• <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 ?

    Optically probing molecular shuttling motion of [2]rotaxane by a conformation-adaptive fluorophore

    2022-12-07 08:26:58ChengyunYuXiodongWngCiXinZhoShunYngJinGnZhuoWngZhnqiCoHuiQu
    Chinese Chemical Letters 2022年11期

    Chengyun Yu, Xiodong Wng, Ci-Xin Zho, Shun Yng, Jin Gn, Zhuo Wng,Zhnqi Co, D-Hui Qu,?

    a Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China

    bShanghai Gantian Optical Material Co., Ltd., Shanghai 201512, China

    c College of Science, Henan Agricultural University, Zhengzhou 450002, China

    Keywords:[2]Rotaxane Optically probe Mechanical shuttling Molecular conformations Conformation-adaptive macrocycle

    ABSTRACT A bistable [2]rotaxane with a conformation-adaptive macrocycle bearing a 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine (DPAC) unit was synthesized, which could be utilized to optical probe the molecular shuttling motion of the functionalized rotaxane system.The UV–vis, 1H NMR and PL spectroscopic data clearly demonstrated that the DPAC ring was interlocked onto the thread and the fluorescence intensity of the DPAC unit in the macrocycle was effectively regulated by the location change of the macrocycle along the thread under acid/base stimulation, which was attributed to the modulation of the intramolecular photo-induced electron transfer between the DPAC unit and the methyltriazole (MTA)unit.This bistable rotaxane system containing a conformation-adaptive fluorophore unit in the macrocycle moiety opens an alternative way to design functional bistable mechanically interlocked molecules.

    Since the first introduction of supramolecular chemistry [1,2],macrocyclic molecules [3] as an important branch have gained particular attention and developed numerous potential applications in various fields.Macrocycles are often structured with a special ring motif, such as crown ether [4], in which these cyclic motifs could be efficiently interacted with guest molecules.The crown ether ring embellished with fluorophores has been introduced into mechanical interlocking molecules (MIMs) [5] to construct smart fluorescence systems, which have been widely adopted in photoelectric switches [6,7], molecular recognition [8], fluorescent probes[9,10], drug delivery [11] and smart materials [12–15].A typical MIMs system consists of a macrocyclic host structure, such as a rotaxane, which a rod-shaped guest axle and two big blocking groups to prevent the separation of the ring components.Among the many macrocycle-based MIMs, one of the most common types is the rotaxane that could produce luminescence upon different stimulus (acid/base [16,17], ion binding [18,19], light [20,21] or oxidation state change [22]).The fluorescent signal was proven to be an efficient approach to monitor the ring’s mechanical movement,taking advantages of the F?rster resonance energy transfer (FRET),photo-induced electron transfer (PET) mechanism.Meanwhile, the mechanical shuttling motion of the host molecule can also be effectively monitored and even regulated based on its fluorescence performance [23].Nevertheless, more efforts are necessary for developing new fluorescent macrocyclic systems, in order to widen the range of the potential application for current supramolecular macrocycles.

    A single-molecule conformation-adaptive fluorophore based on 9,14-dihydrodibenzo[a,c]phenazine derivatives (DPAC) [24] has been reported, which has uniquely large Stokes shift and multiple fluorescence properties and been used for fluorescent probes [25],bioimaging [26].Recently, Tianet al.realized geometric changes and inversions from bending to plane in the exciting process, using chemical approaches, such as intramolecular cyclization [27] and substituent effects [28], both which can precisely tune the fluorescence properties for the dihydrophenazine molecules.Apart from these, we also reported a [2]catenane consisting of a DPAC-based fluorescent macrocycle [29], in which the conformation-adaptive emission of DPAC ring was precisely controlled in the interlocked environment.Thus, it is possible to apply the single fluorophore in fluorescent switches to regulate the multi-color or intensity emission.Therefore, this controllable fluorescence property of the DPAC-ring would be useful for developing MIMs’applications.

    Herein, we report a unique DPAC-crown ether ring-modified[2]rotaxane system, a dedicatedly designed optical probe that could be precisely regulated by the unique dynamic adaptive mechanism of the fluorescence unit.As shown in Fig.1, the target [2]rotaxane 2-H?2PF6contained a DPAC-functional crown ether macrocyclic component and two large blocking groups at both ends to prevent the departure of cyclic components.There were two structured blocking units on the rod-shaped component, that was dibenzylammonium (DBA) andN-methyltriazolium (MTA), as the binding sites of the ring.The experimental results suggested that the DPAC ring could recognize the binding sites based on the different binding affinity of the stations towards the ring upon stimuli-response.The conformation freedom of the DPAC ring varied with the recognition sites (i.e., at different recognition sites, diverse sized guest molecules could bind to the host ring), resulting in the change of the fluorescence (wavelength and intensity).This supramolecular host macrocyclic structure with vibrationintroduced emission characteristics can optically monitor different guest molecules through the conformation freedom of the vibration motion of the DPAC’s aromatic backbone.The phenomena provide a good strategy for developing advanced supramolecular system and designing functional bistable mechanically interlocked molecules.

