阴离子主导的手性Cu(II)配位聚合物:可逆的结构转换,圆二色谱和二次谐波响应

用手性的V形双齿配体N，N''-（（1R，2R）-1，2-二取代环己二胺）双（N-苯甲酸（3-吡啶亚甲基）酰胺（1R，2R）-3-bcpb）和不同的Cu(II)盐反应，组装成2个新的手性Cu(II)配位聚合物{[Cu（（1R，2R）-3-bcpb）]Cl₂}_n（1）和{[Cu（（1R，2R）-3-bcpb）₂]（ClO₄）₂·2H₂O·2CH₃OH}_n（2）。其中1是一维链状结构，2具有二维（4，4）网络拓扑。溶剂热条件下，在甲醇溶剂体系中，通过引入AgClO₄，1能转换成2，同时通过加入NaCl，2也能转换成1。圆二色谱和二次谐波响应测试验证了它们具有结构上的手性。     

基于轴手性配体的两个镧系金属配合物的合成、表征及其荧光性质

通过水热法,合成了2个基于轴手性配体2,2''-dinitro-4,4''-biphenyldicarboxylic acid（H₂nbpdc）的配位聚合物[La（nbpdc）（phen）（FA）]_n（1）,[Eu（nbpdc）（phen）（FA）]_n（2）（phen=菲咯啉,FA=甲酸根）,并且对2个化合物进行了红外、单晶X射线衍射、热重、荧光、CD谱及介电性质的研究。晶体结构测试表明,2个化合物结晶在正交晶系P2₁2₁2₁手性空间群,且具有相同的三维拓扑结构。荧光性质测定表明化合物1和2分别在606和615.5 nm处有强的发射光谱。与此同时,固体CD谱测试进一步证实2个化合物具有手性。     

基于轴手性配体的两个镧系金属配合物的合成、表征及其荧光性质

通过水热法，合成了2个基于轴手性配体2，2''-dinitro-4，4''-biphenyldicarboxylic acid（H₂nbpdc）的配位聚合物[La（nbpdc）（phen）（FA）]_n（1），[Eu（nbpdc）（phen）（FA）]_n（2）（phen=菲咯啉，FA=甲酸根），并且对2个化合物进行了红外、单晶X射线衍射、热重、荧光、CD谱及介电性质的研究。晶体结构测试表明，2个化合物结晶在正交晶系P2₁2₁2₁手性空间群，且具有相同的三维拓扑结构。荧光性质测定表明化合物1和2分别在606和 615.5 nm处有强的发射光谱。与此同时，固体CD谱测试进一步证实2个化合物具有手性。     

手性化合物[Co(L/D-thr)3]·4.5H2O的合成、结构以及圆二色性

合成了2个基于手性配体L-和D-苏氨酸（L/D-thr）的Co（III）配合物的对应异构体[Co（L-thr）₃]·4.5H₂O（L-1）和[Co（L-thr）₃]·4.5H₂O（D-1）,并对2个化合物进行了单晶X射线衍射、红外、热重、紫外可见光谱以及CD谱性质研究。晶体结构分析表明,2个化合物分别结晶在四方晶系P4₃2₁2和P4₁2₁2手性空间群。固体CD谱测试进一步证实2个化合物具有手性。     

手性化合物[Co（L/D-thr）3]·4.5H2O的合成、结构以及圆二色性

合成了2个基于手性配体L-和D-苏氨酸（L/D-thr）的Co（Ⅲ）配合物的对应异构体[Co（L-thr）3]·4.5H₂O（L-1）和[Co（L-thr）₃]·4.5H₂O（D-1）,并对2个化合物进行了单晶X射线衍射、红外、热重、紫外可见光谱以及CD谱性质研究。晶体结构分析表明,2个化合物分别结晶在四方晶系P4₃2₁2和P4₁2₁2手性空间群。固体CD谱测试进一步证实2个化合物具有手性。     

