对苯二胺和N-取代衍生物正离子自由基的共振喇曼光谱研究

本文中报道了对苯二胺和四种N-烷基取代衍生物正离子自由基的共振喇曼光谱, 揭示了自由基是具有明显C=C和C=N双键性质的半醌式结构, N原子上给电子基团的取代引起上述化学键振动峰低频移动, 反映出结构一端N上有烷基的自由基中与取代基直接相连的N原子失去一个p电子带正电荷, 并吸引环上的π电子形成一定程度C=N双键. 共振喇曼光谱随激发光波长的变化表明, 自由基的两个可见电子吸收带分别主要产生于环结构的π→π*和包含N原子结构的n→π*电子跃迁。     

人工神经网络在喇曼光谱数据处理中的应用

将人工神经网络（ａｒｔｉｆｉｃｉａｌｎｅｕｒａｌｎｅｔｗｏｒｋｓ）应用于喇曼光谱数据处理中。研究了学习时间常数μ（ｌｅａｒｎｉｎｇｒａｔｅｃｏｅｆｆｉｃｉｅｎｔｓ）及传递函数（ｔｒａｎｓｆｅｒｆｕｎｃｔｉｏｎｓ）对网络性能的影响，发现当μ＝０．５时，网络运行最佳。通过比较原始谱图及经网络处理后所得谱图，证明采用带有Ｓ形传递函数的前向网络能获得较好的信噪比，谱线的分辨率也有所提高。     

温度对光学纤维自发喇曼光谱强度的影响

测量了不同温度下ＣＣｌ４液芯光纤喇曼光谱强度，实验结果表明，光谱强度随着温度的变化存在着一个极大值，对影响光纤喇曼光谱强度的几个主要因素进行了估算，理论与实验结果符合较好。     

激光喇曼光谱法测定MoO_3在载体表面的单层分散容量

用激光喇曼光谱法测定了MoO_3/γ-Al_2O_3、MoO_3/TiO_2和MoO_3/SiO_2中聚集态MoO_3量和负载量的关系。外推得出的单层分散容量与从XRD、XPS及表面酸性测定中得出的结果相符,因而为MoO_3在载体表面单层分散的观点提供了直接的证据。从LRS谱中还得出一些XPS、XRD未能得出的结构信息。对LRS定量中遇到的一些问题、起因及解决办法也进行了讨论。     

血红蛋白在银溶胶上的表面增强喇曼光谱研究

表面增强喇曼光谱已广泛应用于物质分子在金属表面吸附的研究.人们发现,不仅无机物和有机小分子能产生SERS,而且生物分子,如核酸、色蛋白以及蛋白质均能产生SERS效应,并以此来研究生物分子-蛋白质的变性问题.     

荧光素钠互变异构体的表面增强共振喇曼散射光谱

本文报导了不同pH值下荧光素钠吸附于银岛膜的表面增强共振喇曼散射(SERRS)光谱。由于在不同pH值的溶液中荧光素钠具有不同的离子构型, 其SERRS光谱也有所不同, 其差异主要表现在谱线强度的变化而不是频率变化。谱线强度随pH值的变化形式可分为两种类型, 这与其相对应的振动模的性质有关。利用“四级能模型”和共振喇曼理论对实验结果进行了分析。     

吩噻嗪和吩噁嗪氧化中间体的共振喇曼光谱研究

本文对吩噻嗪和吩噁嗪的单电子氧化产生的两种氧化态的亚稳态正离子进行了共振喇曼光谱研究。随着吩噻嗪的p电子逐步失去,结构变形振动δ_(CNC)和δ_(CSC)的喇曼频移显著地增大,环C=C伸缩振动区域的喇曼峰数目明显变多。由此推断,随着吩噻嗪正离子氧化态的增高,正离子转变成平面共轭结构。     

反向泵浦的受激喇曼光声光谱

An improved experiment setup for Stimulated Photoacoustic Raman Spectroscopy（PARS）was reported. The employed two laser beams,unlike general arrangement of propagating in the same direction,counterpropagated with each other. This arrangement can eliminate the limitation that the small Raman shift could not be measured with general arrangement. Therefore,this improved setup was especially useful for measuring the PARS spectrum with small Raman shift,such as the pure rotational Raman spectrum. In the experiment,taking CH4 molecules as a research object,one laser was fixed at 532. 1 nm while another tunable dye laser scanned. The PARS spectrum of CH4 molecules for the v1 ,v2 and v3 bands was recorded in the two wavelength ranges of 625-642 nm and 573-589 nm,and the results agreed well with those obtained by Spontaneous Raman Scattering（ORS）technique,confirming the validity of the improved experimental setup.     

