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ABSTRACT: A novel open-bowl pyramidal compound cyclotriveratrylene-carbazole (CTV-CZ) was designed and synthesized. Its absorption and emission spectroscopic properties in different organic solvents were characterized. Three absorption peaks of CTV-CZ around 235nm, 260nm and 290nm were observed. The fluorescence emission peaks were at about 353nm and 368nm using a solution of ∼10(-7)M CTV-CZ. The intermolecular interaction between CTV-CZ and fullerene (C60) was studied in detail by UV-vis absorption and fluorescence spectra. CTV-CZ could associate with C60 to form supramolecular complex with 1:1 molar ratio and the binding constant was estimated to be 5.0(6)×10(4)M(-1) by fluorimetry. The formation of inclusion complex for CTV-CZ and C60 was further confirmed by (1)H NMR and cyclic voltammetry. The downfield shift of protons of CTV-CZ in its (1)H NMR spectrum and the decrease of redox currents on addition of C60 showed that photo induced electron transfer (PET) occurred from the electron donor CTV and CZ units to the electron acceptor C60.
Talanta 03/2013; 106C:454-458. · 3.79 Impact Factor
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ABSTRACT: A ratiometric fluorescent probe for Ca(2+) based on 1,3,4-oxadiazole derivative has been designed and developed. The probe exhibits a large Stokes shift of 202 nm and a highly selective ratiometric emission response (490/582 nm) to Ca(2+) over other metal cations. Additionally, the probe can readily reveal the changes of intracellular Ca(2+) concentration in living human umbilical vein endothelial cells.
Organic & Biomolecular Chemistry 11/2012; · 3.70 Impact Factor
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ABSTRACT: A simple method of room temperature phosphorescence is proposed for the determination of propranolol enantiomeric composition based on β-cyclodextrin as the chiral host and bromocyclohexane as the heavy atom. Enantiomeric complexes are formed upon binding of the propranolol enantiomer to β-cyclodextrin, and the sign of the resultant phosphorescence signals allows for the identity of the propranolol enantiomers configuration to be determined successfully.
The Analyst 11/2012; · 4.23 Impact Factor
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ABSTRACT: A series of oxazole derivatives, 5-methyl-2-(p-methylphenyl)-4-acetyl oxazole (MMPAO), 5-methyl-2-(p-methoxyphenyl)-4-acetyl oxazole (MOPAO), 5-methyl-2-(p-N,N'-dimethylamino-phenyl)-4-acetyl oxazole (MDMAPAO) and 5-methyl-2-(p-N,N'-diphenylaminophenyl)-4-acetyl oxazole (MDPAPAO) have been synthesized and studied to compare their photophysical properties. The UV-visible absorption spectra of MDMAPAO and MDPAPAO are bathochromatically shifted as compared to that of MMPAO and MOPAO. The fluorescence emission of MDPAPAO is very sensitive to the polarity of solvents. The magnitude of change in the dipole moment was calculated using the Lippert-Mataga equation. MDPAPAO shows the highest change in the dipole moment (Δu=13.3D) than that of the other three oxazole derivatives. The spectral properties including fluorescence quantum yield and lifetime were determined in solvents with different polarities. MDPAPAO displays the highest fluorescence quantum yield and lifetime, following a bi-exponential fluorescent decay fashion. Our result demonstrates that the excited state of MDPAPAO possesses the property of intramolecular charge transfer.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2012; 102C:256-262. · 2.10 Impact Factor
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ABSTRACT: Nanoparticles of a novel boron-based carbazole derivative have been reported. They exhibit efficient green fluorescence, aggregation induced ratiometric fluorescence change and green/blue fluorescent switching to sense VOCs.
