• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    非血紅素鐵(III)活化氧分子反應(yīng)的自旋軌道耦合和零場(chǎng)分裂

    2013-09-17 06:58:54呂玲玲王小芳朱元成劉新文王永成
    物理化學(xué)學(xué)報(bào) 2013年8期
    關(guān)鍵詞:西北師范大學(xué)化工學(xué)院天水

    呂玲玲 王小芳 朱元成 劉新文 袁 焜 王永成

    (1天水師范學(xué)院生命科學(xué)與化學(xué)學(xué)院,甘肅天水741001;2西北師范大學(xué)化學(xué)化工學(xué)院,蘭州730070)

    1 Introduction

    The mononuclear non-heme iron enzymes are an important group with a diverse range of chemical reactions including dioxygenation,hydroxylation,ring closure,oxidative desatura-tion,and aromatic ring cleavage.1Within this broad class,the oxygen-activating enzymes are one of the most extensively studied fields.1-4Most non-heme oxygenases catalyze O2activation using a high spin Fe(II)site through a redox process that also involves the substrate to provide the required number of electrons.By contrast,a small group of non-heme iron enzymes perform a high spin Fe(III)site to activate substrate for direct attack by O2,such as the lipoxygenases and intradiol dioxygenases.

    Protocatechuate 3,4-dioxygenase(3,4-PCD)is one of the intradiol dioxygenase family.It catalyzes the ring cleavage of protocatechuate(PCA)to form β-carboxy-cis,cis-muconate,with the incorporation of both oxygen atoms from molecular oxygen.Based on different electronic descriptions of the enzyme-substrate(ES)complex,various mechanisms1have been proposed for the initial O2binding and activation steps,but they have not been definitively observed,therefore are not well understood.Mechanism forcatecholring cleavage by non-heme iron intradiol dioxygenases has been computationally investigated using density functional theory(DFT)by Borowski and Siegbahn.5In 2003,Deeth and Bugg6have also reported the studied results for the extradiol cleavage mechanism.But,in these investigations,the electronic structures and intersystem crossing processes of the initial O2binding complexes have not been discussed in detail.

    However,we know that the chemistry of transition metals and their compounds(especially,metal-containing enzymes complexes such as cytochromes P450 and non-heme iron)is strongly influenced by the availability of multiple low-lying electronic states in these species.7-9Shaik and co-workers10have proposed that multiple spin states play an important role in these reactions,with many of them involving what they have called“two-state reactivity(TSR)”.The initial complexes of the triplet ground state O2(S=1)bound to Fe(III)(S=5/2)of 3,4-PCD-PCA can have a total spin of S=7/2,S=5/2,or S=3/2,and form the different spin state complexes.This means that the reactions should involve spin-conserving and spin-inversion processes.These will result in the complexity of the reaction mechanism.

    Therefore,detailed analyses of electronic structures and intersystem crossing processes in the initial complexes are very important in order to better understand the O2activation mechanism.In present paper we computed electronic exchange coupling(J)and zero-field splitting(ZFS)using qausi-restricted theory at the DFT level11implemented with the program ORCA.12Then spin-orbit coupling(SOC)matrix elements were obtained by the approximate one-electron spin-orbit Hamiltonian.13Some very meaningful conclusions have been obtained by these calculations.

    2 Computational details

    2.1 Step of the system

    The activate-site geometric structure of 3,4-PCD-PCA was obtained from the averaged crystallographic coordinate of P.putida 3,4-PCD complex with PCA(PDB code 3PCA).14Hydrogen atoms were placed at standard bond lengths and angles.Optimize calculations were performed on a model of the triplet state O2(S=1)bound to 3,4-PCD-PCA involving two Me-imidazoles to model His460 and His462,4-Me-phenolate to model Tyr408,and a bidentate PCA in the fully deprotonated state,which is shown in Scheme 1.

    Unrestricted calculations allow α and β electrons to occupy orbitals with different spatial localizations and,can describe the spin localized on two different paramagnetic centers.Therefore,density functional theory calculations were performed using the Gaussian 03 program15with spin-unrestricted functional U-BP86 with 10%Hartree-Fock exchange and the Pople triple-ζ basis set,6-311G(d)to optimize geometry of the active model described above.For comparison,calculations were also performed with the spin-unrestricted U-B3LYP functional with the LanL2DZ effective core potential basis set.Transition state structures were found to have one imaginary frequency,which correlated to the motion of the bond being broken or formed.

    2.2 Calculations of zero-field splitting(ZFS)tensor

    In the absence of nuclear spins and exchange interactions,the effective spin Hamiltonian of these interactions is usually written as

    where HZeis Zeeman effect operator,HZFSis zero-field splitting operator,βBis the Bohr magneton,B is the magnetic flux density,S is the effective spin operator,and g and D are the g-tensor and ZFS-tensor,respectively.Hspinacts on the basis functions|SM〉with M=S,S-1,…,-S.If we choose a coordinate system that diagonalizes D,HZFScan be rewritten:

    Scheme 1 Active-site geometric structures of 3,4-PCD-PCA(PDB code 3PCA)

    Thus,the ZFS is uniquely defined by the parameters D and E and the tensor orientation.Typically,D and E/D are given in a coordinate system that fulfils the following condition:

    DFT calculations of the ZFS were carried out using qausirestricted theory11by the ORCA program.12Previous studies11have investigated the dependences of the g-tensor and ZFS on the exchange-correlation functional.Thus,in this work,we obtain ZFS parameters(D and E)from additional single-point calculations using 6-311G(d)basis sets and the BP86 GGA functional.We use a recently described SOC operator that efficiently implements a spin-orbit mean-field(SOMF)method.16

    2.3 Spin-orbit coupling and exchange coupling calculations

    Exchange coupling constants(J)are calculated using the Yamaguchi formula,which covers consistently the whole range of situations from the strong to the weak exchange coupling limit:17,18

    where EHSand EBSaccount for the energies of the high-spin and broken-symmetry states,respectively;〈S2〉HSand〈S2〉BSdenote the spin angular momentum calculated in the high-spin and broken-symmetry solutions,respectively.These calculations were performed with a development version of the ORCA program.12

