Thermochromism and photochromism of aryl substituted acyclic azines: Uncatalised and acid-catalised thermal isomerisation

doi:10.1016/S0040-4020(01)92431-7

Tetrahedron

Volume 37, Issue 3, 1981, Pages 569-573

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Abstract

The photochemical E-Z isomerisation of the benzophenone-9-anthraldehyde azine (1), benzophenone-9-acridine aldehyde azine (2) and 9-anthraldehyde azine (3) is thermally reversible. The thermal reaction gives the same isomers as the photochemical reaction. We have studied the mechanism of the thermal isomerisation of these azines. Our results are in accordance with an inversion of the N atom which is connected with a rotation movement about the N-N single or the CN double bond.

References (34)

K. Appenroth et al.
J. Photochem.
(1980)
K. Appenroth et al.
J. Photochem.
(1980)
J.F. Ogilvie et al.
Spectrochim. Acta
(1971)
H. Mauser
(1974)
D. Wurmb-Gerlich et al.
Liebigs Ann.
(1967)
J.M. Lehn
Fortschr. chem. Forschg.
(1970)
J. Bjørgo et al.
J. Chem. Soc. Perkin 1
(1977)
D. Kolbah et al.
4. Communication; 3. Communication, see Ref....
R. Paetzold et al.
Z. Chem.
(1974)

J. Elguero et al.

Bull. Soc. Chim. Fr.

(1969)

D.S. Malament et al.

J. Am. Chem. Soc.

(1970)

J. Elguero et al.

Bull. Soc. Chim. Fr.

(1968)

H. Kessler

Angew. Chem.

(1970)

H. Kessler

Tetrahedron

(1974)

K. Appenroth, M. Reichenbächer and R. Paetzold, in preparation; see also K. Gustav and S. Vettermann, Wiss. Z. FSU Jena...

W.B. Jennings et al.

J. Chem. Soc. Perkin 2

(1975)

W.B. Jennings et al.

J. Am. Chem. Soc.

(1972)

