Material Studio software10.Exchange-correlation(XC)effects between electrons and ions were treated by the generalized gradient approximation(GGA)11with Perdew Burke Ernzerhof (PBE)12formalism.The double numerical basis set plus polarization functional(DNP)12,which has a computational precision being comparable to the split-valence basis set 6-31g**,was applied in the expanded electronic wave function.For Zn element, the inner core was treated by the approach of effective core po-tential(ECP)13and 3d electrons were explicitly seen as valence electrons.For other elements,all electrons were treated in the same manner as valence electrons.For 1,the Brillouin zone integration adopted K-points of 1×2×1,which is enough to describe the whole zone.For all the calculations,the optimization convergence in energy and force were set to be 1.0×10－5Ha and 2.0×10－2Ha·nm－1,and the SCF convergence was set to be 1.0×10－6.Based on previous optimized structure,We further conducted partial density of states(PDOS)calculation,where 20 empty bands and 1×1×1 K-ponts were adopted.Molecular dynamic calculation was carried out at specific temperature of 433 K in the NVT ensemble by using of GULP14module in Material Studio software.The simulation time is 200 ps at atime step of 1 fs.An universal force field of UFF4MOF15was applied to describe interaction between atoms or functional groups.

Fig.1 Coordination environment of Zn(II)in 1(a),three-dimensional structure(b)and topology sketch(c)of 1

Fig.2 (a－c)Nyquist plots of the ac impedance of 1 over the temperature range of 20－200°C at the interval of 20°C; (d)plot of obtained conductance σ vs T

3 Results and discussion

Compound 1,[Zn(BTB)(DMF)](H2NMe2)(DMF),crystalizes in the space group of P2(1)/n of monoclinic system.Crystal structure measure reveals that the asymmetric unit contains one Zn2+ion,one BTB3－ligand,two DMF molecules and one H2NMe2+cation.As shown in Fig.1(a),the coordination geometry of Zn2+can be well described as an octahedron,featuring the contributions by six oxygen atoms.These coordinating atoms are derived from five carboxylate oxygen atoms of three BTB3－ligands and one oxygen atom of DMF molecule,respectively.The resulting Zn―O bond length is 0.1946(3)－0.2032(3)nm,which is in good agreement with those reported previously16.Via three BTB3－ligand,each Zn(II)ion links with adjacent ones and generates threedimensional(10,3)-net framework.Herein,each Zn(II)ion acts as one node,where each BTB3－ligand serves as three-connecting bridge.Four fold interpenetrations among these(10,3)-net layers along b axis are found in three stacked structure(see Fig.S2, Supporting Information),resulting in one-dimensional channels in the direction of b axis.Neutral DMF molecules and cationic H2NMe2+are sealed in this channel,as shown in Fig.1(b).The whole framework of 1 is anionic framework,as seen in Fig.1(c). Also,H2NMe2+cations are derived from the dissociation of partial DMF molecules.

Fig.3 Thermogravimetric(TG)curve(a)andArrhenius plot of the conductivity of 1(b)

As an organic alkali,adenine plays an important role in the reaction of 1.Without adenine,1 had never been obtained in same synthetic conditions.If instead of adenine by other N-containing moieties(such as 4,4-bipyridyl),it is found that the resultant white product was not pure by the identification of PXRD.Herein,it must be mentioned that the topology of 1 is similar with Cd(II)-based MOFs reported by Kitagawa et al.16.However,the larger difference between them is that in this Cd(II)-based counterpart, H3BTB ligand only lost two protons and thereby led to the absence of H2NMe2+cation.

Fig.4 (a)Fluorescence spectra of 1 and H3BTB ligand; (b)band structure and partial and total DOS of 1

In order to study the electrical property of 1,alternating current impedance measurements with the frequency from 20 Hz to 10 MHz were performed by use of the powder tablet of single crystals.Fig.2 displays Nyquist plots of 1 at different temperatures.At low frequency,Nyquist plots feature semicircle shape.It is interestingly found that the radius firstly becomes smaller until 160°C and then rapidly reduces.Further,it can be simply fitted by the equation of RC equivalent circuit,as shown in Fig.2(a－c). The obtained conductance at 20°C is 0.36×10－6S·cm－1.With an increase of the temperature,the conductance value increases and reaches the maximum of 2.24×10－5S·cm－1at 160°C.Subsequently,the conductance value sharply reduces until the value of 1.14×10－5S·cm－1at 200°C,as displayed in Fig.2(d).

