PHOTOVOLTAIC ACTION SPECTRA AND EFFICIENCIES OF CHLOROPHYLL a SPECIES ABSORBING NEAR 700 nm

Abstract— Alcohol vapors affect the photovoltaic properties of anhydrous chlorophyll a (Chi a). At 23°C, a photovoltaic cell of the type Allanhydrous Chi a|Ag has been successively submitted to non saturating vapors of methanol, ethanol, 1-propanol, 2-propanol, cyclopropyl carbinol, cyclopentanol, methyl cyclopropyl carbinol, 1-butanol, 1-pentanol and chloroethanol. The action spectrum of anhydrous Chi a has a maximum in the red at 672 nm. This maximum is shifted towards 700 nm under the influence of alcohol vapors. The most important changes occur for ethanol, 1-propanol and 2-propanol. In the same way, the conversion efficiencies of light energy into electrical energy, measured at the maximum in the red are, for the same alcohols, higher than the initial value 1.7 times 10^-2% obtained on the average for anhydrous Chi a. A maximum value of 6.3 times 10^-2% has been obtained after rehydration of Chi a solvated with 2-propanol. The influence of alcohol vapors has been interpreted in terms of microcapillarity of anhydrous Chi a and a mean microcavity radius of 11 ± 6 Å has been deduced from the photocurrent variation with the amount of alcohol vapor present in the measuring area. Furthermore, the action spectrum shift towards 700 nm has been interpreted by the formation, at 23°C, of Chi a special aggregates whose action spectrum has been obtained by difference. Infrared spectroscopy demonstrated that anhydrous Chi a obtained from electrodeposition is an assembly of Chi a dimers and that alcohol vapors, producing the special aggregates formation at 23°C, induce a decrease of the free C=O ketone band and an increase of the associated C=O ketone. The C=O esters band is not affected by the Chi a reorganization.     

EVIDENCE FOR THE FORMATION OF A CHLOROPHYLL a/ZEAXANTHIN COMPLEX IN LECITHIN LIPOSOMES FROM FLUORESCENCE DECAY KINETICS

The interaction of Chi a with zeaxanthin (Zea), which is an analogue of lutein, has been studied in soya bean lecithin liposomes using the fluorescence of Chi as monitor. The fluorescence emission spectrum at 4.2 K of Chi a showed characteristic changes in the presence of Zea: the emission maximum shifted from 688 nm to 680 nm, and a peak at 731 nm appeared. The fluorescence decay kinetics of Chi a alone could be described by the sum of two exponential components (T₁,≅0.8 ns, T₂≅2.5 ns). In the presence of Zea a component with a long lifetime, T≅5 ns, appeared with a large relative amplitude (40%). This indicated the formation of a Chl a /Zea complex, in which Chl a /Chl a interaction is negligible, presumably because of strong interaction between Chl a and Zea. The fluorescence anisotropy decay kinetics supported the hypothesis of the formation of a large Chl a containing complex in the presence of Zea. A rotational correlation time, φ≅14 ns at 4°C and φ≅21 ns at 30°C, was found, which is distinctly larger than for samples containing Chl a only. We interpret these results as further evidence for a strong interaction between Chl a and Zea in the hydrophobic environment of the lecithin liposomes. This interaction may also occur in the Chl-proteins of the Chi alb light-harvesting complex of plant photosynthesis.     

ON THE NATURE OF THE INTERMEDIATE ELECTRON ACCEPTOR (A1) IN THE PHOTOSYSTEM I REACTION CENTER

Abstract— A sodium dodecyl sulfate-Photosystem I (PSI) complex has been prepared and characterized with respect to its electron acceptors. Component X and iron-sulfur centers A and B are absent from this preparation but the intermediate electron acceptor (A₁) is present. Flash-induced absorbance changes at 25°C show charge separation, followed by a back-reaction with a half-time of 5 µs. The spectrum of the flash-induced change from 350 to 550 nm indicates a contribution from the intermediate electron acceptor, A₁, as well as from P700⁺. EPR studies show that A₁ is associated with a free-radical signal having a g-value of 2.0025 and a linewidth of 12 gauss. A, would appear to be associated with a monomeric form of either Chi α or pheophytin a.     

