光谱法研究硝基苯基卟啉锌与咪唑类的轴向配位反应

采用紫外-可见光谱滴定法和荧光光谱法,考察了5-对硝基苯基-10,15,20-三苯基锌卟啉和5-邻硝基苯基-10,15,20-三苯基锌卟啉与3种咪唑类客体小分子进行轴向配位反应的光谱性质,并探讨取代基团在不同位置时的锌卟啉及具有不同结构特点的客体对该类轴配反应进行的影响。 实验结果表明,2种锌卟啉与咪唑类客体之间的轴配反应是按摩尔比1∶1进行,轴配反应的平衡常数均按K(2-MeIm)＞K(N-MeIm)＞K(Im)顺序依次减弱,其中5-邻硝基苯基-10,15,20-三苯基锌卟啉与2-甲基咪唑间的轴配反应有最大的平衡常数5.85×10⁵ L/mol。 轴配反应的平衡常数均随温度的升高而降低,温度升高不利于平衡反应的进行。 热力学参数表明,这类反应的驱动力是焓驱动,是自发进行的配位反应。 随客体浓度的增加,5-对硝基苯基-10,15,20-三苯基锌卟啉(荧光峰位：592.9、634.2 nm)与咪唑类客体的轴配体系具有荧光增强的效应,5-邻硝基苯基-10,15,20-三苯基锌卟啉(荧光峰位：583.6、629.8 nm)与咪唑类客体的轴配体系具有荧光猝灭的效应。 轴配体系的荧光效应是由锌卟啉中硝基基团的位置所决定的,而与客体的结构特点无关。     

碘化四(4-三甲胺苯基)卟啉铁(II)配合物的聚合及其轴向配位的研究

本文通过元素分析、磁化率、红外光谱、紫外可见光谱进一步确定了碘化四(4-三甲胺苯基)卟啉铁(III)配合物的组成和结构. PH滴定曲线证明它在不同PH水溶液中存在单体和二聚体平衡. 通过PH光度法求出在恒定离子强度下(μ=0.1FNaNO3)聚合物的聚合度、聚合平衡常数及其热力学参数. 用分光光度法测定了该二聚体与生物轴向配体(咪唑、1-甲咪唑、L-组氨酸及吡啶)反应平衡常数及热力学参数, 其配位能力大小顺序为:咪唑>1-甲基咪唑>L-组氨酸>吡啶. 还求出上述反应在水-二氧六圜混合溶剂中的平衡常数, 得出lgK与1/8呈线性关系(8为介电常数), 并对热力学参数进行了讨论.     

碘化四(4-三甲胺苯基)卟啉铁(Ⅲ)配合物的聚合及其轴向配位的研究

本文通过元素分析、磁化率、红外光谱、紫外可见光谱进一步确定了碘化四(4-三甲胺苯基)卟啉铁(Ⅲ)配合物的组成和结构。pH滴定曲线证明它在不同pH水溶液中存在单体和二聚体平衡。通过pH光度法求出在恒定离子强度下(μ=0.1FNaNO_3)聚合物的聚合度、聚合平衡常数及其热力学参数。用分光光度法测定了该二聚体与生物轴向配体(咪唑、1-甲基咪唑、L-组氨酸及吡啶)反应平衡常数及热力学参数,其配位能力大小顺序为:咪唑>1-甲基咪唑>L-组氨酸>吡啶。还求出上述反应在水-二氧六圜混合溶剂中的平衡常数,得lgK与1/ε呈线性关系(ε为介电常数),并对热力学参数进行了讨论。     

碘化四(4-三甲胺苯基)卟啉铁(II)配合物的聚合及其轴向配位的研究

本文通过元素分析、磁化率、红外光谱、紫外可见光谱进一步确定了碘化四(4-三甲胺苯基)卟啉铁(III)配合物的组成和结构. PH滴定曲线证明它在不同PH水溶液中存在单体和二聚体平衡. 通过PH光度法求出在恒定离子强度下(μ=0.1FNaNO3)聚合物的聚合度、聚合平衡常数及其热力学参数. 用分光光度法测定了该二聚体与生物轴向配体(咪唑、1-甲咪唑、L-组氨酸及吡啶)反应平衡常数及热力学参数, 其配位能力大小顺序为:咪唑>1-甲基咪唑>L-组氨酸>吡啶. 还求出上述反应在水-二氧六圜混合溶剂中的平衡常数, 得出lgK与1/8呈线性关系(8为介电常数), 并对热力学参数进行了讨论.     

