从一道习题解答谈水的Λm和Λ∞m

电解质的摩尔电导率Λm是指把含有1mol电解质的溶液置于相距单位距离的电导池的两个平行电极之间时具有的电导.摩尔电导率受溶液的浓度影响,不管是强电解质还是弱电解质,随着溶液浓度的减小,摩尔电导率增大.Λ∞m就是指溶液无限稀释时的摩尔电导率.这里的溶液是用水作溶剂,那对于纯水的Λm和Λ∞m又作何理解呢?下面以一道常见的习题的解答来谈谈笔者的看法,权作引玉之砖.该习题出自南京大学傅献彩等编的<物理化学>(下册)第5版第57页(习题18)[1].     

一种Λ型吡啶碘盐的合成和晶体结构

近年来光纤通讯、激光二极管、光信号处理及光计算等领域的快速发展极大地推动了非线性光学的研究[1-3].新型非线性光学材料的设计及合成是该领域人们关注的热点之一[1,4,5].     

一种Λ型吡啶碘盐的合成和晶体结构

A new Λ type pyriding iodide was synthesized by reaction of 4-picoline and methyl diiodide. The structure was characterized by elemental analysis, IR, UV and TG. The crystal structure of the title compound was determined by X-ray single crystal diffraction. The crystal belongs to monoclinic with space group C2/c, a=18.812(4)?, b=8.7816(6)?, c=10.3165(12)?, β=93.71(1), V=1700.7(4)?³, Z=4. In the molecule, two 4-picoline molecules are bonded by -CH₂ group to form Λ type pyridine salt. CCDC: 180871.     

Π态双原子分子Λ分裂引起的量子干涉

To interpret theoretically the abnormal phenomenon in the experiment of collision-induced rotational energy transfer of CO（A1Π,v=3）with He by Sun et al.,the time dependent first order Born approximation,and the long-range interaction potentials and“straight-line”trajectory approximation are taken into account. A theoretical model of quantum interference of Π-state diatomic molecules,which originates from the difference between the two "Λ-related collision potential energy surface,is presented. The abnormal phenomenon of σε→ε'ΔJ=0<σε→ε'ΔJ=±1 for He is also interpreted successfully. At first the theoretical development of collision-induced quantum interference on rotational energy transfer is reported;then a theoretical model of quantum interference of Π-state diatomic molecules,which originates from the difference between the two "Λ-related collision potential energy surfaces,is presented;in the end the results have been discussed and concluded.     

VIER- UND FÜNFGLIEDRIGE PHOSPHORHETEROCYCLEN,XVI 1.3.4.2Λ3-OXADIAZAPHOSPHOLINE

Abstract

Die Kondensation von N ¹-substituierten N-Acetyl-und-Benzoyl-hydrazinen mit P[N(CH₃)₂]₃ oder CH₃P[NCH₃)₂]₂ fuhrt stets zu 3-substituierten 1.3.4.2Λ³-Oxadizaphospholinen, auch wenn der jeweilige Substituent die Bildung von anderen isomeren Fünfringen oder von Isomeren mit größerem Ring oder eine weitergehende Kondensation zuließe. Sie können in die 2.2-Dichloro- und 2-Thioxo-1.3.4.2Λ⁵-Oxadiazaphospholine übergeführt werden.

Condensation of N ¹-substituted N-acetyl and N-benzoyl hydrazines with P[N(CH₃)₂]₃ or CH₃P[N(CH₃)₂] 2 always gives 3-substituted 1.3.4.2Λ3-oxadiazaphospholines, even if the substituent would allow other isomeric five membered or larger ring phosphorus heterocycles to be formed, or the condensation to proceed further. The title compounds can be oxidized to 2.2-dichloro and 2-thioxo 1.3.4.2Λ⁵-oxadiazaphospholines.     

