The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Jun Yeob Lee - One of the best experts on this subject based on the ideXlab platform.
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high quantum efficiency and color stability in white phosphorescent organic light emitting diodes using Carboline Derivative as a host material
Organic Electronics, 2013Co-Authors: Bo Seong Kim, Jun Yeob LeeAbstract:Abstract Highly efficient and color stable phosphorescent white organic light-emitting diodes were developed using a high triplet energy host material, 3,3′-bis(9H-pyrido[2,3-b]indol-9-yl)-1,1′-biphenyl (CbBPCb), derived from Carboline. Two color phosphorescent white organic light-emitting diodes were fabricated by co-doping of blue and orange triplet emitters or double emitting layer structure of blue and orange emitting layers. High quantum efficiency above 20% and color stability were achieved in the white device by optimizing the doping concentration and emitting layer thickness.
Leonardo Silva Santos - One of the best experts on this subject based on the ideXlab platform.
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Sintese da homopumiliotoxina 223G, arborescidinas A-C, levobupivacaina e mepivacaiana : estrategia de sintese da pleiocarpamina e akagerina : estudo mecanistico de rações utilizando ESI-MS/MS
2017Co-Authors: Leonardo Silva SantosAbstract:Resumo: O presente trabalho iniciou-se com a síntese da Homopumiliotoxina, onde a combinação de reação de amidoalquilação estereosseletiva, condensação aldólica e eliminação estereoespecífica permitiu a construção da unidade olefinica trisubstituída presente no núcleo quinolizidínico encontrado neste aIcalóide. A síntese estereosseletiva da (±)-Homopumiliotoxina 223G (28) foi alcançada em 6 etapas e rendimento total superior a 20% a partir do precursor do íon N-acilimínio 2-metoxi-(N-1-carbobenziloxi) piperidina (3a). Ainda, dois anestésicos ((S)-levobupivacaína e (S)-mepivacaína) foram sintetizados em 76% de ee e rendimentos superiores a 71% empregando-se a química de N-acilimínio quirais. Concomitantemente, as primeiras sínteses enantiosseletivas da (+)-Arborescidina A (33) (5 etapas, 50% rendimento total), (-)-Arborescidina B (34) (8 etapas, 61% de rendimento total) e (-)-Arborescidina C (35) (9 etapas, 51% de rendimento total) foram alcançadas em altos excessos enantioméricos (92-96% ee). Tentativa de síntese de um outro aIcalóide, a (R)-Akagerina, foi iniciada introduzindo-se a assimetria na molécula através da hidrogenação assimétrica de Noyori a partir de um derivado b-carbolínico (93% ee). Uma nova metodologia para a redução assimétrica de iminas utilizando complexos supramoleculares calix[6]areno/(R)-PEA foi descrita, baseando-se em complexos supramoleculares formados a partir de calix[6]areno/amina quiral, mimetizando enzimas e NaBH4 com o papel de agente redutor. Uma outra estratégia elegante foi utilizada para a obtenção da Pleiocarpamina, um alcalóide pentacíclico pertencente ao grupo dos alcalóides indólicos Corinanteanos, testando-se a viabilidade da utilização da reação de Heck para a formação do sistema pentacíclico encontrado no aIcalóide. Finalmente, estudo mecanístico da reação de olefinação de Petasis foi realizado empregando-se APCI-MS/MS.Abstract: A novel approach to the total synthesis of (±)-Homopumiliotoxin 223G was achieved in six steps and 20% yield through the addition of 5-methyl-2-triisopropylsilyoxyfuran (4b) to the N-acyliminium ion derived from N-Cbz-2- methoxypiperidine (3a) featuring bicyclic lactam 13 as the key intermediate. This work offers new general routes to a series of Homopumiliotoxin alkaloids other than the alkaloids described here that are currently being investigated in this laboratory. Two anesthesics [(S)-levobupivacaine and (S)-mepivacaine] were synthesized in 76% ee and yields higher than 71% through the chiral N-acyliminium chemistry. The first and efficient synthesis of (R)-(+)-Arborescidine A (33) (5 steps, 50% overall yeild), (-)-Arborescidine B (34) (8 steps, 61% overall yield) and (-)-Arborescidine C (35) (9 steps, 51% overall yield) were achieved in high enantiomeric excesses (92-96% ee), using the Noyori asymmetric hydrogenation of imines. This work herein confirmed the previously assigned S configuration of natural Arborescidines. A strategy of synthesis of (R)-Akagerine was studied achieving the chiral tricyclic compound 72 in 93% ee through the Noyori asymmetric hydrogenation of a b-Carboline Derivative 71. A novel approach to the asymmetric reduction of dihydro-b-Carboline Derivatives to the corresponding tetrahydro-b-Carboline is described based on the supramolecular complex formed from calix[6]arene/chiral amine as an enzyme mimetic and NaBH4 as the reducing agent. A new strategy to the Pleiocarpamine alkaloid was studied, testing the feasibility of the Heck reaction in the construction of pentacyclic system found in this class of compounds. Additionally, mechanistic study of Petasis olefination was performed employing APCI-MS/MS
