Differential Chromogenic Response towards F⁻ and H₂PO₄⁻: Hydrogen Bonding vs Deprotonation

Abstract

Highly colored oxidized 3,3 / -di(indolyl)arylmethanes (DIAM) based probes have been synthesized in good yield using modified single-step synthesis. The internal charge transfer state of the molecules as well as protonation equilibrium of indolyl units are dominated by the electronic nature of substituents (R = À CH 3 , À NMe 2 , À NO 2 etc) present on the central aryl moiety. However, irrespective to the nature of the substituents, all compounds (HL) show selective chromogenic response towards basic anions, like F À and H 2 PO 4 À etc in CH 3 CN. At low concentration, both analytes induce hypsochro-mic shifts in absorption maximum owing to the formation of Hbonded complex (HL …. A). However, only F À ion at high concentration results in a large bathochromic shift (~λ ∼ 90 nm) at λ max , probably due to the formation of deprotonated receptor (L À ), attributed by higher stability of H-bonded [HF 2 À ] dimer. Thus, one can easily discriminate between these ions via color-changing response. On the other hand, HSO 4À being an acidic anion results in protonation of indolyl nitrogen center (H 2 L + ) even at low concentration in CH 3 CN-H 2 O (1 : 1) mixture medium, leading to bathochromic shift of absorption maxima.

Fluorescent Nanoassembly of Tetrazole-Based Dyes with Amphoteric Surfactants: Investigation of Cyanide Sensing and Antitubercular Activity

“…The use of surfactant assemblies is expected to modify the physicochemical properties of the molecules. The extent of hydration at the surfactant-water interface will be less compared to bulk water, which can improve the possibility of different noncovalent interactions, like hydrogen bonding or charge pairing with target anions (Figure a). , Low apparent micropolarity inside the micellar/vesicular cavity along with high effective concentrations of the solubilized dyes ensures stronger intermolecular interaction. , Further, the compartmentalization effect of surfactant aggregates resists the self-association of polyaromatic dyes in water . This eventually improves the sensitivity of sensor molecules toward the targeting anions.…”

Copper(II) pseudoatrane appended heterobimetallic 2D‐MOF: A multi‐functional material with catalytic and sensing properties

“…This fact was also supported by the mass spectrum of this adduct which displayed a peak at 960.01 corresponding to [M + TBPA+K] + fragment (see Figure S48). Further, the plausible reason for a hypsochromic shift with PBP was the hydrogen bonding interactions between the phenolic hydrogen of flame retardant and the intense π‐networking architecture of 2D‐MOF 55–57 …”

“…Further, the plausible reason for a hypsochromic shift with PBP was the hydrogen bonding interactions between the phenolic hydrogen of flame retardant and the intense π-networking architecture of 2D-MOF. [55][56][57]…”

Multifaceted Applications of Luminescent Metalloporphyrin Derivatives: Fluorescence Turn-On Sensing of Nicotine and Antimicrobial Activity

“…On the contrary, optical sensing method offers distinct advantages: it is noninvasive and rapid and enables real-time monitoring without requiring complex sample preparation, making it suitable for on-site and continuous monitoring applications . Additionally, optical sensors can be miniaturized, allowing for the development of portable and cost-effective devices for nicotine detection. Moreover, optical sensing techniques tune sensitivity and selectivity when designed appropriately, making them promising for detecting trace amounts of nicotine in different types of samples, including biological fluids, environmental samples, and tobacco products. , …”