• <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 ?

    Zirconium metal organic cages: From phosphate selective sensing to derivate forming

    2022-09-15 03:11:24ZiyuanGaoJiaJiaWentongFanTongLiaoXingfengZhang
    Chinese Chemical Letters 2022年9期

    Ziyuan Gao, Jia Jia, Wentong Fan, Tong Liao, Xingfeng Zhang

    College of Material and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, China

    ABSTRACT Luminescent metal organic cages (MOCs) have attracted great interest as a unique class of sensing substrates.In this work, intrinsically fluorescent Zr-MOCs were successfully used as fluorescent probes for the sensitive and selective detection of phosphate anions in water and real samples.When the ligand and Zr ion clusters form a cage, the intrinsic fluorescence of the ligand was tuned from high to weak emission due to the ligand-to-metal charge transfer (LMCT) effect, and this weakened fluorescence can be restored by the addition of phosphate.The degree of fluorescence enhancement is positively correlated with the added phosphate concentration, and the efficacy of this strategy is demonstrated by a linear phosphate detection range of 5–500 μmol/L and a detection limit of 1.06 μmol/L.We discuss the interaction between phosphate and Zr in scattering spectrum and MS, respectively.In comparison to phosphate adsorption on Zr-metal organic frameworks (MOFs), where phosphate connects different numbers of cages, both blocking the LMCT effect and causing the cages to aggregate.We also found that the phosphate displaces the ligand from the cage when the phosphate concentration is further expanded, resulting in the formation of new derivatives.This derivative was shown to be useful as a Lewis acid catalyst and as a rare earth ion adsorbent.

    Keywords:Zirconium metal organic cage Phosphate sensing Derivant forming Fluorescence enhancement Mass spectrometry

    Phosphate plays an important role in biological systems and its concentration levels in body fluids can help diagnose such as rickets or hyperphosphatemia [1].In addition, although phosphate is widely present in natural environmental waters, high concentrations of phosphate can cause eutrophication in water bodies [2].Nowadays, most of the methods used to detect phosphate are ion chromatography or electrochemical analysis, which have long detection time and expensive instruments [3].It is faster and more efficient to use nanoparticles or small molecules with fluorescent properties for highly selective and sensitive sensing.However, because of the strong hydration of the anion in aqueous solution,highly selective sensing requires strong affinity of the phosphate for the probe.

    Metal organic cages (MOCs) are another kind of rapidly developing porous materials after zeolite, metal organic frameworks(MOFs) and covalent organic frameworks (COFs) [4–7].Similar to MOFs, MOCs are discrete molecular combinations of metal ions or metal clusters and organic ligands with a specific morphology and cavity [8].UiO-66, as a star molecule of Zr-MOFs, built by trinuclear zirconium clusters are highly stable due to the high Zr?O bond energy (776 kJ/mol), showing excellent stability in aqueous solutions with neutral, acidic and weak basic conditions [9–11].Similarly, as a substructure of Zr-MOF, Zr-MOC should also have the same chemical stability as UiO.Recently, a class of Zr-MOCs has been reported, which possess various geometries with excellent properties in catalytic, sensing and adsorption [12–15].Highly stable Zr-MOCs have captivated more consideration not only for their robustness but also for reasonable solubility, permanent porosity,functionalization and potent applications in gas adsorption and selective separation.

    In previous literatures, Zr-MOFs have been shown to form Zr?O?P bonds with phosphate groups, resulting in an extremely strong affinity.So far, Zr-MOFs have been used to selectively isolate and sense a variety of substances containing phosphate groups such as chlorophosphates, organophosphorus pesticides and phosphopeptides, but extremely high concentrations of phosphates can destroy the structure of MOFs [16–20].The fluorescence (FL) of terephthalic acid (BDC) as the ligand in the free state is weakened by the ligand-to-metal charge transfer (LMCT) when forming MOFs with Zr clusters.After the addition of phosphate, the LMCT effect is weakened once the phosphate is bound to the zirconium cluster,and thus the FL of BDC is restored.Taking advantage of this effect, Gu and his co-workers used UiO-66-NH2as a probe to detect phosphate [21].MOFs as a 3-dimensional structured nanomaterial,phosphate takes some time to diffuse into the interior of MOF to bind to the Zr clusters, allowing the FL of most of the ligands to be restored, while MOC as a 0-dimensional molecule and with multiple pore windows leading to a central internal cavity [22,23], have been demonstrated as water channels with high water permeability thus the Zr clusters bind more fully to the phosphate, and the FL of the ligand can be restored in a short time by complete binding [24].

    Fig.1.ESI-MS analysis of as-synthesized ZrT-1-NH2: (a) observed MS data, (b) simulated MS data.