    Fig.1 .The synthesis routes of the [2]rotaxanes.Reaction conditions: (i) Cu(CH3CN)4PF6 (1.1 equiv.), anhydrous dichloromethane, 25°C for 4 h; (ii) CH3I (6.0 equiv.), NH4PF6,methanol, 40°C for 36 h; (iii) Et3N (5.0 equiv.), (Boc)2O (5.0 equiv.), dichloromethane, Ar, 25°C for 12 h.

    To synthesize the target [2]rotaxane 2-H?2PF6, we started with the one-step synthesis of the [2]rotaxane 1-H?PF6from the known compounds (Fig.1, Supporting information for details).The compound [2]rotaxane 2-H?2PF6was obtained from the methylation of the triazole unit of [2]rotaxane 1-H?PF6.This was confirmed by the characteristic chemical shifts of the methyl hydrogen and Hg(Fig.1) on methyltriazole (MTA) according to the1H NMR.Meantime, a significant displacement of the characteristic protons H9–13on the ring and Ha, Hbon the axle was observed.Two-dimensional1H NOE signals were found between NH2+and hydrogens (H11,H12, H13) on the DPAC ring (Figs.S10-S12 in Supporting information), which confirmed that: 1) the correlation between the ring and axle; 2) the DPAC-ring well fit at the dibenzylammonium (DBA) recognition site.Additionally, the high-resolution ESIMS spectrum of [2]rotaxane 2-H?2PF6showed an intense peak atm/z1317.5280, which was assigned to the [2]rotaxane 2-H?2PF6after losing one of the PF6counterions.

    The DBA salt in [2]rotaxane 2-H?2PF6was deprotonated and protected with di–tert–butyl dicarbonate ((Boc)2O), then a reference [2]rotaxane 4-H?PF6was therefore obtained.In COZY and NOESY NMR spectra (Figs.S16-S18 in Supporting information),there were the appearance of new cross peaks (representing the three characteristic protons H6and Hl, Hf).It proved that the DPAC-ring was located on MTA station away from the Bocprotected DBA recognition site, and the signal of characteristic hydrogen Hfupshifted due to the shielding effect of the crown ether.By using a similar synthesis method of [2]rotaxane 4-H?PF6,another reference compound [2]rotaxane 3-H was obtained from[2]rotaxane 1-H?PF6.The structures of these compounds were further confirmed by mass spectrometry (Figs.S28-S31 in Supporting information).

    Then the intrinsic optical properties of the [2]rotaxane was particularly characterized (Fig.2).A absorption band with a maximum wavelength (λabs) at 345 nm was observed for [2]rotaxane 2-H?2PF6.Comparing with the free DPAC ring [29], the maximum absorption of [2]rotaxane 2-H?2PF6exhibited a faintly blueshifted, which was similar with that of [2]rotaxane 1-H?PF6in dichloromethane solution (Fig.2a).The slight difference between the free DPAC ring and [2]rotaxane 2-H?2PF6mainly resulted from the deplanarization of the aromatic backbone and the enhancement of DPAC ring conformation tension after binding the DBA site in [2]rotaxane 2-H?2PF6.Similar phenomenon in which the macrocycles with distinctly shifted optical properties before and after the host-guest recognition have been reported before [30].Interestingly, the fluorescence quantum yields of the two [2]rotaxanes were greatly different and the emission intensity of [2]rotaxane 2-H?2PF6was 5% less than that of [2]rotaxane 1-H?PF6.It was believed that the cation dipole interaction between the crown ether ring and the positive charge of MTA resulted in the decrease of the fluorescence quantum yield [31].Meanwhile, it was found that the DPAC ring could be a good optical monitor when the subtle chemical environment was changed.In blank experiments, [2]rotaxane 3-H (λabs=362 nm) showed a larger red-shifted absorption because the conformation of the DPAC ring was free with no recognition sites.And the absorption and emission peak of [2]rotaxane 4-H?PF6was consistent with the [2]rotaxane 2-H?2PF6, the latter was comparatively larger in the degree of blue-shift.Since the binding ability of crown ether and MTA was weaker than that of the crown ether and DBA group, the aromatic skeleton planarization of the DPAC ring was relatively smaller when the ring was constrained by surrounded glycol chains.In addition, the luminescence almost quenched owing to the intramolecular photo-induced electron transfer effect (PET) between the electron-positive DPAC chromophore and electron-deficient MTA molecule, indicating that the DPAC ring can be used as a conformational adaptive fluorophore optically detecting the molecular shuttle motion of [2]rotaxane.