Chemical Communications 07/2012; 48(68):8586-8. · 6.17 Impact Factor
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ABSTRACT: A carbazole-based compound with intramolecular charge transfer (ICT) characteristics, 3,6-bis-((N-ethylcarbazole-3-)-propene-1-keto)-N-ethylcarbazole (BCzPCz) was synthesized by N-alkylation, acetylation and aldol condensation. BCzPCz was further confirmed by IR and (1) H NMR. The central N-ethylcarbazole was connected with two N-ethylcarbazole units through the propenone group in BCzPCz. N-ethylcarbazole and carbonyl groups were electron donors (D) and acceptors (A), respectively. The UV-vis absorption and fluorescence characteristics of BCzPCz were also investigated in different solvents. Solvatochromism was attributed to ICT complex formation in singlet excited state. Magnitude of the change in the dipole moment was 24.78 D according to Lippert-Mataga equation. Fluorescence of BCzPCz was significantly affected by pH and was quenched in acidic medium. Fluorescence quantum yield of BCzPCz was 0.516 in ethanol. Experimental results showed its potential use as a fluorescence probe and as two-photon absorption material. Copyright © 2012 John Wiley & Sons, Ltd.
Luminescence 07/2012; · 1.73 Impact Factor
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ABSTRACT: The inclusion interaction between propranolol (PPL) and p-sulfonatocalix[6]arene (SCX6) was investigated by fluorescence and (1)H NMR spectroscopy. Influences of pH, temperature, ionic strength and the concentration of SCX6 were examined in detail. In phosphate buffer solution with pH 7.5, the fluorescence of PPL dramatically quenched upon addition of SCX6 revealing the formation of inclusion complexes between PPL and SCX6. The stoichiometric ratio was verified to be 1:1 by the continuous variation method. The inclusion constant of PPL-SCX6 complexes was calculated as 2.2×10(4)L/mol by the nonlinear curve fitting method. (1)H NMR titration spectra testified that the aliphatic chain of PPL may be partially penetrated into the hydrophobic cavity of SCX6. This was confirmed by molecular dynamics calculations.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2012; 97:155-60. · 2.10 Impact Factor
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ABSTRACT: The binding mode and mechanism of the interactions between two planar cationic alkaloids chelerythrine (Che) and sanguinarine (San) with calf thymus DNA (ctDNA) were systematically investigated at pH 5.40 using UV-vis absorption spectroscopy, fluorescence spectroscopy and cyclic voltammetry. Che and San show strong fluorescence at 570 and 589 nm, respectively. Che displays fluorescence enhancement with ctDNA whereas the fluorescence of San is quenched on interaction with ctDNA. In addition, UV-vis spectra of both alkaloids show apparent hypochromicity and are bathochromic shifted, indicating that they could intercalate into ctDNA bases. The fluorescence polarization of Che and San increases in the presence of ctDNA, again implying the intercalation of two alkaloids with ctDNA. This conclusion was also supported by the results obtained from anion quenching and cyclic voltammetry. The binding constants of both alkaloids with ctDNA were calculated in the order of 10(5)L/mol. San binds with ctDNA 3-fold stronger than Che. The stoichiometric bindings are five nucleotides per Che or San. Electrostatic binding also exists between the alkaloids and DNA helix. Finally, theoretical calculations show that only certain parts of Che and San molecules intercalate into the DNA helix.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2012; 95:80-5. · 2.10 Impact Factor
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ABSTRACT: The interactions of ethyl violet (EV) with cyclodextrins (CDs) were investigated by Multi-wall carbon nanotubes/Nafion composite
film modified glassy carbon electrode (MWNTs/Nafion/GCE). It was found that the MWNTs/Nafion composite film can effectively
catalyze the electrode reaction of EV. The variation of the electrochemical behavior of EV upon the addition of CDs indicated
the formation of the inclusion complexes of EV with β-CD, heptakis (2,3,6-tri-O-methyl)-β-CD (TM-β-CD), heptakis (2,6-di-O-methyl)-β-CD (DM-β-CD), hydroxypropyl-β-CD (HP-β-CD), and carboxymethyl-β-CD (CM-β-CD). The stoichiometry ratios of EV and
the above five CDs were found to be 1:1. The inclusion ability obeyed the order: CM-β-CD>HP-β-CD>TM-β-CD>DM-β-CD>β-CD.
The results showed that the modified β-CDs exhibited stronger binding ability than native β-CD, especially the charged CM-β-CD,
which implied that the inclusion capacity depends on not only size matching and hydrophobicity but also electrostatic interaction.
