Hierarchical Nanoarchitectonics of Ultrathin 2D Organic Nanosheets for Aqueous Processed Electroluminescent Devices.

Ultrathin 2D organic nanosheets (2DONs) with high mobility have received tremendous attention due to thickness of few molecular layers. However, ultrathin 2DONs with high luminescence efficiency and flexibility simultaneously are rarely reported. Here, the ultrathin 2DONs (thickness: 19 nm) through the modulation of tighter molecular packing (distance: ≈3.31 Å) achievable from the incorporation of methoxyl and dipenylamine (DPA) groups into 3D spirofluorenexanthene (SFX) building blocks is successfully prepared. Even with closer molecular stacking, ultrathin 2DONs still enable the suppression of aggregation quenching to exhibit higher quantum yields of blue emission (ΦF  = 48%) than that on amorphous film (ΦF  = 20%), and show amplified spontaneous emission (ASE) with a mediate threshold (332 mW cm-2 ). Further, through drop-casting method, the ultrathin 2DONs are self-organized into large-scale flexible 2DONs films (1.5 × 1.5 cm) with the low hardness (H: 0.008 Gpa) and low Young's modulus (Er : 0.63 Gpa). Impressively, the large-scale 2DONs film can realize electroluminescence performances with a maximum luminance (445 cd m-2 ) and low turn on voltage (3.7 V). These ultrathin 2DONs provide a new avenue for the realization of flexible electrically pumping lasers and intelligent quantum tunneling systems.

Regulating and Predicting the Polyhedral Crystal Morphology in Spirofluorene Molecular Systems.

Crystallization of organic steric molecules often leads to multiple polyhedral crystal morphologies. However, the relationships among the molecular structure, supramolecular interaction, aggregation mode and crystal morphology are still unclear. In this work, we elaborate two model crystals formed by spiro[fluorene-9,9'-xanthene] (SFX) and spiro[cyclopenta[1,2-b : 5,4-b']dipyridine-5,9'-xanthene] (SDAFX) to demonstrate the feasibility of morphology prediction by periodic bond chain (PBC) theory based on interaction energy (IE) values in terms of single point energy. With non-directional van der Waals forces, only one PBC direction is found in SFX crystal, leading to the irregular 1D rod-like structure. Compared with SFX, the extra N heteroatoms in SDAFX can bring additional hydrogen bonds and some other interactions into the bulky molecular skeletons, inducing 3-dimensionally oriented PBCs to form the explicit F-face network in SDAFX which leads to the final octahedral structure. A simple and accurate method has been provided to quantify PBC vector on the supramolecular level in the organic molecular system, and the PBC theory has also been further demonstrated and developed in the morphology prediction of organic spiro-molecules.

Supramolecular steric hindrance effect on morphologies and photophysical behaviors of spirocyclic aromatic hydrocarbon nanocrystals.

Three pyrene-based spirocyclic aromatic hydrocarbons (Py-SAHs) were prepared to clarify the roles of molecular segments in regulating the morphologies and photophysical properties of organic microcrystals. Due to the different supramolecular steric hindrance (SSH) effect between bulky groups and pyrene rings, distinct nanocrystal morphologies with unique photoluminescence properties were realized.

Jeotgalicoccus huakuii sp. nov., a halotolerant bacterium isolated from seaside soil.

A Gram-stain-positive, oxidase- and catalase-positive, non-motile, non-spore-forming, halotolerant, coccoid bacterium, designated strain NY-2(T), was isolated from a seaside soil sample from Shandong Province, China. Strain NY-2(T) was able to grow in the presence of 0-23 % (w/v) NaCl and at pH 4.5-10.0 and 5-42 degrees C; optimum growth was observed with 3-8 % (w/v) total salts and at pH 6.5-8.0 and 28-37 degrees C. Chemotaxonomic analyses, including fatty acid profiles, menaquinones and polar lipids, supported the affiliation of strain NY-2(T) to the genus Jeotgalicoccus. The predominant menaquinone of strain NY-2(T) was menaquinone 7 (MK-7) (100 %) and the major cellular fatty acids were iso-C(15 : 0) (49.0 %) and anteiso-C(15 : 0) (19.6 %). Cellular polar lipids were phosphatidylglycerol, diphosphatidylglycerol and several unidentified phospholipids. The DNA G+C content of strain NY-2(T) was 36.8 mol%. Based on 16S rRNA gene sequence analysis, strain NY-2(T) formed a coherent cluster with Jeotgalicoccus marinus JSM 076033(T), Jeotgalicoccus halotolerans YKJ-101(T) and Jeotgalicoccus psychrophilus YKJ-115(T). Phylogenetic analysis, DNA-DNA relatedness data, phenotypic characteristics and chemotaxonomic data indicated that strain NY-2(T) (=CCTCC AB 208288(T) =JCM 15687(T)) should be classified as the type strain of a novel species of the genus Jeotgalicoccus, for which the name Jeotgalicoccus huakuii sp. nov. is proposed.