A photochromic compound: A preparation for the introductory organic laboratory

Ault, Addison; Kouba, Craig

doi:10.1021/ed051p395

Cited by 7 publications

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“…In this study, we have chosen different combinations of ILs along with pure ILs and have investigated the synergism existing between them through photochromic study. Photochromism is the process that involves color changes in a medium by the action of incident electromagnetic radiation. , Although many compounds exhibit photochromic behavior, − the family of spiropyrans is one of the most frequently used compounds in research and technological applications . Spiropyrans are known to exist in two isomeric forms, spiropyran form, SP, and merocyanine form, MC.…”

Section: Results and Discussionmentioning

confidence: 99%

Understanding the Microscopic Behavior of Binary Mixtures of Ionic Liquids through Various Spectroscopic Techniques

et al. 2018

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In recent times, it has been shown that certain binary mixtures of pure ionic liquids having appropriate chemical composition can behave like a new chemical entity. However, current knowledge about the microscopic behavior of these interesting systems is rather limited. The present study is undertaken with an objective to understand the microscopic behavior in terms of intermolecular interaction, structure, and dynamics of these systems. In the present study, few (IL + IL) mixtures are chosen with a common cation and a variation of anion. The investigations are also carried out by taking individual pure ILs so that the difference in the behavior of pure IL and (IL + IL) mixtures is understood. Initially, the systems have been investigated by studying the thermophysical properties of the concerned mixtures. The synergistic effect between combining pure ILs through photochromism has also been studied. These mixtures have been investigated further through steady-state and time-resolved fluorescence spectroscopy, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and fluorescence correlation spectroscopy (FCS). Interestingly, time-resolved fluorescence data also pointed out that (IL + IL) mixtures are not only spatially heterogeneous but also dynamically heterogeneous. EPR measurements have suggested that the micropolarity (E T(30)) of the (IL + IL) mixture is close to that of aliphatic polyalcohols. Measurements of translational diffusion coefficients of the diffusing species through NMR and FCS studies have provided an idea about the nanostructural organization within (IL + IL) binary mixtures. The analysis of data essentially reveals that the mixtures of ILs that are used in the current study do not behave like a nonideal solution. The behavior of the IL mixtures is observed to be more like quasi-ideal type.

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Section: Results and Discussionmentioning

confidence: 99%

Understanding the Microscopic Behavior of Binary Mixtures of Ionic Liquids through Various Spectroscopic Techniques

et al. 2018

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“…Crystals of the photochromic compound, 2-(2,4 dinitrobenzyl)pyridine (α-DNBP) turn a deep blue-violet color when exposed to light of λ = 370-420 nm, providing a visually interesting experiment that has been previously described in this Journal (1)(2)(3)(4). Herein we outline some extensions to the standard experiment.…”

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confidence: 99%

“…Herein we outline some extensions to the standard experiment. These include molecular modeling to study the hydrogen atom migratory distances and the energies for the tautomers arising from the photoinduced proton transfers, 1 H and 13 C NMR spectra, and photobleaching, which demonstrates how light of a different wavelength can reverse the color change. Perhaps equally important is our finding that α-DNBP obtained from the procedures previously published in JCE or purchased commercially would not consistently undergo the color change characteristic of photochromism unless first crystallized from 95% ethanol (4).…”

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Enhancements on the Photochromism of 2-(2,4-Dinitrobenzyl)pyridine: Molecular Modeling, NMR Spectrometry, Photo- and Solvent-Bleaching

et al. 2006

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Molecular-modeling studies on the photochromism of 2-(2,4-dinitrobenzyl)pyridine (α-DNBP), a compound whose synthesis has been previously reported in this Journal, focus on the hydrogen atom migratory distances and the energies for the two very different tautomers arising from the photo-induced proton transfers. Students use these distances to determine the most likely sequence for tautomerization and to explain the relatively slow rate of reversion of the final photoproduct to the original form. They also measure the total energies of the original compound and the two tautomers and examine changes in the geometries that accompany the hydrogen atom migrations. The reason a non-photochromic form of α-DNBP can be found is explained by citing the specific geometric requirements for photochromism in the solid state of an optimal polymorph. The molecular modeling clearly demonstrates the importance of crystal geometric restraints in both the optimal polymorph and the two, diverse photoproducts arising from photo-induced hydrogen atom migrations. The 1H and 13C NMR spectra are reported as well as an experiment that demonstrates photobleaching and solvent-induced bleaching.

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Resonance Raman spectra of short‐lived species of photochromic 2‐ and 4‐(2′,4′‐dinitrobenzyl)pyridine

Takahashi

Kobayashi

Kaneko

et al. 1982

J Raman Spectroscopy

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Resonance Raman spectra of photo-activated transient blue species of 2-(2',4'-dinitrobenzyl)pyridine and 4-(2',4'-dinitrobenzyl)pyridine have been measured in methanol solutions using a dual beam pumplprohe laser technique and a continuous flow method. Comparison of the Raman spectra with those of N-methyl derivatives of both compounds and with those of 1-methyl-2-pyridonemethide and dehydrogenated 5-nitro-o-toluic acid indicates that the transient blue species of both compounds take an N-H quinoid form and not an aci-nitro form. The photo-activated blue species of 4-(2',4'-dinitrobenzyl)pyridine in the molten state is found to be identical with the transient species of the same compound in solution.

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A photochromic compound: A preparation for the introductory organic laboratory

Abstract: The authors describe a preparation for a photochromic compound for the introductory organic laboratory.

Cited by 7 publications

References 0 publications

Understanding the Microscopic Behavior of Binary Mixtures of Ionic Liquids through Various Spectroscopic Techniques

Understanding the Microscopic Behavior of Binary Mixtures of Ionic Liquids through Various Spectroscopic Techniques

Enhancements on the Photochromism of 2-(2,4-Dinitrobenzyl)pyridine: Molecular Modeling, NMR Spectrometry, Photo- and Solvent-Bleaching

Resonance Raman spectra of short‐lived species of photochromic 2‐ and 4‐(2′,4′‐dinitrobenzyl)pyridine

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