    Here we report a Zr-MOC, ZrT-1-NH2, synthesized with BDCNH2as ligand, as a fluorescent probe to sense phosphate in aqueous solutions.Slightly different from the FL mechanism of Zr-MOF,we also found an enhancement of scattered light during the binding process.This indicates that unlike Zr-MOF in which the Zr clusters act as anchor points to hold the phosphate in place, in this system the phosphate is bound to different Zr clusters on different Zr-MOCs as connecting points, linking different amounts of Zr-MOCs, which also block the LMCT effect and play a role similar to aggregation induced emission.And when the phosphate concentration exceeded beyond the linear range, a large amount of precipitation appeared in the solution, which we initially thought was a MOF or polymer formed by the MOCs being completely linked together by phosphate, but after further analysis, we found that the derivative was the phosphate replaced the ligands and cyclopentadienyl, thus forming an amorphous substance.This amorphous substance has the potential to act as a catalyst and adsorbent.

    The ZrT-1-NH2was prepared by a modified hydrothermal method [25].After centrifugation and drying, the yellow crystals obtained was observed as a cubic structure under optical and electron microscopy (Fig.S1 in Supporting information).The crystals can be redissolved in methanol, ethanol or acetonitrile solutions of arbitrary concentration and then determined by using ESI-MS (Fig.1) and FTIR (Fig.S2 in Supporting information).We observed a series of peaks with +2 to +4 charges in the ESI-MS spectra as 804[M-4Cl]4+, 1072 [M-4Cl-H]3+and 1607 [M-4Cl-2H]2+, respectively.In addition, the actual isotopic peak distributions measured from the experimental data were consistent with the simulated calculated distributions for both ZrT-1-NH2(Fig.1) and ZrT-2 (Fig.S3 in Supporting information).

    It is noteworthy that BDC-NH2as the ligand is intrinsically luminescent.Because the amino group in BDC is electron-donating,it provides the lone pair of nitrogen for the interaction withπ?-orbital of the benzene ring, and consequently enhances the FL effi-ciency of the parent BDC molecule.But the obtained ZrT-1-NH2in 1:1 methanol aqueous solution exhibits a weak FL emission peak at 437 nm while excitation at 330 nm.The results were measured by adding 50 μL of 100 μmol/L phosphate solution to different concentrations of ZrT-1-NH2solution and left for 4 h.The results were shown in Fig.S4 (Supporting information).As the concentration of ZrT-1-NH2decreases, the slope of the working curve of fluorescence enhancement gradually decreases, which indicates that its sensitivity is also decreasing, so in this work, we used 100 μmol/L as the concentration of ZrT-1-NH2.To make the assay more effi-cient, we compared four different modes of action including static,vortex, ultrasound and microwave to treat the ZrT-1-NH2solution after adding phosphate, and the results are shown in Figs.S5–S8(Supporting information).Therefore, a 90 s microwave treatment time at medium-high heat was selected for the following sensing property investigation to ensure that the fluorescence equilibrium was reached in the phosphate assay.

    To test the specificity of the ZrT-1-NH2as FL sensor, the FL response of ZrT-1-NH2solution in the presence of various anions,including SO42?, SO32?, Br?, Cl?, NO3?, was collected.As shown in Fig.2a, the FL did not change significantly after the addition of other anions at the same concentration, while the phosphate ion could enhance its FL signals by about 4.5 times, and the same phenomenon occurred in the solution of mixed ions at the same concentration.This indicates that the other anions do not interfere with the determination of phosphate ions, and the ZrT-1-NH2has excellent selective recognition function.

    Fig.2.(a) The FL response with various anions (100 μmol/L for each).(b) The FL intensity with 0–1 mmol/L [PO4]3?.(c) Linear plots of enhanced FL intensity from ZrT-1-NH2 solution as a function of phosphate concentration.(d) The photographs of FL intensity of ZrT-1-NH2 at different phosphate concentrations, excited at 365 nm.

    FL enhancement experiments with different concentrations of[PO43?] were carried out at room temperature to test the sensitivity.The FL intensity gradually increased when different concentrations of phosphate solution were added (Figs.2b and d), and there was approximately 12-fold FL enhancement when phosphate was added to 500 μmol/L (Table S1 in Supporting information).The results of the linear range test of the analytical method are shown in Fig.2c set from 5 μmol/L to 1000 μmol/L.From the results, it can be seen that there is a good linear correlation at the[PO43?] from 5 μmol/L to 500 μmol/L, and the linear equation isy=0.02024x+1.74475,R2=0.9966.The LOD of the method was calculated (3σ/sensitivity) to be 1.06 μmol/L.It can meet the primary standard for phosphate released in terms of P as stipulated in Chinese National Standard 8978–1996 and the determination range of 0.04–1.00 mg/L (1.28–32 μmol/L) in terms of P, as stipulated in Chinese Environmental Standard 670–2013, is therefore of practical application.The test results of the water quality standard solution and the actual water samples collected from Chengdu city are shown in Table S2 (Supporting information).The results are consistent with ion chromatography, which proved to be reliable.Compared with other Zr-MOFs for phosphate sensing, Zr-MOCs do not have more advantages in terms of selectivity and sensitivity(Table S3 in Supporting information).However, other aspects show great advantages: (1) All the Zr-O clusters that can undergo affinity interaction are on the surface of the MOCs, which allows the phosphate ion to bind to it very quickly, without the need for a long time to make the phosphate slowly diffuse into the interior of the MOFs and interact with the internal Zr?O clusters to achieve maximum FL enhancement.The Zr-MOC probe used in this work can be tested by microwave heating for only 90 s and could achieve good accuracy and stability.(2) ZrT is soluble in organic reagents or aqueous solution of methanol.The solubility makes MOCs more promising for surface engineering applications than insoluble MOFs.Thus, we have used it as printing ink in the next work to print test strips or other patterns using an inkjet printer for better engineering applications and sensing.