吗啉胍同多十钒酸盐的自组装合成、结构表征及抗菌活性

通过十钒酸盐与吗啉胍在不同pH值水溶液中的自组装,合成了2个新化合物(C₆H₁₄N₅O)₄·[H₂V₁₀O₂₈]·9H₂O(1)和(C₆H₁₄N₅O)₆[V₁₀O₂₈]·4H₂O(2).通过IR,⁵¹VNMR和X射线衍射等方法对其结构进行了表征.结果表明,化合物1和2是通过十钒酸根阴离子与质子化的吗啉胍阳离子以静电力和氢键构筑的,多阴离子及吗啉胍的结构基本保持不变.抗菌试验结果表明,两种化合物对金黄色葡萄球菌、表皮葡萄球菌、耐甲氧西林金黄葡萄球菌和耐甲氧西林表皮葡萄球菌均具有较强的抑制活性.     

SELECTIVE ALTERATION OF THE PIGMENT COMPOSITION OF THE BLUE-GREEN ALGA, Anacystis nidulans

Abstract— Conditions were established which allow selective alteration of the pigment composition of Anacystis cells. Nitrate-starvation at 28°C and 39°C resulted in the preponderance of chlorophyll a (Chi a ) and that of phycocyanin (PC). In the case of starvation at 39°C strong correlation was observed between the disappearance of Chi a absorption and the appearance of an absorption band at 750 nm (P750) as the starvation proceeded. During regeneration the starved cells lost their P750 content. We show that P750 is quantitatively accounted for in the form of Chi a aggregates.     

Synthesis and Crystal Structure of Lanthanum Nitrate with Methyl－2－pyridyl Ketone Benzoyl Hydrazone

IntroductionThe coordination chemistry of Schiff base lig-ands has received more and more attention in thepast two decades[1— 4] .This kind of complexes pos-sesses a wide spectrum on biological and pharma-ceutical activities,such as antitumorand antioxida-tive activities[5,6] ,and studies on them are an inter-esting topic because of their electronic,magneticand photophysical properties[7] .Although a lot ofresearches have been reported,the studies con-cerned with the lanthanide complexes on t…     

配位聚合物{[Co2(HBTC)2(H2O)6]·C4H10N2·2H2O}n的水热合成、结构表征及荧光性质

采用水热法合成了配位聚合物[Co2(HBTC)2(H2O)6]·C4H10N2·2H2O}n(H3BTC为1,3,5-均苯三羧酸,C4H10N2为哌嗪),通过X射线单晶衍射、红外光谱和荧光光谱进行表征,并用TGA研究了该配位聚合物的热稳定性.晶体属三斜晶系,P1空间群,a=1.05437(9)nm,b=1.05485(9)nm,c=0.71482(5)nm,α=102.4623(28)°,β=91.3500(42)°,γ=111.0186(29)°,V=0.72018(10)nm3,Mr=764.37,Dc=1.762g·cm-3,Z=1,μ(MoKα)=1.25mm-1,F(000)=394,R=0.0307,wR=0.0815.晶体的基本构建单元中包含2个Co()中心、2个配位的HBTC分子和6个配位的水分子.基本构建单元通过相互链接形成具有“Z”型结构的一维配位聚合链,链间通过两种不同的氢键(O—H…O和N—H…O)相互作用,进而形成具有三维骨架结构的微孔晶体,微孔大小为0.71nm×0.82nm.荧光光谱表明,常温下用λex=312nm的光激发后,配位聚合物在329nm处出现强烈的荧光发射.     

稀土配合物{La［o-C6H4(NO2)(CO2)］3·(DMF)2}2的晶体结构及其荧光性能

合成了一种新的双核倒反中心的稀土镧配合物{La［o-C6H4(NO2)(CO2)］3·(DMF)2}2. 通过元素分析、 核磁共振谱和红外光谱对配合物的组成和结构进行了表征,  用热重分析研究了该配合物的热稳定性,  用X射线单晶衍射法测定了其晶体结构. 镧配合物{La［o-C6H4(NO2)(CO2)］3·(DMF)2}2晶体属三斜晶系, 空间群P1,  晶胞参数a=1.902(2) nm, b=1.245 0(2) nm, c=1.298 7(2) nm, α=64.555(2)°, β=66.348(2)°, γ=71.920(2)°, V=1.569 5(5) nm3, Dc=1.658 Mg/m3, Z=2, μ=1.437 mm-1, F(000)=784. 配合物中有2个La(Ⅲ)被4个邻硝基苯甲酸的羧酸根的负氧离子桥联, 每个La(Ⅲ)的中心离子配位数为9,  配位原子分别来自于7个邻硝基苯甲酸的羧酸根的负氧离子和2个DMF的羰基氧原子. 化合物中的氢键和π…π堆积作用使其成为三维立体结构. 同时发现了标题化合物固体具有光致发光现象, 发光性能测试表明， 配合物具有很好的荧光性质.     

