The study of elastic organic single crystals (EOSCs) has emerged as a cutting-edge research of crystal engineering. Although a few EOSCs have been reported recently, those suitable for optical/optoelectronic applications have not been realized. Here, we report an elastic crystal of a Schiff base, (E)-1-(4-(dimethylamino)phenyl)iminomethyl-2-hydroxyl-naphthalene. The crystal is highly bendable under external stress and able to regain immediately its original straight shape when the stress is released. It displays bright orange-red emission with a high fluorescence quantum yield of 0.43. Intriguingly, it can serve as a low-loss optical waveguide even at the highly bent state. Our result highlights the feature and utility of "elasticity" of organic crystals.

Thermally activated delayed fluorescence (TADF) materials that are able to realize electroluminescence showing simultaneously narrow emission band, high color purity, and high efficiency are highly demanded for display applications. Up to now, a few blue emissive TADF materials with such characteristics have been reported, while green TADF materials with such features are extremely scarce. Herein, two TADF compounds with highly efficient narrowband bluish green/green emission (full‐width at half‐maximum (FWHM): 22 and 21 nm in toluene) induced by multiple resonance effect are reported. An optimized organic light‐emitting diode based on the green emissive compound shows a fairly narrow electroluminescent spectrum (FWHM: 33 nm), as well as an excellent color purity with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.20, 0.65), which is a close resemblance to the standard green‐light CIE coordinates of (0.21, 0.71) defined by the National Television System Committee. Meanwhile, the maximum external quantum efficiency (EQE) up to 25.5% is achieved and a high EQE of 20.1% is maintained at a practical high luminance of 1000 cd m−2. The outstanding device performance of the compound makes it attractive for potential practical applications.

The design and synthesis of organic optical and electronic materials have attracted much attention because of their possible applications in organic electroluminescent devices (organic light-emitting diodes, OLEDs), organic thin-film transistors (OTFTs), and organic photovoltaic diodes (OPVDs). For solid organic materials, the constituent molecules may form strong intermolecular interactions and assemble into packed structures, with the result that the properties of these materials are governed by the whole collective rather than by individual molecules. [1][2][3][4][5][6][7] The performance of organic moleculebased devices strongly depends on the molecular-assembly structures. Therefore, understanding and controlling molecular arrangements in the solid state are fundamental issues for obtaining the desired chemical and physical properties of a material.[8] The increasing demand for new molecular organic functional materials requires the relationship between molecular packing characteristics and optical and electronic properties to be elucidated, which will enable the development of new strategies for developing high-performance organic materials. Although considerable progress has been made in organic luminescent materials with different molecular structures, [9][10][11][12][13][14][15][16][17][18][19][20][21] it is still essential to achieve a molecular-level understanding of the relationship between the molecular packing characteristics of organic materials and the resulting optical properties. [22][23][24][25][26] Hydrogen bonding and p_p stacking are two kinds of important intermolecular interactions for the construction of functional supramolecular systems. Furthermore, noncovalent intermolecular interactions such as hydrogen bonding, p_p interactions, and the presence of solvent molecules are all able to influence strongly the final packing structure, making polymorphism more probable. [27][28][29][30] Different polymorphs may have very different physical and chemical properties. The molecular assembly of optical and electronic materials based on the collective interactions of hydrogen bonding and p_p stacking remain a challenge in the field of organic functional materials.In this communication, we present methods of using the organic molecule 3(5)-(9-anthryl)pyrazole (ANP) (Scheme 1) as building blocks to construct different luminescent single crystals (polymorphs) based on hydrogen bonding and p_p stacking interactions. The relationship between the molecular packing and the optical properties of the obtained crystals are also reported.ANP was conveniently prepared in high yield from 9-acetylanthracene by a procedure analogous to the synthesis of other 3(5)-arylpyrazoles reported previously. [31,32] The absorption and emission spectra of ANP in chloroform solution are shown in Figure 1, and both the absorption and emission spectra exhibit the typical features of the anthracene chromophore. First, two kinds of ANP single crystals were grown by vacuum sublimation. ANP powder was heated to 433 K (±1.5 K) and...

R–Ph–B(FMes)2 compounds exhibit low reduction potentials, bright emission, a TICT state and unusual long-lived phosphorescence at low temperature.

Abstract:Three water-soluble tetracationic quadrupolar chromophores comprising two three-coordinate boron -acceptor groups bridged by thiophene-containing moieties were synthesised for biological imaging applications. The derivative 3 containing the bulkier 5-(3,5-Me2C6H2)-2,2′-(C4H2S)2-5′-(3,5-Me2C6H2) bridge is stable over a long period of time, exhibits a high fluorescence quantum yield and strong one-(OPA) and two-photon absorption (TPA), with a TPA cross-section of 268 GM at 800 nm in water. Confocal laser scanning fluorescence microscopy studies in live cells indicate localisation of the chromophore at the mitochondria; moreover, cytotoxicity measurements prove biocompatibilty. Thus, chromophore 3 has excellent potential for one-and two-photon excited fluorescence imaging of mitochondrial function in cells.

Flexible organic single crystals capable of plastic or elastic deformations have a variety of potential applications. Although the integration of plasticity and elasticity in a crystal is theoretically possible and it may cause rich and complex deformations which are highly demanded for potential applications, the integration is hard to realize in practice. Here, we show that through utilizing different modes of external forces for influencing molecular packing in different crystallographic directions, plastic helical twisting and elastic bending can both be achieved for a crystal, and they can even be realized simultaneously. Detailed crystallographic analyses and contrast experiments disclose the mechanisms behind these two kinds of distinct deformations and their mutual compatibility. Based on the plastically twistable nature of the crystal, a new application field of flexible organic single crystals, namely polarization rotators, is successfully opened up.

. (2015) 'DA triarylboron compounds with tunable pushpull character achieved by modication of both the donor and acceptor moieties.', Chemistry : a European journal., 21 (1). pp. 177-190. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

Boroles with a fluoromesityl group on the B atom have greatly improved air stability compared to their mesityl analogues.