Chemija ir cheminė technologija

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Karbociklinių ir makrociklinių junginių sintezės principai bei metodai : organinės sintezės metodai : mokomoji knyga

Vytauto Didžiojo universitetasŠvietimo akademij

Synthesis of novel pyrimido[5,4-f][1,2,4]triazolo[3,4-b][1,3,4]thiadiazepines

Reaction of 4,6-dichloro-2-methylthiopyrimidine-5-carbaldehyde (1) with 3-substituted 4-amino-1,2,4-triazole-5-thiones (2a-g) at 50-60degreesC led to 7-chloro-9-methylthiopyrimido[5,4-f][1,2,4]triazolo[3,4-b][1,3,4]thiadiazepines (3a-g) representing a new heterocyclic system. Performing of the reaction of I with 4-amino-1,2,4-triazole-5-thione (La) at room temperature gave 7-chloro-9-methylthio-5,6-dihydropyrimido[5,4-f][1,2,4]triazolo[3,4-b][1,3,4]thiadiazepin-6-oI (5), which with equimolar amount of sodium methoxide afforded 7-methoxy-9-methylthiopyrimido[5,4-f][1,2,4]triazolo[3,4-b][1,3,4]thiadiazepine (6)..

Respublikinės studentų mokslinės konferencijos "Chemija ir cheminė technologija 2019" pranešimų medžiaga

Scientific Committee:Prof. A. Beganskienė, VUDoc./Assoc. Prof. J. Dodonova, VUProf. V. Getautis, KTUProf. S. Grigalevičius, KTUDoc./Assoc. Prof. T. Paulauskienė, KUProf. S. Tumkevičius, VUProf. A. Žukauskaitė, KU Organizers:Prof. S. Tumkevičius (Chairman), VUG. Inkrataitė (secretary), VUDr. R. Vaitkus, VUDr. S. Višniakova, VUI. Gabriūnaitė, VUL. Sinušaitė, VUM. Steponavičiūtė, VUM. Vagner, VUO. Safinas, VU SAL. Daumantas, VUMokslo komitetas:Prof. A. Beganskienė, VUDoc./Assoc. Prof. J. Dodonova, VUProf. V. Getautis, KTUProf. S. Grigalevičius, KTUDoc./Assoc. Prof. T. Paulauskienė, KUProf. S. Tumkevičius, VUProf. A. Žukauskaitė, KU Organizatoriai:Prof. S. Tumkevičius (pirmininkas), VUG. Inkrataitė (sekretorė), VUDr. R. Vaitkus, VUDr. S. Višniakova, VUI. Gabriūnaitė, VUL. Sinušaitė, VUM. Steponavičiūtė, VUM. Vagner, VUO. Safinas, VU SAL. Daumantas, V

Synthesis of 4,6-disubstituted thieno[2,3-d]pyrimidines from 4,6-dichloro-2-methylthiopyrimidine-5-carbaldehyde

Treatment of 4,6-dichloro-2-methylthiopyrimidine-5-carbaldehyde (1) with (1H-benzimidazol-2-yl)methanethiol afforded 6-(1H-benzimidazol-2-yl)-4-chloro-2-methylthiothieno[2,3-d]pyrimidine (g). Reaction of 1 with ethyl mercaptoacetate depending on its amount gave ethyl (4-chloro-2-methylthio-5-formylpyrimidin-6- ylthio)acetate (4) or 4,6-bis(ethoxycarbonylmethylthio)pyrimidine-5-carbaldehyde (g). Heating 4, in dimethyl sulfoxide or ethanol in the presence of base afforded ethyl 4-oxo-3,4-dihydro- (6) and 4-ethoxycarbonylmethylthiothieno[2,3-d]pyrimidine-6-carboxylates(7), respectively..

