N-芳基-N′-(4-乙氧基苯甲酰基)硫脲衍生物阴离子识别性能的光谱研究

利用紫外-可见吸收光谱及1H NMR考察了两种N-芳基-N′-(4-乙氧基苯甲酰基)硫脲作为受体分子与F-,Cl-,Br-,I-,CH₃COO-,H₂PO-₄,HSO-₄,NO-₃等阴离子的作用。结果表明,客体阴离子F-,CH₃COO-,H₂PO-₄可以与该类受体分子形成氢键配合物,溶液颜色由无色转变为黄色,而加入其他阴离子则无变化。测定了主客体配合物的稳定常数和化学配位比,对苯环上不同取代基的受体分子与不同阴离子客体的识别作用以及同一受体对不同阴离子的识别作用进行了比较,其识别性能呈现规律性变化, 提出了可能的配合物的结合模式。     

N-芳基-N＇-（4-乙氧基苯甲酰基）硫脲衍生物阴离子识别性能的光谱研究

利用紫外-可见吸收光谱及^1H NMR考察了两种N-芳基-N＇-（4-乙氧基苯甲酰基）硫脲作为受体分子与F^-，Cl^-，Br^-，I^-，CH3COO^-，H2PO4^-，HSO4^-，NO3^-等阴离子的作用。结果表明，客体阴离子F^-，CH3COO^-，H2PO4^-可以与该类受体分子形成氢键配合物，溶液颜色由无色转变为黄色，而加入其他阴离子则无变化。测定了主客体配合物的稳定常数和化学配位比，对苯环上不同取代基的受体分子与不同阴离子客体的识别作用以及同一受体对不同阴离子的识别作用进行了比较，其识别性能呈现规律性变化，提出了可能的配合物的结合模式。     

3种β-巯基乙胺类席夫碱分子荧光光谱的量子化学研究简

文章采用量子化学B3LYP方法,在6-31g基组水平下对3种β-巯基乙胺席夫碱进行几何构型优化,经振动分析,均未出现虚频率.在此基础上用TD-DFT方法计算了3种化合物的荧光光谱,所得计算值与实验值基本相符.理论计算表明,巯基乙胺类席夫碱化合物是性能较好的发光材料.     

Li9团簇体心立方结构的形成机理和结合能

本文提出了Li9团簇体心立方结构的形成机理,并对此结构的总能量随中心原子到顶点原子间核间距R的变化用芶氏改进的排列通道量子力学方法(MACQM)进行了计算。结果显示曲线在R = 4.77 a0处有一极小值 -67.160922 a.u.,这表明Li9团簇的体心立方结构是可能稳定存在的。在R趋于无穷大时这9个锂原子的总能量为 -66.852240 a.u.,所以形成Li9的总结合能为0.308682 a.u.。因此Li9 团簇的原子平均结合能是0.034298 a.u.或0.933 eV,它大于我们过去计算的Li5团簇正四面体中心结构的原子平均结合能0.632 eV、Li7 团簇正八面体中心结构的原子平均结合能0.674 eV和Li13 团簇正二十面体中心结构的原子平均结合能0.810 eV。故在体心正多面体结构Lin (n= 5 ,7,9,13)中,Li9的体心立方结构有最大的原子平均结合能,这也许是碱金属晶体的晶胞取体心立方结构的一个原因。     

2-羟基-1-萘甲醛半碳酰腙激发态分子内质子转移阴离子荧光识别

利用荧光光谱分析法,考察了2-羟基-1-萘甲醛半碳酰腙(L)作为受体分子与F~-、Cl~-、Br~-、I~-、SO_3~(2-)、NO_3~-、ClO_4~-、H_2PO_4~-、SO_4~(2-)、CH_3COO~-、CO_3~(2-)等阴离子的作用。研究结果表明,在乙腈溶液中该受体分子其酚羟基OH与—C=N—基N之间的分子内氢键强度较弱,引入CH_3COO-和CO_3~(2-)增强了分子内氢键强度,在波长495nm处出现激发态分子内质子转移(ESIPT)荧光,荧光滴定实验表明该受体分子与CH_3COO~-和CO_3~(2-)均形成1:1型结合物,提出了可能的配合物结合模式。     

