Isolation and characterization of a lipopeptide-producing Bacillus sp. strain JK08 with antagonistic activity against Vibrio parahaemolyticus.

AIMS: The present study aimed to isolate a potential antagonist Bacillus sp. and evaluate its capacity for controlling pathogenic Vibrio parahaemolyticus in aquaculture. METHODS AND RESULTS: Strain JK08, which showed inhibitory activity against V. parahaemolyticus VP02r, was isolated from a Penaeus vannamei pond. Based on morphological, physiological, and biochemical characteristics and phylogenetic analysis, strain JK08 was identified as Bacillus sp. Through culture condition optimization, the maximal inhibition zone diameter (18.19 ± 0.16 mm) was observed when strain JK08 was cultivated at a temperature of 30°C, pH of 7, and salinity of 20‰ in Luria-Bertani broth for 24 h. The inhibition zone against V. parahaemolyticus VP02r of strain JK08 (∼7 µg, in mass of crude antimicrobial substance, per tablet) was larger than those (14-18 mm in diameter) of several commercial antibiotics (10 µg per tablet) in the in vitro antagonism assay. Liquid chromatography-tandem mass spectrometry analysis results indicated the presence of three families of lipopeptides in the antimicrobial substance: surfactin (C12-C17), iturin A (C14-C17), and fengycin A (C14-C17) and B (C17), which might be the key components contributing to the antagonistic activity of strain JK08. CONCLUSIONS: Strain JK08, which is capable of producing antibacterial lipopeptides, shows effective antagonistic activity against V. parahaemolyticus VP02r, implying its promising potential for V. parahaemolyticus control in aquaculture.

Lignin-derived polyphenols with enhanced antioxidant activities by chemical demethylation and their structure-activity relationship.

Lignin valorization to biobased polyphenols antioxidants is increasingly attractive in the modern industry due to their inherent phenolic structures. Herein, lignin-derived polyphenols with enhanced antioxidant activities were prepared from the most available technical lignin including organosolv lignin (OL), alkali lignin (AL), and enzyme lignin (EL) by iodocyclohexane (ICH) chemical demethylation. The structural evolution of lignin indicated that the CAr-OCH3 group and the CAr-O-Calkyl side-chain could be effectively transformed into the CAr-OH group, resulting in a significant increase of the phenolic-OH content and a slight decrease of the molecular weight. The 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) scavenging activity was in the order of ICHOL-24 > ICHAL-24 > ICHEL-24 ≈ FA > BHT, and the IC50 value of ICHOL-24 was 0.56 times lower than that of BHT. The structure-activity relationship demonstrated the activities were quasi-linearly related to phenolic-OH contents and could be affected by molecular weights. The H/G/S proportions of lignin could be an indicator for accurate screening of efficient lignin-derived polyphenols antioxidants (LPA). It was preliminarily estimated to have economic feasibility for producing LPA from technical lignin by demethylation compared with synthetic or natural antioxidants. This work will help to develop efficient biobased antioxidants for lignin valorization.

Galanin family peptides: Molecular structure, expression and roles in the neuroendocrine axis and in the spinal cord.

Galanin is a neurohormone as well as a neurotransmitter and plays versatile physiological roles for the neuroendocrine axis, such as regulating food intake, insulin level and somatostatin release. It is expressed in the central nervous system, including hypothalamus, pituitary, and the spinal cord, and colocalises with other neuronal peptides within neurons. Structural analyses reveal that the human galanin precursor is 104 amino acid (aa) residues in length, consisting of a mature galanin peptide (aa 33-62), and galanin message-associated peptide (GMAP; aa 63-104) at the C-terminus. GMAP appears to exhibit distinctive biological effects on anti-fungal activity and the spinal flexor reflex. Galanin-like peptide (GALP) has a similar structure to galanin and acts as a hypothalamic neuropeptide to mediate metabolism and reproduction, food intake, and body weight. Alarin, a differentially spliced variant of GALP, is specifically involved in vasoactive effect in the skin and ganglionic differentiation in neuroblastic tumors. Dysregulation of galanin, GALP and alarin has been implicated in various neuroendocrine conditions such as nociception, Alzheimer's disease, seizures, eating disorders, alcoholism, diabetes, and spinal cord conditions. Further delineation of the common and distinctive effects and mechanisms of various types of galanin family proteins could facilitate the design of therapeutic approaches for neuroendocrine diseases and spinal cord injury.