Synthesis, configuration and isomerization of ethyl 3-substituted 2-cyano-2-propenoates

Vytauto Didžiojo universitetasŠvietimo akademij

Pakaitų įtaka 5-pakeistų 2-pirimidinkarboksirūgščių arilidenhidrazidų ir jų aromatinių analogų amidinės ir azometininės grupių protonų cheminiams poslinkiams

Ištirta pakaitų elektroninių efektų įtaka keturių serijų junginių - 5-pakeistų 2-pirimidinkarboksi- ir para-pakeistų benzenkarboksirūgščių benzilidenhidrazidų, 2-pirimidinkarboksi- ir benzenkarboksirūgščių para-pakeistų benzilidenhidrazidų amidinės ir azometininės grupių protonų cheminiams poslinkiams. Nustatyta, kad amidinės ir azometininės grupių protonų cheminiai poslinkiai tiesiškai koreliuoja su pakaitų F, R konstantomis. Arilidenhidrazidų amidinis ir hidrazoninis fragmentai panašiai slopina pakaitų elektroninius efektusVilniaus universitetasVytauto Didžiojo universitetasŠvietimo akademij

Regarding the intramolecular cyclization of ethyl (E)- 2-cyano-3-(S-methylisothioureido)- 2-propenoate

It is known that, depending on the substituent in the ureido fragment, the intramolecular cyclization of esters of 2-cyano-3-(S-alkylisothioureido)-2-propenooic acid in basic catalysis conditions occurs by two routes to form a mixture of the corresponding 2-alkylsulfanyl-5-cyano-4(3H)-pyrimidinone salts and ethyl 2-alkylsulfanyl-4-amino-5-pyrimidine carboxylates [1-4]. At the same time, from our data, the cyclization reaction of 3-(S-alkyl- isothioureido)-2-cyano-2-propenoates in acid conditions has hardly been studiedChemijos institutasVilniaus pedagoginis universitetasVilniaus universitetasVytauto Didžiojo universitetasŠvietimo akademij

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di- tert -butyl-9-carbazolyl)-5-methylpyrimidines

The interest in organic materials exhibiting thermally activated delayed fluorescence (TADF) significantly increased in recent years owing to their potential application as emitters in highly efficient organic light emitting diodes (OLEDs). Simple modification of the molecular structure of TADF compounds through the selection of different electron-donating or accepting fragments opens great possibilities to tune the emission properties and rates. Here we present the synthesis of a series of novel pyrimidine–carbazole emitters and their photophysical characterization in view of effects of substituents in the pyrimidine ring on their TADF properties. We demonstrate that electron-withdrawing substituents directly connected to the pyrimidine unit have greater impact on the lowering of the energy gap between singlet and triplet states (Δ E ST ) for efficient TADF as compared to those attached through a phenylene bridge. A modification of the pyrimidine unit with CN, SCH 3 , and SO 2 CH 3 functional groups at position 2 is shown to enhance the emission yield up to 0.5 with pronounced TADF activity

Give or Take: Effects of Electron-Accepting/-Withdrawing Groups in Red-Fluorescent BODIPY Molecular Rotors

Mapping microviscosity, temperature, and polarity in biosystems is an important capability that can aid in disease detection. This can be achieved using fluorescent sensors based on a green-emitting BODIPY group. However, red fluorescent sensors are desired for convenient imaging of biological samples. It is known that phenyl substituents in the β position of the BODIPY core can shift the fluorescence spectra to longer wavelengths. In this research, we report how electron-withdrawing (EWG) and -donating (EDG) groups can change the spectral and sensory properties of β-phenyl-substituted BODIPYs. We present a trifluoromethyl-substituted (EWG) conjugate with moderate temperature sensing properties and a methoxy-substituted (EDG) molecule that could be used as a lifetime-based polarity probe. In this study, we utilise experimental results of steady-state and time-resolved fluorescence, as well as quantum chemical calculations using density functional theory (DFT). We also explain how the energy barrier height (Ea) for non-radiative relaxation affects the probe’s sensitivity to temperature and viscosity and provide appropriate Ea ranges for the best possible sensitivity to viscosity and temperature