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1.
We have prepared chiral fluorescent bisboronic acid sensors with 3,6-dithiophen-2-yl-9H-carbazole as the fluorophore. The thiophene moiety was used to extend the π-conjugation framework of the fluorophore in order to red-shift the fluorescence emission and, at the same time, to enhance the novel process where the fluorophore serves as the electron donor of the photoinduced electron transfer process (d-PET) of the boronic acid sensors; i.e., the background fluorescence of the sensor 1 at acidic pH is weaker compared to that at neutral or basic pH, in stark contrast to the typical a-PET boronic acid sensors (where the fluorophore serves as the electron acceptor of the photoinduced electron transfer process). The benefit of the d-PET boronic acid sensors is that the recognition of the hydroxylic acids can be achieved at acidic pH. We found that the thiophene moiety is an efficient π-conjugation linker and electron donor; as a result, the d-PET contrast ratio of the sensors upon variation of the pH is improved 10-fold when compared to the previously reported d-PET sensors without the thiophene moiety. Enantioselective recognition of tartaric acid was achieved at acid pH, and the enantioselectivity (total response K(D)I(F)(D)/K(L)I(F)(L)) is 3.3. The fluorescence enhancement (I(F)(Sample)/I(F)(Blank)) of sensor 1 upon binding with tartaric acid is 3.5-fold at pH 3.0. With the fluorescent bisboronic acid sensor 1, enantioselective recognition of mandelic acid was achieved for the first time. To the best of our knowledge, this is the first time that the mandelic acid has been enantioselectively recognized using a chiral fluorescent boronic acid sensor. Chiral monoboronic acid sensor 2 and bisboronic acid sensor 3 without the thiophene moiety failed to enantioselectively recognize mandelic acid. Our findings with the thiophene-incorporated boronic acid sensors will be important for the design of d-PET fluorescent sensors for the enantioselective recognition of α-hydroxylic acids such as mandelic acid, given that it is currently a challenge to recognize these analytes with boronic acid fluorescent molecular sensors. 相似文献
2.
The tetrahydroxyl derivative of BINOL, (S)- or (R)-1, and its analogues are synthesized. (S)- or (R)-1 can be used to conduct the enantioselective recognition of chiral amino alcohols. In comparison with BINOL, the two additional hydroxyl groups of (S)- or (R)-1 have increased the binding of this compound with the amino alcohols and significantly improved the fluorescence quenching efficiency. The fluorescence responses of (S)- or (R)-1 toward amino alcohols are compared with those of its analogues (R)-4 and (R)-6. It shows that the interaction of the central naphthyl hydroxyl groups of (S)- or (R)-1 with the substrates is responsible for the observed fluorescence quenching, and the two additional alkyl hydroxyl groups increase the quenching efficiency. 相似文献
3.
The cyclohexane-1,2-diamine-based bisbinaphthyl macrocycles (S)-/(R)-5 and their cyclic and acyclic analogues are synthesized. The interactions of these compounds with various chiral acids are studied. Compounds (S)-/(R)-5 exhibit highly enantioselective fluorescent responses and high fluorescent sensitivity toward alpha-hydroxycarboxylic acids and N-protected amino acids. Among these interactions, (S)-mandelic acid (10(-3) M) led to over 20-fold fluorescence enhancement of (S)-5 (1.0 x 10(-5) M in benzene/0.05% DME) at the monomer emission, and (S)-hexahydromandelic acid (10(-3) M) led to over 80-fold fluorescence enhancement. These results demonstrate that (S)-5 is useful as an enantioselective fluorescent sensor for the recognition of the chiral acids. On the basis of the study of the structures of (S)-5 and the previously reported 1,2-diphenylethylenediamine-based bisbinaphthyl macrocycle (S)-4, the large fluorescence enhancement of (S)-5 with a chirality-matched alpha-hydroxycarboxylic acid is attributed to the formation of a structurally rigidified host-guest complex and the further interaction of this complex with the acid to suppress the photoinduced electron-transfer fluorescent quenching caused by the nitrogens in (S)-5. 相似文献
4.