    It can be seen from Fig.2c that the FL enhancement flattens out when the phosphate concentration increases to a certain level.This phenomenon also occurred on UiO-66, and the reason is that after all the Zr sites on the surface of MOF are occupied by phosphate, the diffusion to the interior is an extremely slow process,but the interior of MOC does not have Zr sites, and the existing theory cannot explain this, so we further tested the scattered light intensity.We found that, like the FL intensity, the scattered light intensity also becomes stronger with increasing phosphate concentration, as shown in Fig.3a.This indicates that there is agglomeration of MOC in solution.To verify this mechanism, we added a high concentration of phosphate directly to the solution of MOC,and a large amount of white precipitate (denote ZrT-P) was immediately generated in the solution (Fig.S9 in Supporting information).We speculate that the mechanism is as shown in Fig.3b.That is, a phosphate ion can bind multiple 1–3 Zr-MOCs through the P ?O?Zr bond, a MOC molecule can also bind to several phosphate ions, and keep combining repeatedly until agglomerates are formed.This process, like the phosphate specific binding to the Zr site on UiO-66, also prevented the LMCT effect and thus enhanced the FL intensity.When the phosphate concentration is larger, the higher the degree of agglomeration, the more obvious the FL enhancement will be.

    To verify this mechanism, we collected mass spectrometry data of ZrT-1-NH2solutions after adding different concentrations of phosphate ions.First, the peak intensity ofm/z804 decreased dramatically, which might be caused by the binding of ZrT-1-NH2to the added phosphate (Figs.4a and b).Secondly, we observed the appearance of many clustered peaks with very small intensities, and these may be the products of what we believe to be the binding of the MOC to the phosphate.As shown in Fig.4c,upon closer inspection, we found several clustered peaks of higher intensity that were consistent with what we had speculated (Table S4 in Supporting information).Among them,m/z828 might be[M+PO4]4+or [2M+2PO4]8+,m/z960 might be [2M+3PO4]7+,m/z978 might be the summation peak of 960 with water, andm/z994 might be [3M+3PO4]10+, whose simulated spectra are shown in Fig.S10 (Supporting information).It is noteworthy that the noise of the mass spectrum is two to three orders of magnitude larger after the addition of phosphate than when it is not added, which means that more possible ionized substances appear in the solution, making it very difficult to analyze many clustered peaks with very low intensity.In addition, we speculate that the binding probability of the cage to phosphate is diverse and random, which leads to high intensity MOC ion peaks whose intensity would be randomly distributed over each binding probability, resulting in low signal values for each cluster and increasing the difficulty of our analysis.

    Fig.3.(a) The scattered intensity with 10 μmol/L and 1 mmol/L [PO4]3?.(b) Schematic depicting the phosphate induced Zr-MOCs agglomeration.

    We compared the precipitates produced by adding high concentrations of phosphate to ZrT-1 (BDC as the ligand), ZrT-1-NH2(BDC-NH2as the ligand) and ZrT-2 (1,3,5-trimesic acid as the ligand) solutions and found that they were all white precipitates,which make us confused.ZrT-1-NH2is an orthorhombic yellow crystal, and if it is combined with phosphate to form an agglomerate, the -NH2group will absorb visible light to produce color,but since ZrT-P is white then presumably its must have lost its chromophore.We surmised that the organic ligand could be removed by introduction of phosphate, so a series of characterizations of ZrT-P were performed.SEM results showed that ZrT-P has lost its orthorhombic structure and is amorphous (Fig.5a), while the XRD spectra of the three ZrT crystals with phosphate bonded to produce white precipitates are almost identical, showing that they have lost the crystalline structure of ZrT (Fig.5b).And the thermogravimetric spectra showed that ZrT-P had better thermal stability (Fig.5c).Between 30 °C and 600 °C, the mass loss was only 9.92%, of which 5.70% was lost before 100 °C, accounting for most of the mass loss, which should be caused by the incomplete drying of water.Comparing with the thermogravimetric analysis of ferrocene (Fig.S11 in Supporting information), we can see that the organic ligand will start to decompose continuously after 400 °C until only the metal oxide is left by decomposition.The FTIR results of ZrT-P show a broad peak at 3400 cm?1for theσ-P?OH absorption peak as well as the hydroxyl vibration peak of the coordinated water molecule, 1622 cm?1for the bending vibration peak of the adsorbed water molecule, 1000 cm?1for the peak appearing as theσ-P?Oabsorption peak, and 600 cm?1for the absorption peak appearing as theσ-Zr?Oabsorption peak (Fig.5d).In the whole IR spectrum, we did not observe the absorption spectrum of the organic ligand BDC-NH2, nor the cyclopentadienyl group in Zr-MOCs.Further UV–vis absorption spectrograms confirmed that the benzene ring structure was no longer present in ZrT-P (Fig.5e).ZrT-1-NH2was slightly soluble in water that we could get a weak signal in13C NMR (Fig.5f).but ZrT-P was easily soluble in water,and we still could not observe signals in13C NMR.The absence of any distinct weight loss from decomposition of ZrT-P indicates the bridging ligands were fully removed during the treatment process, further supported by CHN analysis (Table S5 in Supporting information).All the above tests indicated that not only the organic ligand was converted by phosphate in the process but also the bonding of the Zr-cyclopentadienyl is broken.A similar phenomenon occurred in the study of Lin’s group, who also obtained an amorphous derivative consisting only of Zr?O?P by immersing UiO-66 in a high concentration of sodium phosphate or phosphoric acid [21].