聚合型铝氢化物(AlH3)n(n=1-3)的几何结构与振动光谱的研究

采用不同方法B3P86、B3LYP、B3PW91和MP2,结合Dunning的相关一致基组cc-PVTZ,对聚合型铝氢化物(AlH3)n(n=1-3)分子的可能几何构型进行优化计算,通过比较计算结果,发现密度泛函DFT中的方法B3P86计算的能量最低．本文采用B3P86方法得出最稳定构型的几何参数、电子结构、振动频率等性质参数,并给出最稳定结构的总能量(ET)、结合能(EBT)、平均结合能(Eav)、电离势(EIP)、能隙(Eg)、费米能级(EF)和差分吸附氢原子能(Ediff)．结果表明：三种铝氢化物分子基态都为1重态,电子态都为 ; AlH3分子的最稳定几何构型为 的平面三角形结构;Al2H6为对称性乙烯式 立体结构,H-Al之间生成氢桥式三中心双电子键;Al3H9为 立体结构,也生成氢桥式三中心双电子键,但三个氢桥三中心双电子键彼此隔离．最后分析了三种氢化物的红外和拉曼光谱、平均结合能、电离势、能隙和费米能级等特性,说明(AlH3)n(n=1-3)三分子中Al3H9最稳定,H-Al桥键键长比端键更长,红外光谱强度最大,差分吸附氢原子能最大,具有较强的储氢性能．     

3种对苯二甲醛类巯基席夫碱分子荧光光谱的量子化学研究

采用量子化学B3LYP方法,在6-31G基组水平下对3种对苯二甲醛类巯基席夫碱进行几何构型优化,经振动分析,均未出现虚频率。在此基础上用TD-DFT方法计算了3种席夫碱化合物的荧光光谱,所得计算值与实验值基本相符。理论计算表明,对苯二甲醛类巯基席夫碱是一类荧光性质较好的荧光化合物。     

聚合型铝氢化物(AlH3)n(n=1-3)的几何结构与振动光谱的研究

采用不同方法B3P86、B3LYP、B3PW91和MP2,结合Dunning的相关一致基组cc-PVTZ,对聚合型铝氢化物(AlH3)n(n=1-3)分子的可能几何构型进行优化计算,通过比较计算结果,发现密度泛函DFT中的方法B3P86计算的能量最低．本文采用B3P86方法得出最稳定构型的几何参数、电子结构、振动频率等性质参数,并给出最稳定结构的总能量(ET)、结合能(EBT)、平均结合能(Eav)、电离势(EIP)、能隙(Eg)、费米能级(EF)和差分吸附氢原子能(Ediff)．结果表明：三种铝氢化物分子基态都为1重态,电子态都为 ; AlH3分子的最稳定几何构型为 的平面三角形结构;Al2H6为对称性乙烯式 立体结构,H-Al之间生成氢桥式三中心双电子键;Al3H9为 立体结构,也生成氢桥式三中心双电子键,但三个氢桥三中心双电子键彼此隔离．最后分析了三种氢化物的红外和拉曼光谱、平均结合能、电离势、能隙和费米能级等特性,说明(AlH3)n(n=1-3)三分子中Al3H9最稳定,H-Al桥键键长比端键更长,红外光谱强度最大,差分吸附氢原子能最大,具有较强的储氢性能．     

1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙钳形受体对卤素阴离子的识别机理

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)和HF(Hatree-Fock)方法, 从理论上探讨了1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙(DAPHZ)钳形受体对卤素阴离子的识别机理,结果发现DAPHZ受体以其钳形结构中的-N-H基团与卤素阴离子间形成双侧红移氢键进行识别. 经BSSE校正后DAPHZ•••F-, DAPHZ•••Cl-和DAPHZ•••Br-体系的分子识别相互作用能ΔECP分别为-327.5,-163.5和-148.3 kJmol-1, 说明钳形DAPHZ受体对F-具有最好的识别能力. 此外, 采用自然键轨道(NBO)计算, 相关H原子化学位移计算及分子中原子(AIM)等理论分析了识别体系中红移氢键的电子结构和性质, 结果表明APHZ受体对卤素阴离子的识别能力的相对顺序为DAPHZ•••F- >> DAPHZ•••Cl- ≈ DAPHZ•••Br-.     

1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙钳形受体对卤素阴离子的识别机理

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)和HF(Hatree-Fock)方法, 从理论上探讨了1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙(DAPHZ)钳形受体对卤素阴离子的识别机理,结果发现DAPHZ受体以其钳形结构中的-N-H基团与卤素阴离子间形成双侧红移氢键进行识别. 经BSSE校正后DAPHZ•••F-, DAPHZ•••Cl-和DAPHZ•••Br-体系的分子识别相互作用能ΔECP分别为-327.5,-163.5和-148.3 kJmol-1, 说明钳形DAPHZ受体对F-具有最好的识别能力. 此外, 采用自然键轨道(NBO)计算, 相关H原子化学位移计算及分子中原子(AIM)等理论分析了识别体系中红移氢键的电子结构和性质, 结果表明APHZ受体对卤素阴离子的识别能力的相对顺序为DAPHZ•••F- >> DAPHZ•••Cl- ≈ DAPHZ•••Br-.     

