氮混杂金属卟啉吸收光谱性质的理论研究

采用密度泛函理论在B3LYP/6-31+G(d)水平上研究了4种金属Mg, Ni, Cu, Zn配位的自由卟啉(FBP)及氮混杂卟啉(NECP)的几何结构及分子轨道能级. 采用含时密度泛函理论(TD-DFT)方法计算了金属与2种卟啉配位后在气体条件下的电子吸收光谱, 包括激发能、 吸收波长、 跃迁组成和振子强度.计算结果表明, 与金属配位的FBP(M-FBP)具有D_4h对称性, 分子轨道能级HOMO/HOMO-1和LUMO/LUMO+1因能级相近发生简并, HOMO-LUMO轨道能级差大约3.0 eV, 在Soret带出现较强吸收峰.由于C/N原子位置的改变, 非对称性结构的M-NECP前线轨道组成发生改变, 轨道能级差(HOMO-LUMO)减小至2.6 eV左右, 且能级发生分裂, Soret带出现多个电子吸收谱峰, Q带也出现吸收峰. 本文研究了水、 氯仿和苯3种不同极性溶剂对M-FBP和M-NECP的分子轨道及电子吸收光谱的影响, 结果表明, 随溶剂极性减弱金属配合物的电子吸收光谱发生红移, 并且吸收峰强度增强.     

第三组份端基对有机太阳能电池性能的影响（英文）

我们用宽带隙聚合物FTAZ(苯并二噻吩-二氟苯并氮三唑共聚物)作为给体,窄带隙稠环电子受体FOIC(六噻吩稠环-氟代腈基茚酮类化合物)作为受体,中带隙稠环电子受体IDT-IC (引达醒-腈基茚酮类化合物)和IDT-NC (引达醒-腈基苯并茚酮类化合物)分别作为第三组分,制备了三元共混有机太阳能电池,研究了第三组分端基对器件性能的影响。IDT-IC和IDT-NC具有相似的化学结构,仅端基不同;IDT-IC端基是苯环,而IDT-NC端基是萘环。与IDT-IC相比,IDT-NC吸收光谱红移40nm,LUMO能级下移0.11 eV,电子迁移率提高50%。基于FTAZ:FOIC,FTAZ:IDT-IC,FTAZ:IDT-NC二元共混体系的有机太阳能电池效率分别为9.73%,7.48%,7.68%。FTAZ:FOIC:IDT-IC和FTAZ:FOIC:IDT-NC三元共混器件的效率分别提升到11.2%和10.4%。对于FTAZ:FOIC:IDT-IC三元共混器件,由于IDT-IC比FOIC具有更高的LUMO能级,开路电压(V_(OC))随着IDT-IC含量的增多而增加。由于IDT-IC与FOIC吸收光谱高度互补,短路电流(J_(SC))也显著提高。第三组份IDT-IC的加入改善了薄膜形貌和载流子传输,填充因子(FF)有所提高。对于FTAZ:FOIC:IDT-NC三元共混器件,由于IDT-NC比FOIC具有更高的LUMO能级,V_(OC)随着IDT-NC含量的增多而增加;但由于IDT-NC的LUMO能级比IDT-IC的LUMO能级低,其V_(OC)比FTAZ:FOIC:IDT-IC体系低。由于FOIC和IDT-NC吸收光谱高度重叠,J_(SC)降低。第三组份IDT-NC的加入改善了薄膜形貌和载流子传输,FF提高,甚至比FTAZ:FOIC:IDT-IC体系有更好的载流子传输和FF。     

金属酞菁及其衍生物的紫外-可见光谱性能研究

用紫外-可见吸收光谱对金属酞菁及其衍生物进行研究,分析了酞菁的不同d电子数、不同价电子数和不同取代基对Q带和B带的影响。研究结果表明,d电子数增加,HOMO-LUMO分子轨道间能级差降低,电子光谱发生红移。金属酞菁中金属电荷对Q带影响不大,而随着电荷的增加,对B带有一定影响。Schiff基团的引入对Q带产生一定的影响,前线轨道能级裂分导致Q带红移并出现了不同程度的裂分。特别是二茂铁基团的酞菁金属配合物具有极高的非线性光学性能,有望开发成用于光动力诊疗的新型光敏剂。     

