Conformational tuning of molecular network stabilized via C-H….π &amp; π-π interaction in 2-[2-(3-cyano-4, 6-dimethyl-2-oxo-2H-pyridin-1-yl-methyl)-benzyloxy]-4, 6-dimethyl-nicotinonitrile

Tewari, Ashish Kumar; Dubey, Rajeev K.

doi:10.3998/ark.5550190.0010.a25

Cited by 7 publications

(2 citation statements)

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“…A greater insight into the fluorescence of solution and solids is presented in the Section . The importance of CH−π interactions associated with biomolecules, conformational selectivity, and molecular recognition − has been described in the literature. To our surprise, when [ 1 ] and [ 2 ] were prepared as KBr pellets for infrared spectra characterization, unexpected color change was identified by the naked eye within ∼1 min of mechanical grinding, due to a significant number of weak to moderate interactions identified in both [ 1 ] and [ 2 ].…”

Section: Resultsmentioning

confidence: 99%

Distinct Tetracyanoquinodimethane Derivatives: Enhanced Fluorescence in Solutions and Unprecedented Cation Recognition in the Solid State

et al. 2021

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Tetracyanoquinodimethane (TCNQ) is known to react with various amines to generate substituted TCNQ derivatives with remarkable optical and nonlinear optical characteristics. The choice of amine plays a crucial role in the outcome of molecular material attributes. Especially, mono/di-substituted TCNQ’s possessing strong fluorescence in solutions than solids are deficient. Furthermore, cation recognition in the solid-state TCNQ derivatives is yet undetermined. In this article, we present solution-enhanced fluorescence and exclusive solid-state recognition of K+ ion achieved through the selection of 4-(4-aminophenyl)morpholin-3-one (APM) having considerable π-conjugation and carbonyl (CO) functionality, particularly in the ring. TCNQ when reacted with APM, in a single-step reaction, resulted in two well-defined distinct compounds, namely, 7,7-bis(4-(4-aminophenyl)morpholin-3-ono)dicyanoquinodimethane (BAPMDQ [1], yellow) and 7,7,8-(4-(4-aminophenyl)morpholin-3-ono)tricyanoquinodimethane (APMTQ [2], red), with increased fluorescence intensity in solutions than their solids. Crystal structure investigation revealed extensive C–H−π interactions and strong H-bonding in [1], whereas moderate to weak interactions in [2]. Surprisingly, simple mechanical grinding during KBr pellet preparation with [1, 2] triggered unidentified cation recognition with a profound color change (in ∼1 min) detected by the naked eye, accompanied by a drastic enhancement of fluorescence, proposed due to the presence of carbonyl functionality, noncovalent intermolecular interactions, and molecular assemblies in [1, 2] solids. Cation recognition was also noted with various other salts as well (KCl, KI, KSCN, NH4Cl, NH4Br, etc.). Currently, the recognition mechanism of K+ ion in [1, 2] is demonstrated by the strong electrostatic interaction of K+ ion with CO and simultaneously cation−π interaction of K+ with the phenyl ring of APM, supported by experimental and computational studies. Computational analysis also revealed that a strong cation−π interaction occurred between the K+ ion and the phenyl ring (APM) in [2] than in [1] (ΔG binding calculated as ∼16.3 and ∼25.2 kcal mol–1 for [1] and [2], respectively) providing additional binding free energy. Thus, both electrostatic and cation−π interactions lead to the recognition. Scanning electron microscopy of drop-cast films showed microcrystalline “roses” in [1] and micro/nano “aggregates” in [2]. Optical band gap (∼3.565 eV) indicated [1, 2] as wide-band-gap materials. The current study demonstrates fascinating novel products obtained by single-pot reaction, resulting in contrasting optical properties in solutions and experiencing cation recognition capability exclusively in the solid state.

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Section: Resultsmentioning

confidence: 99%

Distinct Tetracyanoquinodimethane Derivatives: Enhanced Fluorescence in Solutions and Unprecedented Cation Recognition in the Solid State

et al. 2021

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“…8 The crystal structure of various organic compounds usually shows C-HÁ Á ÁO weak interactions. [9][10][11][12][13][14] These bonds also play an important role in native and misfolded proteins. 15 Recently, 1-(2-naphthyl)-3-methyl-5-pyrazolone coupled with capillary electrophoresis with diode array detection for the determination of carbohydrates such as mannose, galacturonic acid, glucuronic acid, rhamnose, glucose, galactose, xylose, arabinose and fucose has been developed.…”

Section: Introductionmentioning

confidence: 99%