• <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 ?

    Simultaneous enhancement of phosphorescence and chirality by host–guest recognition of molecular tweezers

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

    Diankun Jia, Hua Zhong, Sixun Jiang, Risheng Yao,?, Feng Wang,?

    a School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, China

    b School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China

    c CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, China

    Keywords:Host–guest chemistry Molecular tweezer Room-temperature phosphorescence Chirality Stimuli-responsiveness

    ABSTRACT A novel type of host–guest recognition systems have been developed on the basis of a Au(III) molecular tweezer receptor and chiral Pt(II) guests.The complementary host–guest motifs display high non-covalent binding affinity (Ka: ~104 L/mol) due to the participation of two-fold intermolecular π–π stacking interactions.Both phosphorescence and chirality signals of the Pt(II) guests strengthen in the resulting host–guest complexes, because of the cooperative rigidifying and shielding effects rendered by the tweezer receptor.Their intensities can be reversibly switched toward pH changes, by taking advantage of the electronic repulsion effect between the protonated form of tweezer receptor and the positive-charged guests in acidic environments.Overall, the current study demonstrates the feasibility to enhance and modulate phosphorescence and chirality signals simultaneously via molecular tweezer-based host–guest recognition.

    Host–guest chemistry field has experienced a rapid growth due to the development of various synthetic receptors since the discovery of crown ethers half a centray ago [1–3].These receptors can encapsulate guest molecules with high non-covalent binding affinity and selectivity, endowing diverse functions to the resulting supramolecular host–guest complexes [4–10].Thereinto, promotion of luminescent efficiencyviahost–guest complexation has received considerable attention [11–17].Liu’s and Ma’s groups have encapsulated phosphorescent emitters into the rigid macrocycles such as cyclodextrins and cucurbiturils [15,16].It reduces susceptibility of triplet excitons toward environmental changes, leading to high room-temperature phosphorescent (RTP) emission intensities.Another important functionality of host–guest complexation is to create symmetry breaking and thereby amplify supramolecular chirality.The so-called supramolecular chirogenesis [18–21] occurs between achiral synthetic receptors and chiral guests (orvice versa), showing prospects for absolute configuration determination and asymmetric catalysis applications.Although emission or chirality enhancement of host–guest complexes has been successfully achieved, it remains unexplored to strengthen these two signals in a simultaneous manner, which would be promising for circularly polarized luminescence, multi-channel sensory, and nonlinear optical applications [22–26].

    Molecular tweezers represent an important type of synthetic receptors apart from macrocycles and cages.The two flat and aromatic pincers insynconformation are separated by a rigid or semi-flexible spacer, rendering an open cavity for guest encapsulation by virtue of pre-organization effect [27–29].In recent years,molecular tweezers with metal coordination centers (termed as“metallotweezers”) have attacted tremendous attention becasue of their ease of synthesis and fruitful photophysics [30–32].In this repect, our research group has synthesized a novel metallotweezer 1 (Scheme 1), with two cofacially pincer gold(III) units tethered by a rigid diphenylpyridine spacer [24].It is capable of sandwiching square planar platinum(II) complex 2 (Scheme 1) as the complementary guests.The heterometallic host–guest recognition not only renders rigidification effect for the triplet platinum(II) emitter,but shields it from external quenchers such as oxygen and solvent molecules, giving rise to intense yellow-colored phosphorescence for 2 in both solid and solution states.

    Scheme 1 .Schematic representation for the enhancement and modulation of both phosphorescence and chirality signals upon host–guest recognition between Au(III)molecular tweezer 1 and the complementary Pt(II) guests 3 and 4.The chemical structures of Au(III) tweezer receptor 1 and Pt(II) guests 2–4 are shown in the frame.The counteranions are tetrafluoroborate (BF4?) in compounds 2–4.

    On this basis, herein we sought to prove the generality of tweezer approach to enhance phosphorescence.Meanwhile,supramolecular chirality is induced for the metallotweezer-based host–guest complexes, by incorporating chiral elements into the Pt(II) triplet emitters.Specifically, compounds 3 and 4 (Scheme 1)have been designed and synthesized (Schemes S1, S2 and Figs.S1–S6 in Supporting information), with the presence of two and one(1R)-pinene units [33] on the main ligands, respectively.It is expected to enhance emission and chirality signals simultaneously for the resulting complexes 3?1 and 4?1.Moreover, the metallotweezer receptor 1 features pH-responsive pyridine unit on its rigid spacer [34].In acidic environments, severe electronic repulsion exists between the protonated form of 1 and the positivelycharged guests 3–4.It triggers guest release from the cavity of metallotweezer receptor (Scheme 1), accompanied by the decline of phosphorescent emission and supramolecular chirality intensities.Overall, the current study provides an efficient way to enhance and modulate phosphorescence and chirality signalsviamolecular tweezer-based host–guest complexation.

