Synthesis and Spectral Characteristics of Novel Fluorescent Dyes Based on Pyrimido[4,5-d] [1,2,4]triazolo[4,3-a]pyrimidine (original) (raw)
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Fluorescent property of 3-hydroxymethyl imidazo[1,2-a]pyridine and pyrimidine derivatives
Chemistry Central Journal, 2012
Background Imidazo[1,2-a]pyridines and pyrimidines are important organic fluorophores which have been investigated as biomarkers and photochemical sensors. The effect on the luminescent property by substituents in the heterocycle and phenyl rings, have been studied as well. In this investigation, series of 3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines were synthesized and evaluated in relation to fluorescence emission, based upon the hypothesis that the hydroxymethyl group may act as an enhancer of fluorescence intensity. Results Compounds of both series emitted light in organic solvents dilutions as well as in acidic and alkaline media. Quantitative fluorescence spectroscopy determined that both fused heterocycles fluoresced more intensely than the parent unsubstituted imidazo[1,2-a]azine fluorophore. In particular, 3-hydroxymethyl imidazo[1,2-a]pyridines fluoresced more intensely than 3-hydroxymethyl imidazo[1,2-a]pyrimidines, the latter emitting blue light at longer wav...
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
A novel 4-(morpholinomethyl)-5-oxo-1-phenylpyrrolidine-3-carboxylic acid has been synthesized and its structural elucidation has been done by UV, FT-IR, 1 H and 13 C NMR spectroscopy. All quantum chemical calculations were carried out at level of density functional theory (DFT) with B3LYP function using 6-31G (d, p) basis atomic set. AIM approach has been incorporated for the analysis of various intermolecular interactions. Polarizability and hyperpolarizabilities values have been calculated along with the exploration of nonlinear optical properties of the title compound. DFT computed total first static hyperpolarizability (β 0 = 0.2747×10-30 esu) indicates that title molecule could be an area of interest as an attractive future NLO material. For the analysis of thermal behaviour of title molecule, thermodynamic properties such as heat capacity, entropy and enthalpy change at various temperatures have been calculated. The NBO computations were done for the correlation of possible transitions with the electronic transitions. Electrophilic and nucleophilic regions were identified with the help of MESP plot. Determination of energy gap has been done by using HOMO and LUMO energy values, along with the computation of electronegativity and electrophilicity indices.
Synthesis and fluorescence of new 3-biphenylpyrrolo[1,2-c]pyrimidines
Arabian Journal of Chemistry, 2017
New pyrrolo[1,2-c]pyrimidines derivates having a biphenyl moiety at position 3 have been synthesized by 1,3-dipolar cycloaddition of their corresponding N-ylides with activated alkynes. FTIR, 1 H and 13 C NMR spectroscopy and elemental analysis have been used to characterize the structures of the new nine pyrrolo[1,2-c]pyrimidine derivates. Absorption and fluorescence spectra have been recorded. The appropriate solvent for the photoluminescence properties of the studied compounds has been found to be chloroform:acetonitrile mixture (1:1). The main spectral features such as molar extinction coefficients (e), Stokes shifts, quantum yields using quinine sulphate as standard, fluorescence quenching in the presence of benzoquinone and Stern-Volmer constants have been calculated. The substituent effects on intensity of absorption, maximum absorbance wavelengths and fluorescence parameters have been discussed. The highest quantum yield value was found for ethyl 3-(4-biphenylyl)-7-(3,4-dimethoxybenzoyl)pyrrolo[1,2-c]pyrimidine-5-carboxylate (0.55). The obtained results suggest that the studied compounds are promising candidates for future study in order to evaluate their use in practical applications in fluorescent chemical sensors.
