含钼和钨的长链聚合物菲线性光学性质的从头算研究

用RHF／Lanl2DZ及扩展基组计算了含金属铝和钨的一维长链聚合物[N（M（OR）3]n（M=Mo,R=CMe3,CMe2CF3;M=W,R=CMe3）的一阶超极化率。在短链时,钼聚合物的超极化率大于相应的钨聚合物,在长链时,铝聚合物的超极化率小于相应的钨聚合物。而三氟甲基取代的铝聚合物的超极化率大于甲基取代的钼聚合物。我们发现,在选取简化模型来计算非线性光学性质时,不能单纯考虑能量最优构型,还要考虑到与原体系在成键结构,特别是在电荷分布方面的相似性。例如本文中,若按量子化学计算惯例,将甲基CH3用H原子代替,氟代甲基CF3用F原子代替,优化的简化模型的电荷分布与真实分子的电荷分布明显不同。本文还讨论了含重金属一维长链聚合物的量子化学研究中的基组的选择。     

端基取代的长链硅烷二阶超极化率的量子化学研究

对端基取代的一维无限长反位硅烷H₂N-(SiH₂-SiH₂)_n-NO₂的二阶超极化率进行了系统的量子化学研究. 通过仔细检验和选择外场强度, 采用9个外场强度(0.0000, ±0.0008, ±0.0012, ±0.0016, ±0.0020 a.u.)计算的体系能量来确定4阶场强展开式中的5个系数, 从而得到可靠的二阶超极化率. 建议数据拟合时用二阶超极化率单元值的平均值形式γ(n)/n作为拟合对象, 同时用1/n的2阶多项式作为拟合函数, 以得到无限长链的二阶超极化率极限值. 拟合数据范围的选择应该使该数据范围得到的极限值与其临近数据范围得到的极限值的均方偏差最小. 分子构型的优化使计算的二阶超极化率增加大约20%, 在基组中增加极化函数使二阶超极化率在无限长链时的极限值减少大约15%. 相关效应的影响最大, MP2的结果比RHF的结果增加近一倍. 根据本文最高水平MP2/6-31G(d)//RHF/6-31G的计算, 端基取代的一维无限长反位硅烷H₂N-(SiH₂-SiH₂)_n-NO₂的二阶超极化率的每单元极限值为0.8364×10⁶ a.u.     

14顶点双取代碳硼烷和金属硼烷极化率和二阶超极化率的DFT研究

采用量子化学密度泛函理论(DFT) B3LYP/6-31G(d)方法对14顶点双取代碳硼烷和金属硼烷几何构型进行优化, 结合有限场(FF)方法计算了各体系的极化率和二阶超极化率. 同时金属硼烷中金属原子采用赝势基组进行计算, 讨论基组对计算结果的影响. 结果表明, 14顶点碳硼烷和金属硼烷中碳和金属元素的成键方式不同, 金属硼烷中各原子间距离比碳硼烷中大, 平面偏移角增大. 金属原子的引入有效增加分子的NLO系数, 同时金属硼烷的前线分子轨道能级差比碳硼烷小很多, 金属硼烷材料有可能表现出半导体甚至导体特性, 金属原子采用不同基组对计算结果影响不大.     

具有Lindqvist结构的[Mo6O19]2-化合物及其二钨取代物的电子性质和稳定性的理论研究

采用密度泛函理论研究了具有Lindqvist结构的[Mo6O19]2-及其两个钨原子取代化合物的电子性质和稳定性, 计算得到的几何数据和实验值符合得很好. 从Mulliken电荷分布、键能大小以及轨道性质的分析可以得出结论, 当两个钨原子在邻位取代钼原子时所得到的取代产物([4,5-W2Mo4O19]2-)比当两个钨原子在对位取代钼原子时所得到的产物([4,6-W2Mo4O19]2-)更稳定, 而[4,5-W2Mo4O19]2-的反应活性比[4,6-W2Mo4O19]2-的大.     