    Non-covalent host–guest complexation between Au(III) metallotweezer 1 and Pt(II) compound 3 was firstly studiedviaisothermal titration calorimetry (ITC).A negative ITC signal emerged upon progressive addition of 3 into the acetonitrile solution of 1 (Fig.1a and Fig.S7 in Supporting information), illustrating enthalpy-driven host–guest complexation.The abrupt change in the titration curve revealed 1:1 binding stoichiometry between 1 and 3.Fitting the exothermic isotherm data with a one-site model provided the association constant (Ka) value of (3.39 ± 0.21)×104L/mol.

    Fig.1 .(a) ITC data for titrating 3 (2.00 mmol/L in acetonitrile) into an acetonitrile solution of 1 (0.10 mmol/L).(b) UV–vis spectra of 1, 3 and a 1:1 mixture of 1 and 3 in DMSO (c=0.10 mmol/L for each compound).(c) Intensity changes of absorbance at 470 nm, 480 nm, and 490 nm upon addition of 1 (2.00 mmol/L in DMSO) into 3 (0.10 mmol/L in DMSO) at 298 K.The solid lines are obtained via a Matlab-based global analysis program.(d) CD spectra of 3 (blue line) and a 1:1 mixture of 1 and 3 (red line) in acetonitrile.

    Density functional theory (DFT) calculation was employed to clarify the non-covalent complexation mode.In the optimized geometry of complex 3?1 (Fig.2), 3 is encapsulated into the inner cavity of metallotweezer 1 to form a 1:1 sandwiched structure.The centroid-to-plane distances between 3 and the two Au(III) pincers on 1 are determined to be 3.42 ?A and 3.46 ?A, respectively.Hence,two-fold intermolecularπ–πstacking interactions exist between the two [Au(III)(C^N^C)] pincers on 1 and 3.The conclusion was supported by1H NMR measurements (Fig.S8 in Supporting information).Upon adding equivalent amount of Pt(II) compound 3 into Au(III) tweezer 1, the [Au(III)(C^N^C)] pincer protons underwent downfield shifts (Δδ=0.08, and 0.09 ppm for protons H1, and H2,respectively), while protons Ha–don 3 merged into the baseline due to the non-solvation effect.

    Fig.2 .Optimized geometry of complex 3?1 via DFT calculation (left), together with the energy-level diagram of 3 and 3?1 via TD-DFT computation (right).The black lines and blue lines mark the energy levels of HOMOs and LUMOs, respectively.

    Non-covalent complexation between 1 and 3 gave rise to UV–vis spectroscopic changes.For Au(III)-based metallotweezer 1, a vibronic structured UV–vis absorbance was present between 350 and 420 nm (Fig.1b).With reference to the previous literatures[35,36], this band is typical for metal–perturbedπ→π?intraligand (IL) transition of the [Au(III)(C^N^C)(C≡C–R)] units.In the meantime, Pt(II) compound 3 displayed a visible-light absorbance in the range of 385–500 nm (Fig.1b), assigning to the admixture of dπ(Pt)→π?(tpy) metal?to?ligand charge transfer (MLCT) andπ(C≡CR)→π?(tpy) ligand?to?ligand charge transfer (LLCT) transitions (Fig.2) [37–39].Upon mixing equimolar amounts of 1 and 3 together in DMSO, a shoulder absorption band appeared at the low-energy region (ranging between 455 nm and 530 nm, Fig.1b).Depending on TD-DFT calculations (Fig.2), both HOMO and LUMO of complex 3?1 are essentially identical to those of compound 3,in which the HOMO is the mixture of phenylacetyleneπorbital and Pt(II) dπorbital, while the LUMO isπ?orbital of the terpyridine ligand.The results denote the negligible contribution of metallotweezer 1 to the frontier orbitals of 3?1.The bathochromic absorption of 3?1 could be probably ascribed to the physical perturbance effectvianon-covalent host?guest complexation.

    On this basis, the non-covalent binding affinity of 3?1 was probedviaUV–vis titration experiments.TheKavalue was determined to be 1.13×104(± 9.9%) L/mol, by fitting the collected UV–vis absorbances at 470, 480, and 490 nm with the global analysis method (Fig.1c and Fig.S9a in Supporting information).TheKavalues acquired by UV–vis and ITC measurements are within the same order of magnitude, validating strong non-covalent complexation strength of 3?1.In view of the presence of optically active(1R)-pinene unit on the Pt(II) guest, CD spectroscopy was further performed for both compound 3 and complex 3?1.As shown in Fig.1d, very weak Cotton effect was detected for 3 itself.Upon adding an equimolar amount of 1 into 3, the CD signal exhibited drastic enhancement for both low-energy MLCT/LLCT and highenergy IL transitions (positive maxima at 340 nm and 442 nm,together with negative maximum at 322 nm,Δε=9.99, 1.75 and–4.64 cm?1L mol?1, respectively).The effective chirality transfer from the aliphatic (1R)-pinene to the aromatic Pt(II) pincer is attributed to the restriction of carbon–carbon and carbon–platinum bond rotations in the individual guest 3.Accordingly, the amplified CD signal of 3?1 reflects the emergence of supramolecular chirality upon metallotweezer–guest complexation.

