Squaraines: Crystal Structures and Spectroscopic Analysis of Hydrated and Anhydrous Forms of Squaric Acid-Isoniazid Species

Reis, Felipe Dias dos; Gatti, Isabela Marangon Christo; Garcia, Humberto C.; Oliveira, Vanessa E. de; Oliveira, Luiz Fernando Cappa de

doi:10.1021/jp509502w

Cited by 4 publications

(2 citation statements)

References 40 publications

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“…The corresponding C−N distances in betaines of squaric acid in which the formal positive charge resides elsewhere in the molecule instead of the nitrogen atom bonded to the four-membered ring are significantly shorter than the C1−N1 bond length in 1 by ca. 0.12 Å, reflecting the squaramide nature of these structures [20][21][22][23]. The C4−C1−C2 bond angle in 1 is comparable to the average of the corresponding bond angle of 96.2° of the aforementioned previously reported betaines [11][12][13][14][15][16][17]19].…”

Section: Structural Description Of 1 In the Solid-statesupporting

confidence: 72%

Structural Elucidation of the Triethylammonium Betaine of Squaric Acid

Palme,

Goddard,

Leutzsch

et al. 2023

Molbank

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Betaines of squaric acid have gained research interest because of their structural and spectral properties. We elucidated the crystal and molecular structure of the triethylammonium betaine of squaric acid (1) by X-ray crystallography, IR, and NMR spectroscopy augmented by Hirshfeld surface analysis and DFT calculations. The crystal structure determination using Hirshfeld atom refinement reveals that the resonance hybrid structure with partial enolate character of the two lateral squaric acid C=O groups describes 1 best. The solid-state supramolecular structure features weak intermolecular C−H···O hydrogen bonds. The number of C=O bands in the IR spectrum in the solid-state is consistent with local C2v symmetry of the squaric acid residue in 1. The 13C NMR signals of this group in solution were assigned based on 2D NMR experiments and computational prediction using the Gauge-Independent Atom Orbital (GIAO) method. The present study provides the first structural characterization of a betaine of squaric acid containing a four-coordinate nitrogen atom directly attached to the four-membered ring.

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Section: Structural Description Of 1 In the Solid-statesupporting

confidence: 72%

Structural Elucidation of the Triethylammonium Betaine of Squaric Acid

Palme,

Goddard,

Leutzsch

et al. 2023

Molbank

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“…A squaric acid molecule contains two ketonic oxygen atoms and two hydroxyl groups. It is easy to form hydrogen bond with other molecules containing donor or acceptor atoms [10][11][12] . 2,6-Bis(2benzimidazolyl)pyridine molecule contains two secondary amine and two tertiary amine, which could act as donor and acceptor in the formation of hydrogen bond.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Evidence for Supramolecular Self-Assembly and Hydrogen Bonding between Squaric Acid and 2, 6-Bis(2-benzimidazolyl)pyridine

HU¹,

PAN²,

CHENG³

et al. 2016

Acta Physico-Chimica Sinica

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Supramolecular complex (1) was obtained from a mixture of squaric acid and 2,6-bis(2benzimidazolyl)pyridine in deuterated dimethylsulfoxide (d-DMSO) and characterized by single-crystal X-ray diffraction. The crystal structure data showed that 1 was a one-dimensional chain polymer assembled through π-π stacking and hydrogen bonding interactions. Infrared vibrational spectra of 1 were measured at different temperatures and sample concentrations in carbon tetrachloride. Moreover, the hydrogen bonding in the crystals was further evaluated by density functional theory (DFT) and atoms in molecules (AIM) theory. The calculated hydrogen bonding energies were about 135.65 and 49.40 J•mol-1 , respectively.

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Surface‐enhanced Raman scattering of Cis‐(dicyanomethylene) squarate ion on a silver substrate

Marques,

Milán‐Garcés,

de Oliveira

et al. 2024

J Raman Spectroscopy

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There has been increasing interest in the use of squaraines with different physicochemical properties. However, their applications in nanoplasmonics are limited. For that, detailed information on the interactions of squaraines with plasmonic nanostructures is required. In this work, we have studied the adsorption of the squaraine cis‐dicyanomethylene squarate (CDSQ) on the surface of Ag nanoparticles (AgNP). We have combined normal Raman, surface‐enhanced Raman scattering (SERS), and DFT calculations to get insights into the configuration of its adsorption. DFT calculations have been carried out using simplified models of different adsorption geometries for comparison with the results of the SERS experiments. A comparison between the relative intensities of the normal Raman and SERS spectra indicates that CDSQ is adsorbed perpendicular to the AgNP surface. The predicted spectra suggest that CDSQ is chemically adsorbed on the silver surface through one of its N atoms.

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Squaraines: Crystal Structures and Spectroscopic Analysis of Hydrated and Anhydrous Forms of Squaric Acid-Isoniazid Species

Cited by 4 publications

References 40 publications

Structural Elucidation of the Triethylammonium Betaine of Squaric Acid

Structural Elucidation of the Triethylammonium Betaine of Squaric Acid

Experimental and Theoretical Evidence for Supramolecular Self-Assembly and Hydrogen Bonding between Squaric Acid and 2, 6-Bis(2-benzimidazolyl)pyridine

Surface‐enhanced Raman scattering of Cis‐(dicyanomethylene) squarate ion on a silver substrate

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