Pseudo-oxocarbons. Synthesis of 2,1,3-bis-, and 1,2,3-tris (dicyanomethylene) croconate salts. New bond-delocalized dianions, croconate violet and croconate blue

Fatiadi, Alexander J.

doi:10.6028/jres.085.005

Cited by 7 publications

(2 citation statements)

References 18 publications

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“…Oxocarbons are an important class of anionic molecules formed by “ n ” carbon and oxygen atoms with general formula (C n O n ) 2– , where “ n ” varies from 3 to 6 for deltate, squarate, croconate, and rhodizonate, respectively. , Such systems possess interesting structural features such as flat cyclic structures, high molecular symmetry ( D nh ) and an extensive π electron delocalization. − The partial or total substitution of the oxygen atoms by other groups originates systems named pseudo-oxocarbons, , and the oxygen(s) substitution(s) in the squaric acid (H 2 Sq, n = 4) by nitrogenous groups engenders the so-called squaraines, , see Figure a.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 Such systems possess interesting structural features such as flat cyclic structures, high molecular symmetry (D nh ) and an extensive π electron delocalization. 2−4 The partial or total substitution of the oxygen atoms by other groups originates systems named pseudo-oxocarbons, 5,6 and the oxygen(s) substitution(s) in the squaric acid (H 2 Sq, n = 4) by nitrogenous groups engenders the so-called squaraines, 5,7 see Figure 1a.…”

Section: ■ Introductionmentioning

confidence: 99%

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

et al. 2014

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The crystal structures, synthesis procedure, thermal behavior, and spectroscopic properties of a new squaraine SqINH·H2O and its anhydrous arrangement are described. This squaraine is obtained through an acid-base reaction using squaric acid (H2Sq) and isoniazid (INH) as precursors. Both squaraines crystallize in the monoclinic system, but in different space groups: the hydrated and anhydrous arrangement crystallizes in the P2₁ and P2₁/c space group, respectively. The crystallographic data strongly suggest that the structures present an expressive increase in their electronic delocalization all over the molecular structure of both compounds, when compared with the reagents. The bond distances for both structures present an average value intermediate between a single and double character (1.463(3) Å for SqINH·H2O and 1.4959(3) Å for SqINH). The vibrational and electronic data also corroborate with this proposal, since the band shifts indicate that the conjugation over the system is increased, as indicated by the blue shift observed for the carbonyl stretching bands for both compounds. The presence of the water molecule is responsible for a decrease in fluorescence emission, as determined by the emission spectra recorded for both compounds.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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

et al. 2014

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Croconaine Dyes – the Lesser Known Siblings of Squaraines

Lynch

Hamilton

2017

Eur J Org Chem

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In the 50+ years since the first squaraine dye, made by using 3,4‐dihydroxycyclobut‐3‐ene‐1,2‐dione (squaric acid), was reported, numerous analogues have not only been made and published, but similarly, a number of good review articles on squaraine dyes has also been published. In contrast, for the majority of this time, reports of croconaine dyes, made by using 4,5‐dihydroxy‐4‐cyclopentene‐1,2,3‐trione (croconic acid), have also been published, but they have not received the same attention as squaraine dyes. Furthermore, the only known review of croconaine dyes, which was recently published, is written in Chinese. This current review aims to document the history of croconaine dyes since their first report in a German patent in 1970. This review sources both the scientific literature and published patents, and attention is given to both synthesis and spectroscopic details.

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Laser desorption mass spectrometry of squaric acid and its salts

Byrd

Fatiadi

Simons

et al. 1986

Org. Mass Spectrom.

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The laser desorption mass spectrometry of the oxocarbon squaric acid (3,4-dihydroxy-3-cyclobutene-1,2dione) and its salts of the form A&O, (A = cation) is described. Both positive and negative ion spectra were obtained. The positive ion spectrum of the acid is characterized by an ion corresponding to loss of CO from [M + HI'. The negative ion spectrum shows an intense [M -HI-peak in addition to a dimer species. The alkali salt spectra contain [M + A]+ in the positive mode and [M -A]-and an intense [C,HO,]-in the negative mode. The smaller alkali salts also have an [M + HI+ adduct ion. Unlike the alkali squarates, the ammonium salt shows ions corresponding to losses of neutrals from the molecular adduct in the positive ion spectrum and a dimer species in the negative ion spectrum. Molecular weight information was obtained in all cases. A (bis)dicyanomethylene derivative of potassium sqnarate was also studied. Some field desorption mass spectrometry results are presented for comparison.

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Pseudo-oxocarbons. Synthesis of 2,1,3-bis-, and 1,2,3-tris (dicyanomethylene) croconate salts. New bond-delocalized dianions, croconate violet and croconate blue

Cited by 7 publications

References 18 publications

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

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

Croconaine Dyes – the Lesser Known Siblings of Squaraines

Laser desorption mass spectrometry of squaric acid and its salts

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