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1.
金属卟啉在光激发条件下会呈现出重要催化特性和光学性质。四苯基卟啉亚钴(Co~Ⅱ TPP)性质稳定,难以通过强氧化剂氧化至四苯基卟啉钴(Co~ⅢTPP)。本文分别利用全波长氙灯与355nm激光脉冲诱导Co~Ⅱ TPP,探究其分子内的氧化还原过程。研究发现,Co~Ⅱ TPP的Soret带最大吸收峰随光照时长的递增出现红移,且吸收强度呈现先下降后上升的趋势,最大吸收峰位置由415nm逐渐红移至433nm,其Q带最大吸收峰位置由532nm逐渐红移至545nm。两种光源诱导Co~Ⅱ TPP均出现稳态吸光度的降低,分子内的活性中心钴离子由Co~(2+)氧化到Co~(3+)。咪唑使得Co~Ⅱ TPP受光诱导后更易出现稳态吸收峰红移。Co~Ⅱ TPP的瞬态吸收光谱有3个瞬态吸收峰,激光激发含咪唑的Co~Ⅱ TPP溶液仅在396nm出现单个瞬态吸收峰。数据表明光激发时,电子从卟啉的π成键分子轨道向具有配体特征的π~*反键分子轨道迁移,发生金属对配体的电荷迁移,生成稳定的高价态Co~Ⅲ。  相似文献   

2.
采用Adler法合成了Meso-四(对羟基苯基)卟啉(THPP), 在均相体系中使聚甲基丙烯酸缩水甘油酯(PGMA)与THPP发生开环反应, 得到侧链键合有羟基苯基卟啉的线型PGMA(HPP-PGMA); 进一步使HPP-PGMA与锰离子发生配合作用, 得到侧链键合有锰卟啉(MnP)的线型PGMA(MnP-PGMA), 测定了HPP-PGMA的1H NMR谱, 表征了其化学结构; 测定了HPP-PGMA与MnP-PGMA的UV-Vis光谱及荧光发射光谱, 考察了其光物理行为. 实验结果表明, 通过THPP外环上羟基与PGMA侧基环氧键的开环成醚反应, 可以顺利地将羟基苯基卟啉及其锰配合物键合在PGMA的侧链上. HPP-PGMA具有THPP的特征电子吸收光谱与荧光发射光谱, 且随着THPP键合度的增加, 光谱的强度增强. MnP-PGMA具有小分子锰卟啉的特征电子吸收光谱与荧光特征, 其Soret吸收带发生显著红移(红移58 nm), Q吸收带的数量减为3个吸收峰; 实验发现, MnP-PGMA与小分子锰卟啉类似, 在Q发射带没有荧光发射.  相似文献   

3.
高分子光伏材料聚对苯撑乙烯撑(PPV)由于低廉的价格, 容易加工的性能与可调的光学性能, 有可能成为新一代太阳能材料. 然而PPV较宽的带隙阻碍了PPV太阳能电池效率进一步提高. 合成了一种较低带隙的新型高分子光伏材料 PPV-PQ. 用NMR, FT-IR, 元素分析, GPC和TGA与循环伏安法对PPV-PQ进行了结构表征与性能检测, 并对它在氯仿溶液与固态薄膜下的紫外-可见吸收与荧光发射光谱进行了研究. 结果显示, 由于在固态下存在较强的分子间作用, 分子链的共平面性增加, 所以PPV-PQ无论是紫外-可见吸收, 还是荧光发射光谱, 在固态薄膜下都比在氯仿溶液里发生明显红移. 即使在浓溶液中, 分子链间也存在较强的作用力, 使得PPV-PQ荧光发射峰随溶液浓度的增加而发生红移. 紫外-可见光谱显示, PPV-PQ由于大体积的吸电子单元引起了较大的空间位阻, 最大吸收峰比PPV稍微蓝移, 但吸收却比PPV向长波延展, 带隙比PPV低, 只有1.92 eV. 循环伏安法结果表明PPV-PQ与PCBM两者的LUMO之间有足够的能量差异, 加上PPV-PQ与富勒烯衍生物C117共混物薄膜发生荧光猝灭, 都说明PPV-PQ上光激发电子能够转移到富勒烯衍生物上. 因此, PPV-PQ可以用作高分子光伏材料.  相似文献   