Pd_xNi/C催化剂增强机理的密度泛函理论研究

通过交替微波法制备了PdxNi/C(x=1～4)催化剂,并对其形貌、结构及电化学性能进行了表征.结果表明,通过在Pd中掺杂Ni原子,其对氧还原反应(ORR)的催化活性较纯Pd的高.同时采用密度泛函理论(DFT)计算了一系列简化的团簇模型.计算结果表明,随着Ni的加入,纳米颗粒的最高占据轨道(HOMO)与最低空轨道(LUMO)能级增加,且两能级间隙(HLG)减小.因此在ORR中,一方面由于LUMO被抬高,降低了电子亲和能,带负电的催化剂颗粒更易将电子传递给O2,另一方面由于HLG减小,电中性颗粒HOMO上的电子也容易失去.这两方面的作用使其对O2还原活性得以增强.Fukui指数结合DFT方法和Mulliken布居分析指出,表面的Pd原子为催化剂团簇的活性中心.     

蓝光萘酰亚胺发光材料的合成与表征

通过在4位引入不同芳香基团,采用Suzuki和Stille偶联反应,设计与合成了一系列新型1,8-萘酰亚胺类荧光染料,并研究了它们的紫外-可见吸收、荧光发射和电化学行为等光物理性质。这些化合物在甲苯中均发射蓝色荧光,最大吸收和荧光发射峰分别在357～378和423～451nm之间,且随着芳香基团供电性增强,吸收和荧光发射波长发生红移。芳香基团的结构对化合物的发光效率影响很大,其中,取代基为甲氧基苯的化合物具有最高的荧光量子效率,可达0.98,而取代基为噻吩的化合物荧光量子效率最低,只有0.17。电化学循环伏安研究表明该类化合物具有较高的电子亲合力,不同芳香基团的引入只影响化合物的被占分子轨道(HOMO)能级,而对化合物的最低空分子轨道(LUMO)能级没有影响,即LUMO能级由1,8-萘酰亚胺单元决定。     

苯环上氯原子的不同取代位置对四苯基锌卟啉-酪氨酸光物理性质的影响

稳态紫外光谱、荧光光谱和时间分辨荧光光谱显示,苯环上氯原子的不同位置对氯苯基锌卟啉-酪氨酸的光物理性质有很大影响.紫外吸收光谱中,邻、间和对氯取代的3个化合物都具有典型的Soret带和Q带.其中Soret带位于423nm处,Q(0,0)和Q(0,1)带分别位于549和590nm处.邻位取代化合物的荧光量子产率为0.058,比间位(0.0241)、对位(0.0235)取代化合物的要高得多.邻位取代化合物的荧光寿命(3.11ns)比间位(1.12ns)和对位(1.11ns)取代化合物的长.邻位化合物的这些特性可能归因于取代基之间的空间效应;而在间位和对位化合物中,重原子效应和吸电子的诱导效应可能起主导作用.     

推/拉电子取代基对PCBM结构及光谱性质影响的理论研究

应用密度泛函理论(DFT)方法计算[6,6]-苯基-C₆₁-丁酸甲酯(PCBM)及其苯环对位取代得到的4种衍生物的几何和电子结构. 采用第一激发能校正了分子的最低未占据分子轨道(LUMO)能级, 探讨了推/拉电子基团对分子前线轨道的影响. 在全优化几何构型的基础上, 采用含时密度泛函理论(TD-DFT)方法研究了电子吸收光谱特征和电荷转移态性质, 并讨论了推/拉电子基团对体系电子吸收光谱性质的影响. 通过对重组能和电子亲和势的计算, 预测了PCBM与4种衍生物的电子能力及电子迁移率大小的关系. 结果表明, 在PCBM中, 在苯环的对位引入推电子基团可以提高分子的前线轨道能级, 改变前线轨道电子云分布, 明显增强可见光范围内的吸收强度, 增加可见光范围内的电荷转移吸收, 且激发态的电荷转移随着引入基团推电子能力的增加而增强. 化合物5的激发态分子内电荷转移性质最强, 且具有较独特的光伏性质. 而在同样位置引入拉电子基团, 则降低了分子前线轨道能级对电子吸收光谱的影响.     