分子振动力常数计算中的Λ矩阵和F矩阵的性质

在由G矩阵因解和频率确定力常数的计算中,找到了适用于任意维A矩阵相对于L矩阵按对称坐标排列顺序的关系;用逆酉变换得到了由复合力常数F_s计算F_R的一般方法;确立了F_R按对称块的加和性。以尿素等分子为例,用一般价力场计算了全部力常数F_R,频率计算值(低频部分)更符合实验结果。     

聚集态荧光增强的Λ-型异弗乐酮衍生物纳米粒子

本文选择Λ-型TB骨架作为分子的基本框架, 将二腈基异弗乐酮引入其中, 采用简便方法合成了一种具有聚集态荧光增强现象的红光材料2,8-双[2-(5,5-二甲基-环乙烯基-2-烯基)丙二腈]-6H,12H-5,11-甲基二苯[b,f][1,5]二氮芳辛(DMCEM). 同时, 制备了粒径不同的DMCEM纳米颗粒, 并对其光学性质进行了研究.     

The role of polar, lamdba (Λ)-shaped building units in noncentrosymmetric inorganic structures

A methodology for the design of polar, inorganic structures is demonstrated here with the packing of lambda (Λ)-shaped basic building units (BBUs). Noncentrosymmetric (NCS) solids with interesting physical properties can be created with BBUs that lack an inversion center and are likely to pack into a polar configuration; previous methods to construct these solids have used NCS octahedra as BBUs. Using this methodology to synthesize NCS solids, one must increase the coordination of the NCS octahedra with maintenance of the noncentrosymmetry of the bulk. The first step in this progression from an NCS octahedron to an inorganic NCS solid is the formation of a bimetallic BBU. This step is exemplified with the compound CuVOF(4)(H(2)O)(7): this compound, presented here, crystallizes in an NCS structure with ordered, isolated [Cu(H(2)O)(5)](2+) cations and [VOF(4)(H(2)O)](2-) anions into Λ-shaped, bimetallic BBUs to form CuVOF(4)(H(2)O)(6)·H(2)O, owing to the Jahn-Teller distortion of Cu(2+). Conversely, the centrosymmetric heterotypes with the same formula MVOF(4)(H(2)O)(7) (M(II) = Co, Ni, and Zn) exhibit ordered, isolated [VOF(4)(H(2)O)](2-) and [M(H(2)O)(6)](2+) ionic species in a hydrogen bond network. CuVOF(4)(H(2)O)(7) exhibits a net polar moment while the heterotypes do not; this demonstrates that Λ-shaped BBUs give a greater probability for and, in this case, lead to NCS structures.     

六元碳环邻位对称取代的Λ-型分子非线性光学系数的计算

采用密度泛函理论(DFT)的BHandHLYP/6-31G*方法,对3类含有六元碳环的Λ-型分子的几何构型进行优化.在优化结构的基础上,结合有限场方法(FF)和含时密度泛函理论(TD-DFT)对分子的二阶非线性光学(NLO)活性及电子吸收光谱进行研究.结果表明,在拐点处环己烷的构象不同时,分子电荷分布、偶极矩、极化率、二阶NLO系数和电子吸收光谱等变化很小.以苯环为拐点片段的分子有所不同,当支链取代基R增大时,以苯环为拐点片段分子的极化率和二阶NLO系数增加明显.     

1~Π态双原子分子中关于Λ量子干涉的微分干涉角(英文)

Sha等在静态池实验中观察到了转动能量转移中的碰撞量子干涉,并且计算了决定跃迁散射截面的积分干涉角(J.Chem.Phys.,1995,102:2772).由于积分干涉角是微分干涉角的平均效应,为了得到更精确的信息,进行了分子束实验.作者文运用含时微扰的一级波恩近似理论,提出了衡量干涉程度的1П态双原子分子中关于Λ量子干涉的微分干涉角.利用各向异性相互作用势计算了其干涉角.得到分子束实验中微分干涉角随实验参数,包括实验温度、碰撞伴、作用距离和转动量子数变化的关系.并且讨论了影响干涉角的各种参数.此理论模型对理解和进行分子束实验是非常重要的.     

Synthesis of a β-glycoside functionalized GΛC motif for self-assembly into rosette nanotubes with predefined length

Progress toward the synthesis of guanine-cytosine (GΛC) oligonucleotides for the spontaneous self-assembly of rosette nanotubes (RNTs) with predefined length is described. Highlighted is the synthesis of the β-glycoside functionalized GΛC base along with a new nitrogen protecting group strategy that is compatible with Boc and Bn groups.     