4.
圆二色谱和紫外可见光谱研究抗体-卟啉的相互作用   总被引:1,自引:0,他引:1  
圆二色谱(CD)和紫外可见光谱(UV-VIS)可用来研究单克隆抗体(McAb)-卟啉之间的相互作用,卟啉形成McAb-卟啉复合物,在Soret带区域最大吸收峰有显著红移和增色现象,在350-450nm区域,形成复合物时能检测诱导的CD光谱。CD光谱遵守朗伯-比尔定律,显示等吸收行为。McAb-卟啉复合物的紫外可见吸收及诱导的CD光谱在PH6-11的范围内保持不变,说明复合物异常稳定,也说明McAb-卟啉结合位点之间疏水相互作用是主要因素。  相似文献   

5.
采用溶胶-凝胶法在石英玻璃衬底上用旋涂法制备了TiO2薄膜样品,对样品在800-1100℃范围内进行退火处理,并对样品进行了拉曼光谱、透射光谱和荧光发光(PL)光谱测试.拉曼谱测试表明,随退火温度的升高,样品由锐钛矿相经锐钛矿与金红石的混相最终变为金红石相.透射谱测试表明,样品的吸收带边随着样品的相转换而发生红移.在总的趋势上,样品的折射率n随相转换而升高,厚度d和带隙Eg随相转换而降低.荧光发光光谱测试表明,在557-570nm和794-812nm范围内出现了两个发光光谱带.随着相转换,557-570nm范围内的发光光谱强度由强到无,而794-812nm范围内的发光光谱强度由弱到强.  相似文献   

6.
张晓丹  曹阳  贺军辉 《化学学报》2009,67(12):1277-1284
在溶液中以正己硫醇作稳定剂, 利用HAuCl4与HF处理后的硅纳米线(SiNWs)的氧化还原反应, 在SiNWs表面负载金纳米粒子(AuNPs). 通过调整HAuCl4的浓度, 得到了AuNPs粒径从3.2到7.0 nm的AuNPs/SiNWs复合结构, 并对这种复合结构进行了紫外-可见吸收光谱和荧光光谱研究. 紫外-可见吸收光谱研究表明, 负载不同粒径的AuNPs的SiNWs在530~580 nm间有明显的由AuNPs表面等离子体共振引起的吸收, 且随着AuNPs粒径的增加, 该吸收峰发生红移. 负载前后的荧光光谱表明, 在红光和绿光区负载AuNPs的SiNWs的荧光峰与HF处理后SiNWs的荧光峰峰形相当, 峰位变化不大; 但在蓝光区, 不同于HF处理前后SiNWs的发射峰(464 nm左右), 负载了AuNPs的SiNWs在423 nm的位置处出现了强荧光峰, 这个峰是AuNPs费米能级的电子与sp或d带的空穴辐射复合产生的.  相似文献   

7.
基于卟啉衍生物红光材料的合成及物性研究   总被引:1,自引:0,他引:1  
利用Schiffbase反应合成了两个卟啉衍生物TPP-AQ,TPP-PD.通过循环伏安、紫外可见吸收光谱、荧光光谱及理论计算等对其物性进行了研究.结果显示:TPP-AQ,TPP-PD氧化电位分别为E1/2=1.07,1.30V和1.21,1.36V,与TPP-PD相比,TPP-AQ的两个氧化还原电位都发生了负移;TPP-AQ与TPP-PD的最大紫外可见吸收峰分别在441和431nm,TPP-AQ的吸收波长较TPP-PD有一定程度的红移,通过理论计算可知这是由于TPP-AQ共轭程度优于TPP-PD导致的.TPP-AQ和TPP-PD的荧光主发射峰分别在657和656nm,半峰宽分别为30和27nm,有较好的红光色纯度.  相似文献   

