配位化学中的镜面对称性破缺——纪念配位化学创始人维尔纳首次拆分八面体Co(Ⅲ)络合物100周年

镜面对称性破缺(MIrrOr SyMMETry brEAkIng,简称MSb),是指在一个热力学非平衡体系中非零EE值的状态可以自发地从非手性或消旋态中产生的现象。随着现代X射线衍射技术对晶体结构的阐明以及固体Cd光谱表征方法的日益普及,在配位化学领域中发现的各种MSb现象层出不穷,但是其预测和调控及其发生的某些真实机理仍旧是悬而未决的科学难题。本文介绍与MSb现象(自发拆分和绝对不对称合成)相关的概念、表征方法和实例,并特别探讨了单核或寡聚惟手性金属中心络合物MSb现象的研究及其应用。国家自然科学基金项目(20973136;20773098);国家基础科学人才培养基金项目(J1030415

配位化学中的镜面对称性破缺(续)——纪念配位化学创始人维尔纳首次拆分八面体Co(Ⅲ)络合物100周年

通讯联系人,E-mail: huizhang@ xmu.edu.cn国家自然科学基金项目(No.20973136,No.20773098);国家基础科学人才培养基金项目(No.J1030415

Photoinduced intramolecular charge transfer of sodium 4-(N,N-dimethylamino)benzenesulfonate

A new dual fluorescent N,N-dimethylaniline derivative, sodium 4-(N,N-dimethylamino)benzenesulfonate (SDMAS), is reported. In SDMAS, the electron acceptor is linked to the phenyl ring via a sulfur atom at the para-position of the electron donor. It was found that SDMAS emits dual fluorescence only in highly polar solvent water but not in organic solvents such as formamide, methanol and acetonitrile. In organic solvents only a single-band emission at ca.360 nm was observed in the short wavelength region. The dual fluorescence of SDMAS in water was found at 365 and 475 nm, respectively. Introduction of organic solvent such as ethanol, acetonitrile, and 1,4-dioxane into aqueous solution of SDMAS leads to blue-shift and quenching of the long-wavelength emission. Measurements of steady-state and picosecond time-resolved fluorescence indicate that the long wavelength fluorescence is emitted from a charge transfer (CT) state that is populated from the locally excited (LE) state, with the latter giving off the short wavelength fluorescence. The fact that a highly polar solvent is required to bring out the dual fluorescence suggests that the CT process of SDMAS has a high activation energy (E-a). In supporting this assumption the time-resolved fluorescence measurements give an E-a of 15.35 kJ . mol(-1). It was assumed that the participation of the sulfur atom d-orbital in the conjugation of sulfonate group with phenyl ring and the strong twisting and inverting of the dimethylamino plane relative to the phenyl ring could be the reasons for the high activation energy. A molecular configuration change upon charge transfer in water was suggested for SDMAS based on the thermodynamic data. SDMAS reported here represents the example of the dual fluorescent amine substituted aromatic sulfonate

Copper(Ⅱ) Ion Coordination-Controlled Twisted Intramolecular Charge Transfer Dual Fluorescence Emission

设计合成了2个分子内扭转电荷转移(TICT)荧光体(1和2),铜离子的配位作用可开关其双重荧光发射。2在乙腈/水溶液(1∶1,V/V)中的双重荧光发射随着铜离子的加入以类似电子转移机制“开-关“形式猝灭,而1在铜离子与其计量比为1之内的乙腈/水溶液(1∶1,V/V)中,其双重荧光发射随着铜离子的加入逐渐猝灭;在计量比之后其长波长的TICT荧光发射随着铜离子的加入逐渐增强。即1的TICT荧光发射以“开-关-开“的机制被铜离子诱导。同时还获得了铜离子与1形成的配合物的晶体结构以及配合物的荧光性质。1H nMr波谱滴定实验表明荧光体的电荷转移程度是影响TICT发射的主要因素,1是一个新的且其TICT发射可以被铜离子调制为“开-关-开“的TICT荧光体。Two twisted intramolecular charge transfer(TICT) fluorophores(1 and 2) were designed and synthesized to control the dual fluorescence emission by Cu2 +coordination.The dual fluorescence of 2 is quenched upon the addition of Cu2+ions in an "on-off" process similar to PET inhibition.The dual fluorescence of 1 exhibits emission quenching initially and then long-wavelength band(TICT band) emission enhancement with "on-off-on" signalling behaviour.The crystal structure of the Cu2+complex with 1 was also obtained, and its fluorescence properties were reported.1H NMR spectral titration results indicate that the degree of charge transfer is a crucial factor for the resulting TICT state emission.Fluorophore 1 is a new TICT compound in which TICT emission can be tuned by copper ions with a dramatic change via "on-off-on" signalling behaviour.CCDC: 899958, Cu2+-1.国家自然科学基金(No.21271150); 国家基础科学人才培养基金(No.J1310024)资助项