△,Λ-[Co(phen)2tpphz]3+与B-DNA相互作用的分子模拟

针对国际上对金属配合物同DNA间作用机量的争议,采用分子模拟手段在MM2力场下,搭建并优化了手性金属配合物△,Λ-[Co(phen)2tpphz]^3+与B-DNA[d(GTCGATCGAC)2]的模型,继而对其相互作用进行了模拟,得出的结论是：对所采用的B-DNA片断,该金属配合物有明显的立体选择性△型配合物从小沟插入占明显优势,而且,总体来看,从AT区插入更易进行。     

△,Λ-[Co(phen)2tpphz]^3+与B - DNA相互作用的分子 模拟

针对国际上对金属配合物同DNA间作用机量的争议,采用分子模拟手段在MM2力场下,搭建并优化了手性金属配合物△,Λ-[Co(phen)2tpphz]^3+与B-DNA[d(GTCGATCGAC)2]的模型,继而对其相互作用进行了模拟,得出的结论是：对所采用的B-DNA片断,该金属配合物有明显的立体选择性△型配合物从小沟插入占明显优势,而且,总体来看,从AT区插入更易进行。     

Λ-及Δ-[Ru(phen)2dppz]n+对错配DNA的识别作用的分子模拟

本文通过在ESFF(Extensible Systematic Force Field)力场下对其作用中的体系势能进行分子力学计算，分析了手性金属配合物Λ－及Δ-[Ru(phen)2dppz]^n 对错配DNA d(CCGAATGAGG)2的识别机理，并在分子水平上对其做了详细解释。     

分子模拟手性金属配合物△,Λ-[Co(phen)_2dppz]~(3 )与B-DNA的作用模型

利用分子模拟方法, 通过研究手性金属配合物[Co(phen)2dppz]3 (phen = 1, 10-phenanthroline, dppz = dipyrido[3, 2-a: 2′, 3′-c]phenazine)与B-DNA的作用机理, 探讨了当前存在争议的两种模型: 即Barton的从DNA大沟插入、且 D 型异构体更易于和B-DNA结合的模型和Norden的从DNA小沟插入、且没有显著异构体选择性的模型.最终, 研究结果支持Norden的结合模型, 而对Barton的结合模型提出了异议.     

Λ-、Δ-[Rh(bpy)2chrysi]3+对含C:T错配的DNA序列识别作用的分子模拟研究

通过分子模拟方法研究了手性金属配合物[Rh(bpy)2Chrysi]3 (bpy=2,2’- bipyridine;Chrysi=5,6-chrysenequinonediimine)对包含C:T错配碱基对的B-DNA序列的识别作用。结合类似的针对含G:A错配的和正常的B-DNA序列的识别作用研究,发现配合物[Rh(bpy)2Chrysi]3 可以对错配B-DNA序列进行序列特异性的识别．能量对比计算结果表明,该经典插入识别作用倾向于在错配碱基对附近进行,其中Δ-[Rh(bpy)2charysi]3 比其手性异构体更占优势．这同Barton教授工作组的实验结果是一致的。另外插入作用倾向于在错配序列中的正常双碱基对C3A4／G374(错配碱基对附近)中从小沟进行．与该配合物对含G:A错配的和正常的B-DNA序列的识别作用不同的是,对包含C:T错配碱基对的B-DNA序列的识别作用倾向于从小沟进行．这一点可能源于C:T碱基对结构的不同．     

Symmetric and asymmetric triple excitation corrections for the orbital-optimized coupled-cluster doubles method: improving upon CCSD(T) and CCSD(T)(Λ): preliminary application

