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131.
H and 13C NMR spectra were recorded for some novel picrate derivatives derived from 3,3-dimethyl-2,6-diarylpiperidin-4-ones and 3-benzyl-2,6-diarylpiperidin-4-one.
The photophysical properties of the picrate derivatives were studied in several solvents, which include a wide range of apolar,
polar and protic media. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation
rate constant. This is attributed due to the presence of increased electrostatic interaction between N-protonated piperidone
ring and picryl anion ring so that the picryl anion ring lies perpendicular to the plane of the N-protonated piperidone ring
i.e., non co-planarity. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption
and reemission effects in the detected emission in highly concentrated solutions. The higher fluorescence quantum yield of
the picrate derivatives are observed in polar media. 相似文献
132.
L.?CampbellEmail author H.?Tanaka H.?Kato S.?Jayaraman M.?J.?Brunger 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(1):26
Recent measurements of integral cross sections for electron impact excitation of the
Schumann-Runge continuum, longest band and second band of molecular oxygen are applied to
calculations of emissions from the atmosphere of Europa. Molecules excited to these bands
predissociate, producing O(1D) (excited oxygen) atoms which subsequently decay
to produce 630.0-nm radiation. Radiation of this wavelength is also produced by direct
excitation of O atoms and by the recombination of O
\hbox{2+_2^+}
+
2
with electrons, but these two processes also produce O(1S) atoms which then
emit at 557.7 nm. It is shown by modeling that the ratio of 630.0-nm to 557.7-nm is
sensitive to the relative importance of the three processes, suggesting that the ratio
would be a useful remote sensing probe in the atmosphere of Europa. In particular, the
excitation of the Schumann-Runge continuum, longest band and second band is produced by
magnetospheric electrons while the recombination is produced by secondary electrons
produced in the atmosphere. This difference raises the possibility of determination of the
secondary electron spectrum by measurement of light emissions. 相似文献
133.
Organic‐inorganic hybrids based on phenanthrene‐functionalized gold nanoparticles for OLEDs
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Jayabharathi Jayaraman Abirama Sundari Ganapathy Venugopal Thanikachalam Jeeva Palanivel Panimozhi Sekar 《Journal of Physical Organic Chemistry》2018,31(5)
The electroluminescence intensity of the phenanthrene‐functionalized gold nanoparticles, PMPT‐Au nanoparticles/CPB: Ir(PIA)2 (acac) film, was increased by 4.9 times compared with control device, CPB: Ir(PIA)2 (acac) due to coupling between the excitons of emissive layer and localized surface plasmonic resonance of PMPT‐Au NPs. The maximum luminous efficiencies of devices II to IV with PMPT‐Au NPs were 39.2 cd A?1 (11.8 V), 40.1 cd A?1 (10.5 V), and 43.1 cd A?1 (9.0 V), respectively. The increment of current efficiency with PMPT‐Au NP coated devices was strongly related to the energy transfer between the radiated light generated from CBP: Ir(PIA)2 (acac) emissive layer and localized surface plasmonic resonance excited by PMPT‐Au NP layer. 相似文献
134.
Noor Shahina Begum D. E. Vasundhara C. R. Girija M. Narendra Mallya Gopalpur Nagendrappa 《Journal of chemical crystallography》2008,38(7):547-551
Abstract The crystal and molecular structure of cis-1-chloro-2-amino-1-trimethylsilylcycloheptane picrate (cis-CATP) is determined and discussed along with its spectroscopy. The crystal structure of this compound (C10H23SiClN+ C6H2N3O7−) consists of ammonium cycloheptane cation and picrate anion stabilized by interionic N–H···O and C–H···O interactions leading
to extended hydrogen bonded network structure. Apart from the less common syn addition of nitrosylchloride to 1-trimethylsilylcycloheptene ring, an interesting and unexpected reversal of regiochemistry
of addition is revealed.
Index Abstract The preparation of cis-1-chloro-2-ammonium-1-trimethylsilylcycloheptane picrate is described and its crystal structure is determined and discussed.
相似文献
135.
Debabrata Dhara Arumugam Jayaraman Marcel Hrterich Rian D. Dewhurst Holger Braunschweig 《Chemical science》2022,13(19):5631
While a stable base-free arylalumylene bearing a sterically encumbered terphenyl substituent has been reported previously, we herein report that our attempts to form a base-stabilised arylalumylene bearing a relatively small terphenyl substituent and an N-heterocyclic carbene base led instead to a “masked” dialumene (LRAl AlRL), self-stabilised by one peripheral aromatic group. Intriguingly, examining the behavior of this species or its transient dialumene formed from reducing the diiodoarylalane in aromatic solvents under different conditions reveals that they both decouple into the desired base-stabilised arylalumylene. This transient acyclic, dicoordinate alumylene is highly reactive, deconstructing benzene and toluene to furnish dialuminium derivatives of pentalene, providing the first example of a neutral AlI compound able to deconstruct these less reactive arenes. Computational insights were also gained on the dialumene dissociation and on the mechanism of arene deconstruction by alumylene.Attempts to form a base-stabilised arylalumylene by reducing an NHC-coordinated diiodoterphenylalane led to a masked dialumene. Reactivity studies showed it decouples to initially aimed arylalumylene, which easily deconstructs less reactive arenes. 相似文献
136.
Inside Back Cover: Programmed Photodegradation of Polymeric/Oligomeric Materials Derived from Renewable Bioresources (Angew. Chem. Int. Ed. 4/2015)
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137.
138.
Tyler B. Martin Arthi Jayaraman 《Journal of polymer science. Part A, Polymer chemistry》2014,52(24):1661-1668
We present a simulation study showing the effect of bidispersity in matrix homopolymer length on the wetting/dewetting of homopolymer-grafted nanoparticles and the morphology of polymer nanocomposites where the graft and matrix polymer chemistries are identical. In a bidisperse matrix with equal number of short and long chains and average matrix length greater than the monodisperse graft length, the densely grafted polymer layer is preferentially wet by the short chains and relatively dewet by the long chains. This is driven by a larger gain in entropy of mixing between graft and matrix for short matrix chains than long matrix chains. Despite the preferential wetting of the short and dewetting of long chains, matrix length bidispersity does not significantly change the overall wetting of the grafted layer. Unlike graft length bidispersity that significantly improves particle dispersion, matrix length bidispersity slightly increases particle aggregation in the polymer matrix. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1661–1668 相似文献
139.
The effect of pressure on the Raman modes in TeO2 (paratellurite) has been investigated to 30GPa, using the diamond cell and argon as pressure medium. The pressure dependence
of the Raman modes indicates four pressure-induced phase transitions near 1 GPa, 4.5 GPa, 11 GPa and 22 GPa. Of these the
first is the well studied second-order transition fromD
4
4
symmetry toD
2
4
symmetry, driven by a soft acoustic shear mode instability. The remarkable similarity in the Raman spectra of phases I to
IV suggest that only subtle changes in the structure are involved in these phase transitions. The totally different Raman
spectral features of phase V indicate major structural changes at the 22GPa transition. It is suggested that this high pressure-phase
is similar to PbCl2-type, from high pressure crystal chemical considerations. The need for a high pressure X-ray diffraction study on TeO2 is emphasized, to unravel the structure of the various high pressure phases in the system. 相似文献