Photochromic Properties of New Dithienylethene Copolymer

Photochromic molecular switches can be important memory media for optical information processing and storage as long as their thermal stability and photo-fatigue resistance met certain criteria. Among many photochromic materials, heterocyclic diarylethenes have displayed desirable optical switching characteristics. Specifically, bisthienylethene (BTE)-based photochromic switches have demonstrated high sensitivity and rapid response as well as thermal- and photostability^[1,2]. It has been shown that various BTEs can undergo ca.l0^[4] cycles before significant evidence of fatigue^[3]. It is important that molecules with otherwise improved switching characteristics retain this level of fatigue resistance. For example, the improved characteristics include that the absorption of close form of photochromic materials should be shifted to shorter wavelength region due that semiconductor laser shift to short wavelength are developing trend for high density information storage. Also, fatigue may be different in the solid state than in solution. In general, precedent photochromic polymers consisted of photochromic molecules either dispersed in a matrix or covalent grafted onto the polymer main chain.     

A multiple switching bisthienylethene and its photochromic fluorescent organogelator

A multiple switching fluorescent photochromic bisthienylethene bridged naphthalimide bearing cholesteryl groups was synthesized and its organogelator showed excellent photo-responsive and thermal reversible performance by light, thermal.     

Synthesis and photochromism of a new binuclear porphyrazinato magnesium(II)

The synthesis, characterization and photochromism of a new coplanar binuclear porphyrazine bearing six bis-(trimethylthiophenyl) photochromic functionalities at the periphery are described. The synthetic route is concise and the near-infrared luminescence changes of this binuclear porphyrazine can be regulated in a reversible manner by the photoisomerization of the bisthienylethene moiety.     

Novel Bisthienylethene Containing Ferrocenyl‐Substituted Naphthalimide: A Photo‐ and Redox Multi‐Addressable Molecular Switch

A new photochromic bisthienylethene system (BTE? NAFc) is reported in which the ferrocene unit (Fc) is incorporated into a naphthalimide chromophore as the central ethene bridging unit. The incorporated Fc unit in the photochromic system of BTE? NAFc has several effects on optical properties, such as fluorescence‐modulation through photoinduced electron transfer (PET), a decrease in the photochromic cyclization quantum yield, and a selective two‐step oxidation process. The ability to drive ring‐opening and ring‐closing reactions with a secondary redox‐modulation provides increased functionality to the photochromic system. Based on these meaningful photo‐ and redox‐modulation properties, five unprecedented multi‐addressable states (BTE? NAFc, BTE? NAFc⁺, c‐BTE? NAFc, c‐BTE? NAFc⁺, and BTE⁺? NAFc⁺) and gated photochromism are successfully obtained within the unimolecular BTE platform, thus providing deeper insight into photochromic systems as multifunctional outputs.     

Multicolor Chromism from a Single Chromophore through Synergistic Coupling of Mechanochromic and Photochromic Subunits

We report a versatile mechanophore exhibiting a vividly detectable, light-regulable multicolor mechanochromism. Such optical features rely on the synergistic coupling of mechanochromic bis-rhodamine (Rh) and photochromic bisthienylethene (BTE). Poly(methyl acrylate)s incorporating this bis-mechanophore can be mechanically activated under sonication. The relative distribution of the two distinctly colored and fluorescent Rh ring-opening products is altered with different magnitudes of applied force. Orthogonal use of the photochromic reaction of the BTE core can strengthen the mechanochromism and gate the mechanofluorescence in polymers. Due to increased conjugation offered by the BTE linker, both force- and light-induced optical signals display high contrast. Combined DFT simulated and experimental results reveal that the three subunits (two Rhs and one BTE) in this chromophore are activated sequentially, thus generating switchable three-colored forms and gradient optical responses.     

四硫富瓦烯衍生物在有机光电功能材料方面的研究进展

四硫富瓦烯(TTF)及其衍生物不仅是分子导体的有效构筑模块之一, 而且在材料化学的诸多领域显示了广阔的应用前景. 本工作综述了近几年TTF及其衍生物在非线性光学、分子光电器件、光伏器件及光致变色方面的最新研究进展.     