    We further tested the dissolution of ZrT-P in various common solvents and compared it with that of ZrT-1 and ZrT-1-NH2.It can be seen that ZrT-P is easily soluble in water but not in any other organic solvents, while Zr-MOCs can be soluble in other organic reagents (Table S6 in Supporting information).Using the property that ZrT-P is insoluble in organic solvents, we used it as a heterogeneous catalyst to catalyze the reaction of benzaldehyde with o-phenylenediamine to form 2-phenylbenzimidazole.Commonly used catalysts for this reaction include Ag2CO3, carbonloaded HfCl4, ZrOCl2, phosphoric acid, and polyphosphoric acid[26].From the results of product generation, the same weight% of ZrT-P and phosphoric acid, under the same reaction conditions, the conversion rate ofo-phenylenediamine using ZrT-P as the catalyst was 34.8% and using phosphoric acid as the catalyst was only 2.0%,indicating that the potential of ZrT-P as a Lewis acid catalyst.Another application is the adsorption of rare earth ions in aqueous solutions.ZrT-P was added to an ethanol solution containing Sm3+,Eu3+and Tb3+, placed in a shaker-oven at 150 rpm overnight.After centrifugation, the concentration of rare earth ions in the supernatant was determined by ICP-MS, and it was found that almost all rare earth ions were adsorbed (Table S7 in Supporting information), proving its potential as an adsorbent for rare earth elements or radioactive elements.

    Fig.4.The observed MS data before (a) and after (b) adding phosphate, (c) the MS data between m/z 950–1000.

    Fig.5.(a) The SEM image of ZrT-P, inset: the photography of ZrT-1-NH2, scale bar 5 μm.(b) The PXRD of derivatives from three Zr-MOCs and phosphate.(c) The TGA data of ZrT-1-NH2 and ZrT-P.(d) FTIR of ZrT-P.(e) UV absorb spectrum of ZrT-1 and ZrT-P.(f) The 13C NMR spectrum of ZrT-1-NH2 and ZrT-P.

    In conclusion, we used Zr-MOC as a FL probe for the first time to sense phosphate in water samples, which has the advantages of high selectivity, good linearity and low detection limit and can be applied to actual sample detection.We studied the interaction of Zr-MOC with phosphate for the first time by scattering spectrometry and mass spectrometry.It was found that phosphate can specifically bind to the Zr site at low concentrations, blocking the LMCT effect, and can agglomerate several cages meanwhile, resulting in enhanced FL; phosphate replaces the ligands constituting the cages at high concentrations, forming an amorphous derivative,which was characterized and analyzed for preliminary applications of catalysis and adsorption.It is believed that with further studies,the derivatives are expected to have wider applications in catalysis,metal ion adsorption,etc.

    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.

    Acknowledgment

    The authors thank the financial support from Chengdu University of Technology (No.10912-SJGG2021-06843).

    Supplementary materials

    Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2021.12.035.