(C6H8N3)+I3-和[(Cu3I4)(C8H17N2)]配体原位合成与结构表征

在溶剂热条件下, 以原位反应为基础合成了两个碘化物(C6H8N3)+I3-(1, C6H8N3=2,3-dihydroimi-dazo[1,2-a]pyrimidin-1-ium, 2,3-二氢咪唑[1,2-α]-嘧啶鎓阳离子)和[(Cu3I4)(C8H17N2)](2, C8H17N2=N-ethyl-4-aza-1-azonia-bicyclo[2.2.2]octane, N-乙基三乙烯二铵阳离子). 用元素分析、粉末X射线衍射及单晶X射线衍射等对化合物进行了表征. 结果表明, 化合物1属于三斜晶系, P1空间群, a=0.74281(15) nm, b=0.84241(17) nm, c=0.9993(2) nm, α=82.02(3)°, β=83.30(3)°, γ=82.92(3)°, V=0.6114(2) nm3. 化合物2属于单斜晶系, P21/c空间群, a=0.68924(14) nm, b=1.0786(2) nm, c=2.2779(5) nm, β=94.84(3)°, V=1.6874(6) nm3. 在两个化合物合成中存在两种不同类型的配体原位合成反应, 即化合物1的2-氨基嘧啶和乙醇的成环反应与化合物2的三乙烯二胺和乙醇的烷基化反应.     

发光配合物1,2-二(2-吡啶甲酰胺基)苯锌的研究

合成了发光配合物1,2-二(2-吡啶甲酰胺基)苯锌(1)及其双分子-4,4'-联吡啶复合物(2).用X射线单晶衍射分析方法得到了配合物2的单晶结构.该晶体属三斜晶系,P1空间群,晶胞参数为a=0.96251(6)nm,b=1.50122(9)nm,c=1.64252(12)nm,α=106.958(2)°,β=105.362(3)°,γ=102.978(2)°,V=2.0685(2)nm³,Z=2,D_c=1.563g/cm³,F(000)=1000,R₁=0.0367,wR₂=0.0898.研究表明,晶体2由1个4,4'-联吡啶通过配位键连接2个化合物1分子构成.晶体2是由沿晶体学b和c轴方向的一维分子柱堆积而成.考察了配合物1的发光性质,配合物1可作为发光材料效率很高的电致发光器件制备.     

Energy Transfer between Flavin and Cytochrome c

Energy transfer between photoexcited flavin and cytochrome c has been investigated in order to estimate intermolecular forces between flavin and cytochrome c. The quenching of the fluorescence of flavin by cytochrome c excited at 372 nm was found to be much greater than that excited at 465 nm. This dependence of the quenching on the exciting wavelength is considered to be due to the “prerelaxational” fast energy transfer. From the analysis of the quenching of the fluorescence of FMN and lumiflavin by cytochrome c excited at 465 nm, it was concluded that 1) the quenching is mainly controlled by resonance energy transfer, and 2) the heterogeneous dispersion state of molecules due to electrostatic forces makes the critical transfer distance, R ₀, of the resonance process longer than the real distance. For the quenching of the fluorescence of flavodoxin by cytochrome c, it was found that complex formation is a dominant process and is controlled to a great extent by electrostatic forces. Furthermore, fluorescence decay curves were measured by a single-photon counting method in order to estimate the dynamic processes of flavin fluorescence. The results also showed that the resonance process exists in the energy transfer between flavin and cytochrome c.     

THE SUBSTRATE-DEPENDENT PHOTOINACTIVATION OF UROCANASE FROM RAT LIVER

Abstract— Rat liver urocanase was readily inactivated by near-UV light in the presence of the substrate. Irradiation of substrate or enzyme alone was ineffective. The purpose of this study was to examine the conditions which influenced this inactivation and to investigate the mechanism. The urocanate concentration needed for 50% of the maximum inactivation for a 15 min irradiation was 0.09 μ M . Temperatures from 0 to 30°C during irradiation had little influence. Inactivation occurred at -75°C, which indicated a photochemical reaction. The pH had little influence on inactivation. Photoinactivation was the same in nitrogen and air. Dialysis experiments showed that unbound small molecules were probably not involved. Inactivated enzyme did not inhibit active enzyme. Chelators, reducing agents, and pyridoxal phosphate did not affect the inactivation. Visible light was not effective. An action spectrum was established with the aid of a monochromator. The action spectrum had a peak at 280 nm and a shoulder extending from 300 to 340 nm which rules out flavins. pyridoxal phosphate, a simple protein, and free urocanate as the chromophore. The results suggest that this photochemical process is not photodynamic action. It appears that only substrate and enzyme are needed for this photoinactivation. The enzyme-substrate complex may be the chromophore.     