计算化学数据与图形在普通化学教学中的运用

鉴于近化学类的非化学专业院系较少开设物理化学和结构化学课程,他们接触到的计算化学知识十分有限,通过对普通化学教学过程中适当引用一些计算化学的模拟研究内容,有利于开拓学生的视野,调动学生学习积极性,更新普通化学教学内容,培养大学生的思维能力,从而提高教学质量。厦门大学校级教改项目(201718

综合化学实验——DMB的绝对不对称合成和表征

介绍一个可用于化学系本科生开设的综合化学实验。该实验构思源于手性对二甲氨基苯甲醛缩氨基苯硫脲(DMB)的绝对不对称合成。学生可通过实验发现、观察和探究手性对称性破缺的奇妙现象,并掌握标题化合物组成、结构和手性性质的各种表征方法,特别是固体圆二色(CD)光谱方法

Synthesis, crystal structure and fluorescent properties of 1-(4-(dimethylamino)benzylidene)4-(naphthalen-1-yl) thiosemicarbazide

The title compound, 1-4-(dimethylamino)benzylidene)-4-(naphthalene-1-yl) thiosemicarbazide (DMABNTS, C20H20N4S, M-r = 348.47), was synthesized and characterized by elemental analysis, IR, H-1 NMR and MS. The crystal structure of DMABNTS with 1,4-dioxane (Diox, C4H8O2) solvent molecules (DMABNTS(.)2Diox, C28H36N4O4S, M-r = 524.67) was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic system, space group P2(1)/c with a = 14.418(4), b = 7.1702(19), c = 28.350(7) angstrom, beta = 101.154(6)degrees, V = 2875.4(13) angstrom(3), Z = 4, D-c = 1.212 g/cm, F(000) = 1120 and mu = 0.151 mm(-1). A total of 6458 reflections were collected, of which 4671 were unique. The structure was solved by direct methods and refined to the final R = 0.0732 and wR = 0.2127 for 3921 observed reflections (I > 2 sigma(I)). There exist intermolecular hydrogen bonds (N(2)-H(2B)center dot center dot center dot S(1A) and N(1)-H(1A)center dot center dot center dot O(4B)) in the structure. The study of fluorescent properties shows that DMABNTS emits bright solid-state fluorescence in the visible region and exhibits blue photoluminescence

TICT荧光探针法研究甲基化的β-环糊精空腔微环境

p-dimethylaminobenzonitrile (DMABN), a typical dual fluorescent flurophor (TICTflurophore), was used as fluorescent probe. The microenviromental property of twelve methyl modified β-cyclodextrin(methyl β-CD) was compared with that of β-cyclodextrin (β-CD). Results showed that the polarity of the cavity of methyl β-CD is lower than that of β- CD, and the capacity of methyl β-CD inclusion with DMABN is stronger than that of β-CD inclusion with DMABN

TICT荧光探针法研究甲基化的β-环糊精空腔微环境

p-dimethylaminobenzonitrile (DMABN), a typical dual fluorescent flurophor (TICTflurophore), was used as fluorescent probe. The microenviromental property of twelve methyl modified β-cyclodextrin(methyl β-CD) was compared with that of β-cyclodextrin (β-CD). Results showed that the polarity of the cavity of methyl β-CD is lower than that of β- CD, and the capacity of methyl β-CD inclusion with DMABN is stronger than that of β-CD inclusion with DMABN

磺基水杨酸的分子内质子转移及其在酸性锡电镀液中的荧光快速测定

根据磺基水杨酸反常大的荧光Ｓｔｏｋｅｓ位移的实验现象，提出了它在一定条件下发生分子内质子转移的机理．据此建立了酸性锡电镀液中磺基水杨酸的直接快速荧光分析新方法．该方法不受共存组分干扰，５～１０ｍｉｎ可完成测定，测定的相对标准偏差小于３％