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A generic approach based on long-lifetime fluorophores for the assessment of protein binding to polymer nanoparticles by fluorescence anisotropy. NANOSCALE 2024; 16:3659-3667. [PMID: 38287773 DOI: 10.1039/d3nr02460a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
Quantitation of protein-nanoparticle interactions is essential for the investigation of the protein corona around NPs in vivo and when using synthetic polymer nanoparticles as affinity reagents for selective protein recognition in vitro. Here, a method based on steady-state fluorescence anisotropy measurement is presented as a novel, separation-free tool for the assessment of protein-nanoparticle interactions. For this purpose, a long-lifetime luminescent Ru-complex is used for protein labelling, which exhibits low anisotropy when conjugated to the protein but displays high anisotropy when the proteins are bound to the much larger polymer nanoparticles. As a proof of concept, the interaction of lysozyme with poly(N-isopropylacrylamide-co-N-tert-butylacrylamide-co-acrylic acid) nanoparticles is studied, and fluorescence anisotropy measurements are used to establish the binding kinetics, binding isotherm and a competitive binding assay.
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Complexes of carboxylato pillar[6]arene with Brooker-type merocyanines: Spectral properties, pK a shifts and the design of a displacement assay for trimethyl lysine. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 252:119455. [PMID: 33515854 DOI: 10.1016/j.saa.2021.119455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/05/2021] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
The supramolecular complexes of three strongly solvatochromic dyes, Brooker's merocyanine (M1) and its two derivatives (M2, M3) with carboxylato pillar[6]arene (WP6) were studied in aqueous solutions. The dye-WP6 mixtures were described in terms of four equilibrium reactions: the acidic dissociations of the pyridinium phenols into the zwitterionic phenolates, the acidic dissociations of the complexed phenols, the bindings of the phenol form dyes to WP6 and the bindings of the phenolates to WP6. The equilibrium constants were determined by an analysis of the absorption spectra. It was found that the acidity of the phenol form merocyanines were largely reduced on complexation, pKa shifts of 1.1-1.6 units were observed. In neutral solutions, the complexes of the phenol forms of M1 and M2 were dominant, in contrast to the more acidic M3 (a dibromo derivative), of which the phenolate complex was more stable. Comparing the spectral properties, the binding constants and the pKa-s of the dye-WP6 complexes, the complex M3⋅WP6 was chosen to be tested as a displacement assay. It was demonstrated that this complex functioned as a colorimetric indicator displacement assay which discriminated trimethyl lysine from other lysine derivatives.
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Binding Modes of a Phenylpyridinium Styryl Fluorescent Dye with Cucurbiturils. Molecules 2020; 25:E5111. [PMID: 33153219 PMCID: PMC7663148 DOI: 10.3390/molecules25215111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 11/16/2022] Open
Abstract
In order to explore how cucurbituril hosts accommodate an N-phenyl-pyridinium derivative guest, the complexation of the solvatochromic dye, 4-(4-(dimethylamino)styryl)-1-phenylpyridinium iodide (PhSt) with ,',δ,δ'-tetramethyl-cucurbit[6]uril (Me4CB6) and cucurbit[7]uril (CB7) was investigated by absorption spectroscopic, fluorescence and NMR experiments. In aqueous solutions, PhSt forms 1:1 complexes with both cucurbiturils, the complex with CB7 has a higher stability constant (Ka = 6.0 × 106 M-1) than the complex with Me4CB6 (Ka = 1.1 × 106 M-1). As revealed by NMR experiments and confirmed by theoretical calculations, CB7 encapsulates the whole phenylpyridinium entity of the PhSt cation guest, whereas the cavity of Me4CB6 includes only the phenyl ring, the pyridinium ring is bound to the carbonyl rim of the host. The binding of PhSt to cucurbiturils is accompanied by a strong enhancement of the fluorescence quantum yield due to the blocking of the deactivation through a twisted intramolecular charge transfer (TICT) state. The TICT mechanism in PhSt was characterized by fluorescence experiments in polyethylene glycol (PEG) solvents of different viscosities. The PhSt-CB7 system was tested as a fluorescence indicator displacement (FID) assay, and it recognized trimethyl-lysine selectively over other lysine derivatives.