Symmetric and asymmetric triple excitation corrections for the orbital-optimized coupled-cluster doubles (OO-CCD or simply "OD" for short) method are investigated. The conventional symmetric and asymmetric perturbative triples corrections [(T) and (T)(Λ)] are implemented, the latter one for the first time. Additionally, two new triples corrections, denoted as OD(Λ) and OD(Λ)(T), are introduced. We applied the new methods to potential energy surfaces of the BH, HF, C(2), N(2), and CH(4) molecules, and compare the errors in total energies, with respect to full configuration interaction, with those from the standard coupled-cluster singles and doubles (CCSD), with perturbative triples [CCSD(T)], and asymmetric triples correction (CCSD(T)(Λ)) methods. The CCSD(T) method fails badly at stretched geometries, the corresponding nonparallelity error is 7-281 kcal mol(-1), although it gives reliable results near equilibrium geometries. The new symmetric triples correction, CCSD(Λ), noticeably improves upon CCSD(T) (by 4-14 kcal mol(-1)) for BH, HF, and CH(4); however, its performance is worse than CCSD(T) (by 1.6-4.2 kcal mol(-1)) for C(2) and N(2). The asymmetric triples corrections, CCSD(T)(Λ) and CCSD(Λ)(T), perform remarkably better than CCSD(T) (by 5-18 kcal mol(-1)) for the BH, HF, and CH(4) molecules, while for C(2) and N(2) their results are similar to those of CCSD(T). Although the performance of CCSD and OD is similar, the situation is significantly different in the case of triples corrections, especially at stretched geometries. The OD(T) method improves upon CCSD(T) by 1-279 kcal mol(-1). The new symmetric triples correction, OD(Λ), enhances the OD(T) results (by 0.01-2.0 kcal mol(-1)) for BH, HF, and CH(4); however, its performance is worse than OD(T) (by 1.9-2.3 kcal mol(-1)) for C(2) and N(2). The asymmetric triples corrections, OD(T)(Λ) and OD(Λ)(T), perform better than OD(T) (by 2.0-6.2 kcal mol(-1)). The latter method is slightly better for the BH, HF, and CH(4) molecules. However, for C(2) and N(2) the new results are similar to those of OD(T). For the BH, HF, and CH(4) molecules, OD(Λ)(T) provides the best potential energy curves among the considered methods, while for C(2) and N(2) the OD(T) method prevails. Hence, for single-bond breaking the OD(Λ)(T) method appears to be superior, whereas for multiple-bond breaking the OD(T) method is better.     

Δ-和Λ-[Ru(bpy)2(HPIP)2+两种异构体对小牛胸腺DNA不同键合速率的CD光谱证明

Wilson[1]于1997年发表了关于DNA导电性的评论性文章, 介绍了各种学派的观点. 争论焦点在于DNA是否为导体. 将两种配合物键合于DNA作为接头, 通过研究电子转移可确定DNA是否为导线, 其中配合物和DNA键合模式是研究的关键. Barton[2]和Norden[3]均认为2+ 配合物能强烈插入DNA中. 我们[4]曾从改变辅助配体角度出发, 研究2+和DNA的作用, 结果证明2+具有更强的插入能力, 并结合文献把键合模式归纳为3类, 即静电键合、沟面键合和插入键合[5]. 最近, 我们报道了新体系2+/DNA/2+(bpy=2,2′-bipyridine), 其中2+和2+均可插入DNA中. 2+是光诱导电子给予体, 2+是电子接受体, 荧光光谱证明前者的电子通过DNA中的π电子转移给后者, 导致后者荧光猝灭, 结果支持DNA是导线的观点[6]. 2+中的PIP芳香环和DNA碱基芳环组成π电子的堆积力[7], 从而增强了对DNA的插入能力.     

Λ-、△-[Rh（bpy）2chrysi]^3＋对含C：T错配的DNA序列识别作用的分子模拟研究

通过分子模拟方法研究了手性金属配合物[Rh（bpy）2Chrysi]^3＋（bpy=2，2’-bipyridineChrysi=5，6-chrysenequinonediimine）对包含C：T错配碱基对的B-DNA序列的识别作用．结合类似的针对含G：A错配的和正常的B-DNA序列的识别作用研究，发现配合物I-Rh（bpy）zChrysi]^3＋可以对错配B-DNA序列进行序列特异性的识别．能量对比计算结果表明，该经典插入识别作用倾向于在错配碱基对附近进行，其中△-[Rh（bpy）2chrysi]^3＋比其手性异构体更占优势．这同Barton教授工作组的实验结果是一致的．另外插入作用倾向于在错配序列中的正常双碱基对C3A4／G3T4（错配碱基对附近）中从小沟进行．与该配合物对含G：A错配的和正常的B-DNA序列的识别作用不同的是，对包含C：T错配碱基对的B-DNA序列的识别作用倾向于从小沟进行．这一点可能源于C：T碱基对结构的不同．