    In addition,in order to obtain the more detailed SOC matrix elements,the SOC calculations of the sextet and quartet states were studied using the approximate one-electron spin-orbit Hamiltonian(hi)13given in Eq.(4):

    where Likand Siare the orbital and spin angular momentum operators for electron i in the framework of the nuclei indexed k,respectively,andZ*kis the effective nuclear charge,rikis the distance of between each electron samples(i)and all nuclei(k).One-electron SOC calculations were carried out using the GAMESS program.19

    3 Results and discussion

    3.1 Initial complex electronic states

    The optimized geometries and energetic data for the octet,sextet,and quartet electronic states are depicted in Fig.1,in order to keep the discussion more simple,the goal complex,denoted as 1,is initially formed as 3,4-PCD-PCA and O2collide end-on with each other,where the superscripts denote the spin multiplicities(81,61,and41).

    3.1.1 Octet state(S=7/2)

    The singly occupied molecular orbitals(SOMOs)of81 are plotted in Fig.2 and It clearly shows that O2has two unpaired electrons,O2π*(y)and π*(z),while five others reside on the ferrous Fe(III)center,namely occupy five d orbitals,thus forming a high-spin(HS)Fe(III)(S=5/2)combined ferromagnetically with a triplet O2(S=1).Therefore the octet81 is approximately understood as van der Waals complex,which involves O2in a end-on orientation with a long Fe―O bond length of about 0.2558 nm at the U-B3LYP/LanL2DZ level(0.2487 nm for U-BP86/6-311G*),as shown in Fig.1.

    3.1.2 Sextet state(S=5/2)

    We obtained a sextet61 complex as shown in Fig.1.Compared with81,the Fe―O bond length was shortened to 0.1906 nm for U-BP86/6-311G*,while the O―O bond length was increased to 0.1281 nm.These show that O2and Fe center has obvious chemically bonded effect in the sextet61 complex.The electronic structure of61 is schematically shown in Fig.3.It is seen that O2is a superoxide,having a singly occupied O2π*(y),which is vertical to the Fe―OO plane,while the other doubly occupied π*(z)[π*(z)is in Fe―OO plane]forms a two-electron bond with the iron dz2orbital.61 has an ferromagnetically coupling of the S=1/2 superoxo anion O-2with S=2 Fe(IV)center.81 as zero reference,the U-BP86 calculated relative energy of61 is-12.14 kJ·mol-1.

    3.1.3 Quartet state(S=3/2)

    For the quartet state41,in contrast with the sextet61 case,one pronounced difference is that the Fe(IV)center has two singly occupied orbitals(dxyand π*xz,S=1),that is,41 differs from61 by a spin-flip of the a singly occupied orbital from σx2-y2to dyz,consequently,dyzis doubly occupied.O2(S=1/2)is still a superoxide with a singly occupied π*(y)and a doubly occupied π*(z)orbitals,and coupled ferromagnetically with the Fe(IV)(S=1),thus formed an intermediate-spin S=3/2 complex,41.The U-BP86 calculated energy difference is 9.21 kJ·mol-1relative to the61 state.

    3.2 Intersystem crossing process of initial complexes

    As has been already discussed before,the triplet O2(S=1)mixes with Fe(III)(S=5/2)resulting in the different spin states with a total spin of S=7/2,S=5/2,or S=3/2,and smaller energy differences among them.Moreover,we found that the spin states from the octet to quartet state are changed with the decrease of the Fe―O bond length(from 0.2487 to 0.1895 nm at the U-BP86/6-311G*level),and the sextet61 is the most stable as shown in Fig.4.In this respect,the interesting question is raised:how is the intersystem crossing of the different spin states happened?

    3.2.1 Exchange coupling(J)

    Fig.1 Selected bond lengths(nm)and energies(listed under the structures)obtained from the key point optimizations at the U-BP86/6-311G(d)and U-B3LYP/LanL2DZ levels(in the parentheses)

    Let us turn to discuss this question now,starting from the octet state81.To identify some main atomic orbital interactions,the main antiferromagnetic orbital interactions of81 were also inferred from overlaps calculated from the broken-symmetry wave function(U-BP86/6-311G*),the results calculated are plotted in Fig.5.In general,the broken-symmetry orbitals of different spin indexes(i.e.,α or β)are not orthogonal to each other and are localized on Fe(?iα)or O2(?jβ).Therefore,to this extent,the overlaps Sij=〈?jα|?jβ〉are intimately related to the strength of antiferromagnetic spin coupling.As seen from Fig.5,the overlap between the localized Fe dz2and O2π*(z),129α and 129β,is considerably better and Sij=〈129α|129β〉=0.3758 at the Fe―O distance of 0.2487 nm.The low spin coupling between 129α and 129β electron pair is therefore strong enough to lead to a Fe―O bonding.By contrast,the other overlap S=〈130α|130β〉of the Fe dyzand O2π*(y)is much weaker and Sij=0.0868.Thus the magnitude of the overlaps strongly suggested that the first Fe dz2:O2π*(z)was clearly dominant ex-change pathway,whereas Fe dyz:O2π*(y)contributed to a lesser extent and was fairly comparable.At the same time,we found that the overlaps are increased with the decrease of the Fe―O bonding,and the change of the exchange coupling constant J is very similar to that of the overlaps,the J values are increased from-20.8 to-81.4 cm-1with the distance of the Fe―O bonding from 0.2487 to 0.2200 nm.These calculations provided a detailed approximation to antiferromagnetism induced by Fe dz2:O2π*(z)delocalization.

    Fig.2 Electronic configuration of the octet state81

    Fig.3 Occupied active natural orbitals of61 at the BP86/6-311G(d)level

    Fig.4 Schematic representation of calculated reaction paths at the B3LYP/LanL2DZ level

    Therefore the formation of61 from81 is most likely due to the electron exchange induced enhanced intersystem crossing(EISC).20Certainly,for antiferromagnetic exchange,the energy gap between61 and81 is also very important.The energy gap between these two states is about 12.14 kJ·mol-1,one might expect that EISC would be faster.The electron exchange interaction between Fe(III)(S=5/2)and O2(S=1)serves as the first-order perturbation that drives EISC.The magnitude of this perturbation,and thus the overall intersystem crossing rate,depends strongly on the electronic overlap between the orbitals that contribute to the singly occupied molecular orbitals(SOMO)of the Fe(III)(S=5/2)center and O2(S=1).

