Clickable Periodic Mesoporous Organosilica Monolith for Highly

Subscriber access provided by ORTA DOGU TEKNIK UNIVERSITESI KUTUPHANESI

Letter

Clickable periodic mesoporous organosilica monolith for highly efficient capillary chromatographic separation Ci Wu, Yu Liang, Kaiguang Yang, Yi Min, Zhen Liang, Lihua Zhang, and YuKui Zhang Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.5b04641 • Publication Date (Web): 11 Jan 2016 Downloaded from http://pubs.acs.org on January 13, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Analytical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Analytical Chemistry

Clickable periodic mesoporous organosilica monolith for highly efficient capillary chromatographic separation Ci Wu‡ab, Yu Liang‡a, KaiguangYanga, Yi Minab, Zhen Lianga, Lihua Zhang*a, Yukui Zhanga a Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China). b University of the Chinese Academy of Sciences, Beijing, 100049 (China) ‡These authors contributed equally. ABSTRACT: A novel clickable periodic mesoporous organosilica monolith with the surface area up to 1707 m2 g−1 was in-situ synthesized in the capillary by the one-step condensation of the organobridged-bonded alkoxysilane precursorbis(triethoxysilyl)ethylene. With Si-C bonds in the skeleton, the monolith possesses excellent chemical and mechanical stability. With vinyl groups highly loaded and homogeneously distributed throughout the structure, the monolith can be readily functionalized with functional groups by effective thiol-ene “click” chemistry reaction. Herein, with “click” modification of C18, the obtained monolith was successfully applied for capillary liquid chromatography separation of small molecules and proteins. The column efficiency could reach 148000 N/m, higher than most reported hybrid monoliths. Moreover, intact proteins could be separated well with good reproducibility, even after the monolithic column was exposed by basic mobile phase (pH 10.0) overnight, demonstrating the great promising of such monolith for capillary chromatography separation.

With the advantages of high permeability and fast mass transfer, as well as a good scaling capability, to fill various moulds ranging from micrometre to centimetre, monoliths have attracted the attention of researchers in various fields1-6, especially in the field of separation science7-9. Ideal monolithic materials should have several important properties10. First, the surface area and the loading amount of functional groups should be as large as possible to provide a sufficient number of active sites. Second, excellent chemical and mechanical stability is indispensable to ensure good practicability. Third, an ease of preparation and tailorability are also needed for widespread applications. Therefore, organic-inorganic hybrid silica monoliths11-12 have drawn much attention due to their improved chemical stability over a wide pH range compared with silica monoliths as well as their relatively high surface area (typically approximately 300 m2·g-1) compared with polymer monoliths. Traditionally, hybrid monoliths are mainly synthesized by the “sol-gel” condensation of alkoxyorganosilanes with tetraalkoxysilanes13-16. However, being limited by the disrupting effect of increased alkoxyorganosilanes on the degree of mesoscopic order of the products, the organosilane concentration in the reaction mixture typically does not exceed 40 mol%, resulting in a low density of functional groups17. Recently, periodic mesoporous organosilicas (PMOs) based on organobridged-bonded alkoxysilane precursors ((R'O)3Si– R–Si(OR')3) with self-oriented organic functional groups (R) have attracted a lot of attention in hybrid silica material synthesis18-23, which usually have a high surface area (ca. 500–900 m2· g−1) and provide the possibility of introducing high density of functional groups. Ethyl-bridged alkoxysilanes24 and phenyl-bridged alkoxysilanes25-26 have been used to prepare hybrid silica monoliths with chemically stable Si-R-Si bonds in

the framework via the hydrothermal method and a diolmodified strategy, respectively; however, the difficulties in further modification via the inactive phenyl or ethyl group and the extremely complicated fabrication procedures prevent such monoliths from further applications, especially in the fields of microscale analysis. To the best of knowledge, the PMO monoliths haven’t been prepared in the capillary and used for nano-scale liquid chromatography, which plays significant roles in the analysis of trace samples. In this work, a novel type of hybrid monolith with vinyl groups homogeneously distributed throughout the framework was synthesized facilely in the capillary by the one-step “solgel” condensation of the ethylene-bridged alkoxysilane precursor. With an extremely large surface area and highly loaded vinyl groups in the skeleton, this PMO monolith could be further modified with C18 groups by an effective thiol-ene “click” chemistry reaction for high efficient nano-reversed phase liquid chromatography. As shown in Scheme 1, the ethylene-bridged hybrid silica monolith was prepared via the condensation of bis(triethoxysilyl)ethylene ((C2H5O)3Si–CH2=CH2– Si(OC2H5)3), BTSEY) in the presence of a double-templating system, composed of hexadecyltrimethylammonium chloride (CTAC) and F127 (non-ionic block copolymer surfactant, poly(propylene glycol)-block-poly(ethylene glycol)-blockpoly(propylene glycol), average Mn ~12600), with triethylamine (TEA) as the basic catalyst. Methanol, possessing good solubility for both the bridged-silane precursor and the templates, was used as the solvent to form homogeneous prepolymerization solution, beneficial for the in-situ preparation of monoliths, regardless of whether the synthesis occurred in micrometre capillaries or centimetre tubes (Figures 1a and 1b).