基于TCNQ电荷转移化合物的合成与光谱性质

π电子受体TCNQ的电荷转移化合物有奇特的电学和磁学性质,在该类电荷转移化合物中,TCNQ的形态对化合物的性质有较大的影响。文章合成了两种电荷转移化合物[RBz(4-CH₃)Py][TCNQ](R=Br(1),I(2)),通过元素分析、红外光谱和拉曼光谱对其进行了表征。这两种化合物的元素分析结果显示与理论值一致。通常在2 200 cm-1附近的C≡N的伸缩频率经常被用来确定TCNQ分子的电荷,TCNQ中性分子的ν(CN)在2 222 cm-1以上,而这两种化合物的ν(CN)都向低波数移动,在2 185～2 156 cm-1之间。通过对两种化合物红外和拉曼光谱的测定,显示了其中的TCNQ形态是TCNQ阴离子自由基（TCNQ－）。     

Synthesis and photoinduced electron transfer characteristic of a bis (zinc porphyrin)‐perylene bisimide array

In this article, a donor–acceptor array consisting of two zinc porphyrin (ZnPOR) units attached to the 1,7‐positions of perylene‐3,4:9,10‐bis(dicarboximide) (PDI) was synthesized and characterized. This double‐wing molecule exhibits very broad absorption in the region from 300 to 900 nm. Especially, its lower energy absorption feature presumably arises from donor–acceptor interactions. The fluorescence emission spectra confirmed that photoinduced electron transfer occurred from POR to perylene bisimide moiety in this triad. In contrast to previously studied systems incorporating POR and PDI groups, this array shows the evidence of a relatively strong ground‐state electronic coupling between the donor and acceptor moieties. Additionally, highest occupied molecular orbital and lowest unoccupied molecular orbital values of the array were acquired by cyclic voltammetry (CV). The results showed that these energy values fulfill the energetic conditions required for the proposed electron transfer. More importantly, the photocurrent measurement showed that this molecule exhibits a high capacity to form a photoinduced charge‐separated state and to produce steady and prompt cathodic photocurrent responses. These results confirmed the role of this new array toward harvesting light energy and generating photocurrent during the operation of a photoelectrochemical cell. Copyright © 2011 John Wiley & Sons, Ltd.     

DFT study of CO adsorption on neutral and charged Pd<Subscript>n</Subscript>(n = 1–7) clusters

Density functional calculations have been performed to investigate CO adsorption on neutral, cationic and anionic Pd_n (n=1–7) clusters. From the results, it is observed that the binding of CO molecule to neutral and cationic palladium clusters takes place via 1-, 2- and 3-fold coordination. On the other hand, only terminal adsorption of CO molecule is possible in anionic clusters barring bridging adsorption in Pd₇ ^- cluster.     

Study of protein-probe complexation equilibria and protein-surfactant interaction using charge transfer fluorescence probe methyl ester of N,N-dimethylamino naphthyl acrylic acid

In this paper, we demonstrate the interaction between intramolecular charge transfer (ICT) probe—Methyl ester of N,N-dimethylamino naphthyl acrylic acid (MDMANA) with bovine serum albumin (BSA) using absorption and fluorescence emission spectroscopy. The nature of probe protein binding interaction, fluorescence resonance energy transfer from protein to probe and time resolved fluorescence decay measurement predict that the probe molecule binds strongly to the hydrophobic cavity of the protein. Furthermore, the interaction of the anionic surfactant sodium dodecyl sulphate (SDS) with water soluble protein BSA has been investigated using MDMANA as fluorescenece probe. The changes in the spectral characteristics of charge transfer fluorescence probe MDMANA in BSA-SDS environment reflects well the nature of the protein-surfactant binding interaction such as specific binding, non-cooperative binding, cooperative binding and saturation binding.     