Hydroxy-Modified Hierarchical Porous Na-CoOx /CN Material for Low-Concentration High-Throughput Formaldehyde Oxidation at Room Temperature.

Engineering the pore structure and surface properties of the catalyst are the key to realizing the highly efficient conversion of low-concentration and high-throughput formaldehyde at room temperature. Herein, alkali-modified hierarchical porous Na-CoOx /CN material was prepared using a novel freeze-drying-pyrolysis method by employing super absorbent resin/MOF composites as templates, which generate mesopores distributed in a narrow region of 6∼20 nm and abundant hydroxyl groups on the surface by alkali-modification. At room temperature, the Na-CoOx /CN material exhibited full conversion of low concentration (1.0 mg/m3 ) and high throughput (240,000 mL/(gcat h)) formaldehyde while also demonstrating outstanding catalytic stability under a even higher space velocity (480,000 mL/(gcat h)). In situ DRIFTS characterization revealed that the hydroxyl groups on the catalyst's surface could be consumed by oxidizing formaldehyde to intermediate species (carbonate, hydrocarbonate), which were then regenerated by Na+ and CO3 2- , contributing to the cycle of the reaction path.

Molecular Structure, Expression and Role of TAFA4 and its Receptor FPR1 in the Spinal Cord.

TAFA chemokine like family member 4 (TAFA4, also named FAM19A4) is a member of the TAFA chemokine like ligand or FAM19A family, which includes TAFA1, TAFA2, TAFA3, TAFA4, and TAFA5 (or FAM19A1, FAM19A2, FAM19A3, FAM19A4, and FAM19A5). They are also referred to as neurokines and are involved in the regulation of a diverse range of cellular processes, including chemotaxis of macrophages, phagocytosis, and release of reactive oxygen species (ROS). TAFA4 is a marker of C-low-threshold mechanoreceptors and is expressed predominantly in nociceptors, such as dorsal root ganglia (DRG). TAFA4 has been implicated in the sensory perception of pain in the spinal cord. Mice with deficiency of TAFA4 demonstrate altered excitability in lamina IIi neurons in DRG in addition to increased mechanical and chemical nociception following inflammation or injury. As a secreted protein, TAFA4 binds to cell surface receptor formyl peptide receptor 1 (FPR1), a G protein-coupled receptor to mediate the chemoattraction of macrophages, phagocytosis, and the inflammatory profile of macrophages. It also interacts with cell surface neurexin to mediate signalling across the synapse. Further understanding the mechanisms by which this conserved protein family regulates diverse biological processes such as in neuronal functions, inflammation, and tissue fibrosis will help to design therapeutic targets for the treatment of TAFA related diseases such as spinal cord injury and neuro-inflammatory disorders.

Light-induced facile and efficient synthesis of color-variable lignin-based gold nanoparticles and its application as Pb2+ sensor.

The sustainable synthesis of gold nanoparticles (AuNPs) is widely exploited. However, the preparation of color-variable AuNPs based on renewable energy had not been reported. Here, a facile approach to synthesis color-variable lignin-based AuNPs was presented for the first time, using UV-induced decomposition of Au2O3 as the gold precursor and lignin as the stabilizer for AuNPs in dimethyl sulfoxide solvent. UV radiation technology could effectively convert Au3+ into Au0. In addition, the reaction behavior was systematically studied, and the conversion rate and reaction rate of Au2O3 could be further enhanced by changing the temperature. More interestingly, the aggregation degree of AuNPs could be adjusted by changing the amount of lignin, and the color-variable AuNPs from wine red to purple was realized. At the same time, the lignin-functionalized AuNPs showed high selectivity as the colorimetric detector towards Pb2+ ions. Our work displayed a facile, nontoxic and efficient method to prepare color-variable AuNPs, which might provide a realizable perspective to the colorimetric and sensing of AuNPs.

