First binuclear complex of an N,N′,N″,N‴-tetraalkyl 2,5-diamino-1,4-benzoquinonediimine

Siri, Olivier; Braunstein, Pierre

doi:10.1039/b005952h

Cited by 45 publications

(43 citation statements)

References 17 publications

(16 reference statements)

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“…[9,10] Tetraaminobenzene was first reacted with benzoyl chloride in acetonitrile and NEt 3 , to afford the tetrabenzamidobenzene (4) , which facilitates purification by crystallisation of its protonated forms. The acido±basic properties were thus examined in a mixture methanol/water (80/20 w/w).…”

Section: Resultsmentioning

confidence: 99%

“…These 12p electron molecules should actually be better considered as constituted of two 6p subsystems, [8] chemically connected by CÀC single bonds but electronically not conjugated (Scheme 1). [9,10] We have previously shown that N-neopentyl p-benzoquinonediimine [9] L 1 undergoes significant spectrophotometric changes as a function of pH. [10] Upon successive protonation of L 1 , ™mono∫ and ™double∫ cyanine-type chromophores are generated in solution.…”

Section: Introductionmentioning

confidence: 99%

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Acid–Base Sensors Based on Novel Quinone‐Type Dyes

Elhabiri

Siri

Sornosa-Tent

et al. 2003

Chemistry A European J

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We present a detailed study on the acid-base behaviour of a family of "potentially antiaromatic" p-benzoquinonediimine ligands. These 12pi electron molecules can be considered as constituted of two chemically connected but electronically not conjugated 6pi-electron subunits. Upon successive protonation, "mono" and "double" cyanine-type chromophores are generated in solution and allow a precise and sensitive spectrophotometric detection. These molecules represent a new class of tunable quinones whose electronic and structural properties can be triggered by proton input, as established by a complete physico-chemical study involving a combination of potentiometric and spectrophotometric methods (absorption and emission).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Acid–Base Sensors Based on Novel Quinone‐Type Dyes

Elhabiri

Siri

Sornosa-Tent

et al. 2003

Chemistry A European J

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“…Although 9 led also to the formation of a head-to-tail hydrogen-bonded network, it revealed an unexpected wave-like arrangement owing to the presence of two N-neopentyl substituents (Figure 3a). [15] With four N-neopentyl substituents, the 2,5-diamino-1,4-benzoquinonediimine 15 [20] led instead to a different packing arrangement owing to the steric hindrance induced by the presence of these four substituents (Figure 3b). [21] In this case, the stacking results from intermolecular p±p interactions.…”

Section: Resultsmentioning

confidence: 96%

Toward a 6π+6π Zwitterion or a Bioinhibitors‐Related OH‐Substituted Aminoquinone: Identification of a Key Intermediate in Their pH Controlled Synthesis

Braunstein

Siri

Taquet

et al. 2004

Chemistry A European J

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Their pH-controlled reactivity places the N,N'-dialkyl-2-amino-5-lithium alcoholate-1,4-benzoquinonemonoimines [C(6)H(2)(NHCH(2)R') (=NCH(2)R')(=O)(OLi)] 7 (R'=tBu) and 8 (R'=p-C(6)H(4)-tBu) at the crossroads of a new versatile strategy for the preparation of two very different classes of substituted quinones. We describe new 2-(N-alkyl)amino-5-hydroxy-1,4-benzoquinones, which are parent molecules to biologically active substituted aminobenzoquinones, for which changes of the N-substituent will become readily possible. The results of the first X-ray structural determination of such compounds ([C(6)H(2)(NHCH(2)tBu)(OH)(=O)(2)] 13) are also reported and we compare the influence of the number of N-substituents of the C(6) ring on the supramolecular networks resulting from self-assembling of 13, zwitterionic N,N'-dineopentyl-2-amino-5-alcoholate-1,4-benzoquinonemonoiminium [C(6)H(2)(=NHCH(2)tBu)(2)(=O)(2)] 9 and N,N',N",N"'-tetraneopentyl-2,5-diamino-1,4-benzoquinone diimine [C(6)H(2)(NHCH(2)tBu)(2)(=NCH(2)tBu)(2)] 15.

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“…Figure 2) and compared with the spatial magnetic properties of the iso-electronic para-benzoquinone 2. The former compound is expected to be potentially antiaromatic 46 and, due to the special substitution, is estimated from the X-ray structure to consist of two independent 6π-electron trimethine cyanine subunits 47 which are connected via two C-C single bonds (ca. 1.5 Å in length both from X-ray measurements as well as by DFT calculations).…”

Section: Methodsmentioning

confidence: 99%

Spatial magnetic properties subject to lone pair and π electron delocalization in benzenoid and quinoid structures. Are quinoid tautomers really nonaromatic?

Kleinpeter

Koch²

2011

Arkivoc

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The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of benzenoid and quinoid tautomeric structures such as benzodifurantrione and phenazine-type molecules have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept of Paul von Ragué Schleyer and visualized as iso-chemicalshielding surfaces (ICSS) of various size and direction. The TSNMRS values were employed to quantify and visualize the partial aromaticity of the studied compounds. In the case of the surprisingly more stable quinoid tautomers, the aromaticity-synonymous with stability due to the conjugation of π electrons and lone pairs-was not found to be particularly reduced.

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First binuclear complex of an N,N′,N″,N‴-tetraalkyl 2,5-diamino-1,4-benzoquinonediimine

Cited by 45 publications

References 17 publications

Acid–Base Sensors Based on Novel Quinone‐Type Dyes

Acid–Base Sensors Based on Novel Quinone‐Type Dyes

Toward a 6π+6π Zwitterion or a Bioinhibitors‐Related OH‐Substituted Aminoquinone: Identification of a Key Intermediate in Their pH Controlled Synthesis

Spatial magnetic properties subject to lone pair and π electron delocalization in benzenoid and quinoid structures. Are quinoid tautomers really nonaromatic?

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