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Strong ion pair charge transfer interaction of 1,8-naphthalimide–bipyridinium conjugates with basic anions – towards the development of a new type of turn-on fluorescent anion sensors. NEW J CHEM 2019. [DOI: 10.1039/c9nj00382g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluoride, acetate and benzoate anions reduce naphthalimide–viologen dyads into radicals, which is indicated by a strong fluorescence enhancement.
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Carboxylato-pillar[6]arene-based fluorescent indicator displacement assays for the recognition of monoamine neurotransmitters. RSC Adv 2019; 9:16856-16862. [PMID: 35516407 PMCID: PMC9064442 DOI: 10.1039/c9ra03241j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 05/19/2019] [Indexed: 11/30/2022] Open
Abstract
The complexation of three cationic fluorescent dye guests with the anionic host carboxylato-pillar[6]arene (WP6) was investigated by optical and NMR spectroscopy. Among the selected indicators – a stilbazolium dye (i1) and two naphthalimide derivatives with positively charged ‘anchor’ groups (i2 and i3) – i1 gave a large turn-on, i2 and i3 a large turn-off fluorescence response to the complexation. The size selectivity of the complex formation of pillararenes was demonstrated by comparing the binding constants of the complexes of the three indicators with WP6 and its smaller homologue, WP5. The systems WP6·i1 and WP6·i2 were tested as indicator displacement assays for the sensing of monoamine neurotransmitters. The WP6·i1 system functioned as a turn-off, the WP6·i2 system as a turn-on sensor for neurotransmitters, and both assays showed a good selectivity to histamine over the other neurotransmitter analytes. The complexation of three cationic fluorescent dye guests with the anionic host carboxylato-pillar[6]arene (WP6) was investigated by optical and NMR spectroscopy.![]()
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Hydrogen bonding effects on the fluorescence properties of 4'-diethylamino-3-hydroxyflavone in water and water-acetone mixtures. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 203:96-105. [PMID: 29860173 DOI: 10.1016/j.saa.2018.05.104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 05/21/2018] [Accepted: 05/27/2018] [Indexed: 06/08/2023]
Abstract
The fluorescence properties of 4'-diethylamino-3-hydroxyflavone (FET), a dye probe sensitive to the polarity as well as the hydrogen bonding ability of its environment, have been studied in acetone-water mixtures by measuring spectra and decay curves over the whole composition range and analyzing the results on the basis of theoretical calculations. In acetone, like in most of organic solvents, the dye showed dual fluorescence, due to an excited state intramolecular proton transfer (ESIPT), in which a quasi-equilibrium between the two excited species, N* and T*, was reached. In acetone-water mixtures with lower molar fractions of water, where the water molecules are largely dispersed, only one type of hydrate could be detected, a complex with 1:1 composition, showing only N* emission, but with a high (0.45) fluorescence quantum yield. At higher water concentrations, the interaction of FET with the hydrogen-bonded water clusters resulted in fluorescence quenching. In neat water the fluorescence quantum yield fell to ~0.001. Theoretical calculations on a FET-acetone complex, a FET-water complex and a FET-water-acetone triple complex (the latter as model for the samples with low water concentrations) concluded that ESIPT was energetically favored in all the models, but the E(N*)-E(T*) energy difference for the water complexes was much lower. The kinetic barrier of ESIPT was found greatly higher in the FET-water complex than in the isolated solute. The intermolecular hydrogen bonds in the water complexes became significantly stronger following the excitation, stabilizing the N* form of the hydrated dye.
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An uracil-linked hydroxyflavone probe for the recognition of ATP. Beilstein J Org Chem 2018; 14:747-755. [PMID: 29719572 PMCID: PMC5905274 DOI: 10.3762/bjoc.14.63] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 03/13/2018] [Indexed: 01/05/2023] Open
Abstract
Background: Nucleotides are essential molecules in living systems due to their paramount importance in various physiological processes. In the past years, numerous attempts were made to selectively recognize and detect these analytes, especially ATP using small-molecule fluorescent chemosensors. Despite the various solutions, the selective detection of ATP is still challenging due to the structural similarity of various nucleotides. In this paper, we report the conjugation of a uracil nucleobase to the known 4'-dimethylamino-hydroxyflavone fluorophore. Results: The complexation of this scaffold with ATP is already known. The complex is held together by stacking and electrostatic interactions. To achieve multi-point recognition, we designed the uracil-appended version of this probe to include complementary base-pairing interactions. The theoretical calculations revealed the availability of multiple complex structures. The synthesis was performed using click chemistry and the nucleotide recognition properties of the probe were evaluated using fluorescence spectroscopy. Conclusions: The first, uracil-containing fluorescent ATP probe based on a hydroxyflavone fluorophore was synthesized and evaluated. A selective complexation with ATP was observed and a ratiometric response in the excitation spectrum.