The Molecular Structure and Role of Humanin in Neural and Skeletal Diseases, and in Tissue Regeneration.

Humanin (HN) belongs to a member of mitochondrial-derived peptides (MDPs) which are encoded by mitochondrial genes. HN shares sequence homology with thirteen HN-like proteins, named MTRNR2L1 to MTRNR2L13, which encompass 24-28 amino acid residues in length. HN mediates mitochondrial status and cell survival by acting via an intracellular mechanism, or as a secreted factor via extracellular signals. Intracellularly, it binds Bcl2-associated X protein (BAX), Bim and tBid, and IGFBP3 to inhibit caspase activity and cell apoptosis. When released from cells as a secreted peptide, HN interacts with G protein-coupled formyl peptide receptor-like 1 (FPRL1/2) to mediate apoptosis signal-regulating kinase (ASK) and c-Jun N-terminal kinase (JNK) signalling pathways. Additionally, it interacts with CNTFR-α/gp130/WSX-1 trimeric receptors to induce JAK2/STA3 signalling cascades. HN also binds soluble extracellular proteins such as VSTM2L and IGFBP3 to modulate cytoprotection. It is reported that HN plays a role in neuronal disorders such as Alzheimer's disease, as well as in diabetes mellitus, infertility, and cardiac diseases. Its roles in the skeletal system are emerging, where it appears to be involved with the regulation of osteoclasts, osteoblasts, and chondrocytes. Understanding the molecular structure and role of HN in neural and skeletal diseases is vital to the application of HN in tissue regeneration.

Electroinduced Reconfiguration of Complex Emulsions for Fabrication of Polymer Particles with Tunable Morphology.

Continuous morphological control of anisotropic particles is always an important challenge in the field of materials. In this study, a new strategy for continuous fabrication of polymer particles with various morphologies induced by electricity is reported using complex emulsions as template. A synthetic electro-responsive surfactant containing ferrocene group is used to prepare complex emulsions, which contain a polymerizable monomer as inner phase. With the increasing time of electrical stimulation on the complex emulsions, hollow, hemispherical, mushroom-like, and spherical particles are constructed successively after photopolymerization. The Marangoni effect caused by the heterogeneity in the interfacial tension at the droplet surface is the reason for the reconfigurable morphology of the complex emulsion. The controllable complex emulsions by electricity present a versatile platform for constructing fine control of the microstructure and shape anisotropy of particles having customized shapes and functionalities, opening a new possibility for designing sophisticated architectures.

A high-precision thermometry microfluidic chip for real-time monitoring of the physiological process of live tumour cells.

Temperature changes in cells are generally accompanied by physiological processes. Cellular temperature measurements can provide important information to fully understand cellular mechanisms. However, temperature measurements with conventional methods, such as fluorescent polymeric thermometers and thermocouples, have limitations of low sensitivity or cell state disturbance. We developed a microfluidic chip integrating a high-precision platinum (Pt) thermo-sensor that can culture cells and monitor the cellular temperature in situ. During detection, a constant temperature system with a stability of 0.015 °C was applied. The temperature coefficient of resistance of the Pt thermo-sensor was 2090 ppm/°C, giving a temperature resolution of the sensor of less than 0.008 °C. This microchip showed a good linear correlation between the temperature and resistance of the Pt sensor at 20-40 °C (R2 = 0.999). Lung and liver cancer cells on the microchip grew normally and continuously. The maximum temperature fluctuation of H1975 (0.924 °C) was larger than that of HepG2 (0.250 °C). However, the temperature of adherent HepG2 cells changed over time, showing susceptibility to the environment most of the time compared to H1975. Moreover, the temperature increment of non-cancerous cells, such as hepatic stellate cells, was monitored in response to the stimulus of paraformaldehyde, showing the process of cell death. Therefore, this thermometric microchip integrated with cell culture could be a non-disposable and label-free tool for monitoring cellular temperature applied to the study of physiology and pathology.

pH-Responsive Pickering emulsions stabilized solely by surface-inactive nanoparticles via an unconventional stabilization mechanism.

