碱金属掺杂叔丁基杯[4]芳烃体系的结构及非线性光学性质

采用密度泛函理论B3LYP方法得到了M@t-Bu-calix[4]arene和（M@t-Bu-calix[4]arene）Li'（M=Li,Na,K）体系的几何结构. 其中（M@t-Bu-calix[4]arene）Li'（M=Li,Na,K）三个体系各有5个稳定异构体,在前三个异构体中,碱金属与t-Bu-calix[4]arene分子间具有很强的相互作用能,说明了体系的稳定性. 在部分（M@t-Bucalix[4]arene）Li异构体中Li'原子以阴离子形式存在,整个体系表现出碱金属化物的特性. 此外,使用CAMB3LYP方法计算了t-Bu-calix[4]arene及碱金属掺杂后体系的非线性光学性质. 结果表明,t-Bu-calix[4]arene内部掺杂一个碱金属原子M后,体系的一阶超极化率（β₀）有较大提高,而在配体外部又掺杂一个Li原子后,体系具有更大的β₀值. 其中（M@t-Bu-calix[4]arene）Li'体系的MLi'-4异构体表现出最高的β₀值（41827-114354 a.u.）,并且随着M原子序数的增加而逐渐增大. 可见,碱金属掺杂是提高t-Bu-calix[4]arene非线性光学响应的一种有效策略.     

碱金属掺杂叔丁基杯[4]芳烃体系的结构及非线性光学性质

采用密度泛函理论B3LYP方法得到了M@t-Bu-calix[4]arene和(M@t-Bu-calix[4]arene)Li′(M=Li,Na,K)体系的几何结构.其中(M@t-Bu-calix[4]arene)Li′(M=Li,Na,K)三个体系各有5个稳定异构体,在前三个异构体中,碱金属与t-Bu-calix[4]arene分子间具有很强的相互作用能,说明了体系的稳定性.在部分(M@t-Bucalix[4]arene)Li异构体中Li′原子以阴离子形式存在,整个体系表现出碱金属化物的特性.此外,使用CAMB3LYP方法计算了t-Bu-calix[4]arene及碱金属掺杂后体系的非线性光学性质.结果表明,t-Bu-calix[4]arene内部掺杂一个碱金属原子M后,体系的一阶超极化率(β0)有较大提高,而在配体外部又掺杂一个Li原子后,体系具有更大的β0值.其中(M@t-Bu-calix[4]arene)Li′体系的MLi′-4异构体表现出最高的β0值(41827-114354 a.u.),并且随着M原子序数的增加而逐渐增大.可见,碱金属掺杂是提高t-Bu-calix[4]arene非线性光学响应的一种有效策略.     

锂掺杂胺化物中氮原子配位数效应对结构和非线性光学性质的影响

采用MP2／6—311＋＋G（d,p）方法得到了含有不同氮原子配位数的系列锂掺杂胺化物的几何结构,并使用MP2／6．311＋＋G（2d,p）方法计算了该系列的非线性光学性质．结果表明：相对于未掺杂体系,锂掺杂极大地增加了体系的一阶超极化率（β0）,其中1的β0值是掺杂前的3238倍;体系的风随着氮原子配位数的增加而显著增加,具有3个配位氮原子的1的风值达到2．8×10^5a．u．另外,频率依赖的一阶超极化率（β（-ω;ω,0）和β（-2ω;ω,0））也表现了同样的趋势．     

H3+nPMo12-nVnO40(n=0,1)掺杂聚苯胺功能材料新的 制备方法及性质

本文用一种新的合成方法,即不用其他质子酸和氧化剂,利用H3PMo12O40·nH2O和H4PMo11VO40·nH2O杂多酸独特的性质—集质子酸和氧化性于一身,将HPA直接与苯胺作用,制备了仅以杂多阴离子为唯一掺杂抗衡离子的PANI/HPA掺杂材料。所合成的材料具有导电性和荧光性。     

碱金属化物M+@H6Aza222M'-·2MeNH2(M,M'=Li,Na,K)一阶超极化率的理论研究

采用B3LYP/6-31G方法优化得到具有有机笼状配体的碱金属化物M+@H6 Aza222M'- ·2MeNH2(M, M'=Li,Na,K)的9个实频结构, 并发现配体内部的碱金属原子M的位置随其原子序数的逐渐减小而具有偏向笼状配体一侧的趋势. 在优化的结构基础上, 使用BHandHLYP方法计算了该体系的非线性光学性质. 结果表明, 该体系具有很大的一阶超极化率(β0), 其中Na+@H6Aza222K-·2MeNH2 的一阶超极化率高达1280342 a.u., 且体系的β0值随着配体外部的碱金属M'的原子序数的增大呈单调递增趋势.     