ACS Paragon Plus Environment

Analytical Chemistry

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Scheme 1. Preparation of BTSEY monoliths and functionalization via thiol-ene click chemistry, R: functional groups C18H37.

Page 2 of 6

atoms, respectively. The absence of a resonance from the Q species (Qn: Si(OSi)n(OH)4-n, n=2–4) confirms that no Si-C bond cleavage occurred during either the synthesis or the surfactant extraction. Therefore, every Si atom in the BTSEY monolith is bonded to carbon. This Si-C bond in the framework provides an improved hydrolytic stability over that of the Si-O-Si linkage that exists in hybrid monoliths prepared with traditional precursors28, 29, which might improve separation reproducibility. The13C CP MAS NMR spectrum (Figure 2b) displays a strong resonance at 146 ppm, which are attributed to the ethylene carbon atoms and confirms that the vinyl bonds are abundant in the framework of the monolith.

Figure 1. Characterization of the BTSEY monolith. a) A SEM image of the BTSEY monolith in a capillary (i.d. 100 µm) 900×, b) photograph of the bulk BTSEY monolith, c) an SEM image of the BTSEY monolith 5000×, and d) the pore size distribution.

The morphology of the monolith prepared in the capillary with a 100 µm ID (inner diameter) was characterized by SEM. The monolithic bed with a continuously rough skeleton is well attached to the inner wall of the capillary. As shown in Figure 1c, the clearly large through-pores ensure good permeability for flow-through. With nitrogen adsorption/desorption analysis, the BET specific surface area of the monolith reaches 1707 m2·g-1 with a pore volume of 2.328 cm3·g-1. Deductively, such a high surface area originated from the abundant micropores (791 m2·g1 ) and mesopores (916 m2·g-1) exhibited by this novel monolith. Furthermore, this surface area is much larger than the reported phenyl- or ethyl-bridged hybrid monoliths (less than 900 m2·g-1) and traditional hybrid monoliths (approximately 300 m2·g-1) 24, 25, 27, which might improve separation efficiency. The pore sizes of the monolithic material are of a narrow bimodal distribution, with a maximum micropore at 1.2 nm and mesopore mainly distributed at 3–5 nm. Such a hierarchical porous structure may be attributed to the doubletemplating system present during condensation. The formation of through-macropores was controlled via the non-ionic surfactant block copolymer, F127, while the micro- and mesopores were derived from CTAC. The use of BTSEY as the only precursor offers a framework that is 100% loaded with ethylene, which was further confirmed with NMR. The 29Si MAS NMR spectrum of the monolith displays three peaks that are located at -65, -75 and 83 ppm (Figure 2a) and should be assigned to T1 [CSi(OSi)(OH)2], T2 [CSi(OSi)2(OH)] and T3 [(CSi(OSi)3] Si

Figure 2. a) 29Si MAS NMR spectra and b) 13C CP MAS NMR spectra of BTSEY monolith. The asterisks denote spinning sidebands. The signal at 49 ppm reflects the presence of methoxy groups, which originated from the solvent exchange with methanol during the surfactant extraction process.

The mechanical and chemical stability of the monolithic material is important for the separation of analytes with various properties. Herein, the relationship between the back pressure and the flow rate of the capillary monolithic column, with an inner diameter of 100 µm, was evaluated with mobile phases at different pH. As shown in Figure S1, the back pressure increased linearly with the flow rate in both acidic (pH 2.1) and alkaline (pH 10.0) solutions. Moreover, the monolithic column could bear a maximum pressure of up to more than 25 MPa. These results indicate the excellent mechanical and chemical stability of our prepared ethylene-bridged hybrid silica monolith. The versatility of our prepared ethylene-bridged hybrid silica monoliths is of great significance to broaden the applications in different fields. With BTSEY as the single precursor, vinyl groups are readily available in the skeleton of the monolith, so that various modifications can easily be achieved by thiol-ene “click” chemistry30, with high reaction efficiency under mild conditions.