    In addition,antiferromagnetic exchange coupling can lead to the partly forming of41 due to the weaker overlap S=〈130α|130β〉.We also noted that the quartet wave function can have some admixture of the sextet wave function.The effect was more noticeable,the expectation value of the total spin operator after annihilation,〈S2〉=5.47 was far from the value expected for a pure quartet state,〈S2〉=3.75.Based on the following expressions for the spin expectation values of the contaminated quartet state:18

    where C is the configuration coefficient,S is the total spin operator,subscripts 6 and 4 denote sextet state and quartet state,respectively.From Eq.(5)we obtain the contribution of the quartet state which is about 67%of the mixing states.This reason is that a second-order term of ZFS,SOC)introduces some angular momentum into the sextet state.These mechanisms above are described in Fig.3.

    3.2.2 Zero-field splitting(ZFS)

    Fig.5 Pathways of the exchange coupling from81 to61 or41

    The net effects for ZFS are to introduce a splitting of the 2S+1,in the absence of an external magnetic field.This will main-ly attribute to the ZFS?s two contributions:11(a)a first-order term,the direct dipolar spin-spin(SS)interaction between pairs of electrons and(b)a second-order term,arising from SOC.Thus an analysis and interpretation of the ZFS is imperative in this study.

    BP86 calculations were performed to determine the signs of the D and E values for61.The ZFS parameters[D=Dzz-1/2(Dxx+Dyy),E=1/2(Dxx-Dyy)]are calculated,D=+8.589 cm-1and E/D=+0.068.The more detailed results of the calculated ZFS using the quasi-restricted DFT method are shown in Table 1.From the results in Table 1,the major contribution arises from the second-order SOC contribution(around 97.5%of D),while the SS contributions are essentially negligible.Concerning the SOC part,it contains four significant contributions:α→α(D=0.332 cm-1),β→β(D=0.240 cm-1),α→β(D=8.138 cm-1),and β→α (D=-0.336 cm-1).However the major contribution comes from the α→β spin-flip excitation.This excitation contributes around 77.2%of the DSOCvalue,corresponding to the spin-pairing ΔS=-1(i.e.,sextet→quartet)transitions.The second larger SOC contribution arises from the β→α spin-raising ΔS=+1(sextet→octet)excitation(around 4%of DSOC)corresponding to ligand-to-metal charge-transfer transitions.The remaining two SOC contributions come from the spin allowed ΔS=0(sextet→sextet)ligand-field excitations and have usually been solely held responsible for the ZFS.However,these contributions are only around 7%compared to the DSOCvalue.

    The ΔS=-1 state(sextet is flipped to quartet state)is found to make significant contributions to DSOC,with the primary contribution arising from the single-determinant spin-paired states within the single occupied sets of orbitals,σx2-y2,π*xz,dxy,and dyz(see Fig.3).Namely,andvital spin-flip excitation.Applying the angular momentum operator to this four orbitals generates three nonzero SOC integrals:ndlz|dxy〉which make the largest contribution to the SOC and lead to the larger values of Dxx(=8.8 cm-1),Dzz(=16.8 cm-1),and Dyy(=7.6 cm-1).It identifies the origin of large ZFS as spinorbit coupling to low-lying ΔS=-1 state,and shows that the quartet41 can arise from normal spin-orbit induced intersystem crossing as compared with the weaker exchange coupling.

    3.2.3 Spin-orbit coupling

    Table 1 Contributions to the calculated zero-field splitting between spin-orbit coupling and spin-spin for the sextet state

    Based on the above analysis,the sextet61 from81 is fast formed via EISC,following the system will well change its spin multiplicities from the sextet state to the quartet ground state41 by SOC in the O2gradual approach to Fe center process.However,a spin-forbidden transition requires an effect of SOC that provides a major mechanism for the intersystem crossing process.21-24Therefore,we must inspect the orbital relationships which promote the SOC matrix elements.

    The ROHF orbitals for the construction of the quartet and sextet CASCI wave functions to be used in the SOC evaluation have been generated by the sextet ROHF calculation.At the CAS(7,6)level the dominant determinants of the MCSCF wave functions have configuration interaction(CI)coefficients of 0.98 and 0.17 for the sextet and 0.86 and-0.48 for the quartet state(configurations of less than 0.1 have not been listed).Thus the permissible approximation of the sextet wave function by a single configuration(0.98)enables us to analyze the SOC matrix elements.The quartet configuration is described as shown in Eq.(6),

    Nonzero elements of the p-components(p=x,y,z)of the SOC matrix,,are always proportional to the function,Fp,as given in Eq.(7).

    To further understand the efficient SOC,it is very important that the SOC matrix elementsandare discussed.Because the SOC constant(ξFe)is an order of magnitude greater than that of oxygen,making it a reasonable approximation to consider only the Fe contribution when discussing spin-orbit mixing with quartet states.Thus

    where the η term is the MS-depended weight weighing factor,and θ=α and/or β.In the present case,for the sextet state,the fundamental open-shell configuration has one dominant coeffi-cient,i.e.,C0=0.98≈1,while coefficients of quartet states are Cj1=0.86 and Cj2=-0.48,respectively.