碱金属化物M+aza222M′- (M,M′=Li,Na, K)的结构及非线性光学性质

采用密度泛函理论(DFT)B3LYP方法得到具有有机穴状配体的碱金属化物M+aza222M′-(M,M′=Li,Na,K)的几何结构.并使用了BHandHLYP方法计算了此体系的非线性光学(NLO)性质.结果表明:该体系具有很大的一阶超极化率(β0),对于Li+aza222K-体系,β0值达到1.0×106a.u.;体系的β0值及配体aza222内外的碱金属之间距离与碱金属的原子序数均存在着依赖关系.通过与其它碱金属化物的β0值对比发现,aza222配体能够显著增大碱金属化物的一阶超极化率.     

超价化合物F_nLi_(n+1)(n=1～3)一阶超极化率的理论研究

采用UMP2/6-311+G(3df)方法得到了FnLin+1(n=1～3)体系的8个全部实频的异构体构型,并研究了这些体系的非线性光学性质.结果表明,这类超价化合物具有较大的一阶超极化率值(β0=2299.2～12322.3a.u.).超价化合物中弥散的电子云使体系具有较低的跃迁能,从而决定了FnLin+1具有较大的一阶超极化率.提示非中心对称的超价化合物将是一类潜在的非线性光学分子.     

TinC2n(n=1-6)分子簇的量子化学从头算研究

用量子化学从头计算方法研究了TinC2n(n=1-6)分子簇的几何构型和电子结构。这些TinC2n分子簇以TiC2为结构单元, 通过C-C或Ti-C键进一步连接而逐渐长大。研究结果可以较好地解释实验现象, 并说明Metcars的形成机理。     

H3+nPM012-nVnO40(n=0,1)掺杂聚苯胺功能材料新的制备方法及性质

传统的聚苯胺/杂多酸(PANI/HPA)掺杂材料的化学制备方法是一步法和二步法[1].这两种方法由于使用了质子酸(如HCl)和氧化剂[如(NH4)2S2O8],不可避免地在材料中引入了与杂多阴离子竞争的抗衡阴离子(如Cl-,SO42-),使得掺杂材料的组成复杂,功能性能受到影响.本文用一种新的合成方法,即不用其他质子酸和氧化剂,利用H3PMo12O40@nH2O和H4PMo11VO40@nH2O杂多酸独特的性质--集质子酸和氧化性于一身,将HPA直接与苯胺作用,制备了仅以杂多阴离子为唯一掺杂抗衡离子的PANI/HPA掺杂材料.所合成的材料具有导电性和荧光性.     

二硫蒽及其自由基正离子间电子转移反应的~1H/~2H和~(32)S/~(33)S同位素效应

二硫蒽和全氘代二硫蒽与它们的自由基正离子高氯酸盐之间的电子转移反应表现出显著的~1H/~2H和~(32)S/~(33)S同位素效应,可作为一种新的高效分离同位素方法的基础。     

Linear and nonlinear feature of electronic excitation energy in carbon chains HC2n+1H and HC2nH

Density functional theory has been used to investigate the geometries, bonding, and vibrational frequencies of HC_2nH (n = 1–13) and HC_2n+1H (n = 2–12). Vertical excitation energies for the X¹Σ → 1¹Σ transition of HC_2nH (n = 1–5) and for the X³Σ → 1³Σ transition of HC_2n+1H (n = 2–5) have been calculated by the time‐dependent density functional theory and ab initio second‐order multiconfiguration perturbation method, respectively. On the basis of the present calculations, explicit expressions for the size dependence of excitation energy in linear polyynes HC_2n+1H and HC_2n+1H are suggested. Such analytical λ ? n relationships show good agreement with experimental observations. Theoretical investigations of relevant excited states demonstrate that distinct linear and nonlinear spectroscopic features in such polyynes can be ascribed to similarity and difference in bonding between the ground and excited states in HC_2n+1H and HC_2nH. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