新型Salen型配合物的合成和表征及轴向配位热力学

采用金属模板法合成了四个新型Salen型单、双核金属配合物,并用元素分析、核磁共振(1HNMR)、电喷雾质谱(ESI-MS)、傅里叶变换红外光谱(FT-IR)等手段进行了表征.使用紫外-可见(UV-Vis)光谱滴定法和圆二色(CD)光谱研究了主体金属镍配合物与咪唑类含氮小分子的轴向配位反应热力学性质.结果表明:主体与咪唑(Im)和N-甲基咪唑(N-MeIm)的配位数是2,而与2-Et-4-MeIm和2-MeIm的配位数是1;轴配体系的热力学数据显示主体与咪唑类配体的平衡常数按K苓(Im)K苓(N-MeIm)K苓(2-Et-4-MeIm)K苓(2-MeIm)顺序依次减小;测得的△rHm苓和△rSm苓数据表明该轴向配位反应为放热、熵增加过程.     

不同类型表面活性剂与高铁肌红蛋白相互作用

通过UV-Vis吸收光谱、同步荧光光谱、圆二色(CD)光谱等方法对阴离子型表面活性剂——琥珀酸二辛酯磺酸钠(AOT)和十二烷基苯磺酸钠(SDBS)、阳离子型表面活性剂——十六烷基三甲基溴化铵(CTAB)和十二烷基三甲基溴化铵(DTAB)、两性离子型表面活性剂——3-[(3-胆固醇氨丙基)二甲基氨基]-1-丙磺酸(CHAPS)与马心高铁肌红蛋白(metMb)的不同作用机理进行了探讨.结果显示:阴、阳离子型表面活性剂可以与蛋白发生较强烈的作用,且相互作用与表面活性剂的浓度密切相关.AOT和SDBS浓度的升高使得metMb的Soret带发生红移且出现两个新的Q带,伴随着配体金属电荷转移(LMCT)带的消失,蛋白从水合的六配位高自旋复合物(6-cHs)转化成六配位低自旋高铁血红素复合物(6-cLs),低浓度的AOT和SDBS对Tyr和Trp微环境均有影响,能使metMb的二级结构发生变化;而CTAB和DTAB在低浓度时对metMb的血红素中心影响不大,但是对Trp和Tyr的微环境影响很大,高浓度时主要通过静电吸引作用以聚合体形式直接作用于血红素中心,使Soret带发生蓝移,metMb形成五配位高自旋(5-cHs)复合物,血红素从疏水腔中释放出来,metMb的α螺旋含量减少.DTAB由于自身结构的特点,与CTAB作用于蛋白的过程有些区别,形成了一个中间态,但最终也导致血红素的暴露.两性离子型表面活性剂在测定浓度范围内不与metMb发生作用,原因是CHAPS整体呈电中性,其与metMb的阴离子性或者阳离子性位点作用的能力很弱,同时也说明metMb表面带相反电荷的位点相距较远.结果充分证明表面活性剂与蛋白相互作用的方式与表面活性剂的种类、结构及其浓度有关.     

超导核磁共振研究金属卟啉与配体交换动力学

用超导核磁共振研究了4种咪唑配体与金属卟啉铁(Ⅲ)和锰(Ⅲ)配位的交换反应动力学.探讨了不同轴向配体对同一金属卟啉、金属卟啉环上取代基、不同金属离子以及温度等因素对交换反应动力学的影响,进一步验证了线性热力学函数关系的存在.     

紫外光照下高铁肌红蛋白的还原

实验中我们发现紫外波段光源照射高铁肌红蛋白(metmyoglobin,metMb)时,能发生与添加化学还原剂还原metMb相似的过程,本文采用紫外可见吸收光谱(UV-Vis),圆二色光谱(CD)研究了metMb在特定紫外光源下的还原过程。580 nm和544 nm处还原峰的面积变化显示,metMb在光照时能被还原至MbFe髤H2O状态,且不同的光源、特定紫外定波长、温度、pH以及不同气体存在等条件下metMb的还原程度不同。在温度为10℃,偏碱性条件时,定波长254 nm照射有利于metMb还原;气体存在时,由于气体小分子与血红素铁的配位能力不同,不同气体对光照metMb还原的催化作用程度也有差异,CO和O2的存在对此过程有催化促进作用,这一结论在医学和生理学上有重要的意义。     

尾式锌卟啉轴向配位反应的光谱性质

采用紫外-可见光谱和荧光光谱滴定方法考察了5-p-(4-溴乙氧基)苯基-10,15,20-三苯基锌卟啉和5-p-(4-烟酸乙氧基)苯基-10,15,20-三苯基锌卟啉与咪唑类客体之间的配位反应性质。热力学实验研究结果表明,2种锌卟啉与咪唑类客体之间的轴配反应是按摩尔比1∶1进行的,轴配反应的平衡常数均按K(2-MeIm)>K(N-MeIm)>K(Im)的顺序依次减弱,其中5-p-(4-烟酸乙氧基)苯基-10,15,20-三苯基锌卟啉与2-甲基咪唑间的轴配反应有更大的平衡常数,为5.46×105L/mol。荧光光谱滴定实验显示,随客体浓度的增加,2种主体与咪唑类客体形成的轴配体系均具有荧光猝灭效应。     

