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1.
Anal Chem ; 96(5): 2173-2182, 2024 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-38261544

RESUMO

Enantioselective discrimination of chiral molecules is essential in chemistry, biology, and medical science due to the configuration-dependent activities of enantiomers. Therefore, identifying a specific amino acid and distinguishing it from its enantiomer by using nanomaterials with outstanding performance are of great significance. Herein, blue- and green-emitting chiral silicon nanoparticles named bSiNPs and gSiNPs, respectively, with excellent water solubility, salt resistance, pH stability, photobleaching resistance, biocompatibility, and ability to promote soybean germination, were fabricated in a facile one-step method. Especially, chiral gSiNPs presented excellent fluorescence recognition ability for glutamic acid enantiomers within 1 min, and the enantiomeric recognition difference factor was as high as 9.0. The mechanism for enantiomeric fluorescence recognition was systematically explored by combining the fluorescence spectra with density functional theory (DFT) calculation. Presumably, the different Gibbs free energy and hydrogen-bonding interaction of the chiral recognition module with glutamic acid enantiomers mainly contributed to the difference in the fluorescence signals. Most noteworthy was the fact that the chiral gSiNPs can showcase not only the ability to recognize l- and d-glutamic acids in living cells but also the test strips fabricated by soaking gSiNPs can be applied for d-glutamic acid visual detection. As a result, this study provided insights into the design of multifunctional chiral sensing nanoplatforms for enantiomeric detection and other applications.


Assuntos
Ácido Glutâmico , Nanopartículas , Silício , Estereoisomerismo , Aminoácidos/química , Nanopartículas/química , Corantes
2.
Chirality ; 35(7): 411-417, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36943171

RESUMO

Fluorescent materials with large Stokes shifts have significant potential for use in optical applications. Typically, a synthetic design strategy is utilized for this purpose. In this study, we demonstrated a novel method by binding a chiral template to a nonchiral fluorescent agent without chemical modification. Specifically, α-helical poly(L-lysine) was employed as the chiral template, which interacted with a disulfonic fluorescent dye, such as NK2751. The dye caused excimer luminescence by inducing the formation of a chirally H-aggregated dimer only when poly(L-lysine) was in an α-helical shape. The result was a Stokes shift of 230 nm. Similar effects were not observed when the chiral template was in a random coil condition and the Stokes shift was less than 40 nm. These findings imply that H-aggregated dimerization, which often results in quenching, permits the electronic transitions necessary for fluorescence events by the formation of the chirally twisted state. In addition, we introduce for the first time the generation of circularly polarized luminescence using the chirality induction phenomena in a dye supported by poly(L-lysine).

3.
Mikrochim Acta ; 189(11): 401, 2022 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-36190563

RESUMO

In view of the limitations of existing berberine solid-phase extraction adsorbents, this paper proposes a novel carbonized π-conjugated polymer-coated porous silica (SiO2@C-π-CP) adsorbent with simple process and low cost for efficient extraction of berberine by multiple interactions. Characterization methods, including Brunner-Emmet-Teller measurement, thermogravimetric analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques, were used to verify the successful modification of carbonized π-conjugated polymer on the surface of porous silica. The berberine was selected as target molecule, and the adsorption mechanism and process were investigated through adsorption kinetics, adsorption isotherms, and thermodynamic studies. The fitting results show that the adsorption of berberine by SiO2@C-π-CP well conforms to the pseudo-second-order and Langmuir models. By optimizing the main SPE parameters, the SPE method based on SiO2@C-π-CP was developed. Excellent results were obtained, including low limit of detection (0.75 ng mL-1) and limit of quantification (2 ng mL-1), wide linearity (2-13,000 ng mL-1), and satisfactory relative standard deviations (RSD) of inter-day (1.5%) and intra-day (6.2%). Finally, the SiO2@C-π-CP also has been successfully used to the enrichment of berberine in real urine samples. This research makes clear that SiO2@C-π-CP has outstanding potential for trace enrichment of berberine alkaloids.