1HNMR spectra and molecule mechanics calculations suggested that EV was included into the cavity of β-CD from the wider side.
KeywordsEthyl violet-Carbon nanotubes-Nafion-Cyclodextrin-Differential pulse voltammetry
Journal of Inclusion Phenomena 04/2012; 68(3):467-473. · 1.89 Impact Factor
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ABSTRACT: Multi-wall carbon nanotubes (CNTs)/Nafion composite membrane modified glassy carbon electrode (GCE) was fabricated to investigate
the redox of brilliant cresyl violet (BCV) and its supramolecular system with γ-CD and hydroxypropyl-γ-CD (HP-γ-CD). The cyclic
voltammetric results indicated that MWNTs/Nafion composite membrane was able to electrocatalyze the redox of BCV compared
with bare GCE. Under optimal conditions, differential pulse voltammetry (DPV) was used to study the inclusion interaction
of BCV with γ-CD and HP-γ-CD. The consequence demonstrated that the formation of complexes led to the rise of peak current
and the shift of peak potential. The inclusion constants of BCV dimer with γ-CD, HP-γ-CD are 2,650 and 8,040 L/mol, respectively.
UV–Vis spectra were also employed to confirm the formation of complexes. According to 1HNMR, the possible binding mode of BCV dimer with CDs was discussed.
Journal of Inclusion Phenomena 04/2012; 64(1):115-120. · 1.89 Impact Factor
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ABSTRACT: A novel boron-containing π-conjugated compound has been synthesized by the introduction of electron-acceptors (dimesitylboron groups) at the 3,3'-positions of a carbazole dimer (electron-donor). The compound possesses excellent electrochemical properties and high fluorescence quantum yields. In addition, is a sensitive fluorescence sensor with remarkable colour changes and the results could be confirmed through theoretical calculations of the compounds and [(n)Bu(4)N](+)(2)[·(F)(2)](2-). Our studies indicate that could be used as an excellent optoelectronic material in OLED devices and a ratiometric fluorescent chemosensor.
Organic & Biomolecular Chemistry 04/2012; 10(19):3852-8. · 3.70 Impact Factor
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ABSTRACT: A methanol-utilizing strain (ME25) using methanol (MeOH) as the sole carbon source has been isolated from methane-generating
pits. ME25 was identified as Methylobacterium organophilium by its physiological characteristics and 16SrDNA sequence. A MeOH biosensor was then developed by immobilizing ME25 along
with sensor for dissolved oxygen (O2). Its response is based on the depletion of O2 following oxidation of MeOH by the bacteria. The decrease in O2 is linearly related to the MeOH concentration in the range from 1.6mg·L−1 to 4800mg·L−1 and the detection limit for MeOH is 0.27mg·L−1. The response time of the biosensor is around 20min.
Microchimica Acta 04/2012; 167(1):67-73. · 3.03 Impact Factor
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ABSTRACT: A novel A-π-D-π-D-π-A type compound, containing two benzothiazole rings as electron acceptors and two N-ethylcarbazole groups as electron donors, (E)-1,2-bis(3-(benzothiazol-2-yl)-9-ethylcarbazol-6-yl)ethene (BBECE), was synthesized and characterized by elemental analysis, NMR, MS and thermogravimetric analysis. Electrochemical property of compound BBECE was studied by cyclic voltammetry analysis. The absorption and emission spectra of BBECE was experimentally determined in several solvents and simultaneously computed using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The calculated absorption and emission wavelengths are coincident with the measured data. The lowest-lying absorption spectra can be mainly attributed to intramolecular charge transfer (ICT), and the fluorescence spectra can be mainly described as originating from an excited state with intramolecular charge transfer (ICT) character. The molecular orbitals (HOMO and LUMO), the ionization potential (IP), the electron affinity (EA) and reorganization energy of compound BBECE were also investigated using density functional theory (DFT). The results show that compound BBECE exhibited excellent thermal stability and electrochemical stability as well as high fluorescence quantum yield, indicating its potential applications as an excellent optoelectronic material in optical fields.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 93:19-25. · 2.10 Impact Factor
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ABSTRACT: A novel Zn(2+) fluorescence probe, 2-[(N-ethyl carbazole)-3-sulfonyl ethylenediamine]-1-N,N-bis(2-methypyrbidy), was designed and synthesized via simple steps, and its structure was confirmed by IR and (1)H NMR. The probe gives significant fluorescence enhancement immediately following Zn(2+) addition at neutral pH and exhibits improved selectivity for Zn(2+) compared to the other metal ions in aqueous solution. The spectra and fluorescence quantum yield of the synthesized compound were carefully investigated by UV-vis absorption and fluorescence spectra in various solvents.
