Control of crystallinity of vinylene-linked two-dimensional conjugated polymers by rational monomer design

The interest in two-dimensional conjugated polymers (2D CPs) has increased significantly in recent years. In particular, vinylene-linked 2D CPs with fully in-plane sp2-carbon-conjugated structures, high thermal and chemical stability, have become the focus of attention. Although the Horner-Wadsworth-Emmons (HWE) reaction has been recently demonstrated in synthesizing vinylene-linked 2D CPs, it remains largely unexplored due to the challenge in synthesis. In this work, we reveal the control of crystallinity of 2D CPs during the solvothermal synthesis of 2D-poly(phenylene-quinoxaline-vinylene)s (2D-PPQVs) and 2D-poly(phenylene-vinylene)s through the HWE polycondensation. The employment of fluorinated phosphonates and rigid aldehyde building blocks is demonstrated as crucial factors in enhancing the crystallinity of the obtained 2D CPs. Density functional theory (DFT) calculations reveal the critical role of the fluorinated phosphonate in enhancing the reversibility of the (semi)reversible C−C single bond formation

Bridging the gap between molecular and elemental mass spectrometry: Higher energy collisional dissociation (HCD) revealing elemental information

Molecular mass spectrometry has been applied to simultaneously obtain molecular and elemental information from metal-containing species. Energy tuning of the higher-energy collision dissociation (HCD) fragmentation cell allows the controlled production of typical peptide fragments or elemental reporter ions informing about the metallic content of the analyzed species. Different instrumental configurations and fragmentation techniques have been tested, and the efficiency extracting the elemental information has been compared. HCD fragmentation operating at very high energy led to the best results. Platinum, lanthanides, and iodine reporter ions from peptides interacting with cisplatin, peptides labeled with lanthanides-MeCAT-IA, and iodinated peptides, respectively, were obtained. The possibility to produce abundant molecular and elemental ions in the same analysis simplifies the correlation between both signals and open pathways in metallomics studies enabling the specific tracking of metal-containing species. The proposed approach has been successfully applied to in solution standards and complex samples. Moreover, interesting preliminary MALDI-imaging experiments have been performed showing similar metal distribution compared to laser ablation (LA)-ICPMS

Screening of selenium containing proteins in the Tris-buffer soluble fraction of African catfish (Clarias gariepinus) fillets by laser ablation-ICP-MS after SDS-PAGE and electroblotting onto membranes

The anti-carcinogenic properties of selenium against certain types of cancer when present in organic forms justify the increasing interest in development of selenium fortified food. In this particular study, African catfish (Clarias gariepinus) were fed with a Se-enriched diet in order to enhance the selenium concentration in the fish fillet up to 0.85 ± 0.06 mg Se kg-1 (0.26 ± 0.02 mg Se kg-1 in control). Selenium distribution in proteins separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was studied for better understanding of the metabolism of this element in the organism. Soluble proteins (Tris buffer) were investigated by conventional application of a glass homogenizer in comparison to application of ultrasound probe sonication, and the latter was convincing due to higher protein extraction efficiency and the ease and speed of application. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was successfully applied for screening of selenium in proteins in fillets of African catfish separated by one-dimensional SDS-PAGE and after electroblotting onto nitrocellulose membranes, with a total Se amount below 0.4 ng loaded into a well. Selenium was detected in more than 11 protein spots. In order to improve the protein separation of one-dimensional SDS-PAGE, pre-fractionation of the Tris buffer soluble protein extract by size exclusion was carried out. Tryptic digestion of the Se-containing bands was performed for protein identification by nano-HPLC coupled to electrospray-MS/MS. A database search revealed several proteins which are located in muscle tissue. However, the very low Se concentration circumvents the detection of selenium containing amino acids in the tryptic peptides by electrospray-MS/M