Assuntos
Berberina , Dióxido de Silício , Limite de Detecção , Polímeros/química , Porosidade , Dióxido de Silício/química
4.
Soft Matter ; 17(17): 4615-4622, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33949589

RESUMO

Two thermoresponsive copolymers with different lower critical solution temperatures (LCSTs) were crosslinked using silica nanoparticles to afford hybrid hydrogels exhibiting two distinct thermo-responsivities. The thermo-responsive copolymers were synthesised by free radical polymerisation from a monomer with a reactive side chain (3-methacryloxypropyl trimethoxysilane (S)) and water-soluble monomers with different thermo-responsivities (N-isopropyl acrylamide (N) or N-(3-methoxy propyl)acrylamide (M)). The obtained reactive copolymers, poly(N-isopropyl acrylamide-co-3-methacryloxypropyl trimethoxysilane) (pNS) and poly(N-(3-methoxy propyl acrylamide-co-3-methacryloxypropyl trimethoxysilane)) (pMS), were characterized by multiple techniques including 1H NMR and FTIR spectroscopy. The hetero-network hybrid hydrogels were easily prepared by mixing aqueous solutions of the copolymer with an aqueous colloidal silica suspension; their gelation properties could be tuned by varying the amounts of pNS, pMS, and Si. Differential scanning calorimetric analysis showed that the hetero-network hydrogel exhibited a critical two-step phase transition at temperatures around the LCST of each copolymer (33 °C for pNS, 73 °C for pMS), indicating that each polymer does not disturb the phase transitions of the other. The deswelling of the hetero-network hydrogel could be controlled with respect to temperature and time.

5.
Chemistry ; 25(43): 10141-10148, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31095789

RESUMO

In this work, a new class of totally organic fluorescent nanogel particles and their exceptionally specific behaviors based on their unique structures are introduced, which draws a sharp line from conventional fluorophore-doped and fluorophore-branched-type particles. The nanogel particles, the diameter of which could be controlled by adjusting reaction conditions, such as the solvent system, were spontaneously fabricated with a spherical shape by direct polymerization of non-heterocyclic aromatic compounds, such as 2,6-dihydroxyanthracene, 2,6-dihydroxynaphthalene, and 9,9-bis(4-hydroxyphenyl)fluorene with triazinane as the cross-linker. A fluorophoric moiety formed from a polymer main chain was realized in the particle, and consequently, the resultant content of the fluorophoric moiety was around 70-80 wt % per particle. The uniqueness and versatility of the particles can be emphasized by their good compatibility with various solvents due to their amphiphilic and ampholytic swelling properties, but also by their remarkable fluorescent solvatochromism in the dispersion state. Furthermore, these behaviors were preserved even in their polymer composite system. This study also demonstrates that various fluorescent polymer films can be fabricated with emission color control due to memorization of the solvatochromism phenomenon of the dispersed fluorescent nanoparticles.

6.
J Sep Sci ; 41(21): 3957-3965, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30136755

RESUMO

Novel zwitterionic polymer-grafted porous silica microspheres were prepared by using sodium 2-bromoethanesulfonate to quaternize the pyridyl side chains of the polymer, which is anchored on the surface of porous silica. The separation behavior for toluene and benzoic acid proved that the zwitterionic polymer-grafted porous silica worked as a stationary phase in hydrophilic interaction/ion exchange mixed-mode chromatography. Compared with a conventional sulfobetaine-based zwitterion-grafted porous silica column, the prepared poly(vinylpyridinium ethanesulfonate)-immobilized porous silica afforded the highly selective separation of benzoic acid derivatives over a wide pH range, and the separation behavior was quite sensitive to the protonation state of the carboxylic acids. The high selectivity was attributed to the multiple interactions between the guest molecule and the zwitterionic groups on the polymer chains. The new zwitterionic stationary phase demonstrated excellent selectivity for hydrophilic biorelated molecules such as nucleobases and nucleosides.