羟基锌卟啉轴向配位反应的光谱性质研究

通过紫外-可见光谱滴定法,对2种羟基锌卟啉配合物与3种咪唑类客体小分子进行轴向配位反应的热力学性质进行了研究.同时,结合荧光光谱法考察了客体浓度对配位反应荧光性质的影响.实验结果表明:(1)咪唑类客体的轴向配位能力按2-MeIm>N-MeIm>Im的顺序依次减弱;(2)咪唑类客体与主体进行轴向配位反应时将产生荧光猝灭效应.     

Luminescent study on the binding interaction of bioactive imidazole with bovine serum albumin-A static quenching mechanism

Novel bioactive imidazole derivatives were synthesized and characterized by NMR spectra, mass and CHN analysis. The interaction between the imidazole derivative and bovine serum albumin (BSA) was investigated by fluorescence and UV-vis absorption spectroscopy. The fluorescence quenching of BSA by the imidazole derivatives may be due to the formation of imidazole-BSA complex. The fluorescence quenching mechanism of BSA by imidazole was analyzed and the binding constant has been calculated. The binding distance between imidazole and BSA was obtained based on Forester's non-radiation energy transfer (FRET). The effect of some common ions on the binding constant between imidazole and BSA was also examined.     

酞菁钴(Ⅱ)轴向配合物的合成及其光谱特性研究

本文合成了一种酞菁钴(Ⅱ)化合物,研究了它在溶液中与咪唑形成轴向配合物的吸收光谱变化,并计算了配合物的组成及稳定常数.用旋涂法制备了染料薄膜,通过配合物的吸收光谱与酞菁钴(Ⅱ)的比较,光谱峰显著变窄,吸收峰红移,大大改善了染料的光学性质.     

Synthesis of imidazole‐containing conjugated polymers bearing phenol unit as side group and excited state intramolecular proton transfer‐mediated fluorescence

Dibromobenzimidazole and dibromoimidazole bearing hydroxyl group‐protected phenol unit ( 1 and 2 ) were prepared and they showed an intramolecular hydrogen bonding between ether oxygen and amino proton of imidazole. The palladium‐catalyzed Suzuki coupling polymerization of 1 and 2 with benzene bis(boronic acid) derivatives gave soluble polymers ( 3 and 4 ), where the molecular weights were limited probably due to the coordination ability of imidazole to palladium metal. The phenol hydroxyl groups were subsequently deprotected using BBr₃ to obtain 3 ′ and 4 ′. From the ¹H NMR spectra, the complete conversion to the hydroxyl group and the formation of another type of intramolecular hydrogen bonding between hydroxyl proton and imine nitrogen were confirmed. In the UV and PL spectra of 3 ′ and 4 ′, the excited state intramolecular proton transfer (ESIPT) occurred to shift the emission spectra toward lower energy region compared to 3 and 4 . Especially, the PL spectrum of 3 ′ demonstrated large stokes shift (145 nm) in THF solution. The ESIPT‐mediated fluorescence was influenced by the addition of methanol and trifluoroacetic acid, which inhibited the formation of intramolecular hydrogen bonding. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4822–4829, 2009     

Raman spectroscopic and electrochemical characterization of myoglobin thin film: implication of the role of histidine 64 for fast heterogeneous electron transfer.

Myoglobin (Mb) thin films formed on various substrates have been characterized by using Raman spectroscopy, reflectance absorbance FT-IR, UV-vis absorption spectroscopy, and electrochemical methods. Raman spectra were obtained upon excitation within the Soret band as well as alpha-beta bands. The spin state marker bands observed from the Mb film in the 1550-1630 cm(-)(1) region (excitation at 514.5 nm) are approximately 20 cm(-)(1) higher than those of aqueous metMb having the high spin state. The 1210 cm(-)(1) band (methine bridge C-H vibration) also shifts to 1240 cm(-)(1) upon the formation of the film. These results indicate that the heme iron of myoglobin in the film is the ferric low-spin state, and the iron atom is pulled to the heme plane. A comparison of the Raman spectra of the Mb film with that of an Mb-imidazole derivative leads to the conclusion that the distal histidine is responsible for the change in the spectral characteristics. The escape of water from the sixth position upon the formation of the Mb film may result in a conformational change at the heme distal pocket: the histidine residue at the E7 helical position (H64) moves toward the central iron and is coordinated with it through the N on the imidazole ring. These structural features facilitate the fast electron transfer between the thin protein film and the electrode. Distal histidine may serve as an electron-transfer pathway as it does in cytochrome c.     