Bioorganic & medicinal chemistry letters 11/2011; 22(1):343-6. · 2.65 Impact Factor
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ABSTRACT: An amperometric glucose biosensor based on an n-alkylamine-stabilized palladium nanoparticles (PdNPs)-glucose oxidase (GOx) modified glassy carbon (GC) electrode has been successfully fabricated. PdNPs were initially synthesized by a biphase mixture of water and toluene method using n-alkylamines (dodecylamine, C₁₂-NH₂ and octadecylamine, C₁₈-NH₂) as stabilizing ligands. The performance of the PdNPs-GOx/GC biosensor was studied by cyclic voltammetry. The optimum working potential for amperometric measurement of glucose in pH 7.0 phosphate buffer solution is -0.02 V (vs. Ag/AgCl). The analytical performance of the biosensor prepared from C₁₈-PdNPs-GOx is better than that of C₁₂-PdNPs-GOx. The C₁₈-PdNPs-GOx/GC biosensor exhibits a fast response time of ca. 3s, a detection limit of 3.0 μM (S/N=3) and a linear range of 3.0 μM-8.0 mM. The linear dependence of current density with glucose concentration is 70.8 μA cm⁻² mM⁻¹. The biosensor shows good stability, repeatability and reproducibility. It has been successfully applied to determine the glucose content in human blood serum samples.
Biosensors & bioelectronics 07/2011; 26(11):4619-23. · 5.43 Impact Factor
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ABSTRACT: A simple and relatively cheap glucose biosensor based on a combination of gold nanoparticles (Au NPs) and glucose oxidase (GO(x) ) immobilized on a bioplatform eggshell membrane was established. Scanning electron microscopy showed successful immobilization of Au NPs/GO(x) on the eggshell membrane. The effects of pH, phosphate buffer concentration, and temperature on the glucose biosensor were studied in detail. The biosensor shows a linear response at a glucose concentration range of 5-525 μM. The detection limit of the biosensor is 2.5 μM (S/N = 3). The biosensor exhibits good repeatability with RSD = 3.6% (n = 6), good operational stability with over 300 measurements and long-term storage stability with a shelf life of at least 6 months. The response time is less than 60 s. The glucose level in commercial food samples has been successfully determined. The proposed work shows potential to develop cost-effective biosensors for biotechnological, biomedical and industrial use.
Biotechnology Journal 03/2011; 6(5):492-500.
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ABSTRACT: Naproxen enantiomers possess strong room temperature phosphorescence (RTP) in β-cyclodextrin (β-CD) system with a small amount of 1,2-dibromoethane (1,2-DBE) under ambient conditions. The effects of pH, concentration of β-CD, and 1,2-DBE on the RTP of naproxen enantiomers have been investigated in detail. Time-resolved RTP spectroscopy shows that both naproxen enantiomers exhibit biexponential decay pattern with lifetimes of τ1 = 4.79 ± 0.13 and τ2 = 1.51 ± 0.096 ms for R-naproxen and τ1 = 6.67 ± 0.15 and τ2 = 2.13 ± 0.061 ms for S-naproxen. The lifetime differences between these enantiomers are Δτ1 = 1.88 and Δτ2 = 0.62 ms, indicating that chiral discrimination of naproxen enantiomers can be achieved in β-CD/1,2-DBE system. Naproxen enantiomers can form stable complexes with β-CD and 1,2-DBE in stoichiometric ratios of 1:1:2 and 1:1:1 (naproxen:β-CD:1,2-DBE), and the association constants are 3.20 × 103 M−4 and 2.43 × 103 M−3 for the S- and R-enantiomers, respectively. The chiral discrimination of R-naproxen and S-naproxen is realized via their difference in interaction with the chiral cavity of β-CD due to their difference in stereochemical structure. Finally, molecular modeling is performed to determine the chiral recognition on a molecular level, and the results are in good agreement with the experimental data.
