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481.
Chesman AS Yang M Mallick B Ross TM Gass IA Deacon GB Batten SR Mudring AV 《Chemical communications (Cambridge, England)》2012,48(1):124-126
The complexes (N(4444))(3)[Ln(dcnm)(6)] (Ln = La-Nd, Sm; N(4444) = tetrabutylammonium) display a decrease in the melting point upon fast cooling from a melt, which is shown by in situ synchrotron based X-ray powder diffraction to be due to the formation of a second, less thermodynamically stable, polymorph. 相似文献
482.
The carbophosphazene and cyclophosphazene hydrazides, [{NC(N(CH(3))(2))}(2){NP{N(CH(3))NH(2)}(2)}] (1) and [N(3)P(3)(O(2)C(12)H(8))(2){N(CH(3))NH(2)}(2)] were condensed with o-vanillin to afford the multisite coordination ligands [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-OH)(m-OCH(3))}(2)}] (2) and [{N(2)P(2)(O(2)C(12)H(8))(2)}{NP{N(CH(3))N═CH-C (6)H(3)-(o-OH)(m-OCH(3))}(2)}] (3), respectively. These ligands were used for the preparation of heterometallic complexes [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuCa(NO(3))(2)}] (4), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{Cu(2)Ca(2)(NO(3))(4)}]·4H(2)O (5), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(4)}]·CH(3)COCH(3) (6), [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(3)}] (7), and [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuTb(NO(3))(3)}] (8). The molecular structures of these compounds reveals that the ligands 2 and 3 possess dual coordination pockets which are used to specifically bind the transition metal ion and the alkaline earth/lanthanide metal ion; the Cu(2+)/Ca(2+), Cu(2+)/Tb(3+), and Cu(2+)/Dy(3+) pairs in these compounds are brought together by phenoxide and methoxy oxygen atoms. While 4, 6, 7, and 8 are dinuclear complexes, 5 is a tetranuclear complex. Detailed magnetic properties on 6-8 reveal that these compounds show weak couplings between the magnetic centers and magnetic anisotropy. However, the ac susceptibility experiments did not reveal any out of phase signal suggesting that in these compounds slow relaxation of magnetization is absent above 1.8 K. 相似文献
483.
Biplab K. Bera Subala Mondal Subhasis Mallick Arup Mandal Parnajyoti Karmakar Alak K. Ghosh 《Journal of solution chemistry》2012,41(4):741-753
The kinetics of the interaction of three glycine-containing dipeptides, namely, glycyl-L-valine (L1-L??H), glycyl-glycine (L2-L??H) and glycyl-L-glutamine (L3-L??H), with [Rh(H2O)5OH]2+ has been studied spectrophotometrically in aqueous medium as a function of the Rh(H2O)5OH2+ and dipeptide concentrations, pH and temperature, at constant ionic strength. At pH = 4.3, the substrate complex exists predominantly as the hydroxopentaaqua species and dipeptides as zwitterions. The reaction has been found to proceed via two parallel paths: both processes are ligand dependent. The rate constants for the processes are of the order: k 1??10?3 s?1 and k 2??10?5 s?1. The activation parameters for both steps were evaluated from Eyring plots. Based on the kinetic and activation parameters an associative interchange mechanism is proposed for both of the interaction processes. The low $\Delta H_{1}^{\neq}$ and $\Delta H_{2}^{\neq}$ values and large negative values of $\Delta S_{1}^{\neq}$ and $\Delta S_{2}^{\neq}$ support the associative mode of activation for both processes. The product of the reaction has been characterized using IR and ESI-mass spectroscopic analysis. 相似文献
484.
Sourov Chandra Sourav Bag Pradip Das Dipsikha Bhattacharya Panchanan Pramanik 《Chemical physics letters》2012
One step solvothermal route has been developed to prepare a well dispersed magnetically separable palladium–graphene nanocomposite, which can act as a unique catalyst against hydrogenation due to the uniform decoration of palladium nanoparticles throughout the surface of the magnetite–graphene nanocomposite and hence can be reused for several times. In addition to catalytic activity, palladium nanoparticles also facilitate the formation and homogeneous distribution of magnetite (Fe3O4) nanoparticles onto the graphene surfaces or else an agglomerated product has been obtained after the solvothermal reduction of graphene oxide in presence of Fe3+ alone. 相似文献
485.
The ultrasonic wave propagation in sinusoidally corrugated waveguides is studied in this paper. Periodically corrugated waveguides are gaining popularity in the field of vibration control and for designing structures with desired acoustic band gaps. Currently only numerical method (Boundary Element Method or Finite Element Method) based packages (e.g., PZFlex) are in principle capable of modeling ultrasonic fields in complex structures with rapid change of curvatures at the interfaces and boundaries but no analyses have been reported. However, the packages are very CPU intensive; it requires a huge amount of computation memory and time for its execution. In this paper a new semi-analytical technique called Distributed Point Source Method (DPSM) is used to model the ultrasonic field in sinusoidally corrugated waveguides immersed in water where the interface curvature changes rapidly. DPSM results are compared with analytical solutions. It is found that when a narrow ultrasonic beam hits the corrugation peaks at an angle, the wave propagates in the backward direction in waveguides with high corrugation depth. However, in waveguides with small corrugation the wave propagates in the forward direction. The forward and backward propagation phenomenon is found to be independent of the signal frequency and depends on the degree of corrugation. 相似文献
486.