8.
meso-四[(4-苯乙烯氨基)苯基]卟啉合成及其波谱特点   总被引:2,自引:2,他引:0  
陈林  佟珊玲  吴雅红  余坚  阎雁 《应用化学》2013,30(3):290-294
以吡咯和对硝基苯甲醛为原料,经过环化、还原和缩合,合成了meso-四[(4-苯乙烯氨基)苯基]卟啉(TBAPP),通过UV-Vis、FT-IR、1H NMR及元素分析等对产物进行了表征,并对其荧光和电子顺磁共振特性进行了研究。卟啉产物的EPR测定显示出游离基特征,表明卟啉分子的大π共轭结构对周边基团产生的自由基有稳定作用。取代基对卟啉的紫外-可见吸收、光致发光及电子顺磁共振特性均有影响。四席夫碱苯基卟啉TBAPP的Q带比前体四氨基卟啉(TAPP)和母体四硝苯基卟啉(TNPP)红移,而Soret谱带变化较小;TBAPP的440 nm光激发的最大荧光峰658 nm分别比TAPP蓝移5 nm和比TNPP红移9 nm;TBAPP的EPR精细结构比TAPP弱,而比TNPP强。  相似文献   

9.
纳晶的制备及其光谱的尺寸依赖性   总被引:1,自引:0,他引:1  
用再沉淀法制备了纳米晶体,向体系中加入水溶性高分子聚乙烯醇(PVA)可有效地抑制纳晶的生长,从而制得了稳定的具有不同粒径的纳晶.光谱研究表明,随着纳晶粒径增加,由于纳晶中分子间相互作用的变化,其吸收峰和激发峰位置都发生了红移,同时纳晶中激基缔合物的荧光发射峰强度减弱,荧光寿命有所延长.  相似文献   

10.
利用密度泛函和含时密度泛函理论对卟啉(FBP)、 单氮杂卟啉(N/Neo-CPs)、 双氮杂卟啉(DNCPs)及双混氮杂卟啉(Neo-C-NCPs)的结构与电子吸收光谱进行了研究. 结果表明, 由于N/C位置改变, 分子对称性和轨道组成发生改变, 氮杂卟啉中2-NCP-2H, 2,18-DNCP-2H 和1,17-Neo-C-NCP的各前线和近前线轨道能级发生较大变化, 光谱峰红移较显著; 电子-空穴分布图表明3类氮杂卟啉电子跃迁途径更丰富. 进一步探讨了水、 氯仿和苯3种溶剂对4类卟啉分子的影响. 结果表明, 随着溶剂极性减小, FBP, N-/Neo-CPs, DNCPs和Neo-C-NCPs的Q带吸收峰红移越明显, 吸收略有增强.  相似文献   

11.
Carbon-doped anatase TiO(2) was prepared by a facile hydrothermal process without adding additional carbon source. The as-prepared sample shows highly efficient photocatalytic activity, which only requires 4min and is about 11 times higher than that of Degussa P25 TiO(2) in degradation of methyl orange (MO) dye under UV light irradiation. Moreover, a highly visible-light activity is also observed. UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy confirm that the carbon atoms are incorporated into the interstitial positions of TiO(2) lattice and form a strong interaction with titanium atoms and extend photoresponding range to 700nm. Surface photovoltage spectra (SPS) and transient photovoltage (TPV) suggest that the presence of interstitial carbons induce several localized occupied states in the gap, enhance the separation extent and restrain the recombination of the photo-induced electron and hole carriers in TiO(2).  相似文献   

12.
采用改性的TiCl4水解法制备出三种不同表面性质的TiO2-X(X=5,10,20,X表示加入NaOH的浓度,单位为mo·lL-1)样品.利用(1,10-邻菲咯啉)2-2-(2-吡啶基)苯咪唑钌混配配合物(Rup2P)作为敏化剂,制备出Rup2P/TiO2-5/ITO(铟锡金属氧化物)、Rup2P/TiO2-10/ITO和Rup2P/TiO2-20/ITO表面敏化薄膜电极.测试结果表明三种薄膜电极的光电转换效率Rup2P/TiO2-10/ITO最高,Rup2P/TiO2-20/ITO次之,Rup2P/TiO2-5/ITO最低.利用吸收光谱、表面光电压(SP)谱、荧光光谱和表面光电流作用谱等分析了Rup2P和三种TiO2的能带结构和表面性质;利用光致循环伏安和表面光电流作用谱研究了三种Rup2P/TiO2-X/ITO薄膜电极的光致界面电荷转移过程.结果表明,在光致界面电荷转移过程中,TiO2层表面氧空位对Rup2P/TiO2-X/ITO薄膜电极光致电荷转移产生重要影响.并进一步讨论了Rup2P/TiO2-X/ITO薄膜电极的光电流产生机理.  相似文献   