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Azines: Synthesis, structure, electronic structure and their applications
2019, Organic and Biomolecular Chemistry
Azines are organic molecules which bear the C-N–N-C functional unit. In the recent past, azines have received increased attention due to the recognition of their biological, chemical and materials properties. Azines have been conventionally synthesised by the condensation of hydrazine with ketones and aldehydes, and many alternate routes are also available. Azines have been extensively studied to investigate the presence or absence of conjugation with the help of computational studies and crystal structure analysis owing to their importance in nonlinear optics. The tautomerism in azines is a topic of contemporary interest. Herein, we present a review of recent advances in the structure and electronic structure properties of azines along with information on the modern methods of their synthesis and application as precursors in generating heterocycles in organic synthesis and in medicinal chemistry. A few applications of azines in the field of materials chemistry in developing metal–organic frameworks (MOFs), covalent organic frameworks (COFs), energetic materials and chemosensors are also included.
From lithium ketazides to isomeric silylketazine-rings - imine-enamine tautomerism
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Di(tert-butylmethyl)ketazine (I) reacts with n-BuLi in a 1:1 molar ratio to give a monolithium salt (II). The reaction of II with ^tBu₂SiF₂ in n-hexane leads, even in a 1:1 molar ratio, to the formation of the isomeric five- and four-membered ring compounds 1 and 2. Compound 1 has an endocyclic imine and an exocyclic enamine unit. The opposite is found for 2. The acyclic monosubstitution product, ^tBu₂SiFCH₂–C^tBuN–NC^tBuCH₃ (III) could not be isolated. It reacts with the lithium ketazide to give 1 or 2. I is reformed. The reaction in THF yields only the four-membered ring 2. In a comparable reaction of the lithium ketazide and (H₃C)₂SiF₂, the substitution product 3 could be isolated. A possible formation mechanism for 2 includes an intermediate silene IV. Both compounds 1 and 2 react with H₃C–OH under cleavage of the endocyclic Si–N-bond to give the addition product 5. The reaction mechanism includes a hydrogen shift from a nitrogen atom to a carbon atom via an imine-enamine tautomerism. In a 2:1 molar ratio, n-BuLi and the di(tert-butylmethyl)-ketazine (I) form the dilithium salt, 6. Compound 6 crystallizes from THF as trimer with four imine and two enamine units. A seven-membered ring (7) isomeric to 1 and 2 is the result of the reaction of 6 with ^tBu₂SiF₂. Compound 7 contains one imine and one enamine unit in the ring skeleton.
The comparable reaction of the (CH₃)₃Si-substituted dilithium-di(tert-butylmethyl)ketazide and ^tBu₂SiF₂ yields the five-membered ring compound 8 with one endocyclic imine and one exocyclic enamine unit.
Quantum chemical calculations of 1, 2, 7 and the intermediate silene IV have been carried out and show a low energy difference between the cyclic silyl-ketazine isomers.
Temperature dependence of the phase transitions of benzaldazine and its o-, m-, and p-nitro derivatives
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The dielectric constants of benzaldazine (BA) and its nitro derivatives have been measured at different frequencies up to 200 kHz. The measurements were carried out at temperatures up to and near the melting point of each sample. Two phase transitions were obtained during measurements at 310 and 480 K. Inversion NN rotation and inversion CN rotation mechanisms may be responsible for these transitions. The effect of interaction between the strongly polar NO₂ group of o-, m- or p-nitrobenzaldazine and the central aldimino (CHN) groups on the dielectric constant is discussed. The electric dipole moments of the samples were calculated at the peak positions, and are discussed.
Electrical and spectral studies of solid organic semiconductors-I. Structural interpretation of promoted conductivity of salicylaldazine
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Salicylaldazine possesses semiconducting properties, being enhanced by chelation with the d-block elements Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺ Cu²⁺ and Zn²⁺ but not affected by salt formation with Mg²⁺. Promoted conduction could be a consequence of enhanced electron decocalization where the d-shell electrons appear to contribute as charge carrier. Salicylaldazine shows also a phase transition phenomenon, probably associated with two molecular systems which exchange conduction at different thermal stabilities. Chelation or salt formation assists in merging these phases.
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Fluorescence properties of some substituted acyclic azines
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Fluorescence spectra of some acyclic azines (2,3-diazabutadienes), namely ō-hydroxybenzaldizine (1), p̄-N, N-dimethyl-amino abenzaldazine (2) and 2-hydroxy-1-naphthaldazine (3) were determined in different solvents at ambient temperature and at 77 K. The results showed that radiative and nonradiative rates are essentially controlled by the structure of the molecules. The fluorescence of compounds (1)-(3) is enhanced sufficiently by affecting the nπ∗ nature of the S₁ state in different media. The fluorescence quantum yield Φ_F increases significantly as the viscosity of the homogeneous medium increases and as the temperature is lowered to 77 K. However, Φ_F reaches a limiting small value, indicating the existence of an important nonradiative decay channel involving formation of different rotamers and E-Z isomers. The results of quantum chemical calculations based on the Hückel MO method, show that optical excitation decreases bond alternation in the S₁ state, leading to increasing nonradiative decay. Furthermore, the results demonstrate that the photophysical properties of these compounds in an ionic micellar system (CTAB) differ from analogous properties in homogeneous solitions.
Optical excitation of azines containing a hydroxyl group ((1) and (3)) gives rise to a large increase in their acidic properties suggesting that intramolecular proton transfer in these molecules can be switched on by optical excitation.
We have focussed our interest on ō-hydroxybenzaldazine (1) since preliminary studies show that it may be a useful indicator for fluorimetric determination of the microproperties of the surrounding environment.

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¹: 4. Communication; 3. Communication, see Ref. 4.

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Thermochromism and photochromism of aryl substituted acyclic azines1: Uncatalised and acid-catalised thermal isomerisation

Abstract

J. Photochem.

J. Photochem.

Spectrochim. Acta

Liebigs Ann.

Fortschr. chem. Forschg.

J. Chem. Soc. Perkin 1

Z. Chem.

Bull. Soc. Chim. Fr.

J. Am. Chem. Soc.

Bull. Soc. Chim. Fr.

Angew. Chem.

Tetrahedron

J. Chem. Soc. Perkin 2

J. Am. Chem. Soc.

Thermochromism and photochromism of aryl substituted acyclic azines¹: Uncatalised and acid-catalised thermal isomerisation