    Table 2 Calculated SOC matrix elements(cm-1)in the41 structure

    Fig.6 Electronic evolution during the O―O bond cleavage

    Therefore:

    Here,only the first term is nonzero value,the electron shift from dx2-y2to dyzcreates an non-zero angular momentum in the Lx-direction,resulting in the larger SOC matrix elements as listed in Table 2.The second term is zero value due to the mismatch for the dx2-y2→dyztransition with Lzangular momentum direction.Similarly,the larger z-direction SOCs come from〈dx2-y2│LFe,z│dxy〉〈α│Sz│α〉coupling of the second term in Eq.(9).These analyses are in good agreement with the SOC calculations of the approximate one-electron spin-orbit Hamiltonian(see Table 2)and D-tensor of ZFS,25namely there exist the larger SOC matrix elements in Lx-and Lz-directions,resulting in the SOC constant of 353.16 cm-1.These also further indicated that the significant contributions to D arise from the ΔS=-1 spin-flip transition,and the quartet state41 is produced by a spin-orbit coupling intersystem crossing.

    3.3 Cleavage process of the O―O bond

    Structural parameters of the transition state(4TS)on the quartet surface are collected in Fig.1.The O―O bond cleavage pathway is shown in Fig.6.The O―O bond activation takes place through a precursor intermediate42 and transition state(4TS),to afford a cleavage product4P.The4TS has the feature of partially broken O―O bond(0.1687 nm),in which the activation barrier is 111.37 kJ·mol-1with respect to42.4TS is characterized as a transition structure by one imaginary frequency of 839.7i cm-1,and the vibrational vector corresponds to the expected components of the reaction coordinate,i.e.,breaking of the O―O bond.

    Schematic of the frontier molecular orbitals which participate in the three-electron transfer process upon the O―O bond cleavage is shown in Fig.6.As can been seen from Fig.6,the doubly occupied PCA π orbital is the HOMO in the complex,one electron from the doubly occupied PCA π orbital can be donated directly to the O2π*orbital to form the distorted O―CPCAbond.Two electrons are transferred to the O2π*orbital generating a Fe(IV)-peroxide.There is the strong covalent interaction between the PCA HOMO and Fe dxzorbitals in the α manifold,the second electron of the PCA HOMO is transferred to Fe,at the same time the transfer of an Fe d electron into the O2σ*orbital to break the O―O bond is accomplished.Finally,cleavage of the O―O bond leads to formation of an Fe(IV)-oxo.Therefore,the transfer of these three electrons(one α and two β)shows that the Fe center acts as a buffer to transfer an electron pair from PCA π orbital to the triplet O2in the spin forbidden reaction.

    4 Conclusions

    The O2activating mechanism by non-heme iron enzyme,3,4-PCD-PCA,has been studied using theoretical calculations.The electronic structure origins and intersystem crossing of the different spin states(a total spin of S=7/2,S=5/2,or S=3/2)were discussed by the broken-symmetry method and SOC mechanism.The octet state81 is stable with the aid of the electrostatic interaction,while the ultrafast formation of61 is most likely due to EISC.As for the formation of the quartet state41 from the sextet61,there coexist the two effects,electron spin exchange coupling and spin-orbit coupling in the sextet61.As a driving force of spin conversion the exchange interaction competes with spin-orbit coupling interaction.The calculated results show that the latter is the dominant factor due to the larger SOC constant(353.16 cm-1).The doublet21 optimization is failure using various DFT methods,all optimizations can not be converged due to the energy fluctuation.

    The O―O bond activation takes place through a precursor intermediate42 and transition state(4TS),to afford a cleavage product4P.The electronic transfer of the PCA HOMO is the vital role for the cleavage of the O―O bond.The Fe center of non-heme enzyme is a buffer to transfer an electron pair from PCAHOMO orbital to the O2in the reaction.

    (1)Pau,M.Y.M.;Davis,M.I.;Orville,A.M.;Lipscomb,J.D.;Solomon,E.I.J.Am.Chem.Soc.2007,129,1944.doi:10.1021/ja065671x

    (2) Costas,M.;Mehn,M.P.;Jensen,M.P.;Que,L.,Jr.Chem.Rev.2004,104,939.doi:10.1021/cr020628n

    (3) Solomon,E.I.;Brunold,T.C.;Davis,M.I.;Kemsley,J.N.;Lee,S.K.;Lehnert,N.;Neese,F.;Skulan,A.J.;Yang,Y.S.;Zhou,J.Chem.Rev.2000,100,235.doi:10.1021/cr9900275

    (4) Nam,W.Accounts Chem.Res.2007,40,522.doi:10.1021/ar700027f

    (5) Borowski,T.;Siegbahn,P.E.M.J.Am.Chem.Soc.2006,128,12941.doi:10.1021/ja0641251

    (6) Deeth,R.J.;Bugg,T.D.H.J.Biol.Inorg.Chem.2003,8,409.

    (7) Fiedler,A.;Schroder,D.;Shaik,S.;Schwarz.H.J.Am.Chem.Soc.1994,116,10734.doi:10.1021/ja00102a043

    (8)Yoshizawa,K.;Shiota,Y.;Yamabe,T.J.Chem.Phys.1999,111,538.doi:10.1063/1.479333

    (9) Shaik,S.;Hirao,H.;Kumar,D.Accounts Chem.Res.2007,40,532.doi:10.1021/ar600042c

    (10) Schroder,D.;Shaik,S.;Schwarz,H.Accounts Chem.Res.2000,33,139.doi:10.1021/ar990028j

    (11) Neese,F.J.Am.Chem.Soc.2006,128,10213.doi:10.1021/ja061798a

    (12) Neese,F.ORCA,version 2.8-20;Max-Planck Institute for Bioinorganic Chemistry:Mülheim an der Ruhr,Germany,2010.

    (13)Fedorov,D.G.;Koseki,S.;Schmidt,M.W.;Gordon,M.S.Int.Rev.Phys.Chem.2003,22,551.

    (14) Elgren,T.E.;Orville,A.M.;Kelly,K.A.;Lipscomb,J.D.;Ohlendorf,D.H.;Que,L.,Jr.Biochemistry 1997,36,11504.doi:10.1021/bi970691k

    (15) Frisch,M.J.;Trucks,G.W.;Schlegel,H.B.;et al.Gaussian 03,Revision E.01;Gaussian Inc.:Pittsburgh,PA,2003.