5.
Xuan He Xin Cui Maosi Li Lili Lin Xiaohua Liu Xiaoming Feng 《Tetrahedron letters》2009,50(42):5853-5856
A highly enantioselective fluorescent sensor, containing benzylaminomethyl groups at 3,3′-position of 1,1′-bi-2-naphthol (BINOL), has been used to conduct the chiral recognition of α-amino acid derivatives. It is observed that one enantiomer of N-Boc-proline can increase the fluorescence intensity of the binaphthyl fluorophores by over 57-fold, while the other enantiomer can cause only sixfold fluorescence enhancement. Such unusually highly enantioselective response demonstrates that this sensor is potentially useful in the enantioselective recognition of amino acid derivatives. 相似文献
6.
《Tetrahedron: Asymmetry》2006,17(14):2143-2148
New chiral fluorescence macrocycles 1 and 2 containing naphthalene and amino acid units were synthesized. The binding properties for amino acid anions were examined by the fluorescence and 1H NMR spectra. The results indicated good enantioselectivity of 1 toward the N-protected phenylalanine anions. 相似文献
7.
《中国化学快报》2022,33(9):4405-4410
The development of a single analytical platform with different functions is highly desirable but remains a challenge at present. Here, a paper-based device based on fluorescent carbon dots (CDs) functionalized paper/MnO2 nanosheets (MnO2 NS) hybrid devices (PCD/NS) was proposed for single-device multi-function applications. MnO2 NS functioned as a fluorescence quencher of CDs and recognizer of H2O2 released from the oxidase catalyzed system. Fluorescence recovery would occur after the decomposition of MnO2 NS induced by H2O2, by which a simple and effective strategy could be developed for fluorescence monitoring multiplex biological events. Xanthine (XA) sensing, xanthine oxidase (XOD) inhibitors screening analysis and chiral recognition of glucose enantiomers were performed on PCD/NS to investigate the multifunctional application of the paper-based device. By means of PCD/NS, XA could be determined in the range of 0.1–40 µmol/L with a low detection of limit of 0.06 µmol/L. The IC50 value of allopurinol, the model inhibitor of XOD, was sensitively detected to be 7.4 µmol/L. Glucose enantiomers were also recognized in terms of the specific fluorescence response to d-glucose. This work firstly presented a paper-based device capable of biomarkers detection, inhibitors screening and chiral recognition, which enlightened a promising strategy for the construction of multifunctional devices and hold the great potential application in clinical diagnosis and drug discovery. 相似文献
8.
Wolfgang Lindner 《Mikrochimica acta》1991,104(1-6):113-128
In this brief overview diverse chiral recognition models and chiral host-guest (selector-selectand, SO-SA) relationships which are used in enantioselective chromatography are discussed. In particular it is focussed on aspects of chiral interactions on (a) small molecular brush type chiral stationary phases (CSPs) and on (b) biopolymer and synthetic polymer type CSPs. The importance and the great variability of intermolecular SO-SA bindings via complementary contact sites, also in connection with molecule conformations, is stressed. Some representative and selected examples of chromatographic enantioseparations are presented. 相似文献
9.
Enantioselective fluorescent recognition of mandelic acid by unsymmetrical salalen and salan sensors
Yang X Liu X Shen K Fu Y Zhang M Zhu C Cheng Y 《Organic & biomolecular chemistry》2011,9(17):6011-6021
As sensors with multiple chiral centers, salalen 1 and salan 2 composed of trans-cyclohexane-1,2-diamine (trans-DACH) and 1,1'-bi-2-naphthol (BINOL) units were designed and synthesized. Fluorescent recognition studies of resulting sensors towards mandelic acid (MA) reveal that salan 2a containing (R)-BINOL and (R,R)-DACH exhibits highly sensitive and enantioselective response towards MA. The relationship between the chirality combination and the enantioselectivity is discussed. Based on the studies of concentration and solvent effect on the recognition process of 2a, it was found that the sensitivity and enantioselectivity could be enhanced via changing the concentration of sensors or altering the polarity of solvents. To explain why higher enantioselectivity can be achieved in moderate polar solvent other than in nonpolar or polar solvent, a solvent-guest competition mechanism, which may shed a light on the enhancement of the enantioselectivity of chiral recognition and noncovalent asymmetric catalysis, has been proposed and validated. 相似文献
10.
