Synthesis and photophysical studies of novel 4-aryl substituted 2-phenyl-, 2-(fluoren-2-yl)- and 2-cymantrenylquinazolines (original) (raw)
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Synthesis and Photophysical Studies of 2-(Thiophen-2-yl)-4- (morpholin-4-yl)quinazoline Derivatives
The synthesis of a series of push–pull aryl and aryl-ethynyl 2-(thiophen-2-yl)quinazoline derivatives is presented. The photophysical properties of the newly generated compounds are also described. Functionalization of the (2-thi-enyl)quinazoline fluorophore at the 5′-position with aryl and arylethynyl moieties was performed using bromination and subsequent palladium-catalyzed cross-coupling reactions. Optical studies revealed that 4-(diethylamino)phenyl and 4-(diphen
Chemistry – An Asian Journal, 2021
2‐N‐aminoquinazolines were prepared by consecutive SNAr functionalization. X‐ray structures display the nitrogen lone pair of the 2‐N‐morpholino group in conjugation with the electron deficient quinazoline core and thus representing electronic push‐pull systems. 2‐N‐aminoquinazolines show a positive solvatochromism and are fluorescent in solution and in solid state with quantum yields up to 0.73. Increase in electron donor strength of the 2‐amino substituent causes a red‐shift of the intramolecular charge transfer (ICT) band (300–400 nm); whereas the photoluminescence emission maxima (350–450 nm) is also red‐shifted significantly along with an enhancement in photoluminescence efficiency. HOMO‐LUMO energies were estimated by a combination of electrochemical and photophysical methods and correlate well to those obtained by computational methods. ICT properties are theoretically attributed to an excitation to Rydberg‐MO in SAC‐CI method, which can be interpreted as n‐π* excitation. 7‐A...
Journal of Chemistry, 2013
A series of novel 2-(1-benzofuran-2-yl)-4-(1,3 benzoxazol-2-yl/1,3-benzothiazol-2-yl) quinoline derivatives 4(a-d) were synthesized in one step by the reaction of 2-(1-benzofuran-2-yl) quinoline-4-carboxylic acids 3(a-b) with o-aminophenol and o-amino thiophenol, respectively, using polyphosphoric acid (PPA) as a cyclizing agent. e �uorescent properties of newly synthesized compounds were investigated in three different organic solvents like chloroform (CHCl 3 ), tetrahydrofuran (THF), and dimethyl sulfoxide (DMSO). e photophysical constants such as quantum yield and stokes shi were determined. From the results of �uorescence study, it is evident that all synthesized compounds are �uorescent in solution. Compound 4a emitted green light (490.4 nm, 518.2 nm, and 522.4 nm) with high quantum yield in all the three solvents, while compounds 4b, 4c, and 4d emitted green light (512 nm, 499 nm, 510 nm) only in polar solvent DMSO. All �uorescent probes exhibited a bathochromic shi on increase in polarity of the solvent.
International Journal of Organic Chemistry, 2012
Novel 3-phenyl/pyridinyl-trans-2-(aryl/heteryl)vinyl-3H-quinazolin-4-ones 3a,b, 4a, 5a, 7a and their 6,7-difluoro derivatives 3c,d, 4b, 5b, 7b have been obtained by condensation of the correspondent 2-methylquinazolin-4-ones 1, 6 with aromatic (heterocyclic) aldehydes in the presence of ZnCl 2 (AcONa) or by the reaction of 2-methyl-3,1-benzoxazin-4ones 2 with the Shiff bases. Effects of aryl(heteryl) substituents on photophysical properties of (aryl/heteryl) quinazolinylethenes have been studied.
ACS Omega
A facile and efficient method has been developed for the synthesis of quinoline-fused fluorescent dihydro/spiroquinazolinones. A plausible mechanism involving an acid-mediated enaminone intermediate is provided. The reaction proceeded using p-toluene sulfonic acid as a green promoter. The methodology was successful in synthesizing various quinoline-appended spiro-quinazolinones 4a−o. The synthetic utility of compounds 4a−o was demonstrated by synthesizing compounds 6a−d via Suzuki coupling as a key reaction. Significantly, the π−π* electronic transition of compounds 4c and 4k showed a blue shift. The molar extinction coefficient (ε), Stoke's shift (Δu ̅), and quantum yield (Φ f) c were calculated for these derivatives (4c and 4k).
Mendeleev Communications, 2018
Arylated 2,4-disubstituted quinazolines are prospective photoluminescent and electroluminescent materials. Among them, donor-quinazoline-donor type containing 4-diethylaminophenyl residue are of special interest. 1 On the other hand, thienyl substituted diazines with extended p-conjugated system exhibit electro chemical, optical and electronic structural properties. 2 Arylamino derivatives, in par ticular N,N-dialkyl-and N,N-diphenylanilines, are electron-rich compounds which find use as hole transporting materials and light emitters. 3 Recently, we reported the functionalization of 2-(thiophen-2-yl)-4-(morpholin-4-yl)quinazoline fluorophore at the 5-position of thiophene ring with aryl and arylethynyl moieties through bromination and subsequent palladium-catalyzed cross-coupling reactions. 4 The thus obtained 2-[5-(4-diethylaminophenyl)thio phen-2-yl]-4-(morpholin-4-yl)quinazoline 1 demonstrated emission of green light upon irradiation and the highest quantum yield. The effect of its protonation has also been studied, and the ability of this molecule to function as colorimetric and luminescent pH sensor has been revealed with significant colour changes and luminescence switching upon the introduction of acid. 4
Tetrahedron, 2016
A series of novel 2-aryl-6-bromo-4-chloro-8-iodoquinazolines were prepared and subjected to sequential two-step (Sonogashira and subsequent one-pot bis-Suzuki) and one-pot three-step Sonogashira cross-coupling reactions to afford unsymmetrical polycarbo-substituted quinazolines. Selectivity in the cross-coupling for these multihalogenated quinazolines was found to depend on both the intrinsic reactivity of the Csp 2-halogen bond, which relates to the bond dissociation energy or bond strength and the electronic position of the halogen atom on the electron deficient scaffold (trend: Csp 2-I > C(4)-Cl > Csp 2-Br). The electronic absorption and emission properties of the prepared polycarbo-substituted quinazolines were evaluated in solution by means of UV-Vis and emission spectroscopy in conjunction with density functional theory (DFT) method.
New Fluorescent Sensors Based on 1H-pyrazolo[3,4-b]quinoline Skeleton
Journal of Fluorescence, 2010
Novel fluorescing dyes 1,3,4-triphenyl-6-(1,4,7, 10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)-1H-pyrazolo [3,4-b]quinoline (K1) and 2-[(2-hydroxyethyl)-(1,3, 4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amino] ethanol (L1) have been synthesized and investigated by the means of steady state and time-resolved fluorescence techniques. These compounds act as sensors for the fluorescence detection of small inorganic cations (lithium, sodium, barium, magnesium and calcium) in solvents of different polarities (THF and acetonitrile). The mechanism, which allows application of these compounds as sensors, is an electron transfer from the electro-donative part of molecule to the acceptor part (fluorophore), which is retarded upon complexation of the electro-donative part by inorganic cations. We found that crown ether-containing compound is very sensitive to the addition of any investigated ions but amino alcohol-containing one exhibits better selectivity to the addition of two-valued cations. Two kinds of the complexes (LM + and L 2 M +) were found in the investigated systems. In addition, the dyes may be used as fluorescence indicators in solvents of lower polarity like tetrahydrofuran.