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Preparation of enantiopure 1-isopentyl-3-methyl-3-phospholene 1-oxide via the formation of diastereomeric complexes. HETEROATOM CHEMISTRY 2018. [DOI: 10.1002/hc.21411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Experimental evidence of TICT state in 4-piperidinyl-1,8-naphthalimide – a kinetic and mechanistic study. Phys Chem Chem Phys 2018; 20:10155-10164. [DOI: 10.1039/c7cp08555a] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The excited state processes in N-propyl-4-piperidinyl-1,8-naphthalimide have been studied by measuring its fluorescence spectra and decay curves in solvents of different polarity and viscosity and also in a frozen solvent glass.
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Theoretical study on the photooxygenation and photorearrangement reactions of 3-hydroxyflavone. RSC Adv 2017. [DOI: 10.1039/c7ra04590e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The mechanisms of three photodegradation reactions of 3-hydroxyflavone – its photosensitized oxygenation, photooxygenation with 3O2 and photorearrangement into an indanedione derivative – have been investigated by computing the free energy profiles.
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Crown ether derived from d-glucose as an efficient phase-transfer catalyst for the enantioselective Michael addition of malonates to enones. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.tetasy.2016.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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13
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Synthesis, Characterization, and Application of Platinum(II) Complexes Incorporating Racemic and Optically Active 4-Chloro-5-Methyl-1-Phenyl-1,2,3,6-Tetrahydrophosphinine Ligand. HETEROATOM CHEMISTRY 2016. [DOI: 10.1002/hc.21305] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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The kinetics and mechanism of photooxygenation of 4'-diethylamino-3-hydroxyflavone. Photochem Photobiol Sci 2016; 15:219-27. [PMID: 26738442 DOI: 10.1039/c5pp00358j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photolysis reactions of 4'-diethylamino-3-hydroxyflavone (D), a versatile fluorescent probe showing excited-state intramolecular proton transfer (ESIPT), and the magnesium chelate of D (MgD(2+)) have been studied in acetonitrile solution. Upon UV irradiation both species were oxidized into O-4-diethylaminobenzoyl salicylic acid, differently from the photoreaction of the parent compound 3-hydroxyflavone (3HF) which was described to undergo rearrangement to 3-hydroxy-3-phenyl-indan-1,2-dione. The photooxygenation of the Mg(2+) complex was found to be significantly faster than the reaction of the pure dye. As the kinetic analysis of the absorption spectra of samples under irradiation showed, the rate coefficients for the oxygenations of the excited state dye and complex have close values, kox(D*) = 2.4 × 10(7) min(-1), kox(MgD(2+)*) = 3.9 × 10(7) min(-1); the difference arises from the higher photooxygenation quantum yield of the complex, Φ(MgD(2+)) = 2.3 × 10(-3), than the respective value for the pure dye, Φ(D) = 1.5 × 10(-4). The potential energy surface of the photooxygenation of D was calculated assuming a reaction path in which the phototautomer formed from Dvia ESIPT, reacts in its triplet state with triplet molecular oxygen O2, a mechanism similar to that suggested for the photoreaction of the parent 3HF. The moderate values for the transition state energies confirmed the plausibility of the hypothetical mechanism.
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Amino acid recognition by fine tuning the association constants: tailored naphthalimides in pillar[5]arene-based indicator displacement assays. RSC Adv 2016. [DOI: 10.1039/c6ra15003a] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Three naphthalimide derivatives were synthesized with different anchoring groups to adjust the supramolecular interactions with carboxylato-pillar[5]arene. The complexes were used as indicator displacement assays for basic amino acids and diamines.
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16
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Optical spectroscopic studies on the complexation of stilbazolium dyes with a water soluble pillar[5]arene. RSC Adv 2015. [DOI: 10.1039/c4ra14809f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The host–guest interactions of carboxylato-pillar[5]arene (WPA5) and three stilbazolium dyes were studied by optical spectroscopy. A fluorescence indicator displacement based on WPA5 was shown to detect paraquat in aqueous solution.