两对由乳酸衍生物和刚性辅助配体构建的螺旋单一手性配位聚合物：合成、结构和性质

利用水热合成条件,在辅助配体帮助下,乳酸衍生物与Zn²⁺反应合成出了2对单一手性的配位聚合物,即{[Zn（（R）-CBA）（1,3-DIMB）]·H₂O}_n（1-D）、{[Zn（（S）-CBA）（1,3-DIMB）]·H₂O}_n（1-L）、[Zn₂（（R）-CBA）₂（1,4-BMIP）]_n（2-D）和[Zn₂（（S）-CBA）₂（1,4-BMIP）₂]_n（2-L）。结构分析揭示上述所有配合物都包含由CBA^2-配体与Zn（Ⅱ）离子构建而成的螺旋链。此外,刚性的辅助配体1,3-DIMB和1,4-BMIP在结构多样性中发挥了重要作用。测试了配合物的热稳定性、固态圆二色谱、荧光性质等。研究结果表明半刚性乳酸配体可以有效地合成螺旋结构的单一手性配位聚合物。     

芳基四硫富瓦烯与溴化铜电荷转移复合物的合成及晶体结构

采用溶液扩散的方法合成了硫原子桥联芳基取代四硫富瓦烯1~4与CuBr₂的4种电荷转移复合物（1^+·）（Cu₂Br₆）_0.5、（2^+·）（Cu₂Br₆）_0.5、（3^+·）（Cu₂Br₆）_0.5和（4^+·）（CuBr₂）。晶体结构研究表明,复合物中阴离子呈现2种构型：八面体型（Cu^Ⅱ₂Br₆）^2-和直线型（Cu^ⅠBr₂）^-,并且4种复合物呈现不同的堆积结构。通过调控芳基上卤素原子取代位置和大小,实现了对电荷转移复合物堆积结构和阴离子构型的有效调控。     

手性铁、镍席夫碱配合物的合成、结构及其与DNA相互作用研究

以手性苯乙胺与吡啶醛缩合得到的含双齿或三齿配位基的手性席夫碱（L1、L2）为配体,合成了4对单核铁、镍手性对映体配合物fac-Λ-[M（R-L1）₃]（ClO₄）₂·3CH₃CN（M=Fe,1R-Fe;M=Ni,1R-Ni）,fac-Δ-[M（S-L₁）₃]（ClO₄）₂·3CH₃CN（M=Fe,1S-Fe;M=Ni,1S-Ni）,[M（R-L₂）₂]（ClO₄）₂（M=Fe,2R-Fe;M=Ni,2R-Ni）,[M（S-L₂）₂]（ClO₄）₂（M=Fe,2S-Fe;M=Ni,2S-Ni）。利用红外光谱（IR）、核磁共振氢谱（1HNMR）、元素分析（EA）、X-射线单晶衍射等手段对配合物结构进行了表征。对化合物1R-Fe,1R-Ni,1S-Ni,2R-Fe进行了晶体结构分析,其中1R-Fe,1R-Ni,1S-Ni结晶于P2₁3手性空间群,金属中心与3个二齿配体（L1）提供的6个氮原子配位形成了扭曲变形的八面体结构;R型配体诱导配合物形成fac-Λ构型,而S型配体诱导配合物形成fac-Δ构型。2R-Fe结晶于P2₁2₁2₁手性空间群,二价铁离子与2个三齿配体（R-L2）提供的6个氮原子配位形成了扭曲变形的八面体结构。利用紫外-可见吸收光谱、荧光猝灭光谱、圆二色谱等光谱分析法研究了配合物与DNA的相互作用。研究结果表明这4对手性配合物均能与小牛胸腺CT-DNA发生不同强度的结合,结合稳定常数从4.41×10³L·mol^-1到1.88×10⁴L·mol^-1。配合物与DNA的结合模式可能是通过静电作用与DNA骨架发生沟面结合。金属中心为铁的配合物表现出比相应的镍配合物更强的DNA作用力;而含三齿配体L2的配合物与DNA的作用均比相应的含二齿配体L1的配合物更强;S型配体形成的配合物与DNA的结合能力优于R型配体形成的配合物。     