    Fig.2 .The photophysical properties of [2]rotaxanes.UV–vis absorption spectra(a) and fluorescence spectra (b) of target [2]rotaxanes in dichloromethane (pathlength=10 mm, c=40 μmol/L, λex=350 nm).

    Subsequently, the reversible shuttling movement of target [2]rotaxane 2-H?2PF6and the changes of photophysical properties of the DPAC-ring were investigated by1H NMR, UV–vis and PL spectroscopy under acid-base stimuli.Upon the addition of 1.2 equiv.1,8-diazabicyclo[5.4.0]undec–7-ene (DBU) to neutralize the DBA group of [2]rotaxane 2-H?2PF6in dichloromethane, the characteristic hydrogens for Hg, Hl, Hf, Hmwere shifted upfield significantly(Δδg=0.46, 0.4 ppm; Δδl=0.61, 0.59 ppm; Δδf=0.54, 0.98 ppm;Δδm=0.85 ppm) (Figs.3a and b), implying that the shielding effect of the DPAC ring was forced to slip to the MTA station away from the DBA recognition site.According to the literature upfield shifts within different degrees and the disappearance of the NH2+signal in 2D NMR spectroscopy (Figs.S12 in Supporting informaiton)suggested that the formation of hydrogen bonds between the MTA station and the macrocycle.Furthermore, the deprotonated [2]rotaxane 2?PF6was again mixed with 1.2 equiv.of trifluoroacetate(TFA), the correlation of the [2]rotaxane 2-H?2PF6and with the DPAC-ring at DBA site was reformed again, leading to the chemical peak returned to its initial position (Fig.3c).Therefore, the molecular shuttling motion of [2]rotaxane 2-H?2PF6can be easily realized between the DBA and MTA recognition sites upon acid or base conditions.

    Fig.3 .(a) Partial 1H NMR (400 MHz, CD2Cl2, 298 K) spectra of [2]rotaxane 2-H?2PF6, (b) [2]rotaxane 2-H?2PF6 after adding 1.2 equiv.DBU, (c) [2]rotaxane 2-H?2PF6+1.2 equiv.DBU after adding 1.2 equiv.TFA.

    Then, the changes of the optical properties of the shuttling motion [2]rotaxane 2-H?2PF6was further investigated.Under base treatment, the absorption of the deprotonated [2]rotaxane 2?PF6showed a slight red-shift and a maximum peak (λabs=351 nm)(Fig.4).Interestingly, a fluorescence quenching effect accompanied with a weak blue-shift was observed.The weaker hydrogen bonds between crown ether and MTA released the conformation tension of the DPAC, the DPAC ring was prone to planarization on the excited state, resulting in the fluorescence emission blueshift.Since the MTA structure was an electron-deficient acceptor and easily to generate cation-dipole interaction, when the ring located at MTA recognition site, strong intramolecular PET effect occurred, which caused the fluorescence quenching.The similar phenomenon was also observed in the reference compound [2]rotaxane 4-H?PF6(λabs/λem=350/421 nm in dichloromethane), which further confirm us demonstration, that the DPAC ring had slipped at toward the triazole MTA from the DBA recognition site, and the fluorescence quenching was closely related to the triazole MTA group.After addition of TFA into the deprotonated [2]rotaxane 2?PF6, the NH group of DBA site reprotonated and the macrocyclic returned to its original location.In the current state, the DPAC ring adopted a deplanarized conformation due to strong hydrogen bonds and the intramolecular PET phenomenon disappears, resulting in the reversion of the absorption and fluorescence.These obvious fluorescence changes indicated that the DPAC-functionalized ring could be used as an optical probe to monitor the molecule reversibly shuttle among the DBA and MTA recognition sites.

    Fig.4 .The photophysical characteristics of [2]rotaxane 2-H?2PF6 driven by acidbase in dichloromethane.UV–vis absorption spectra (a) and fluorescence spectra(c) of [2]rotaxane 2-H?2PF6 titrated with 1.2 equiv.DBU.UV–vis absorption spectra(b) and fluorescence spectra (d) of [2]rotaxane 2-H?2PF6+1.2 equiv.DBU and then adding 1.2 equiv.TFA (pathlength=10 mm, c=80 μmol/L, λex=350 nm).

    Furthermore, in order to verify our hypothesis, addition excessive base or acid to the dichloromethane solution of [2]rotaxane 4-H?PF6, it was found that there was no change of the UV–vis absorption, fluorescence emission or1H NMR (Figs.S3 and S6 in Supporting information).Because the DPAC ring has been recognized on the MTA site and the conformation was fixed.And the fluorescence emission of [2]rotaxane 4-H?PF6was always quenched,which was consistent with the phenomenon of [2]rotaxane 2-H?2PF6driven by the base.For [2]rotaxane 3-H, after adding 1.2 equiv.TFA, the absorption of [2]rotaxane 3 exhibited a blue-shift,but its fluorescence intensity was quenched (Fig.S2 in Supporting information).This may be attributed to the intramolecular PET effect between electron-rich donor DPAC chromophore and the formation of electron-deficient triazole groups in an acidic condition.If an equivalent amount of DBU was added in slowly, its absorption and emission spectra (wavelength and intensity) returned to its original state.