盐离子对蛋白质带电特性的影响

本文应用分子理论,研究盐离子对蛋白质带电特性的影响,理论模型考虑蛋白质与阴离子的结合作用。研究发现,由于蛋白质与阴离子的结合,距离蛋白质表面附近处的阴离子被吸附在了蛋白质表面,在距离蛋白质表面附近区域,阴离子分布较少。通过计算体系中的静电势,我们发现,在距离蛋白质表面附近,静电势呈现了较大的负值,带正电荷的阳离子感受到静电吸引,会出现在距离蛋白质表面附近的区域,这会使得在距离蛋白质表面附近的区域,阳离子数目增多。这样,在不同阴离子浓度、以及阴离子与蛋白质不同结合能条件下,阴离子会在不同程度上影响蛋白质的带电特性、影响体系中的静电特性。通过考察不同结合能条件下,蛋白质表面电荷面密度随阴离子浓度的变化关系还发现,较大的结合能会使得阴离子与蛋白质结合增快,蛋白质表面会呈现从正电荷态向负电荷态的转变。理论结果符合实验观测,由此表明,盐离子与蛋白质的结合导致蛋白质表面带电特性的改变,是盐离子影响蛋白质带电特性的本质。     

Optical properties of the Ge donor and acceptor in GaP

The observation of discrete pair line emission and the analysis of the spectra from Ge donor - C acceptor and S donor - Ge acceptor pairs in GaP is reported. The Ge donor binding energy is 0.200 ± 0.002 eV and the Ge acceptor binding energy is 0.258 ± 0.002 eV. The bound exciton recombination at neutral Ge donors was observed at 2.265 eV corresponding to an exciton binding energy of 0.063 eV. This is the most tightly donor bound exciton observed in GaP.     

Electronic interaction between valence and dipole-bound states of the cyanoacetylene anion

The electron attachment properties of cyanoacetylene HCCCN are investigated with particular emphasis on the coupling between dipole-bound and valence states. As an initial step both the dipole-bound and the valence state of HCCCN^- are studied separately using high level ab initio methods. Predictions for the geometry of the valence anion, the electron binding energy of the dipole-bound state, the energy of the temporary anion associated with vertical attachment into the valence state, the vertical detachment energy of the valence anion, and the adiabatic electron affinity of HCCCN are given. Our results indicate that the electron affinity found in the NIST web-book is not that of HCCCN but of some other C₃HN species. The two anionic states interact with each other, and we study their electronic coupling by computing the two electron binding energies along one- and two-dimensional cuts through the potential energy surfaces, and fitting a diabatic model potential to the ab initio data. In particular, the two-dimensional cuts allow us to examine the geometry dependence of the electronic coupling, and to ask the question whether the coupling elements inferred from one-dimensional cuts represent typical values. Moreover, the influence of the theoretical method on the computed coupling elements is investigated, and the possibility of employing the diabatic model potential as a mean to extrapolate bound state binding energies into the metastable domain is pointed out.     

AunCu ( n =1-3)二元合金小团簇结构和稳定性的密度泛函研究

采用密度泛函理论(DFT) B3LYP 在SDD基组水平上对AunCu(n =1-3)二元合金小团簇各种可能的构型进行几何优化,预测了各团簇的稳定结构. 并对基态结构进行了研究,计算了平均结合能、最高占据轨道能级和最低空轨道能级以及两者间的能隙.结果表明掺杂Cu原子后使得AunCu(n =1-3)团簇的化学性质更稳定.     

Au_nCu(n=1～3)二元合金小团簇结构和稳定性的密度泛函研究

采用密度泛函理论(DFT)B3LYP在SDD基组水平上对Au_nCu(n=1～3)二元合金小团簇各种可能的构型进行几何优化,预测了各团簇的稳定结构.并对基态结构进行了研究,计算了平均结合能、最高占据轨道能级和最低空轨道能级以及两者间的能隙.结果表明掺杂Cu原子后使得Au_nCu(n=1～3)团簇的化学性质更稳定.     

Charge resonance enhanced ionization of CO2 probed by laser Coulomb explosion imaging

The process by which a molecule in an intense laser field ionizes more efficiently as its bond length increases towards a critical distance R(c) is known as charge resonance enhanced ionization (CREI). We make a series of measurements of this process for CO(2), by varying pulse duration from 7 to 200 fs, in order to identify the charge states and time scales involved. We find that for the 4+ and higher charge states, 100 fs is the time scale required to reach the critical geometry ≈ 2.1 ? and <θ(OCO)> ≈ 163° (equilibrium CO(2) geometry is ≈ 1.16 ? and <θ(OCO)> ≈ 172°). The CO(2)(3+) molecule, however, appears always to begin dissociation from closer than 1.7 ? indicating that dynamics on charge states lower than 3+ is not sufficient to initiate CREI. Finally, we make quantum ab initio calculations of ionization rates for CO(2) and identify the electronic states responsible for CREI.