芳基取代四甲基环戊二烯基铼羰基化合物的合成、晶体结构及催化性能

芳基取代的四甲基环戊二烯 C₅HMe₄Ar（Ar=Ph,4-CH₃Ph,4-OCH₃Ph,4-ClPh,4-BrPh） 分别与Re₂（CO）₁₀在二甲苯中加热回流,得到了5个单核配合物[（η⁵-C₅Me₄Ar）Re（CO）₃]（Ar=Ph （1）,4-CH₃Ph （2）,4-OCH₃Ph （3）,4-ClPh （4）,4-BrPh （5））。通过元素分析、红外光谱、核磁共振氢谱对配合物1~5的结构进行了表征,用X射线单晶衍射法测定了配合物的结构。同时,研究了这五种配合物在芳香族化合物Friedel-Crafts烷基化反应中的催化活性。     

芳基取代四甲基环戊二烯基铼羰基化合物的合成、晶体结构及催化性能

芳基取代的四甲基环戊二烯 C₅HMe₄Ar（Ar=Ph,4-CH₃Ph,4-OCH₃Ph,4-ClPh,4-BrPh） 分别与Re₂（CO）₁₀在二甲苯中加热回流,得到了5个单核配合物[（η⁵-C₅Me₄Ar）Re（CO）₃]（Ar=Ph （1）,4-CH₃Ph （2）,4-OCH₃Ph （3）,4-ClPh （4）,4-BrPh （5）]。通过元素分析、红外光谱、核磁共振氢谱对配合物1~5的结构进行了表征,用X射线单晶衍射法测定了配合物的结构。同时,研究了这五种配合物在芳香族化合物Friedel-Crafts烷基化反应中的催化活性。     

手性有机酸薄层色谱保留指数的拓扑模型

基于Kier的分子连接性指数及邻接矩阵提出新型分子连接性指数（^mG_t^v）;引入手性指数（w_j）并建立了手性连接性指数（^mG_t^v）：^mG_t^v=^mG_t^v×w_j。^mG_t^v适用于手性分子、非手性分子及内消旋异构体的结构差异表征。用多元统计回归研究18种手性羟酸和氨基酸的薄层色谱保留指数（R_M）与^mG_t^v的定量构效关系,经最佳变量子集回归建立其四元数学模型,传统的判定系数（R²）为0.973,逐一剔除法（leave-one-out,LOO）的交互验证系数（Q²）为0.950,结果证明具有良好的稳健性及预测能力。根据进入该模型的4个手性连接性指数（⁰C_p^v、²C_p^v、C_ch^v、⁵C_p^v）可知,影响手性有机酸保留指数的主要因素是分子的二维结构特征和分子的手性特征以及柔韧性、折叠程度等三维结构因素。从上可见,新建手性连接性指数对手性有机酸的保留指数表征具有合理性与有效性,为预测手性有机酸的保留指数提供了一种有效方法。     

Cooperative Catalysis by Palladium and a Chiral Phosphoric Acid: Enantioselective Amination of Racemic Allylic Alcohols

Cooperative catalysis by [Pd(dba)₂] and the chiral phosphoric acid BA1 in combination with the phosphoramidite ligand L8 enabled the efficient enantioselective amination of racemic allylic alcohols with a variety of functionalized amines. This catalytic protocol is highly regio‐ and stereoselective (up to e.r. 96:4) and furnishes valuable chiral amines in almost quantitative yield.     