    Therefore, except for [2]rotaxane 4-H?PF6, [2]rotaxane 2-H?2PF6, [2]rotaxane 1-H?PF6and [2]rotaxane 3-H all achieved reversible fluorescence wavelength or intensity switching upon acid or base stimulation.The key feature of the [2]rotaxane 2-H?2PF6was that the conformation-adaptive macrocycle leading the functionalized rotaxane to undergo optically probe molecular shuttling motions by addition acid or base.

    In summary, we have successfully synthesized [2]rotaxane 2-H?2PF6and three reference compounds ([2]rotaxane 1-H?PF6,[2]rotaxane 3-H, [2]rotaxane 4-H?PF6) based on conformationadaptive macrocycle DPAC.The DPAC ring was proved to shuttle between the recognition sites with different binding abilities, leading to the discrepancy of conformational distortion and fluorescence properties of the DPAC molecule.The results were found that the intrinsic luminescence of the DPAC molecule was restricted by the unique dynamic adaptive mechanism and the fluorophore quenching of DPAC was closely related to the intramolecular PET effect.Therefore, the DPAC chromophore can be used as a signal output to monitor the molecular shuttling motion and a new main fluorescence macrocycle on MIMs.In addition, [2]rotaxane 1-H?PF6, [2]rotaxane 2-H?2PF6can be used as fluorescent molecular probes with excellent performance under acid-base conditions,which provides a new inspiration for the simple design of a multimode stimulating fluorescent output system.

    Declaration of competing interest

    The authors declare no competing financial interest.

    Acknowledgments

    This work was supported by the National Natural Science Foundation of China (Nos.22025503, 21790361 and 21871084),Shanghai Municipal Science and Technology Major Project (No.2018SHZDZX03), the Fundamental Research Funds for the Central Universities, the Program of Introducing Talents of Discipline to Universities (No.B16017), the Shanghai Science and Technology Committee (No.17520750100).This project has received funding from China Postdoctoral Science Foundation funded project (No.J100–5R-20130).We thank the Research Center of Analysis and Test of East China University of Science and Technology for help on the material characterization.

    Supplementary materials

    Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2022.03.004.