两个含1-(1-萘甲基)咪唑的化合物：晶体结构和弱相互作用

1-(1-萘甲基)咪唑(L)和盐酸反应生成1-(1-萘甲基)咪唑盐酸盐L·HCl (1),在这个化合物中通过π-π堆积相互作用和氢键形成了二维超分子层。1-(1-萘甲基)咪唑(L)和AgPF₆反应生成单核银配合物[L]₂AgPF₆ (2),在这个化合物中通过2个类型的π-π堆积相互作用形成了二维超分子层。测定了L,1和2的荧光发射光谱。     

Mechanistic investigation on binding interaction of bioactive imidazole with protein bovine serum albumin--a biophysical study

The interaction between bioactive imidazole derivative (PPP) and bovine serum albumin (BSA) was investigated using fluorescence and UV-vis spectral studies. The experimental results showed that the fluorescence quenching of BSA by imidazole derivative was the result of the formation of BSA-PPP complex and the effective quenching constants (K(SV)) were 2.66×10(4), 2.56×10(4), and 2.10×10(4) at 301, 310 and 318 K, respectively. Static quenching and non-radiative energy transfer were confirmed to the result in the fluorescence quenching. The binding site number n, apparent binding constant K(A) and corresponding thermodynamic parameters (ΔG, ΔH and ΔS) were measured at different temperatures. The process of binding of PPP molecule on BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased.     

Vibrational spectroscopic and density functional theory studies of chloranil-imidazole interaction

The present work reports vibrational spectra and density functional theory calculations for chloranil, imidazole and their complexes. The experimentally observed infrared and Raman bands have been assigned with the help of calculated vibrational frequencies and potential energy distribution analysis. Some bands of chloranil and imidazole have been found to shift on the complex formation due to partial electronic charge transfer from imidazole to chloranil. The charge transfer between these molecules is also corroborated by the electronic absorption spectroscopy and calculations. The theoretical values of the interaction energy of various possible chloranil-imidazole interactions suggest that the two molecules interact preferably via N and H atoms of imidazole and CO group of chloranil with their molecular planes almost perpendicular to each other.     

Carboxylic acid recognition of diamidine having a fluorescent 1,8-diphenylanthracene unit and its detection of amidinium-carboxylate and amidinium formation

A diphenylanthracene-based diamidine (1a) fluorescent probe for the detection of dicarboxylic acids has been designed and synthesized, which has an extended π-conjugation rather than a simple anthracene ring, in order to observe highly different fluorescence wavelengths after complex formation with dicarboxylic acids. The fluorescence spectra of the mixed solution of the diamidine 1a and carboxylic acids showed two different fluorescence bands, which corresponded to the complex formation (amidinium-carboxylate formation, λ_em?=?450?nm, light blue color) and dissociated amidinium formation (λ_em?=?510?nm as a broad band, green color). The complexed and dissociated states were confirmed by DOSY NMR and TD-DFT calculations. These different fluorescence wavelengths may come from the differences in the dihedral angles between the phenyl rings at the 1,8-position and anthracene ring (difference in π-conjugation) of 1a under complex formation and dissociated amidinium formation. The proposed mechanism for the observation of the different fluorescence wavelengths (complex formation and amidinium formation) was also confirmed by the fluorescence study of diamidine 1b which causes restricted rotation of the phenyl rings by substitution of the steric methyl groups, and observed the same fluorescence spectra for the complex formation and amidinium formation (400, 420, 450?nm as a vibrational structure of anthracene ring). These fluorescence characteristics of the diamidine 1a are also applicable for the detection of α,ω?dicarboxylic acids.     

阿魏酸哌嗪与牛血清白蛋白相互作用的研究

在模拟人体生理条件下,用常规荧光光谱法和紫外-可见吸收光谱法研究阿魏酸哌嗪和牛血清白蛋白结合反应的特征,并利用同步荧光法和三维荧光法研究了阿魏酸哌嗪与牛血清白蛋白作用前后白蛋白的构象变化.研究表明:阿魏酸哌嗪与牛血清白蛋白形成复合物,从而猝灭牛血清白蛋白的内源性荧光.该过程为静态猝灭过程.根据Stem-Volmer方程求出不同温度下的结合位点数和结合常数;根据Fsmter非辐射能量转移理论可求出其作用距离r=2.33nm:根据基本热力学参数△H、△S和△G判断阿魏酸哌嗪和牛血清白蛋白主要通过氢键和范德华力发生相互作用.