硫砜类双极性蓝色磷光主体材料的合成及性能

设计并合成了一种基于硫砜类的双极性蓝色磷光主体材料2-(10H-吩噁嗪基)噻吨-9-酮-10,10-二氧化物(TXOPXZ),并用1 HNMR、13 CNMR和元素分析对其结构进行了表征。通过紫外-可见(UV-Vis)、荧光、低温磷光、循环伏安法、热重分析(TGA)、差热分析(DSC)和密度泛函理论(DFT)对其性能和能级结构进行了研究。结果表明:TXOPXZ在二氯甲烷稀溶液中的最大吸收峰位于285nm;发射峰位于439nm;低温(77K)磷光光谱的第一发射峰位于460nm,其三重态能级为2.70eV,可与蓝色磷光材料FIrpic(2.62eV)的能级匹配;循环伏安法测得TXOPXZ的HOMO能级为-5.28eV,与阳极ITO的功函(-4.5~-5.0eV)相匹配,LUMO能级为-1.95eV,与电子传输材料TAZ(-2.30eV)的LUMO能级相匹配,表明TXOPXZ具有良好的双极性能;TGA数据表明其分解温度为329℃,具有良好的热稳定性,DSC显示其Tg温度为191℃,表明其具有无定形结构和良好的成膜性。     

锰(III)5,10,15-三(五氟苯基)-Corrole配合物的DFT计算

在6-31G*水平上采用DFT(UB3LYP)方法对锰(III)5,10,15-三(五氟苯基)-corrole [(TPFC)MnIII]及其咪唑轴向配位加合物(TPFC)MnIII(Im)进行了几何结构全优化. 计算结果表明, 咪唑的配位作用不会改变其基态的高自旋(s=2)特性. (TPFC)MnIII与咪唑配位形成轴向加合物后, 其中心金属Mn原子偏离平面结构, 与corrole大环N4平均平面的距离达到0.02734 nm. NBO分析显示(TPFC)MnIII和(TPFC)MnIII(Im)中心金属锰的电子组态为(dxz)1(dyz)1(dz2)1(dx2-y2)1(dxy)0. (TPFC)MnIII(Im)前线分子轨道能级明显上升, 从其β-(LUMO+3)轨道可见咪唑配位N原子的py轨道与中心金属Mn原子dyz轨道形成了d-pπ轨道. TD-DFT计算发现, (TPFC)MnIII和(TPFC)MnIII(Im)电子光谱Q带的“四轨”特征比B 带明显; (TPFC)MnIII的CT带主要源自β-(HOMO-1)→β-(LUMO+5)和β-HOMO→β-(LUMO+4)的跃迁, (TPFC)MnIII(Im)的CT带则主要源自β-(HOMO-1)→β-(LUMO+3)和β-HOMO→β-(LUMO+4)的跃迁.     

锰（Ⅲ）5,10,15-三（五氟苯基）-Corrole配合物的DFT计算

在6-31G*水平上采用DFT(UB3LYP)方法对锰(Ⅲ)5,10,15-三(五氟苯基)-corrole[(TPFC)MnⅢ]及其咪唑轴向配位加合物(TPFC)MnⅢ(Im)进行了几何结构全优化.计算结果表明,咪唑的配位作用不会改变其基态的高自旋(s=2)特性.(TPFC)MnⅢ与咪唑配位形成轴向加合物后,其中心金属Mn原子偏离平面结构,与corrole大环N4平均平面的距离达到0.02734 nm.NBO分析显示(TPFC)MnⅢ和(TPFc)MnⅢ(Im)中心金属锰的电子组态为(dxz)1(dyz)1(dz2)1(dx2-y2)1(dxy)0(TPFC)MnⅢ(Im)前线分子轨道能级明显上升,从其β-(LUMO+3)轨道可见咪唑配位N原子的py轨道与中心金属Mn原子撕道形成了d-pπ轨道.TD-DFT计算发现,(TPFC)MnⅢ和(TPFC)MnⅢ(Im)电子光谱Q带的"四轨"特征比B带明显;(TPFC)MnⅢ的CT带主要源自β-(HOMO-1)→β(LUMO+5)和β-HOMO→β-(LUMO+4)的跃迁,(TPFC)MnⅢ(Im)的CT带则主要源自β-(HOMO-1)→β-(LUMO+3)和β-HOMO→β-(LUMO+4)的跃迁.     