What is charge carrier in 1?In the channel,there are two different species,DMF molecule and H2NMe2+cation.Thermogravimetric analysis result shows that the guest DMF molecules are completely removed at about 160°C with weight loss of 9.5%(theoretically calcd 10.5%),and the coordinated DMF molecules fully lose at 400°C(see Fig.3(a)).As shown in Figs.S2－S3 (Supporting Information),a powder X-ray diffraction at different temperature indicates that the while structure may partially decompose at 160°C.It is mentioned that the difference of peak intensity at different temperature may be resulted from the thermal swell of sample under the test.However,the main framework is still stable,being confirmed by the result of MD simulation,as shown in Fig.S5(a)(Supporting Information).Normally,neutral DMF molecules have no capacity of acting as carrier of ionic current.It is therefore that the decrease of guest DMF molecules has never apparently affected the conducted property.Instead, H2NMe2+cations play an important role.As the increase of temperature,the crystal-boundary resistance of powder sample improves,while the mobility of H2NMe2+cations is also enhanced and thereby reduces the inner resistance of polycrystals.Obviously,the latter effects can effectively counteract the crystal-boundary effects.After 160°C,the decrease of conductance value can be attributed to the fact that structural collapsing of 1 leads to the deficiency of ionic channel.Moreover,Fig.3(b)shows the curve of conductivities,σ(log scale),as functions of 1000/T.Arrhenius plots[lnσ vs 1000/T]exhibited a linear relationship with an activation energy(Ea)of 0.20 eV over the temperature range 20－160°C.This value of Eais in good agreement with those of the reported proton conductive system13.Thus,it is observed that the confinement of H2NMe2+in the pores of MOFs may be one promising synthetic method of electrical material.

Furthermore,dielectric properties under different temperatures were conducted,as shown in Fig.S5(b)(Supporting Information). As the temperature increase,dielectric constant firstly rises before 80°C,suggesting that some DMF molecules may be polarized so as to improve the amount of carrier.Subsequently,it fell into decline until about 140°C,which may be attributed to the removal of DMF molecule and an increase of disorder of H2NMe2+with the increase of temperature.Nonetheless,dielectric loss firstly decreases before 80°C and then increases until the maximum at 140°C.The critical temperature of 140°C may be less than that of conductivity,owing to synthetic effect of the removal of guest DMF molecules and the increase of disorder of H2NMe2+cations. With the frequency increasing,the dielectric constant decreases, while dielectric loss rises.It was observed that the magnitude of the dielectric constant at the temperatures higher than 80°C at f= 1 kHz was at least two times larger than that at 140°C,suggesting a slow ionic motion rather than fast electronic motion11.Therefore, the origin of electrical property in 1 is derived from transfer of H2NMe2+cation.