    成人二区视频| 国产精品国产三级国产专区5o| 国产成人精品福利久久| 亚洲av欧美aⅴ国产| 极品人妻少妇av视频| 亚洲国产毛片av蜜桃av| 日日爽夜夜爽网站| 免费av中文字幕在线| 午夜福利视频在线观看免费| 一区二区三区精品91| 日韩电影二区| 最近中文字幕高清免费大全6| 中国国产av一级| freevideosex欧美| 巨乳人妻的诱惑在线观看| 亚洲国产欧美网| 成人毛片60女人毛片免费| 伊人久久国产一区二区| 一区二区三区四区激情视频| 少妇人妻 视频| 免费观看av网站的网址| 国产日韩欧美在线精品| 秋霞伦理黄片| 精品人妻熟女毛片av久久网站| 老汉色av国产亚洲站长工具| 肉色欧美久久久久久久蜜桃| 国产黄色免费在线视频| 精品一区二区免费观看| 欧美另类一区| 中文字幕av电影在线播放| 成人漫画全彩无遮挡| 在线观看美女被高潮喷水网站| 高清不卡的av网站| av女优亚洲男人天堂| 韩国高清视频一区二区三区| av在线老鸭窝| 中文字幕人妻丝袜一区二区 | 久久 成人 亚洲| 性色avwww在线观看| 夜夜骑夜夜射夜夜干| 亚洲国产色片| 久久久久久久国产电影| 午夜福利乱码中文字幕| 女人久久www免费人成看片| 欧美最新免费一区二区三区| 一区二区三区精品91| 国产亚洲欧美精品永久| 精品少妇内射三级| 麻豆乱淫一区二区| 国产成人精品一,二区| 男人添女人高潮全过程视频| 久久久久精品人妻al黑| 日本-黄色视频高清免费观看| 午夜av观看不卡| 久久久久久伊人网av| 欧美国产精品一级二级三级| 美国免费a级毛片| 人妻少妇偷人精品九色| 亚洲精品国产av蜜桃| 国产精品麻豆人妻色哟哟久久| 美女午夜性视频免费| 巨乳人妻的诱惑在线观看| 精品一品国产午夜福利视频| 日日撸夜夜添| 在线免费观看不下载黄p国产| av国产精品久久久久影院| 七月丁香在线播放| 久久精品亚洲av国产电影网| 亚洲经典国产精华液单| 国产亚洲av片在线观看秒播厂| 99热网站在线观看| 欧美精品一区二区大全| 国产伦理片在线播放av一区| 熟妇人妻不卡中文字幕| 一级黄片播放器| 久久韩国三级中文字幕| 一区二区三区精品91| 国产男女超爽视频在线观看| 欧美在线黄色| 欧美成人精品欧美一级黄| 2021少妇久久久久久久久久久| 观看美女的网站| av福利片在线| 成人免费观看视频高清| 午夜福利视频在线观看免费| 久久人人爽人人片av| 国产精品女同一区二区软件| 亚洲av国产av综合av卡| 国产精品香港三级国产av潘金莲 | 美女中出高潮动态图| 欧美日韩亚洲国产一区二区在线观看 | 精品视频人人做人人爽| 一区二区日韩欧美中文字幕| 久久久久久人妻| 极品少妇高潮喷水抽搐| 国产成人精品一,二区| 久久精品国产a三级三级三级| av在线app专区| 欧美成人午夜免费资源| 十八禁高潮呻吟视频| av在线老鸭窝| 国产精品麻豆人妻色哟哟久久| 欧美在线黄色| 国产xxxxx性猛交| 亚洲国产精品国产精品| 在线免费观看不下载黄p国产| 亚洲国产色片| 男人爽女人下面视频在线观看| 亚洲成人手机| 国产成人免费无遮挡视频| 日韩成人av中文字幕在线观看| 我的亚洲天堂| 久久影院123| www.熟女人妻精品国产| 欧美少妇被猛烈插入视频| 亚洲国产欧美在线一区| 多毛熟女@视频| 中国国产av一级| 国产精品女同一区二区软件| 国产激情久久老熟女| 中文精品一卡2卡3卡4更新| 自拍欧美九色日韩亚洲蝌蚪91| 久久久久国产一级毛片高清牌| 在线观看三级黄色| 欧美日韩视频精品一区| 蜜桃在线观看..| 999精品在线视频| 9热在线视频观看99| 卡戴珊不雅视频在线播放| 啦啦啦中文免费视频观看日本| 久久综合国产亚洲精品| 国产一区二区 视频在线| 搡老乐熟女国产| av天堂久久9| 两个人看的免费小视频| 久久久久久久久免费视频了| 丰满乱子伦码专区| 十分钟在线观看高清视频www| 亚洲欧美精品自产自拍| 国产毛片在线视频| 亚洲欧美色中文字幕在线| 精品亚洲成国产av| 久久精品国产亚洲av天美| 999久久久国产精品视频| 国产欧美日韩一区二区三区在线| 一区二区三区激情视频| 欧美 亚洲 国产 日韩一| 亚洲国产最新在线播放| 丰满乱子伦码专区| √禁漫天堂资源中文www| 啦啦啦在线观看免费高清www| 美女国产视频在线观看| 一级毛片 在线播放| 最近最新中文字幕免费大全7| 美女国产视频在线观看| 