钌联吡啶络合物与脱氧核糖核酸分子相互作用的荧光光谱研究与分析应用

合成了2苯基(4溴)咪唑[f]邻菲咯啉(简称PIP(Ⅲ)新的配体及〔Ru(bpy)_2PIP(Ⅲ)]~(2+)新的络合物,用荧光光谱研究了络合物与小牛胸腺DNA分子的结合情况,在 pH7.4,络合物与DNA作用后,在587nm(λ_(ex)=471nm)产生很强的荧光峰,其发光强度与DNA浓度呈线性关系;线性范围0～1.2mg/L;检测限(3a(?))为2.8mg/L.该方法具有较高灵敏度和准确度,对合成样品测定,结果令人满意.     

Luminescence Studies on Interaction of an Isoquinoline Alkaloid with Calf Thymus DNA in Aqueous Medium and on Solid Substrate

The interaction of calf thymus DNA(ctDNA) with berberine(Ber) was systematically investigated via UV-Vis, fluorescence and phosphorescence spectroscopies in aqueous solution and on solid substrate. The very weak fluorescence intensity of Ber at 525 nm in aqueous solution can be greatly enhanced by ctDNA. The UV-Vis spectrum shows that Ber could bind with DNA by intercalation. In addition, strong fluorescence of Ber alone could be observed on filter paper substrate and can be quenched by ctDNA effectively, and the increase of fluorescence polarization of Ber on the filter paper implies the intercalation binding. Ber emits phosphorescence at 619 nm in the presence of thallium(I) acetate. The lifetime of Ber increased from 38.4 ms to 43.4 ms with the increase of ctDNA. The increase of lifetime is possibly attributed to the increase of rigidity of Ber after its intercalating into the ctDNA base pairs. This explanation is also augmented by the anionic quenching results. Ber behaves as a typical intercalating agent into ctDNA.The intrinsic binding constant between Ber and ctDNA is (1.84?0.12)?10⁴ L/mol and n=0.16.     

钌卟啉[Ru(bpy)2(MPyTPP)Cl]+与DNA作用的研究

钌卟啉(ruthenated porphyrin)是通过卟啉环上的配位基团与多吡啶钌配位而得到的一类具有丰富的光谱和化学活性的大分子配合物[1～5]. 目前, 对钌卟啉的研究大都集中在其氧化还原、电化学以及催化氧化反应活性和超分子自组装等方面, 而对钌卟啉生物功能方面的研究则鲜为报道[6].     

农药异丙威与小牛胸腺DNA的作用研究

在生理酸度条件下,采用紫外光谱和荧光光谱法研究异丙威与小牛胸腺DNA的作用表明:DNA对异丙威的荧光有明显的猝灭作用,属于静态猝灭方式;K4[Fe(CN)6]猝灭试验发现DNA对异丙威有明显的保护作用,离子强度的改变对异丙威和异丙威-DNA体系的荧光均无明显影响;异丙威的加入使DNA的熔点升高,并且异丙威能够竞争置换EB与DNA的结合位点。上述实验也表明,异丙威以嵌插方式作用于DNA的结合位点,有可能通过形成DNA加合物的形式造成DNA损伤,从而最终导致基因突变。     

Improved Fluorometric DNA Determination Based on the Interaction of the DNA/Polycation Complex with Hoechst 33258

