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151.
Manoj Kr. Paul Rahul K. Nath Brian Moths LiDong Pan Shun Wang Rajdeep Deb 《Phase Transitions》2013,86(12):1070-1078
Depolarized reflected light microscopy and high resolution optical reflectivity measurements have been conducted on free-standing films of an achiral four-ring hockey stick shaped liquid crystal exhibiting SmA-B2–SmX* transition sequence. A layer thinning transition above the bulk isotropic-SmA phase transition has been observed. This behaviour was highly irreproducible, indicating an irregular layer thinning transition. From optical reflectivity data, both thickness of the free-standing films and the smectic interlayer spacing were determined. This is the first report of the layer thinning transition in a hockey stick shaped liquid crystal. 相似文献
152.
153.
Vikash Kumar Viraj G. Naik Avijit Das Sourayan Basu Bal Malabika Biswas Nupur Kumar Anasuya Ganguly Amrita Chatterjee Mainak Banerjee 《Tetrahedron》2019,75(27):3722-3732
Available online Development of water soluble AIE-active “light-up” bioprobes for the detection of biomacromolecules has drawn huge research interests in recent past. In this study, a series of ethylene glycol modified water soluble tetrameric tetraphenylethylene amphiphiles with pyridinium polar heads (TPE-xEG-Py, x = 3, 4, 6 or 1a-c) have been synthesized by varying the ethylene glycol spacer. Their unique structure allows them to form vesicles and other nanoaggregates in aqueous solutions. These amphiphiles were successfully utilized for fluorimetric detection and quantitation of BSA and DNA based on the electrostatic interactions to trigger AIE-emission from the TPE moiety. The electrostatic interaction was also proved very effective in wash-free imaging of both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria with up to 92 folds increase in fluorescence response within bacterial concentration 0–12 × 108 CFU mL?1. The strategy is advantageous due to cost-effective and easy synthesis, high water solubility, and fast response. 相似文献
154.
Kazuto Takaishi Bikash Dev Nath Yuya Yamada Hiroyasu Kosugi Tadashi Ema 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):10089-10093
Unique self‐assembled macrocyclic multinuclear ZnII and NiII complexes with binaphthyl‐bipyridyl ligands (L) were synthesized. X‐ray analysis revealed that these complexes consisted of an outer ring (Zn3L3 or Ni3L3) and an inner core (Zn2 or Ni). In the ZnII complex, the inner Zn2 part rotated rapidly inside the outer ring in solution on an NMR timescale. These complexes exhibited dual catalytic activities for CO2 fixations: synthesis of cyclic carbonates from epoxides and CO2 and temperature‐switched N‐formylation/N‐methylation of amines with CO2 and hydrosilane. 相似文献
155.
Ramendra Nath Majumdar 《Pramana》2008,70(5):949-953
The fragmentation of deuteron, 6He and 11Be have been studied during interaction with the 208Pb nucleus at various projectile energies. The Coulomb dissociation cross-sections and the momentum distribution of the break-up
fragments have been analysed within the framework of the direct fragmentation model. The post-acceleration effect of deuteron
during break-up and the halo structures of both the 6He and 11Be have been investigated.
相似文献
156.
P.D. Shidling N. Madhavan V.S. Ramamurthy S. Nath N.M. Badiger Santanu Pal A.K. Sinha A. Jhingan S. Muralithar P. Sugathan S. Kailas B.R. Behera R. Singh K.M. Varier M.C. Radhakrishna 《Physics letters. [Part B]》2008
Evaporation residue (ER) cross sections and gamma multiplicity distributions have been measured for 16O + 184W and 19F + 181Ta systems in the excitation energy range of 50–90 MeV, leading to the same compound nucleus 200Pb∗. Comparison of experimental results of both the systems shows that ER cross sections and moments of gamma multiplicity distribution of 16O + 184W system are significantly higher than those of 19F + 181Ta system at higher excitation energies. Present measurements directly shows the experimental signature of entrance channel effect even with the systems which are not very different with respect to their entrance channel mass asymmetry. It is further demonstrated that the reduction in the ER cross section and moments of spin distribution for 19F + 181Ta system is mainly due to the suppression of fusion of higher l values. 相似文献
157.
Angshuman Ghosh Soumen Kumar Dubey Dr. Maxcimilan Patra Jishu Mandal Narendra Nath Ghosh Priyanka Das Arpita Bhowmick Dr. Keka Sarkar Dr. Suprabhat Mukherjee Rajat Saha Dr. Subham Bhattacharjee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202201621
We have shown solvent- and substrate-dependent chiral inversion of a few glycoconjugate supramolecules. (Z)-F-Gluco, in which d -glucosamine has been attached chemically to Cbz-protected l -phenylalanine at the C terminus, forms a self-healing hydrogel through intertwining of the nanofibers wherein the gelators undergo lamellar packing in the β-sheet secondary structures with a single chiral handedness. Dihybrid (Z)-F-gluco nanocomposite gel was prepared by in-situ formation of silver nanoparticles AgNPs in the gel; this enhances the mechanical properties of the composite gel through physical crosslinking without altering the packing pattern. In contrast, (Z)-L-gluco bearing an l -leucine moiety does not form a hydrogel but an organogel. Interestingly, the chiral handedness of the aggregates of (Z)-L-gluco can be reversed by choosing suitable solvents. In addition to self-healing behavior, (Z)-L-gluco gel revealed shape persistency. Further, (Z)-F-gluco hydrogel is benign, nontoxic, non-immunogenic, and non-allergenic in animal cells. AgNP-loaded (Z)-F-gluco hydrogel showed antibacterial activity against both Gram-positive and Gram-negative bacteria. 相似文献
158.