国产男人的电影天堂91| 最新的欧美精品一区二区| av在线观看视频网站免费| 母亲3免费完整高清在线观看 | 女的被弄到高潮叫床怎么办| 99久国产av精品国产电影| 成年女人在线观看亚洲视频| 黄色 视频免费看| 成年av动漫网址| 亚洲国产精品国产精品| 久久人人97超碰香蕉20202| 亚洲av免费高清在线观看| 国产精品熟女久久久久浪| 亚洲精品av麻豆狂野| 美女福利国产在线| 成人18禁高潮啪啪吃奶动态图| 久久人人爽av亚洲精品天堂| 丝袜人妻中文字幕| 永久免费av网站大全| 亚洲av电影在线进入| 伊人久久大香线蕉亚洲五| 男男h啪啪无遮挡| 午夜久久久在线观看| av免费观看日本| 国产一区二区激情短视频 | 老鸭窝网址在线观看| 亚洲精品久久成人aⅴ小说| 国产免费又黄又爽又色| 如何舔出高潮| 26uuu在线亚洲综合色| 亚洲成人av在线免费| 91成人精品电影| 高清欧美精品videossex| 日本av手机在线免费观看| 有码 亚洲区| 自拍欧美九色日韩亚洲蝌蚪91| 日韩大片免费观看网站| av网站在线播放免费| 18在线观看网站| 美女脱内裤让男人舔精品视频| 国产成人一区二区在线| 97在线人人人人妻| 久热久热在线精品观看| 精品亚洲成a人片在线观看| 极品少妇高潮喷水抽搐| 丁香六月天网| 久久毛片免费看一区二区三区| 亚洲精华国产精华液的使用体验| 99re6热这里在线精品视频| 国产欧美亚洲国产| 美女午夜性视频免费| 亚洲欧美日韩另类电影网站| 美女福利国产在线| 国精品久久久久久国模美| 国产成人av激情在线播放| 在线观看三级黄色| 精品一区二区免费观看| 日韩人妻精品一区2区三区| 亚洲成av片中文字幕在线观看 | 热re99久久国产66热| 青青草视频在线视频观看| 亚洲天堂av无毛| 美女中出高潮动态图| 中文字幕亚洲精品专区| 国产免费一区二区三区四区乱码| 国产亚洲最大av| 精品国产乱码久久久久久小说| 天天躁夜夜躁狠狠久久av| 肉色欧美久久久久久久蜜桃| 久久女婷五月综合色啪小说| 国产一区二区三区综合在线观看| 高清在线视频一区二区三区| 亚洲国产欧美日韩在线播放| 一本大道久久a久久精品| 国产免费一区二区三区四区乱码| 日韩中文字幕视频在线看片| 国产一区二区三区av在线| 国产一区二区三区av在线| 亚洲精品视频女| 大香蕉久久网| 国产精品国产av在线观看| 日本欧美视频一区| 天天躁日日躁夜夜躁夜夜| 久久久久久久久免费视频了| 制服人妻中文乱码| 美女国产视频在线观看| 亚洲精品视频女| 亚洲精品aⅴ在线观看| 国产精品香港三级国产av潘金莲 | 永久网站在线| 午夜免费男女啪啪视频观看| 99久久精品国产国产毛片| 亚洲欧美一区二区三区黑人 | 免费高清在线观看视频在线观看| 国产一区二区激情短视频 | 亚洲欧美精品自产自拍| 制服诱惑二区| 熟女少妇亚洲综合色aaa.| 国产精品嫩草影院av在线观看| 黑人巨大精品欧美一区二区蜜桃| 欧美在线黄色| 久久久久久久久久人人人人人人| 国产女主播在线喷水免费视频网站| 成人黄色视频免费在线看| 大码成人一级视频| 91精品伊人久久大香线蕉| 日韩中文字幕欧美一区二区 | 国产极品粉嫩免费观看在线| 一边亲一边摸免费视频| 国产精品久久久久久av不卡| 亚洲精品一区蜜桃| 久久女婷五月综合色啪小说| 日本vs欧美在线观看视频| 亚洲精品国产av成人精品| 国产又爽黄色视频| 成年美女黄网站色视频大全免费| 国产精品人妻久久久影院| 国语对白做爰xxxⅹ性视频网站| 亚洲图色成人| 国产熟女欧美一区二区| 丰满乱子伦码专区| 亚洲欧美日韩另类电影网站| 国产不卡av网站在线观看| 国产 一区精品| 日韩成人av中文字幕在线观看| 国产欧美日韩一区二区三区在线| 国产白丝娇喘喷水9色精品| 日韩不卡一区二区三区视频在线| 国产免费视频播放在线视频| 高清在线视频一区二区三区| 免费观看av网站的网址| 久久久国产一区二区| 人妻系列 视频| 国产午夜精品一二区理论片| 黄片无遮挡物在线观看| 国产日韩一区二区三区精品不卡| 欧美日韩av久久| 亚洲三级黄色毛片| 交换朋友夫妻互换小说| 男女国产视频网站| 韩国高清视频一区二区三区| 国产一区二区三区综合在线观看| 免费播放大片免费观看视频在线观看| 亚洲婷婷狠狠爱综合网| 亚洲国产毛片av蜜桃av| 人成视频在线观看免费观看| 女人精品久久久久毛片| 成人亚洲欧美一区二区av| 