共查询到20条相似文献,搜索用时 93 毫秒
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用密度泛函理论(DFF)的B3LYP方法,在6-311G^ 水平上对AIPm和AIPm^-(m=2~9)团簇的几何构型,电子结构和振动频率等性质进行了理论研究,给出了一种以P朋团簇作为设计AIPm类结构的母体,考虑在不同位置上结合Al原子的结构,可以较快找到AIPm类团簇基态结构的方法.通过对基态结构的第一离解能和能量二次差分讨论,得到m为奇数的AIPm团簇比m为偶数的稳定,对基态结构的HOMO-LUMO能隙和绝热电子亲合势的讨论表明,AIP3^-,AIP5和AIP7团簇结构较稳定。 相似文献
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根据遗传算法的基本原理,建立了一种优化分子几何结构的理论计算程序,对用Lennard-Jones势描述的惰性气体分子LJ38的结构进行了优化计算,并进一步计算了其结构的拓扑指数.结果显示出LJ38分子基态结构具有奇特的和文献报等不一致的反常拓扑性质. 相似文献
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噻菁染料的合成及吸收光谱的研究 总被引:1,自引:0,他引:1
合成了阳离子型、两性离子型和阴离子型的噻菁染料,对它们的结构进行了表征,并研究了染料的结构(阴离子和取代基的改变) 对吸收光谱的影响。 相似文献
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含Sn—N键的混合三烃基锡氮杂环化合物的研究 总被引:1,自引:0,他引:1
报道了15个含Sn-N键的混合三烃基锡环衍生物合成及结构表征。随含氮杂环的不同。化合物分别是五配位的聚合结构和四配位的单体结构,对化合物的质谱作了较为详细的讨论,测定了化合物的生物活性,并对生物活性与结构的关系进行了讨论。 相似文献
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M. B. Berezin A. V. Kustov D. B. Berezin N. G. Manin 《Russian Journal of General Chemistry》2013,83(1):106-109
Deuteroporphyrin and hematoporphyrin as complete methyl esters and their complexes with iron(III) were synthesized and characterized by NMR and electronic spectroscopy. For the first time the changes of the specific heat capacity of these solid biological objects with temperature were investigated by the method of differential scanning calorimetry. These parameters are shown to be smooth functions of temperature in the range 290–360 K, indicating the absence of the phase transitions in these systems. 相似文献
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以氯化血红素(Ⅰ)为原料,经过溴化氢-冰醋酸加成反应、羟基亲核取代反应和无水氯化氢催化酯化反应制得3,8-双-(1-羟基乙基)次卟啉二甲酯(Ⅲ),然后通过琼斯试剂氧化反应制备了3,8-双乙酰基次卟啉二甲酯(Ⅳ)。 考察了血红素与溴化氢-冰醋酸饱和溶液反应过程中温度和时间对3,8-双-(1-羟基乙基)次卟啉二甲酯(Ⅲ)产率的影响;改进了酯化反应的实验条件;选用了廉价易得、选择性较好的羟基选择性氧化剂。 实验结果表明,当反应温度为35 ℃、反应时间为25 h时,血卟啉(Ⅱ)的产率最高,为98.5%;当催化剂为无水氯化氢时产物(Ⅲ)的产率最高,为72.1%;使用琼斯试剂做氧化剂使实验成本大大降低。 通过1H NMR、MS和IR测试技术对产物结构进行了表征。 相似文献
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The hematoporphyrin derivative YHPD, a China-made product, has been clinically used in photodynamic therapy of tumors as a good photosensitizing drug. The NMR study on the structure of its major components is reported here. In terms of high performance liquid chromatography (HPLC) four major components A, B, C and D were isolated. The NMR results showed that the component A is O-acetylhematoporphyrin, B and C are two isomers of vinyldeuteroporphyrin. The spectra of 2-dimensional homonuclear correlation NMR, 2-dimensional NOE (nuclear overhauser enhancement), ~(13)C-NMR and off-resonance as well as FAB (fast atom bombarding) mass spectrum of component D indicate that it is a protoporphyrin dimer linked by carbon-carbon bond. This finding may providea chemical basis for understanding the difference in biological activity between YHPD and other foreign commercial HPD, as well as the composition of clincally used alkali-treated HPD and its effective component. 相似文献
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Y X Fu X Shen Q M Li Y J Zhang 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(4):442-457