    (16)Hess,B.A.;Marian,C.M.;Wahlgren,U.;Gropen,O.Chem.Phys.Lett.1996,251,365.doi:10.1016/0009-2614(96)00119-4(17) Rodriguez,J.H.;McCusker,J.K.J.Chem.Phys.2002,116,6253.doi:10.1063/1.1461363

    (18)Rodriguez,J.H.;Wheeler,D.E.;McCusker,J.K.J.Am.Chem.Soc.1998,120,12051.doi:10.1021/ja980917m

    (19) Schmidtm,M.W.;Baldridge,K.K.;Boatz,J.A.;Elbert,S.T.;Gordon,M.S.;Jensen,J.H.;Koseki,S.;Matsunaga,N.;Nguyen,K.A.;Su,S.J.;Windus,T.L.;Dupuis,M.;Motgomery,J.A.J.Comput.Chem.1993,14,1347.

    (20)Giacobbe,E.M.;Mi,Q.;Colvin,M.T.;Cohen,B.;Ramanan,C.;Scott,A.M.;Yeganeh,S.;Marks,T.J.;Ratner,M.A.;Wasielewski,M.R.J.Am.Chem.Soc.2009,131,3700.doi:10.1021/ja808924f

    (21) Isobe,H.;Yamanaka,S.;Kuramitsu,S.;Yamaguchi,K.J.Am.Chem.Soc.2008,130,132.doi:10.1021/ja073834r

    (22)Dede,Y.;Zhang,X.;Schlangen,M.;Schwarz,H.;Baik,M.H.J.Am.Chem.Soc.2009,122,114.

    (23)Lv,L.L.;Wang,Y.C.;Wang,Q.;Liu,H.W.J.Phys.Chem.C 2010,114,17610.

    (24) Lü,L.L.;Wang,Y.C.Acta.Phys.-Chim.Sin.2006,22,265.[呂玲玲,王永成.物理化學(xué)學(xué)報(bào),2006,22,265.]doi:10.3866/PKU.WHXB20060302

    (25)Lü,L.L.;Zhu,Y.C.;Wang,X.F.;Zuo,G.F.;Zhao,S.R.;Guo,F.;Wang,Y.C.Chin.Sci.Bull.2013,58,627.[呂玲玲,朱元成,王小芳,左國(guó)防,趙素瑞,郭 峰,王永成.科學(xué)通報(bào),2013,58,627.]doi:10.1007/s11434-012-5316-7

