• <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 ?

    Freezing the conductance of platinum(II) complexes by quantum interference effect

    2022-07-11 03:39:46SaiSaiYanJinYunWangZiYouPanDaShengZhengQianChongZhangZhongNingChen
    Chinese Chemical Letters 2022年6期

    Sai-Sai Yan,Jin-Yun Wang,Zi-You Pan,Da-Sheng Zheng,Qian-Chong Zhang,c,?,Zhong-Ning Chen,c,?

    a Fujian Normal University,Fuzhou 350007,China

    b State Key Laboratory of Structural Chemistry,Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences,Fuzhou 350002,China

    c Fujian Science &Technology Innovation Laboratory for Optoelectronic Information of China,Fuzhou 350108,China

    Keywords:Platinum(II) complex Electronic effect Single-molecule conductance Quantum interference Magic ratio rule

    ABSTRACT Understanding the impact of substituents on the quantum interference effect at single molecule scale is of great importance for the design of molecular devices.In this work,three platinum(II) complexes with–H,–NH2 and –NO2 groups on conductive backbones were designed and synthesized.Single-molecule conductance,which was measured using scanning tunnelling microscope break junction (STM-BJ) technique,demonstrated a conductance freeze phenomenon under the variation of substituents.Theoretical study revealed that,despite the electronic effect of the substituents shifting the energy level of molecular orbital,the quantum interference effect vanished the influence of electronic effect on the conductance and eventually leaded to the conductance freeze.

    Quantum interference effect (QIE) is so important for charge transport at molecular scale that understanding the structural factor to manipulate QIE is of fundamental importance to the design of molecular devices [1–4].Although theσ-bond based QIE has been discovered [4],the relevant investigations on aromatic systems are still conducted vigorously,which limit the current QIE investigation to organic molecules.Metal-organic complex,which is a potential material for molecular device as important as the organic structures [5–7],in which the metal center (e.g.,Ru and Pt)participates in the conjugation system through dπ–pπconjugation and influences the energy levels of whole complex [5–7],offers a new candidate for understanding the QIE in nanoscale structures.Especially,the platinum complexes exhibit unique features by the Pt(II) taking part in the conjugation system with a restrained ratio [8].However,to our knowledge,the experimental investigation of quantum effect in metal-organic complexes has been rare conducted.

    ‘Magic ratio rule’(MRR) is a recent developed method to theoretically explain the QIE in aromatic systems [9–11].Compared with traditional graphic methods [12,13],MRR not only provides a quantitative ratio [10,14,15]to compare the conductance of corresponding molecules,but also provides the influence of electronic effect of substituents (called ‘pendant’group) on the interferometer group to the QIE on conductive backbone [14,15],from which the influence of electronic effect on the conductance could be enhanced or vanished by QIE.This implies a chance to investigate the QIE in metal-organic molecular devices by introducing electrondonating and electron-withdrawing substituents on the conductive backbone,of which the conductance is modulated by the combination of electronic effect and QIE.

    Here we report the design of three platinum(II) complexes(1,1-NH and 1-NO,Fig.1) with Pt(II) center bonded to 4-(methylthiol)phenylethynyl as the conductive backbone.Electrondonating-NH2(1-NH) or electron-withdrawing-NO2(1-NO) was introduced to act as the ‘pendant’group interacting with QIE [14].The single-molecule conductance was measured by scanning tunneling microscope break junction (STM-BJ) technique [16–20]and demonstrated a conductance freeze in all three complexes.Theoretical study revealed that the influence of electronic effect,which was introduced by ‘pendant’group,was validated by the varied energy level of molecular orbital.However,the QIE analysis according to the description of MRR confirmed the vanishing of the influence of electronic effect on conductance,eventually leading to the conductance freeze.

    Fig.1.Molecular structures of complexes 1,1-NH and 1-NO,of which the singlemolecular conductance was measured by STM-BJ technique.

    Fig.2.Conductance histogram for complexes 1,1-NH and 1-NO constructed from 3756,2185 and 2235 conductance-distance traces respectively.