Fig.5HOMO－2(a),HOMO－1(b),HOMO(c),LUMO(d),LUMO+1(e)and LUMO+2(f)of 1

Fluorescent spectra of 1 and H3BTB ligand were measured in solid state at room temperature.As shown in Fig.4(a),two emission peaks of 361 nm for 1 and 396 nm for H3BTB ligand were found,respectively.Interestingly,the wavelength of emission peak in 1 is less than that of H3BTB.In order to explain the mechanism,DFT calculations were performed.Geometric optimization of 1 was divided into two steps:non-hydrogen atoms restricted optimization was firstly carried out,and subsequentlythe obtained structure was further fully relaxed.The final optimized geometry was in good agreement with that derived from single crystal diffraction.Band structure and local density of states were also examined,as shown in Fig.4(b).Band curves in the vicinity of Fermi level are not well dispersed across different region,hinting that the conjugated degree of H3BTB ligand is destroyed after the formation of MOFs.The band gap of 3.3 eV coincides well with the solid UV adsorption peak of 398 nm(see Fig.S6,Supporting Information).Inspecting the PDOS of 1,we can find that the contribution of conduction band are mainly attributed to 2p state of C atoms in the BTB3－ligand.And the tiny role is played by the 3d state of Zn(II)ions.The first empty bands at the position of 3.3 eV are completely resulted from the 2p state of C atoms in the BTB3－ligand.Thus,the observed emission peak can be essentially attributed to the mixed transition of LLCT and MLCT.For the case of H3BTB ligand,geometric optimization was performed,and the obtained configuration was further confirmed by frequency analysis.Scrutinizing the finial structure shows that four phenyl group lie on the same plane,leading to stronger rigidity.The 3.02 eV between the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital (LUMO)of 3.02 eV(ca 409 nm)is in good agreement with the emission wavelength of 396 nm.

Moreover,frontier orbitals of 1 at Gamma point and H3BTB ligand were identified,as shown in Fig.5 and Fig.6.HOMO and HOMO－1 are degenerative orbitals.LUMO and LUMO+1 are also degenerative orbitals.HOMO,HOMO－1 and HOMO－2 are contributed mainly by p-type dangling orbits of carboxylate oxygen atoms in BTB3－ligand and 3d orbits of Zn(II)ions,while LUMO,LUMO+1 and LUMO+2 mainly arise from p-type dangling orbits of carboxylate oxygen atoms in BTB3－ligand.For the case of H3BTB ligand,HOMO is delocalized π-type bonding orbital,while LUMO is localized π-type anti-bonding orbital.In comparison with frontier orbitals of H3BTB ligand,it is observed that the coordination of Zn(II)ion makes the delocalized π-type bonds of 1 destroyed so as to increase the band gap.That is the reason why the position of emission peak occurs to more blue shift than that of H3BTB ligand.

4 Conclusions

In summary,we have reported one new four interpenetrated MOFs with H3BTB ligand.Crystal structure studies reveal that neutral DMF molecules and cationic H2NMe2+are enveloped in the channel along b axis.Fluorescent measurement shows the position of emission peak at 361 nm in 1 occurs to more blue shift than that of H3BTB ligand(396 nm),due to destroyed delocalized π-type bonds of 1.Further,an interesting temperature-dependent conductive property was also identified.The obtained conductance at 20°C is 0.36×10－6S·cm－1at 20°C.As the temperature increases, the conductance value increases and reaches the maximum of 2.24×10－5S·cm－1at 160°C.However,after then,the conductance value sharply reduces until the value of 1.14×10－5S·cm－1at 200°C.That can be attributed to the transport of H2NMe2+ions in the channel of MOFs.

Acknowledgment:We also very thank Prof.LONG La-Sheng and Dr.ZHAO Hai-Xia of Xiamen University for technological supports and kind discussion.

Supporting Information:Crystal date,selective bond length and bond angle,PXRD and UV-Vis result have been included.This information is available free of charge via the internet at http:// www.whxb.pku.edu.cn.CCDC-1043835(for 1)contains the supplementary crystallographic data for this paper.These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/data_request/cif.

(1)(a)Long,J.R.;Yaghi,O.M.Chem.Soc.Rev.2009,38(5), 1213.doi:10.1039/b903811f (b)Eddaoudi,M.;Kim,J.;Rosi,N.;Vodak,D.;Wachter,J.; O′Keeffe,M.;Yaghi,O.M.Science 2002,295(5554),469. doi:10.1126/science.1067208

