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91.
Photochromism of 1′,3′,3′-trimethyl-6-piperidinospiro [indoline-2′,3-3H-naphth [2,1-b][1,4]-oxazine]
The effect of the piperidine substituent on the spectral and photochromic properties of spiro(indoline-naphthoxazines) (SINO) in different solvents is studied. The introduction of this substituent into the naphthoxazine fragment of SINO results in the appearance of fluorescence of the initial formA of SINO at low temperatures. This fluorescence gradually disappears as the temperature increases. The temperature and concentration dependences of the spectral parameters of photoinduced formB of SINO make it possible to assume thatB molecules aggregate in non-polar solvents. In all solvents studied, form B, unlike the photoinduced form of the non-substituted spiro naphthoxazine, is stabilized as a bipolar ion with a positive charge on the nitrogen atom of the piperidine substituent. The increase in the rate of thermal decolorization as the medium polarity increases is explained.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 684–688, April, 1995.The authors are grateful to the Belarus' Foundation for Basic Research for financial support of this work. 相似文献
92.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):149-158
Two Dy–Mn polymers, {[Dy(L1)3Mn1.5(H2O)3]?3.125 H2O}n ( 1 , L1=pyridine‐2,6‐dicarboxylic acid) and {[Dy(L2)3Mn1.5(H2O)6]?8.25 H2O}n ( 2 , L2 = 4‐hydroxylpyridine‐2,6‐dicarboxylic acid), with high symmetry (S6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 Å diameter, while 2 has a honeycomb‐type 2D structure with the cavity of approximately 14.4 Å diameter. In the construction of multidimensional porous polymers with 3d–4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg2+, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg2+ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d–4f metal‐based nanoporous polymer to exhibit luminescent selectivity for Mg2+. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2 . Thermal gravimetric analyses and powder X‐ray diffraction investigations have also been performed, suggestive of high thermal stability of 1 . 相似文献
93.
We have used molecular dynamics simulations to study the physical properties of modified TIP3P water model included in the CHARMM program, using four different methods-the Ewald summation technique, and three different spherical truncation methods-for the treatment of the long-range interactions. Both the structure and dynamics of the liquid water model were affected by the methods used to truncate the long-range interactions. For some of the methods artificial structuring of the model liquid was observed around the cutoff radius. The model liquid properties were also affected by the commonly applied temperature control methods. Four different methods for controlling the temperature of the system were studied, and the effects of these methods on the bulk properties for liquid water were analyzed. The system size was also found to change the dynamics of the model liquid water. Two control simulations with the SPC/E water model were carried out. The self-diffusion coefficient (D), the radial distribution function (g(OO)), the distance dependent Kirkwood G-factor [G(k)(r)] and the intermolecular potential energy (E(pot)) were determined from the different trajectories and compared with the experimental data. 相似文献
94.
The interactions of [Pt(CNN)(4-dpt)]PF(6), (1; 4-dpt=2,4-diamino-6-(4-pyridyl)-1,3,5-triazine, HCNN=6-phenyl-2,2'-bipyridine) with double-stranded DNA, poly(dA-dT)(2), and poly(dG-dC)(2) were examined by spectroscopic, electrophoretic, and hydrodynamic methods. The spectroscopic data were analyzed with McGhee, van't Hoff, and Gibbs-Helmholtz equations. In a comparative study, [Pt(CNN)(py)]PF(6) (2; py=pyridine) was prepared and the nature of its binding towards DNA was investigated [preliminary results: ChemBioChem 2003, 4, 62-68]. For reactions with calf thymus DNA at 20 degrees C, the intrinsic binding constants for 1 and 2 are (4.6+/-0.2)x10(5) and (2.3+/-0.3)x10(4) mol(-1) dm(3), respectively. Results of DNA-binding reactions revealed that 1 and 2 preferentially bind to the AT sequence of duplex DNA. Intercalation is the preferred binding mode for 2, whereas both intercalation and minor-groove binding are observed for 1. Complex 1 is cytotoxic against a number of carcinoma cell lines, including KB-3-1, CNE-3, and HepG2, and remains potent against multidrug- or cisplatin-resistant KB-V-1 and CNE1 cell lines, for which the resistance ratios are 1.6 and 1.5, respectively. Importantly, 1 is almost an order of magnitude less toxic to the normal cell line CCD-19Lu (IC(50)=176+/-1.7 microM) and it selectively induced apoptosis leading to cancer cell death with less than 5 % detectable necrosis. 相似文献
95.
Yoshikuni Uchida Masao Yoshida Osamu Nishiara Kazunori Matsui 《Journal of Sol-Gel Science and Technology》2003,26(1-3):177-180
Silica gels doped with Cu2+ ions were prepared from the (3-aminopropyl) trimethoxysilane (APTMOS)/tetraethoxysilane (TEOS) systems. Sols showed a broad absorption peak at 640 nm, suggesting 3–5 coordination of the aminopropyl groups to Cu2+. For gels prepared from APTMOS and dried at room temperature, the 640 nm peak decreased and a red-shifted absorption appeared below 400 nm within a few months. The luminescence spectra of the xerogels showed emission bands at 430–470 and 510 nm. The former and latter bands are ascribed to Cu+ monomer and dimer emissions, respectively. These results indicate that Cu2+ ions are reduced to Cu+. When xerogels were prepared from APTMOS/TEOS = 1 (vol/vol), the color of xerogels was blue with an absorption peak at around 670 nm, indicating no reduction of Cu2+ ions. 相似文献
96.
低色温高显色性大功率白光LED的制备及其发光特性研究 总被引:2,自引:3,他引:2
用GaN基大功率蓝光LED芯片作为激发光源,分别用荧光粉转换法和红光LED补偿法制备了不同相关色温及显色指数的白光LED。对器件的发光特性研究表明,采用监光LED芯片激发单一黄色荧光粉,虽可以获得光通量和发光效率较高的白光LED,但其色温较高,显色性较差;在黄色荧光粉中添加红色荧光粉,由于光谱中红色成分的增加,可降低器件的色温,并提高器件的显色性,但由于目前红色荧光粉的转换效率较低,致使器件的整体发光效率不高;采用蓝光LED芯片激发黄色荧光粉,同时用红光LED进行补偿,通过调整蓝光和红光LED芯片的工作电流以及荧光粉的用量,可获得低色温和高显色性白光LED,而且整体发光效率较高。 相似文献
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100.
Taisiya S. Sukhikh Evgeny Yu. Filatov Alexey A. Ryadun Konstantin A. Kovalenko Andrei S. Potapov 《Molecules (Basel, Switzerland)》2022,27(19)
A three-component reaction between the 1,4-benzenedicarboxylic (terephthalic) acid (H2bdc), bis(1,2,4-triazol-1-yl)methane (btrm) and zinc nitrate was studied, and three new coordination polymers were isolated by a careful selection of the reaction conditions. Coordination polymers {[Zn3(DMF)(btrm)(bdc)3]·nDMF}∞ and {[Zn3(btrm)(bdc)3]·nDMF}∞ containing trinuclear {Zn3(bdc)3} secondary building units are joined by btrm auxiliary linkers into three-dimensional metal–organic frameworks. The coordination polymer {[Zn(bdc)(btrm)]∙nDMF}∞ consists of Zn2+ cations joined by bdc2− and btrm linkers into a two-fold interpenetrated network. Upon activation, MOF [Zn3(btrm)(bdc)3]∞ demonstrated CO2/N2 adsorption selectivity with an ideal adsorbed solution theory (IAST) factor of 21. All three MOF demonstrated photoluminescence with a maximum near 435–440 nm upon excitation at 330 nm. 相似文献