Using solely highly hydrophilic particles to stabilize emulsions, especially high internal phase emulsions, has always been an important challenge. Here pH-responsive Pickering emulsions stabilized by a low concentration of bare highly hydrophilic Ludox CL nanoparticles without surface modification or addition of surfactants are developed at neutral pH. The dispersed nanoparticles can be transformed into an aggregate state with a network-like structure near the isoelectric point, which contributes to the stabilization of the emulsions. Moreover, the vdW attraction between particles and droplets also plays a key role in the formation of emulsions, which can make the aggregated nanoparticles adsorb tightly around the droplets rather than penetrate the oil-water interface. The formed protective armor and network-like aggregates separate droplets from each other to prevent coalescence. At a low nanoparticle concentration (0.5 wt%), a high internal phase emulsion can be formed and can last up to half a year. This system can emulsify not only the hydrocarbon oil but also the fluoroalkane oil phase. Finally, organic-inorganic composite particles are fabricated using the template action of the Pickering emulsions. The method of preparing composite particles is more convenient than the traditional Pickering emulsion polymerization which often requires the modification of the surface of the hydrophilic particles or the addition of auxiliary monomers. This study provides a simple green strategy for the preparation of a more stable Pickering emulsion stabilized by surface-inactive nanoparticles and will broaden the scope of applications.

A batch microfabrication of a microfluidic electrochemical sensor for rapid chemical oxygen demand measurement.

Chemical oxygen demand (COD) is one of the key water quality parameters in environmental monitoring. However, fabricating a COD sensor with the characteristic of batch-processing and rapid measurement is always a challenging issue. This paper reports a microfluidic electrochemical sensor for the organic matter measurement based on advanced oxidization within a fixed microvolume detection chamber by a microfabrication technique/MEMS. By fabricating a silicon-based Ag/AgCl reference electrode and employing PbO2 as the working electrode with Pt as the counter electrode, we verified the superiority of the as-fabricated sensor by continuous potassium acid phthalate detection; an acceptable limit of detection (4.17 mg L-1-200 mg L-1), a low limit of detection (2.05 mg L-1), a desirable linearity (R2 = 0.982) and relative stability at different pH values and Cl- concentrations was witnessed. Particularly, a shorter detection time (2 s) was witnessed for the as-proposed sensor compared with traditional organic matter measurement methods. Each sensing process takes only 2 seconds for sensing because a micro-cavity with a volume of 2.5 µL was fabricated and used as a detection pool. Moreover, as the sensor was fabricated by a mass-production technique, potential response consistency of multiple sensors was expected and was verified via a series of parallel experiments. In this paper, a miniaturized (8 mm × 10 mm), low-cost and reliable COD sensor was designed and fabricated by MEMS, and it provided a core sensor component for construction of an online water environment monitoring network to meet the substantial demand for COD sensors in the Internet of Things (IOT) era.

Design, Synthesis, Biological Evaluation and Inhibition Mechanism of 3-/4-Alkoxy Phenylethylidenethiosemicarbazides as New, Potent and Safe Tyrosinase Inhibitors.

