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Low‐dielectric‐constant polymer materials are widely used in the electronic industry owing to their unique characteristics. Benzocyclobutene (BCB) resin is one such material with excellent dielectric properties and thermal stabilities. In this work, a novel BCB‐functionalized monomer (DCPDNO‐BCB) was synthesized from 2,6‐dimethyl phenol‐DCPD novolac (DCPDNO) and 4‐Bromobenzocyclobutene through Ullmann coupling. The structure of DCPDNO‐BCB was characterized by 1H NMR, 13C NMR, and ESI‐MS, and poly(DCPDNO‐BCB), obtained by ring‐opening and subsequent Diels–Alder reaction at the appropriate temperature, was found to exhibit low dielectric properties (k = 2.53 at 10 MHz), low water absorption, high thermal stability (Td5 = 430°C), and good film flatness. [ABSTRACT FROM AUTHOR]

Most benzocyclobutene (BCB) resins require a thermal pre-polymerization process to achieve the desired viscosity for application. However, the process is difficult to control because it is time-consuming and requires high temperatures. Therefore, a mild and simple method for preparing BCB based polysiloxane is proposed herein. Using a combination of the Heck reaction and hydrolytic condensation, linear BCB-based polysiloxane of various molecular weights can be routinely prepared by controlling the hydrolysis conditions. The obtained polymers have excellent dielectric properties (dielectric constants < 2.5 at 10 MHz) and thermal stability (T5 (the temperature of 5% weight loss) > 470 °C) after curing. [ABSTRACT FROM AUTHOR]

A benzocyclobutene (BCB) monomer containing carbosilane (CS‐BCB) was successfully synthesized from 4‐vinyl benzocyclobutene (4‐VBCB) and 3,6‐bis(dimethylsilyl)benzocyclobutene (3,6‐D(DMHS)BCB) by hydrosilylation in the presence of Karstedt's catalyst. As an improvement to the conventional synthesis method, the carbosilane is obtained in only two steps. In addition, this method avoids the use of halogens and Grignard reagents, which are expensive and environmentally damaging. After ring‐opening polymerization, the resultant cured CS‐BCB resin shows excellent thermal and dielectric properties; specifically, the 5 % weight loss temperature (T5%) is 435 °C, the dielectric constant (Dk) is 2.36, and the dielectric loss (Df) is less than 10−3 at 10 MHz. Thus, this polymer has enormous potential as a high‐performance electronic interlayer material. [ABSTRACT FROM AUTHOR]

[Objective] To establish methods to determine the content of Aconitine, Yunaconitine, Crassicauline and Vilmorrianine in Aconitun sungpanense Hand-Mazz. and provide scientific basis for its reasonable and safe application. [Methods] Aconitine, Yunaconitine, Crassicauline and Vilmorrianine were used as references. Phenomenex Gemini C18 110A (250 mm ×4.6 mm, 5 [μm); mobile phase; acetonitrile -0.2% acetic acid (pH was regulated to by triethylamine); gradient elute; flow rate; 1 mL/min; UV wavelength 235/254 nm; column temperature; 30 CC. [Results] The content of the 4 Ester-series alkaloids in Aconitun sungpanense Hand. -Mazz. could be determined at the same time. The average recovery rate (n = 6) of Aconitine, Yunaconitine, Crassicauline and Vilmorrianine reached 99. 65% (RSD = 1. 46%), 99. 13% (RSD = 1.32%), 98.13% (RSD =0.98%) and 98.66% (RSD = 1.67%). [Conclusions] The method was simple, accurate and had good repeatability. It could determine the content of Aconitine, Yunaconitine, Crassicauline and Vilmorrianine in Aconitun sungpanense Hand.-Mazz. at the same time. It also provided scientific basis for standardizing the processing of Aconitun sungpanense Hand. -Mazz. and its reasonable and safe application. [ABSTRACT FROM AUTHOR]

Chemical investigation for the secondary metabolite of marine-derived fungus Aspergillus sp. LS57 resulted in the isolation of one new chromone named aspergilluone A (1) containing a chromone skeleton fused with an unusual hydrogenation cyclopentanoid ring, along with three known compounds 2 – 4. The structure of 1 was elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analyses. Its absolute configuration was established by combining NMR quantum chemical calculations and comparison between the experimental and calculated circular dichroism (CD) curves. Additionally, the antibacterial assay of compound 1 was performed. As a result, compound 1 showed in vitro anti- Mycobacterium tuberculosis with MIC value of 32 μ g/mL, together with moderate antibacterial activity against Staphylococcus aureus (MIC values = 64 μ g/mL), and exhibited feeble activity against gram-positive Bacillus subtilis and gram-negative pathogen Escherichia coli (both MICs = 128 μ g/mL). [Display omitted] • One new antibacterial chromone aspergilluone A (1) containing a chromone skeleton fused with an unusual hydrogenation cyclopentanoid ring was isolated from a sponge-derived fungus Aspergillus sp. • Its absolute configuration was established by combining NMR quantum chemical calculations and comparison of the circular dichroism (CD) curves between the experimental and calculated. • Compound 1 exhibited inhibitory activities against Mycobacterium tuberculosis , Staphylococcus aureus , and Bacillus subtilis. [ABSTRACT FROM AUTHOR]