When DNA is mixed with the cationic polyelectrolyte poly(diallyldimethyl ammonium chloride) (PDDA), the DNA/PDDA complex is formed instantaneously at room temperature. This complex is much more efficient in enhancing the fluorescence of Hoechst 33258 (H 33258) than DNA alone. Based on the interaction of H 33258 with the DNA/PDDA complex, a new fluorescence assay for DNA is described. At pH 7.3 in Tris-HCl buffered solution, the DNA/PDDA complex causes a sharp enhancement in fluorescence intensity of H 33258. Simultanously, the emission maximum wavelength of H 33258 blueshifts from 490nm to 450nm, while the excitation redshifts from 345 to 350nm. The calibration graphs for calf thymus DNA (ctDNA) and herring sperm DNA (hsDNA) are both linear up to 5.0µgmL^–1 when the concentration of H 33258 and PDDA are fixed at 1.5×10^–6 and 1.6×10^–5molL^–1, respectively. The method is specific for native DNA. The 3 detection limits for ctDNA and hsDNA are 1.8 and 5.6ngmL^–1, respectively, i.e. much lower than in the presence of H 33258 alone. Four synthetic samples were determined satisfactorily. This method can also be developed to investigate the formation and the nature of the complexes between DNA and polycations, which have recently been widely applied in some fields such as genetic engineering and gene therapy.     

红景天苷与DNA的结合作用研究

在pH=7.4的生理酸度条件下,采用荧光光谱和紫外-可见光谱法,并结合I-效应、离子强度的影响、DNA熔点及粘度测定等实验手段,研究了红景天苷与小牛胸腺DNA的相互作用.结果表明,DNA对红景天苷的内源荧光有明显的猝灭作用,猝灭过程为静态猝灭.由荧光猝灭实验数据,计算出不同温度下红景天苷与DNA之间作用的结合常数和热力...     

不同波段的紫外辐射对DNA构象影响的拉曼光谱研究

研究了小牛胸腺DNA水溶液经不同时问不同波段紫外辐射后的拉曼光谱。结果表明：仅仅经过9min强度为18．68W／m^2。的全波段紫外辐射,DNA就遭到了严重损伤：表征PO2^-对称伸张振动的1094cm^-1谱线分裂成4条谱线．说明DNA构象遭到破坏,构型发生了变化。UV—A＆UV—B波段的紫外辐射对DNA的影响比全波段的紫外辐射对DNA的影响小得多,但经过较长时间辐射后,仍对DNA构型构象产生了影响,即A型构象增强,B型构象减弱．经过2h的UV—A辐射,出现了表征A型构象的805cm^-1和816cm^-1谱线,且816cm^-1峰与未经辐射的表征A型的803cm^-1峰相比,强度大得多。经过16h的UV—A辐射后,805cm^-1谱线消失,816cm^-1谱线移到了813cm^-1,且强度减弱50％,表明水溶液中的DNA在UV—A照射中A型构象不稳定,处于变化之中。     

A study on the binding of two water-soluble tetrapyridinoporphyrazinato copper(II) complexes to DNA

Interaction of N,N′,N″,N-tetramethyltetra-2,3-pyridinoporphyrazinatocopper(II), ([Cu(2,3-tmtppa)]⁴⁺) and N,N′,N″,N-tetramethyltetra-3,4-pyridinoporphyrazinatocopper(II), ([Cu(3,4-tmtppa)]⁴⁺) with calf thymus DNA was studied in 1 mM phosphate buffer and low ionic strength (5 mM NaCl) at various temperatures by UV-visible and circular dichroism (CD) spectroscopies and viscometric method. The binding constants were determined from the changes in the visible part of porphyrazine complexes spectra using SQUAD software. The values of K have been obtained (7.9±0.4)×10⁴ and (2.2±0.1)×10⁵ M⁻¹ for [Cu(2,3-tmtppa)]⁴⁺ and [Cu(3,4-tmtppa)]⁴⁺, respectively at 27 °C. The higher affinity of 3,4-isomer of Cu complex towards DNA with respect to the 2,3-isomer was attributed to favorable external positioning of the cationic charges in former, which enables superior interaction with the DNA duplex. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were calculated by van't Hoff equation. The enthalpy and entropy changes were determined, +34.2±3.6 kJ mol⁻¹ and +207.8±12.70 J mol⁻¹ K⁻¹ for [Cu(2,3-tmtppa)]⁴⁺ and +49.7±2.1 kJ mol⁻¹ and +267.8±7.9 J mol⁻¹ K⁻¹ for [Cu(3,4-tmtppa)]⁴⁺. The existence of extensive hypochromicity, large red shift and negative CD in the visible part of [Cu(3,4-tmtppa)]⁴⁺ spectra suggested an intercalation binding mode. Analysis of the moderate hypochromicity, red shift and bisignate CD in the Q-band absorption region of [Cu(2,3-tmtppa)]⁴⁺ spectra possibly led us to the coexistence of intercalation and outside binding modes. The influence of the ionic strength on the binding parameters and binding modes was investigated. The results show that increase in ionic strength causes the decrease in the binding constants. It was also concluded that increase in ionic strength affects the binding characteristics of positively charged complexes with DNA.

