For the synthesis of 2,7-diamino-9,9-bis(4-aminophenyl)fluorene2, first 2,7-dinitro-9,9-bis(4-aminophenyl)fluorene 1 was synthesized by the reaction of 2,7-dinitro-9-fluorenone with aniline and aniline hydrochloride. 2 was obtained by the reduction of 1 with hydrazine hydrate and 10% palladium on carbon. 相似文献
Aromatic, aliphatic and sterically hindered amines react smoothly with commercially available N, N'-bis-BOC-S-methylisothiourea 2 in the presence of mercury chloride to give the protected guanidine in good yield. It is particularly noteworthy that 2 can also be employed in a straightforward, two-step synthesis of monoaryl internal guanidines. 相似文献
A further study of the alkaloid constituents of Aconitum forrestii led to the isolation of three new C19‐diterpenoid alkaloids, named 14‐acetoxy‐8‐O‐methylsachaconitine ( 1 ), 14‐acetoxyscaconine ( 2 ), and 8‐O‐ethylcammaconine ( 3 ). Their structures were determined by UV, IR, and MS, 1D‐ and 2D‐NMR analyses. 相似文献
In this article, a new method that utilizes a diethyldithiocarbamate-modified nanometre TiO2 (TiO2–DDTC) as solid-phase extractant has been developed for simultaneous preconcentration of trace Cu(II), Pb(II), Zn(II), and Cd(II) prior to measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). The separation/preconcentration conditions of analytes, which include the effects of pH, sample flow rate and volume, elution conditions, and interfering ions on the recovery of the analytes, were investigated. At pH 5, the adsorption capacity of modified nanometre TiO2–DDTC was found to be 6.2, 19, 4.7, and 6.0?mg/g for Cu(II), Pb(II), Zn(II), and Cd(II), respectively. According to the definition of IUPAC, the detection limits (3σ) of this method for Cu(II), Pb(II), Zn(II), and Cd(II) were 0.41, 1.7, 0.39, and 0.52?ng/mL, respectively. The proposed method achieved satisfied results when applied to the determinations of trace Cu(II), Pb(II), Zn(II), and Cd(II) in biological and natural water samples. 相似文献
A series of novel red phosphorescent polymers is successfully developed through Suzuki cross‐coupling among ambipolar units, functionalized IrIII phosphorescent blocks, and fluorene‐based silane moieties. The photophysical and electrochemical investigations indicate not only highly efficient energy‐transfer from the organic segments to the phosphorescent units in the polymer backbone but also the ambipolar character of the copolymers. Benefiting from all these merits, the phosphorescent polymers can furnish organic light‐emitting diodes (OLEDs) with exceptional high electroluminescent (EL) efficiencies with a current efficiency (ηL) of 8.31 cd A−1, external quantum efficiency (ηext) of 16.07%, and power efficiency (ηP) of 2.95 lm W−1, representing the state‐of‐the‐art electroluminescent performances ever achieved by red phosphorescent polymers. This work here might represent a new pathway to design and synthesize highly efficient phosphorescent polymers.
The photo-induced ultrafast electron dynamics in both anatase and rutile TiO\begin{document}$_{2}$\end{document} are investigated by using the Boltzmann transport equation with the explicit incorporation of electron-phonon scattering rates. All structural parameters required for dynamic simulations are obtained from ab initio calculations. The results show that although the longitudinal optical modes significantly affect the electron energy relaxation dynamics in both phases due to strong Fr?hlich-type couplings, the detailed relaxation mechanisms have obvious differences. In the case of a single band, the energy relaxation time in anatase is 24.0 fs, twice longer than 11.8 fs in rutile. This discrepancy is explained by the different diffusion distributions over the electronic Bloch states and different scattering contributions from acoustic modes in the two phases. As for the multiple-band situation involving the lowest six conduction bands, the predicted overall relaxation times are about 47 fs and 57 fs in anatase and rutile, respectively, very different from the case of the single band. The slower relaxation in rutile is attributed to the existence of multiple rate-controlled steps during the dynamic process. The present findings may be helpful to control the electron dynamics for designing efficient TiO\begin{document}$_{2}$\end{document}-based devices. 相似文献
Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of~(25)Mg(p,γ)~(26)Al,~(19)F(p,α)~(16)O,~(13)C(α,n)~(16)O and ~(12)C(α,γ)~(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given. 相似文献