13.
Triad hybrid multilayers containing the light sensitizers of zinc tetrapyridylporphyrin (ZnTPyP) and pyridine-functionalized TiO(2) (TiO(2)-Py) nanoparticles were constructed on substrate surfaces with the use of Pd(II) ions as the connectors using the layer-by-layer (LBL) method. The assembly process was monitored using ultraviolet-visible (UV-vis) absorption and X-ray photoelectron spectra as well as scanning electron microscopy and atomic force microscopy. The content of the pyridine substituents in the TiO(2)-Py nanocomposites was about 2% (w/w). The Soret absorption band of ZnTPyP was 24 nm red-shifted in the hybrid multilayers due to a strong intermolecular electronic coupling interaction among porphyrin macrocycles or porphyrin macrocycle/TiO(2)-Py nanoparticles. The average surface density of each ZnTPyP layer was about 1.4 × 10(-10) mol/cm(2). Aggregation of the small TiO(2)-Py nanoparticles to larger domains with sizes up to hundreds of nanometers occurred in the hybrid multilayers; however, such an aggregation behavior was weaker than that in the solutions. The quartz substrate modified with the as-prepared Pd/ZnTPyP/Pd/TiO(2)-Py triad hybrid multilayers was used as a heterogeneous photocatalyst for the degradation of methyl orange (MO) under irradiation (λ > 420 nm) at room temperature with a catalytic efficiency of about 1.3 × 10(-3) MO/ZnTPyP·s. Without the use of the filter, the catalytic efficiency increased because both ZnTPyP and TiO(2)-Py nanocomposites acted as the light sensitizers. It is suggested that the present heterogeneous catalyst has the advantages of facile separation, high stability, structural controllability on the molecular and nanoscale level, and good recyclability.  相似文献   

14.
A stable colloidal TiO(2) has been prepared. The interaction of meso-tetrakis (4-sulfonatophenyl) porphyrin (TSPP) with colloidal TiO(2) was studied by absorption and fluorescence spectroscopy. Upon excitation of its absorption band, the fluorescence emission of TSPP was quenched by colloidal TiO(2). The bimolecular quenching rate constant (k(q)) is 1.78 x 10(11)M(-1)s(-1). The porphyrin can participate in the quenching process by injecting electrons from its excited states into the conduction band of TiO(2). The quenching mechanism is discussed on the basis of the quenching rate constant as well as the reduction potential of the colloidal TiO(2). Rehm-Weller equation was applied for the calculation of free energy change (DeltaG(et)).  相似文献   

15.
本文设计合成了未见文献报道的meso—N(4-(N-咔唑)丁烷氧苯基)卟啉(1)及其稀土金属配合物(Ln=Sm(2),Eu(3),Tb(4),Dy(5)).通过核磁共振氢谱、紫外.可见吸收光谱、元素分析和红外光谱对稀土金属卟啉配合物进行了表征,并研究了卟啉样品的荧光性质和表面光电压性质.结果表明,受无辐射跃迁等因素的影响,卟啉1~5的荧光强度和荧光量子效率依次减小.在无外加电场的情况下,稀土金属配合物2~5的表面光电压强度变化与荧光强度变化呈现相反的规律,充分表明荧光发射与表面光电压的相互竞争过程.不同性质的电场对金属卟啉配合物的电荷分离影响显著,在正电场和无外加电场情况下,配合物2~5的表面光电压信号强度依次增加.  相似文献   

16.
Interfacial electron transfer (ET) dynamics of 5,10,15-trisphenyl-20-(3,4-dihydroxybenzene) porphyrin (TPP-cat) adsorbed on TiO2 nanoparticles has been studied by femtosecond transient absorption spectroscopy in the visible and near-IR region exciting at 400 and 800 nm. TPP-cat molecule forms a charge transfer (CT) complex with TiO2 nanoparticles through the catechol moiety with the formation of a five-membered ring. Optical absorption measurements have shown that the Q-band of TPP-cat interacts strongly with TiO2 due to chelation; however, the Soret band is affected very little. Optical absorption measurements indicate that the catechol moiety also interacts with TiO2 nanoparticles showing the characteristic band of pure catechol-TiO2 charge transfer (CT) in the visible region. Electron injection has been confirmed by monitoring the cation radical, instant bleach, and injected electron in the conduction band of TiO2 nanoparticles. Electron injection time has been measured to be < 100 fs and recombination kinetics has been best fitted with a multiexponential function, where the majority of the injected electrons come back to the parent cation radical with a time constant of approximately 800 fs for both excitation wavelengths. However, the reaction channel for the electron injection process has been found to be different for both wavelengths. Excitation at 800 nm, found to populate the CT state of the Q-band, and from the photoexcited CT state electron injection into the conduction band, takes place through diffusion. On the other hand, with excitation at 400 nm, a complicated reaction channel takes place. Excitation with 400 nm light excites both the CT band of Cat-TiO2 and also the Soret band of TPP-cat. We have discussed the reaction path in the TPP-cat/TiO2 system after exciting with both 400 and 800 nm laser light. We have also compared ET dynamics by exciting at both wavelengths.  相似文献   

