Über Nitrierungsprodukte des α‐ und des γ‐ Benzyl‐pyridins

Tschitschibabin, A. E.; Kuindshi, B. M.; Benewolenskaja, S. W.

doi:10.1002/cber.19250580832

Cited by 60 publications

(26 citation statements)

References 2 publications

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“…Upon irradiation with ultraviolet light (UV), a blue coloured tautomer is formed. The original discovery of the photochromism of this molecule dates back to Chichababin et al [2]. Subsequently, different structural assignments of the phototautomer have been proposed and discussed, and details of the reaction mechanism continue to be the object of ongoing work [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…For example, the lifetime in the solid (a few hours) is much longer than in solution (16 s in ethanol solution at 280 K). Scheme 1 shows the proposed reaction mechanism and the tautomers of α-DNBP: the thermodynamically stable 'CH' (1) state and the 'NH' (2) and 'OH' (3) tautomers, identified as the reaction intermediates both in solutions [3 and references therein] and in the crystalline state [7,8]. Figure 1.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nuclear magnetic resonance spectroscopy studies of 2-(2,4-dinitrobenzyl) pyridine and long-lived photoinduced products

Nunes

Eichen

Bastos

et al. 1999

J. Phys. D: Appl. Phys.

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A study of the photo-induced and thermally activated tautomerization of 2-(2,4-dinitrobenzyl) pyridine (α-DNBP) by solid state nuclear magnetic resonance spectroscopy (NMR) is presented. Whereas similar high-resolution 1 H and 13 C spectra were obtained from polycrystalline powders before and after ultraviolet light irradiation, the corresponding spectral data obtained from PVC films doped with α-DNBP show significant changes. The α-DNBP phototautomer lifetimes in PVC films (2.4 h or 6 d) were determined from the proton NMR signal recovery. Scanning electron microscopy (SEM) and differential scanning calorimetry of the doped films show that, in addition to matrix isolated molecules, α-DNBP is incorporated into the polymer matrix in the form of nanocrystalline aggregates. At high guest concentrations, the crystallites can be modified by controlled solvent evaporation, as monitored by NMR and SEM. The variation of the 1 H spectrum with temperature shows the presence of at least two stable conformational isomers in the solid samples.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nuclear magnetic resonance spectroscopy studies of 2-(2,4-dinitrobenzyl) pyridine and long-lived photoinduced products

Nunes

Eichen

Bastos

et al. 1999

J. Phys. D: Appl. Phys.

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“…Further, we discovered that the author did not mention earlier publications concerning this substance [9,10]. It is remarkable that Tschitschibabin et al described the investigated compound as early as 1925 [11]. Figure 3, line a shows the Raman spectrum of the darkadapted, yellow 2-(2′,4′-dinitrobenzyl)pyridine crystals and Fig.…”

Section: Photochemistrymentioning

confidence: 93%

Non-destructive NIR-FT-Raman analyses in practice. Part II. Analyses of 'jumping' crystals, photosensitive crystals and gems

Andreev

Schräder

Boese

et al. 2001

Fresenius' Journal of Analytical Chemistry

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Using an improved sampling arrangement we observed the FT Raman spectra of the different phases of a 'jumping crystal', an inositol derivative. The phase transition produced -as consequences of large changes of the unit cell constants -changes in frequency and intensity mainly of CH deformation vibrations. Photochemical reactions, usually produced with light quanta in the visible range, are not activated with the quanta from the Nd:YAG laser at 1064 nm. The Raman spectra of the 'dark' form of a dinitrobenzyl pyridine and afterwards the 'light' form, the product of its illumination in the visible range, were recorded. We could not observe changes of most bands, especially not of the NO 2 -vibrations; however, a new strong band appeared at 1253 cm -1 , which may be due to the expected NH-photo-isomer. Genuine gemstones and fakes can be unambiguously identified by FT Raman spectroscopy. This is especially useful for the stones whose physical properties are quite similar to those of diamonds -moissanite and zirconia. The quality of diamonds can be estimated from relative band intensities; however, this is not in complete agreement with the internationally accepted visual qualification. Synthetic diamonds produced by CVD (chemical vapor deposition) show remarkable differences from natural ones in their FT-Raman spectra.

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“…In 1925 Tschitschibabin et al . observed the photochromic behavior of 2‐(2,4‐dinitrobenzyl)pyridine (DNBP) 1 1. The pale yellow crystals dye blue by exposure to sunlight and slowly fade back to yellow in the dark.…”

Section: Introductionmentioning

confidence: 96%

Synthesis and properties of di‐ and trinitrobenzyl substituted pyridine derivates

Frej¹,

Goeschen²,

Näther³

et al. 2010

J of Physical Organic Chem

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A new method to obtain di‐ and trinitrobenzyl substituted pyridines is presented in this paper. By systematic variation of reaction parameters, the reaction conditions were optimized. The novel synthesis circumvents the commonly used nitration of benzyl pyridines, and thus avoids the nitration of the heterocycle which is a common side reaction. Furthermore, the starting materials for the synthesis of a variety of photochromic nitrobenzyl pyridines are easily accessible. The half‐lives of the phototautomers of several new di‐ and trinitrobenzyl‐substituted pyridines were determined. Copyright © 2010 John Wiley & Sons, Ltd.

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Über Nitrierungsprodukte des α‐ und des γ‐ Benzyl‐pyridins

Cited by 60 publications

References 2 publications

Nuclear magnetic resonance spectroscopy studies of 2-(2,4-dinitrobenzyl) pyridine and long-lived photoinduced products

Nuclear magnetic resonance spectroscopy studies of 2-(2,4-dinitrobenzyl) pyridine and long-lived photoinduced products

Non-destructive NIR-FT-Raman analyses in practice. Part II. Analyses of 'jumping' crystals, photosensitive crystals and gems

Synthesis and properties of di‐ and trinitrobenzyl substituted pyridine derivates

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