Tyrosinase plays important roles in many different disease related processes, and the development of its inhibitors is particularly important in biotechnology. In this study, thirty-nine 3-/4-alkoxyphenylethylidenethiosemicarbazides were synthesized as novel tyrosinase inhibitors based on structure-based molecular design. Our experimental results demonstrated that thirty-one of them possess remarkable tyrosinase inhibitory activities with IC50 value below 1 µM, and 5a, 6e, 6g and 6t did not display any toxicity to 293T cell line at the concentration of 1000 µmol/L. According to the inhibitory activities, several compounds were selected for detail investigation on the structure-activity relationships (SARs), mechanisms of enzyme inhibition, inhibitory kinetics and cytotoxicity. In particular, the interaction between the selected inhibitors and the active center of tyrosinase was considered and discussed in detail based on their structural characteristics. Taken together, the results presented here demonstrated that the newly designed compounds are promising candidates for the treatment of tyrosinase-related disorders and further development of them may have significant contribution in biomedical science.

A lignin-biochar with high oxygen-containing groups for adsorbing lead ion prepared by simultaneous oxidization and carbonization.

A lignin-biochar with high acidic oxygen-containing groups was produced via a facile simultaneous oxidization and carbonization of pulping lignin by using sulfuric acid for the first time. The lignin-biochars were investigated by 13C NMR, FTIR and XPS, and results demonstrated that treatment by sulfuric acid could oxidize part of aromatic ring side chain to introduce high acidic oxygen-containing group, especially carboxyl group. Their total acidic oxygen-containing groups of lignin-biochar including COOH and Ar-OH reached 8.64 mmol/g. Adsorption experiments were carried and the maximum adsorption capacity of lignin-biochar for Pb2+ reached 679 mg/g, which was significantly higher than other lignin-based or carbon adsorbents. Moreover, it could maintain high removal rate at high adsorption capacity. It also demonstrated that adsorption capability was proportional to the accessible carboxyl groups.

Effect of Thermal Conductive Fillers on the Flame Retardancy, Thermal Conductivity, and Thermal Behavior of Flame-Retardant and Thermal Conductive Polyamide 6.

In this work, polyamide 6 (PA6) composites with improved flame retardancy and thermal conductivity were prepared with different thermal conductive fillers (TC fillers) such as aluminum nitride (AlN) and boron nitride (BN) in a PA6 matrix with aluminum diethylphosphinate (AlPi) as a fire retardant. The resultant halogen-free flame retardant (HFFR) and thermal conductive (TC) PA6 (HFFR-TC-PA6) were investigated in detail with a mechanical property test, a limiting oxygen index (LOI), the vertical burning test (UL-94), a cone calorimeter, a thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of the impact fracture surface and char residue of the composites were analyzed by scanning electron microscopy (SEM). It was found that the thermal conductivity of the HFFR-TC-PA6 composite increased with the amount of TC fillers. The TC fillers exerted a positive effect for flame retardant PA6. For example, the HFFR-TC-PA6 composites with the thickness of 1.6 mm successfully passed the UL-94 V-0 rating with an LOI of more than 29% when the loading amount of AlN-550RFS, BN-SW08 and BN-NW04 was 30 wt%. The morphological structures of the char residues revealed that TC fillers formed a highly integrated char layer surface (without holes) during the combustion process, as compared to that of flame retardant PA6/AlPi composites. In addition, the thermal stability and crystallization behavior of the composites were studied.

A Novel Nitrite-Base Aerobic Denitrifying Bacterium Acinetobacter sp. YT03 and Its Transcriptome Analysis.

Nitrite in a water environment is very harmful to humans and aquatic animals. A novel aerobic denitrifying bacterium able to utilize NO 2 - -N as the only nitrogen source was isolated for the purpose of removing nitrite from water, which was identified as Acinetobacter sp. and named as YT03. The growth and denitrification activity of strain YT03 was assessed comprehensively. Results showed that the nitrite in water with an initial concentration of 10 mg L-1 could be completely removed within 6 h by strain YT03, and the optimal conditions for strain YT03 to remove nitrite were as follows: sodium succinate as the carbon source, C/N ratio of 16, pH of 6.5, temperature of 30°C, and shaking speed of 250 rpm. An RNA-Seq transcriptome analysis was used to find genes associated with nitrite removal. Compared with the removal of ammonia nitrogen, 47 genes were significantly differentially expressed, including 20 up-regulated and 27 down-regulated genes, mainly involved in the transport process, biosynthetic process, and so on. And among the differentially expressed genes, C4-dicarboxylate transporter (DctA) and nitrate/nitrite transporter (Nrt) might be of importance for the efficient utilization of carbon and nitrogen sources in aerobic nitrite denitrification with sodium succinate by strain YT03.