    Platinum(II) complexes 1,1-NH and 1-NO were synthesizedviamodified procedures according to previous reports [8].The single-molecule conductance was measured by STM-BJ technique(Fig.1 and Supporting information) [16–20].Fig.2 shows the histograms of complexes 1,1-NH and 1-NO,which are compiled by 3756,2185 and 2235 conductance-distance traces,respectively.By employing multimodal simulation,two peaks are clearly demonstrated in the 1D histograms of all three complexes.For each complex,the high conductance presented by a small peak around 10?2G0(G0is the quantum conductance equaling to 77500 nS) is attributed to the junctions formed by the gold electrodes connecting to one methylthiol group and the Pt(II) center [8,21].For complex 1,the main peak centered at 10?4.4G0matches well with the reported conductance [22–24]and represents the conductivity of the whole conductive backbone (from one methylthiol to another).For complex 1-NO with electron-withdrawing nitro group on conductive backbone,the conductance is intuitively expected to be varied from that of complex 1.However,the conductance of 1-NO is surprisingly identical to that of complex 1.More unexpectedly,not only the electron-withdrawing group substituted complex 1-NO,but also the electron-donating amino group substituted complex 1-NH demonstrates the unchanged conductance as that of complex 1.The frozen conductance implies that the electronic effect of the ‘pendant’groups exerts negligible influence on the charge transport at single-molecule conductance.

    To validate the conductance and search the factor that the influence of electronic effect on conductance being vanished,the analyses of the junction length and 2D histogram were performed.

    Fig.3.2D histograms for complexes 1,1-NH and 1-NO with the inset showing the corresponding statistical junction length.

    As shown in Fig.3,the 2D histograms of the three complexes exhibit similar clouds around the conductance of 10?4.4G0.For complexes 1 and 1-NH,the clouds show flat plateaus indicating the stable formation of molecular junctions,whereas for complex 1-NO,the slightly oblique plateau implies that the steric hindrance of nitro group reduces the stability of molecular junctions.The snapback (0.5 nm) [25–27]corrected junction length of complex 1 is 1.7 nm,which matches perfectly with the optimized S-S distance of the complex.Probably caused by the steric hindrance,the statistical junction lengths of the substituted complexes 1-NH and 1-NO are slightly shorter than that of complex 1,where the snap-back(0.5 nm) corrected junction lengths are both 1.6 nm.Noticeably,according to the previous studies [26,28],the conductance would be more than one-order lower than that of complex 1 if the junctions formed through the connection of gold electrodes and the‘pendant’amino groups in complex 1-NH [28].The possibly low conductance is out of the effective detection range of our equipment,which makes it impossible to be observed in the conductance traces.Thus,the statistical junction length indicates that the three frozen conductance peaks at 10?4.4G0represent the real electron transport characteristics through the conductive backbones of complexes 1,1-NH and 1-NO,respectively.

    To get insight on the interesting conductance freeze in the structures with electron-donating and electron-withdrawing groups,theoretical simulation combining density functional theory(DFT) with the nonequilibrium Green’s function (NEGF) was employed [29–31].The transmission coefficient (T(E)) and molecular energy spectrum,which are commonly considered in the analysis of single-molecule conductance modulation,were computed in the QuantumATK program [20,22].The most striking feature of theT(E) curve is the sharp peak for molecule 1-NO at 0.36 eV.This peak probably indicates a Breit-Wigner type resonance caused by the electron-withdrawing effect of nitro group,in which the electron cloud is localized on the nitro group and the affiliated phenyl ring (Fig.S4 in Supporting information) [32].Although the peak manifesting a transmission coefficient peak with the similar height of a molecular orbital (e.g.,LUMO of molecule 1 at 1.26 eV),the resonance behavior does not support an orbital existing at this energy level.The reasons include: (1) the UV-vis spectra showing almost identical absorption peaks around 340 nm (Fig.4 inset) for all three complexes,which implies similar energy gaps between HOMO and LUMO for the three complexes;(2) the transmission peaks not only caused by the electron resonating with molecular orbital but also brought by the electron resonating with part of the structure (e.g.,Fano resonance,see Supporting information) [33].To further prove the resonance peak,aldehyde group,which also provides strongly electron-withdrawing effect,was employed as the ‘pendant’group to investigate the resonance of 1-CHO (one aldehyde group) and 1-diCHO (two aldehyde groups on each phenyl ring) by simulation (Supporting information).The simulatedT(E) plots of 1-CHO and 1-diCHO clearly demonstrate the Fano resonance near the energy level of LUMO (Fig.S3 in Supporting information).The electronic density distribution at the energy level of the resonance peak (dip) indicates the high localized clouds around the electronic-withdrawing group on one side of 1-CHO or on both sides of 1-diCHO,which shows almost the same distribution as complex 1-NO (Fig.S4).The localized distribution results in the Fano resonance in 1-CHO and 1-diCHO and a Breit-Wigner type resonance in 1-NO [32].Hence,the LUMO of 1-NO should be the orbital at the energy level of 1.16 eV.