(2)(a)Li,J.R.;Sculley,J.;Zhou,H.C.Chem.Rev.2012,112(2), 869.doi:10.1021/cr200190s (b)Zlotea,C.;Phanon,D.;Mazaj,M.;Heurtaux,D.;Guillerm, V.;Serre,C.;Horcajada,P.;Devic,T.;Magnier,E.;Cuevas,F.; Ferey,G.;Llewellyn,P.L.;Latroche,M.Dalton Trans.2011, 40(18),4879.doi:10.1039/c1dt10115c (c)Haldoupis,E.;Nair,S.;Sholl,D.S.J.Am.Chem.Soc.2012, 134(9),4313.doi:10.1021/ja2108239 (d)Nijem,N.;Wu,H.H.;Canepa,P.;Marti,A.;Balkus,K.J.; Thonhauser,T.;Li,J.;Chabal,Y.J.J.Am.Chem.Soc.2012, 134(37),15201.doi:10.1021/ja305754f (e)Zeng,M.H.;Yin,Z.;Tan,Y.X.;Zhang,W.X.;He,Y.P.; Kurmoo,M.J.Am.Chem.Soc.2014,136(12),4680. doi:10.1021/ja500191r

(3)(a)Hwang,Y.K.;Hong,D.Y.;Chang,J.S.;Jhung,S.H.;Seo, Y.K.;Kim,J.;Vimont,A.;Daturi,M.;Serre,C.;Ferey,G. Angew.Chem.Int.Ed.2008,47(22),4144.doi:10.1002/ anie.200705998 (b)Stock,N.;Biswas,S.Chem.Rev.2012,112(2),933. doi:10.1021/cr200304e (c)Basdogan,Y.;Keskin,S.CrystEngComm 2015,17(2),261. doi:10.1039/c4ce01711k

(4)(a)Li,B.Y.;Zhang,Y.M.;Ma,D.X.;Li,L.;Li,G.H.;Li,G. D.;Shi,Z.;Feng,S.H.Chem.Commun.2012,48(49),6151. doi:10.1039/c2cc32384b (b)Lee,J.;Farha,O.K.;Roberts,J.;Scheidt,K.A.;Nguyen,S. T.;Hupp,J.T.Chem.Soc.Rev.2009,38(5),1450.doi:10.1039/ b807080f (c)Ou,S.;Wu,C.D.Inorganic Chemistry Frontiers 2014,1 (10),721.doi:10.1039/C4QI00111G (d)Xamena,F.;Abad,A.;Corma,A.;Garcia,H.J.Catal.2007, 250(2),294.doi:10.1016/j.jcat.2007.06.004

(5)(a)Jia,L.N.;Hou,L.;Wei,L.;Jing,X.J.;Liu,B.;Wang,Y.Y.; Shi,Q.Z.Cryst.Growth Des.2013,13(4),1570.doi:10.1021/ cg3011310y (b)Burrows,A.D.CrystEngComm 2011,13(11),3623. doi:10.1039/c0ce00568a

(6)(a)Zheng,Y.Z.;Tong,M.L.;Zhang,W.X.;Chen,X.M. Angew.Chem.Int.Ed.2006,45(38),6310.doi:10.1002/ anie.200601349 (b)Ruan,C.Z.;Wen,R.;Liang,M.X.;Kong,X.J.;Ren,Y.P.; Long,L.S.;Huang,R.B.;Zheng,L.S.Inorg.Chem.2012,51 (14),7587.doi:10.1021/ic3003299 (c)Zeng,M.H.;Wu,M.C.;Liang,H.;Zhou,Y.L.;Chen,X. M.;Ng,S.W.Inorg.Chem.2007,46(18),7241.doi:10.1021/ ic700832w (d)Pinkowicz,D.;Podgajny,R.;Nowicka,B.;Chorazy,S.; Reczynski,M.;Sieklucka,B.Inorg.Chem.Front.2015,2(1), 10.doi:10.1039/C4QI00189C (e)Peng,J.B.;Zhang,Q.C.;Kong,X.J.;Zheng,Y.Z.;Ren,Y. P.;Long,L.S.;Huang,R.B.;Zheng,L.S.;Zheng,Z.P.J.Am. Chem.Soc.2012,134(7),3314.doi:10.1021/ja209752z