    一区二区日韩欧美中文字幕| 中文字幕制服av| 99精品欧美一区二区三区四区| 97人妻天天添夜夜摸| 日日摸夜夜添夜夜添小说| 精品第一国产精品| 18禁裸乳无遮挡动漫免费视频| 99热国产这里只有精品6| 又大又爽又粗| av欧美777| 啦啦啦免费观看视频1| 国产成人精品久久二区二区免费| 女人爽到高潮嗷嗷叫在线视频| 一区在线观看完整版| 悠悠久久av| 91九色精品人成在线观看| 亚洲精品国产色婷婷电影| 99国产综合亚洲精品| 天天躁狠狠躁夜夜躁狠狠躁| 国产精品国产高清国产av | 亚洲av成人一区二区三| 18禁黄网站禁片午夜丰满| 欧美乱码精品一区二区三区| 性少妇av在线| 欧美激情高清一区二区三区| kizo精华| 国产精品99久久99久久久不卡| 真人做人爱边吃奶动态| 免费久久久久久久精品成人欧美视频| aaaaa片日本免费| 国产福利在线免费观看视频| 深夜精品福利| 久久国产精品男人的天堂亚洲| 精品福利观看| 成人18禁高潮啪啪吃奶动态图| 国产精品久久久久久人妻精品电影 | 亚洲色图av天堂| 菩萨蛮人人尽说江南好唐韦庄| 亚洲精品一二三| 飞空精品影院首页| 一级毛片精品| 国产不卡av网站在线观看| 国产无遮挡羞羞视频在线观看| 咕卡用的链子| av网站在线播放免费| 男女免费视频国产| 日本精品一区二区三区蜜桃| 亚洲国产毛片av蜜桃av| 欧美激情久久久久久爽电影 | 在线永久观看黄色视频| 不卡一级毛片| 美国免费a级毛片| 91老司机精品| 成年女人毛片免费观看观看9 | 亚洲天堂av无毛| 国产精品一区二区在线观看99| 国产精品影院久久| 水蜜桃什么品种好| 色播在线永久视频| 成人18禁高潮啪啪吃奶动态图| 菩萨蛮人人尽说江南好唐韦庄| 香蕉国产在线看| 亚洲国产欧美一区二区综合| 欧美日韩中文字幕国产精品一区二区三区 | 国产欧美日韩一区二区三| 不卡av一区二区三区| 欧美黄色片欧美黄色片| videos熟女内射| 成人影院久久| 人人妻,人人澡人人爽秒播| 欧美中文综合在线视频| 美女国产高潮福利片在线看| 国产精品秋霞免费鲁丝片| 亚洲午夜理论影院| 亚洲精品乱久久久久久| 99香蕉大伊视频| 中文字幕另类日韩欧美亚洲嫩草| 免费在线观看视频国产中文字幕亚洲| 怎么达到女性高潮| 国产亚洲欧美精品永久| 国产熟女午夜一区二区三区| 国产欧美日韩精品亚洲av| 国产真人三级小视频在线观看| 亚洲国产成人一精品久久久| 热99国产精品久久久久久7| 男女高潮啪啪啪动态图| 成人国产av品久久久| 午夜福利乱码中文字幕| 少妇粗大呻吟视频| 国产视频一区二区在线看| 日韩免费高清中文字幕av| svipshipincom国产片| 午夜精品久久久久久毛片777| 日韩人妻精品一区2区三区| 亚洲av第一区精品v没综合| 少妇裸体淫交视频免费看高清 | 欧美日韩亚洲综合一区二区三区_| 久久ye,这里只有精品| 日韩大码丰满熟妇| 中国美女看黄片| 中国美女看黄片| 亚洲七黄色美女视频| 少妇裸体淫交视频免费看高清 | av天堂在线播放| 另类精品久久| 高清毛片免费观看视频网站 | 午夜激情久久久久久久| 最黄视频免费看| 少妇精品久久久久久久| 欧美亚洲日本最大视频资源| 亚洲伊人色综图| 另类亚洲欧美激情| 免费观看人在逋| 国产成人av教育| 黑人欧美特级aaaaaa片| 咕卡用的链子| 国产视频一区二区在线看| 婷婷丁香在线五月| 天堂动漫精品| 超色免费av| 亚洲成国产人片在线观看| 国产亚洲欧美精品永久| 50天的宝宝边吃奶边哭怎么回事| 国产精品一区二区精品视频观看| 大型黄色视频在线免费观看| av天堂在线播放| 另类亚洲欧美激情| 免费高清在线观看日韩| 母亲3免费完整高清在线观看| 免费在线观看黄色视频的| 2018国产大陆天天弄谢| 一级毛片精品| 激情在线观看视频在线高清 | 亚洲色图av天堂| 伊人久久大香线蕉亚洲五| 欧美av亚洲av综合av国产av| 精品人妻在线不人妻| 美女高潮喷水抽搐中文字幕| 90打野战视频偷拍视频| 男人操女人黄网站| 精品欧美一区二区三区在线| 免费久久久久久久精品成人欧美视频| 人人妻人人澡人人爽人人夜夜| 女同久久另类99精品国产91| 丁香六月欧美| 久久精品人人爽人人爽视色| 国产精品.久久久| 国产在线观看jvid| 在线观看免费高清a一片| 美国免费a级毛片| 女性被躁到高潮视频| www.