共晶工程的颜色和形态调控

共晶工程作为化学材料的重要研究手段之一,在光电学、药学等多个领域取得了不同的研究进展与成果。与传统合成方法相比,共晶可通过简便、低成本的操作实现共晶组件的多功能性,同时通过微观调控实现共晶形态、结构乃至颜色的调节。本综述首先介绍了共晶的分类和制备,然后介绍了有机电荷转移共晶发光材料、机械变色发光材料的荧光颜色调控以及药物共晶、有机光电功能共晶的颜色调控;其次,介绍了外部内部因素对晶体形态调控的影响;最后,介绍了共晶晶体多态性和荧光色彩之间的关系以及共晶材料的未来发展。希望本文可以为共晶材料颜色和形态方面的优化与改善提供一定的思路,也为其他化学材料的质量优化提供借鉴意义。     

Intermolecular Charge-Transfer Interactions Facilitate Two-Photon Absorption in Styrylpyridine–Tetracyanobenzene Cocrystals

Cocrystals of 4-styrylpyridine and 1,2,4,5-tetracyanobenzene were successfully prepared by supramolecular self-assembly. Donor–acceptor interactions between the molecular components are the main driving force for self-assembly and contribute to intermolecular charge transfer. The cocrystals possess two-photon absorption properties that are not observed in the individual components; suggesting that two-photon absorption originates from intermolecular charge-transfer interactions in the donor–acceptor system. The origin of two-photon absorption in multichromophore systems remains under-researched; thus, the system offers a rare demonstration of two-photon absorption by cocrystallization. Cocrystal engineering may facilitate further design and development of novel materials for nonlinear optical and optoelectronic applications.     

Intermolecular Charge‐Transfer Interactions Facilitate Two‐Photon Absorption in Styrylpyridine–Tetracyanobenzene Cocrystals

Cocrystals of 4‐styrylpyridine and 1,2,4,5‐tetracyanobenzene were successfully prepared by supramolecular self‐assembly. Donor–acceptor interactions between the molecular components are the main driving force for self‐assembly and contribute to intermolecular charge transfer. The cocrystals possess two‐photon absorption properties that are not observed in the individual components; suggesting that two‐photon absorption originates from intermolecular charge‐transfer interactions in the donor–acceptor system. The origin of two‐photon absorption in multichromophore systems remains under‐researched; thus, the system offers a rare demonstration of two‐photon absorption by cocrystallization. Cocrystal engineering may facilitate further design and development of novel materials for nonlinear optical and optoelectronic applications.     

Two-dimensional materials toward Terahertz optoelectronic device applications

Two-dimensional (2D) materials have become a worldwide hot topic due to their fascinating properties, including high carrier mobility, tunable bandgap, ultra-broadband optical absorption and response. The versatility of 2D materials enable it hold great potential to achieve high performance Terahertz (THz) optoelectronic devices. However, the THz radiation, range from infrared to microwave, known as the THz gap, much less investigated than that of other electromagnetic wave. Motivated by this lack of knowledge, we reviewed the recent advances of research into 2D materials based THz optoelectronic devices. Firstly, we introduced the background and motivation of this review. Then, the suitable 2D material candidates are exhibited, followed by a comprehensive review of their applications in THz generation devices, modulator, THz shielding, and photodetectors. Finally, the challenges and further development directions are concluded. We believe that some milestone investigations of 2D materials based THz optoelectronic devices will emerge soon, which will bring about great industrial revelations in 2D materials-based nanodevice commercialization.     

Organic white-light sources: multiscale construction of organic luminescent materials from molecular to macroscopic level

Organic luminescent materials play an integral role in the optoelectronic applications of displays and solid-state lighting. Nevertheless, high-performance organic luminescent materials require the efficient combination of two or more kinds of materials, which is extremely difficult owing to the completely different self-assembly behaviors of multicomponent molecules. Herein, based on a broad scale from the molecular, micro-/nano-scale, and macroscopic levels, we successfully demonstrate the multiscale construction of organic luminescent microwires of cocrystals, solid solutions, and core-shell microstructures. Through the wide selection of electron donor/acceptor pairs, a series of color-tunable charge-transfer (CT) cocrystals are formed via the intermolecular cooperative self-assembly process. On this basis, the high structural compatibility and perfect lattice mismatching (～1.1%) of cocrystals are critical factors that facilitate the combination of dissimilar materials to form solid solutions and core/shell microwires. Significantly, because of the full-spectrum light transport from 400 to 800 nm, the nano-micro-scaled solid solution microwires act as microscale white-light sources [CIE (0.32, 0.36)]. Meanwhile, the macroscopic-scale core/shell organic-microwires demonstrate tunable white-light emission with a high color-rendering index (CRI) of 83, whose CIE coordinates span from (0.37,0.39) to (0.40,0.31). Therefore, our work provides a feasible approach to the multiscale synthesis of novel luminescent organic semiconductor materials, which could lay a solid foundation for organic optoelectronics.

