(<i>E,E</i>)‐5‐Amino‐2,4‐pentadienal: The First Preparative Synthesis of Hydrolyzed Pyridine

Reinehr, Dieter; Winkler, Tammo

doi:10.1002/anie.198108811

Cited by 8 publications

(4 citation statements)

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“…At the same time, the intensity of the signal at 8.77 ppm, corresponding to the HC=N group, increases in the dark as compared to the signal of pyridine (Figure 2c,d). Notably, the positions and signal-splitting patterns (doublets and triplets, the latter being actually doublets of doublets) are similar to those previously observed for 5-amino-2,4-pentadienal [10] and a series of azapolyenealdehydes in DMSOd6 [18]. In order to gain a deeper insight into the electronic structures of the 5-amino-2,4pentadienal polycondensation products, which are actually oligomers of hitherto unknown polyazaacetylenes, we undertook quantum mechanical calculations [19] on a series of oligomers of 1 (Chart 1) (see Supplementary Materials for the computational details).…”

Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 83%

“…Interestingly, the process is rendered irreversible in the presence of strong basic or acidic media, wherein ammonia and glutaconic acid are produced. A pure sample of 5-amino-2,4-pentadienal was isolated as yellow crystals, which rapidly turned brownish at room temperature and upon exposure to air [10]. The (almost) reversible formation of 5-amino-2,4-pentadienal upon 10 min irradiation at 250 nm of a poly(4-vinyl pyridine)/pyridine/water system was proposed [11] to be responsible for the appearance of a multi-band emission spectrum extending above 600 nm.…”

Section: Introductionmentioning

confidence: 99%

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Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

et al. 2021

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Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals. We show that this light-induced process is only partially reversible, and that the photogenerated aminoaldehyde and aminoaldehyde-pending groups undergo self-condensation to produce cross-linked, conjugated oligomers that absorb light in the visible spectrum up to the near-infrared range. Such a sequence of chemical reactions results in the formation of gel with two distinct morphologies: spheres and fiber-like matrices. To gain deeper insight into this process, we prepared poly(4-vinyl pyridine) with low molecular weight (about 2000 g/mol) and monitored the respective changes in absorption, fluorescence, 1H-NMR spectra, and electrical conductivity. The conductivity of the polymer gel upon irradiation changes from ionic to electronic, indicative of a conjugated molecular wire behavior. Quantum mechanical calculations confirmed the feasibility of the proposed polycondensation process. This new polyacetylene analog has potential in thermal energy-harvesting and sensor applications.

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Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

et al. 2021

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“…The instability of pyridine upon storing on ambient light indicated by appearance of yellow to brownish coloration is well known. Pyridine was shown to produce 5‐amino‐2,4‐pentadienal upon irradiation at 254 nm . This compound is unstable and reverts slowly to pyridine in the dark and cannot be responsible to pyridine coloration.…”

Section: Methodsmentioning

confidence: 99%

What Can Be Learned from the Polymerization of a Pyridine‐Based Two‐Component System

Vaganova¹,

Dubnikov²,

Kesselman

et al. 2019

Macromolecular Symposia

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Stable poly (4‐vinyl pyridine)/pyridine gels prepared by dissolving solid polymer in pyridine (the equimolar ratio of the pyridine moieties to the pyridine solvent molecules) exhibit sensor properties rapidly and reversibly increasing their conductivity upon irradiation by light in the UV‐Vis and NIR ranges. Both ionic and electronic mechanisms of conductivity were detected. The gels behave as polyelectrolytes involving the positively charged pyridine moieties and negatively charged saturated chains held together by a network of hydrogen bonds between the charged and neutral species. This interpretation is corroborated by the cryo‐TEM images of the gel samples resembling chains of beads and the analysis of FT‐IR and 1H‐NMR spectra. Photoinduced proton transfer can thus be responsible for the observed ionic conductivity of the gels. Exposing gels to the ambient light can bring about ring opening of the pyridine moieties and of the free pyridine molecules with subsequent polycondensation of the initially formed 5‐amino‐2,4‐pentadienal. The oligomers of the latter, aza‐analogs of polyacetylene, can serve as molecular wires providing the electronic component of electrical conductivity. These oligomers can also contribute to the ionic conductivity and further stabilize the gels by cross‐linking of the separate polymer chains.

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Sterisch gehinderte Pyridiniumsalze, III. Darstellung und Eigenschaften von N‐Methyl‐[n](2,6)pyridinophaniumsalzen

1985

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Die Titelverbindungen 2a -f konnten durch Alkylierung der [nJ(2,6)Pyridinophane 1 a -f mit Fluorsulfonslure-methylester erstmals dargestellt werden. Sie sind um so alkalilabiler, je kleiner die 2,6-Polymethylenbriicke ist. Im Fall von 2 a konnte 6 als Ringoffnungsprodukt isoliert und charakterisiert werden. Die spektroskopischen Eigenschaften von 2 werden eingehend diskutiert. Die Rontgenstrukturanalyse des Perchlorats von 2b ergab eine angedeutete BriefumschlagKonformation fur den Pyridiniumring, wobei das N-Atom 20 pm auBerhalb der durch die 5 C-Atome gebildeten Ebene liegt. Die 2,6-Heptamethylenbriicke ist so gespannt, daR die Torsionswinkel entlang den C -N-Bindungen bis zu 30" vom Normalwert abweichen. Sterically Hindered Pyridinlum Salts, 1111) Synthesis and Properties of N-Methyl-[n](2,6)pyrdinophanium SaltsThe title compounds 2a-f have been synthesized by alkylation of the corresponding pyridinophanes l a -f with methyl fluorosulfonate. The shorter the 2,6-polymethylene bridge of 2 the greater is the lability in alkaline solution. In the case of 2a the cyclic compound 6 has been isolated and characterized as a ring opened product. The crystal structure of the perchlorate of 2 b has been determined by X-ray diffraction. The pyridinium ring shows an approximate envelope conformation whereby the N-atom is placed 20 pm out of plane of the 5 C-atoms. The heptamethylene bridge is so tight that the torsion angles along the C-N bindings of the pyridinium ring deviate about 30" from the normal value.Die zur Darstellung der Titelverbindung 2 benotigten [n](2,6)Pyridinophane 1 wurden auf dem von Tamao et aLz) erstmals beschriebenen Weg der Cyclisierung von 2,6-Dichlorpyridin mit den entsprechenden Polymethylen-Di-Grignardverbindungen erhalten.Unvollstandige Angaben der Autoren machten es allerdings erforderlich, die Reaktionsbedingungen in verschiedener Hinsicht zu variieren. Ebenso muBte zur Isolierung der Pyridinophane wegen der bendtigten Mengen ein anderes Verfahren als die prtiparative Gaschromatographie gesucht werden.Eine Auftrennung der Reaktionsgemische und die Isolierung der entsprechenden [n](2,6)Pyridinophane wurde mittels SC an Kieselgel und anschlieBender Vakuumdestillation erreicht. Da die physikalischen und spektroskopischen Daten der dargestellten Pyridinophane nur teilweise aus der Literatur" entnommen werden konnten, wur-

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(E,E)‐5‐Amino‐2,4‐pentadienal: The First Preparative Synthesis of Hydrolyzed Pyridine

Cited by 8 publications

References 5 publications

Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

What Can Be Learned from the Polymerization of a Pyridine‐Based Two‐Component System

Sterisch gehinderte Pyridiniumsalze, III. Darstellung und Eigenschaften von N‐Methyl‐[n](2,6)pyridinophaniumsalzen

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