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Sintese da homopumiliotoxina 223G, arborescidinas A-C, levobupivacaina e mepivacaiana : estrategia de sintese da pleiocarpamina e akagerina : estudo mecanistico de rações utilizando ESI-MS/MS
Universidade Estadual de Campinas. Instituto de Quimica, 2003Co-Authors: Leonardo Silva SantosAbstract:O presente trabalho iniciou-se com a síntese da Homopumiliotoxina, onde a combinação de reação de amidoalquilação estereosseletiva, condensação aldólica e eliminação estereoespecífica permitiu a construção da unidade olefinica trisubstituída presente no núcleo quinolizidínico encontrado neste aIcalóide. A síntese estereosseletiva da (±)-Homopumiliotoxina 223G (28) foi alcançada em 6 etapas e rendimento total superior a 20% a partir do precursor do íon N-acilimínio 2-metoxi-(N-1-carbobenziloxi) piperidina (3a). Ainda, dois anestésicos ((S)-levobupivacaína e (S)-mepivacaína) foram sintetizados em 76% de ee e rendimentos superiores a 71% empregando-se a química de N-acilimínio quirais. Concomitantemente, as primeiras sínteses enantiosseletivas da (+)-Arborescidina A (33) (5 etapas, 50% rendimento total), (-)-Arborescidina B (34) (8 etapas, 61% de rendimento total) e (-)-Arborescidina C (35) (9 etapas, 51% de rendimento total) foram alcançadas em altos excessos enantioméricos (92-96% ee). Tentativa de síntese de um outro aIcalóide, a (R)-Akagerina, foi iniciada introduzindo-se a assimetria na molécula através da hidrogenação assimétrica de Noyori a partir de um derivado b-carbolínico (93% ee). Uma nova metodologia para a redução assimétrica de iminas utilizando complexos supramoleculares calix[6]areno/(R)-PEA foi descrita, baseando-se em complexos supramoleculares formados a partir de calix[6]areno/amina quiral, mimetizando enzimas e NaBH4 com o papel de agente redutor. Uma outra estratégia elegante foi utilizada para a obtenção da Pleiocarpamina, um alcalóide pentacíclico pertencente ao grupo dos alcalóides indólicos Corinanteanos, testando-se a viabilidade da utilização da reação de Heck para a formação do sistema pentacíclico encontrado no aIcalóide. Finalmente, estudo mecanístico da reação de olefinação de Petasis foi realizado empregando-se APCI-MS/MS.A novel approach to the total synthesis of (±)-Homopumiliotoxin 223G was achieved in six steps and 20% yield through the addition of 5-methyl-2-triisopropylsilyoxyfuran (4b) to the N-acyliminium ion derived from N-Cbz-2- methoxypiperidine (3a) featuring bicyclic lactam 13 as the key intermediate. This work offers new general routes to a series of Homopumiliotoxin alkaloids other than the alkaloids described here that are currently being investigated in this laboratory. Two anesthesics [(S)-levobupivacaine and (S)-mepivacaine] were synthesized in 76% ee and yields higher than 71% through the chiral N-acyliminium chemistry. The first and efficient synthesis of (R)-(+)-Arborescidine A (33) (5 steps, 50% overall yeild), (-)-Arborescidine B (34) (8 steps, 61% overall yield) and (-)-Arborescidine C (35) (9 steps, 51% overall yield) were achieved in high enantiomeric excesses (92-96% ee), using the Noyori asymmetric hydrogenation of imines. This work herein confirmed the previously assigned S configuration of natural Arborescidines. A strategy of synthesis of (R)-Akagerine was studied achieving the chiral tricyclic compound 72 in 93% ee through the Noyori asymmetric hydrogenation of a b-Carboline Derivative 71. A novel approach to the asymmetric reduction of dihydro-b-Carboline Derivatives to the corresponding tetrahydro-b-Carboline is described based on the supramolecular complex formed from calix[6]arene/chiral amine as an enzyme mimetic and NaBH4 as the reducing agent. A new strategy to the Pleiocarpamine alkaloid was studied, testing the feasibility of the Heck reaction in the construction of pentacyclic system found in this class of compounds. Additionally, mechanistic study of Petasis olefination was performed employing APCI-MS/MS
Liangsheng Liao - One of the best experts on this subject based on the ideXlab platform.