02/2011;
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ABSTRACT: Cadmium (Cd) is an environmental pollutant and has been found to pose a potential threat to human health. Isoquercitrin (IQ) is one of the most important flavonoids and has been demonstrated to exhibit potent antioxidant effects on plants and yeast cells. However, only few studies have investigated the antioxidative activities of reactive oxygen species (ROS) and the nitrite scavenging activities of IQ against Cd-induced oxidation in mouse. The present work was to investigate the ROS and nitrite-scavenging activities of IQ in vitro as well as its preventive effects against lipid peroxidation and protein oxidative damage in liver and kidney of mouse induced by Cd(²+) using spectrophotometry. Our results showed that IQ possesses scavenging abilities for superoxide anion, hydroxyl radical and nitrite. Such scavenging capacities increase with the concentration of IQ. Moreover, cadmium chloride (CdCl₂ (2.5 mg/kg body weight, i.p. CdCl₂) significantly inhibited the activities of superoxide dismutase and catalase and raised the levels of malondialdehyde, nitric oxide, protein carbonyl, and the coefficients of DNA-protein crosslinks in livers and/or kidneys of mice. IQ attenuated the Cd(²+)-induced biochemical alterations in the livers and/or kidneys of mice, indicating that the formation of ROS and nitrite is possibly reduced. Our work demonstrates that IQ possesses ROS and nitrite-scavenging capacities and plays a significant role in combating Cd(²+)-induced toxicity in animals.
Archiv für Experimentelle Pathologie und Pharmakologie 02/2011; 383(5):437-45. · 2.65 Impact Factor
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ABSTRACT: Upon addition of a small amount of bromocyclohexane, propranolol displays room temperature phosphorescence in γ-cyclodextrin solution without deoxygenation. Several factors including the pH, and the concentration of γ-cyclodextrin and bromocyclohexane, which affect the room temperature phosphorescence (RTP) intensity and room temperature phosphorescence lifetime of propranolol are studied in detail. Under optimal conditions, the room temperature phosphorescence lifetimes of propranolol enantiomers are measured. The experimental results show that the associated phosphorescence decay curves can be best fitted to mono-exponential patterns and room temperature phosphorescence lifetimes of R- and S-propranolol are 4.60 ms and 5.74 ms, respectively. The difference of the room temperature phosphorescence lifetimes of R- and S-propranolol is 22.05%. Based on that, chiral discrimination of propranolol enantiomers is carried out successfully by time-resolved phosphorescence.
The Analyst 11/2010; 136(2):299-303. · 4.23 Impact Factor
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ABSTRACT: The interactions of brilliant cresyl violet (BCV) with herring sperm DNA in gamma-cyclodextrin (gamma-CD) supramolecular system were studied by UV-vis absorption spectroscopy and cyclic voltammetry (CV). Both UV-vis absorption and CV data show that the interaction of BCV with DNA depends on the concentration ratio of BCV to DNA (R), the initial concentration of BCV and gamma-CD. The binding constants of BCV monomer, (BCV)(2) dimer and (BCV)(2)-gamma-CD inclusion complex with DNA are 1.64x10(5), 2.56x10(4) and 2.32x10(3) M(-1), respectively. It was observed that gamma-CD can affect the interactive mode of BCV with DNA. If R is larger than 0.5, the (BCV)(2)-gamma-CD inclusion complex will retain intact and bind to DNA via the electrostatic attraction forces. By contrast, when R is smaller than 0.5, the inclusion complex will be partially dissociated and the free BCV monomer is intercalated into the double-helix structure of DNA attributing to the more favorable microenvironment of DNA for the BCV monomer. Our work postulates the importance of the initial concentration of dye and host molecule on the interaction of dye with DNA in living bodies.
Talanta 07/2010; 82(2):681-6. · 3.79 Impact Factor