欧美日韩一级在线毛片| 久久韩国三级中文字幕| 伊人久久大香线蕉亚洲五| 老司机影院毛片| 久久久久精品久久久久真实原创| 中国国产av一级| 亚洲精品第二区| 国产淫语在线视频| 麻豆av在线久日| 国产片内射在线| 久久久久久免费高清国产稀缺| 熟女av电影| 亚洲成国产人片在线观看| 欧美成人精品欧美一级黄| 国产极品天堂在线| 在线免费观看不下载黄p国产| 免费观看av网站的网址| 一本久久精品| 国产男女超爽视频在线观看| 王馨瑶露胸无遮挡在线观看| 伦理电影大哥的女人| 两个人看的免费小视频| 熟女av电影| 亚洲欧洲日产国产| 巨乳人妻的诱惑在线观看| 日本vs欧美在线观看视频| 女人被躁到高潮嗷嗷叫费观| 观看av在线不卡| 天堂俺去俺来也www色官网| 电影成人av| 国产精品嫩草影院av在线观看| 亚洲成人av在线免费| 啦啦啦视频在线资源免费观看| 精品人妻在线不人妻| 制服诱惑二区| 欧美日韩亚洲国产一区二区在线观看 | 久久影院123| 亚洲国产欧美日韩在线播放| 亚洲成人av在线免费| www.精华液| tube8黄色片| 日韩一卡2卡3卡4卡2021年| 欧美 日韩 精品 国产| 国产黄频视频在线观看| 亚洲精品在线美女| 欧美日韩成人在线一区二区| 久久人人爽人人片av| 电影成人av| 中文乱码字字幕精品一区二区三区| 香蕉丝袜av| 嫩草影院入口| 国产一区二区三区综合在线观看| 天美传媒精品一区二区| 午夜免费男女啪啪视频观看| 成人影院久久| 国产毛片在线视频| 黑人欧美特级aaaaaa片| 免费在线观看完整版高清| 国产人伦9x9x在线观看 | 久久影院123| 国产av一区二区精品久久| 国产男女内射视频| 精品一品国产午夜福利视频| 欧美少妇被猛烈插入视频| 精品视频人人做人人爽| 国产精品欧美亚洲77777| 巨乳人妻的诱惑在线观看| 少妇的丰满在线观看| 日本91视频免费播放| 女人精品久久久久毛片| 一级爰片在线观看| 国产亚洲欧美精品永久| 成人午夜精彩视频在线观看| 欧美少妇被猛烈插入视频| 一区二区日韩欧美中文字幕| 国产视频首页在线观看| 亚洲国产精品999| 成人漫画全彩无遮挡| 亚洲第一青青草原| 黄色怎么调成土黄色| 欧美黄色片欧美黄色片| 青青草视频在线视频观看| 一本一本久久a久久精品综合妖精 国产伦在线观看视频一区 | 国产爽快片一区二区三区| 午夜av观看不卡| 婷婷色av中文字幕| 久久精品国产自在天天线| 18禁动态无遮挡网站| 99香蕉大伊视频| 超碰97精品在线观看| 日本av免费视频播放| 国产精品久久久久久精品古装| 大香蕉久久成人网| 飞空精品影院首页| 日本午夜av视频| 国产一级毛片在线| 日韩不卡一区二区三区视频在线| av在线app专区| 成人国产av品久久久| 伊人久久大香线蕉亚洲五| 黄片无遮挡物在线观看| 在线亚洲精品国产二区图片欧美| 国产国语露脸激情在线看| 18禁观看日本| 一级毛片 在线播放| av在线老鸭窝| 亚洲欧洲日产国产| 黄片小视频在线播放| 国产成人av激情在线播放| 不卡视频在线观看欧美| 亚洲,一卡二卡三卡| www.av在线官网国产| 国产精品久久久久久av不卡| 你懂的网址亚洲精品在线观看| 超碰成人久久| 中文天堂在线官网| 青春草国产在线视频| 午夜av观看不卡| 中文字幕制服av| 国产麻豆69| 日日啪夜夜爽| 又粗又硬又长又爽又黄的视频| 欧美在线黄色| 国产人伦9x9x在线观看 | 好男人视频免费观看在线| 夫妻性生交免费视频一级片| 又黄又粗又硬又大视频| 国产女主播在线喷水免费视频网站| 水蜜桃什么品种好| 欧美亚洲 丝袜 人妻 在线| 亚洲av综合色区一区| 亚洲天堂av无毛| 久久久久久人妻| 色婷婷av一区二区三区视频| 一级爰片在线观看| 精品一区在线观看国产| 国产毛片在线视频| 午夜福利视频精品| 永久网站在线| 99热全是精品| 波多野结衣一区麻豆| 亚洲av综合色区一区| 国产欧美日韩综合在线一区二区| 老熟女久久久| 啦啦啦在线观看免费高清www| 两个人免费观看高清视频| 久久热在线av| 国产成人精品福利久久| 我要看黄色一级片免费的| 成人毛片a级毛片在线播放| 午夜激情av网站| 国产黄色免费在线视频| 中文字幕制服av| av片东京热男人的天堂| 在线观看免费视频网站a站| 国产日韩一区二区三区精品不卡| 五月开心婷婷网| av国产久精品久网站免费入址| 少妇的丰满在线观看| 