(7)(a)Rogez,G.;Viart,N.;Drillon,M.Angew.Chem.Int.Ed. 2010,49(11),1921.doi:10.1002/anie.200906660 (b)Batten,S.R.;Robson,R.Angew.Chem.Int.Ed.1998,37 (11),1460.doi:10.1002/(sici)1521(19980619)37:11<1460::aidanie1460>3.0.co;2-z (c)Chen,W.X.;Xu,H.R.;Zhuang,G.L.;Long,L.S.;Huang, R.B.;Zheng,L.S.Chem.Commun.2011,47(43),11933. doi:10.1039/c1cc14702a (d)Wu,B.;Lin,X.;Ge,L.;Wu,L.;Xu,T.Chem.Commun. 2013,49(2),143.doi:10.1039/C2CC37045J (e)Bonhote,P.;Dias,A.P.;Papageorgiou,N.; Kalyanasundaram,K.;Gr?tzel,M.Inorg.Chem.1996,35(5), 1168.doi:10.1021/ic951325x (f)Sadakiyo,M.;Oˉkawa,H.;Shigematsu,A.;Ohba,M.; Yamada,T.;Kitagawa,H.J.Am.Chem.Soc.2012,134(12), 5472.doi:10.1021/ja300122r (g)Zeng,M.H.;Wang,Q.X.;Tan,Y.X.;Hu,S.;Zhao,H.X.; Long,L.S.;Kurmoo,M.J.Am.Chem.Soc.2010,132(8), 2561.doi:10.1021/ja908293n (h)Chae,H.K.;Siberio-Perez,D.Y.;Kim,J.;Go,Y.; Eddaoudi,M.;Matzger,A.J.;O'Keeffe,M.;Yaghi,O.M. Nature 2004,427(6974),523.doi:10.1038/nature02311 (i)Akutagawa,T.;Koshinaka,H.;Sato,D.;Takeda,S.;Noro,S. I.;Takahashi,H.;Kumai,R.;Tokura,Y.;Nakamura,T.Nat. Mater.2009,8(4),342.doi:10.1038/nmat2377 (j)Armand,M.;Endres,F.;MacFarlane,D.R.;Ohno,H.; Scrosati,B.Nat.Mater.2009,8(8),621.doi:10.1038/nmat2448 (k)Bureekaew,S.;Horike,S.;Higuchi,M.;Mizuno,M.; Kawamura,T.;Tanaka,D.;Yanai,N.;Kitagawa,S.Nat.Mater. 2009,8(10),831.doi:10.1038/nmat2526

(8)(a)Liu,Y.;Xuan,W.M.;Cui,Y.Adv.Mater.2010,22(37), 4112.doi:10.1002/adma.201000197 (b)Yang,H.;Sang,R.L.;Xu,X.;Xu,L.Chem.Commun.2013, 49(28),2909.doi:10.1039/c3cc40516h (c)Liu,G.X.;Xu,H.;Zhou,H.;Nishihara,S.;Ren,X.M. CrystEngComm 2012,14(5),1856.doi:10.1039/c1ce05369h

(9)(a)Chen,B.;Wang,L.;Xiao,Y.;Fronczek,F.R.;Xue,M.;Cui, Y.;Qian,G.Angew.Chem.Int.Ed.2009,48(3),500. doi:10.1002/anie.200805101 (b)Kreno,L.E.;Leong,K.;Farha,O.K.;Allendorf,M.;Van Duyne,R.P.;Hupp,J.T.Chem.Rev.2012,112(2),1105. doi:10.1021/cr200324t (c)Rocha,J.;Carlos,L.D.;Paz,F.A.A.;Ananias,D.Chem. Soc.Rev.2011,40(2),92.doi:10.1039/C0CS00130A (d)Liu,Y.;Pan,M.;Yang,Q.Y.;Fu,L.;Li,K.;Wei,S.C.;Su, C.Y.Chem.Mater.2012,24(10),1954.doi:10.1021/ cm3008254 (e)Jiang,H.L.;Tatsu,Y.;Lu,Z.H.;Xu,Q.J.Am.Chem.Soc. 2010,132(16),5586.doi:10.1021/ja101541s (f)Lee,C.Y.;Farha,O.K.;Hong,B.J.;Sarjeant,A.A.; Nguyen,S.T.;Hupp,J.T.J.Am.Chem.Soc.2011,133(40), 15858.doi:10.1021/ja206029a (g)Wei,Z.W.;Gu,Z.Y.;Arvapally,R.K.;Chen,Y.P.; McDougald,R.N.;Ivy,J.F.;Yakovenko,A.A.;Feng,D.W.; Omary,M.A.;Zhou,H.C.J.Am.Chem.Soc.2014,136(23), 8269.doi:10.1021/ja5006866