International Journal of Advanced Research in Science, Engineering and Technology, 2018
Cyanine dyes of Zero/monomethine based on N-Bridgehead pyrazolo[4',3':3,4]pyrido[1,2-c]pyrido[1,2- a]pyrimidine heterocycle synthesized and characterized using quaternary salt precursor namely 3,5-dimethyl-12-oxo-1- phenyl-1,12-dihydropyrazolo[4',3':3,4]pyrido[1,2-c]pyrido[1,2-a]pyrimidin-6-ium chloride(24).Such Heterocyclic precursors and related dyes were identified by elemental and spectral analysis. The absorption and emission spectra properties of such dyes were investigated in 95% Ethanol to attempt and throw some light on the influence of such new heterocyclic nuclei and to compare or evaluate spectral behaviors. The Acid-Base properties (halochromism) in aqueous solutions universal buffer of some selected cyanine dyes were studied to determine the better pH for these photosensitizers
Dyes and Pigments, 2019
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Journal of fluorescence, 2015
Novel donor-π-acceptor dyes bearing the pyrimidine unit as an electron-withdrawing group have been synthesized by using combination of two processes, based on the microwave-assisted Suzuki cross-coupling reaction and nucleophilic aromatic substitution of hydrogen. Spectral properties of the obtained dyes in six aprotic solvents of various polarities have been studied by ultraviolet-visible and fluorescence spectroscopy. In contrast to the absorption spectra, fluorescence emission spectra displayed a strong dependence from their solvent polarities. The nature of the observed long wavelength maxima has been elucidated by means of quantum chemical calculations. The electrochemical properties of these dyes have been investigated by using cyclic voltammetry, while their photovoltaic performance was evaluated by a device fabrication study. The experimental and calculation data show that all of the dyes can be regarded as potentially good photosensitizers for dye-sensitized solar cells.
Dyes and Pigments, 2010
The syntheses and fluorescence properties of novel derivatives of pyrido[2 0 ,1 0 :2,3]imidazo[4,5-b]quinoline are described. The key intermediates (4-substituted)(3-hydroxyimino-2,3-dihydroimidazo[1,2-a] pyridin-2-yliden)methyl cyanides were synthesized by reacting the imidazo[1,2-a]pyridine with arylacetonitriles via nucleophilic substitution of hydrogen. The compounds were deep violet in colour. Acylation of hydroxyl group led to heterocyclization and gave highly fluorescent pyrido[2 0 ,1 0 :2,3]imidazo [4,5-b]quinoline. Ó
Tetrahedron Letters, 2006
Two series of compounds, 3-aryl-(series A, compounds 2a-j) and 3-methyl-7-aryl-[1,2,3]triazolo[1,5-a]pyridines (series B, compounds 3a-j) have been synthesized by Suzuki cross-coupling reactions, with a triazolopyridine halide and an aryl or heteroaryl boronic acid in moderate to good yields. All compounds obtained are fluorescents, the quantum yields, particularly those of compounds 3f-j, are very high.
Journal of Luminescence, 2017
A library of fluorescent molecular rotors (FMRs) were synthesised by condensation of 2chloroimidazo[1,2-a]pyridine-3-carbaldehyde with various active methylene moieties and their viscosity sensing properties were studied. The substituted 2-chloroimidazo[1,2a]pyridine-3-carbaldehydes were prepared by a multistep reaction starting from 2aminopyridine or 5-methyl-2-aminopyridine. Substitution of styryl group at the third position of imidazo[1,2-a]pridine ring, the lone pair of bridging nitrogen as well as hyperconjugated methyl group are in proper resonance within the molecule and sustain aromaticity in ring leading to the red shifted absorption. Large red shifted absorptions were observed after substituting electron withdrawing group at the third position as compared to the known 7-[(E)-2-(phenyl)vinyl]-2-phenylimidazo[1,2-a]pyridine analogues where the styryl groups are at the second position of imidazo[1,2-a]pyridines ring. These donor-π-acceptor extended styryl FMRs were investigated for their viscosity sensitivity and found to show values between 0.2135 and 0.5356 in glycerol-methanol system using fluorescence emission spectra. These low molecular weight FMRs are found to show up to 31 fold enhancement in emission 2 intensity in viscous environment. Oscillator strengths (f) and transition dipole moments (µ eg) have been studied to understand charge transfer within the molecules. The structures are confirmed by H 1 NMR, 13C NMR, Mass and elemental analysis.