    Intriguingly, the resulting host–guest complex 3?1 displayed emission enhancement behaviours.As shown in Fig.3a, the metallotweezer receptor 1 was non-emissive in fluid solution [emission quantum yield (Фem)<0.001], ascribed to the presence of thermally-accessibled-dor LLCT (ligand-to-ligand charge transfer)states for the Au(III) pincers [40].Meanwhile, the Pt(II) guest 3 exhibited moderate emission in deaerated acetonitrile (λmax=583 nm,Фem=0.07, the average lifetimeτ=0.27 μs, Figs.3a and b).Upon mixing equimolar amounts of 1 and 3 together, an intense orange-coloured emission appeared for the mixture solution(λmax=602 nm, Fig.3a).TheФemvalue of 3?1 was determined to be 0.61 in degassed acetonitrile, significantly higher than those of the individual compounds under the same conditions.Lifetime measurement of 3?1 (τ= 2.01 μs, Fig.3b) proved the phosphorescent emission character.Notably, in aerated acetonitrile the phosphorescence quantum yield was 0.35, demonstrating the efficiency to resist oxygen upon host–guest complexation (Fig.S12 in Supporting information).

    Fig.3 .(a) Emission spectra (λex=450 nm) of 1, 3 and 3?1 in degassed acetonitrile(0.04 mmol/L for each compound).(b) Time-dependent emission lifetime decay of 3?1 and 3 under deaerated condition.The excited-state decay profile was fitted by a biexponential function to provide the average lifetime.Excitation wavelength was 355 nm picosecond laser.(c) CD and d) emission spectral changes of 3?1 (0.04 mmol/L in acetonitrile) upon the successive addition of the acetonitrile solutions of TFA and TEA (0.50 mol/L for each solution, 2 μL for each injection).Inset of c: CD intensity changes at 340 nm.Inset of d: emission intensity changes at 625 nm."G","H-G", "Acid", and "Base" refer to 3, complex 3?1, TFA and TEA, respectively.

    We further acquired radiative (kr) and non-radiation (knr) decay rates of 3?1 to clarify the mechanism for metallotweezerenhanced phosphorescence.In particular, thekrandknrvalues of 3?1 were determined to be 3.03×105s?1and 1.94×105s?1, respectively.Thekrvalue was comparable to that of the individual guest 3 (kr: 2.59×105s?1).It denotes that the Pt(II) phosphor contributes predominately to the emitting T1state of 3?1.Meanwhile,theknrvalue of 3?1 was 18-fold lower than that of 3 (3.44×106s?1).We rationalized that vibrational and rotational stretching of Pt(II) phosphor is restricted to reduce non-radiative relaxations.Meanwhile, the Pt(II) triplet emitter is shielded from the polar solvents.Accordingly, it facilitates phosphorescent emission enhancement upon non-covalent host–guest complexation between 1 and 3.

    Non-covalent recognition was also examined between metallotweezer receptor 1 and Pt(II) guest 4.Similar to that of 3?1, 4 is sandwiched into the cavity of 1 with two-foldπ-stacking interactions (the centroid-to-plane distances between 4 and the two Au(III) pincers on 1: 3.43 ?A and 3.52 ?A, Fig.S10 in Supporting information).TheKavalue of complex 4?1 was determined to be 1.37×104(± 8.4%) L/mol on the basis of UV–vis titration measurements (Fig.S9b in Supporting information).The comparableKavalues between 4?1 and 3?1 illustrate that non-covalent host–guest binding strength is hardly influenced by the number of (1R)-pinene units on the Pt(II) guest structure.Complex 4?1 also exhibited the simultaneous enhancement of chirality and phosphorescence signals (λmax=628 nm in acetonitrile,Фem: 0.05 for 4versus0.43 for 4?1 in deaerated conditions, Figs.S11b and Fig.S14b in Supporting information).

    It should be mentioned both complexes 3?1 and 4?1 exhibited red-shifted emission as compared to the individual Pt(II) guests.The phenomena were different from the blue-shifted emission of 2?1 (λmax: from 589 nm of 2 to 572 nm of 2?1) [24].Generally, emission enhancement of host–guest complexes is ascribed to the synergistic shielding and rigidifying effects endowed by metallotweezer receptor 1.In the case of complex 2?1, the Pt(II) guest 2 renders large steric hindrance effect, which potentially leads to the predominance of the rigidifying effects.In comparison, the Pt(II)guests 3 and 4 possess relatively lower steric hindrance, resulting in the predominant contribution of non-covalent shielding effect.Despite the wavelength difference, the results prove the generality to enhance emission intensity of Pt(II) triplet emittersviametallotweezer host–guest complexation.

