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721.
Pratap Kumar Saha Buddhadeb Dutta Sreyashi Jana Rajesh Bera Sandip Saha Ken-ichi Okamoto Subratanath Koner 《Polyhedron》2007
A new zeolite-immobilized hybrid catalyst Cu(MeO-salen)-NaY has been prepared by encapsulating [Cu(MeO-salen)(H2O)] (1) [where MeO-salenH2 = N,N′-(ethylene)-bis-(3-methoxysalicylaldimine)] in a NaY zeolite matrix. The hybrid material has been characterized by UV–Vis, IR and EPR spectrometry and by X-ray powder diffraction analysis. The pristine complex [Cu(MeO-salen)(H2O)] (1) has also been synthesized and characterized by all the spectrometric methods mentioned above as well as by single crystal X-ray diffraction analysis. A brilliant color change (green to red) has been observed when the complex [Cu(MeO-salen)(H2O)] (1) is immobilized in the zeolitic matrix. X-ray powder diffraction analysis of Cu(MeO-salen)-NaY reveals that the structural integrity of the mother zeolite in the hybrid material remains intact upon immobilization of the complex. The coordination geometry around the CuII ion in [Cu(MeO-salen)(H2O)] is found to be square pyramidal. Spectroscopic studies indicate that coordination geometry of the complex undergoes a significant distortion when it is entrapped in the zeolite cavity. While Cu(MeO-salen)-NaY shows excellent catalytic activity and product selectivity in the hydroxylation of phenol and 1-naphthol, [Cu(MeO-salen)(H2O)] (1) remains virtually catalytically inactive in these reactions. 相似文献
722.
As a new class of inorganic phosphor, orthophosphate phosphors materials have received great interest because of their potential applications in solid-state lightings and displays. In this article, we focus on current developments in the synthesis, crystal structure and luminescence properties of orthophosphate phosphors for solid-state lightings. We discuss the synthesis of a family of orthophosphate phosphor doped with europium (Eu2+ and Eu3+) by traditional and novel methods. In the fluorescent lamp, phosphor materials convert UV radiation into visible radiation. Lamp phosphors are mostly white in color and they should not absorb the visible radiation. New phosphors that can absorb excitation energy from blue or near ultraviolet (n-UV) LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450–480 nm) and n-UV (380–400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Here, we will review the status of phosphors for solid-state lightings and prospect the future development. The impacts of doping of europium and photoluminescence properties on orthophosphate phosphors were investigated and we propose a feasible interpretation. 相似文献
723.
T. RameshR.S. Shinde S.R. Murthy 《Journal of magnetism and magnetic materials》2011,323(12):1593-1598
Modern accelerator design practice includes the use of high-quality ferrites for circulator applications with ever-increasing requirements on power handling ability. Modeling studies of new designs are of increasing economic importance, but are frequently hindered by lack of measured values of the ceramic loss factors. We have developed a nanocrystalline ferrite material with composition Ni0.94Co0.03Mn0.04Cu0.03Fe1.96O4. Nanocrystalline NiCoMnCu ferrite powders were synthesized using a microwave-hydrothermal method at 160 °C for 40 min. The ferrite formation conditions, such as pH, temperature and time, were optimized. The phase of the samples was identified by X-ray diffraction and was characterized by Fourier transformation infrared spectroscopy. The size of the nanocrystalline ferrite of as-synthesized powders was 10 nm. The powder was densified at different temperatures using a microwave sintering method. The complex permittivity and permeability of the sintered samples were measured over a frequency range from 10 kHz to 1.8 GHz at room temperature. The applicability of the samples for circulators was tested via the measurement of the ferromagnetic resonance linewidth and the results are presented. 相似文献
724.
Jadhav SV Bandyopadhyay A Benke SN Mali SM Gopi HN 《Organic & biomolecular chemistry》2011,9(11):4182-4187
A facile, efficient and racemization-free method for the synthesis of N-protected β-amino alcohols and peptaibols using N-hydroxysuccinimide active esters is described. Using this method, dipeptide, tripeptide and pentapeptide alcohols were isolated in high yields. The conformations in crystals of β-amino alcohol, dipeptide and tripeptide alcohols were analysed, with a well-defined type III β-turn being observed in the tripeptide alcohol crystals. This method is found to be compatible with Fmoc-, Boc- and other side-chain protecting groups. 相似文献
725.
726.
Baljinder Singh Rajinder Parshad R.K. Khajuria Santosh K. Guru Anup S. Pathania Rashmi Sharma Reena Chib Subrayashastry Aravinda Vivek K. Gupta Inshad A. Khan Shashi Bhushan Sandip B. Bharate Ram A. Vishwakarma 《Tetrahedron letters》2013
From an antimicrobial gram-positive actinomycete strain of Saccharomonospora azurea (MTCC11714) isolated from high altitude soil of Kargil (J&K, India), a new isocoumarin saccharonol B (2) along with two known compounds viz. saccharonol A (1) and piericidin A3 (3) was isolated and characterized. The structure of the new compound was established based on extensive 2D-NMR data. Saccharonol B (2) exhibited mild antimicrobial activity against a standard panel of microorganisms Staphylococcus aureus ATCC 29213, Candida albicans ATCC 90028, and Aspergillus fumigatus MTCC 1811 with MIC values in the range of 128–248 μg/mL. Saccharonol B (2) and piericidin A3 (3) showed selective cytotoxic activity against human pancreatic carcinoma cell line (MIAPaCa-2) with IC50 values of 9 and 8 μM, respectively. Mechanistic studies indicated that saccharonol B (2) arrests S-phase of the cell cycle and causes dose-dependent loss of mitochondrial potential in MIAPaCa-2 cells. 相似文献
727.