自偷自拍.com| 考比视频在线观看| 大陆偷拍与自拍| 最黄视频免费看| 一级片'在线观看视频| 午夜91福利影院| 亚洲精品国产区一区二| 日韩视频在线欧美| 精品国产一区二区三区四区第35| 一个人免费在线观看的高清视频| 后天国语完整版免费观看| 2018国产大陆天天弄谢| 丝袜美足系列| 欧美日韩黄片免| www.自偷自拍.com| 他把我摸到了高潮在线观看 | 18禁黄网站禁片午夜丰满| 热99re8久久精品国产| 可以免费在线观看a视频的电影网站| 国产激情久久老熟女| 午夜精品久久久久久毛片777| 成人黄色视频免费在线看| 久久精品91无色码中文字幕| 黄色片一级片一级黄色片| 午夜久久久在线观看| 精品国产乱子伦一区二区三区| 国产老妇伦熟女老妇高清| 丁香六月欧美| 啦啦啦 在线观看视频| 一区二区三区国产精品乱码| 可以免费在线观看a视频的电影网站| 日韩人妻精品一区2区三区| 国产在线免费精品| 9热在线视频观看99| 久久久久久人人人人人| 免费看a级黄色片| 考比视频在线观看| 90打野战视频偷拍视频| 黄色视频,在线免费观看| 中文字幕制服av| 99九九在线精品视频| 亚洲精品在线美女| 丝袜喷水一区| 大型黄色视频在线免费观看| 国产精品久久久久久人妻精品电影 | 国产欧美日韩一区二区三区在线| 热99re8久久精品国产| av线在线观看网站| 国产真人三级小视频在线观看| 成年动漫av网址| 一进一出抽搐动态| 黄色片一级片一级黄色片| 午夜久久久在线观看| 成人永久免费在线观看视频 | 亚洲av日韩精品久久久久久密| 欧美乱妇无乱码| 亚洲第一欧美日韩一区二区三区 | 亚洲专区字幕在线| 久久久久久人人人人人| 天堂动漫精品| 老司机影院毛片| 国产av又大| 老司机午夜福利在线观看视频 | 男女无遮挡免费网站观看| 亚洲成av片中文字幕在线观看| 狠狠婷婷综合久久久久久88av| 日韩大码丰满熟妇| 搡老乐熟女国产| 欧美精品亚洲一区二区| 亚洲全国av大片| 精品少妇黑人巨大在线播放| kizo精华| 国产精品98久久久久久宅男小说| 精品久久久久久电影网| 18禁裸乳无遮挡动漫免费视频| 人妻久久中文字幕网| 亚洲午夜理论影院| 成人特级黄色片久久久久久久 | 成年版毛片免费区| 高清毛片免费观看视频网站 | 热99国产精品久久久久久7| 久久这里只有精品19| 99香蕉大伊视频| 2018国产大陆天天弄谢| 69精品国产乱码久久久| 国产一区有黄有色的免费视频| 欧美午夜高清在线| 久久精品国产综合久久久| 女人精品久久久久毛片| 国产三级黄色录像| 国产在线免费精品| 精品福利观看| 精品久久久精品久久久| 国产精品久久久久久精品古装| 日韩视频在线欧美| 午夜福利在线免费观看网站| 国产成人精品在线电影| 欧美精品啪啪一区二区三区| 国产91精品成人一区二区三区 | 在线观看免费日韩欧美大片| 两人在一起打扑克的视频| 国产亚洲午夜精品一区二区久久| 精品少妇久久久久久888优播| 亚洲色图综合在线观看| 免费日韩欧美在线观看| 丰满饥渴人妻一区二区三| 亚洲少妇的诱惑av| 亚洲欧美日韩另类电影网站| kizo精华| 搡老熟女国产l中国老女人| 精品一区二区三区av网在线观看 | 男男h啪啪无遮挡| 精品国产亚洲在线| 欧美黑人欧美精品刺激| 十八禁人妻一区二区| 欧美另类亚洲清纯唯美| 色视频在线一区二区三区| 色老头精品视频在线观看| 女人高潮潮喷娇喘18禁视频| 国产精品免费一区二区三区在线 | 亚洲成人免费av在线播放| 亚洲久久久国产精品| 啪啪无遮挡十八禁网站| aaaaa片日本免费| 亚洲精品av麻豆狂野| 国产无遮挡羞羞视频在线观看| 久热这里只有精品99| 亚洲成av片中文字幕在线观看| 视频在线观看一区二区三区| 国产亚洲午夜精品一区二区久久| 女性被躁到高潮视频| 精品视频人人做人人爽| 精品免费久久久久久久清纯 | 欧美日韩视频精品一区| √禁漫天堂资源中文www| 色老头精品视频在线观看| 涩涩av久久男人的天堂| 天天添夜夜摸| 日韩有码中文字幕| 国产高清国产精品国产三级| 久久国产精品影院| 1024香蕉在线观看| 久久精品国产亚洲av高清一级| 91麻豆av在线| 免费日韩欧美在线观看| 国产日韩欧美亚洲二区| 亚洲男人天堂网一区| 国产色视频综合| 在线播放国产精品三级| 五月天丁香电影| 久久久精品免费免费高清| 欧美精品一区二区大全| 国产精品秋霞免费鲁丝片| 脱女人内裤的视频| 