Nitrogen-Based Linkers with a Mesitylene Core: Synthesis and Characterization

Mesitylene was used as a core in seven new tritopic nitrogen containing linkers. Three of the linkers, each containing three nitrile groups, were obtained through Suzuki, Sonogashira and Heck-type coupling reactions. Next, these were converted to tetrazol-5-yl moieties by the cycloaddition of sodium azide to the nitrile functionalities. The last linker, containing three 1,2,3-triazol-4-yl moieties, was synthesized by the Huisgen cycloaddition of phenyl azide to the corresponding alkyne. The latter was obtained via a Corey–Fuchs reaction sequence from the previously reported formyl derivative. As the proof of concept for their potential in MOF design, one of the nitriles was used to build an Ag-based network.

Synthesis and Characterization of Some Heterocyclic Compounds and Evaluation of Antibacterial Activity

In this study, heterocyclic compounds with two nitrogen atoms are prepared by reaction of 2-aminobenzimidazole with formic acid to get amide derivatives (A), reacts with phenylhydrazine to get phenyl hydrazone derivatives (B), reacts with ethyl chloroacetate to obtain ethyl acetate derivatives (C). The derivative (D) obtains on heating in a basic medium. The (B) reacts with 2-chloroacetyl chloride to give derivatives (E). A number of Schiff bases are prepared (F, I) from reacting 2-aminobenzimidazole with benzaldehyde derivatives. The(F) reacts with propargyl bromide to give propargyl bromide derivatives (G). The cyclization with 4-nitrophenyl azide leads to obtain triazole compound (H). The compound (I) reacts with ethyl chloroacetate to give ethyl acetate derivatives (J), reacts with hydrazine to give N-amide hydrazine derivatives (K). The cyclization give rises to 1,3,4-oxadiazole derivatives (L). The compound (I) reacts with sodium azide to obtain tetrazole derivatives (M). Synthesizing of Triazine, Oxadiazole, Triazole, Tetrazole via cyclization of the Schiff base derivatives with ethyl chloroacetate and chloro acetyl chloride, benzoic acid, 4-nitrophenyl azide, sodium azide and phenyl azide are possible respectively. The FT-IR, 13C-NMR and 1H-NMR spectral data give good evidence for the formation of the compounds. Some prepared compounds exhibit antibacterial properties.

Methods for Acrolein Detection: Recent Advances and Applications

Acrolein holds excellent potential as a critical biomarker in various oxidative stress-related diseases, and direct measurement of acrolein in biological systems is becoming essential to provide information for diagnosis and therapeutic purposes. In this review, we will discuss some available techniques for the detection of acrolein from biological samples. A conventional analytical method for the detection of acrolein by using high-performance liquid chromatography analysis after derivatization with 3-aminophenol is available. However, it is not suitable for high-throughput assay and inconvenient for measurement in clinical practice. On the other hand, we have recently discovered that phenyl azide can rapidly and selectively react with acrolein in a click manner to provide 4-formyl-1,2,3-triazoline through 1,3-dipolar cycloaddition. Moreover, we have successfully utilized this acrolein-azide click reaction as a simple and robust method for detecting and visualizing acrolein generated by live cells. Herein, we will describe our reaction-based acrolein sensor and its application to detect and visualize breast cancer tissues. We utilized the azide-acrolein click reaction-based method to discriminate breast cancer lesion from the normal breast gland, which resected from breast cancer patients. This method is the first example of an organic synthetic chemistry-based approach that can be used not only to visualize the cancer tissue but also to distinguish morphology of the resected tissue only within a few minutes. It has a potential clinical application for breast-conserving surgery. Furthermore, the ability to perform chemical reactions with cancer metabolites only at the desired cancer site is highly advantageous for cancer therapy.

Unravelling the strain-promoted [3+2] cycloaddition reactions of phenyl azide with cycloalkynes from the molecular electron density theory perspective

The increase of the strain not only increases the reaction rate and the exothermic character of these reactions, but also changes the mechanism for the small cycloalkynes from a non-polar to a polar reaction.

Site-Specific Protein Covalent Attachment to Nanotubes and Its Electronic Impact on Single Molecule Function

<p>Functional integration of proteins with carbon-based nanomaterials such as nanotubes holds great promise in emerging electronic and optoelectronic applications. Control over protein attachment poses a major challenge for consistent and useful device fabrication, especially when utilizing single/few molecule properties. Here, we exploit genetically encoded phenyl azide photochemistry to define the direct covalent attachment of three different proteins, including the fluorescent protein GFP, to carbon nanotube side walls. Single molecule fluorescence revealed that on attachment to SWCNTs GFP’s fluorescence changed in terms of intensity and improved resistance to photobleaching; essentially GFP is fluorescent for much longer on attachment. The site of attachment proved important in terms of electronic impact on GFP function, with the attachment site furthest from the functional center having the larger effect on fluorescence. Our approach provides a versatile and general method for generating intimate protein-CNT hybrid bioconjugates. It can be potentially applied easily to any protein of choice; attachment position and thus interface characteristics with the CNT can easily be changed by simply placing the phenyl azide chemistry at different residues by gene mutagenesis. Thus, our approach will allow consistent construction and modulate functional coupling through changing the protein attachment position.</p>

Site-Specific Protein Covalent Attachment to Nanotubes and Its Electronic Impact on Single Molecule Function

<p>Functional integration of proteins with carbon-based nanomaterials such as nanotubes holds great promise in emerging electronic and optoelectronic applications. Control over protein attachment poses a major challenge for consistent and useful device fabrication, especially when utilizing single/few molecule properties. Here, we exploit genetically encoded phenyl azide photochemistry to define the direct covalent attachment of three different proteins, including the fluorescent protein GFP, to carbon nanotube side walls. Single molecule fluorescence revealed that on attachment to SWCNTs GFP’s fluorescence changed in terms of intensity and improved resistance to photobleaching; essentially GFP is fluorescent for much longer on attachment. The site of attachment proved important in terms of electronic impact on GFP function, with the attachment site furthest from the functional center having the larger effect on fluorescence. Our approach provides a versatile and general method for generating intimate protein-CNT hybrid bioconjugates. It can be potentially applied easily to any protein of choice; attachment position and thus interface characteristics with the CNT can easily be changed by simply placing the phenyl azide chemistry at different residues by gene mutagenesis. Thus, our approach will allow consistent construction and modulate functional coupling through changing the protein attachment position.</p>