Polypropylene Glycol-Polyoxytetramethylene Glycol Multiblock Copolymers with High Molecular Weight: Synthesis, Characterization, and Silanization.

The high crystallization at room temperature and high cost of polyoxytetramethylene glycol (PTMG) have become obstacles to its application. To overcome these problems, a segment of PTMG can be incorporated into a block copolymer. In this work, polypropylene (PPO) glycol-polyoxytetramethylene (PPO-PTMG) multiblock copolymers were designed and synthesized through a chain extension between hydroxyl (OH)-terminated PPO and PTMG oligomers. The chain extenders, feed ratios of the catalyst/chain extender/OH groups, reaction temperature, and time were optimized several times to obtain a PPO-PTMG with low crystallization and high molecular weight. Multiblock copolymers with low crystallization and high average molecular weight (Mn = 1.0-1.4 × 104 Dalton) were harvested using m-phthaloyl chloride as the chain extender. The OH-terminated PPO-PTMG multiblock copolymer with high Mn and a functionality near two was further siliconized by 3-isocyanatopropyltrimethoxysilane to synthesize a novel silyl-terminated polyether. This polyether has an appropriate vulcanizing property and potential applications in sealants/adhesive fields.

Selective Enrichment of Clenbuterol onto Molecularly Imprinted Polymer Microspheres with Tailor-made Structure and Oxygen Functionalities.

The noxious clenbuterol misapplied as the feed additive has posed an enormous threat to humans who actively rely on the food chains with high potential of contamination by clenbuterol, such as pork and beef. It is, therefore, highly desirable to develop novel materials and strategies for dealing with the clenbuterol. Herein, functional polymer microspheres prepared by Pickering emulsion polymerization were explored for the selective enrichment of the clenbuterol, and their structure and oxygen functionalities could be tailor-made by a molecular imprinting process. The clenbuterol imprinting was adequately demonstrated to not only increase the particle size (~52 nm vs. ~42 nm) and create cavities for the accommodation of the clenbuterol molecules, but also reduce the oxygen functionalities of the resulting molecularly imprinted polymer microspheres (MIPMs) by approximately 4 at.%, which is believed to correlate with the high specificity of the MIPMs. Various characterization methods were employed to evidence these findings, including scanning electron microscopy, BET measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental mapping examination. More importantly, the MIPMs showed a markedly superior enrichment capability towards clenbuterol to the counterpart, that is, non-molecularly imprinted polymer microspheres (NIPMs). Compared to the NIPMs without specificity for clenbuterol, the MIPMs exhibited an impressive selectivity to clenbuterol, with the relative selectivity coefficient (k') values largely exceeding 1, thus corroborating that the useful molecular imprinting led to the generation of the binding sites complementary to the clenbuterol molecule in the size and functionalities. The MIPMs were also employed as the stationary phase to fabricate molecularly imprinting solid-phase extraction column, and the spike recovery was demonstrated to be not significantly decreased even after nine cycles. Furthermore, the reliability of the method was also evidenced through the comparison of the MIPMs prepared from different batches.

Photoinduced Reconfiguration of Complex Emulsions Using a Photoresponsive Surfactant.