    Next, we turned to study stimuli-responsiveness of the resulting host–guest complexes.When 2 equiv.of trifluoroacetic acid (TFA)was added, the amplified CD signals of complexes 3?1 in acetonitrile disappeared (Fig.3c).Meanwhile, the visible light absorbance signal in acidic environment resembled the MLCT/LLCT absorbance of the individual compound 3 (Fig.S17 in Supporting information),suggesting pH-triggered release of the Pt(II) guest.Because of the absence of shielding and rigidifying effects rendered by the metallotweezer receptor, the intense emission at 602 nm of 3?1 declined significantly (Fig.3d).The successive addition of trimethylamine (TEA) led to the re-encapsulation of Pt(II) phosphor.As a consequence, the absorption, CD, and emission bands of complex 3?1 recovered (Figs.3c and d, Figs.S17a and b).The on-off switching processes were reproducible for four repeating cycles (Fig.3d,inset).The reversible modulation of chirality and phosphorescent signals also took place for complex 4?1 (Figs.S17c and d).

    The pH-responsive mechanism of complexes 3?1 and 4?1 was further elucidated.As can be seen, neither UV–Vis nor emission spectroscopic changes occurred for the individual compounds 3 and 4 upon adding TFA (Fig.S16 in Supporting information).Hence,the acids not function directly on the triplet emitters.We rationalized that TFA protonated metallotweezer 1, exerting an indirect effect to modulate the optical signals of Pt(II) guests.To prove this assertion,1H NMR measurements were performed for the control compound 5 (Fig.S15 in Supporting information).As can be seen, upon adding 2 equiv.TFA, the resonances of protons H7’and H8’underwent upfield shifts (Δδ=–0.04 and –0.06 ppm for H7’and H8’, respectively), while protons H11’exhibited downfield shifts(0.08 ppm).The result demonstrates protonation of diphenylpyridine unit on metallotweezer 1, thus imparting large electronic repulsion to the positively-charged Pt(II) compounds in acidic environments.

    In summary, two host–guest complexes have been successfully constructed on the basis of Au(III) tweezer 1 and chiral Pt(II) compounds 3–4 with high binding affinity (Ka: ~104L/mol).The resulting complexes 3?1 and 4?1 exhibit orange-colored phosphorescence, with the enhancement of the emission intensities compared to the corresponding Pt(II) guests.Supramolecular chirality signals simultaneously emerged due to the restriction of free bond rotations.Both phosphorescent emission and chirality signals can be modulated toward pH changes, by taking advantage of the electronic repulsion effect between the protonated form of 1 and the positively-charged guests 3 and 4 in acidic environments.Overall, metallotweezer-based host–guest complexation provides an efficient method to enhance and modulate phosphorescence and chirality signals in a concurrent manner, which benefits the fabrication of circularly polarized phosphorescence and multi-channel sensory materials.

    Declaration of competing interest

    The authors declared that they have no conflicts of interest to this work.

    Acknowledgments

    This work was financially supported by the National Natural Science Foundation of China (Nos.21922110 and 21871245),the Fundamental Research Funds for the Central Universities (No.WK3450000005), and the Starry Night Science Fund at Shanghai Institute for Advanced Study, Zhejiang University (No.SNZJU-SIAS-006).

    Supplementary materials

    Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2022.02.081.