七配位二聚体配合物{(PhCH2)2Sn·[2,6-(O2C)2C5H3N](CH3OH)}2的合成及结构

在三乙胺存在下利用三苄基氯化锡和2,6-吡啶二甲酸,以1:1摩尔比反应,合成了七配位二聚体{(PhCH2)2Sn[2,6-(O2C)2C5H3N](CH3OH)}2.通过元素分析、红外光谱和核磁共振氢谱对其结构进行了表征.用X射线单晶衍射法测定了该化合物的晶体结构.化合物为三斜晶系,P1空间群,晶胞参数a=0.9625(6)nm,b=1.0947(9)nm,c=1.996(3)nm,α=90.00(2)°,β=87.69(3)°,γ=90.00(3)°,Z=2,V=2.102(6)nm3,μ=1.248mm-1,F(000)=1000,R1=0.0476,wR2=0.0782.化合物中2个锡原子呈七配位畸变五角双锥构型.生物活性测试结果表明,该化合物具有较强的体外抗肿瘤活性.     

三环己基锡8-羟基喹啉配合物的微波辅助合成、结构表征、热稳定性和体外抗癌活性

微波辐射下,8-羟基喹啉与三环己基氢氧化锡反应,合成了三环己基锡配合物Cy3SnOC9NH6(Cy为环己基)。 通过UV、IR、1H和13C NMR、元素分析及X射线单晶衍射等技术手段表征结构。 实验结果表明,该配合物属三斜晶系,空间群P1,晶体学参数:a=0.99530(5) nm,b=1.01129(5) nm,c=2.58327(13) nm,α=89.1880(10)°,β=86.6290(10)°,γ=81.2490(10)°,Z=4,V=2.5654(2) nm3,Dc=1.326 Mg/m3,μ(MoKα)=1.013 mm-1,F(000)=1064,R1=0.0447,wR2=0.0891。 配合物在200 ℃以下稳定,对人体的癌细胞Colo205、HepG2、MCF-7和NCI-H460增殖均有较强的抑制作用。     

ENERGY TRANSFER VIA PROTEIN-PROTEIN INTERACTION IN RENILLA BIOLUMINESCENCE

Abstract—Radiationless energy transfer is known to play biologically important roles in both photosynthesis and bioluminescence. In photosynthesis, accessory pigments serve as "antennae", transferring excitation energy into the "reaction centers". In the bioluminescent coelenterates, energy is transferred from the site of reaction via an accessory protein known as the green-fluorescent protein (GFP). Coelenterate bioluminescence systems such as that of the sea pansy, Renilla , are well characterized biochemically, and their energy transfer process can be duplicated in vitro using isolated and purified components. We have measured efficient in vitro energy transfer from the electronic excited state of the enzyme-bound oxyluciferin to the green-fluorescent protein at protein concentrations of 0.1 μ M . We have also demonstrated a 1:l complex between these proteins, under conditions of energy transfer, by the chromato-graphic technique of Hummel and Dreyer. These observations indicate that bioluminescent energy transfer is mediated via protein-protein interaction. Furthermore, with inter-species cross-reaction studies and protein modification techniques we have shown that the interaction between luciferase and GFP is highly specific. These features make the Renilla system an attractive alternative to the photosynthetic systems as a tool for studying radiationless energy transfer.     