    Fig.4.Transmission spectra for complexes 1,1-NH and 1-NO with the red dash line marking the possible EF and inset showing the UV-vis absorption spectrum.

    The Fermi energy (EF) of the gold electrode,which locates in the HOMO-LUMO gap,unfortunately,fails to be accurately predicted by DFT method [32].To this end,some methods have been employed to correct theEF[34],among which fitting theT(E) according to the experimental result is the most convenient way [8,14,35,36].Thus,according to the measured conductance,theEFhere should be corrected to the energy about 0.92 eV,where theT(E) of all of the three complexes including 1,1-NH and 1-NO converge to an identical value,indicating the equivalent conductance as measured by experiment.

    As shown in Fig.4,for complex 1 (green line),the peaks at-1.84,-1.74,1.26 and 1.42 eV indicate the orbital energy levels of HOMO-1,HOMO,LUMO and LUMO+1,respectively.Owing to electron-donating effect of the amino group,both HOMO and LUMO in complex 1-NH (blue line) shift to higher energy levels relative to those of complex 1.Opposite to 1-NH,the HOMO and LUMO for complex 1-NO (purple line) with electron-withdrawing nitro group,move to lower energy levels relative to those of molecule 1.The energy level shift of complexes 1-NH and 1-NO confirms the electronic effects of amino and nitro groups on the conductive backbones.According to the above correctedEF,all the three molecules exhibit LUMO dominated charge transport,of which the conductance should theoretically increase with the decrease of LUMO energy or decrease with the increase of LUMO energy.Thus,the conductance freeze of the three complexes implies that the energy effect of molecular orbital contributes little to the conductance.

    Finally,we turn to the effect of quantum interference in this conjugation system.Since the phenyl ring being a well-known interferometer,by which the destructive quantum interference and constructive quantum interference are characterized in metaconnected structures and para-/ortho-connected structures [1],the‘pendant’group substituted phenyl group of phenylethynyl ligand is considered the interferometer to analysis the MRR [14].On the phenyl group,the combined constructive/destructive QIE of the three sites connecting ethynyl group,methylthiol group and ‘pendant’group determines the finally resultant conductance.As the MRR description [14],amino (1-NH) or nitro (1-NO) group plays the role of the ‘pendant’group that changes theπ-orbital energy of the connecting site with the electronic effect by the quantitative parameter ofε.The expression of Green’s function (GF),which determines the transmission coefficient and conductance,is simplified as Eq.1 when the energy of transporting electron equals toEF:

    Whereiandjare the sites on phenyl ring connecting ethynyl and methylthiol,kis the site connecting the ‘pendant’group,Gij(0)is the GF of the molecule in the presence of ‘pendant’group,andgij(0) is the GF of the molecule without ‘pendant’group.Theg(0)is proportional to the magic number Mij.The magic number (M)equals to 0 when the two sites are the same or in meta-position to each other.Since ethynyl and ‘pendant’group are mutually located at the meta-position of phenyl ring,thegik(0) is zero for complexes 1-NH and 1-NO,respectively,which leads to the GF with the ‘pendant’group (1-NH and 1-NO) equaling to that without the‘pendant’group (1).This indicates that,for complexes 1-NH and 1-NO,the electronic effect of the amino and nitro group is vanished by the QIE and eventually results in the conductance freeze in the three complexes.

    In conclusion,three conductive Pt(II) complexes with the same conductive backbones but different ‘pendant’substituents at phenyl rings were elaborately designed.The single-molecule conductance measured by STM-BJ technique shows an interesting conductance freeze at 10?4.4G0under the varied electronic effect of ‘pendant’group.Although the theoretical study confirms the distinct influence of electronic effect on molecular orbital energy level,the QIE described by MRR eliminates the influence of the electronic effect and results in the conductance freeze.This study not only confirms the metal-organic complex to be a functioning structural base for the QIE described by MRR,but also provides a structural awareness for modulating the conductance of molecular devices.