Vertebrate segmentation has been proved to be under a strict temporal control governed by a biological clock, known as the segmentation clock. The present experimental evidence suggests that the segmentation clock initiates and maintains its periodic cycle by the periodic activation or inhibition of the Notch signaling pathway as well as the periodic autoregulation of the cyclic genes themselves. In this paper, we investigate the structural and evolutionary properties of the Notch pathway proteins involved in the mice segmentation clock and computationally identify the interaction map within the Notch signaling pathway. The results of our analysis strongly indicate that most of the pathway proteins are intrinsically disordered and that the mechanism of their interaction likely involves helical molecular recognition elements, short loosely structured segments within disordered regions which are directly involved in protein-protein interactions. Predicted interactions are in agreement with gene knock-out studies available in the literature. 相似文献
487.
Recent synthesis of sp-hybridized cyclo[18]carbon allotrope has attracted immense curiosity. Since then, a generous amount of theoretical studies concerning aromaticity, adsorption, and spectra of the molecule have been performed. However, very few stuides have been carried out concerning its reactivities and catalytic behaviour. In this article, a DFT-based inquisition has been reported regarding the reactivity of Si substituted cyclo[18]carbon molecule towards molecular N2. Results show that the Si substituted derivative is effective in producing adducts with molecular nitrogen. Charge calculations and IRC trapping methods indicate that only the Si center of C17Si and its (HOMO-1) level participate in N2 addition. The N-adduct so formed, is then found to spontaneously react with molecular H2. The addition of two H2 molecules to the activated nitrogen molecule to give respective amine derivatives have also been studied. The successful generation of the precursor of NH3 by C17Si lays a clear emphasis on its potentiality. 相似文献
488.
Density functional theory has been used to elucidate the mechanistic underpinnings of the regeneration of ammonia-borane (H3B−NH3, AB ) from polyborazylene (BxNxHx, PBz ) in the presence of hydrazine (H2N−NH2, Hz ). Herein, borazine (B3N3H6, Bz ) is used as the simplest relevant model of PBz for the regeneration process. Digestion of Bz using Hz was found to occur by a string of Lewis acid base adduct (between B atoms of Bz and Hz molecule) formation and Hz assisted proton transfer processes. Later, B−H bonds of HB(NHNH2)2, the Bz digested product, are redistributed to form hydrazine-borane (H3B−NH2NH2, HzB ) and B(NHNH2)3. Redistribution of B−H bonds occurs through hydroboration and concerted proton-hydride transfer. Another B−H redistributed product, B(NHNH2)3, produces HzB as a result of proton and hydride transfer from cis-diazene ( Dz ), the oxidized product of Hz in presence of O2. 相似文献
489.
Firdaus Rahaman Gayen Debashree Bora Dr. Dibyendu Mallick Dr. Abir Sarbajna Dr. Subrata Ghosh Dr. Jayaramudu Jarugala Dr. Biswajit Saha 《欧洲无机化学杂志》2023,26(28):e202300462
Ferrocene functionalized 2-phenylpyridine iridium(III) pentamethylcyclopentadienyl complex is synthesized and probed for oxygen evolution from water. The excellent activity of this system has been rationalized by proposing a Fe(III)/Ir(IV) transient intermediate where bimetallic redox synergism between the Fe and Ir centres possibly provide an alternative pathway rather than a conventional Ir(V) based cycle. 相似文献
490.
Dr. Umme Tamima Dr. Sourav Sarkar Dr. Md Reyazul Islam Anushree Shil Dr. Kyeong Hwan Kim Dr. Ye Jin Reo Dr. Yong Woong Jun Hasanul Banna Soobin Lee Prof. Kyo Han Ahn 《Angewandte Chemie (International ed. in English)》2023,62(15):e202300580
Fluorescence monitoring of ATP in different organelles is now feasible with a few biosensors developed, which, however, show low sensitivity, limited biocompatibility, and accessibility. Small-molecule ATP probes that alleviate those limitations thus have received much attention recently, leading to a few ATP probes that target several organelles except for the nucleus. We disclose the first small-molecule probe that selectively detects nuclear ATP through reversible binding, with 25-fold fluorescence enhancement at pH 7.4 and excellent selectivity against various biologically relevant species. Using the probe, we observed 2.1–3.3-fold and 3.9–7.8-fold higher nuclear ATP levels in cancerous cell lines and tumor tissues compared with normal cell lines and tissues, respectively, which are explained by the higher nuclear ATP level in the mitosis phase. The probe has great potential for studying nuclear ATP-associated biology. 相似文献