Sandip V. Jadhav Rajkumar Misra Sumeet K. Singh Dr. Hosahudya N. Gopi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16256-16262
Hybrid peptides composed of α‐ and β‐amino acids have recently emerged as new class of peptide foldamers. Comparatively, γ‐ and hybrid γ‐peptides composed of γ4‐amino acids are less studied than their β‐counterparts. However, recent investigations reveal that γ4‐amino acids have a higher propensity to fold into ordered helical structures. As amino acid side‐chain functional groups play a crucial role in the biological context, the objective of this study was to investigate efficient synthesis of γ4‐residues with functional proteinogenic side‐chains and their structural analysis in hybrid‐peptide sequences. Here, the efficient and enantiopure synthesis of various N‐ and C‐terminal free‐γ4‐residues, starting from the benzyl esters (COOBzl) of N‐Cbz‐protected (E)‐α,β‐unsaturated γ‐amino acids through multiple hydrogenolysis and double‐bond reduction in a single‐pot catalytic hydrogenation is reported. The crystal conformations of eight unprotected γ4‐amino acids (γ4‐Val, γ4‐Leu, γ4‐Ile, γ4‐Thr(OtBu), γ4‐Tyr, γ4‐Asp(OtBu), γ4‐Glu(OtBu), and γ‐Aib) reveals that these amino acids adopted a helix favoring gauche conformations along the central Cγ? Cβ bond. To study the behavior of γ4‐residues with functional side chains in peptide sequences, two short hybrid γ‐peptides P1 (Ac‐Aib‐γ4‐Asn‐Aib‐γ4‐Leu‐Aib‐γ4‐Leu‐CONH2) and P2 (Ac‐Aib‐γ4‐Ser‐Aib‐γ4‐Val‐Aib‐γ4‐Val‐CONH2) were designed, synthesized on solid phase, and their 12‐helical conformation in single crystals were studied. Remarkably, the γ4‐Asn residue in P1 facilitates the tetrameric helical aggregations through interhelical H bonding between the side‐chain amide groups. Furthermore, the hydroxyl side‐chain of γ4‐Ser in P2 is involved in the interhelical H bonding with the backbone amide group. In addition, the analysis of 87 γ4‐residues in peptide single‐crystals reveal that the γ4‐residues in 12‐helices are more ordered as compared with the 10/12‐ and 12/14‐helices. 相似文献
728.
Ramakrishna V. S. Nirogi Rama Sastri Kambhampati Prabhakar Kothmirkar Sobhanadri Arepalli Narasimha Reddy G. Pamuleti Anil K. Shinde 《合成通讯》2013,43(19):2835-2851
Abstract Several functionalized thienopyrimidines were synthesized by a facile synthetic method, which includes Gewald's reaction, and were characterized by spectral and analytical data. These functionalized thienopyrimidines were converted to various new chemical entities of biological importance, such as 2-piperazinymethyl thienopyrimidines (6, 8), 4-dimethylaminoethoxy thienopyrimidines (11), and 3-dimethylaminoethyl thienopyrimidines (12). All the compounds thus synthesized were screened for their invitro biological activities. Some of the compounds displayed promising serotonin 5-HT6 receptor antagonist activities.
ACKNOWLEDGMENT
The support received from the Discovery Analytical Department and Venkateswarlu Jasti, CEO, Suven Life Sciences Ltd., Hyderabad, is gratefully acknowledged. 相似文献729.
Subbarao Jammula Venkateswara Rao Anna Sandip R. Khobare U. K. Syam Kumar Bagineni Prasad 《合成通讯》2013,43(22):2576-2582
A dehydrative annulation strategy involving an intramolecular ring closure under a Mitsunobu-type reaction condition has been used for the construction of octahydroindolizine framework successfully. This strategy that was reported to be unsuccessful when applied to a similar system allowed us to perform a diastereoselective synthesis of (6R,8aS)-octahydroindolizin-6-ol [a precursor of (–)-8a-epidesacetoxyslaframine] starting from commercially available chiral (S)-epichlorohydrin via a piperidine intermediate, i.e., (3R,6S)-6-(3-hydroxypropyl)piperidin-3-ol. The methodology has potential to afford a library of optically pure small molecules of pharmacological importance based on the related indolizine framework. 相似文献
730.
Shahul Hameed P. Gajanan Shanbhag Vikas Shinde Murugan Chinnapattu Praveena Manjrekar Jayashree Puttur 《合成通讯》2013,43(24):3315-3321
Short and efficient route for the synthesis of oxazinone- and thiazinone-containing bicyclic heteroaromatic aldehydes, which involves the key step of palladium-catalyzed reductive carbonylation, is described. Overall routes for the synthesis of these aldehydes are short, versatile, and scalable with good yields of the product. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献