Synthesis of C3-Symmetric Triazine-Based Derivatives: Study of their AIEE, Mechanochromic Behaviors, and Detection of Picric Acid and Uric Acid in Aqueous Medium

Experimental and Theoretical Studies of Fluorescent "Turn Off" Sensor Functionalized With Carboxylic Acid and Naphthalene Group for Selective Detection of 2,4,6-Trinitrophenol

A fluorescent sensor, 5-((2-hydroxynaphthalen-1-yl)methyleneamino)benzene-1,3-dicarboxylic acid (coded as SB), containing both π-π interacting sites (such as π-electron-rich moieties) and hydrogen bonding (H-bonding) interacting sites (such as highly acidic protons) has been developed via high yield reflux method. It was characterized by the various analytical techniques such as Fourier transform-infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1 H-NMR), thermogravimetric analysis (TGA), field emission scanning electron microscope (Fe-SEM), elemental mapping, and UV - visible spectroscopy etc. The spectral response of the as-synthesized SB sensor has been investigated for various nitro explosives (NEs). It has been found that the SB sensor selectively and sensitive sense highly toxic 2,4,6-trinitrophenol (TNP) via the "turn-off" quenching response. Its limit of detection for TNP was calculated to be 30 ppb. Spectral overlap, detailed mechanistic studies for their mode of action, and density functional theory (DFT) calculations reveals that photo-induced electron transfer process (PET), fluorescence energy transfers process (FRET), and electrostatic interactions (i.e. H-bonding) are the key factors for the turn-off response of SB towards TNP. Notably, the synthesis of the sensor is cost-effective, energy efficient, and economic.

Functionalized Triazines and Tetrazines: Synthesis and Applications

The molecules possessing triazine and tetrazine moieties belong to a special class of heterocyclic compounds. Both triazines and tetrazines are building blocks and have provided a new dimension to the design of biologically important organic molecules. Several of their derivatives with fine-tuned electronic properties have been identified as multifunctional, adaptable, switchable, remarkably antifungal, anticancer, antiviral, antitumor, cardiotonic, anti-HIV, analgesic, anti-protozoal, etc. The objective of this review is to comprehensively describe the recent developments in synthesis, coordination properties, and various applications of triazine and tetrazine molecules. The rich literature demonstrates various synthetic routes for a variety of triazines and tetrazines through microwave-assisted, solid-phase, metal-based, [4+2] cycloaddition, and multicomponent one-pot reactions. Synthetic approaches contain linear, angular, and fused triazine and tetrazine heterocycles through a combinatorial method. Notably, the triazines and tetrazines undergo a variety of organic transformations, including electrophilic addition, coupling, nucleophilic displacement, and intramolecular cyclization. The mechanistic aspects of these heterocycles are discussed in a detailed way. The bioorthogonal application of these polyazines with various strained alkenes and alkynes provides a new prospect for investigations in chemical biology. This review systematically encapsulates the recent developments and challenges in the synthesis and possible potential applications of various triazine and tetrazine systems.