    Declaration of competing interest

    The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

    Acknowledgments

    We are grateful for financial support from the National Natural Science Foundation of China (No.92061117),the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB20000000) and Fujian Science &Technology Innovation Laboratory for Optoelectronic Information of China (No.2021ZR129).

    Supplementary materials

    Supplementary material associated with this article can be found,in the online version,at doi:10.1016/j.cclet.2021.10.092.

    一二三四中文在线观看免费高清| 亚洲av二区三区四区| 国产亚洲一区二区精品| 午夜免费激情av| 久久综合国产亚洲精品| 精品久久国产蜜桃| 99热网站在线观看| 国产精品福利在线免费观看| 我的老师免费观看完整版| 九草在线视频观看| 久久久久免费精品人妻一区二区| 精品一区二区三卡| 中文字幕免费在线视频6| 777米奇影视久久| www.色视频.com| 日韩中字成人| 寂寞人妻少妇视频99o| 亚洲无线观看免费| 国产视频内射| 久久国内精品自在自线图片| 激情五月婷婷亚洲| 在线免费观看的www视频| 国产真实伦视频高清在线观看| 丰满乱子伦码专区| 中国国产av一级| 亚洲精品色激情综合| 亚洲伊人久久精品综合| 国产黄片美女视频| 国产大屁股一区二区在线视频| 欧美极品一区二区三区四区| 久久久久久久国产电影| 精品久久久久久成人av| 亚洲四区av| 国产av不卡久久| 在线观看一区二区三区| 国产黄片视频在线免费观看| 97超碰精品成人国产| 国产黄色视频一区二区在线观看| 日韩三级伦理在线观看| 最新中文字幕久久久久| 国产亚洲5aaaaa淫片| 国产爱豆传媒在线观看| 全区人妻精品视频| 午夜精品一区二区三区免费看| 97精品久久久久久久久久精品| 日韩欧美精品免费久久| 精品久久久久久电影网| 婷婷色综合大香蕉| 2022亚洲国产成人精品| 亚洲精品久久久久久婷婷小说| 又大又黄又爽视频免费| 深爱激情五月婷婷| 成年人午夜在线观看视频 | 午夜亚洲福利在线播放| 青青草视频在线视频观看| 好男人视频免费观看在线| 国产美女午夜福利| 婷婷色综合www| 久久久久久久久久人人人人人人| 久久精品国产亚洲av天美| 在线 av 中文字幕| 国精品久久久久久国模美| 99热网站在线观看| 亚洲精品中文字幕在线视频 | 国产男人的电影天堂91| 午夜福利在线在线| 毛片女人毛片| 最近最新中文字幕免费大全7| 亚洲国产精品成人久久小说| 国产黄片视频在线免费观看| 九色成人免费人妻av| 日韩伦理黄色片| 人妻夜夜爽99麻豆av| 岛国毛片在线播放| 日韩在线高清观看一区二区三区| 一级av片app| 熟女人妻精品中文字幕| 天天躁日日操中文字幕| 狂野欧美激情性xxxx在线观看| 亚洲一级一片aⅴ在线观看| 中文欧美无线码| 99久久九九国产精品国产免费| 国产伦精品一区二区三区四那| 亚洲三级黄色毛片| 国产 一区 欧美 日韩| 99久国产av精品| 一级黄片播放器| 