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a facile way to synthesize high triplet energy hosts for blue phosphorescent organic light emitting diodes with high glass transition temperature and low driving voltage
Dyes and Pigments, 2015Co-Authors: Yakun Wang, Yali Deng, Xiaodong Yuan, Zuoquan Jiang, Liangsheng LiaoAbstract:Abstract Two novel bipolar host materials were designed and synthesized, by incorporating α-Carboline and carbazole to spiro-acridine-fluorene skeleton. As expected, both materials exhibited high triplet energy over 2.8 eV, indicating they could act as suitable blue hosts in phosphorescent organic light-emitting diodes. By changing the appending group from carbazole to α-Carboline, the thermal property and molecular bipolarity were improved. When they were applied as hosts for sky-blue emitter iridium(III) bis[4,6-difluorophenyl]pyridinato-N, C2′ ] picolinate (FIrpic), good performance of 35.5 cd A−1, 35.8 lm W−1 and 29.5 cd A−1, 24.5 lm W−1 was achieved for α-Carboline Derivative and carbazole Derivative, respectively.
Yirang Im - One of the best experts on this subject based on the ideXlab platform.
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thermally stable Carboline Derivative as a host material for blue phosphorescent organic light emitting diodes
Organic Electronics, 2013Co-Authors: Yirang ImAbstract:Abstract A α-Carboline based high triplet energy material, 9,9′-(5′-(carbazol-9-yl)-[1,1′:3′,1″-terphenyl]-3,3″-diyl)di-α-Carboline (2CbCzT), was designed and synthesized as the thermally stable host material for blue phosphorescent organic light-emitting diodes (PHOLEDs). The 2CbCzT host showed high glass transition temperature of 149 °C and high decomposition temperature of 518 °C at 5% weight loss. In addition, the 2CbCzT exhibited bipolar charge transport properties due to hole transport type carbazole and electron transport type α-Carboline units. Blue PHOLEDs were developed using the high triplet energy 2CbCzT host material and a high quantum efficiency of 22.1% was obtained.
G Biggio - One of the best experts on this subject based on the ideXlab platform.
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the effects of inhibitors of gabaergic transmission and stress on brain and plasma allopregnanolone concentrations
British Journal of Pharmacology, 1997Co-Authors: Maria Luisa Barbaccia, Gianna Roscetti, Marco Trabucchi, Robert H Purdy, Mc Mostallino, A Concas, G BiggioAbstract:1. This study was undertaken to investigate the relationship between a reduction in brain GABAA receptor function and the cerebro-cortical content of 3 alpha-hydroxy-5 alpha-pregnan-20 one (allopregnanolone, AP), a potent endogenous positive modulator of 7-aminobutyric acid (GABA) action at GABAA receptors, with anticonflict and anticonvulsant effects in rodents. 2. An acute depletion of the cerebral content of GABA or an attenuation of GABAA receptor-mediated transmission by systemic injections of isoniazid (375 mg kg-1, s.c.) or FG 7142 (15 mg kg-1, i.p.) induced a transient increase in the cerebro-cortical and plasma concentrations of AP in handling-habituated (not stressed) rats. 3. Two stress paradigms, handling in naive rats and mild foot shock in handling-habituated rats, that reduce central GABAergic tone mimicked the effects of isoniazid and FG 7142 on cortical AP content; foot shock in handling-habituated rats, but not handling in naive animals, also increased plasma AP. Isoniazid, FG 7142, and foot shock also each increased the concentrations of the AP precursors, pregnenolone and progesterone, in both brain and plasma of handling-habituated rats, whereas handling in naive rats increased the concentrations of these steroids only in brain. 4. Pretreatment of handling-habituated rats with the anxiolytic beta-Carboline Derivative abecarnil, a positive allosteric modulator of GABAA receptors, which per se failed to affect the AP concentration in brain or plasma, prevented the increase in brain and plasma AP induced by foot shock or isoniazid. 5. In adrenalectomized and castrated rats foot shock or isoniazid failed to increase AP both in brain cortex and plasma. 6. These observations indicate that inhibition of GABAergic transmission, induced by foot shock or pharmacological manipulations, results in an increase in the concentrations of AP in brain and plasma, possibly via a modulation of hypothalamic-pituitary-adrenal (HPA) axis. 7. Given that AP enhances GABAA receptor function with high efficacy and potency, an increase in brain AP concentration may be important in the fine tuning of the GABA-mediated inhibitory transmission in the central nervous system.