过氧钒配合物的合成、结构及模拟过氧化酶催化溴化动力学

根据模拟钒卤代过氧化物酶(V-HPOs)活性中心的配位环境,设计并合成了2种新型过氧钒配合物：Na[VO(O2)2(C10H8N2)]·8H2O(1)和K3H[(VO)2(O2)4(μ2-O)]·H2O(2),通过元素分析、红外光谱和紫外光谱对其进行了表征,并通过X射线单晶衍射方法确定了其结构。 配合物1晶体属于三斜晶系,空间群：P-1,a=0.7213(2) nm,b=1.1269(4) nm,c=1.3728(4) nm,α=68.349(4)°,β=89.178(4)°,γ=88.050(4)°,V=1.0365(6) nm3。 配合物2的晶体属于单斜晶系,空间群：P21/c,a=0.67047(12) nm,b=0.99503(18) nm,c=1.5817(3) nm,α=γ=90°,β=93.739(2)°,V=1.0530(3) nm3。 配合物1和2分别是五角双锥和八面体配位构型。 通过催化溴化反应活性研究发现,2种配合物均可作为潜在的钒卤代过氧化物酶模拟物。     

新型混价铜配合物[CuⅠCuⅡ(Ophen)2Cl]·H2O(HOphen=2-羟基-1,10-邻菲咯啉)的水热合成和晶体结构

报道了一种新型混价铜配合物[CuⅠCuⅡ(Ophen)2Cl]·H2O(HOphen=2-羟基-1,10′-邻菲咯啉)的水热合成和晶体结构.该化合物属于三斜晶系,P1空间群,a=0.91667(18)nm,b=1.0546(2)nm,c=1.1705(2)nm,α=80.50(3)°,β=80.56(3)°,γ=66.87(3)°,V=1.0202(3)nm3,Z=2,Dc=1.872Mg/m3,R1=0.0508,(wR2)=0.1481.标题化合物由一种新型的双核铜配合物和一个结晶水组成.邻菲咯啉在水热反应中发生羟基化,形成新型的羟基化邻菲咯啉.两个这样的配合物通过Cu…Cu间的范德华力相互作用形成二聚体.二聚体之间通过Ophen基团的π-π堆积以及C—H…Cl弱相互作用构筑成三维超分子网络.水分子处于网络的孔穴中.该化合物为邻菲咯啉的羟基化提供又一个新的范例.     

两个含N-皮考林酰肼铁配合物的合成和结构表征

合成了含N-乙酰皮考林酰肼(简写为Haphz)的铁配合物[Fe₂(aphz)₂(μ-CH₃O)₂Cl₂]·CH₃OH(1,C₁₉H₂₆Cl₂Fe₂N₆O₇,Mr=633.06)和含N-苯甲酰皮考林酰肼(简写为Hphphz)的铁配合物Fe(phphz)Cl₂(2,C₁₃H₁₀Cl₂FeN₃O₂,Mr=366.99).2个配合物均属三斜晶系,空间群为P     

MEASUREMENT OF DNA CROSSLINKS BY S1 NUCLEASE: INDUCTION AND REPAIR IN PSORALEN-PLUS-360 nm LIGHT TREATED ESCHERICHIA COLI

Abstract—DNA crosslinks in Escherichia coli cells. exposed to 4.5',8-trimethylpsoralen plus 360 nm light, were measured using a rapid and sensitive new approach. The assay is based on the specificity of S₁ nuclease from Aspergillus oryzae to single-stranded DNA. Bacterial cells were lysed and the DNA denatured by alkali. Following acid neutralization. crosslinked DNA undergoes spontaneous renaturation and is rendered S₁-nuclease resistant and therefore acid-precipitable. The single-stranded fraction after denaturation by alkali decreases with increasing near UV light exposure in the presence of TMP following first order kinetics. The kinetics were faster when exposure was at 4°C rather than at 20°C. This suggests that excision of crosslinks occurs during exposure at the higher temperature. Indeed. since the rate of DNA crosslinking in a uvr B mutant which is excision-deficient was higher than in wild type bacteria at 4°C, some excision must have occurred even in the cold. DNA from excision-proficient cells incubated at 37°C following exposure to TMP-plus-near UV at 4° showed a greater single stranded fraction than that from non-incubated cells. This indicates repair of DNA crosslinks. which proceeded with a half-time of 8 min at 37°C and was unaffected by substitution of thymine in DNA by 5-bromouracil.     

二水合L－精氨酸顺丁烯二酸加合物的制备和晶体结构

制备了具有非线性特性的标题化合物,以降温法培养出25mm×40mm×13mm大尺寸单晶,该单晶在1064nm的Nd³⁺:YAG激光束照射下,产生绿色的532nm倍频光,以X射线衍射法测定了此1:1:2加合物的晶体结构,晶体属P₁空间群,a=0.5269(1)nm,b=0.8040(1)nm,c=0.9783(2)nm,α=106.14(1)°,β=97.27(1)°,γ=101.64(1)°,Z=1,R=0.062.L-精氨酸与顺丁烯二酸之间以氢键相联,形成三维氢键网络。