叠氮化合物C6H6-n(N3)n(n=1~6)的密度泛函理论研究

运用密度泛函理论, 在B3LYP/6-31G*水平上, 对叠氮化合物C6H6-n(N3)n(n=1~6)进行理论计算, 并对所得到的几何结构进行了振动频率分析. 计算结果表明, 这些化合物是热力学稳定的. 基于自然键轨道理论, 分析了稳定结构的电荷分布及成键情况. 在不破坏苯环和叠氮基的原则下, 设计等键反应计算了这些化合物的生成热, 结果表明, 标题化合物的生成热都很高, 且随着叠氮基数目的增加而线性增大.     

Infrared spectra of HC2-.(C2H2)n and O2-.(C2H2)n clusters (n=2-5)

We study the solvation of HC2- and O2- with acetylene ligands by means of midinfrared photodissociation spectroscopy in the CH stretching region, monitoring C2H2 evaporation upon infrared photon absorption by the parent cluster ions. Our findings are interpreted with the help of density functional theory. The infrared spectra indicate that while the binding generally occurs through ionic H bonds, there are two different classes of ligands which differ in their binding strength. This holds true for both core ions, even though their electronic structures and charge distributions are very different.     

Odd carbon long linear chains HC2n+1H (n = 4-11): properties of the neutrals and radical anions

The optimized geometries, adiabatic electron affinities, vertical electron affinities, vertical electron detachment energies (for the anions), and IR-active vibrational frequencies have been predicted for the long linear carbon chains HC(2)(n)()(+1)H (n = 4-11). The B3LYP density functional combined with DZP and TZ2P basis sets was used in this theoretical study. These methods have been extensively calibrated versus experiment for the prediction of electron affinities (Chem. Rev. 2002, 102, 231). The computed physical properties are discussed and compared with the even carbon chains HC(2)(n)()H. The predicted electron affinities form a remarkably regular sequence: 2.12 eV (HC(9)H), 2.42 eV (HC(11)H), 2.66 eV (HC(13)H), 2.85 eV (HC(15)H), 3.01 eV (HC(17)H), 3.14 eV (HC(19)H), 3.25 eV (HC(21)H), and 3.35 eV (HC(23)H). These electron affinities are as much as 0.4 eV higher than those for analogous even carbon chains. The predicted structures display an intermediate cumulene-polyacetylene type of bonding, with the inner carbons appearing cumulenic and the outer carbons polyacetylenic.     

Structural and Spectroscopic Properties of Linear Carbon Chains NC2nN and HC2n+1N (n = 1～10)

Using density functional theory, geometries and vibrational frequencies of linear chains NC2nN and HC2n+1N (n = 1～ 10) have been investigated.Time-dependent density functional theory (TD-DFT) has been used to calculate the vertical transition energies and oscillator strengths for the X 1∑+k → 11∑+u transition in NC2nN (n = 1 ～10) and X1∑+ → 11∑+ transition in HC2n+1N (n =1 ～7).On the basis of present calculations, the explicit expressions for the size dependence of the excitation energy and the first adiabatic ionization energy in both carbon chains have been suggested.     

Infrared spectra of the Li+-(H2)n (n=1-3) cation complexes

The Li+-(H2)n n=1-3 complexes are investigated through infrared spectra recorded in the H-H stretch region (3980-4120 cm-1) and through ab initio calculations at the MP2/aug-cc-pVQZ level. The rotationally resolved H-H stretch band of Li+-H2 is centered at 4053.4 cm-1 [a -108 cm-1 shift from the Q1(0) transition of H2]. The spectrum exhibits rotational substructure consistent with the complex possessing a T-shaped equilibrium geometry, with the Li+ ion attached to a slightly perturbed H2 molecule. Around 100 rovibrational transitions belonging to parallel Ka=0-0, 1-1, 2-2, and 3-3 subbands are observed. The Ka=0-0 and 1-1 transitions are fitted by a Watson A-reduced Hamiltonian yielding effective molecular parameters. The vibrationally averaged intermolecular separation in the ground vibrational state is estimated as 2.056 A increasing by 0.004 A when the H2 subunit is vibrationally excited. The spectroscopic data are compared to results from rovibrational calculations using recent three dimensional Li+-H2 potential energy surfaces [Martinazzo et al., J. Chem. Phys. 119, 11241 (2003); Kraemer and Spirko, Chem. Phys. 330, 190 (2006)]. The H-H stretch band of Li+-(H2)2, which is centered at 4055.5 cm-1 also exhibits resolved rovibrational structure. The spectroscopic data along with ab initio calculations support a H2-Li+-H2 geometry, in which the two H2 molecules are disposed on opposite sides of the central Li+ ion. The two equivalent Li+...H2 bonds have approximately the same length as the intermolecular bond in Li+-H2. The Li+-(H2)3 cluster is predicted to possess a trigonal structure in which a central Li+ ion is surrounded by three equivalent H2 molecules. Its infrared spectrum features a broad unresolved band centered at 4060 cm-1.     