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failure of flumazenil to precipitate a withdrawal syndrome in cats chronically treated with the new anxioselective beta Carboline Derivative abecarnil
Behavioural Pharmacology, 1993Co-Authors: Mariangela Serra, Cristina A Ghiani, M C Foddi, R Galici, Costantino Motzo, G BiggioAbstract:The effect of chronic administration of the novel anxiolytic beta-Carboline Derivative, abecarnil (isopropyl-6-benzyloxy-4-methoxymethyl-beta-Carboline-3-carboxylate), was examined and compared with the capability of diazepam to induce physical dependence in cats. The acute administration of the benzodiazepine receptor antagonist, flumazenil (20mg/kg i.p.), to cats treated for 2 weeks with diazepam (7mg/kg i.p., three times daily), induced a severe withdrawal syndrome characterized by the appearance of severe physical signs. Within minutes all cats displayed tremors, increased muscle tone, fear response, repeated vocalization and salivation. On the contrary, in all cats treated chronically (2 weeks) with abecarnil (7mg/kg i.p. three times daily) the challenge dose of flumazenil failed to precipitate a clear abstinence syndrome. In fact, a pupillary dilatation and a mild fear response were the only signs present 15-30min after flumazenil administration. This finding indicates that abecarnil, a new potential therapeutic agent for anxiety disorders and seizures, might have advantages over classical benzodiazepines with regard to development of physical dependence.
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pharmacology of gamma aminobutyric acida receptor complex after the in vivo administration of the anxioselective and anticonvulsant beta Carboline Derivative abecarnil
Journal of Pharmacology and Experimental Therapeutics, 1992Co-Authors: Mariangela Serra, Cristina A Ghiani, M C Foddi, Costantino Motzo, M A Melis, Alessandra Concas, Enrico Sanna, G BiggioAbstract:In rodents, the effect of the beta-Carboline Derivative isopropyl-6- benzyloxy-4-methoxymethyl-beta-Carboline-3-carboxylate (abecarrnil), a new ligand for benzodiazepine receptors possessing anxiolytic and anticonvulsant properties, was evaluated on the function of central gamma-aminobutyric acid (GABA)A receptor complex, both in vitro and in vivo. Added in vitro to rat cortical membrane preparation, abecarnil increased [3H]GABA binding, enhanced muscimol-stimulated 36Cl- uptake and reduced the binding of t-[35S]butylbicyclophosphorothionate ([35S]TBPS). These effects were similar to those induced by diazepam, whereas the partial agonist Ro 16-6028 (tert-butyl-(S)-8-bromo-11,12,13,13a-tetrahydro-9-oxo-9H- imidazo[1,5-a]-pyrrolo-[2,1-c][1,4]benzodiazepine-1-carboxylate) showed very weak efficacy in these biochemical tests. After i.p. injection to rats, abecarnil and diazepam decreased in a time-dependent and dose-related (0.25-20 mg/kg i.p.) manner [35S]TBPS binding measured ex vivo in the cerebral cortex. Moreover, both drugs at the dose of 0.5 mg/kg antagonized completely the convulsant activity and the increase of [35S]TBPS binding induced by isoniazide (350 mg/kg s.c.) as well as the increase of [35S]TBPS binding induced by foot-shock stress. To better correlate the biochemical and the pharmacological effects, we studied the action of abecarnil on [35S]TBPS binding, exploratory motility and on isoniazid-induced biochemical and pharmacological effects in mice. In these animals, abecarnil produced a paralleled dose-dependent (0.05-1 mg/kg i.p.) reduction of both motor behavior and cortical [35S]TBPS binding. Moreover, 0.05 mg/kg of this beta-Carboline reduced markedly the increase of [35S]TBPS binding and the convulsions induced by isoniazid (200 mg/kg s.c.).(ABSTRACT TRUNCATED AT 250 WORDS)