给电子基团对吲哚染料电子结构和吸收光谱的影响

利用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT), 分别基于B3LYP和PBE1PBE方法研究了一系列含有不同给电子基团的吲哚染料分子(ID1-ID3)的电子结构和吸收光谱性质. 重点比较了不同电子给体对染料的分子结构、吸收光谱以及其在电池中的光伏性能的影响. 结果表明从ID1、ID2到ID3, 随着电子给体中苯环数目的增加, 吲哚分子上的共轭效应逐渐增大, 导致吲哚分子最高占据分子轨道-最低未占据分子轨道(HOMO-LUMO)之间的能隙变窄, 分子的吸收光谱发生红移. 染料分子的吸收光谱和LUMO能级分别影响染料的吸光效率和光电转化过程中电子的注入过程, 从而使其二者成为决定电池光伏性能的重要参数. 综合考虑上述两个参数对电池性能的贡献, 通过理论研究证实, 在ID1-ID3系列染料中, ID3具有较长的吸收谱带、较大的分子消光系数和合适的LUMO能级, 从而表现出最为优越的光伏性能, 这与实验得出的结论很好地吻合.     

Single site electronic spectroscopy of magnesium isobacteriochlorin in n-octane matrixes at 7 K

The high resolution, single site emission and absorption spectra of magnesium isobacteriochlorin (MgiBC) in n-octane matrixes at 7 K are reported. Its emission and Q and Soret band absorption regions have been investigated. The vibrational frequencies of the ground and the lowest energy pipi* singlet excited states were determined from luminescence and excitation spectra, respectively. The emission from MgiBC at 7 K seems to be entirely fluorescence. The luminescence and Q(y) region spectra of the complex are similar, having intense, narrow origin bands followed by relatively weak, but orderly vibrational structure. The Q(x) region does not have a clear origin and exhibits complex vibrational structure that increases in intensity going to higher energy. In the Soret region the individual pipi* origins are clearly identifiable and some vibrational structure was also observed.     

A New Water‐Soluble Phosphorus‐Dipyrromethene and Phosphorus‐Azadipyrromethene Dye: PODIPY/aza‐PODIPY

PODIPY and aza‐PODIPY have been successfully prepared by the treatment of dipyrromethene and azadipyrromethene with POCl₃ in the presence of Et₃N. The new PODIPY and aza‐PODIPY dyes are found to have photophysical properties. PODIPY and aza‐PODIPY are water‐soluble, and aza‐PODIPY is suited for labeling living Hep‐2 cells for imaging assays in the near‐infrared region. Molecular orbital calculations show that the increase in the HOMO–LUMO band gap for the lowest energy absorption bands is observed in the new phosphorus‐containing aza‐PODIPY, and the HOMO and LUMO energies of aza‐PODIPY are found to be higher than those of aza‐BODIPY.     

An oligomer study on small band gap polymers

Small band gap polymers may increase the energy conversion efficiency of polymer solar cells by increased absorption of sunlight. Here we present a combined experimental and theoretical study on the optical and electrochemical properties of a series of well-defined, lengthy, small band gap oligo(5,7-bis(thiophen-2-yl)thieno[3,4-b]pyrazine)s ( E g = 1.50 eV) having alternating donor and acceptor units. The optical absorptions of the ground state, triplet excited state, radical cation, and dication are identified and found to shift to lower energy with increasing chain length. The reduction of the band gap in these alternating small band gap oligomers mainly results from an increase of the highest occupied molecular orbital (HOMO) level. The S 1-T 1 singlet-triplet splitting is reduced from approximately 0.9 eV from the trimeric monomer to -0.5 eV for the pentamer. This significant exchange energy is consistent with the fact that both the HOMO and the lowest unoccupied molecular orbital (LUMO) remain distributed over virtually all units, rather than being localized on the D and A units.     

吡唑啉衍生物的电化学性质及其能带结构

有机 /聚合物电致发光是当今世界上的热门研究领域[1 ,2 ] ,因而有机 /聚合物电致发光材料的能带结构成为非常重要的研究课题[3] .目前 ,确定有机 /聚合物电致发光材料的能带结构的方法主要有电化学法[4] ,光谱法[5] ,量子化学计算法[6] ,紫外光电子能谱法[7] ,光电子发射法[8] 等 .这些方法中 ,由于电化学方法操作简单 ,对仪器设备要求不高 ,故被广泛使用 .虽然不同的测试方法测得的能带数据存在一定的系统误差 ,但由于电发光器件中考虑的是材料间的能带匹配 ,因此 ,在不同的条件下测定的能带数据相对来说是可信的 .吡唑啉化合物具有较高的…     