    亚洲国产精品999在线| 丁香六月欧美| 88av欧美| 日日摸夜夜添夜夜添小说| 黑丝袜美女国产一区| 亚洲精品一区av在线观看| 成熟少妇高潮喷水视频| 中文字幕人成人乱码亚洲影| 一进一出抽搐动态| 亚洲第一av免费看| 成人精品一区二区免费| av网站免费在线观看视频| 搡老岳熟女国产| 精品国产一区二区久久| 精品国产亚洲在线| 欧美黄色淫秽网站| videosex国产| 少妇粗大呻吟视频| 久久伊人香网站| 一个人观看的视频www高清免费观看 | 亚洲成人免费电影在线观看| 日本撒尿小便嘘嘘汇集6| 99精品欧美一区二区三区四区| 久热爱精品视频在线9| 欧美另类亚洲清纯唯美| 一个人观看的视频www高清免费观看 | 午夜视频精品福利| 精品一区二区三区av网在线观看| 在线av久久热| 日本 欧美在线| 久久久久久国产a免费观看| 不卡一级毛片| 亚洲av成人一区二区三| 欧美中文日本在线观看视频| 亚洲av第一区精品v没综合| 欧美黑人精品巨大| 亚洲午夜理论影院| 国产高清有码在线观看视频 | 日韩 欧美 亚洲 中文字幕| 好看av亚洲va欧美ⅴa在| 亚洲欧美激情综合另类| 国产av精品麻豆| 久久久国产欧美日韩av| 熟妇人妻久久中文字幕3abv| 久9热在线精品视频| 日本欧美视频一区| 在线观看66精品国产| 啦啦啦观看免费观看视频高清 | 精品久久久久久成人av| 日日干狠狠操夜夜爽| 亚洲视频免费观看视频| 12—13女人毛片做爰片一| 欧美国产日韩亚洲一区| 啪啪无遮挡十八禁网站| 午夜福利高清视频| 亚洲av五月六月丁香网| 美女扒开内裤让男人捅视频| av视频在线观看入口| 国产精品久久久久久精品电影 | 夜夜躁狠狠躁天天躁| 久久午夜亚洲精品久久| 黄色成人免费大全| 欧美久久黑人一区二区| 欧美激情高清一区二区三区| 免费在线观看日本一区| 久久精品亚洲熟妇少妇任你| 亚洲人成伊人成综合网2020| 叶爱在线成人免费视频播放| 国产在线观看jvid| 亚洲国产精品合色在线| 日本撒尿小便嘘嘘汇集6| 亚洲七黄色美女视频| 国产黄a三级三级三级人| 人人妻,人人澡人人爽秒播| 中文字幕av电影在线播放| 男人操女人黄网站| 欧美激情高清一区二区三区| 日韩欧美一区视频在线观看| 国产精品免费视频内射| 制服人妻中文乱码| 久9热在线精品视频| www.999成人在线观看| 老司机靠b影院| 亚洲av片天天在线观看| 成年女人毛片免费观看观看9| 99国产精品免费福利视频| 成年版毛片免费区| 男人的好看免费观看在线视频 | 啦啦啦韩国在线观看视频| 午夜a级毛片| 亚洲av熟女| 亚洲国产高清在线一区二区三 | 午夜老司机福利片| 老汉色∧v一级毛片| 一级作爱视频免费观看| 亚洲全国av大片| 亚洲人成伊人成综合网2020| 精品人妻在线不人妻| 午夜福利成人在线免费观看| 19禁男女啪啪无遮挡网站| 少妇熟女aⅴ在线视频| 亚洲一码二码三码区别大吗| 老司机深夜福利视频在线观看| 大型av网站在线播放| 国产精品乱码一区二三区的特点 | 免费观看人在逋| 成年版毛片免费区| 国产色视频综合| 最好的美女福利视频网| 十分钟在线观看高清视频www| 日本欧美视频一区| 欧美久久黑人一区二区| 极品教师在线免费播放| 侵犯人妻中文字幕一二三四区| 国产成人av教育| 午夜免费观看网址| 国产激情欧美一区二区| 欧美日韩中文字幕国产精品一区二区三区 | 一区二区三区国产精品乱码| 国产精品自产拍在线观看55亚洲| 国内精品久久久久精免费| 国产亚洲欧美在线一区二区| 日本三级黄在线观看| 午夜a级毛片| 中文字幕久久专区| 亚洲欧美一区二区三区黑人| 少妇熟女aⅴ在线视频| 狠狠狠狠99中文字幕| 色哟哟哟哟哟哟| 国产成人一区二区三区免费视频网站| 色在线成人网| 国产国语露脸激情在线看| 日本免费一区二区三区高清不卡 | 啦啦啦观看免费观看视频高清 | 波多野结衣av一区二区av| 欧美色欧美亚洲另类二区 | 久久久久久久久久久久大奶| 一本综合久久免费| 少妇裸体淫交视频免费看高清 | 免费看十八禁软件| 国产男靠女视频免费网站| 黄色a级毛片大全视频| 人人妻人人爽人人添夜夜欢视频| 精品不卡国产一区二区三区| 国产精品久久电影中文字幕| 90打野战视频偷拍视频| 不卡一级毛片| 国产成人av激情在线播放| 久久中文字幕人妻熟女| 亚洲精品中文字幕在线视频| 91老司机精品| 亚洲av第一区精品v没综合| 国产又爽黄色视频| 在线观看舔阴道视频| 啪啪无遮挡十八禁网站| 韩国精品一区二区三区| 