17.
Highly dispersed TiO2 nanoparticles were successfully synthesized by a wet impregnation method using SBA-15 as hard template for confining the growth of TiO2 nanocrystals, and then calcined at 550 degrees C in muffle furnace for 2 h. The as-synthesized samples were characterized with Fourier transform infrared spectra (FTIR), Raman spectroscopy, diffuse reflectance UV-visible spectroscopy (UV-vis), powder X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), nitrogen adsorption, transmission electron microscopy (TEM) and photoluminescence spectra (PL). It was found that SBA-15 contained abundant silanol groups after removal of triblock copolymers by ethanol extraction and could easily adsorb a great number of titanium alkoxide via chemisorption. After subsequent hydrolysis of the anchored Ti complexes and calcination of the amorphous TiO2, anatase TiO2 nanocrystals with spherical shape and uniform particle diameter of about 6 nm were formed. A blue shift was observed in UV-vis absorption spectra due to the quantum size effect of TiO2 nanoparticles. Moreover, the as-prepared TiO2 nanoparticles showed a high PL intensity due to an increase in the recombination rate of photogenerated electrons and holes under UV light irradiation.  相似文献   

18.
Optical absorption and photoluminescence (PL) properties of colloidal TiO(2) nanotubes, produced by the alkali hydrothermal method, were studied at room temperature in the range 300-700 nm. Nanotubes having an internal diameter in the range 2.5-5 nm have very similar optical properties, in contrast to the expected behavior for quasi-1-D systems. This is explained by the complete thermal smearing of all 1-D effects, due to the large effective mass of charge carriers in TiO(2), resulting in an apparent 2-D behavior of TiO(2) nanotubes.  相似文献   

19.
四甲基-四乙基钯卟啉的表面光伏特性研究   总被引:5,自引:1,他引:4  
合成了1,3,5,7-四甲基-2,4,6,8-四乙基卟啉(TMTEP)及其钯络合物(PdTMTEP),并利用表面光电压谱(SPS)和场诱导表面光电压谱(FISPS)技术对它们的表面光伏特性进行了研究。TETEP有较强的荧光发射,而PdTMTEP以磷光辐射为主,其光伏响应强度比TMTEP的强得多;在外电场诱导下,PdTMTEP的Soret带与Q带的光伏响应强度随外加正电场光伏响应强度的增加而增强,随外加负电场光伏响应强度的增加而减弱,并且在680,750nm处出现两个新的光伏响应带,这两个光伏响应带与极化子跃迁有关。  相似文献   

20.
金离子掺杂对二氧化钛光催化性能的影响   总被引:49,自引:0,他引:49  
利用高压钠灯作光源,在Au^3+-TiO2悬浮溶液中,通过紫外-可见吸光度与TOC测定证实亚甲基蓝能被快速脱色降解。金离子掺杂可大大提高TiO2的光催化活性,金离子的最佳掺杂摩尔分数为0.5%。通过表征催化剂的晶型,化学组成,荧光光谱,紫外-可见吸收光谱,电场诱导表面光电压谱,提示金离子改性的机理,紫外-可见吸收光谱证实金离子掺杂可增强催化剂在可见光区域的吸收能力,由于产生金杂质能级,金离子改性TiO2能被可见光激发。适量的金杂质能降低催化剂的荧光发射强度与电场诱导表面光电压谱强度。根据不同金离掺杂摩尔分数,荧光发射强度与电场诱导表面光电压谱强度从弱到强的排序与光催化活性比强到弱的排序是一致的。  相似文献   

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