The increase in DNA viscosity in the presence of Cu–tmtppa complexes is attributed to the lengthening of DNA helix due to the intercalation. This result is consistent with conclusions obtained from the spectroscopic techniques.     

Quinoidal/Aromatic Transformations in π‐Conjugated Oligomers: Vibrational Raman studies on the Limits of Rupture for π‐Bonds

The vibrational Raman spectra of several series of aromatic and quinoidal compounds have been analyzed considering the downshifts and upshifts of the frequencies of the relevant Raman bands as a function of the number of repeating units. Oligothiophenes, oligophenylene‐vinylenes, and oligoperylenes (oligophenyls) derivatives are studied in a common context. These shifts are taken as spectroscopic fingerprints of the changes in π‐conjugation. For a given family, aromatic and quinoidal oligomers have been studied together, and according to their Raman frequency shifts located in the two‐well BLA–energy curve of their ground electronic state as a function of the bond‐length‐alternation pattern (BLA). The connection among BLA values, π‐conjugation, and Raman frequencies is taken here as the basis of the study. These Raman shifts/BLA changes have been related to important electronic properties of these one‐dimensional linear π‐electron delocalized systems such as quinoidal (polyene) and aromatic characters.     

X-ray crystal structure of a Cu(II) complex with the antiparasitic drug tinidazole,interaction with calf thymus DNA and evidence for antibacterial activity

Interaction of metal ions with biologically active molecules like 5-nitroimidazoles modulates their electronic environment and therefore influences their biological function. In the present work, an antiparasitic drug tinidazole (tnz) was selected and a Cu(II) complex of tnz [Cu₂(OAc)₄(tnz)₂] was prepared. A dinuclear paddle-wheel [Cu₂(OAc)₄(tnz)₂] was obtained by single-crystal XRD and further characterized by spectroscopic techniques and cyclic voltammetry. To understand the biological implications of complex formation, interaction of tnz and its complex was studied with calf thymus DNA, bacterial and fungal cell lines. Results of calf thymus DNA interaction using cyclic voltammetry indicate the overall binding constant (K^*) of Cu₂(OAc)₄(tnz)₂ [(59?±?6)?×?10⁴?M^?1] is ~17 times greater than that of tnz [(3.3?±?0.4)?×?10⁴?M^?1]. Minimum inhibitory concentration values suggest that [Cu₂(OAc)₄(tnz)₂] possesses better antibacterial activity than tnz on both bacterial strains, while the activity on a fungal strain was comparable.     

Electrochemical Sensor Based on Oxidation of 2,8‐Dihydroxyadenine to Monitor DNA Damage in Calf Thymus DNA

A novel and reliable direct electrochemical method has been established to monitor DNA damage in acid hydrolyzed calf thymus DNA, based on the determination of 2,8‐dihydroxyadenine (2,8‐DHA). A single‐wall carbon nanotubes (SWCNT) modified edge plane pyrolytic graphite electrode (EPPGE) has been used as a sensor to monitor the DNA damage. 2,8‐DHA the main in vivo adenine oxidation product undergoes oxidation at ～395 mV at SWCNT modified EPPGE using square wave voltammetry (SWV). The sensor exhibits potent and persistent electron‐mediating behavior. A well‐defined oxidation peak for the oxidation of 2,8‐DHA was observed at modified electrode with lowering of peak potential and increase in peak current as compared to bare EPPGE. At optimal experimental conditions, the catalytic oxidative peak current was responsive with the 2,8‐DHA concentrations ranging from 0.05 nM to 100 nM. The detection limit was 3.8×10^?11 M and limit of quantification was 1.27×10^?10 M. The modified electrode exhibited high stability and reproducibility.