巨乳人妻的诱惑在线观看| 丰满乱子伦码专区| 欧美日本中文国产一区发布| 啦啦啦视频在线资源免费观看| 人体艺术视频欧美日本| 777久久人妻少妇嫩草av网站| 日韩一本色道免费dvd| 美女国产高潮福利片在线看| 91精品三级在线观看| 美女高潮到喷水免费观看| 日韩中文字幕视频在线看片| 三上悠亚av全集在线观看| 亚洲人成电影观看| 一二三四在线观看免费中文在| 制服丝袜香蕉在线| 国产1区2区3区精品| 一本一本久久a久久精品综合妖精 国产伦在线观看视频一区 | 国产精品免费大片| 久久狼人影院| 国产男人的电影天堂91| 国产淫语在线视频| 2018国产大陆天天弄谢| 久久国产精品男人的天堂亚洲| 可以免费在线观看a视频的电影网站 | 亚洲精品成人av观看孕妇| 国产成人精品无人区| 欧美日韩精品网址| 亚洲av中文av极速乱| 秋霞在线观看毛片| 亚洲人成电影观看| 国产无遮挡羞羞视频在线观看| 中文欧美无线码| 亚洲av综合色区一区| 国产一区二区三区av在线| 999精品在线视频| 91aial.com中文字幕在线观看| 女人被躁到高潮嗷嗷叫费观| av福利片在线| 九九爱精品视频在线观看| 一区二区av电影网| 丁香六月天网| 精品午夜福利在线看| 在线观看免费视频网站a站| 亚洲精品国产色婷婷电影| 蜜桃在线观看..| 在线观看美女被高潮喷水网站| 国产欧美亚洲国产| 国产精品女同一区二区软件| 日韩在线高清观看一区二区三区| 午夜激情久久久久久久| 亚洲少妇的诱惑av| 国产一区二区三区av在线| 最近2019中文字幕mv第一页| 高清黄色对白视频在线免费看| 超碰成人久久| 叶爱在线成人免费视频播放| 国产精品久久久久久av不卡| 久久久久久久久久久免费av| 最近中文字幕高清免费大全6| 在线精品无人区一区二区三| 人人澡人人妻人| a级片在线免费高清观看视频| 黑人猛操日本美女一级片| 桃花免费在线播放| 九九爱精品视频在线观看| 美女大奶头黄色视频| 日韩伦理黄色片| av卡一久久| 精品国产露脸久久av麻豆| 午夜日韩欧美国产| 老汉色av国产亚洲站长工具| xxxhd国产人妻xxx| 欧美激情极品国产一区二区三区| 一二三四中文在线观看免费高清| 免费大片黄手机在线观看| 国产精品女同一区二区软件| 久久久久精品人妻al黑| 热re99久久国产66热| 在线天堂最新版资源| av电影中文网址| 亚洲av日韩在线播放| 免费日韩欧美在线观看| a级毛片在线看网站| 性色av一级| 日韩中字成人| 黑人巨大精品欧美一区二区蜜桃| 99热网站在线观看| 乱人伦中国视频| 日本wwww免费看| 欧美精品高潮呻吟av久久| 大片电影免费在线观看免费| 久久这里有精品视频免费| 青春草亚洲视频在线观看| 国产探花极品一区二区| 91精品国产国语对白视频| 熟女电影av网| 下体分泌物呈黄色| 男女边摸边吃奶| 久久精品夜色国产| 香蕉丝袜av| 久久国产亚洲av麻豆专区| 久久亚洲国产成人精品v| 青青草视频在线视频观看| 女性生殖器流出的白浆| 91精品伊人久久大香线蕉| 久久久久国产网址| 国产精品欧美亚洲77777| 丝瓜视频免费看黄片| 视频区图区小说| 欧美亚洲日本最大视频资源| 男女下面插进去视频免费观看| 日本欧美国产在线视频| 精品福利永久在线观看| 亚洲欧美日韩另类电影网站| 国产黄色免费在线视频| 亚洲av综合色区一区| 日韩伦理黄色片| 国产日韩欧美亚洲二区| 精品久久蜜臀av无| 两个人免费观看高清视频| 亚洲av电影在线观看一区二区三区| 亚洲久久久国产精品| 国产免费视频播放在线视频| 人体艺术视频欧美日本| 老司机影院成人| 精品人妻偷拍中文字幕| 啦啦啦啦在线视频资源| 免费观看a级毛片全部| 黑人巨大精品欧美一区二区蜜桃| 中国三级夫妇交换| 亚洲国产看品久久| 在线观看国产h片| 欧美激情极品国产一区二区三区| 精品国产国语对白av| 永久网站在线| 中文字幕制服av| www.熟女人妻精品国产| 国产高清不卡午夜福利| 日韩一区二区三区影片| 久久久久国产一级毛片高清牌| 九草在线视频观看| 九色亚洲精品在线播放| 精品国产乱码久久久久久小说| 少妇被粗大的猛进出69影院| 日韩免费高清中文字幕av| av免费观看日本| 80岁老熟妇乱子伦牲交| 国产在视频线精品| 欧美日韩精品成人综合77777| av视频免费观看在线观看| 一本久久精品| 亚洲天堂av无毛| 赤兔流量卡办理|