Ab initio characterization of size dependence of electronic spectra for linear anionic carbon clusters C(n) (-) (n = 4-17)

In this article, we determine the ground‐state equilibrium geometries of the linear anionic carbon clusters C (n = 4–17) by means of the density functional theory B3LYP, CAM‐B3LYP, and coupled cluster CCSD(T) calculations, as well as their electronic spectra obtained by the multireference second‐order perturbation theory CASPT2 method. These studies indicate that these linear anions possess doublet ²∏_g or ²∏_u ground state, and the even‐numbered clusters are generally acetylenic, whereas the odd‐numbered ones are essentially cumulenic. The energy differences, electron affinities, and incremental binding energies of C chains all exhibit a notable tread of parity alternation, with n‐even chains being more stable than n‐odd ones. In addition, the predicted vertical excitation energies from the ground state to four low‐lying excited states are in reasonably good agreement with the available experimental observations, and the calculations for the higher excited electronic transitions can provide accurate information for the experimentalists and spectroscopists. Interestingly, the absorption wavelengths of the 1²∏_u/g ← X²∏_g/u transitions of the n‐even clusters show a nonlinear trend of exponential growth, whereas those of the n‐odd counterparts are found to obey a linear relationship as a function of the chain size, as shown experimentally. Moreover, the absorption wavelengths of the transitions to the higher excited states of C series have the similar linear size dependence as well. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

Threshold photoionization and density functional theory studies of the niobium carbide clusters Nb3C(n) (n = 1-4) and Nb4C(n) (n = 1-6)

We have used photoionization efficiency spectroscopy to determine ionization potentials (IP) of the niobium-carbide clusters, Nb3C(n) (n = 1-4) and Nb4C(n) (n = 1-6). The Nb3C2 and Nb4C4 clusters exhibit the lowest IPs for the two series, respectively. For clusters containing up to four carbon atoms, excellent agreement is found with relative IPs calculated using density functional theory. The lowest energy isomers are mostly consistent with the development of a 2 x 2 x 2 face-centered cubic structure of Nb4C4. However, for Nb3C4 a low-lying isomer containing a molecular C2 unit is assigned to the experimental IP rather than the depleted 2 x 2 x 2 nanocrystal isomer. For Nb4C5 and Nb4C6, interpretation is less straightforward, but results indicate isomers containing molecular C2 units are the lowest in energy, suggesting that carbon-carbon bonding is preferred when the number of carbon atoms exceeds the number of metal atoms. A double IP onset is observed for Nb4C3, which is attributed to ionization from the both the lowest energy singlet state and a meta-stable triplet state. This work further supports the notion that IPs can be used as a reliable validation for the geometries of metal-carbide clusters calculated by theory.     

Dependence on Oil Chain Length of the Curvature Elastic Properties of Nonionic Surfactant Films: Emulsification Failure and Phase Equilibria

We compare two ternary microemulsions, stabilized by the nonionic surfactant pentaethylene‐glycol‐dodecyl‐ether (C₁₂E₅), containing decane or hexadecane. The comparison involves phase behavior and properties of O/W droplet microemulsions investigated with SAXS, static and dynamic light scattering, and NMR. Striking differences are observed. The systems are analyzed in terms of curvature elastic properties of surfactant film. Apart from an increase of the spontaneous curvature, there also appears to be a small but significant increase in the saddle splay constant as the oil chain length is increased.