多功能二噻吩乙烯光致变色光分子开关材料

光致变色材料是一类在不同波长的光交替照射下,产生两种可进行可逆转换的光致异构体并伴随明显的光物理和光化学性能变化的材料。基于其特殊的光致异构性质,人们已开发出多种光致变色功能材料并将其广泛应用于超高密度光信息存储、分子开关、分子逻辑门、分子导线、光电材料、多光子器件、表面/纳米器件、液晶材料、化学传感、生物成像、自组装、聚集诱导发光、光控生物体系等诸多领域。其中,二噻吩乙烯类化合物因其出色的热稳定性、优良的耐疲劳性、快的响应速率、高的转化率和量子产率以及出色的固相反应活性而成为理想的光致变色材料之一。本文主要围绕近期本研究组研究成果着重介绍近几年二噻吩乙烯类化合物从溶液体系到功能化表面体系的研究进展,探讨当前该领域存在的问题并对其前景和发展方向进行展望。     

光控二芳烯化学传感器及其研究进展

有机光致变色材料由于在光学记忆及分子开关器件等领域具有潜在的应用价值而备受关注。在众多有机光致变色系统中,二芳烯类光致变色化合物具有热稳定性好、耐疲劳、响应速度快和灵敏度高等优点,在光电材料和生物医学领域具有广阔的应用前景。近年来,围绕二芳烯构建可调控光化学传感器已成为功能材料领域的一大研究热点。本文主要介绍以二芳烯作为光调控单元合成具有多重调控功能的化学传感器的研究进展,并展望了该领域的应用前景和研究方向。     

Recent progress of luminescent metal complexes with photochromic units

Photo-responsive molecules have been studied extensively because of their light irradiation abilities that enable modulation of certain physical and chemical properties in emerging molecular electronic and photonic devices. For advanced photonic applications, photochromic metal complexes that have photochromic units as the photo-responsive ligand are highly desirable, as they allow improvement of the photochromic properties and their photo-switching functionality. This article focuses on recent progress in luminescent metal complexes with photochromic units. Luminescence-switching properties of photochromic metal complexes depend on characteristic electronic transitions. The electronic transitions of photochromic metal complexes can be divided into three categories: (1) π–π* transition of the ligand, (2) metal to ligand charge transfer (MLCT) in transition-metal complex, and (3) f–f transition in lanthanide complex. Luminescence modulation using various metal complexes with photochromic units has been studied extensively in recent years, and various applications for future molecular switching devices are expected in the field of advanced photonics. Based on the literature and our studies on luminescent metal complexes with photochromic units, we report on the recent progress of luminescent metal complexes with photochromic units.     

双功能螺吡喃螺噁嗪类光致变色化合物研究进展

光致变色材料在光学镜头、光学信息存储、光分子开关等方面具有广泛的应用.双功能光致变色材料的合成与应用研究越来越受关注.综述了以螺吡喃、螺噁嗪为光致变色基团的双功能光致变色化合体系的研究进展,主要介绍了具有荧光性能、与金属离子络合性能的光致变色体系的研究进展以及应用.     

Recent progresses on diarylethene based photochromic switches

Organic photochromic materials have received considerable attention because of their potential for photonic applications, especially for fast and high density data storage. In 2000, Chemical Reviews published a special issue on photochromic materials including a review about the properties and applications of diarylethene photochromic compounds. Since then much impressive progress has been made in this area. Various new diarylethene derivatives have been prepared and examined. The tutorial review presented herein describes developments in diarylethene-based molecular switches made in the last three years. In addition, the synthetic aspects of diarylethene photochromic compounds, which are important issues and neglected in most previous reviews, have been included.     