Toward a rational design of poly(2,7-carbazole) derivatives for solar cells

On the basis of theoretical models and calculations, several alternating polymeric structures have been investigated to develop optimized poly(2,7-carbazole) derivatives for solar cell applications. Selected low band gap alternating copolymers have been obtained via a Suzuki coupling reaction. A good correlation between DFT theoretical calculations performed on model compounds and the experimental HOMO, LUMO, and band gap energies of the corresponding polymers has been obtained. This study reveals that the alternating copolymer HOMO energy level is mainly fixed by the carbazole moiety, whereas the LUMO energy level is mainly related to the nature of the electron-withdrawing comonomer. However, solar cell performances are not solely driven by the energy levels of the materials. Clearly, the molecular weight and the overall organization of the polymers are other important key parameters to consider when developing new polymers for solar cells. Preliminary measurements have revealed hole mobilities of about 1 x 10(-3) cm2 x V(-1) x s(-1) and a power conversion efficiency (PCE) up to 3.6%. Further improvements are anticipated through a rational design of new symmetric low band gap poly(2,7-carbazole) derivatives.     

Single site electronic spectroscopy of palladium chlorin in n-octane matrixes at 7K

The high resolution, single site emission and absorption spectra of palladium chlorin (PdC) in n-octane matrixes at 7K are reported. The emission and Q and Soret band absorption regions were investigated. The vibrational frequencies of the ground and the lowest energy pipi* excited states were determined from luminescence and excitation spectra, respectively. The emission from PdC was entirely phosphorescence. The emission and Qy region spectra of the complex are similar, having intense, narrow origin bands followed by relatively weak but orderly vibrational structure. The Qx region of this metal chlorin does not have a clear origin and exhibits complex vibrational structure which increases in intensity going to higher energy. In the Soret region of PdC there is only a single intense, broad band.     

有机/聚合物材料体系能带结构的表征电化学方法研究

以８－羟基喹啉铝和聚（Ｎ－乙烯基）趾唑为例,采用多种电化学方法确立了有机聚合物半导体材料的最高占有轨道和最低空轨道能级的位置,所得数据与光电子发射法表征结果一致。用电化学方法测得的带隙Ｅｇ＾ｅｌ与吸收光谱法得到的Ｅｇ＾ｏｐｔ吻合。用测得的能带结构参数为依据研制的电致发光器件的发光性能很高。     

Porphyrins with exocyclic rings. 14. Synthesis of tetraacenaphthoporphyrins, a new family of highly conjugated porphyrins with record-breaking long-wavelength electronic absorptions

The Soret band for porphyrins is usually observed in the near-ultraviolet at approximately 400 nm, and few examples of "nonexpanded" porphyrins with this major absorption band at values above 500 nm have previously been reported in the literature. Ring fusion with aromatic ring systems such as naphthalene, anthracene, or phenanthrene generally only produces minor bathochromic shifts to this diagnostic absorption band. In this paper, the synthesis of a series of tetraacenaphthoporphyrins and their metal chelates is reported. The compact nature of the acenaphthylene ring system allows the introduction of meso substituents using the Lindsey methodology. meso-Tetraphenylporphyrin 10a shows the presence of a Soret band at 556 nm, while p-methoxy and p-nitro substituents in 10f and 10g, respectively, further shift this band to 560 and 570 nm. Addition of TFA produces the corresponding dications with slightly higher wavelength Soret bands at 565, 573, and 588 nm. These values compare to 525 nm for the dication of tetraacenaphthylene 8, which lacks the meso-aryl substituents, indicating that steric crowding and its resulting distortion of the macrocyclic conformation is responsible for a significant albeit minor portion of these shifts. The nickel(II), copper(II), and zinc chelates of 10a produce Soret bands at 528, 545, and 558 nm, respectively, demonstrating that the trend for increasing red shifts in metalloporphyrins across the periodic table is retained for this series. The lead(II) chelate 19d gave an additional "hyper" shift that brought the Soret band to 604 nm. A similar red shift could be achieved by introducing four phenylethynyl substituents at the meso positions, and this highly conjugated porphyrin (20) also showed a Soret band at 604 nm, while the corresponding dication afforded this absorption band at 629 nm. The essentially additive "hyper" shift due to lead chelation brought the Soret band for the related lead(II) complex 22d to 642 nm. These effects are by far the largest ever observed for true porphyrins and demonstrate that the Soret band can be fined tuned to virtually any part of the visible spectrum.