Wong WL Huang KH Teng PF Lee CS Kwong HL 《Chemical communications (Cambridge, England)》2004,(4):384-385
Terpyridine macrocycle 1 is shown to be a strong chelating agent for organic ammonium salts and also a useful chromophore in fluorescent sensing. It exhibits very good enantioselectivity (K(obs)(S)/K(obs)(R)= 3.8) in chiral discrimination of alpha-phenylglycine methyl ester hydrochloride (PhEtOMe). 相似文献
11.
《Electrochemistry communications》2002,4(7):550-553
Carbon supported platinum–ruthenium alloy catalyst prepared by reverse micelles method for was proposed. The particle size and morphology of catalyst were determined by XRD and TEM and found to be homogeneously dispersed on carbon support with narrow particle size distribution. The performance of the Pt–Ru/C catalyst was tested by cyclic voltammogram and galvanostatic polarization experiments in 1 M sulfuric acid with 2 M methanol solution at room temperature and showed a higher catalytic activity when compared with the standard Pt–Ru/C (E-TEK) catalyst. 相似文献
12.
《Tetrahedron: Asymmetry》1998,9(22):3979-3984
A new chiral titanium reagent, derived from optically active trans-1,2-dicamphorsulfonamidocyclohexane 2a and Ti(OiPr)4, was found to promote the enantioselective addition of diethylzinc to various aldehydes giving rise to the corresponding alcohols in high yields with moderate to high selectivity. 相似文献
13.
Jing Lin 《Tetrahedron》2004,60(49):11277-11281
Benzylaminomethyl groups are introduced to the 3,3′-positions of BINOL. The resulting compounds can be used to conduct the enantioselective fluorescent recognition of mandelic acid and N-benzyloxycarbonylphenylglycine. In the presence of (S)-mandelic acid, compound (R)-2 showed over 30-fold fluorescence enhancement with the ef [ef=enantiomeric fluorescence difference ratio=(IS−I0)/(IR−I0)] up to 4.2. In the presence of d-N-benzyloxycarbonylphenylglycine, compound (RR)-4 showed up to 15-fold fluorescence enhancement with the ef up to 5.0. These high fluorescence sensitivity and enantioselectivity make compounds (R)-2 and (RR)-4 practically useful sensors for the recognition of the chiral acids in apolar solvents. 相似文献
14.
Koichi Tanaka Takeshi Tsuchitani Noriaki Fukuda Asuka Masumoto Ryuichi Arakawa 《Tetrahedron: Asymmetry》2012,23(3-4):205-208
Calixarene-like chiral salen macrocycles can be used for the enantioselective fluorescent recognition of mandelic acid derivatives. It was observed that one enantiomer of mandelic acid causes a 28-fold increase in the fluorescence intensity of a chiral salen macrocycle, whereas the other enantiomer causes only a 14-fold fluorescence enhancement. This highly enantioselective fluorescent response makes chiral salen macrocycles useful for the enantioselective fluorescent recognition of some mandelic acid derivatives. 相似文献
15.