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A Case Study on the Resolution of the 1-i-Butyl-3-methyl-3-phospholene 1-Oxide via Diastereomeric Complex Formation Using TADDOL Derivatives and via Diastereomeric Coordination Complexes Formed from the Calcium Salts ofO,O′-Diaroyl-(2R,3R)-tartaric Acids. HETEROATOM CHEMISTRY 2014. [DOI: 10.1002/hc.21218] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Solvation and protonation of coumarin 102 in aqueous media: a fluorescence spectroscopic and theoretical study. J Phys Chem A 2014; 118:5238-47. [PMID: 24945906 DOI: 10.1021/jp504496k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ground- and excited-state protonation of Coumarin 102 (C102), a fluorescent probe applied frequently in heterogeneous systems with an aqueous phase, has been studied in aqueous solutions by spectroscopic experiments and theoretical calculations. For the dissociation constant of the protonated form in the ground state, pKa = 1.61 was obtained from the absorption spectra; for the excited-state dissociation constant, pKa* = 2.19 was obtained from the fluorescence spectra. These values were closely reproduced by theoretical calculations via a thermodynamic cycle (the value of pKa* also by calculations via the Förster cycle) using an implicit–explicit solvation model (polarized continuum model + addition of a solvent molecule). The theoretical calculations indicated that (i) in the ground state, C102 occurs primarily as a hydrogen-bonded water complex, with the oxo group as the binding site, (ii) this hydrogen bond becomes stronger upon excitation, and (iii) in the ground state, the amino nitrogen atom is the protonation site, and in the excited state, the carboxy oxygen atom is the protonation site. A comprehensive analysis of fluorescence decay data yielded the values kpr = 3.27 × 10(10) M(–1) s(–1) for the rate constant of the excited-state protonation and kdpr = 2.78 × 10(8) s(–1) for the rate constant of the reverse process (kpr and kdpr were treated as independent parameters). This, considering the relatively long fluorescence lifetimes of neutral C102 (6.02 ns) and its protonated form (3.06 ns) in aqueous media, means that a quasi-equilibrium state of excited-state proton transfer is reached in strongly acidic solutions.
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Resolution of 1-n-butyl-3-methyl-3-phospholene 1-oxide with TADDOL derivatives and calcium salts of O,O'-Dibenzoyl-(2R,3R)- or O,O'-di-p-toluoyl-(2R,3R)-tartaric acid. Chirality 2014; 26:174-82. [PMID: 24510520 DOI: 10.1002/chir.22293] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 11/27/2013] [Accepted: 12/09/2013] [Indexed: 11/06/2022]
Abstract
The resolution methods applying (-)-(4R,5R)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane ("TADDOL"), (-)-(2R,3R)-α,α,α',α'-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol ("spiro-TADDOL"), as well as the acidic and neutral Ca(2+) salts of (-)-O,O'-dibenzoyl- and (-)-O,O'-di-p-toluoyl-(2R,3R)-tartaric acid were extended for the preparation of 1-n-butyl-3-methyl-3-phospholene 1-oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single-crystal X-ray analysis. The absolute P-configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra.