Shyam Sundar Mondal Namita Jaiswal Partha Sarathi Bera Ranjay K. Tiwari Jogendra Nath Behera Nripen Chanda Subhas Ghosal Tanmoy Kumar Saha 《应用有机金属化学》2021,35(1)
A series of copper (II) ( 1 and 3 ) and cobalt (II/III) ( 2 , 4 and 5 ) complexes comprising different imino‐phenolate ligands DCH , DTH and DBH 2 (where DCH = 2,4‐dichloro‐6‐((mesitylimino)methyl)phenol, DTH = 2,4‐di‐tert‐butyl‐6‐((mesitylimino)methyl) phenol and DBH 2 = 2,4‐dibromo‐6‐((mesitylimino)methyl)phenol) have been prepared with excellent yield and high purity. By utilizing different spectroscopic tools such as UV–visible, electrospray ionization (ESI)‐mass, Fourier‐transform infrared (FTIR) spectrometry and elemental analysis, the prepared complexes ( 1 – 5 ) were thoroughly characterized. The molecular structure of the synthesized complexes was ascertained by using single‐crystal X‐ray diffraction studies (SCXRDs). The experiment reveals that Complexes 1 – 5 bind to calf thymus DNA (CT‐DNA) through non‐intercalative way with good interacting abilities. However, 1 – 5 are excellent quenchers of the fluorescence intensity of bovine serum albumin (BSA) following the static pathway. Additionally, they had shown remarkable cytotoxic potential against MCF‐7 (mammary gland adenocarcinoma) and A549 (lung adenocarcinoma) cell lines. The IC50 values associated with these complexes were much lower than the conventional drug cisplatin. Apoptosis‐induced cell death was confirmed from the DNA fragmentation studies and Hoechst 33342 staining. The 2′,7′‐dichlorofluorescein diacetate (DCFDA) assay indicates that the complex mediated reactive oxygen species (ROS) generation is accountable for governing the apoptosis mechanism via oxidative cell distress. Apart from these studies, by carrying out density functional theory (DFT) method, highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap calculations and optimized structures of the synthesized complexes were accomplished. 相似文献
159.
This study encompasses the synthesis and characterization of organotin(IV) derivatives of non-steroidal anti-inflammatory drug ibuprofen (IBF), viz. [(Me3Sn)(IBF)] ( 1 ), [(Bu3Sn)(IBF)] ( 2 ), [Ph3Sn(IBF)] ( 3 ), {[Me2Sn(IBF)]2O}2 ( 4 ) and [Bu2Sn(IBF)2] ( 5 ). The crystal structure of complex 3 , [Ph3Sn(IBF)], indicates a highly distorted tetrahedral (td) geometry with anisobidentate mode of coordination of the carboxylate group with tin atom, and a similar structure has been proposed for other two triorganotin(IV) derivatives. Moreover, the DFT (density functional theory) calculation and other studies have verified a dimer distannoxane type of structure for complex 4 , {[Me2Sn(IBF)]2O}2. Complex 5 has been found to exhibit a highly distorted octahedral geometry around the tin atom. To investigate the DNA binding profile of the synthesized complexes, viscosity measurement, UV–vis and fluorescence titrations were performed, which revealed an intercalative type of binding with DNA for IBF and complex 5 and external binding in case of the complexes 1 and 2 ; complexes 3 and 4 could not be studied owing to their insufficient solubility in tris buffer. Plasmid DNA fragmentation studies of IBF and complexes 1 , 2 and 5 indicate that they cleaved the pBR322 plasmid potentially. Further, the drugs IBF {2-[4-(2-methylpropyl)phenyl]propanoic acid}, MESNA (sodium 2-mercaptoethane-sulfonate), warfarin [2H-1-benzopyran-2-one,4-hydroxy-3-(3-oxo-1-phenylbutyl)], sulindac (2-{5-fluoro-1-[(4-methanesulfinylphenyl) methylidene]-2-methyl-1H-inden-3-yl}acetic acid) and their corresponding organotin(IV) complexes 1–19 (complexes 6–19 were synthesized/reported previously) were screened in vitro for cytotoxicity against human cancer cell lines viz. DU145 (prostate cancer), HCT-15 (colon adenocarcinoma), Caco-2 (colorectal adenocarcinoma), MCF-7 (mammary cancer), LNCaP (androgen-sensitive prostate adenocarcinoma) and HeLa (cervical cancer), through MTT reduction assay and the cause of cell death was investigated through acridine orange/ethidium bromide staining of cells and DNA fragmentation assay. The probable structure–cytotoxicity relationship is also discussed. The major role of apoptosis along with small necrosis was also validated by flow cytometry assay using annexin V–fluorescein isothiocyanate and propidium iodide analysis. 相似文献
160.
Poonam Gupta Dr. Durga Prasad Karothu Dr. Ejaz Ahmed Prof. Panče Naumov Prof. Naba K. Nath 《Angewandte Chemie (International ed. in English)》2018,57(28):8498-8502
The first example of a smart crystalline material, the 2:1 cocrystal of probenecid and 4,4′‐azopyridine, which responds reversibly to multiple external stimuli (heat, UV light, and mechanical pressure) by twisting, bending, and elastic deformation without fracture is reported. This material is also able to self‐heal on heating and cooling, thereby overcoming the main setbacks of molecular crystals for future applications as crystal actuators. The photo‐ and thermomechanical effects and self‐healing capabilities of the material are rooted in reversible trans–cis isomerization of the azopyridine unit and crystal‐to‐crystal phase transition. Fairly isotropic intermolecular interactions and interlocked crisscrossed molecular packing secure high elasticity of the crystals. 相似文献