     

Identification of an Overlooked Halogen-Bond Synthon and Its Application in Designing Fluorescent Materials

Research on new supramolecular synthons facilitates the progress of materials design. Herein, the ability of sp² carbonyl oxygen atoms to act as halogen-bond acceptors was established through cocrystallization. Four sets of carbonyl compounds, including aldehydes, ketones, esters, and amides, were selected as halogen-bond acceptors. In the absence of strong hydrogen bonds, 14 out of 16 combinations of halogen-bond donors and acceptors could form cocrystals, whereby the supramolecular synthon C=O ⋅⋅⋅ X acts as the main interaction. Further, the geometric parameters of the C=O ⋅⋅⋅ X interaction were statistically revealed on the basis of the crystallographic database. The bifurcated interaction mode that has been observed in other halogen-bond synthons rarely occurs in the case of C=O ⋅⋅⋅ X. The robustness of C=O ⋅⋅⋅ X makes its application in crystal engineering possible and opens up new opportunities in designing multicomponent fluorescent materials, as indicated by multicolor emission of cocrystals D through C=O ⋅⋅⋅ X interactions.     

Excited states of TAPT-PDA COF spectra based on first principles and quantum chemical calculations

Improving two-dimensional (2D) materials is crucial for achieving integrated, intelligent, and multifunctional development of optoelectronic materials. Thus, it is essential to have a comprehensive understanding of the excitation mechanisms of covalent organic framework (COF) materials in order to prepare and modify 2D materials. This study focuses primarily on the optoelectronic properties of TAPT-PDA COF. First, the geometric structure of TAPT-PDA COF, which has a pore size of 32.4 Å and a width of 1.75 Å, was determined using first principles and quantum chemical methods. Second, the hole–electron distribution of each excited state of TAPT-PDA COF was analyzed for oscillator strengths exceeding 0.01. Additionally, the electron transition mechanism for each excited state following photon absorption was investigated. Finally, the study presents the UV–Vis and electronic circular dichroism spectra of TAPT-PDA COF based on quantitative calculations. To validate the results, the chirality of TAPT-PDA COF was experimentally confirmed. The graphs and data obtained from the experiments demonstrate that TAPT-PDA COF exhibits excellent optoelectronic performance and has significant potential for application in optoelectronic devices.     

Ultrasound‐Assisted Construction of Halogen‐Bonded Nanosized Cocrystals That Exhibit Thermosensitive Luminescence

Multi‐component organic nanocrystals that are comprised of two or more supramolecular building blocks can be used to extend the design and assembly scope of solid molecular materials. Herein, we report the use of ultrasonication to prepare halogen‐bonded stilbene‐based nano‐cocrystals that exhibit different photoemission properties, including one‐ and two‐phonon emission and fluorescence lifetimes, relative to those of macrodimensional crystals. The structural transformation from nano‐cocrystals into nanocrystals upon heating results in a luminescence red‐shift from greenish blue to yellow. The temperature‐dependent ratiometric luminescence may allow such nano‐cocrystals to be used as fluorescent sensors and thermosensitive materials.     

Selective formation of luminescent chiral cocrystal: Molecular self-assembly of 2,2′-binaphthol and 2-(3-pyridyl)-1H-benzimidazole

Luminescent chiral cocrystal based on the self-assembly of 2,2'-binaphthol and 2-(3-pyridyl)-1H-benzimidazole (P.) has been developed, in which 100% R configuration of BINOL can be obtained in the cocrystal products. The final structure presents the same P.R. The studies suggested that the cocrystallization approach could have much flexibility and potential applications for the design of chiral fluorescent materials.     