欧美日韩精品成人综合77777| 久久久久精品久久久久真实原创| av免费在线看不卡| 中文字幕av在线有码专区| 亚洲欧美日韩东京热| 成人欧美大片| 欧美日韩精品成人综合77777| 人体艺术视频欧美日本| 国产精品爽爽va在线观看网站| 亚洲第一区二区三区不卡| 蜜桃久久精品国产亚洲av| 国产中年淑女户外野战色| 九草在线视频观看| 成人亚洲精品av一区二区| 国产亚洲5aaaaa淫片| 1000部很黄的大片| 色网站视频免费| 亚洲成人av在线免费| 在线播放无遮挡| 国产精品久久视频播放| 日韩大片免费观看网站| av在线蜜桃| 国产午夜福利久久久久久| 国产探花极品一区二区| 亚洲在线观看片| 午夜精品一区二区三区免费看| 在线观看人妻少妇| 久久久久久久久久久丰满| 日韩欧美国产在线观看| 国产精品久久久久久久久免| 久久精品国产亚洲网站| 欧美成人精品欧美一级黄| 欧美成人午夜免费资源| 久久人人爽人人片av| 嘟嘟电影网在线观看| 极品教师在线视频| 好男人视频免费观看在线| 18禁在线无遮挡免费观看视频| 国产伦精品一区二区三区视频9| 精品亚洲乱码少妇综合久久| 在线免费观看的www视频| 国内少妇人妻偷人精品xxx网站| 国产精品麻豆人妻色哟哟久久 | 国产精品国产三级国产专区5o| 久99久视频精品免费| 国产片特级美女逼逼视频| 国产精品熟女久久久久浪| 日日摸夜夜添夜夜爱| 免费大片18禁| 国产精品女同一区二区软件| 免费大片18禁| 嫩草影院精品99| 国产精品爽爽va在线观看网站| 我要看日韩黄色一级片| 欧美bdsm另类| 日韩不卡一区二区三区视频在线| 国产不卡一卡二| 丰满人妻一区二区三区视频av| 免费不卡的大黄色大毛片视频在线观看 | 亚洲自偷自拍三级| 18禁在线无遮挡免费观看视频| 免费看av在线观看网站| 秋霞伦理黄片| 男女边吃奶边做爰视频| 综合色丁香网| 成人二区视频| 亚洲精华国产精华液的使用体验| 天天躁夜夜躁狠狠久久av| 我的女老师完整版在线观看| 中国国产av一级| 亚洲国产精品成人久久小说| 啦啦啦韩国在线观看视频| 三级男女做爰猛烈吃奶摸视频| 神马国产精品三级电影在线观看| 国产黄a三级三级三级人| 国产亚洲av嫩草精品影院| 欧美丝袜亚洲另类| 蜜桃久久精品国产亚洲av| 18+在线观看网站| 国内精品美女久久久久久| 亚洲美女视频黄频| 一区二区三区四区激情视频| 超碰97精品在线观看| 久久这里有精品视频免费| 天堂中文最新版在线下载 | 久久这里有精品视频免费| 在线天堂最新版资源| 免费播放大片免费观看视频在线观看| 亚洲精品视频女| 成人亚洲欧美一区二区av| 久久久久免费精品人妻一区二区| 黄色一级大片看看| 国模一区二区三区四区视频| 男女边吃奶边做爰视频| av又黄又爽大尺度在线免费看| 久久久久久国产a免费观看| 我的女老师完整版在线观看| 搡老妇女老女人老熟妇| 能在线免费观看的黄片| videos熟女内射| 熟妇人妻久久中文字幕3abv| 久久热精品热| 亚洲18禁久久av| 成人国产麻豆网| 国产一区二区三区综合在线观看 | 日本一本二区三区精品| 久久久久国产网址| 日韩欧美 国产精品| 国产伦精品一区二区三区视频9| 在线观看美女被高潮喷水网站| 最近手机中文字幕大全| 九九爱精品视频在线观看| 搞女人的毛片| 在线观看av片永久免费下载| 美女黄网站色视频| 最近2019中文字幕mv第一页| 精品不卡国产一区二区三区| 18禁在线播放成人免费| 国产精品麻豆人妻色哟哟久久 | 成人亚洲精品av一区二区| 欧美三级亚洲精品| 欧美激情在线99| 日本三级黄在线观看| 人人妻人人澡人人爽人人夜夜 | 美女高潮的动态| 国产一级毛片在线| 极品少妇高潮喷水抽搐| 赤兔流量卡办理| 97超碰精品成人国产| 人妻夜夜爽99麻豆av| 