Photomobile Polymer Materials with Crosslinked Liquid‐Crystalline Structures: Molecular Design,Fabrication, and Functions

Crosslinked liquid‐crystalline polymer materials that macroscopically deform when irradiated with light have been extensively studied in the past decade because of their potential in various applications, such as microactuators and microfluidic devices. The basic motions of these materials are contraction–expansion and bending–unbending, which are observed mainly in polysiloxanes and polyacrylates that contain photochromic moieties. Other sophisticated motions such as twisting, oscillation, rotation, and translational motion have also been achieved. In recent years, efforts have been made to improve the photoresponsive and mechanical properties of this novel class of materials through the modification of molecular structures, development of new fabrication methods, and construction of composite structures. Herein, we review structures, functions, and working mechanisms of photomobile materials and recent advances in this field.     

Liquid crystal polymers containing permanent dipole azobenzene chromophores

Three photochromic monomers containing a permanent dipole photochromic azobenzene group spaced from the methacryloyl moiety by a polymethylene segment were synthesized in three steps starting from 4-cyanoaniline. The monomers were homopolymerized and copolymerized with an optically active monomer, (-)-menthyl methacrylate, in the presence of AIBN as a radical initiator. Structurally similar amphiphilic polymers were obtained by homopolymerization of analogous methacrylates in which oligo(oxyethylene) segments replaced the polymethylene spacers. The polymeric materials, having a molar content of photochromic units between 5 and 100% and molecular weights of about 15,000, were characterized by thermal analysis, X-ray diffraction, 1D and 2D NMR. Mobility and photochromic properties in solution were also investigated.     

Recent developments in the field of metal complexes containing photochromic ligands: Modulation of linear and nonlinear optical properties

Organic photochromic molecules are important for the design of photoresponsive functional materials, as switches and memories. Over the past 10 years, research efforts have been directed towards the incorporation of photoresponsive molecules into metal systems, in order either to modulate the photochromic properties, or to photoregulate the redox, optical and magnetic properties of the organometallic moieties. This review article focuses on some of the recent work reported within the last few years in the area of organometallic and coordination complexes containing photochromic ligands for the photoregulation of optical and nonlinear optical properties. The first part is related to photochromic 1,2-diarylethene (DAE)-containing metal complexes, examples of mono- and multi-DAE metal-based will be discussed. The second part deals with metal complexes incorporating spiropyran and spirooxazine derivatives.     

Recent Process of Photo-responsive Materials with Aggregation-induced Emission

The research of photo-responsive materials, with changed absorption and emission under light stimulus, has drawn more and more attention due to their wide applications. However, most of them suffered from the notorious aggregation-caused quenching(ACQ) effect, which often led to the unconspicuous luminescent change in photo-responsive process. To solve this problem, the strategy of combining aggregation-induced emission(AIE) and photochromic properties was utilized, which largely enriched the phenomenon and application of photo-responsive materials. This short review summarized the recent progress of photo-responsive AIE materials with changed UV absorbance or PL phenomenon under UV-irradiation, including the types of molecular structures, internal mechanisms and the practical applications. Also, some outlooks were given on the further exploration of this field at the end of this paper.     

光致变色微胶囊的制备与性能

以蜜胺树脂为壁材、光致变色材料为芯材,采用原位聚合法制备了具有光致变色性能的微胶囊.研究了三聚氰胺/甲醛摩尔比、壁材与芯材的用量比、乳化剂浓度等因素对微胶囊形貌及性能的影响.在最佳工艺条件下制备的变色微胶囊,在日光和紫外光下具有快速、可逆的光致变色性能.     

Photochrome-coupled metal complexes: molecular processing of photon stimuli

The frontiers of novel photoresponsive materials constructed with photochromes and transition metal complexes are surveyed in this review. Strategies to develop new photofunctions are categorized into four types. In the first category, intramolecular electronic interactions between photochromes and metal complexes produce entangled responses such as redox-regulated photochromic reactions or tristable photochromism. In the second, light-induced molecular structural rearrangements of photochromes induce the transformation of flexible and labile coordination structures, which can be applied to complex photomechanics or photoelectron conversion. In the third, the photochromic moiety also acts as a photonic switch, transmitting a metal-metal interaction when it is located between two metal complex moieties. The last category concerns the development of new photochromic reactions, involving metal-ligand bond rearrangements. These reactions potentially induce drastic electronic tuning of the metal center, and can be used to develop light-driven molecular machines.     