7.
Langmuir ; 33(40): 10679-10689, 2017 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-28914544

RESUMO

Hollow silica microspheres with orderly protrusions on their outer and inner surfaces were fabricated in three simple steps: (1) suspension polymerization of a polymerizable monomer containing silica nanoparticles to obtain polymeric microspheres with a layered shell of silica particles; (2) sol-gel reaction of tetraethoxysilane (TEOS) on the surface of the microspheres to connect the silica nanoparticles; (3) removal of polymer core by calcination. The shell composed of silica-connected silica nanoparticles remained spherical even after calcination, and the characteristic surface morphology with protrusions were obtained on both inner and outer surfaces. Measurements of the mechanical strength revealed that the compression modulus of the hollow microspheres increased with increasing thickness of the silica layer, which could be controlled by changing the concentration of TEOS in the sol-gel reaction. Rapid heating of the hollow silica microspheres with the thin silica-connected layer led to silica shell cracking, and the cracks were mostly observed in the connecting layer between the silica nanoparticles. The stress was probably concentrated in the connecting layer because of its lower thickness than the nanoparticles. Such characteristic of the hollow microspheres is useful for a capsule with capability for heat-induced controlled cracking caused by internal pressure changes.

8.
Nano Lett ; 16(10): 6411-6415, 2016 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-27585220

RESUMO

Synthesis of chiral inorganic or hybrid nanomaterials through sol-gel transcription of chiral organic templates has attracted a great deal of interest for more than a decade. However, the chiral nature of these inorganic matrices has never been directly observed. For the first time, we report a direct evaluation of chirality on noncrystalline silica chiral nanoribbons by vibrational circular dichroism (VCD) measurements. Strong Cotton effect around 1150-1000 cm-1 from Si-O-Si asymmetric stretching vibration was observed. Surprisingly, calcination of these hybrid nanoribbons doubled the intensity of Cotton effects. On the basis of transmission electron microscopy observations, IR, VCD, NMR, and Raman spectroscopies, we demonstrate that the silica chirality originates from twisted siloxane network composed of chiral arrangement of the Si-O-Si bonds. Our findings clearly prove the presence of chiral organization of amorphous silica network, making them very promising chiral platforms for chiral recognition, optical applications, or asymmetric catalysis.

9.
Angew Chem Int Ed Engl ; 56(11): 2989-2993, 2017 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-28146313

RESUMO

A new strategy is described for generating strong circularly polarized luminescence with highly tunable emission bands through chiral induction in nonchiral, totally organic, low-molecular-weight fluorescent dyes by chiral nanotemplate systems. Our approach allows the first systematic investigation to clarify the correlation between the circular dichroism and circularly polarized luminescence intensities. As a result, a dilute solution system with the highest circularly polarized luminescence intensity achieved to date and a dissymmetry factor of over 0.1 was identified.

10.
Photochem Photobiol Sci ; 15(12): 1476-1483, 2016 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-27874144

RESUMO

Photosensitizers (PS) are used in photodynamic therapy to treat several cancers. The efficacy of photodynamic therapy (PDT) could be further improved by overcoming aggregation-dependent quenching of PS and by improving the biodistribution of the PS. In this work we attempted to overcome these issues by conjugating a PS with a lipid molecule and tested the liposomes prepared with this PS conjugated lipid for PDT. A novel lipid-porphyrin conjugate (1 : 1) was synthesized by attaching a PS, 5-(4-methoxycarbonylphenyl)-10,15,20-triphenyl-21H,23H-porphine, to the head group of a glutamide lipid. Two liposomal preparations, with egg phosphatidylcholine as the bulk lipid, were prepared viz. liposomes with PS conjugated lipid (LPSL) and PS entrapped in liposomes (PSL). At equimolar concentrations of the PS, both liposomal preparations were found to generate comparable amounts of reactive oxygen species as free PS upon light exposure. Electron micrographs and dynamic light scattering measurements indicated uniform and circular liposomes of 150 nm in size and near neutral zeta potential. Uptake of these liposomes by the human ovarian carcinoma cell line, SK-OV-3, was shown by FACS and confocal microscopy. Upon light exposure, the LPSL, i.e., with the conjugate lipid, have shown a substantial decrease (>4 times) in the PS requirement compared to PSL or free PS in its ability to cause light mediated cell death of SK-OV-3 cells. The light mediate cell death by LPSL was shown to be not dependent on the bulk properties of the lipid. Our data suggest a potential benefit of conjugating PS with a lipid in improving the efficiency of PDT.