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Resolution of 1-n-propoxy-3-methyl-3-phospholene 1-oxide by diastereomeric complex formation using TADDOL derivatives and calcium salts of O,O′-dibenzoyl-(2R,3R)- or O,O′-di-p-toluoyl-(2R,3R)-tartaric acid. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.tetasy.2014.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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Synthesis of atropisomeric 1-phenylpyrrole-derived amino alcohols: New chiral ligands. Chirality 2012; 24:532-42. [DOI: 10.1002/chir.22049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/11/2012] [Indexed: 11/11/2022]
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22
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Synthesis and metal ion complexation of spin labeled 18-crown-6 ethers containing an acridone or an acridine fluorophore unit. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.09.092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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23
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Metal complexes of the merocyanine form of nitrobenzospyran: Structure, optical spectra, stability. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2011.05.055] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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24
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Synthesis and enantiomeric recognition studies of dialkyl-substituted 18-crown-6 ethers containing an acridine fluorophore unit. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.tetasy.2011.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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25
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BINOL-based azacrown ether catalyzed enantioselective Michael addition: asymmetric synthesis of α-aminophosphonates. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.tetasy.2011.02.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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26
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Synthesis and optical resolution of 1-[(3-carboxy-1,1′-biphenyl)-2-yl]-1H-pyrrole-2-carboxylic acid. Chirality 2009. [DOI: 10.1002/chir.20686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Efficient synthesis of optically active 1-(2-carboxymethyl-6-ethylphenyl)-1H-pyrrole-2-carboxylic acid: a novel atropisomeric 1-arylpyrrole derivative. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.tetasy.2009.01.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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28
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Spectroscopy of laser-induced carbon plasma with nanosecond time resolution. PERIODICA POLYTECHNICA-CHEMICAL ENGINEERING 2009. [DOI: 10.3311/pp.ch.2009-2.05] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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29
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Synthesis, optical and electroanalytical characterizations of a thiacalix[4](N-phenylazacrown-5)ether–BODIPY ionophore. Tetrahedron 2008. [DOI: 10.1016/j.tet.2007.06.116] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Efficient singlet-state deactivation of cyano-substituted indolines in protic solvents via CN--HO hydrogen bonds. Chemphyschem 2008; 8:2627-35. [PMID: 18058777 DOI: 10.1002/cphc.200700479] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The photophysical properties of indoline (I) and three of its derivatives, namely, N-methylindoline (MI), 5-cyanoindoline (CI), and 5-cyano-N-methylindoline (CMI), are studied in H-donating solvents of varying polarity. Based on measurements of fluorescence yield and lifetime, and of triplet yield and hydrated-electron formation, two distinct mechanisms of solvent-induced fluorescence quenching are evidenced. The first mechanism involves the cyano substituent and leads to an increase in the rate constant of internal conversion of one order of magnitude in ethanolic solution and of more than two orders of magnitude in water, as compared to solutions in n-hexane or acetonitrile. A similar trend had previously been observed in the case of 4-N,N-dimethylaminobenzonitrile (DMABN). The second mechanism reduces the fluorescence lifetimes of the non-cyanated derivatives in aqueous solution by one order of magnitude and is related to the formation of hydrated electrons. Neither of these mechanisms is influenced by methylation at the ring nitrogen. Quantum chemical calculations are performed on the ground and excited states of the hydrogen-bonded complexes between protic solvents and MI as well as CMI. Stable hydrogen-bonded configurations involving the CN substituent and a solvent OH group are found; these configurations are stable both in the ground and the first excited singlet states, whereas the corresponding complex at the ring amino nitrogen is stable in the ground state only. The CN--HO configuration is therefore a prime candidate for a mechanistic explanation of the observed quenching by the first mechanism. These findings may have useful applications for the design of fluorescence probes for water in biological systems.
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1H and 7Li NMR Study on the Complex Formation of Lithium Cations with Pyridinium Derivatives of Calix[4]arenes. Supramol Chem 2007. [DOI: 10.1080/10610270410001722015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Femtosecond Studies of Charge-Transfer Mediated Proton Transfer in 2-Butylamino-6-methyl-4-nitropyridine N-Oxide. J Phys Chem A 2006; 110:7086-91. [PMID: 16737257 DOI: 10.1021/jp061409z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have unraveled the effects of an amino substituent in the ortho position on the excited-state dynamics of 4-nitropyridine N-oxide by studying the picosecond fluorescence kinetics and femtosecond transient absorption of a newly synthesized compound, 2-butylamino-6-methyl-4-nitropyridine N-oxide, and by quantum chemical calculations. Similar to the parent compound, the S(1) state of the target molecule has significant charge-transfer character and shows a large (approximately 8000 cm(-1)) static Stokes shift in acetonitrile. Analysis of the experimental and the theoretical results leads, however, to a new scenario in which this intramolecular charge transfer triggers in polar, aprotic solvents an ultrafast (around 100 fs) intramolecular proton transfer between the amino and the N-O group. The electronically excited N-OH tautomer is subsequently subject to solvent relaxation and decays with a lifetime of approximately 150 ps to the ground state.
