Oxidative Photocyclization of Aromatic Schiff Bases in Synthesis of Phenanthridines and Other Aza-PAHs

The oxidative photocyclization of aromatic Schiff bases was investigated as a potential method for synthesis of phenanthridine derivatives, biologically active compounds with medical applications. Although it is possible to prepare the desired phenanthridines using such an approach, the reaction has to be performed in the presence of acid and TEMPO to increase reaction rate and yield. The reaction kinetics was studied on a series of substituted imines covering the range from electron-withdrawing to electron-donating substituents. It was found that imines with electron-withdrawing substituents react one order of magnitude faster than imines bearing electron-donating groups. The 1H NMR monitoring of the reaction course showed that a significant part of the Z isomer in the reaction is transformed into E isomer which is more prone to photocyclization. The portion of the Z isomer transformed showed a linear correlation to the Hammett substituent constants. The reaction scope was expanded towards synthesis of larger aromatic systems, namely to the synthesis of strained aromatic systems, e.g., helicenes. In this respect, it was found that the scope of oxidative photocyclization of aromatic imines is limited to the formation of no more than five ortho-fused aromatic rings.

Stable carbamate pathway towards organic–inorganic hybrid perovskites and aromatic imines

A stable solid carbamate (MAC) composed of CH3NH3+ and CH3NHCO2− units exhibits high reactivity toward inorganic iodide and aromatic aldehyde.

UV–Vis Absorption Properties of New Aromatic Imines and Their Compositions with Poly({4,8-bis[(2-Ethylhexyl)oxy]Benzo[1,2-b:4,5-b′]Dithiophene-2,6-diyl}{3-Fluoro-2-[(2-Ethylhexyl)Carbonyl]Thieno[3,4-b]Thiophenediyl})

In this paper, four new aromatic imines containing at least one thiazole-based heterocycle were analyzed in detail by UV–Vis spectroscopy, taking into consideration their chemical structures and interactions with PTB7, a known polymeric electron donor widely used in bulk heterojunction organic solar cells. It is demonstrated that the absorption spectra of the investigated active compositions can be modified not only by changing the chemical structure of imine, but also via formulations with PTB7. For all investigated imines and PTB7:imine compositions, calibration curves were obtained in order to find the optimum concentration in the composition with PTB7 for expansion and optimization of absorption spectra. All imines and PTB7:imine compositions were investigated in 1,2-dichlorobenzene by UV–Vis spectroscopy in various concentrations, monitoring the changes in the π–π* and n–π* transitions. With increasing imine concentrations, we did not observe changes in absorption maxima, while with increasing imine concentrations, a hypochromic effect was observed. Finally, we could conclude that all investigated compositions exhibited wide absorptions of up to 800 nm and isosbestic points in the range of 440–540 nm, confirming changes in the macromolecular organization of the tested compounds. The theoretical calculations of their vibration spectra (FTIR) and LUMO–HOMO levels by Density Functional Theory (DFT) methods are also provided. Finally, IR thermal images were measured for organic devices based on imines and the imine:PTB7 composite.

Synthesis, Characterization and Evaluation of Antimicrobial Properties of (R)-(-)-4-Phenyl-2 Oxazolidinone Based Azetidinones

Introduction: A series of (R)-(-)-4-Phenyl-2 oxazolidinone based azetidinones (4a-i) were synthesized from the reaction of (2-Oxo-4-phenyl-oxazolidin-3-yl) acetic acid with aromatic imines (3a-i) in the presence of Thionyl chloride and Triethylamine as a base. Methods: The transformation proceeds through the formation of acid chloride to ketene which finally forms the azetidinones through [2+2] cycloaddition with aromatic imines. Products obtained were screened to evaluate their antibacterial activity with respect to known bacteria like Escherichia Coli (E. Coli) and Bacillus subtilis. Results and Conclusion: In most of the cases, azetidinones were found to exhibit superior antimicrobial properties than oxazolidinones. They were found to be a good inhibitor of gram-positive and gramnegative bacteria. Enhancement of antibacterial property can be attributed to the presence of azetidinone ring and hydrophobic alkyl side chain in the scaffolds.

Mechanistic study of the ligand controlled regioselectivity in iridium catalyzed C–H borylation of aromatic imines

DFT calculation indicates that in iridium catalyzed C–H borylation of aromatics, the ortho selectivity is proposed to be attributed to the electron donating effect of AQ ligand, while the meta selectivity is due to steric hindrance of TMP ligand.