Assuntos
Fotoquimioterapia , Fármacos Fotossensibilizantes/química , Morte Celular/efeitos dos fármacos , Morte Celular/efeitos da radiação , Linhagem Celular Tumoral , Humanos , Luz , Lipídeos/química , Lipossomos/química , Fármacos Fotossensibilizantes/metabolismo , Fármacos Fotossensibilizantes/farmacologia , Distribuição Tecidual
11.
Angew Chem Int Ed Engl ; 55(24): 6848-52, 2016 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-27101565

RESUMO

Disulfide bridge formation was investigated in helical aromatic oligoamide foldamers. Depending on the position of thiol-bearing side chains, exclusive intramolecular or intermolecular disulfide bridging may occur. The two processes are capable of self-sorting, presumably by dynamic exchange. Quantitative assessment of helix handedness inversion rates showed that bridging stabilizes the folded structures. Intermolecular disulfide bridging serendipitously yielded a well-defined, C2 -symmetrical, two-helix bundle-like macrocyclic structure in which complete control over relative handedness, that is, helix-helix handedness communication, is mediated remotely by the disulfide bridged side chains in the absence of contacts between helices. MM calculations suggest that this phenomenon is specific to a given side chain length and requires disulfide functions.

12.
Anal Chem ; 87(13): 6614-21, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26041430

RESUMO

For the first time, we synthesized multiple embedded polar groups (EPGs) containing linear C18 organic phases. The new materials were characterized by elemental analysis, IR spectroscopy, (1)H NMR, diffuse reflectance infrared Fourier transform (DRIFT), solid-state (13)C cross-polarization magic angle spinning (CP/MAS) NMR, suspended-state (1)H NMR, and differential scanning calorimetry (DSC). (29)Si CP/MAS NMR was carried out to investigate the degree of cross-linking of the silane and silane functionality of the modified silica. Solid-state (13)C CP/MAS NMR and suspended-state (1)H NMR spectroscopy indicated a higher alkyl chain order for the phase containing four EPGs than for the phase with three EPGs. To correlate the NMR results with temperature-dependent chromatographic studies, standard reference materials (SRM 869b and SRM 1647e), a column selectivity test mixture for liquid chromatography was employed. A single EPG containing the C18 phase was also prepared in a similar manner to be used as a reference column especially for the separation of basic and polar compounds in reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC), respectively. Detailed chromatographic characterization of the new phases was performed in terms of their surface coverage, hydrophobic selectivity, shape selectivity, hydrogen bonding capacity, and ion-exchange capacity at pH 2.7 and 7.6 for RPLC as well as their hydrophilicity, the selectivity for hydrophilic-hydrophobic substituents, the selectivity for the region and configurational differences in hydrophilic substituents, the evaluation of electrostatic interactions, and the evaluation of the acidic-basic nature for HILIC-mode separation. Furthermore, peak shapes for the basic analytes propranolol and amitriptyline were studied as a function of the number of EPGs on the C18 phases in the RPLC. The chromatographic performance of multiple EPGs containing C18 HILIC phases is illustrated by the separation of sulfa drugs, ß-blockers, xanthines, nucleic acid bases, nucleosides, and water-soluble vitamins. Both of the phases showed the best performance for the separation of shape-constrained isomers, nonpolar, polar, and basic compounds in RPLC- and HILIC-mode separation of sulfa drugs, and other polar and basic analytes compared to the conventional alkyl phases with and without embedded polar groups and HILIC phases. Surprisingly, one phase would be able to serve the performance of three different types of phases with very high selectivity, and we named this phase the "smart phase". Versatile applications with a single column will reduce the column purchasing cost for the analyst as well as achieve high separation, which is challenging with the commercially available columns.


