Synthesis, spectral characterization and photophysical studies of tetrahydroquinolines

Triflic acid-promoted Friedel-Crafts-type carbocyclization of alkenylated biphenyl derivatives: Synthesis and photophysical studies of novel 9,10-dihydrophenanthrenes

An efficient metal-free, triflic acid-promoted intramolecular Friedel-Crafts-type carbocyclization of alkenylated biphenyl derivatives is discussed. This method provides an elegant route for the construction of 9,10-dihydrophenanthrenes of biological significance in good to excellent yields. The carbocyclization reaction is likely to proceeds via activation of terminal C[bond, double bond]C bond of alkenylated biphenyl derivatives followed by subsequent aromatic electrophilic substitution to give desired carbocyclic products. Single crystal X-ray diffraction analysis of compound 10d revealed that the crystals are packed in AB-AB layer packing, where the molecules are aligned in anti-parallel fashion. Notably, all of the synthesized 9,10-dihydrophenanthrenes exhibited blue to greenish yellow fluorescence with λ max = 418-481 nm range. The stokes shift, quantum yield and optical band gap of tricyclic products were computed using their absorption and emission spectra. A significant positive solvatochromic effect was observed for 9,10-dihydrophenanthrene derivative 10l, which is a characteristic of ICT interactions.

Metal free synthesis of thermally stable blue fluorescent m-terphenyls by ring transformation of 2H-pyran-2-ones: chemical synthesis, spectroscopy and computational studies

A simple yet convenient nucleophile-induced synthetic route for the construction of thermally stable fluorescent active functionalized stilbenes has been delineated. The nucleophile-induced base encouraged synthetic protocol was performed under mild conditions without harming the environment and products were achieved in good yields. The synthesized stilbenes showed amazing emission properties and good thermal stability. Synthesized products displayed interesting positive solvatochromism in different solvents based on variation in polarity. Further, we present a comprehensive analysis of the eight molecules, leveraging a combination of Density Functional Tight Binding (DFTB), Density Functional Theory (DFT) calculations, and Molecular Dynamics (MD) simulations. This integrated approach allowed for an in-depth exploration of the electronic structures, reactivity profiles, and dynamic behaviors of these complex molecular systems. Our findings reveal significant insights into the physicochemical properties of the synthesized molecules, contributing to a deeper understanding of their potential applications in various fields.

Ultrasound-Assisted Metal-Free Synthesis of Functionalized 1,2-Teraryls by Ring Transformation Methodology

The function of styryl acetate as a carbanion nucleophile source has been explored in the ring transformation reaction of 2H-pyranones. The ultrasound assisted carbanion induced ring transformation of 4-amino-6-aryl-3-cyano-2H-pyran-2-ones using (E)-styryl acetate in the presence of KOH and DMF at room temperature is presented as an alternative strategy for the synthesis of functionalized 1,2-teraryls in high yields. This metal-free methodology provides easy access to a series of 1,2-teraryls and features broad functional group tolerance and mild reaction condition. Single crystal X-ray diffraction analysis of 4-(piperidin-1-yl)-6-(thiophen-2-yl)-[1,1'-biphenyl]-3-carbonitrile indicated that the crystal belongs to monoclinic system with a P21 space group having twisted aryl rings.