    猜你喜歡
    西北師范大學(xué)化工學(xué)院天水
    使固態(tài)化學(xué)反應(yīng)100%完成的方法
    西北師范大學(xué)作品
    大眾文藝(2023年9期)2023-05-17 23:55:52
    西北師范大學(xué)美術(shù)學(xué)院作品選登
    天水嬸與兩岸商貿(mào)
    西北師范大學(xué)美術(shù)學(xué)院作品選登
    西北師范大學(xué)美術(shù)學(xué)院作品選登
    國(guó)家開放大學(xué)石油和化工學(xué)院學(xué)習(xí)中心列表
    【鏈接】國(guó)家開放大學(xué)石油和化工學(xué)院學(xué)習(xí)中心(第四批)名單
    天水地區(qū)的『秦與戎』
    重返絲綢之路—從天水到青海湖
    美食(2018年10期)2018-10-18 08:10:58
    免费大片18禁| 如何舔出高潮| 国产大屁股一区二区在线视频| 久久久久久久久中文| 99视频精品全部免费 在线| 精品人妻偷拍中文字幕| 22中文网久久字幕| 国产成人午夜福利电影在线观看| 综合色av麻豆| 中文字幕av成人在线电影| 国产成人午夜福利电影在线观看| 亚洲精品乱码久久久v下载方式| 国产日韩欧美在线精品| 午夜久久久久精精品| 91精品伊人久久大香线蕉| 少妇的逼水好多| 免费看av在线观看网站| 国产高清有码在线观看视频| 国内精品宾馆在线| 免费黄色在线免费观看| 中文乱码字字幕精品一区二区三区 | 亚洲av不卡在线观看| 18禁裸乳无遮挡免费网站照片| 搡老乐熟女国产| 国产精品久久久久久av不卡| 亚洲婷婷狠狠爱综合网| 久久精品夜夜夜夜夜久久蜜豆| 女人被狂操c到高潮| 在线观看免费高清a一片| 神马国产精品三级电影在线观看| 肉色欧美久久久久久久蜜桃 | a级毛色黄片| 天堂√8在线中文| 在线播放无遮挡| 色视频www国产| 免费观看无遮挡的男女| 亚洲最大成人av| 日本一二三区视频观看| 干丝袜人妻中文字幕| 超碰97精品在线观看| 99热网站在线观看| 免费观看av网站的网址| 国产一区二区三区综合在线观看 | 免费观看精品视频网站| or卡值多少钱| 国产有黄有色有爽视频| 精品少妇黑人巨大在线播放| 欧美97在线视频| 可以在线观看毛片的网站| 久久久欧美国产精品| 成年人午夜在线观看视频 | 亚洲av成人av| 少妇被粗大猛烈的视频| 日本与韩国留学比较| 一级a做视频免费观看| 国产综合精华液| 一级毛片电影观看| 看黄色毛片网站| 婷婷色av中文字幕| 禁无遮挡网站| 久久久色成人| 熟妇人妻不卡中文字幕| 在线观看人妻少妇| 亚洲国产最新在线播放| 日日撸夜夜添| 欧美bdsm另类| 国产av在哪里看| 街头女战士在线观看网站| 国产精品爽爽va在线观看网站| 51国产日韩欧美| 伊人久久国产一区二区| kizo精华| 韩国高清视频一区二区三区| 嫩草影院精品99| 九九久久精品国产亚洲av麻豆| 色综合亚洲欧美另类图片| 国产亚洲5aaaaa淫片| 黄片无遮挡物在线观看| 免费观看无遮挡的男女| 国产一区有黄有色的免费视频 | 国产精品爽爽va在线观看网站| 99热全是精品| 午夜激情欧美在线| 国产精品久久久久久精品电影小说 | 精品人妻偷拍中文字幕| h日本视频在线播放| 精品一区二区三卡| 免费大片黄手机在线观看| 久久精品久久久久久噜噜老黄| 亚洲精品国产成人久久av| 97热精品久久久久久| 久久久精品欧美日韩精品| 午夜福利在线在线| 免费av不卡在线播放| 肉色欧美久久久久久久蜜桃 | 一个人看视频在线观看www免费| 亚洲成人精品中文字幕电影| 一本久久精品| 国产一级毛片在线| 成人综合一区亚洲| av黄色大香蕉| 性插视频无遮挡在线免费观看| 男女国产视频网站| 美女xxoo啪啪120秒动态图| 国产欧美另类精品又又久久亚洲欧美| 欧美xxxx黑人xx丫x性爽| 99热全是精品| 午夜福利成人在线免费观看| videossex国产| 国产精品爽爽va在线观看网站| 嫩草影院精品99| 97在线视频观看| 免费观看无遮挡的男女| 老师上课跳d突然被开到最大视频| 国产精品久久久久久久电影| 日韩欧美三级三区| 日本av手机在线免费观看| av在线播放精品| 舔av片在线| 少妇猛男粗大的猛烈进出视频 | 日韩人妻高清精品专区| 天堂av国产一区二区熟女人妻| 可以在线观看毛片的网站| 中文资源天堂在线| h日本视频在线播放| 国产黄频视频在线观看| 国产成人a∨麻豆精品| 亚洲精品国产av蜜桃| a级一级毛片免费在线观看| 久久久久久久久中文| 日韩 亚洲 欧美在线| 国产淫片久久久久久久久| 国产老妇伦熟女老妇高清| 99热6这里只有精品| 国产精品美女特级片免费视频播放器| 亚洲美女搞黄在线观看| 亚洲精品aⅴ在线观看| 我要看日韩黄色一级片| 亚洲欧美中文字幕日韩二区| 国产在线一区二区三区精| 欧美 日韩 精品 国产| 69人妻影院| 男女边吃奶边做爰视频| 国产一区二区亚洲精品在线观看| 青春草亚洲视频在线观看| 亚洲精品久久午夜乱码| 国产精品久久久久久久久免| 三级国产精品欧美在线观看| 日韩av免费高清视频| 美女cb高潮喷水在线观看| 干丝袜人妻中文字幕| av国产久精品久网站免费入址| 国产国拍精品亚洲av在线观看| 有码 亚洲区| 淫秽高清视频在线观看| 女人十人毛片免费观看3o分钟| 春色校园在线视频观看| 欧美97在线视频| 免费看a级黄色片| 少妇猛男粗大的猛烈进出视频 | 久久精品熟女亚洲av麻豆精品 | 永久网站在线| 亚洲丝袜综合中文字幕| 乱码一卡2卡4卡精品| 成人午夜精彩视频在线观看| 97超碰精品成人国产| 欧美区成人在线视频| 国产av不卡久久| 99久久精品国产国产毛片| av线在线观看网站| 国产乱人偷精品视频| 久久精品国产亚洲网站| 亚洲国产色片| 干丝袜人妻中文字幕| 午夜免费观看性视频| 午夜精品一区二区三区免费看| 国产成人freesex在线| 色综合亚洲欧美另类图片| 熟女人妻精品中文字幕| 精品国产一区二区三区久久久樱花 | 国产成人精品婷婷| 精品人妻视频免费看| 在线天堂最新版资源| av在线蜜桃| 