成人18禁高潮啪啪吃奶动态图| 99久久精品国产亚洲精品| 久久国产精品人妻蜜桃| 99国产精品一区二区三区| 啦啦啦在线免费观看视频4| 在线播放国产精品三级| 国产亚洲精品一区二区www | 深夜精品福利| 久久av网站| 青草久久国产| 一级毛片电影观看| 国产精品1区2区在线观看. | 亚洲自偷自拍图片 自拍| 欧美 日韩 精品 国产| 国产精品二区激情视频| 男人操女人黄网站| 亚洲成人手机| 国产一区二区三区视频了| 久久中文看片网| 亚洲一卡2卡3卡4卡5卡精品中文| 精品国产国语对白av| 18禁观看日本| 性高湖久久久久久久久免费观看| 麻豆乱淫一区二区| 国产亚洲av高清不卡| 精品人妻在线不人妻| 两性夫妻黄色片| 午夜福利视频精品| 亚洲精品一卡2卡三卡4卡5卡| 欧美日韩视频精品一区| 亚洲成国产人片在线观看| 亚洲国产欧美网| 18在线观看网站| 免费黄频网站在线观看国产| av视频免费观看在线观看| 纵有疾风起免费观看全集完整版| 制服人妻中文乱码| 人人妻,人人澡人人爽秒播| 狠狠狠狠99中文字幕| 亚洲精品国产一区二区精华液| 亚洲欧美激情在线| av有码第一页| 自拍欧美九色日韩亚洲蝌蚪91| 久热爱精品视频在线9| 亚洲成av片中文字幕在线观看| 两性夫妻黄色片| 国产1区2区3区精品| 精品人妻1区二区| 老鸭窝网址在线观看| 精品少妇久久久久久888优播| 国产xxxxx性猛交| 十八禁人妻一区二区| 国产亚洲午夜精品一区二区久久| 又黄又粗又硬又大视频| 国产精品香港三级国产av潘金莲| 丝袜人妻中文字幕| 怎么达到女性高潮| 亚洲国产欧美日韩在线播放| 国产三级黄色录像| 性少妇av在线| 超碰成人久久| 国产真人三级小视频在线观看| 一区二区三区精品91| 高潮久久久久久久久久久不卡| 欧美+亚洲+日韩+国产| 极品教师在线免费播放| 国产精品免费大片| 丰满饥渴人妻一区二区三| 人人妻人人澡人人看| 制服人妻中文乱码| 一二三四在线观看免费中文在| 国产一卡二卡三卡精品| 女警被强在线播放| 欧美精品啪啪一区二区三区| 欧美老熟妇乱子伦牲交| 人人妻人人澡人人看| 9热在线视频观看99| 99精品欧美一区二区三区四区| 国产国语露脸激情在线看| 日韩免费高清中文字幕av| 热99久久久久精品小说推荐| 日本wwww免费看| 曰老女人黄片| 国产精品久久久人人做人人爽| av福利片在线| 超碰成人久久| 免费在线观看完整版高清| 在线av久久热| 亚洲精品在线美女| 久久久国产精品麻豆| 性少妇av在线| 757午夜福利合集在线观看| 在线永久观看黄色视频| 欧美日韩福利视频一区二区| 两性午夜刺激爽爽歪歪视频在线观看 | 日本五十路高清| av超薄肉色丝袜交足视频| 91精品国产国语对白视频| 悠悠久久av| 免费观看av网站的网址| 丰满迷人的少妇在线观看| 老熟女久久久| 欧美精品人与动牲交sv欧美| 精品国内亚洲2022精品成人 | 少妇猛男粗大的猛烈进出视频| 国产男靠女视频免费网站| 男女下面插进去视频免费观看| 丰满迷人的少妇在线观看| 亚洲国产成人一精品久久久| 天堂中文最新版在线下载| 色尼玛亚洲综合影院| 亚洲专区中文字幕在线| 久久久久国内视频| 精品国产乱子伦一区二区三区| 美女午夜性视频免费| 在线观看免费日韩欧美大片| 日韩免费高清中文字幕av| 亚洲男人天堂网一区| 18禁黄网站禁片午夜丰满| 黄网站色视频无遮挡免费观看| 亚洲性夜色夜夜综合| 99久久精品国产亚洲精品| 国产精品1区2区在线观看. | 亚洲黑人精品在线| 18禁裸乳无遮挡动漫免费视频| 亚洲精品一卡2卡三卡4卡5卡| 在线永久观看黄色视频| 亚洲三区欧美一区| 久久久久精品人妻al黑| 最黄视频免费看| 老司机影院毛片| 极品人妻少妇av视频| 伦理电影免费视频| 国产成人欧美| 亚洲精品国产精品久久久不卡| 99热国产这里只有精品6| 精品一区二区三区四区五区乱码| 国产精品一区二区在线不卡| 新久久久久国产一级毛片| 男人操女人黄网站| 美女国产高潮福利片在线看| 成人免费观看视频高清| 国产精品欧美亚洲77777| 午夜免费成人在线视频| 男女边摸边吃奶| 美国免费a级毛片| 国产三级黄色录像| 久久午夜综合久久蜜桃| 精品亚洲成a人片在线观看| 大香蕉久久成人网| 曰老女人黄片| 露出奶头的视频| 久久99热这里只频精品6学生| tube8黄色片| 男人操女人黄网站| 亚洲欧美精品综合一区二区三区| 