Visible light mediated synthesis of 1,3-diarylated imidazo[1,5-a]pyridines via oxidative amination of C-H catalyzed by graphitic carbon nitride.

Graphitic carbon nitride (g-C3N4) as a novel heterogeneous catalyst is employed for the visible light-mediated synthesis of the imidazo[1,5-a]pyridines via the oxidative amination of C-H bond at room temperature without the need for any additional solvent. Extensive characterization of the catalyst was performed using techniques such as FT-IR, PXRD, TGA, SEM and EDX analysis. The optimized conditions enabled the successful and expeditious conversion of a wide range of substrates to imidazo[1,5-a]pyridines in good yields; a notable advantage of this catalyst being recyclability, as it can be reused for up to five cycles without significant loss of activity. This feature makes it suitable for gram-scale synthesis of imidazo[1,5-a]pyridines. Additionally, this approach offers several benefits from a green chemistry perspective as affirmed by its favorable green chemistry metrics (GCM), including low process mass intensity (PMI), low E-factor, high atom economy (AE), and good reaction mass efficiency (RME) relative to existing protocols. In addition, chemical yield (CY), mass intensity (MI), mass productivity (MP) and optimum efficiency were also calculated. This environmentally friendly method offers multiple advantages and represents a significant advancement in the synthesis of imidazo[1,5-a]pyridines.

Calixarene Functionalized Supramolecular Liquid Crystals and Their Diverse Applications.

Liquid crystals are considered to be the fourth state of matter with an intermediate order and fluidity in comparison to solids and liquids. Calixarenes are among one of the most versatile families of building blocks for supramolecular chemistry due to their unique vaselike structure that can be chemically engineered to have different shapes and sizes. During the last few decades, calixarenes have drawn much attention in the field of supramolecular chemistry due to their diverse applications in the fields of ion and molecular recognition, ion-selective electrodes for catalysis, drug delivery, gelation, organic electronics and sensors, etc. Imbuing liquid crystallinity to the calixarene framework leads to functionalized calixarene derivatives with fluidity and order. Columnar self-assembly of such derivatives in particular enhance the charge migration along the column due to the 1D stacking due to the enhanced π-π overlap. Considering limited reports and reviews on this new class of calixarene based liquid crystals, a comprehensive account of the synthesis of calixarene liquid crystals along with their mesomorphic behavior and potential applications are presented in this review.