The hematoporphyrin derivative YHPD, a China-made product, has been clinically used in photodynamic therapy of tumors as a good photosensitizing drug. The NMR study on the structure of its major components is reported here. In terms of high performance liquid chromatography (HPLC) four major components A, B, C and D were isolated. The NMR results showed that the component A is O-acetylhematoporphyrin, B and C are two isomers of vinyldeuteroporphyrin. The spectra of 2-dimensional homonuclear correlation NMR, 2-dimensional NOE (nuclear overhauser enhancement), 13C-NMR and off-resonance as well as FAB (fast atom bombarding) mass spectrum of component D indicate that it is a protoporphyrin dimer linked by carbon-carbon bond. This finding may provide a chemical basis for understanding the difference in biological activity between YHPD and other foreign commercial HPD, as well as the composition of clinically used alkali-treated HPD and its effective component. 相似文献
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A. Andreoni R. Cubeddu S. De Silvestri P. Laporta G. Jori E. Reddi 《Chemical physics letters》1982,88(1):33-36
Absorption and fluorescence properties of hematoporphyrin derivative in different solvent systems are investigated. The presence of a large amount of stable aggregates is demonstrated. The existence of these aggregates represents one major difference between hematoporphyrin derivative and hematoporphyrin free base. 相似文献
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A F Mironov A N Nizhnik A Y Nockel 《Journal of photochemistry and photobiology. B, Biology》1990,4(3):297-306
The oligomeric composition of HpD, Photofrin II and other hematoporphyrin derivatives useful for the diagnosis and therapy of tumors has been studied. Gel chromatographic procedures were used that excluded porphyrin aggregation. Photofrin and hematoporphyrin derivatives were shown to contain different quantities of monomer, dimer and other oligomeric porphyrins. 相似文献
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PROPOSED STRUCTURE OF THE TUMOR-LOCALIZING FRACTION OF HPD (HEMATOPORPHYRIN DERIVATIVE) 总被引:1,自引:0,他引:1
Abstract— Synthesis of the tumor-localizing preparation HPD (hematoporphyrin derivative) results in the formation of dimers and oligomers of hematoporphyrin joined by labile linkages. Studies with HPD and an HPD analog containing the chlorin analog of mesoporphyrin suggest the presence of two different linkages, either of which yields a tumor-localizing product. One such linkage is apparently derived from a hematoporphyrin-based oligomer present in commercial preparations of hematoporphyrin as an impurity. The other linkage is formed during the chemical steps leading to the conversion of hematoporphyrin to "HPD". 相似文献
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G J Smith 《Journal of photochemistry and photobiology. B, Biology》1992,12(1):29-36
A long-lived transient with a lifetime of several hundred microseconds was observed following the flash photolysis of aqueous solutions of hematoporphyrin buffered at pH 7.5. The transient-ground state difference absorption spectrum was determined 500 microseconds after flash photolysis. The yield of this species was found to increase with increasing hematoporphyrin concentration and it was also found to depend on the excitation wavelength. The lifetime of the species is not significantly affected by the presence of oxygen. Because the triplet state of hematoporphyrin is not the only long-lived species produced by flash photolysis of aqueous hematoporphyrin solutions, the observed triplet state extinction coefficients will be lower than the true value and hence the triplet state yields of hematoporphyrin determined by the flash photolysis, "complete conversion" technique, are only upper limits. The formation of the long-lived species is discussed in terms of electron transfer between the monomer partners in hematoporphyrin dimer and aggregates which are present in aqueous solutions of hematoporphyrin, particularly in concentrated solutions. 相似文献