Assuntos
Compostos Orgânicos/química , Dióxido de Silício/química , Limite de Detecção , Espectroscopia de Ressonância Magnética
13.
J Sep Sci ; 38(14): 2403-13, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25944152

RESUMO

The amphiphilic polymer-grafted silica was newly prepared as a stationary phase in high-performance liquid chromatography. Poly(4-vinylpyridine) with a trimethoxysilyl group at one end was grafted onto porous silica particles and the pyridyl side chains were quaternized with 1-bromooctadecane. The obtained poly(octadecylpyridinium)-grafted silica was characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy and Brunauer-Emmett-Teller analysis. The degree of quaternization of the pyridyl groups on the obtained stationary phase was estimated to be 70%. The selective retention behaviors of polycyclic aromatic hydrocarbons including some positional isomers were investigated using poly(octadecylpyridinium)-grafted silica as an amphiphilic polymer stationary phase in high-performance liquid chromatography and results were compared with commercially available polymeric octadecylated silica and phenyl-bonded silica columns. The results indicate that the selectivity toward polycyclic aromatic hydrocarbons exhibited by the amphiphilic polymer stationary phase is higher than the corresponding selectivity exhibited by a conventional phenyl-bonded silica column. However, compared with the polymeric octadecylated silica phase, the new stationary phase presents similar retention behavior for polycyclic aromatic hydrocarbons but different retention behavior particularly for positional isomers of disubstituted benzenes as the aggregation structure of amphiphilic polymers on the surface of silica substrate has been altered during mobile phase variation.

14.
Anal Bioanal Chem ; 406(14): 3507-15, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24705959

RESUMO

This work reports a new imidazolium and L-alanine derived copolymer-grafted silica stationary phase for ready separation of complex isomers using high-performance liquid chromatography (HPLC). For this purpose, 1-allyl-3-octadecylimidazolium bromide ([AyImC18]Br) and N-acryloyl-L-alanine sodium salt ([AAL]Na) ionic liquids (IL) monomers were synthesized. Subsequently, the bromide counteranion was exchanged with the 2-(acrylamido)propanoate organic counteranion by reacting the [AyImC18]Br with excess [AAL]Na in water. The obtained IL cation-anion monomer pair was then copolymerized on mercaptopropyl-modified silica (Sil-MPS) via a surface-initiated radical chain-transfer reaction. The selective retention behaviors of polycyclic aromatic hydrocarbons (PAHs), including some positional isomers, steroids, and nucleobases were investigated using the newly obtained Sil-poly(ImC18-AAL), and octadecyl silylated silica (ODS) was used as the reference column. Interesting results were obtained for the separation of PAHs, steroids, and nucleobases with the new organic phase. The results showed that the Sil-poly(ImC18-AAL) presented multiple noncovalent interactions, including hydrophobic, π-π, carbonyl-π, and ion-dipole interactions for the separation of PAHs and dipolar compounds. Only pure water was sufficient as the mobile phase for the separation of the nucleobases. Ten nucleosides and bases were separated, using only water as the mobile phase, within a very short time using the Sil-poly(ImC18-AAL), which is otherwise difficult to achieve using conventional hydrophobic columns such as ODS. The combination of electrostatic and hydrophobic interactions are important for the effective separation of such basic compounds without the use of any organic additive as the eluent on the Sil-poly(ImC18-AAL) column.