ACS Paragon Plus Environment

Page 3 of 6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Analytical Chemistry

Table 1. Elemental analysis for hybrid silica monolith functionalized with C18 groups. Sample

C%

H%

N%

S%

BTSEY monolith

17.25

4.04

˂0.3

˂0.5

C18@BTSEY monolith

54.73

9.21

˂0.3

6.55

Herein, the synthesized ethylene-bridged hybrid silica monolith underwent facile modification with octadecanethiol (C18-SH). After modification with C18 functional groups, the contact angle of water on the monolith (Figure S2a) changed from nearly zero to 137°, demonstrating the successful modification by the hydrophobic molecule. In addition, via thermogravimetric analysis (TGA) (Figure S2b), the overall percentage of organic matter in the materials before and after modification was 14.6% and 27% respectively, and such differential organic matter weight percentage also confirmed the introduction of C18 groups. The percentage of carbon was determined to be 54.73% (Table 1) through elemental analysis. The high loading of vinyl groups within the monolith contributed to this value, and the carbon content of the decorated hybrid material was much higher than traditionally bonded silica materials (carbon content 20–34.3%)31, 32. The surface coverage of C18 groups throughout the material was calculated to be 2.03 µmol·m-2, which is the critical ligand density for the highresolution separation of analysts33. Owning to the hierarchical structure of the hybrid monolith, the prepared C18-functionalized capillary monolithic column was further used for the nano-reversed phase liquid chromatography-based separation of not only small molecules but also biomolecules. Five alkylbenzenes were baseline separated with good peak shapes using ACN/H2O (50/50, v/v) as mobile phase (Figure 3a). The hydrophobicity of a HPLC stationary phase can be conveniently characterized by the methylene selectivity, αCH2, which is calculated from the equation: lnk=n lnαCH2+ lnβ, where n is the number of saturated carbon atoms in the alkyl chain of alkylbenzenes, and β is the retention factor of benzene34, 35. As shown in Figure 3b, the plots of logarithmic retention factors of alkylbenzenes versus the number of saturated carbon atoms in the alkyl chain of alkylbenzenes were all linear (R>0.998), giving αCH2 values for the hybrid monolith of 1.55, 1.43, 1.34, 1.28 and 1.23 at 35%, 40%, 45%, 50% and 55% ACN mobile phase concentration, respectively, indicating the good hydrophobicity of our monolith. Additionally, as shown in Figure S3, the relationship between the linear velocity and plate height of alkylbenzenes on such column was investigated, with the highest column efficiency of 148000 achieved. As shown in Figure 3c, the base-line separation of four proteins was achieved with good peak shapes, which was maintained even after washed by basic mobile phase (pH 10) overnight (Figure 3d), demonstrating the excellent chemical rigidity of the material. Additionally, the RSDs of the protein retention factors from run-to-run and column-to-column were in the range of 0.51 to 1.38% and 1.44 to 4.19% (n=4), respectively, which demonstrates good operation and preparation reproducibility. Moreover, such a monolith was also successfully applied to the separation of proteins in complex real sample (Figure 4), indicating its excellent potential for bioanalysis.

Figure 3. (a) Chromatography of alkylbenzenes separated by C18@BTSEY monolithic column (i.d.100 µm, 25 cm). Separation conditions: mobile phase, ACN/H2O (50/50, v/v); flow rate: 344 nL/min, detection wavelength, 214 nm.; (b) the effect of the number of saturated carbon atoms in the alkyl chain on logarithmic retention factors of alkylbenzenes at different percentages of ACN on hybrid monoliths ; Chromatograms of four-protein mixture separation (c) before and (d) after the C18@BTSEY monolithic column (i.d.100 µm, 25 cm) washed with about 200 µL basic mobile phase (pH 10) overnight at the flow rate of 300 nL/min. Separation conditions for (c) and (d): 2 % mobile phase B to 80 % mobile phase B in 40 min (A, 0.1 % TFA in water, B, 0.1 % TFA in ACN, v/v), flow rate: 500 nL/min, detection wavelength, 214 nm.

Figure 4. The Chromatogram of proteins in Hela cell lysates separated by a C18@BTSEY monolithic column (i.d.100 µm, 20 cm). Separation conditions: 2 % mobile phase B to 80 % mobile phase B in 80 min; flow rate: 500 nL/min, detection wavelength, 214 nm.