国产精品女同一区二区软件| 黄色欧美视频在线观看| 在线观看一区二区三区| 国产乱来视频区| 看十八女毛片水多多多| 狂野欧美激情性xxxx在线观看| 高清毛片免费看| 午夜福利网站1000一区二区三区| 69av精品久久久久久| 国产成人精品一,二区| 婷婷色麻豆天堂久久| 大片免费播放器 马上看| 老女人水多毛片| 看十八女毛片水多多多| 成人毛片60女人毛片免费| 亚洲欧美成人综合另类久久久| 免费不卡的大黄色大毛片视频在线观看 | 五月伊人婷婷丁香| 日韩大片免费观看网站| 六月丁香七月| 99热这里只有是精品在线观看| 丝瓜视频免费看黄片| 啦啦啦韩国在线观看视频| 日韩精品青青久久久久久| 一个人观看的视频www高清免费观看| 亚洲人成网站在线播| 我的老师免费观看完整版| 国产高清有码在线观看视频| 成人一区二区视频在线观看| 深夜a级毛片| 午夜老司机福利剧场| 日韩电影二区| 国产 亚洲一区二区三区 | 五月天丁香电影| 亚洲在久久综合| 欧美精品国产亚洲| 尤物成人国产欧美一区二区三区| 亚洲成人精品中文字幕电影| 亚洲欧美中文字幕日韩二区| 老司机影院毛片| 中国国产av一级| 真实男女啪啪啪动态图| 亚洲成人中文字幕在线播放| 亚洲人与动物交配视频| 日本-黄色视频高清免费观看| 国产视频首页在线观看| 中文字幕亚洲精品专区| 免费在线观看成人毛片| 人妻少妇偷人精品九色| 三级毛片av免费| 国产视频内射| 非洲黑人性xxxx精品又粗又长| 毛片女人毛片| 校园人妻丝袜中文字幕| 国产精品久久视频播放| 亚洲欧美中文字幕日韩二区| 色视频www国产| 国产大屁股一区二区在线视频| 日韩成人伦理影院| 亚洲成色77777| 中文字幕av成人在线电影| 久久99热这里只有精品18| 一级毛片我不卡| 特级一级黄色大片| 激情五月婷婷亚洲| 成年女人在线观看亚洲视频 | 国产黄片视频在线免费观看| 联通29元200g的流量卡| 91午夜精品亚洲一区二区三区| 免费不卡的大黄色大毛片视频在线观看 | 嫩草影院入口| 国产69精品久久久久777片| 成人欧美大片| 日韩精品青青久久久久久| 18禁在线播放成人免费| 又爽又黄无遮挡网站| 人妻制服诱惑在线中文字幕| 国产伦精品一区二区三区视频9| 成人午夜高清在线视频| 极品教师在线视频| 欧美最新免费一区二区三区| 菩萨蛮人人尽说江南好唐韦庄| 性色avwww在线观看| 亚洲三级黄色毛片| 国产精品综合久久久久久久免费| 久久久精品94久久精品| 男人狂女人下面高潮的视频| 国产黄片美女视频| 国产成年人精品一区二区| 欧美xxxx性猛交bbbb| 日本熟妇午夜| 七月丁香在线播放| 性色avwww在线观看| 成人午夜精彩视频在线观看| 久久99精品国语久久久| 国产男女超爽视频在线观看| 啦啦啦韩国在线观看视频| 国产 一区 欧美 日韩| 亚洲精品久久久久久婷婷小说| 国产精品久久久久久精品电影| 亚洲欧美清纯卡通| 天堂av国产一区二区熟女人妻| av免费观看日本| 最后的刺客免费高清国语| 最近最新中文字幕大全电影3| 免费av不卡在线播放| 一级片'在线观看视频| 熟妇人妻不卡中文字幕| 男的添女的下面高潮视频| 18禁在线播放成人免费| 天堂网av新在线| av播播在线观看一区| 午夜福利视频1000在线观看| av专区在线播放| 亚洲av成人精品一二三区| 熟女人妻精品中文字幕| 伊人久久精品亚洲午夜| 亚洲国产精品sss在线观看| 久久精品久久精品一区二区三区| 亚洲在线观看片| ponron亚洲| 午夜亚洲福利在线播放| 欧美日韩亚洲高清精品| 国产一区有黄有色的免费视频 | 久久久久久久久久成人| 中文天堂在线官网| 国产 一区精品| 综合色丁香网| videos熟女内射| 只有这里有精品99| 插阴视频在线观看视频| 中文字幕久久专区| 