黄色丝袜av网址大全| 在线观看66精品国产| 好男人在线观看高清免费视频 | 精品一区二区三区四区五区乱码| 女生性感内裤真人,穿戴方法视频| 老熟妇乱子伦视频在线观看| 久久伊人香网站| 99国产综合亚洲精品| 欧美日韩黄片免| 久久精品亚洲精品国产色婷小说| 久久热在线av| 一进一出抽搐动态| 啪啪无遮挡十八禁网站| 国产精品日韩av在线免费观看 | 18禁裸乳无遮挡免费网站照片 | 成年人黄色毛片网站| 久久精品国产清高在天天线| 色老头精品视频在线观看| 欧美中文日本在线观看视频| 久久天躁狠狠躁夜夜2o2o| 亚洲第一青青草原| 欧美精品亚洲一区二区| 国产国语露脸激情在线看| 日韩精品免费视频一区二区三区| 免费一级毛片在线播放高清视频 | 久久精品国产亚洲av高清一级| 国产一级毛片七仙女欲春2 | 欧美老熟妇乱子伦牲交| 国产乱人伦免费视频| 精品午夜福利视频在线观看一区| 亚洲av成人av| 欧美成人午夜精品| 日日摸夜夜添夜夜添小说| 日本一区二区免费在线视频| 免费看a级黄色片| 9色porny在线观看| 两性夫妻黄色片| 国产精品,欧美在线| 日韩精品中文字幕看吧| 欧美成人性av电影在线观看| 久久久国产欧美日韩av| 免费一级毛片在线播放高清视频 | 性欧美人与动物交配| 90打野战视频偷拍视频| 自线自在国产av| 18美女黄网站色大片免费观看| 18禁观看日本| 高清在线国产一区| 一级,二级,三级黄色视频| 一区二区日韩欧美中文字幕| 欧美成人午夜精品| 首页视频小说图片口味搜索| 亚洲激情在线av| 色老头精品视频在线观看| 在线播放国产精品三级| 在线观看午夜福利视频| 岛国视频午夜一区免费看| 久久久久国产精品人妻aⅴ院| 日韩有码中文字幕| 搡老岳熟女国产| 国产日韩一区二区三区精品不卡| 国产精品日韩av在线免费观看 | 国产高清videossex| 亚洲av成人av| 国产高清视频在线播放一区| 欧洲精品卡2卡3卡4卡5卡区| 欧美一区二区精品小视频在线| 老汉色av国产亚洲站长工具| 纯流量卡能插随身wifi吗| 午夜福利影视在线免费观看| 日韩欧美三级三区| 老司机在亚洲福利影院| 如日韩欧美国产精品一区二区三区| 亚洲男人天堂网一区| 久热爱精品视频在线9| 日本vs欧美在线观看视频| 亚洲男人天堂网一区| 999精品在线视频| 自拍欧美九色日韩亚洲蝌蚪91| 午夜亚洲福利在线播放| 成人国产一区最新在线观看| 50天的宝宝边吃奶边哭怎么回事| 大陆偷拍与自拍| 亚洲最大成人中文| 热99re8久久精品国产| 亚洲精品国产精品久久久不卡| 又紧又爽又黄一区二区| 亚洲欧美日韩高清在线视频| 日韩av在线大香蕉| 国产精品香港三级国产av潘金莲| 精品欧美一区二区三区在线| 国产av又大| 亚洲精品一区av在线观看| 日韩大尺度精品在线看网址 | www国产在线视频色| 两个人视频免费观看高清| 亚洲五月色婷婷综合| 99精品久久久久人妻精品| av视频免费观看在线观看| 熟妇人妻久久中文字幕3abv| 69精品国产乱码久久久| 久久久国产精品麻豆| 99久久99久久久精品蜜桃| 香蕉国产在线看| 亚洲国产精品sss在线观看| 女人被狂操c到高潮| 999久久久国产精品视频| 欧美大码av| 大香蕉久久成人网| 国产欧美日韩一区二区三| 黄色成人免费大全| 91麻豆av在线| 免费观看人在逋| 国产精品影院久久| 夜夜看夜夜爽夜夜摸| 亚洲国产日韩欧美精品在线观看 | 91精品三级在线观看| 99国产极品粉嫩在线观看| 成人国产综合亚洲| 两性夫妻黄色片| www.自偷自拍.com| 久久精品国产综合久久久| 成人三级做爰电影| 国产精华一区二区三区| 免费女性裸体啪啪无遮挡网站| 亚洲视频免费观看视频| 18禁观看日本| 不卡av一区二区三区| 99久久综合精品五月天人人| 亚洲人成电影观看| 在线天堂中文资源库| 成年版毛片免费区| 国产成人av激情在线播放| 国产区一区二久久| 99香蕉大伊视频| 又大又爽又粗| 大型av网站在线播放| 制服丝袜大香蕉在线| 国产成年人精品一区二区| 国产精品久久久久久亚洲av鲁大| 国语自产精品视频在线第100页| 精品高清国产在线一区| av超薄肉色丝袜交足视频| 国产精品久久久久久精品电影 | 最近最新中文字幕大全电影3 | 亚洲精品国产精品久久久不卡| 免费av毛片视频| ponron亚洲| 九色亚洲精品在线播放| 99精品在免费线老司机午夜| 中出人妻视频一区二区| 嫁个100分男人电影在线观看| 亚洲av日韩精品久久久久久密| 