In conclusion, a novel PMO monolith based on an ethylene-bridged alkoxysilane precursor was prepared with large surface area, great rigidity and an abundance of vinyl groups within the framework. Such hierarchical monolith was synthesized in-situ in capillary, decorating with C18 groups, and applied as excellent reversed stationary phase for high efficient nanoRPLC separation of not only small molecules, but also complex protein samples. By using highly efficient thiolene “click” chemistry, such monolithic materials could be further facilely functionalized with different functional groups for various separation modes. It is expected that PMO monoliths have great potential to broaden the applications of chromatography.

ACS Paragon Plus Environment

Analytical Chemistry

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 6

also thank Song Shi from Dalian Institute of Chemical Physics for valuable advice and fruitful discussion.

Experimental Sections Synthesis of ethylene-bridged hybrid silica monolith

REFERENCES To expose the maximum number of silanol groups at the inner wall, the capillary was first flushed with 1 M HCl for 2 h, washed by water for 30 min, treated by 10% HF for 3 h at 35 °C, washed by water for 30 min, rinsed with 1 M NaOH for 2 h, and flushed with water and methanol. After the capillary was dried at 120 °C under a nitrogen atmosphere overnight, the ethylene-bridged hybrid silica monolithic column (BTSEY monolith) was prepared by a one-step basic catalytic sol-gel process. The reaction solution was composed of 10 mg of F127, 32 mg of CTAC, 120 µL of BTSEY, 160 µL of methanol, 20 µL of water, and 5 µL of TEA. The pre-treated capillary was filled with the mixture using a syringe. With both ends sealed by rubber, the capillary was incubated at 40 °C for 12 h for the sol-gel reaction. Finally, the obtained column was washed with methanol to remove the templates and unreacted reagents. The bulk BTSEY monolith was synthesized in a regular empty HPLC column (i.d.4.6 mm, 5 cm) and then moved out of the column and cut into pieces. The pieces were washed with methanol using a Soxhlet extractor for 72 h, and dried at 50 °C for 24 h for further characterization. Thiol-ene “click” modification of ethylene-bridged hybrid silica monolith For the monolithic material modifications, the reaction solution, composed of 0.1 M C18-SH and 3 mg/mL AIBN (dissolved in ethanol), was first pumped through the poly (BTSEY) monolith at room temperature for 30 min. The column was then sealed at both ends, and the reaction was carried out in a water bath at 65 °C for 4 h. This procedure was repeated twice to achieve maximum modification. Finally, the obtained C18modified columns were sequentially washed with ethanol and water.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Materials & Apparatus, relationships between the flow rate and the back pressure of the BTSEY monolith, contact angle and thermal gravimetric analysis (TGA) of BTSEY monolith, Evaluation of the column efficiency of the monolith. (PDF)

AUTHOR INFORMATION Corresponding Author *Phone: +86-411-84379720. Fax: +86-411-84379720. E-mail: [email protected].

ACKNOWLEDGEMENT The authors are grateful for the financial support from National Basic Research Program of China (2012CB910601), National Natural Science Foundation (21190043, 21205115, 21235005, 21575139) and National Key Scientific Instrument and Equipment Development Project (2012YQ120044-8). We