双环金属铱(Ⅲ)异腈配合物的二阶非线性光学性质

采用密度泛函理论(DFT)方法对双环金属Ir(III)异腈配合物的非线性光学(NLO)性质进行计算研究。用B3PW91(UB3PW91)(金属原子采用LANL2DZ基组,非金属原子采用6-31G*基组)方法对配合物进行几何结构优化。在优化构型基础上,采用B3PW91(UB3PW91)和B3LYP(UB3LYP)方法计算了配合物的第一超极化率(βtot),并用CAM-B3LYP(UCAM-B3LYP)(金属原子采用LANL2DZ基组,非金属原子采用6-31G**基组)方法模拟配合物的吸收光谱。结果表明,主配体的取代基(R1)和副配体的取代基(R2)对第一超极化率值贡献不大。配合物发生氧化还原反应,电荷转移方式增多,电荷转移程度增大,使βtot值显著增加,其中1a+([(C∧N)2Ir(CNR)2]+(R=CH3))发生氧化反应和还原反应的βtot值分别增大了75倍和144倍。因此,这类双环金属铱(III)异腈配合物的氧化还原反应可以有效地调节其二阶NLO性质。     

二阶超极化率γ的Hartree-Fock极限值的再研究

用有限场(FF)方法,在ROHF/x-aug-cc-pVXZ(x=1～5或7,X=T,Q)水平上计算了C,N,O,F,OH和OH⁺等开壳层原子和分子、离子的二阶超极化率γ.与闭壳层原子和分子的计算结果相类似,γ随基组的增大出现一个拐点.拐点对应的γ值与数字轨道计算的γ值符合得较好,其平均相对误差分别为1.79%(x-aug-cc-pVTZ)和1.91%(x-aug-cc-pVQZ),故计算二阶超极化率γ不需使用g函数.进一步研究表明,用x-aug-cc-pVTZ系列基组不仅可以得到γ的Hartree-Fock极限值,而且可以用来作较准确的二阶超极化率相关效应的计算.     

Au的乙炔配合物非线性光学性质的量子化学计算

对过渡金属Au的有机配合物Ph3PAuC≡CR (R＝C6H4OCH3, Ph, C6H4NO2和PyNO2)的极化率和一阶、二阶超极化率进行了量子化学计算. 构型在B3LYP/CEP-121G水平优化. 用有效模型势方法和二阶多体微扰方法分别考虑了相对论效应和电子相关效应. 对基组进行了慎重的选择, 以ECP-HYPOL基组为对照标准, 在LFK基组基础上简化得到一个较小的基组LFK2. 计算结果与实测结果趋势一致.     

分子二阶超极化率γ的Hartree-Fock极限值

用共轭微扰Hartree-Fock (CPHF)方法,在RHF/x-aug-cc-pVXZ (x=0～8, X=T, Q)水平上计算了He, Ne, H₂, FH, CO和OH^-等原子和分子的二阶超极化率γ.发现当基组增大时,超极化率γ起初趋向于收敛,但当基组继续增大时,γ值又趋于发散,即γ随基组的增大出现一个拐点.拐点对应的γ值与数字轨道计算的γ值符合得较好.初步讨论认为γ值的发散是由于基组在近核区域的不完全性造成的.建议用拐点处的γ值作为Hartree-Fock极限值.     

过渡金属(Ni、Pd、Pt)配合物二阶超极化率的量子化学研究

对ⅧA族过渡金属有机配合物(trans-[Ni(C≡CPh)2(PEt3)2]、trans-[Pd(C≡CPh)2(PEt3)2]、trans-[Pt(C≡CPh)2(PEt3)2])的二阶超极化率进行了量子化学计算研究.分别使用Lanl2dz基组、CEP-31G和CEP-31+G基组,在MP2、HF、B3LYP水平上计算分子的二阶超极化率,各金属配合物的二阶超极化率(γ)的变化趋势为:trans-[Ni(C≡CPh)2(PEt3)2]相似文献   

卤原子取代苯并噻二唑聚合物给体材料的合成及其光伏性能研究

通过对苯并噻二唑单元进行氟、氯等卤原子取代,并同时调节烷基侧链的长度,设计合成了一系列基于苯并噻二唑四噻吩类的聚合物太阳电池材料.不同卤原子取代以及烷基侧链的长度都会影响聚合物的结晶性和薄膜聚集形貌从而改变其带隙和电荷传输性质.氟、氯原子的引入可调节聚合物的能级结构,而且相对于氟原子而言,具有更大原子半径的氯原子的引入可在更大尺度下调节能级结构,从而大幅提高相应太阳电池的开路电压,同时通过侧链的优化可进一步调节聚合物的微观聚集结构,改善器件能量转换效率.结果表明,在氯原子和氟原子共同作用的情况下,引入较长的侧链有利于提升聚合物的开路电压和短路电流,从而获得较好的器件性能.其中,以氯、氟共同取代的聚合物PCFBT4T-2OD与PC_(71)BM为活性层的器件性能最佳,能量转换效率可达8.84%.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.