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Synthesis of Monodisperse Naphthalene Dendrons for the Application of Dendrimers
Raveendra Jillella,김재웅,김건희,한진욱,오창호 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.9
Syntheses of dendrons for dendrimer applications are described using napthyl and urethane derivatives. The napthol, 1-(3-hydroxy-6-(methoxymethoxy)naphthalen-1-yl)ethan-1-one (h), was synthesized by employing Au-catalyzed cyclization of the corresponding propargylic carboxylates. Polynapthol dendrons (i, j, k, and l) were prepared from substitution reactions of napthyl derivative h with alkyl/aryl halides under basic conditions. Branched polyurethane compounds (q, r, and s) were also prepared from addition reactions of 1,3,5-tris(6-isocyanteohexyl)-1,3,5-triazine-2,4,6-trione (p) with various alcohols under Lewis acidic conditions. The photophysical properties of the synthesized compounds h, k, and j were studied.
Raveendra Pai,Kanchan Kohli,Gaurav Jain,Birendra Srivastava 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.7
In the present study, an extended release pellet dosage form of ketoprofen was prepared using powder layering technique. A combination of ethyl cellulose (45 cps) and shellac polymers was used as a binder (12% w/w polymer) during drug layering and an extended release coating (1:3 ratio at 2%, 4% and 7% w/w polymer) within the same apparatus. The coated pellets were characterized for sphericity, Hardness-Friability Index, and drug content, and also underwent scanning electron microscopy. In vitro dissolution was performed in 900 mL of phosphate buffer (pH 6.8) using paddle apparatus at 100 rpm. Ethyl cellulose and shellac when used as binders during drug loading did not extend ketoprofen release beyond 3 h. However, coating of the drug loaded pellets using ethyl cellulose and shellac resulted in an extended release profile of about 10 h. Using Higuchi’s model and the Korsmeyer equation, the drug release mechanism from the pellets was found to be an anomalous type involving diffusion and erosion. Scanning electron microscopy was used to visualize the pellet morphology and drug release mechanism during dissolution testing. In vivo evaluations of the extended release pellets in rats indicated a significant increase in the time to reach maximum concentration (t_max) and extent of absorption (AUC_(0-∞)) compared to the ketoprofen immediate release tablet blend dispersed and dosed. In conclusion, extended release pellets of ketoprofen could perform therapeutically better than conventional dosage forms, leading to improved efficacy for a prolonged period.
Jillella, Raveendra,Oh, Dong hwan,Oh, Chang Ho The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.20
<P>A simple, mild, efficient and chemoselective catalytic method for the straightforward synthesis of an interesting class of 2-aryl/alkyl-substituted-3-diaryl indolyl methanes in high yield is reported. This atom-efficient method proceeds <I>via</I> a gold-catalyzed one-pot sequential intramolecular hydroamination (C-N bond formation) of 2-alkynylanilines followed by a 1,6-conjugate addition to <I>p</I>-quinonemethides. The <I>p</I>-quinonemethides, which contain aldehyde functional groups, preferentially participate in 1,6-conjugate addition, while the aldehyde functional group remains unreactive.</P>
Ferromagnetic ReRAM in Sr(Fe,Co)O<SUB>x</SUB>
Venkata Raveendra Nallagatla,Harisankar S,Chang Uk Jung 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
Redox based Resistive random-access memory (RRAM) devices is considered as one of the most promising candidates for the next generation nonvolatile memory due to its excellent storage capacity, high scalability, robust retention, good endurance, and stability. Recent research shows that it has applicability in neuromorphic networks as an artificial synapsis is one of the major breakthroughs of the recent investigations. Recently, we introduced brownmillerite SrCoO2.5 and SrFeO2.5 as a novel material platform to harness exceptional oxygen ion transport properties for resistive switching memory devices for the first time. For SrFeO2.5, we were able to demonstrate an excellent resistive switching performance with high endurance (> 10<SUP>6</SUP> cycles), fast switching speed (10 ns) and high uniformity in key switching parameters. In this contest, compound with substitution of Co at the Fe lattice of SrFeO₃ is also found to be potential material for the resistive switching devices with excellent magneto-electrical coupling. SrFe1−xCoxO₃ (SFCO) gained attention recently due to its redox-driven topotactic transformation with a brownmillerite nonmagnetic phase to perovskite ferromagnetic phase . The solid-solution system SFCO exhibit antiferromagnetic-to-ferromagnetic transition as a function of Co concentration with a high Curie temperature of (TC= 300K). SrFe1−xCoxO₃ shows multiple magnetic phases varying from helimagnetic to cluster glass for lower Co concentrations (0≥ x ≤0.07), whereas the system switches to ferromagnetic state for higher (x> 0.2) values. In the present work we are interested to explore the electrical manipulation of magnetism and magnetic properties of PLD grown epitaxial SFCO thin films by varying the Co content as well as oxygen stoichiometry for the development of the high-quality magneto-electric switching devices. 〈그림 본문참조〉
이규환,Raveendra Jillella,김재웅,오창호 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.5
Propargylic pivaloates bearing an alkynyl group at a three?carbon tether under the gold catalysis would undergo [3,3] rearrangements of propargylic pivaloates followed by tandem [2+2] cyclization to give the corresponding 6?acylbicyclo[3,2,0]hept?6?ens. In continuing work, we prepared various substrates bearing two arms of alkyne?propargylic pivaloates to explore primitive dendrimer concept bicyclic compounds. Finally, we could obtain a series of diasteromeric compounds bearing two arms of 6?acylbicyclo[3,2,0]hept?6?ene groups in high yields.