日产精品乱码卡一卡2卡三| 男女视频在线观看网站免费| 日本黄色片子视频| 国产白丝娇喘喷水9色精品| 亚洲精品色激情综合| 熟女人妻精品中文字幕| 国产成人午夜福利电影在线观看| 亚洲av男天堂| 熟女人妻精品中文字幕| 成年版毛片免费区| 国产精品熟女久久久久浪| 国产中年淑女户外野战色| 久久久久免费精品人妻一区二区| 久久这里只有精品中国| 成人av在线播放网站| 搞女人的毛片| 国产一区亚洲一区在线观看| 3wmmmm亚洲av在线观看| 欧美成人一区二区免费高清观看| 成年女人在线观看亚洲视频 | 神马国产精品三级电影在线观看| 色播亚洲综合网| 天堂av国产一区二区熟女人妻| 97人妻精品一区二区三区麻豆| 亚洲国产最新在线播放| 80岁老熟妇乱子伦牲交| 国产男人的电影天堂91| 亚洲av不卡在线观看| 成人亚洲精品一区在线观看 | 精品一区二区三卡| 国产毛片a区久久久久| 又大又黄又爽视频免费| 欧美成人a在线观看| 日韩电影二区| 日韩三级伦理在线观看| 久久精品熟女亚洲av麻豆精品 | 国产一级毛片在线| 日韩伦理黄色片| 精品久久久久久成人av| 日日撸夜夜添| 亚洲av成人精品一区久久| 亚洲av福利一区| 国产成人精品一,二区| 亚洲av福利一区| 大又大粗又爽又黄少妇毛片口| 国产国拍精品亚洲av在线观看| 国产探花在线观看一区二区| 综合色av麻豆| 搞女人的毛片| 大片免费播放器 马上看| 在线a可以看的网站| 性色avwww在线观看| 成年女人看的毛片在线观看| 久99久视频精品免费| 亚洲精品视频女| 麻豆精品久久久久久蜜桃| 蜜臀久久99精品久久宅男| 国产69精品久久久久777片| 久久国产乱子免费精品| 国产久久久一区二区三区| 美女国产视频在线观看| 夜夜爽夜夜爽视频| 久久久久久久午夜电影| 欧美人与善性xxx| 久久97久久精品| h日本视频在线播放| 一级毛片我不卡| 日本-黄色视频高清免费观看| 国产亚洲av嫩草精品影院| 午夜福利网站1000一区二区三区| 少妇熟女欧美另类| 亚洲精品成人久久久久久| 熟妇人妻不卡中文字幕| 亚州av有码| 男女那种视频在线观看| 在线观看一区二区三区| 非洲黑人性xxxx精品又粗又长| 天天一区二区日本电影三级| 日日撸夜夜添| 建设人人有责人人尽责人人享有的 | 免费观看av网站的网址| 亚洲aⅴ乱码一区二区在线播放| 80岁老熟妇乱子伦牲交| 日韩大片免费观看网站| 内地一区二区视频在线| 91aial.com中文字幕在线观看| 久久久久网色| 99视频精品全部免费 在线| 激情 狠狠 欧美| 大又大粗又爽又黄少妇毛片口| 久久99热这里只有精品18| 久久草成人影院| 久久精品人妻少妇| 18禁在线无遮挡免费观看视频| 国产探花极品一区二区| 日韩成人av中文字幕在线观看| 成人高潮视频无遮挡免费网站| 国产免费视频播放在线视频 | 春色校园在线视频观看| 日韩欧美 国产精品| 午夜爱爱视频在线播放| 人人妻人人澡欧美一区二区| 18禁动态无遮挡网站| 免费av毛片视频| 日本一本二区三区精品| or卡值多少钱| 亚洲色图av天堂| 一级毛片我不卡| 国产高潮美女av| 非洲黑人性xxxx精品又粗又长| 亚洲国产精品sss在线观看| 高清毛片免费看| av在线观看视频网站免费| 国产极品天堂在线| 色播亚洲综合网| 十八禁网站网址无遮挡 | 日本wwww免费看| 午夜福利成人在线免费观看| 亚洲熟女精品中文字幕| 久久久久网色| 精品国产一区二区三区久久久樱花 | 亚洲aⅴ乱码一区二区在线播放| 亚洲图色成人| 精品久久久噜噜| 99久久中文字幕三级久久日本| av线在线观看网站| 婷婷色麻豆天堂久久| 国产视频内射| 国产午夜精品久久久久久一区二区三区| 亚洲精品成人av观看孕妇| av网站免费在线观看视频 | 国产片特级美女逼逼视频| 