Miller TC Mann G Havrilla GJ Wells CA Warner BP Baker RT 《Journal of combinatorial chemistry》2003,5(3):245-252
A powerful high-throughput screening technique is described for the rapid screening of bead-based libraries for catalyst discovery and molecular recognition. Micro-X-ray fluorescence (MXRF) screens materials for elemental composition with mesoscale analysis. This method is nondestructive and requires minimal sample preparation and no special tags for analysis, and the screening time is dependent on the desired sensitivity. The speed, sensitivity, and simplicity of MXRF as a high-throughput screening technique were applied to screen bead-based libraries of oligopeptides for phosphate hydrolysis catalysts and molecular recognition of selective receptors for the degradation products and analogues of chemical warfare agents. This paper demonstrates the analytical or HTS capability of MXRF for combinatorial screening. It is meant only to show the capabilities of MXRF and is not meant as an exhaustive study of the catalyst and molecular recognition systems presented. 相似文献
16.
《Tetrahedron: Asymmetry》2007,18(15):1769-1774
The fluorescent photoinduced electron transfer (PET) chemosensors 1–3 based on (S)-1,1′-bi-2-naphthol were designed for their recognition of dibenzoyl tartrate anions. The binding properties for hydroxy acid anions were examined by the fluorescence and 1H NMR spectra. The results indicated that receptor 1 exhibit excellent enantioselectivity toward the enantiomers of dibenzoyl tartrate anion. 相似文献
17.
Nobuyuki MaseTakahiro Ohno Naoki HoshikawaKazuhiro Ohishi Hironao MorimotoHidemi Yoda Kunihiko Takabe 《Tetrahedron letters》2003,44(21):4073-4075
A new C3 symmetric amine-based chiral phase-transfer catalyst was synthesized. Application of the chiral PTC (1 mol%) in the alkylation of a tert-butyl glycinate-benzophenone Schiff base under mild reaction conditions provided an alkylated product with up to 58% enantiomeric excess. 相似文献
18.
The mechanism of the oxidation of di-tert-butyl disulfide (1) to the chiral thiosulfinate (2) by H(2)O(2) catalyzed by bis(acetylacetonato)oxovanadium and a chiral Schiff-base ligand (3) has been investigated. Techniques included (51)V NMR spectroscopy, solvent effects on reaction enantioselectivity, and the isolation and full characterization of a 2:1 ligand-to-vanadium catalyst precursor. A model for the dramatic solvent effect on the enantioselectivity of this reaction was developed, based on the identification of a competing nonselective oxidation pathway. From this model, strategies for limiting this competing pathway were developed. 相似文献
19.
E. Tobler M. Lämmerhofer W. R. Oberleitner N. M. Maier W. Lindner 《Chromatographia》2000,51(1-2):65-70
Summary An enantioselective liquid-solid batch extraction method is described for the screening of novel chiral stationary phases
(CSPs) during optimization studies of chiral selectors derived form a common lead structure. Extraction enantioselectivity
(α) values can be calculated from the enantiomeric excess ee-values of the selectand, which are measured in the liquid phase
by enantioselective HPLC. Extraction α-values have been correlated with chromatographic α-values. The influence was studied
of several experimental parameters of the assay (pHa, buffer concentration, temperature, selector/selectand and phase ratio) on the enantiomeric excess (ee) values of the selectands and the enantioselectivity of the CSPs, respectively. The derived statistically significant model
has then been implemented to predict chromatographic α-values of novel CSPs. For example, an ee of 89.3% for DNB-Leu as selectand
could be achieved in batch extraction for a novel synthesized but mechanistically similarly-acting CSP derived form quinine.
This corresponds to a calculated extraction α-value of 17.7. Based on this αextraction a chromatographic α-value of 28.8 was predicted by the linear correlation model; the experimental HPLC α-value of 31.7 was
in good agreement and demonstrated the validity of the proposed screening method. The method is particularly helpful in SO
optimization studies. 相似文献
20.
Fluorescent boronic acids that change fluorescent properties upon carbohydrate binding are very useful for the preparation of fluorescent sensors for sugars. Herein we report 5-quinolineboronic acid (5-QBA) that shows significant fluorescent property changes through a unique pKa-switching mechanism upon binding a diol in aqueous solution. 相似文献