1 A. El Kadib, R. Chimenton, A. Sachse, F. Fajula, A. Galarneau., B. Coq, Angew. Chem. Int. Ed. 2009, 48, 4969. 2 G. Hayase1, K. Kanamori1, G. Hasegawa, A. Maeno, H. Kaji, K. Nakanish, Angew. Chem. Int. Ed. 2013, 52, 10788. 3 H. Zhong, G. Zhu, J. Yang, P. Wang and Q. Yang, Microporous Mesoporous Mater. 2007, 100, 259. 4 I. Nischang, O. Brüggemann, I. Teasdale, Angew. Chem. Int. Ed. 2011, 50, 4592. 5 Y. Zhou, M. M. Wan, L. Gao, N. Lin, W. G. Lin, J. H. Zhu, J. Mater. Chem. B 2013, 1, 1738. 6 H. Li, D. Zhang, P. Maitarad, L. Shi, R. Gao, J. Zhang, W. Cao, Chem. Commun. 2012, 48, 10645. 7 N. Tanaka, D. V. McCalley, Anal. Chem. 2015, doi: 10.1021/acs.analchem.5b04093 . 8 A. Marechal, F. Jarrosson, J. Randon, V. Dugas, C. Demesmay, J Chromatogr A. 2015, 1406, 109. 9 Laaniste A, Marechal A, El-Debs R, Randon J, Dugas V, Demesmay, C, J. Chromatogr. A 2014, 1355, 296. 10 F. Hoffmann, M. Fröba, Chem. Soc. Rev. 2011, 40, 608. 11 N. Tanaka, H. Kobayashi, K. Nakanishi, H. Minakuchi, N. Ishizuka, Anal. Chem. 2001, 73, 420. 12 R. Göbel, P. Hesemann, A. Friedrich, R. Rothe, H. Schlaad, A. Taubert, Chem.-Eur. J. 2014, 20, 17579. 13 L. Yan, Q. Zhang, W. Zhang, Y. Feng, L. Zhang, T. Li, Y. Zhang, Electrophoresis 2005,26, 2935. 14 Z. Zhang, H. Lin, J. Ou, H. Qin, R. Wu, J. Dong, H. Zou, J. Chromatogr. A 2012, 1228, 263. 15 Z. Zhang, F. Wang, J. Ou, H. Lin, J. Dong, H. Zou, Anal. Bioanal. Chem. 2013, 405, 2265. 16 Z. Lin, X. Tan, R. Yu, J. Lin, X. Yin, L. Zhang, H. Yang, J. Chromatogr. A 2014, 1355, 228. 17 F. Hoffmann, M. Fröba, Chem. Soc. Rev. 2011, 40, 608. 18 D. J. Kim, J. S. Chung, W. S. Ahn, G.W. Kang, W. J. Cheong, Chem. Lett. 2004, 33, 422. 19 D. Lin, L. Hu, Z. Li, D. A. Loy, J. Porous Mater. 2014, 21, 39. 20 C. Vercaemst, M. Ide, H. Friedrich, K. P. de Jong, F. Verpoort, P. Van Der Voort, J. Mater. Chem. 2009, 19, 8839. 21 S. Park, M. Moorthy, C. Ha, NPG Asia Materials 2014, 6, 96. 22 M. I. López, D. Esquivel, C. Jiménez-Sanchidrián, F. J. Romero-Salguero, P. Van Der Voort, J. Catal. 2015, 326, 139. 23 M. Ide, E. De Canck, I. Van Driessche, F. Lynen, P. Van Der Voort, RSC Advances 2015, 5, 5546. 24 H. Zhong, G. Zhu, J. Yang, P. Wang, Q. Yang, Microporous Mesoporous Mater. 2007, 100, 259. 25 N. Husing, D. Brandhuber, P. Kaiser, J. Sol-Gel Sci. Techn. 2006, 40,131.

ACS Paragon Plus Environment

Page 5 of 6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Analytical Chemistry

26 D. Brandhuber, H. Peterlik, N. Huesing, Small 2006, 2, 503. 27 K. Nakanishi, Y. Kobayashi, T. Amatani, K. Hirao, T. Kodaira, Chem. Mater. 2004, 16, 3652. 28 L. J. Yan, Q. H. Zhang, Y. Q. Feng, W. B. Zhang, T. Li, L. H. Zhang, Y. K. Zhang, J. Chromatogr. A 2006, 1121, 92. 29 M. Zheng, G. Ruan, Y. Feng, J. Chromatogr. A 2009, 1216, 7739. 30 C. E. Hoyle, C. N. Bowman, Angew. Chem. Int. Ed. 2010, 49, 1540. 31 F. Gritti, G. Guiochon, J. Chromatogr. A 2006, 1115, 142. 32 M. Zheng, B. Lin, Y. Feng, J. Chromatogr. A 2007, 1164, 48. 33 A. Solivena, G. Dennisa, G. Guiochonc, E. Hilderd, P. Haddadd, R. Shalliker, J. Chromatogr. A 2010, 1217, 6085. 34 J. Ou, G. T. T. Gibson, R. D. Oleschuk, J. Chromatogr. A 2010, 1217, 3628. 35 H. Zhang, J. Ou, Z. Liu, H. Wang, Y. Wei, H. Zou, Anal. Chem. 2015, 87, 8789.

ACS Paragon Plus Environment

Analytical Chemistry

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 6

For Table of Contents Only

A novel type of PMO monolith with stable Si-C bonds in the skeleton and an extremely large surface was synthesized by a one-step “sol-gel” condensation of a single ethylene-bridged alkoxysilane precursor. With highly loaded vinyl groups that are homogeneously distributed throughout the skeleton of the monolith, the structure can be facilely functionalized with various groups by effective thiol-ene “click” chemistry for widespread applications. Herein, with “click” modification of C18, the obtained monolith was successfully applied for capillary liquid chromatography separation of small molecules and proteins.

ACS Paragon Plus Environment

6