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35
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Rotational reorientation dynamics of ionic dye solutes in polar solvents with the application of a general model for the solvation shell. Chem Phys 2006. [DOI: 10.1016/j.chemphys.2005.08.070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Synthesis of d-mannose-based azacrown ethers and their application in enantioselective reactions. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.tetasy.2005.03.025] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Absorption and fluorescence spectroscopic study on complexation of Oxazine 1 Dye by calix[8]arenesulfonate. APPLIED SPECTROSCOPY 2005; 59:134-139. [PMID: 15720749 DOI: 10.1366/0003702052940477] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
It has been established by combined absorption and fluorescence measurements that the cationic dye Oxazine 1 (OX) and the polyvalent anionic host calix[8]arenesulfonate (SCA8) form two complexes in simultaneous reactions: OX + SCA8 <--> OX.SCA8 (1), and OX.SCA8 + OX <--> OX(2).SCA8 (2). The equilibrium constants for the two reactions, as functions of the ionic strength (I), and the absorption and fluorescence spectra of the two complex species have been determined by a least-squares fitting method from the experimental data. The variations of the binding constants with the ionic strength could be described on the basis of Debye-Huckel theory. The equilibrium constants are large; their values extrapolated to I = 0 are K(1) = 5.5 x 10(6) M(-1) and K(2) = 4.4 x 10(5) M(-1). The fluorescence of OX undergoes a strong static quenching upon complexation. These results indicate that the complexes are held together by strong electrostatic forces. The addition of non-fluorescent tetramethylammonium chloride to OX-SCA8 mixtures results in a dramatic fluorescent enhancement, which demonstrates the potential applicability of this supramolecular system in fluorescence assays.
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Phase-transfer catalyzed asymmetric epoxidation of chalcones using chiral crown ethers derived from d-glucose, d-galactose, and d-mannitol. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.tetasy.2004.03.029] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Absorption, fluorescence, and cd spectroscopic study of chiral recognition by a binaphthyl-derived chromogenic calixcrown host. Chirality 2004; 16:174-9. [PMID: 14770414 DOI: 10.1002/chir.20003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The (R)- and (S)-enantiomers of a binaphthyl-appended calix[4]crown-6 ether with two 2,4-dinitrophenylazo chromophore units ((R)-1 and (S)-1) as chiral hosts were tested in their reactions with the enantiomers of alpha-methylbenzylamine ((R)-MBA, (S)-MBA)) and phenylglycinol ((R)-PGL, (S)-PGL) as chiral guests. The visible absorption spectra indicate a two-step process: the first is a nonenantioselective proton transfer from the host to the guest, which is followed by the enantioselective real complexation. In the visible range of the CD spectra a positive/negative band belongs to the absorption of pure (R)-1/(S)-1, and a negative/positive exciton couplet to the absorption of (R)-1-(S)-MBA/(S)-1-(R)-MBA complexes. The latter phenomenon suggests that the complexation of amines is accompanied by a chiral arrangement of the two chromophore units in the hosts. The UV fluorescence of (R)-1/(S)-1 arising from the binaphthyl moiety is quenched by K+ ions, but not by the amine guests, showing that the interaction between the binaphthyl group and the complexed amines is weak.
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Spectroscopic study on the complex formation of chromogenic bridged calixarenes with aliphatic amines. J Mol Struct 2003. [DOI: 10.1016/s0022-2860(03)00079-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Synthesis of chiral 1,3-calix[4](crown-6) ethers as potential mediators for asymmetric recognition processes. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0957-4166(03)00174-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Interaction of triplet C60with p-tert-butyl-calixarenes and their complexes with pyridine derivatives. Phys Chem Chem Phys 2003. [DOI: 10.1039/b301633a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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(S)-α,α-Diphenyl- and (S)-α,α-dinaphthyl-2-pyrrolidinemethanol as chiral modifiers in asymmetric heterogeneous catalytic hydrogenation of isophorone. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1381-1169(02)00176-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Proton transfer and supramolecular complex formation between Nile Blue and tetraundecylcalix[4]resorcinarene—a fluorescence spectroscopic study. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b202637f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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A Density Functional, Infrared Linear Dichroism, and Normal Coordinate Study of Phenol and its Deuterated Derivatives: Revised Interpretation of the Vibrational Spectra. J Phys Chem A 1998. [DOI: 10.1021/jp972585y] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Laser spectroscopic study of photoinduced picosecond processes in amorphous and polycrystalline silicon films. J Mol Struct 1997. [DOI: 10.1016/s0022-2860(96)09623-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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