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71.
Govindasamy Rajarajan Natesan Jayachandramani Subramaniyan Manivarman Jayaraman Jayabharathi Venugopal Thanikachalam 《Transition Metal Chemistry》2008,33(3):393-397
The kinetics of oxidation of aldonitrones by 4-(dimethylamino)pyridinium chlorochromate (DMAPCC) has been studied in aqueous
N,N-dimethylformamide in the presence of perchloric acid. The reaction follows first-order kinetics with respect to each of DMAPCC
and nitrone. The order with respect to [H+] was found to be close to zero. The rate of oxidation was unaltered by the variation of [NaClO4] but addition of MnSO4 decreased the rate. The reaction rate was found to decrease with a decrease in dielectric constant of the medium. Electron-releasing
and electron-withdrawing groups perturb the reaction rate with a good Hammett correlation. The oxidation products were found
to be benzaldehyde and nitrosobenzene. The reaction was carried out at four different temperatures and the activation parameters
have been calculated. On the basis of the experimental findings, a suitable mechanism has been proposed. 相似文献
72.
Mixed-ligand diorganotin esters, [R 2Sn(OP(O)(OH)Ph)(OS(O) 2R (1))] n [R = n-Bu, R (1) = Me ( 1), n-Pr ( 2); R = Et, R (1) = Me ( 3)], have been synthesized by reacting the tin precursors, R 2Sn(OR (1))OS(O) 2R with an equimolar amount of phenylphosphonic acid under mild conditions (room temperature, 6-8 h, CH 2Cl 2). These have been characterized by IR, multinuclear ( (1)H, (13)C{ (1)H}, (31)P, and (119)Sn) NMR, and single crystal X-ray diffraction studies. The asymmetric unit of 1 is comprised of a tetramer with four crystallographically unique tin atoms. The structure reveals a central eight-membered (Sn-O-S-O) 2 cyclic ring with two exocyclic tin atoms, which results from micro 3-binding of the two methanesulfonate groups. The remaining two sulfonates are monodentate and contribute in O...HO(P) hydrogen bonding. The molecular structure is extended into a 3D coordination polymer with the aid of hydrogenphenylphosphonate group on each tin atom, acting in a micro 2-O 2P mode and forms a series of eight-membered (Sn-O-P-O) 2 rings in the structural framework. 2 and 3 are isostructural and represent linear 1D coordination polymers via micro 2-binding mode of both alkanesulfonate and hydrogenphenylphosphonate groups. 相似文献
73.
Sulekh?ChandraEmail author Archana?Gautam Monika?Tyagi 《Transition Metal Chemistry》2007,32(8):1079-1084
Cobalt(II), nickel(II) and copper(II) complexes are synthesized with 1,3,7,9-tetraaza- 4,6,10,12-tetraphenyl-2,8-dithiacyclododecane,
a tetradentate ligand (L) and characterized by elemental analysis, molar conductance measurements, magnetic susceptibitity
measurements, mass, i.r., electronic and e.p.r. spectral studies. All the complexes are non-electrolytes so they may be formulated
as [M(L)X2] [where, M = Co(II), Ni(II) and Cu(II) and X = Cl− and NO
3
−
]. All the complexes are of high spin type. On the basis of i.r., electronic and e.p.r. spectral studies an octahedral geometry
has been assigned for Co(II) and Ni(II) complexes and tetragonal geometry for Cu(II) complexes. The antimicrobial activities
of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against two different species of bacteria and plant pathogenic fungi. 相似文献
74.
Tiwari A Dantelle G Porfyrakis K Taylor RA Watt AA Ardavan A Briggs GA 《The Journal of chemical physics》2007,127(19):194504
Low temperature photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy of high purity ErSc(2)N@C(80) and Er(2)ScN@C(80) fullerenes reveal at least two metastable configurations of the Er(3+) ion within the cage, consistent with previous observations from x-ray diffraction. Using PLE measurements at a number of different emission wavelengths we have characterized the ground state, (4)I(152), and the first excited state, (4)I(132), of the various Er(3+) configurations and their crystal-field splitting. We present detailed energy level diagrams for the ground and excited states of the two dominant configurations of ErSc(2)N@C(80) and Er(2)ScN@C(80). 相似文献
75.
