The first examples of supramolecular discotic C3h tris(N-salicylideneamine)s featuring inter- and intra-molecular H-bonding: synthesis and characterization

Yelamaggad, C. V.; Prabhu, Rashmi; Rao, D. S. Shankar; Prasad, S. Krishna

doi:10.1016/j.tetlet.2010.06.124

Cited by 31 publications

(11 citation statements)

References 36 publications

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“…al . reported liquid crystalline hydrazone derivatives back in 1993, which was later followed by various LC hydrazone derivatives exhibiting lamellar phases, metallomesogens exhibiting crossover phenomenon and stabilization of room temperature columnar phase due to the supramolecular hexatic arrangements etc …”

Section: Introductionmentioning

confidence: 99%

Substituted Aroylhydrazone Based Polycatenars: Tuning of Liquid Crystalline Self‐Assembly

et al. 2018

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A systematic investigation on mesomorphic properties of two new classes of substituted-aroylhydrazones having semi-flexible ester (ester based polycatenars) and flexible ether linker (ether based polycatenars) with variable alkoxy chain length (n = 6, 8, 10, 12, 14, 16) are described. The members of each series with six soft alkoxy chains formed columnar self-assembly as confirmed by differential scanning calorimetry analysis, polarized optical microscopy and powder X-ray diffraction studies. For the ester based polycatenar scaffolds, the mesophase of lower alkoxy chain members exhibited columnar oblique phase which further transformed to columnar hexagonal phase with the increase in the chain length and thus showing a mesophase crossover phenomenon. In the case of ether based polycatenars, the presence of ether link provides significant stabilization of the columnar oblique phase for all the members except the lower homologues. The driving forces for the appearance of columnar self-assembly are the intermolecular hydrogen-bonding interactions between the amide groups (-C=O···H-N-) of aroylhydrazone core, which was confirmed by the temperature dependent IR studies. In addition, both the series of compounds exhibit good gelation properties, which is assisted by the intermolecular hydrogen bonding.[a] Dr.

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Section: Introductionmentioning

confidence: 99%

Substituted Aroylhydrazone Based Polycatenars: Tuning of Liquid Crystalline Self‐Assembly

et al. 2018

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“…Thee nol-iminef orm is generallyt he mosts table at room temperature, [30,31] even if it is in rapid equilibrium with the keto-enamine form. [37,38] The equilibrium between the enol-imine and the keto-enamine forms, togetherw ith the resonance contribution of az witterionic intermediate, explains the unusual stability of this imine, and the locked conformation (trans for the imine, cis for the enamine)o ft his motif. [37,38] The equilibrium between the enol-imine and the keto-enamine forms, togetherw ith the resonance contribution of az witterionic intermediate, explains the unusual stability of this imine, and the locked conformation (trans for the imine, cis for the enamine)o ft his motif.…”

Section: Introductionmentioning

confidence: 99%

“…Only in af ew cases has the keto-enamine form been reported as the majori somer in salicylaldimines, [32][33][34][35][36] but it is known to be more stable in other polyaromatic o-hydroxyimine compounds. [37,38] The equilibrium between the enol-imine and the keto-enamine forms, togetherw ith the resonance contribution of az witterionic intermediate, explains the unusual stability of this imine, and the locked conformation (trans for the imine, cis for the enamine)o ft his motif. This fixed geometry has been used to selectively synthesize some Schiff-base macrocycles.…”

Section: Introductionmentioning

confidence: 99%

“…The enol‐imine form is generally the most stable at room temperature, even if it is in rapid equilibrium with the keto‐enamine form. Only in a few cases has the keto‐enamine form been reported as the major isomer in salicylaldimines, but it is known to be more stable in other polyaromatic o ‐hydroxyimine compounds . The equilibrium between the enol‐imine and the keto‐enamine forms, together with the resonance contribution of a zwitterionic intermediate, explains the unusual stability of this imine, and the locked conformation ( trans for the imine, cis for the enamine) of this motif.…”

Section: Introductionmentioning

confidence: 99%

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The Rich Tautomeric Behavior of Campestarenes

Chen

Guieu

White

et al. 2016

Chemistry A European J

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Campestarenes are a new family of Schiff-base macrocycles that form selectively in a one-step synthesis. These macrocycles with five-fold symmetry show solvent-dependent tautomerization and dimerization or aggregation. In this paper, we have prepared new soluble campestarenes that do not aggregate. The initial single-crystal X-ray diffraction study of a campestarene reveals that these macrocycles are nearly flat. The tautomeric behavior of the campestarenes has been extensively studied by variable-temperature, multinuclear NMR spectroscopy, UV/Vis spectroscopy, and IR spectroscopy. In polar solvents, such as DMF, the molecules exist predominantly in their keto-enamine form, but the enol-imine tautomer is dominant in non-polar solvents. A detailed computational study of the tautomeric forms of campestarenes provides a theoretical basis for their behavior and corroborates the experimental data. The results of this study give the first comprehensive understanding of the electronic and spectroscopic properties of these pentagonal macrocycles.

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“…This approach makes it possible to enhance a fluorescent quantum yield of these compounds which refer to the mechanically coupled biconcave systems [ 11 ]. Tris -salicylideneanilines with long liquid crystal substituents have been recently classified as a new class of discotic liquid crystal substances [ 12 , 13 ], where a triple quasi-aromatic core is the basic fragment. The physicochemical characteristics of the aforesaid compounds enable the employment in organic electronics, optoelectronics and photovoltaics, as a molecular logic gate, photochromic crystals and reversible molecular switches [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Triple hydrogen bonding in a circular arrangement: ab initio, DFT and first-principles MD studies of tris-hydroxyaryl enamines

Martyniak

Panek

Jezierska

et al. 2012

J Comput Aided Mol Des

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First-principles Car-Parrinello molecular dynamics, ab initio (MP2) and density functional schemes have been used to explore the tautomeric equilibrium in three tris(amino(R)methylidene)cyclohexane-1,3,5-triones (R = hydrogen, methyl or phenyl group). The dynamic nature of the cyclic hydrogen bonding has been studied by the first-principles MD method. The comparison of the results obtained by aforesaid methods has been accomplished on the basis of calculations of structural and spectroscopic characteristics of the compounds. The conformational analysis of the studied compounds has been carried out at the MP2/6-31+G(d,p) and B3LYP/6-31+G(d,p) levels of theory. The influence of steric and electronic effects on the cyclic hydrogen bonding has been analysed. The extent of the proton delocalization has been modified by the substituents according to the sequence: hydrogen < phenyl < methyl. This fact is verified by the spectroscopic and structural data as well as the energy potential curve. A prevalence of the keto-enamine tautomeric form has been observed in the static ab initio and DFT models, and confirmed by the first-principles MD.Electronic supplementary materialThe online version of this article (doi:10.1007/s10822-012-9597-3) contains supplementary material, which is available to authorized users.

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The first examples of supramolecular discotic C3h tris(N-salicylideneamine)s featuring inter- and intra-molecular H-bonding: synthesis and characterization

Cited by 31 publications

References 36 publications

Substituted Aroylhydrazone Based Polycatenars: Tuning of Liquid Crystalline Self‐Assembly

Substituted Aroylhydrazone Based Polycatenars: Tuning of Liquid Crystalline Self‐Assembly

The Rich Tautomeric Behavior of Campestarenes

Triple hydrogen bonding in a circular arrangement: ab initio, DFT and first-principles MD studies of tris-hydroxyaryl enamines

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