Enantiomeric Recognition of d- and l-Amino Acid Methyl Ester Hydrochlorides by New Chiral Bis-pyridino-18-crown-6 Substituted with Urea, and Diphenyl Groups

The article reports the synthesis and chiral recognition properties of a new chiral bis-pyridino-18-crown-6 (7), having urea, diphenyl, and allyloxy groups. The chiral bis-pyridino-18-crown-6 was prepared by a thirteen-steps procedure from the commercially available (S)-(+)-mandelic acid and chelidamic acid. The association constants (K _a) (1.33 × 10³–3.20 × 10³) for enantiomeric recognition of d- and l-amino acid methyl ester hydrochlorides using the chiral bis-pyridino-18-crown-6 have been examined by ¹H-NMR titration method in CDCl₃ at 25 °C. The chiral bis-pyridino-18-crown-6 showed higher association constants for the d-series amino acid methyl ester (d-AlaOMe, d-LeuOMe, d-MetOMe) hydrochlorides as compared to the corresponding l-series (l-AlaOMe, l-LeuOMe, l-MetOMe) hydrochlorides.     

Cr-MIL-101-NH2的手性后合成修饰

采用后合成修饰技术（postsynthetic modification,PSM）设计并合成手性金属-有机框架化合物（metal-organic frameworks,MOFs）,将L型脯氨酸衍生物Boc-L-ProCl,后修饰到金属有机-框架化合物Cr-MIL-101-NH₂孔道中,制得手性金属有机-框架化合物Cr-MIL-101-PaB₂。经核磁（¹H NMR）结果证实,修饰产率高达64%,固体圆二色谱（CD）测试结果表明经后合成修饰后的Cr-MIL-101-PaB₂具有旋光性。红外光谱（IR）、氮气脱附-吸附、热重（TGA）、粉末X射线衍射（PXRD）手段对其进行表征。实验结果证实,为避免金属-有机框架化合物自组装的不确定性,采用后合成修饰技术,可按需合成手性金属有机-框架化合物。     

Cr-MIL-101-NH_2的手性后合成修饰

采用后合成修饰技术(postsynthetic modification,PSM)设计并合成手性金属-有机框架化合物(metal-organic frameworks,MOFs),将L型脯氨酸衍生物Boc-L-ProCl,后修饰到金属有机-框架化合物Cr-MIL-101-NH_2孔道中,制得手性金属有机-框架化合物Cr-MIL-101-PaB_2。经核磁(~1H NMR)结果证实,修饰产率高达64%,固体圆二色谱(CD)测试结果表明经后合成修饰后的CrMIL-101-PaB_2具有旋光性。红外光谱(IR)、氮气脱附-吸附、热重(TGA)、粉末X射线衍射(PXRD)手段对其进行表征。实验结果证实,为避免金属-有机框架化合物自组装的不确定性,采用后合成修饰技术,可按需合成手性金属有机-框架化合物。     

Synthesis of Novel Chiral C 2-symmetric Diaza-18-crown-6 Ether Derivatives and their Enantioselective Recognition of Amino Acid Derivatives

New chiral diaza-18-crown-6 ether derivatives, 5 and 6 were synthesized from (R)-(-)-2-amino-1-bütanol. These chiral artificial receptors exhibit pronounced chiral recognition toward the enantiomers of l- and d- amino acid derivatives. The highest enantioselectivity was observed in the case of Trp-OMe·HCl (K_D/K_L=12.5).     

A novel pillar[3]trianglimine macrocycle with a deep cavity used as a chiral selector to prepare a chiral stationary phase by thiol-ene click reaction for enantioseparation in high-performance liquid chromatography