Photoresponsive complex emulsions are prepared in a three-phase system consisting of two oils: hexane (H) and perfluorooctane (F). An aqueous solution of a mixed surfactant of fluorosurfactant, F(CF2) x(CH2CH2O) yH (Zonyl FS-300), and a synthesized light-responsive surfactant, 2-(4-(4-butylphenyl)diazenylphenoxy)ethyltrimethylammonium bromide (C4AZOC2TAB) was employed as the continuous phase. Complex emulsions with various geometries were prepared by one-step vortex mixing and a temperature-induced phase-separation method. It was noticed that the topology of the complex emulsion was highly dependent on the mass ratio of Zonyl FS-300/C4AZOC2TAB. Light microscopy images showed that phase inversion from an H/F/W- to an F/H/W-type double emulsion via a Janus emulsion was achieved by gradually increasing the mass ratio of C4AZOC2TAB/Zonyl FS-300. Upon UV/blue light irradiation, the topology of complex emulsions was turned to switch from an F/H/W double emulsion to a Janus emulsion to an entirely inverted H/F/W double emulsion. Dynamic interfacial tension measurements showed that UV irradiation of the interface between an aqueous trans-C4AZOC2TAB solution and hexane brings about an increase in the interfacial tension, suggesting the nature of photoinduced morphological changes in complex emulsions. The reconfiguration process of complex emulsions was illustrated by the Marangoni effect based on heterogeneity in the interfacial tension at the complex emulsion surface induced by controlling the molecular conversion of C4AZOC2TAB using light irradiation. Finally, we used the complex emulsions structure to form an on-off switch to start and shut off the evaporation of one volatile phase to achieve process monitoring. This could be used to initiate and quench a reaction, which offers a novel idea for achieving switchable and reversible reaction control in multiple-phase reactions.

LED based on alternating benzene-furan oligomers.

A series of conjugated-chain compounds which contain two furan units and more than three other aromatic ring units were synthesized by two different methods, their UV-visible absorption coefficient (ε), maximum absorption wavelengths (λa), fluorescence emission wavelengths (λe), stokes shift and quantum yields (Φ) were determined, the relationships between the molecular structures and the effects of spectral behaviors were discussed. Meanwhile, the excitation spectrum and emission spectrum of 2b and 2d in solid and in ethyl acetate were respectively recorded, the thermal stability of 2b and 2d was evaluated, and the fluorescence emission behaviors of two light emitting diodes, fabricated with 2b and 2d as phosphors, were investigated. The results showed that most of target compounds can perform high fluorescence emission ability, compounds 2b and 2d can perform higher thermal stability under 350°C and they are suitable for making light emitting diode as phosphors, the light emitting diodes fabricated with 2b and 2d can show higher fluorescence emission ability. Therefore, those compounds are worthy of further being developed as fluorescent emission materials.

Synthesis and optical behaviors of 2-(9-phenanthrenyl)-, 2-(9-anthryl)-, and 2-(1-pyrenyl)-1-alkylimidazole homologues.

Eight 2-(9-phenanthrenyl)-, 2-(9-anthryl)- and 2-(1-pyrenyl)-1-alkyl-benzimidazole compounds, three 2-(9-anthryl)-1-alkylphenanthroimidazole compounds and five 4,5-diphenyl-1-alkyl-2-(9-anthryl)imidazole compounds were synthesized by alkylation reactions of the corresponding benzimidazole, phenanthroimidazole or imidazole compounds. 2-(10-Bromo-9-anthryl)-1-alkyl-benzimidazole compounds were prepared by bromination reaction of 2-(9-anthryl)-1-alkylbenzimidazole compounds. All the synthesized compounds were characterized by elemental analysis, (1)H NMR, (13)C NMR, MS or HRMS; their absorption coefficients (epsilon), maximum absorption lambda(amax), fluorescence emission maximum lambda(em), Stokes shifts and fluorescence quantum yields (Phi(F)) in ethyl acetate were determined; their fluorescent lifetimes (T(1) and T(2)) were measured in ethyl acetate and in solid state, respectively. The crystal structure of 2-(9-anthryl)-1-n-butyl-4,5-diphenylimidazole (12a) was determined to be triclinic, space group P-1 types, using single crystal X-ray crystallography technique. The results showed that these compounds exhibited moderate fluorescence-emission abilities and higher solubility in most organic solvents than their corresponding starting materials. The relationships between the optical behaviors and structures for these compounds were discussed.