181Ta time differential perturbed angular correlation (TDPAC) and positron lifetime measurements were carried out on homogeneously
α-implanted CuHf samples. TDPAC measurements indicate the trapping of vacancy clusters and helium associated defect complexes
by Hf atoms. The presence of helium-vacancy complexes and helium stabilised voids has been identified by positron lifetime
measurements. Further the nucleation and growth stages of helium bubbles have been identified. TDPAC and positron lifetime
measurements indicate that Hf atoms act as heterogeneous nucleating centers for helium bubbles. Hf atoms are found to suppress
the bubble growth in CuHf as indicated by the results of positron lifetime measurements. 相似文献
76.
77.
Nondoped blue fluorescent OLED based on cyanophenanthrimidazole‐styryl‐triphenylamine/carbazole materials
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Thanikachalam Venugopal Jeeva Palanivel Jayabharathi Jayaraman 《Journal of Physical Organic Chemistry》2017,30(12)
New 2‐(4′‐9H‐carbazole‐9‐yl)‐styryl‐1H‐phenathro[9,10‐d]imidazole‐1‐yl)benzonitrile (SPICN‐Cz) and 4‐(2‐(4‐(diphenylamino)phenyl‐styryl‐1H‐phenathro[9,10‐d]imidazole‐1‐yl)benzonitrile (SPICN‐TPA) have been synthesised, and their photophysical, electrochemical, and electroluminescent properties were analysed in comparison with their cyano‐free parent compounds, SPI‐Cz, and SPI‐TPA. Solvatochromic effects show the transformation of an excited state character from locally excited (LE) state to charge transfer (CT) state. Using time‐dependent density functional theory calculation, the excited state properties of these donor‐acceptor blue emissive materials have been analysed. Their excited state properties have been tuned by replacing the strong donor triphenylamine to weak donor carbazole to achieve the combination of high photoluminance efficiency locally excited (LE) component and high exciton‐utilizing CT component in one excited state. Hybridization processes between LE and CT components of SPICN‐Cz and SPICN‐TPA in the emissive state have been discussed. The nondoped organic light emitting diode device based on SPICN‐Cz exhibit better electroluminescent performances than those of SPICN‐TPA–based device: high external quantum efficiency of 2.58 %, current efficiency of 2.90 cd A‐1, and power efficiency of 2.26 lm W‐1 with Commission Internationale de l'Éclairage (CIE) coordinates of (0.15, 0.12). The excited state modulation and the composition of LE and CT states in the donor‐acceptor system could be useful to design low‐cost, high‐efficiency fluorescent organic light emitting diode materials. 相似文献
78.
79.
K.C. Vishnubhatla S. Venugopal Rao R. Sai Santosh Kumar Maurizio Ferrari D. Narayana Rao 《Optics Communications》2009,282(23):4537-4542
Herein we present results on the femtosecond laser direct writing and optical characterization studies of two dimensional gratings in fused silica, GE 124, and Foturan™ glasses. Varieties of structures were achieved with varying input energy and spatial orientation of the samples. Various characterization techniques including fluorescence spectroscopy, micro-Raman spectroscopy, and laser confocal microscopy were employed to analyze the structural and physical modifications at the focal volume resulting in change of refractive index. Diffraction efficiencies of 9–12% were observed from the grating structures. A broad-band emission was observed in the laser-modified region of the Foturan glass. The obtained results are analyzed in the light of recent work in similar glasses and exploring the applications of such structures in the fields of photonics. 相似文献
80.
Sandeep V.Khansole Shivaji B.Patwari Archana Y.Vibhute Yeshwant B.Vibhute 《中国化学快报》2009,20(3):256-260
The new chromium(Ⅵ) oxidizing reagent isoquinolinium bromochromate(IQBC) was prepared and characterized.The IQBC has been found to be stable and an efficient solid reagent which can be easily prepared in good yield.It act as an efficient brominating reagent for hydroxylated aromatic compounds as well as good oxidizing reagent for the conversion of alcohols to carbonyl compounds in good to excellent yield.The synthesized isoquinolinium bromochromate is more ideal reagent,with number of specification inclu... 相似文献