(10)(a)Delley,B.J.Chem.Phys.1990,92(1),508.doi:10.1063/ 1.458452 (b)Delley,B.J.Chem.Phys.1991,94(11),7245.doi:10.1063/ 1.460208 (c)Delley,B.J.Chem.Phys.2000,113(18),7756. doi:10.1063/1.1316015

(11)Monkhorst,H.J.;Pack,J.D.Phys.Rev.B 1976,13(12),5188.

(12)Perdew,J.P.;Burke,K.;Ernzerhof,M.Phys.Rev.Lett.1996,77 (18),3865.

(13)Dolg,M.;Wedig,U.;Stoll,H.;Preuss,H.J.Chem.Phys.1987, 86(2),866.doi:10.1063/1.452288

(14)Gale,J.D.;Rohl,A.L.Mol.Simul.2003,29(5),291. doi:10.1080/0892702031000104887

(15)Addicoat,M.A.;Vankova,N.;Akter,I.F.;Heine,T.J.Chem. Theory Comput.2014,10(2),880.doi:10.1021/ct400952t

(16)Rao,K.P.;Higuchi,M.;Duan,J.;Kitagawa,S.Cryst.Growth Des.2013,13(3),981.doi:10.1021/cg301476p

Temperature-Dependent Conductivity,Luminescence and Theoretical Calculations of a Novel Zn(II)-Based Metal-Organic Framework

GAO Yi-Fen ZHUANG Gui-Lin*BAI Jia-Qi ZHONG Xing WANG Jian-Guo*
(College of Chemical Engineering,Zhejiang University of Technology,Hangzhou 310032,P.R.China)

Anovel four-fold interpenetrating metal-organic framework(MOF)(1)was obtained following reaction between Zn2+and benzene-1,3,5-tribenzoate(H3BTB).Single crystal analysis demonstrated that the framework featured a three-dimensional(10,3)net anionic framework with dimethyl formamide(DMF)and H2NMe2+encapsulated in channels along the b axis.Alternating current impedance measurements revealed an unusual temperature-dependent conductance.As the temperature was increased from 20°C the conductance value increased from 0.36×10－6S·cm－1to a maximum value of 2.24×10－5S·cm－1at 160°C,and then began to decrease.A combination of molecular dynamics(MD)simulations and dielectric property measurements demonstrated that this conductance behavior could be attributed to the synergic effect of the enhanced mobility of thecation and removal of DMF as the temperature was increased.Furthermore,the transporting energy barrier was determined to be 0.20 eV,which confirmed that the conductance was caused by proton conductivity.This work indicated that the confinement ofwithin the pores of MOFs is a promising method to induce electrical conductivity.Interestingly,the emission peak of 1 was blue-shifted when compared with that of H3BTB.Density functional theory(DFT)calculations revealed that this phenomenon was caused by the disruption of delocalized π-bonds within the BTB3－ligand in 1.

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10.3866/PKU.WHXB201610103www.whxb.pku.edu.cn

Received:July 1,2016;Revised:October 10,2016;Published online:October 10,2016.

*Corresponding authors.ZHUANG Gui-Lin,Email:glzhuang@zjut.edu.cn;Tel:+86-571-88871037.WANG Jian-Guo,Email:jgw@zjut.edu.cn; Tel:+86-571-88871037.

The project was supported by the National Key Basic Research Program of China(973)(2013CB733501)and National Natural Science Foundation of China(21176221,21136001,21671172,21306169,91334013).

國家重點基礎研究發展規劃項目(973)(2013CB733501)和國家自然科學基金(21176221,21136001,21671172,21306169,91334013)資助

?Editorial office ofActa Physico-Chimica Sinica