久久人人精品亚洲av| 丝袜在线中文字幕| 一二三四在线观看免费中文在| 好看av亚洲va欧美ⅴa在| 国产精品久久电影中文字幕| 国产国语露脸激情在线看| 亚洲五月天丁香| 欧美激情极品国产一区二区三区| 美女午夜性视频免费| 精品久久久精品久久久| 亚洲成av人片免费观看| 19禁男女啪啪无遮挡网站| 亚洲精品一区av在线观看| 一级a爱视频在线免费观看| 丰满人妻熟妇乱又伦精品不卡| 麻豆av在线久日| 久久精品影院6| 一级a爱片免费观看的视频| 久久久久亚洲av毛片大全| 成人国产一区最新在线观看| 波多野结衣高清无吗| 国产精品98久久久久久宅男小说| 窝窝影院91人妻| 中文字幕最新亚洲高清| 一级作爱视频免费观看| 99国产精品一区二区蜜桃av| 国产亚洲精品久久久久5区| 一个人免费在线观看的高清视频| 国产精品日韩av在线免费观看 | 国产在线观看jvid| 亚洲 欧美 日韩 在线 免费| 免费一级毛片在线播放高清视频 | 欧美一级毛片孕妇| 国产精品日韩av在线免费观看 | 国产激情欧美一区二区| 国产单亲对白刺激| 国产极品粉嫩免费观看在线| 国产成人影院久久av| 久久久国产精品麻豆| 天堂动漫精品| 日韩欧美一区视频在线观看| 婷婷精品国产亚洲av在线| 女人被躁到高潮嗷嗷叫费观| 巨乳人妻的诱惑在线观看| 久久人妻福利社区极品人妻图片| 亚洲成av人片免费观看| a级毛片在线看网站| 老鸭窝网址在线观看| 午夜精品久久久久久毛片777| 如日韩欧美国产精品一区二区三区| 久久久久久亚洲精品国产蜜桃av| 我的亚洲天堂| 国产在线精品亚洲第一网站| 国产亚洲av嫩草精品影院| 日韩视频一区二区在线观看| 91av网站免费观看| 亚洲av美国av| 天堂动漫精品| 亚洲视频免费观看视频| 国产高清激情床上av| 99国产极品粉嫩在线观看| 亚洲中文字幕一区二区三区有码在线看 | 九色国产91popny在线| √禁漫天堂资源中文www| 日本vs欧美在线观看视频| 欧美乱妇无乱码| 亚洲第一青青草原| 午夜影院日韩av| 男女午夜视频在线观看| 曰老女人黄片| 波多野结衣巨乳人妻| 90打野战视频偷拍视频| 变态另类成人亚洲欧美熟女 | 搡老岳熟女国产| 免费一级毛片在线播放高清视频 | 欧美人与性动交α欧美精品济南到| 一区二区日韩欧美中文字幕| 亚洲国产精品合色在线| 国产成人啪精品午夜网站| 久久精品成人免费网站| 午夜免费成人在线视频| 国产成人啪精品午夜网站| 大型av网站在线播放| 18禁国产床啪视频网站| 一进一出抽搐gif免费好疼| 窝窝影院91人妻| 在线观看免费日韩欧美大片| 国产蜜桃级精品一区二区三区| 涩涩av久久男人的天堂| 精品不卡国产一区二区三区| 国产精品1区2区在线观看.| 欧美成人午夜精品| 亚洲av五月六月丁香网| 久久精品亚洲精品国产色婷小说| 老司机午夜福利在线观看视频| 国产一区在线观看成人免费| 午夜福利视频1000在线观看 | av在线天堂中文字幕| 亚洲 欧美 日韩 在线 免费| 在线国产一区二区在线| 91精品国产国语对白视频| 亚洲va日本ⅴa欧美va伊人久久| 超碰成人久久| 天天一区二区日本电影三级 | 丁香六月欧美| 欧美中文综合在线视频| 国产精品永久免费网站| 在线观看免费日韩欧美大片| 亚洲精品中文字幕一二三四区| 18美女黄网站色大片免费观看| 叶爱在线成人免费视频播放| 国产精品精品国产色婷婷| 国产精品爽爽va在线观看网站 | 亚洲专区字幕在线| 淫妇啪啪啪对白视频| 精品久久久久久久久久免费视频| 美国免费a级毛片| 激情在线观看视频在线高清| 亚洲一区二区三区不卡视频| 国产精品99久久99久久久不卡| 亚洲国产高清在线一区二区三 | 久久人人精品亚洲av| 久久久久久久久免费视频了| 韩国av一区二区三区四区| 亚洲精品国产区一区二| 在线视频色国产色| 女性生殖器流出的白浆| 欧美成人性av电影在线观看| 黄色片一级片一级黄色片| 国产精品一区二区在线不卡| 亚洲自偷自拍图片 自拍| 老汉色∧v一级毛片| 午夜a级毛片| 久久中文字幕一级| 禁无遮挡网站| 午夜成年电影在线免费观看| 丝袜美足系列| 成人av一区二区三区在线看| 精品乱码久久久久久99久播| 两个人视频免费观看高清| 久9热在线精品视频| 欧美久久黑人一区二区| 婷婷精品国产亚洲av在线| 日本a在线网址| 黑人欧美特级aaaaaa片| 国产av在哪里看| 亚洲黑人精品在线| 国产熟女午夜一区二区三区| 精品久久久久久成人av| 亚洲三区欧美一区| 