国产黄频视频在线观看| 国产一区亚洲一区在线观看| 91在线精品国自产拍蜜月| 最近2019中文字幕mv第一页| 三级男女做爰猛烈吃奶摸视频| 亚洲欧洲日产国产| 色视频www国产| 国产亚洲精品av在线| 大香蕉久久网| 亚洲欧美精品自产自拍| av天堂中文字幕网| 女人久久www免费人成看片| ponron亚洲| 亚洲欧美精品专区久久| 一本—道久久a久久精品蜜桃钙片 精品乱码久久久久久99久播 | 熟女电影av网| 亚洲精品日韩av片在线观看| 欧美性猛交╳xxx乱大交人| 日韩欧美精品免费久久| 狂野欧美白嫩少妇大欣赏| 一级毛片我不卡| 日本欧美国产在线视频| 国产精品久久久久久久久免| 人人妻人人看人人澡| 精品国产一区二区三区久久久樱花 | 26uuu在线亚洲综合色| videossex国产| 午夜免费男女啪啪视频观看| 国产永久视频网站| 国国产精品蜜臀av免费| 婷婷色综合www| 毛片一级片免费看久久久久| 久久精品久久精品一区二区三区| 女人十人毛片免费观看3o分钟| 精品一区二区三区视频在线| 欧美极品一区二区三区四区| 精品国内亚洲2022精品成人| 国产精品99久久久久久久久| 国产亚洲5aaaaa淫片| 精品久久久久久久久av| 国产成人精品婷婷| 亚洲最大成人手机在线| 亚洲天堂国产精品一区在线| 全区人妻精品视频| 国产三级在线视频| 97超视频在线观看视频| 麻豆国产97在线/欧美| 一级毛片电影观看| 欧美日韩国产mv在线观看视频 | 九九在线视频观看精品| 最近最新中文字幕免费大全7| 一本一本综合久久| 欧美丝袜亚洲另类| 人妻少妇偷人精品九色| 麻豆乱淫一区二区| 老师上课跳d突然被开到最大视频| 免费av不卡在线播放| 久久精品夜夜夜夜夜久久蜜豆| 亚洲av电影在线观看一区二区三区 | 嫩草影院入口| 日日摸夜夜添夜夜添av毛片| 亚洲国产欧美在线一区| 国产在线一区二区三区精| 亚洲精品自拍成人| 成人漫画全彩无遮挡| 禁无遮挡网站| 亚洲欧美中文字幕日韩二区| 国产黄色视频一区二区在线观看| 18禁动态无遮挡网站| 国产伦一二天堂av在线观看| 熟女电影av网| 日韩中字成人| 亚洲va在线va天堂va国产| 日韩成人伦理影院| 亚洲18禁久久av| a级毛色黄片| 亚洲经典国产精华液单| 男人舔女人下体高潮全视频| 97超视频在线观看视频| 久久久久久国产a免费观看| av在线播放精品| 美女高潮的动态| 免费看光身美女| 中文欧美无线码| 美女xxoo啪啪120秒动态图| 嘟嘟电影网在线观看| 国产精品综合久久久久久久免费| 国产在视频线精品| 亚洲成人av在线免费| 日本免费a在线| 成人一区二区视频在线观看| 久久精品久久久久久噜噜老黄| 国产亚洲精品久久久com| 一级爰片在线观看| 亚洲最大成人中文| 欧美区成人在线视频| 欧美精品一区二区大全| 日韩制服骚丝袜av| 97热精品久久久久久| 国产探花在线观看一区二区| 国产成人精品久久久久久| 少妇的逼好多水| 国产人妻一区二区三区在| 最近中文字幕2019免费版| 搡老妇女老女人老熟妇| 欧美人与善性xxx| 男女边吃奶边做爰视频| 欧美潮喷喷水| 2021天堂中文幕一二区在线观| 大片免费播放器 马上看| 欧美高清性xxxxhd video| 午夜精品一区二区三区免费看| 中文字幕久久专区| 成人毛片60女人毛片免费| 国产精品国产三级国产av玫瑰| 大香蕉97超碰在线| 精品人妻一区二区三区麻豆| 肉色欧美久久久久久久蜜桃 | 淫秽高清视频在线观看| 80岁老熟妇乱子伦牲交| 亚洲自偷自拍三级| a级毛色黄片| 一个人看的www免费观看视频| 亚洲真实伦在线观看| 日韩三级伦理在线观看| 久久久久久久久久黄片| 一级二级三级毛片免费看| 久99久视频精品免费| 日韩成人伦理影院| 美女主播在线视频| 一级毛片久久久久久久久女| 蜜桃久久精品国产亚洲av| 男女边摸边吃奶| 中文乱码字字幕精品一区二区三区 | 精品久久久久久久久av| 久久这里有精品视频免费| 国产一区亚洲一区在线观看| 国产成人a区在线观看| 亚洲伊人久久精品综合| 精品亚洲乱码少妇综合久久| 搡女人真爽免费视频火全软件| 如何舔出高潮| 少妇丰满av| 国产精品久久久久久久久免| eeuss影院久久| 色视频www国产| 2022亚洲国产成人精品| 韩国av在线不卡| 男的添女的下面高潮视频| 成人无遮挡网站| 色综合色国产| 色播亚洲综合网| 久久鲁丝午夜福利片| 在线观看美女被高潮喷水网站| 波多野结衣巨乳人妻| 丰满人妻一区二区三区视频av| 成人鲁丝片一二三区免费| 精品不卡国产一区二区三区| 日韩制服骚丝袜av| 免费观看无遮挡的男女| 蜜桃亚洲精品一区二区三区| 久久精品国产亚洲av涩爱| 五月伊人婷婷丁香| 婷婷色综合www| 欧美激情国产日韩精品一区| 久久久成人免费电影| 性色avwww在线观看| 一级毛片aaaaaa免费看小| 日韩不卡一区二区三区视频在线| 免费黄网站久久成人精品| 日本色播在线视频| 精品99又大又爽又粗少妇毛片| 欧美日韩精品成人综合77777| 久久草成人影院| 五月玫瑰六月丁香| 亚洲成人一二三区av| 日本黄大片高清| 国产成人福利小说| 亚洲一区高清亚洲精品| .国产精品久久| 欧美激情在线99| 大香蕉久久网| 国模一区二区三区四区视频| 亚洲电影在线观看av| 日本一二三区视频观看| 夫妻性生交免费视频一级片| 青春草亚洲视频在线观看| 国产成人a区在线观看| 一区二区三区高清视频在线| 91久久精品国产一区二区三区| 国产精品一区www在线观看| 国产色婷婷99| 最近中文字幕2019免费版| 国产精品一区二区三区四区久久| 人妻系列 视频| 九草在线视频观看| 免费电影在线观看免费观看| 成人鲁丝片一二三区免费| 午夜福利网站1000一区二区三区| 国产人妻一区二区三区在| 国产永久视频网站| 建设人人有责人人尽责人人享有的 | 日韩 亚洲 欧美在线| 日韩精品青青久久久久久| 日韩 亚洲 欧美在线| 亚洲精品视频女| 午夜激情福利司机影院| 亚洲真实伦在线观看| 女人被狂操c到高潮| 91av网一区二区| 成人亚洲精品av一区二区| 日韩精品有码人妻一区| 老女人水多毛片| xxx大片免费视频| 联通29元200g的流量卡| 九色成人免费人妻av| 