A Homochiral Fulgide Organic Ferroelectric Crystal with Photoinduced Molecular Orbital Breaking

Thermally triggered spatial symmetry breaking in traditional ferroelectrics has been extensively studied for manipulation of the ferroelectricity. However, photoinduced molecular orbital breaking, which is promising for optical control of ferroelectric polarization, has been rarely explored. Herein, for the first time, we synthesized a homochiral fulgide organic ferroelectric crystal (E)-(R)-3-methyl-3-cyclohexylidene-4-(diphenylmethylene)dihydro-2,5-furandione ( 1 ), which exhibits both ferroelectricity and photoisomerization. Significantly, 1 shows a photoinduced reversible change in its molecular orbitals from the 3 π molecular orbitals in the open-ring isomer to 2 π and 1 σ molecular orbitals in the closed-ring isomer, which enables reversible ferroelectric domain switching by optical manipulation. To our knowledge, this is the first report revealing the manipulation of ferroelectric polarization in homochiral ferroelectric crystal by photoinduced breaking of molecular orbitals. This finding sheds light on the exploration of molecular orbital breaking in ferroelectrics for optical manipulation of ferroelectricity.     

偶氮苯类DNA纳米机器

具备光致异构性及乏氧响应性的偶氮苯为构建DNA纳米机器提供了动态响应元件. 然而, 受限于偶氮苯类化合物有限的光异构化反应, 偶氮苯类DNA纳米机器的构建与应用仍然面临着巨大的挑战. 本文梳理了基于偶氮苯的DNA纳米机器的构建方式及相应优缺点, 总结了可见光响应的偶氮苯类DNA纳米机器的设计规则, 并进一步综合评述了偶氮苯类DNA纳米机器在调控酶活性、 物质运输和机械运动等方面的应用. 本文有望推动开发更灵活的偶氮苯与DNA的偶联方式, 并为偶氮苯类DNA纳米机器在生物医学上的应用带来一定启示.     

Different shapes of spherical vaterite by photo-induced cis–trans isomerization of an azobenzene-containing polymer in a mixture of dimethyl sulfoxide and water

We studied the crystallization of CaCO₃ by the photoisomerization of azobenzene groups in poly[1-[4-[3-carboxy-4-hydroxyphenylazobenzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) in a mixture of dimethyl sulfoxide and water at 30 °C. The products were characterized by scanning electron microscopy (SEM), FT-IR, and powder X-ray diffraction (XRD) analysis. We observed that the different shapes of spherical vaterite particles were produced by the changes of configuration and polarity of the azobenzene groups in the polymer which resulted from photo-induced isomerization. The results indicate that the nucleation of primary particles of CaCO₃ was inhibited by in situ photo-induced cis–trans isomerization of PAZO. Therefore, we suggest that the shapes of the spherical vaterite can be effectively modified by photoisomerization of the azobenzene groups in the polymer at the initial stage of CaCO₃ crystallization.     

The photoisomerization of <Emphasis Type="Italic">trans</Emphasis>-stilbene in Triton X-100/<Emphasis Type="Italic">n</Emphasis>-C<Subscript>5</Subscript>H<Subscript>11</Subscript>OH/H<Subscript>2</Subscript>O microemulsions

Different from organic solvent, self-assemblies are environment friendly media, and moreover, if they are used as micro-reactor, many meaningful and exciting results may be obtained. In this paper, we investigated the photoisomerization of trans-stilbene in Triton X-100/n-C₅H₁₁OH/H₂O microemulsions (a kind of self-assemblies) with different compositions and structures to establish the relationship between the reaction yields and the compositions and structures of microemulsions. The results show that the yield of cis-stilbene is increased with the increase of water content or with the decrease of Triton X-100 content, and oil in water (O/W) structure is the best structure for this reaction, which makes it possible to decrease the pollution of environment by organic solvent always used in organic reactions.     

侧链偶氮聚电解质在胶体微球表面的静电层层自组装和微胶囊制作

将侧链偶氮聚电解质应用于聚苯乙烯胶体微球表面的静电层层自组装,得到了偶氮聚电解质和聚二烯丙基二甲基氯化铵多层膜覆盖的核壳微球.实验表明,组装后偶氮苯基团发生了一定程度的解聚集,得到的胶体微球可表现出明显的光色效应.研究进一步采用含肉桂酸酯的光敏聚电解质作为交联的保护壳层,并通过光交联反应使表面层发生交联固化反应.将上述具有核壳结构的胶体球溶解去除聚苯乙烯内核后,得到了含光响应聚电解质的空心微胶囊.     

Effect of surfactant structure on catalysis of microemulsion for photoisomerization of trans-stilbene

In this study,the photoisomerization of trans-sfilbene was carried out in water in oil (W/O) microemulsions by using sodium dodecyl sulfate (SDS),dodecyl trimethyl ammonium bromide (DTAB) and cetyl trimethyl ammonium bromide (CTAB) as surfactant,respectively.The catalytic effect of microemulsion on this reaction is closely related to the structure of surfactant.When there is no photosensitizer 9,10-dicyanoanthracene (DCA),the surfactant with shorter hydrophobic chain is preferred,while in the presence of DCA,the surfactant with anionic polar group is preferred.     

A different photo-sensitivity of isostructural crystals of N-(3,5-dihalosalicylidene)-2,6-dimethylaniline analogues: search for the definite reaction room in the crystal to exhibit photochromism

Photo-sensitivity and X-ray crystal structure of three N-(3,5-dihalosalicylidene)-2,6-dimethylaniline analogues were determined to reveal a definite space maintained in the photochromic crystals.     

端基含己氧基偶氮苯基元的一代光致变色液晶碳硅烷树状物的光响应行为研究

研究了端基含己氧基偶氮苯基元新的一代碳硅烷光致变色液晶树状物G1及其偶氮基元化合物M3在各种溶液中的反顺光异构化反应速率常数、光回复异构化反应速率常数、热回复异构化反应速率常数、量子产率、活化能和异构转换率.G1和M3的光致变色速率常数为0.1s^-1,比对应的光致变色液晶聚硅氧烷的光响应速度快10⁷倍.     

Thiazolylazopyrazoles as Nonsymmetric Bis-Heteroaryl Azo Switches: High-Yield Visible-Light Photoisomerization and Increased Z-Isomer Stability by o-Carbonylation

Following the progress on mono-heteroaryl azo switches (Het-N=N-Ph), a few bis-heteroaryl azo switches (Het-N=N-Het) have been studied recently, whereas the nonsymmetric bis-heteroaryl ones (Het₁-N=N-Het₂) that can combine the respective merits of each heterocycle, have received little attention. Here we report thiazolylazopyrazoles as nonsymmetric bis-heteroaryl azo switches that combine the visible-light switching character of the thiazole ring and the ease of o-substitution of the pyrazole ring. Thiazolylazopyrazoles can achieve (near-)quantitative visible-light isomerization in both directions and long Z-isomer thermal half-lives of several days. In contrast to the drastically destabilizing effect of o-methylation, o-carbonylation of the pyrazole ring can remarkably stabilize Z isomers by inducing attractive intramolecular interactions (dispersion, C−H⋅⋅⋅N bond, and lone-pair⋅⋅⋅π interaction). Our work highlights the importance of the rational combination of two heterocycles and suitable structural substitution in developing bis-heteroaryl azo switches.