超分子化学在药物共晶中的应用

药物共晶是一种新兴的药物晶型, 一个给定的活性药物分子通过形成共晶, 一方面可以大大丰富其结晶形式, 另一方面可以改善其物化性质及临床疗效. 本文从超分子化学的角度对药物共晶进行了综述, 列举了一系列通过氢键超分子合成子进行药物共晶设计和制备的研究实例, 旨在促进超分子化学和药学的交叉融合.     

Unravelling the Correlation between Charge Mobility and Cocrystallization in Rod–Rod Block Copolymers for High‐Performance Field‐Effect Transistors

Cocrystallization involving two or more components aggregating into cocrystals allows the preparation of materials with markedly improved charge mobility. This approach however, is little explored in all‐conjugated block copolymers (BCPs). Herein, we report the first investigation into the correlation between cocrystals and charge mobility in a series of new all‐conjugated BCPs: poly(3‐butylthiophene)‐b‐poly(3‐hexylselenophene) (P3BT‐b‐P3HS) for high‐performance field‐effect transistors. These rationally synthesized rod–rod BCPs self‐assemble into cocrystals with high charge mobilities. Upon one‐step thermal annealing, their charge mobilities decrease slightly despite their increased crystallinities. After two‐step thermal annealing, P3BT‐b‐P3HS (P3BT/P3HS=2:1) and (1:1) cocrystals disappear and phase separation occurs, leading to greatly decreased charge mobilities. In contrast, P3BT‐b‐P3HS (1:2) retains its cocrystalline structure and its charge mobility.     

范德华外延生长硫化镉二维纳米片及其光致发光性能研究

二维纳米材料具有独特的结构和优异的性能,在电子学及光电子学领域有广泛的应用前景,但关于硫化镉二维纳米材料的制备及性能研究还鲜有报道。本文首次采用范德华外延生长技术,在氟金云母片衬底上制备了硫化镉二维纳米片。通过扫描电子显微镜、透射电子显微镜、原子力显微镜、X射线粉末衍射仪和拉曼光谱仪等分析手段对产物的形貌、厚度、晶体结构、成分等进行了系统的研究。结果表明,纳米片具有六方纤锌矿晶体结构,尺寸约为几个微米,厚度约为几十纳米。范德华外延生长技术在硫化镉二维单晶纳米片制备上的成功应用,为其它二维非层状材料的制备提供了新的思路,并使其在高性能电子和光电子器件上的应用成为了可能。     

Synthesis and Non-linear Optical（NLO） Properties of a Series of Alkoxysilane Derivative Chromophores

1 Introduction Nonlinear optical materials(NLO) have drawn a great intrest of some scholars and scientists in the last dacades because of their tremendous     

Controlled self-assembly of alkylated-π compounds for soft materials — Towards optical and optoelectronic applications

Organic and polymeric molecules based on π-conjugated units represent an important class of components for optical and optoelectronic functionalized soft materials. Inspired by the innovative molecular design made by synthetic chemists, new functions and applications of π-conjugated molecules are continuously emerging. However, a challenge that remains is to soften these molecules. Alkylation is a commonly employed synthetic strategy to achieve functionalization in order to improve processability, i.e., solubility in volatile solvents, for better utilization in the rapidly-developing field of organic electronics. In addition it is recognized as a powerful strategy to tune the interaction among the π-conjugated moieties. In a different interpretation of alkylation, alkylated-π compounds can be viewed as a class of hydrophobic amphiphiles, since the rigid π-conjugated moiety and flexible alkyl chains are intrinsically immiscible. Recent studies have shown that such compounds can form a variety of self-organized solid and thermotropic liquid crystalline structures as well as nonassembled liquid forms depending upon the position, number and kinds of attached alkyl chains. Here, we present a brief overview of recent developments of alkylated-π chemistry, with an emphasis on the relationships between molecular design, self-assembly behavior and applications in optical and optoelectronic devices. We hope this review can serve as a guide and reference for people working in different research areas, including self-assembly and colloid sciences, synthetic and materials chemistry was well as organic electronics.     