久久久久久久午夜电影| 国产亚洲欧美精品永久| 成人特级黄色片久久久久久久| 啦啦啦 在线观看视频| 中出人妻视频一区二区| 中文亚洲av片在线观看爽| 国产一区二区三区在线臀色熟女| 精品欧美一区二区三区在线| 亚洲精品中文字幕在线视频| 中文字幕另类日韩欧美亚洲嫩草| 久久人妻av系列| 亚洲自拍偷在线| 国产色视频综合| 成人永久免费在线观看视频| 国产一卡二卡三卡精品| 两人在一起打扑克的视频| 一二三四在线观看免费中文在| 长腿黑丝高跟| 午夜成年电影在线免费观看| 伊人久久大香线蕉亚洲五| 啪啪无遮挡十八禁网站| 国产精品野战在线观看| 国产精品香港三级国产av潘金莲| 久久久国产成人免费| 亚洲一区中文字幕在线| 人人妻人人爽人人添夜夜欢视频| 操美女的视频在线观看| 亚洲欧美激情在线| 国产一区二区三区在线臀色熟女| 国产精品 欧美亚洲| 丝袜在线中文字幕| 极品教师在线免费播放| 国产片内射在线| 天天躁狠狠躁夜夜躁狠狠躁| 久久久久国内视频| 欧美一级a爱片免费观看看 | 18禁美女被吸乳视频| 精品午夜福利视频在线观看一区| 免费无遮挡裸体视频| 国产精品爽爽va在线观看网站 | 变态另类丝袜制服| 成人亚洲精品av一区二区| 麻豆久久精品国产亚洲av| 亚洲一码二码三码区别大吗| 一区二区三区国产精品乱码| 免费av毛片视频| 成人国语在线视频| 亚洲人成网站在线播放欧美日韩| 男女之事视频高清在线观看| 免费在线观看日本一区| 两个人免费观看高清视频| 十分钟在线观看高清视频www| 久久香蕉精品热| 午夜亚洲福利在线播放| 看片在线看免费视频| xxx96com| 色哟哟哟哟哟哟| 国产精品久久久久久人妻精品电影| 色综合婷婷激情| 欧美午夜高清在线| 亚洲成国产人片在线观看| 亚洲专区中文字幕在线| 一级,二级,三级黄色视频| 超碰成人久久| 淫秽高清视频在线观看| 亚洲欧美日韩高清在线视频| 久久亚洲精品不卡| 性欧美人与动物交配| 大型黄色视频在线免费观看| 色播亚洲综合网| 亚洲一区二区三区不卡视频| 国产亚洲欧美在线一区二区| 成人18禁在线播放| 午夜福利欧美成人| 亚洲一卡2卡3卡4卡5卡精品中文| 又紧又爽又黄一区二区| 大型av网站在线播放| 久久精品亚洲精品国产色婷小说| 国产三级黄色录像| 久久人妻av系列| 亚洲国产精品sss在线观看| 黄色片一级片一级黄色片| 亚洲 欧美 日韩 在线 免费| 高清黄色对白视频在线免费看| 在线观看舔阴道视频| 啦啦啦 在线观看视频| 久久人人爽av亚洲精品天堂| 国产高清激情床上av| 两人在一起打扑克的视频| av天堂在线播放| 国产区一区二久久| 美女大奶头视频| 亚洲av电影不卡..在线观看| 91成人精品电影| 别揉我奶头~嗯~啊~动态视频| 一级黄色大片毛片| 国产精品久久久久久人妻精品电影| 亚洲av成人一区二区三| 长腿黑丝高跟| 久久人人爽av亚洲精品天堂| 久久精品国产亚洲av香蕉五月| 一卡2卡三卡四卡精品乱码亚洲| 国产男靠女视频免费网站| 人人妻人人澡人人看| 老熟妇仑乱视频hdxx| 99在线视频只有这里精品首页| 久久香蕉精品热| 久久精品91无色码中文字幕| 又黄又爽又免费观看的视频| 黄频高清免费视频| 午夜日韩欧美国产| 视频区欧美日本亚洲| 成人欧美大片| 天堂动漫精品| 亚洲欧美日韩高清在线视频| 亚洲成人国产一区在线观看| 成年女人毛片免费观看观看9| 精品久久久久久久人妻蜜臀av | АⅤ资源中文在线天堂| av网站免费在线观看视频| 亚洲色图综合在线观看| 99精品欧美一区二区三区四区| 亚洲第一电影网av| 97人妻精品一区二区三区麻豆 | 亚洲成av片中文字幕在线观看| 精品第一国产精品| 国产精品久久久人人做人人爽| 自拍欧美九色日韩亚洲蝌蚪91| 精品国产一区二区三区四区第35| 成人国语在线视频| 免费少妇av软件| 精品午夜福利视频在线观看一区| 欧美在线黄色| 校园春色视频在线观看| 一a级毛片在线观看| 精品午夜福利视频在线观看一区| 91成人精品电影| 十分钟在线观看高清视频www| 好男人电影高清在线观看| 18禁黄网站禁片午夜丰满| 一边摸一边做爽爽视频免费| a在线观看视频网站| 夜夜看夜夜爽夜夜摸| 在线观看免费日韩欧美大片| 一区二区三区激情视频| 一区二区三区精品91| 亚洲三区欧美一区| 成年人黄色毛片网站| 999精品在线视频| 国产熟女午夜一区二区三区| 999精品在线视频| 在线观看免费午夜福利视频| 乱人伦中国视频| 国产单亲对白刺激| 久热这里只有精品99| 制服人妻中文乱码|