九九在线视频观看精品| 亚洲aⅴ乱码一区二区在线播放| 亚洲国产日韩欧美精品在线观看| 少妇的逼好多水| 国产在视频线在精品| 国产精品久久久久久精品电影| 别揉我奶头 嗯啊视频| 热99在线观看视频| 亚洲av不卡在线观看| 亚洲欧美日韩无卡精品| 久久人人爽人人片av| 中文字幕av成人在线电影| av国产久精品久网站免费入址| 亚洲国产高清在线一区二区三| 非洲黑人性xxxx精品又粗又长| 男女下面进入的视频免费午夜| 免费黄频网站在线观看国产| 亚洲精品国产成人久久av| 国产成人精品福利久久| 精品一区二区三区视频在线| av免费观看日本| 国产一区有黄有色的免费视频 | 精品久久久噜噜| 97在线视频观看| 小蜜桃在线观看免费完整版高清| 久久99热这里只有精品18| 高清日韩中文字幕在线| 啦啦啦啦在线视频资源| 自拍偷自拍亚洲精品老妇| 久久久久网色| 最近中文字幕2019免费版| 亚洲欧美日韩卡通动漫| 欧美潮喷喷水| 国产精品久久视频播放| 熟女人妻精品中文字幕| 你懂的网址亚洲精品在线观看| 18禁裸乳无遮挡免费网站照片| 亚洲,欧美,日韩| 日韩强制内射视频| 精品久久久久久久人妻蜜臀av| 国产成年人精品一区二区| 亚洲图色成人| 欧美日韩精品成人综合77777| 中文字幕亚洲精品专区| 又大又黄又爽视频免费| 欧美成人午夜免费资源| 精品久久久久久久久亚洲| 晚上一个人看的免费电影| 精品久久久久久电影网| 99久久人妻综合| 色吧在线观看| 国产成人精品一,二区| 中文精品一卡2卡3卡4更新| 成人一区二区视频在线观看| 国产男人的电影天堂91| 日韩一区二区视频免费看| av一本久久久久| 看黄色毛片网站| a级毛片免费高清观看在线播放| 天堂av国产一区二区熟女人妻| 综合色av麻豆| 日日摸夜夜添夜夜添av毛片| 亚洲av一区综合| 色综合色国产| 日日干狠狠操夜夜爽| 亚洲成人av在线免费| 99热全是精品| 国产 亚洲一区二区三区 | 亚洲美女搞黄在线观看| av一本久久久久| 成人亚洲欧美一区二区av| 99热全是精品| 国产精品国产三级国产av玫瑰| 国产伦在线观看视频一区| 毛片女人毛片| 精品久久久久久久久亚洲| 欧美潮喷喷水| 天天躁日日操中文字幕| 2022亚洲国产成人精品| 精品亚洲乱码少妇综合久久| 成人漫画全彩无遮挡| 免费观看在线日韩| 欧美 日韩 精品 国产| 亚洲熟妇中文字幕五十中出| 国产成人精品福利久久| 亚洲人与动物交配视频| 久久久久久伊人网av| 麻豆成人av视频| 精品欧美国产一区二区三| 国产不卡一卡二| 国产在线男女| 一区二区三区免费毛片| 国产极品天堂在线| 日本一本二区三区精品| av在线播放精品| 久久热精品热| 日日啪夜夜爽| 日本免费a在线| 国产免费福利视频在线观看| 亚洲精品国产av蜜桃| 国产精品三级大全| 三级经典国产精品| 国产在视频线精品| 22中文网久久字幕| 精品人妻熟女av久视频| 中文字幕av成人在线电影| 国产黄色视频一区二区在线观看| 蜜臀久久99精品久久宅男| 国产视频内射| 国产 一区精品| 丝瓜视频免费看黄片| 免费电影在线观看免费观看| 国国产精品蜜臀av免费| 国产伦在线观看视频一区| 色播亚洲综合网| 你懂的网址亚洲精品在线观看| 乱系列少妇在线播放| 中文欧美无线码| 欧美成人午夜免费资源| 亚洲18禁久久av| 国产精品不卡视频一区二区| 日韩av在线大香蕉| 国产午夜福利久久久久久| 最近2019中文字幕mv第一页| 91av网一区二区| 久久久久久久久久久丰满| 国产黄a三级三级三级人| 久久久久久久久久成人| 18禁在线无遮挡免费观看视频| 三级国产精品欧美在线观看| 国产精品一二三区在线看| 最新中文字幕久久久久| 午夜精品一区二区三区免费看| 最近视频中文字幕2019在线8|