Assuntos
Ânions , Cátions , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Polímeros/química , Alanina/química , Técnicas de Química Analítica , Ligação de Hidrogênio , Imidazóis/química , Íons , Espectroscopia de Ressonância Magnética , Nucleosídeos/química , Hidrocarbonetos Policíclicos Aromáticos/química , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Esteroides/química , Temperatura
15.
Anal Bioanal Chem ; 406(19): 4585-93, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24858469

RESUMO

A new hydrophilic and nonionic poly(2-vinyloxazoline)-grafted silica (Sil-VOX(n)) phase was synthesized and applied for the separation of nucleosides and nucleobases in hydrophilic interaction chromatography (HILIC). Polymerization and immobilization onto silica were confirmed by using characterization techniques including (1)H NMR spectroscopy, elemental analysis, and diffuse reflectance infrared Fourier transform spectroscopy. The hydrophilicity or wettability of Sil-VOX(n) was observed by measuring the contact angle (59.9°). The chromatographic results were compared with those obtained with a conventional HILIC silica column. The Sil-VOX(n) phase showed much better separation of polar test analytes than the silica column, and the elution order was different. Differences in selectivity between these two columns indicate that the stationary phase cannot function merely as an inert support for a water layer into which the solutes are partitioned from the bulk mobile phase. To elucidate the interaction mechanism, the separation of dihydroxybenzene isomers was performed on both columns in normal-phase liquid chromatography. Sil-VOX(n) was very sensitive to the dipole moments of the positional isomers of polycyclic aromatic compounds in normal-phase liquid chromatography. The interaction mechanism for Sil-VOX(n) in HILIC separation is also described.

16.
Nanoscale Adv ; 6(15): 3850-3856, 2024 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-39050944

RESUMO

Unique polymer hydrogels with unusual cross-linking networks and self-healing properties have been recently reported. In this study, we fabricated hybrid hydrogels consisting of a chiral supramolecular one-dimensional assembly of glutamide-derived lipids bearing pyridinium head groups (G-Py+) cross-linked with termini-anionised hydrophilic polyethylene glycol polymers (S-PEG n -S). The cationic group-linked G-Py+ forms nanotubular aggregates in water. G-Py+/S-PEG n -S aqueous mixtures formed hydrogels at certain concentrations and ambient temperatures. The terminal anionic sulfate groups play a key role in hydrogel formation, as evidenced by the absence of gelation in G-Py+/PEG n . The negative circular dichroism signal observed for pyridinium exhibited a blue shift upon the addition of S-PEG n -S but maintained its signal intensity even with excess S-PEG n -S, suggesting the chiral orientation of the nanofibrous G-Py+ self-assembly preserved even complexation with S-PEG n -S in hydrogel. The hybrid hydrogel of sulfated polyethylene glycol with nanofibrous chiral supramolecular assembly exhibited self-healing property at a temperature below the gel-to-liquid crystalline phase transition (T C) of G-Py+ aggregates, which was evidenced by the inversion fluid method and viscoelastic measurements.

17.
Chemistry ; 19(52): 18004-10, 2013 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-24353082

RESUMO

A novel sulfonic-azobenzene-functionalized amphiphilic silica material was synthesized through the preparation of a new sulfonic azobenzene monomer and its grafting on mercaptopropyl-modified silica by a surface-initiated radical chain-transfer reaction. The synthesis was confirmed by infrared spectra, elemental analysis, and thermogravimetric analysis. This new material was successfully applied as a new kind of mixed-mode stationary phase in liquid chromatography. This allows an exceptionally flexible adjustment of retention and selectivity by tuning the experimental conditions. The distinct separation mechanisms were outlined by selected examples of chromatographic separations in the different modes. In reversed-phase liquid chromatography, this new stationary phase presented specific chromatographic performance when evaluated using a Tanaka test mixture. Seven dinitro aromatic isomers, four steroids, and seven flavonoids were separated successfully in simple reversed-phase mode. This stationary phase can also be used in hydrophilic interaction chromatography because of the existing polar functional groups; for this, nucleosides and their bases were used as a test mixture. Interestingly, the same nucleosides and bases can also be separated in per aqueous liquid chromatography using the same stationary phase. Three ginsenosides including Rg1, Re, and Rb1 were successfully separated in hydrophilic mode. There is the potential for more applications to benefit from this useful column.