极品教师在线免费播放| 亚洲 欧美一区二区三区| 1024香蕉在线观看| av网站在线播放免费| tube8黄色片| 高清毛片免费观看视频网站 | 亚洲欧美激情在线| 黑丝袜美女国产一区| 免费久久久久久久精品成人欧美视频| 亚洲专区中文字幕在线| 在线观看免费日韩欧美大片| 色老头精品视频在线观看| 90打野战视频偷拍视频| 国产在线精品亚洲第一网站| 国产一区有黄有色的免费视频| 国产欧美日韩综合在线一区二区| 亚洲熟女毛片儿| 久久久久久久精品吃奶| 王馨瑶露胸无遮挡在线观看| 亚洲久久久国产精品| 亚洲天堂av无毛| 国产精品电影一区二区三区 | 巨乳人妻的诱惑在线观看| 18禁黄网站禁片午夜丰满| 免费在线观看视频国产中文字幕亚洲| 黄色视频,在线免费观看| 欧美国产日韩亚洲一区| 日本五十路高清| 两个人视频免费观看高清| 午夜日韩欧美国产| 色吧在线观看| 狂野欧美激情性xxxx| 日韩免费av在线播放| 嫩草影院入口| 亚洲自偷自拍图片 自拍| 亚洲av成人av| 91老司机精品| 午夜免费观看网址| 国产精品永久免费网站| 亚洲国产精品999在线| 在线看三级毛片| 久久精品人妻少妇| 亚洲欧美日韩高清专用| 久久精品91蜜桃| a在线观看视频网站| 黄色成人免费大全| 国产亚洲欧美在线一区二区| 丰满人妻熟妇乱又伦精品不卡| 巨乳人妻的诱惑在线观看| 亚洲一区高清亚洲精品| 久久精品人妻少妇| 国产精品美女特级片免费视频播放器 | 亚洲国产欧美人成| 怎么达到女性高潮| 美女高潮喷水抽搐中文字幕| 国产综合懂色| 国产1区2区3区精品| 成年版毛片免费区| 国产成人福利小说| 午夜成年电影在线免费观看| 女人高潮潮喷娇喘18禁视频| x7x7x7水蜜桃| 免费看日本二区| 日韩国内少妇激情av| 午夜福利免费观看在线| 免费观看精品视频网站| 亚洲av免费在线观看| 中文字幕最新亚洲高清| 他把我摸到了高潮在线观看| 精品99又大又爽又粗少妇毛片 | 日韩成人在线观看一区二区三区| 美女 人体艺术 gogo| 伊人久久大香线蕉亚洲五| 久久性视频一级片| 国产精品亚洲一级av第二区| 变态另类丝袜制服| 国产一区二区三区在线臀色熟女| 精品日产1卡2卡| 亚洲精品在线观看二区| 99在线视频只有这里精品首页| 国产精品国产高清国产av| 亚洲无线在线观看| 脱女人内裤的视频| av中文乱码字幕在线| 久久精品夜夜夜夜夜久久蜜豆| 国产精品亚洲av一区麻豆| 人人妻人人澡欧美一区二区| 免费在线观看成人毛片| 亚洲电影在线观看av| 搡老妇女老女人老熟妇| 午夜福利视频1000在线观看| 岛国在线观看网站| 两个人视频免费观看高清| 亚洲一区二区三区不卡视频| 宅男免费午夜| 美女高潮的动态| 精品一区二区三区视频在线观看免费| 亚洲熟女毛片儿| 日本黄色视频三级网站网址| 在线永久观看黄色视频| 国产精品国产高清国产av| 亚洲国产欧洲综合997久久,| 少妇的丰满在线观看| 亚洲精品一卡2卡三卡4卡5卡| 深夜精品福利| 人妻久久中文字幕网| 1000部很黄的大片| 免费看十八禁软件| 天堂av国产一区二区熟女人妻| 99久久精品一区二区三区| 999久久久国产精品视频| 国产精品久久久久久人妻精品电影| 小蜜桃在线观看免费完整版高清| 男女做爰动态图高潮gif福利片| 最新在线观看一区二区三区| 两个人的视频大全免费| 成人午夜高清在线视频| 亚洲午夜理论影院| 国产高清视频在线观看网站| 怎么达到女性高潮| 午夜福利免费观看在线| 国产精品99久久久久久久久| 91在线精品国自产拍蜜月 | 99热精品在线国产| 一个人免费在线观看的高清视频| 人人妻人人看人人澡| 日本免费a在线| 网址你懂的国产日韩在线| 日韩高清综合在线| 三级国产精品欧美在线观看 | 日韩人妻高清精品专区| 夜夜夜夜夜久久久久| 国产野战对白在线观看| 熟女少妇亚洲综合色aaa.| 此物有八面人人有两片| 久久草成人影院| 国产免费av片在线观看野外av| 色视频www国产| 精品国产三级普通话版| 黑人欧美特级aaaaaa片| 亚洲av美国av| 亚洲中文日韩欧美视频| а√天堂www在线а√下载| 国产精品一区二区精品视频观看| 午夜福利在线观看吧| 一区二区三区高清视频在线| 久久午夜亚洲精品久久| 99久久久亚洲精品蜜臀av| 欧美丝袜亚洲另类 | 免费看光身美女| 嫩草影院入口| 两个人的视频大全免费| 日本黄色片子视频| 黑人操中国人逼视频|