免费黄频网站在线观看国产| 日韩伦理黄色片| 建设人人有责人人尽责人人享有的 | 久久亚洲国产成人精品v| 亚洲国产精品sss在线观看| 最近手机中文字幕大全| 高清视频免费观看一区二区 | 狂野欧美白嫩少妇大欣赏| 国产毛片a区久久久久| 我要看日韩黄色一级片| 国产探花极品一区二区| 亚洲婷婷狠狠爱综合网| 午夜福利在线观看免费完整高清在| 99久国产av精品国产电影| 欧美精品一区二区大全| 日本黄色片子视频| 3wmmmm亚洲av在线观看| 成年免费大片在线观看| 日韩人妻高清精品专区| 嫩草影院入口| 一级毛片aaaaaa免费看小| 久久精品人妻少妇| 成人漫画全彩无遮挡| 成年av动漫网址| 男女边摸边吃奶| av在线播放精品| 99久久精品一区二区三区| 日本午夜av视频| av女优亚洲男人天堂| 国内少妇人妻偷人精品xxx网站| 少妇熟女欧美另类| 国产不卡一卡二| 又爽又黄a免费视频| 777米奇影视久久| 午夜视频国产福利| 嫩草影院新地址| 免费av不卡在线播放| 久久国内精品自在自线图片| 91午夜精品亚洲一区二区三区| 国产精品国产三级国产专区5o| av国产免费在线观看| 亚洲美女搞黄在线观看| 又粗又硬又长又爽又黄的视频| 美女被艹到高潮喷水动态| 精品午夜福利在线看| 国产精品麻豆人妻色哟哟久久 | 美女cb高潮喷水在线观看| 国产精品99久久久久久久久| 3wmmmm亚洲av在线观看| 好男人在线观看高清免费视频| 国产成人一区二区在线| 在线免费观看的www视频| 亚洲一区高清亚洲精品| 亚洲激情五月婷婷啪啪| 91久久精品国产一区二区成人| 国产又色又爽无遮挡免| 夫妻午夜视频| 80岁老熟妇乱子伦牲交| 综合色丁香网| 在线a可以看的网站| 国产淫片久久久久久久久| 亚洲真实伦在线观看| 午夜精品国产一区二区电影 | 亚洲av福利一区| 在线免费观看的www视频| 秋霞伦理黄片| 日日干狠狠操夜夜爽| 99视频精品全部免费 在线| 亚洲欧美中文字幕日韩二区| av播播在线观看一区| 国产美女午夜福利| 1000部很黄的大片| 国产亚洲精品久久久com| 欧美人与善性xxx| 亚洲精品国产成人久久av| av黄色大香蕉| 国产精品无大码| 午夜精品在线福利| 国产精品.久久久| 乱人视频在线观看| 精品久久久久久久人妻蜜臀av| 国产精品人妻久久久影院| 久久草成人影院| 亚洲av中文av极速乱| 成人性生交大片免费视频hd| 亚洲精品亚洲一区二区| 免费黄网站久久成人精品| 欧美精品国产亚洲| 亚洲,欧美,日韩| 97热精品久久久久久| 精品人妻偷拍中文字幕| 狠狠精品人妻久久久久久综合| 黑人高潮一二区| 中文资源天堂在线| 69av精品久久久久久| 亚洲av二区三区四区| 久久97久久精品| 伊人久久精品亚洲午夜| 国产国拍精品亚洲av在线观看| 成人亚洲精品av一区二区| 寂寞人妻少妇视频99o| 一二三四中文在线观看免费高清| 天堂av国产一区二区熟女人妻| www.色视频.com| 精品一区二区三区视频在线| h日本视频在线播放| 校园人妻丝袜中文字幕| 日韩,欧美,国产一区二区三区| 精品久久久精品久久久| 日产精品乱码卡一卡2卡三| 直男gayav资源| 九色成人免费人妻av| 亚洲最大成人中文| 五月天丁香电影| 欧美区成人在线视频| 插阴视频在线观看视频| 99久久九九国产精品国产免费| 两个人视频免费观看高清| 国产成人一区二区在线| 青青草视频在线视频观看| 小蜜桃在线观看免费完整版高清| 天堂√8在线中文| 直男gayav资源| 中文欧美无线码| 能在线免费观看的黄片| 99视频精品全部免费 在线| 啦啦啦中文免费视频观看日本| 国产午夜精品论理片| 亚洲精品国产成人久久av| 国产激情偷乱视频一区二区| 色哟哟·www| 一级爰片在线观看| 99久久精品热视频| 熟妇人妻不卡中文字幕| 又大又黄又爽视频免费| 一级爰片在线观看| 啦啦啦中文免费视频观看日本| 三级国产精品欧美在线观看| 99久国产av精品| 久久久国产一区二区| 国产成人freesex在线| 国内精品宾馆在线| 亚洲精品成人久久久久久| 大又大粗又爽又黄少妇毛片口| 国产高清有码在线观看视频| 91久久精品电影网| 高清毛片免费看| 亚洲精品国产成人久久av| 国产高清不卡午夜福利| 国产精品一二三区在线看| av免费在线看不卡| 熟妇人妻久久中文字幕3abv| 亚洲精品日本国产第一区| 日韩中字成人| 欧美一级a爱片免费观看看| 精品久久国产蜜桃| 久久亚洲国产成人精品v| 天美传媒精品一区二区| 午夜免费男女啪啪视频观看| av在线天堂中文字幕| 免费人成在线观看视频色| 国产精品一区二区三区四区久久| 男女那种视频在线观看| 国产精品久久久久久精品电影| 亚洲精品一区蜜桃| 久久精品夜夜夜夜夜久久蜜豆| 国产久久久一区二区三区| 美女国产视频在线观看| 伊人久久国产一区二区| 99热网站在线观看| 大又大粗又爽又黄少妇毛片口| 2018国产大陆天天弄谢| 精品少妇黑人巨大在线播放| 久久久久精品性色| 久久久成人免费电影| 亚洲无线观看免费| 好男人在线观看高清免费视频| 久久精品久久久久久噜噜老黄| 国产午夜精品一二区理论片| 久久久久九九精品影院| 亚洲成人中文字幕在线播放| 秋霞伦理黄片| 一区二区三区乱码不卡18| 精品人妻视频免费看| 可以在线观看毛片的网站| 欧美xxxx黑人xx丫x性爽| 黄片无遮挡物在线观看| 免费人成在线观看视频色| 久久午夜福利片| 欧美日韩在线观看h| 可以在线观看毛片的网站| 97热精品久久久久久| 深夜a级毛片| 99久久精品一区二区三区| 一级毛片我不卡| 97人妻精品一区二区三区麻豆| 免费人成在线观看视频色| videossex国产| 亚洲国产精品sss在线观看| 99久久精品一区二区三区| 精品久久久精品久久久| 亚洲精品成人久久久久久| 国产午夜精品一二区理论片| 99久久精品国产国产毛片| 久久久久精品久久久久真实原创| 97超碰精品成人国产| 国产精品嫩草影院av在线观看| 亚洲av成人精品一二三区| 亚洲性久久影院| 人妻少妇偷人精品九色| 免费观看a级毛片全部| 老师上课跳d突然被开到最大视频| 男女边吃奶边做爰视频| 国产伦理片在线播放av一区| 在线观看美女被高潮喷水网站|