A chiral pillar[3]trianglimine (C₆₀H₇₂N₆O₆) with a deep cavity has been developed as a chiral selector and bonded to thiolated silica by thiol-ene click reaction to fabricate a novel chiral stationary phase for enantioseparation in high-performance liquid chromatography. The enantioseparation performance of the fabricated chiral stationary phase has been evaluated by separating various racemic compounds, including alcohols, esters, amines, ketones, amino acids, and epoxides, in both normal-phase and reversed-phase elution modes. In total, 14 and 17 racemates have been effectively separated in these two separation modes, respectively. In comparison with two widely used chiral columns (Chiralcel OD-H and Chiralpak AD-H), our novel chiral stationary phase offered good chiral separation complementarity, separating some of the tested racemates that could not be separated or were only partially separated on these two commercial columns. The influences of analyte mass, mobile phase composition, and column temperature on chiral separation have been investigated. Good repeatability, stability, and column-to-column reproducibility of the chiral stationary phase for enantioseparation have been observed. After the fabricated column had been eluted up to 400 times, the relative standard deviations (n = 5) of resolution (Rs) and retention time of the separated analytes were < 0.39% and < 0.20%, respectively. The relative standard deviations (n = 3) of Rs and retention time for column-to-column reproducibility were < 4.6% and < 5.2%, respectively. This study demonstrated that the new chiral stationary phase has great prospects for chiral separation in high-performance liquid chromatography.     

Highly diastereoselective synthesis of arylglycine derivatives via TFA-promoted Friedel-Crafts reactions of phenols with cyclic glyoxylate imines

Optically active α-arylglycine derivatives were synthesized by Brønsted acid (TFA)-promoted Friedel-Crafts reaction of various phenols with chiral cyclic glyoxylate imines (2a-c), followed by deprotection with Pd(OH)₂/C under H₂. The diastereoselectivities of the initially formed F-C reaction products are up to 99%.     

Scorpio-Ligand: Synthesis of Biphenyl-Dihydroazepine Phosphoramidite Ligands for Asymmetric Hydrogenation

A novel dihydroazepine-bridged BIPHEP phosphoramidite ligand with an amino acid moiety in the backbone was synthesized and evaluated in the Rh-catalyzed asymmetric hydrogenation. The scorpion tail-like amino acid backbone is capable of hydrogen bond formation and able to shift the rotamer composition of the biphenyl axis with the two scissor-like arms. Pivaloyl-l -valine was studied as chiral selector unit and compared with pivaloylglycine as the achiral reference substance. The enantiomerization barrier of the pivaloylglycine-modified biphenylamide was determined to be ΔG^≠=110 kJ/mol. In the case of pivaloyl-l -valine, the (S_ax) isomer is thermodynamically favored. Due to the relatively high barrier, the ligand is atropisomeric at room temperature and allows the preparative separation of the stereoisomers. The obtained phosphoramidite ligands were separated by chiral HPLC. For the first eluting rotamer, Rh complex ([Rh(cod)(L)₂]BF₄) was generated in situ and examined in the enantioselective hydrogenation of 2-acetamidoacrylate and methyl 2-acetamido-3-phenylacrylate, achieving enantiomeric excesses of up to 94 %.     

Easy Access to Enantiomerically Pure Heterocyclic Silicon-Chiral Phosphonium Cations and the Matched/Mismatched Case of Dihydrogen Release

Phosphonium ions are widely used in preparative organic synthesis and catalysis. The provision of new types of cations that contain both functional and chiral information is a major synthetic challenge and can open up new horizons in asymmetric cation-directed and Lewis acid catalysis. We discovered an efficient methodology towards new Si-chiral four-membered CPSSi* heterocyclic cations. Three synthetic approaches are presented. The stereochemical sequence of anchimerically assisted cation formation with B(C₆F₅)₃ and subsequent hydride addition was fully elucidated and proceeds with excellent preservation of the chiral information at the stereogenic silicon atom. Also the mechanism of dihydrogen release from a protonated hydrosilane was studied in detail by the help of Si-centered chirality as stereochemical probe. Chemoselectivity switch (dihydrogen release vs. protodesilylation) can easily be achieved through slight modifications of the solvent. A matched/mismatched case was identified and the intermolecularity of this reaction supported by spectroscopic, kinetic, deuterium-labeling experiments, and quantum chemical calculations.