Fabrication of Phosphorescence WOLED Based on Dimeric Phenoxazine Moiety for Hole Injection Layer
박민진,( Raveendra Jillella ),박종욱 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
Hole injection material, namely, 10,10_-bis(4-tert-butylphenyl)-N7, N7_-di(naphthalen-1-yl)-N7,N7_-diphenyl-10H,10_H-3,3_-biphenoxa zine-7,7_-diamine (1-PNA-BPBPOX), were adapted to white OLED devi ces for solution process. White devices were fabricated using a multilay er emission structure, consisting of a single host layer. The red phospho rescent, (Ir(piq)3_, and the blue phosphorescent,(FIrpic), are doped into separate layers of (mCP) host. The FIrpic and Ir(piq)3 guest molecules are directly excited by direct recombination on these molecules. When the device with BPBPOX was compared to the device with PEDOT:PSS, a commercialized solution HIL material, the luminance efficiency was 6.37 cd/A for BPBPOX and 0.66 cd/A for PEDOT:PSS for the optimized white device structure, showing 10 times as high efficiency.
민동주,Raveendra Jillella,박상신,강석우,박수영,박종욱 한국고분자학회 2021 Macromolecular Research Vol.29 No.12
A new electrical small molecule and polymers with electron-withdrawing effects stemming from a tetrazine moiety were synthesized. The electro-optical properties of 3-([1,1'-biphenyl]-3-yl)-6-(4-(tert-butyl)phenyl)-1,2,4,5-tetrazine (TBTTZ- DP), poly(9-ethyl-3-(4-(6-phenyl-1,2,4,5-tetrazin-3-yl)phenyl)-9H-carbazole) (ECBZ-TTZ), and poly(9-(henicosan-11-yl)-3-(3-(6-phenyl-1,2,4,5-tetrazin-3-yl)phenyl)- 9H-carbazole) (DCBZ-TTZ) were compared. TB-TTZ-DP, ECBZ-TTZ, and DCBZTTZ in the solution state exhibited maximum absorption wavelengths of 309, 312, and 321 nm, respectively; in the film state, they exhibited maximum absorption wavelengths of 308, 341, and 302 nm, respectively. These results correspond to bandgaps of 3.63, 3.10, and 3.54 eV, respectively. The ECBZ-TTZ and DCBZ-TTZ polymers exhibited maximum PL wavelengths of not only 411, 474, and 407 nm in the solution state but also 412 and 476 nm (ECBZ-TTZ) and 371 and 416 nm (DCBZ-TTZ) in the film state. The electrochemical properties of the three materials were tested in the potential range from -0.5 to 1.5 V and all three materials demonstrated stable redox properties. The exponent of the scan rate (i.e., the x-value) for TB-TTZ-DP, ECBZ-TTZ, and DCBZ-TTZ was 0.61, 0.64, and 0.77, respectively. The kinetics of the redox process were controlled by combination of diffusion and electron transfer processes. Among organic lightemitting diodes fabricated using the three materials, the device with DCBZ-TTZ exhibited the best current–voltage characteristics.