Assuntos
Compostos Azo/química , Cromatografia Líquida de Alta Pressão/métodos , Dióxido de Silício/química , Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas
18.
Langmuir ; 29(1): 417-25, 2013 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-23231048

RESUMO

A glutamide gelator, 1, was synthesized, and a weak emission enhancement was observed during its gelation. In addition, 1 could be an excellent scaffold for successfully embedding an energy acceptor, 2, into its aggregate to obtain highly efficient energy transfer. An amplification of the emission enhancement was observed in the two-component gels compared to that of the neat gel of 1 during gel formation. For example, 1 induced only a 2.5-fold increase in emission intensity, whereas a 23-fold enhanced emission could be observed in the two-component gel with only 1.6 mol % 2. Furthermore, two-component gels had an excited proton response. In systems with low acceptor concentrations, the hot solution red-shifted the fluorescence from blue to yellow upon the addition of a proton, which continuously blue-shifted with decreasing temperature to form the gel given that the binding of the gelator to the proton is weakened during coassembly. Moreover, the casting film formed by the two-component wet gel had an excellent response to volatile acids such as hydrochloric acid, trifluoroacetic acid, and so on and could be reversibly recovered by exposure to NH(3).

19.
Org Biomol Chem ; 11(11): 1840-7, 2013 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-23380938

RESUMO

Being different from common sensing molecules existing as monomer in solution, the gelators as sensing molecules self-assembled together in gels. Therefore, the interaction strength between gelators is believed as an important factor for gels to recognize selectively anions. In this paper, we choose two gelators, presenting similar binding sites for anions, but different strengths in intermolecular interaction. Moreover, their anion responsive behaviors in organogels were examined by observing phase state and measuring UV-vis and fluorescence spectra. We found that the organogel formed by 2 with strong intermolecular interaction could selectively recognize fluoride anion. However, the gels of 1 could be transformed into sol phases by addition of F(-), Cl(-), Br(-), AcO(-) and H(2)PO(4)(-) because of the small aggregate constant of 1 in o-dichlorobenzene, presenting poor selectivity. Moreover, their UV-vis and emission spectra acting as testing methods also suggested the same conclusion.


Assuntos
Géis/química , Ânions/química , Géis/síntese química , Estrutura Molecular
20.
J Chromatogr A ; 1693: 463885, 2023 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-36848731

RESUMO

We described two novel zwitterionic polymer-terminated porous silica stationary phases containing the same pyridinium cation and anions of different side chains (carboxylate and phosphonate groups) for use in hydrophilic interaction liquid chromatography (HILIC). These two novel columns were prepared by polymerizing 4-vinylpyridine and grafting it onto a silica surface, followed by quaternization reaction with 3-bromopropionic acid (Sil-VPC24) and (3-bromopropyl) phosphonic acid (Sil-VPP24), which possess positively charged pyridinium groups, and negatively charged carboxylate and phosphonate groups, respectively. The products obtained were verified through relevant characterization techniques such as elemental analysis, Fourier-transform infrared spectroscopy, thermogravimetric analysis, Zeta potential analysis, and Brunauer-Emmett-Teller analysis. The retention properties and mechanisms of different types of compounds (neutral, cationic, and anionic) on the two zwitterionic-modified silica stationary phases were studied by varying the buffer salt concentration and pH of the eluent. The separation of phenol and aromatic acids, disubstituted benzene isomers, sulfonamide drugs, as well as nucleosides/nucleobases were investigated on the two packed novel columns and a commercial zwitterionic column in identical HILIC mode, ensuring a thorough comparison between both novel columns and with a commercial standard. The results illustrated that various compounds could be separated up to various efficiencies based on the mechanism of hydrophilic interaction-based retention between the solutes and the two zwitterionic polymer stationary phases. The Sil-VPP24 column demonstrated the best separation performance out of the three, as well as flexible selectivity and excellent resolution. Both novel columns exhibited excellent stability and chromatographic repeatability for the separation of seven nucleosides and bases.


Assuntos
Nucleosídeos , Dióxido de Silício , Nucleosídeos/análise , Dióxido de Silício/química , Polímeros/análise , Porosidade , Cromatografia Líquida/métodos , Ácidos Carboxílicos , Interações Hidrofóbicas e Hidrofílicas
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