Uncovering the Intramolecular Emission and Tuning the Nonlinear Optical Properties of Organic Materials by Cocrystallization

The spectroscopic and photophysical properties of organic materials in the solid‐state are widely accepted as a result of their molecular packing structure and intermolecular interactions, such as J‐ and H‐aggregation, charge‐transfer (CT), excimer and exciplex. However, in this work, we show that Spe‐F₄DIB cocrystals (SFCs) surprisingly retain the energy levels of photoluminescence (PL) states of Spe crystals, despite a significantly altered molecular packing structure after cocrystallization. In comparison, Npe‐F₄DIB cocrystals (NFCs) with new spectroscopic states display different spectra and photophysical behaviors as compared with those of individual component crystals. These may be related to the molecular configuration in crystals, and we propose Spe as an “intramolecular emissive” material, thus providing a new viewpoint on light‐emitting species of organic chromophores. Moreover, the nonlinear optical (NLO) properties of Npe and Spe are firstly demonstrated and modulated by cocrystallization. The established “molecule‐packing‐property” relationship helps to rationally control the optical properties of organic materials through cocrystallization.     

Imide-Functionalized Polymer Semiconductors

Imide-functionalized π-conjugated polymer semiconductors have received a great deal of interest owing to their unique physicochemical properties and optoelectronic characteristics, including excellent solubility, highly planar backbones, widely tunable band gaps and energy levels of frontier molecular orbitals, and good film morphology. The organic electronics community has witnessed rapid expansion of the materials library and remarkable improvement in device performance recently. This review summarizes the development of imide-functionalized polymer semiconductors as well as their device performance in organic thin-film transistors and polymer solar cells, mainly achieved in the past three years. The materials mainly cover naphthalene diimide, perylene diimide, and bithiophene imide, and other imide-based polymer semiconductors are also discussed. The perspective offers our insights for developing new imide-functionalized building blocks and polymer semiconductors with optimized optoelectronic properties. We hope that this review will generate more research interest in the community to realize further improved device performance by developing new imide-functionalized polymer semiconductors.     

2D Organic Photonics: An Asymmetric Optical Waveguide in Self‐Assembled Halogen‐Bonded Cocrystals

Anisotropic organic molecular construction and packing are crucial for the optoelectronic properties of organic crystals. Two‐dimensional (2D) organic crystals with regular morphology and good photon confinement are potentially suitable for a chip‐scale planar photonics system. Herein, through the bottom‐up process, 2D halogen‐bonded DPEpe‐F₄DIB cocrystals were fabricated that exhibit an asymmetric optical waveguide with the optical‐loss coefficients of R_Backward=0.0346 dB μm^?1 and R_Forward=0.0894 dB μm^?1 along the [010] crystal direction, which can be attributed to the unidirectional total internal reflection caused by the anisotropic molecular packing mode. Based on this crystal direction‐oriented asymmetric photon transport, these as‐prepared 2D cocrystals have been demonstrated as a microscale optical logic gate with multiple input/out channels, which will offer potential applications as the 2D optical component for the integrated organic photonics.     

Plasticization and cocrystallization in LLDPE/wax blends

The structure and thermal properties of linear low‐density polyethylene (LLDPE)/medium soft paraffin wax blends, prepared by melt mixing, were investigated by differential scanning calorimetry (DSC) and small‐ and wide‐angle X‐ray scattering (SAXS and WAXS). The blends form a single phase in the melt as determined by SAXS. Upon cooling from the melt, two crystalline phases develop for blends with more than 10 wt % wax characterized by widely different melting points. The wax acts as an effective plasticizer for LLDPE, decreasing both its crystallization and melting temperature. The higher melting point crystalline phase is formed by less branched LLDPE fractions. On the other hand, the lower melting point crystalline phase is a wax‐rich phase constituted by cocrystals of extended chain wax and short linear sequences of highly branched LLDPE chains. The presence of cocrystals was evidenced by standard DSC results, successive self‐nucleation and annealing (SSA) thermal fractionation and by the detection of a new SAXS signal attributed to the lamellar long period of the cocrystals. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1469–1482     

Curved Oligophenylenes as Donors in Shape‐Persistent Donor–Acceptor Macrocycles with Solvatofluorochromic Properties

Many optoelectronic organic materials are based on donor–acceptor (D–A) systems with heteroatom‐containing electron donors. Herein, we introduce a new molecular design for all‐carbon curved oligoparaphenylenes as donors, which results in the generation of unique shape‐persistent D–A macrocycles. Two types of acceptor‐inserted cycloparaphenylenes were synthesized. These macrocycles display positive solvatofluorochromic properties owing to their D–A characteristics, which were confirmed by theoretical and electrochemical studies.