Aromaticity-controlled thermal stability of photochromic systems based on a six-membered ring as ethene bridges: photochemical and kinetic studies

Three photochromic compounds-2-butyl-5,6-bis[5-(4-methoxyphenyl)-2-methylthiophen-3-yl]-1?H-benzo[de]isoquinoline-1,3(2?H)-dione (BTE-NA), 4,5-bis[5-(4-methoxyphenyl)-2-methylthiophen-3-yl]benzo[c][1,2,5]thiadiazole (BTA), and BTTA, which contain naphthalimide, benzothiadiazole, and benzobisthiadiazole as six-membered ethene bridges with different aromaticities-were systematically studied in solution, sol-gel, and single-crystal states. They exhibit typical photochromic performance with considerably high cyclization quantum yields. BTE-NA, BTA, and BTTA form a typical donor-π-acceptor (D-π-A) system with significant intramolecular charge transfer (ICT) between HOMO and LUMO upon excitation, thus realizing the fluorescence modulation by both photochromism and solvatochromism. The three ethene bridges with different degrees of aromaticity can provide a systematic comparison of the thermal stability evolution for their corresponding closed forms (c-BTE-NA, c-BTA, and c-BTTA). c-BTE-NA shows first-order decay in various solvents from cyclohexane to acetonitrile. c-BTA only shows first-order decay in polar solvents such as chloroform, whereas it is stable in nonpolar solvents like toluene. In contrast, the less aromatic property of BTTA gives rise to its unprecedented thermal stability in various solvents even at elevated temperatures in toluene (328?K). Moreover, the small energy barrier between the parallel and antiparallel conformers allows the full conversion from BTTA to c-BTTA. In well-ordered crystal states, all three compounds adopt a parallel conformation. Interestingly, BTTA forms a twin crystal of asymmetric nature with interactions between the electron-rich oxygen atom of the methoxy group and the carbon atom of the electron-deficient benzobisthiadiazole moiety. This work contributes to the understanding of aromaticity-controlled thermal stability of photochromic systems based on a six-membered ring as an ethene bridge, and a broadening of the novel building blocks for photochromic bisthienylethene systems.     

Photochromic organic-inorganic hybrid materials

Photochromic organic-inorganic hybrid materials have attracted considerable attention owing to their potential application in photoactive devices, such as optical memories, windows, photochromic decorations, optical switches, filters or non-linear optics materials. The growing interest in this field has largely expanded the use of photochromic materials for the purpose of improving existing materials and exploring new photochromic hybrid systems. This tutorial review summarizes the design and preparation of photochromic hybrid materials, and particularly those based on the incorporation of organic molecules in organic-inorganic matrices by the sol-gel method. This is the most commonly used method for the preparation of these materials as it allows vitreous hybrid materials to be obtained at low temperatures, and controls the interaction between the organic molecule and its embedding matrix, and hence allows tailoring of the performance of the resulting devices.     

Recent advances in photoresponsive supramolecular self-assemblies

Construction of supramolecular self-assemblies whose self-assembling process and self-assembled architectures can be controlled by external stimuli is a fascinating and challenging topic for supramolecular chemists. The modification of photochromic molecules with noncovalent interaction sites or the incorporation of photochromic molecules into self-assembling modules makes light an ideal external input, providing high-performance photoresponsive multicomponent self-assemblies. Among such systems, in this tutorial review we deal with several photoresponsive supramolecular self-assemblies showing a unique mechanism and/or type of photoresponse. These examples illustrate that we would be able to produce further new photoresponsive molecular ensembles if one can elaborately hybridize photochromic molecules to specifically-designed supramolecular self-assemblies. We believe that the accumulation of insight into the construction principle, mechanism and concept of such smart supramolecular self-assemblies should realize practical smart functional materials.