2-Aminopyridine

Chao, M.; Schemp, E.; Rosenstein, R. D.

doi:10.1107/s0567740875009272

Cited by 91 publications

(40 citation statements)

References 2 publications

(3 reference statements)

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“…1.377 (4) and 1.396 (4) A are significantly longer than the 1.351 (2)A found in 2-aminopyridine (Chao, Schempp & Rosenstein, 1975a, which is near to the average value in the five substituted 2-aminopyridines. A single amino group adjacent to a ring N atom in a n-deficient heterocycle is expected to show sp 2 hybridization and to make a significant contribution of p electrons to the n system, thus increasing the bond order and shortening the length of its connection to the ring.…”

Section: H2~ Nh2mentioning

confidence: 52%

A neutron diffraction study of 2,6-diaminopyridine at 20 K

Schwalbe¹,

Williams²,

Koetzle³

1987

Acta Crystallogr C

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Section: H2~ Nh2mentioning

confidence: 52%

A neutron diffraction study of 2,6-diaminopyridine at 20 K

Schwalbe¹,

Williams²,

Koetzle³

1987

Acta Crystallogr C

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“…In 2AP itself, Kydd and Mills (20) established that the angle between the plane made by the NH 2 group and the ring is nearly 32°in the gas phase. In the crystal structure (22), this angle is reduced to Ϸ15°. This difference indicates that the geometry of the NH 2 group highly depends on the local environment of the molecule.…”

Section: Discussionmentioning

confidence: 99%

“…r 1 and r2 are the hydrogen bond distances N⅐⅐⅐HON and NOH⅐⅐⅐O, and is the (nonzero) dihedral angle. Table 2 compares the experimental values of the hydrogen bond lengths in ground-state 2AP⅐2PY with theoretical estimates (16) and with experimental values for the 2AP dimer (22), the 2PY dimer (23), and the Watson-Crick A⅐T base pair found in sodium adenylyl-3Ј,5Ј-uridine (SAU) by Seeman et al (24). The latter experimental values are based on x-ray diffraction studies of crystals.…”

Section: Discussionmentioning

confidence: 99%

Base pair analogs in the gas phase

Roscioli

Pratt

2003

Proc. Natl. Acad. Sci. U.S.A.

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A rotationally resolved electronic spectrum of the gas-phase dimer 2-aminopyridine⅐2-pyridone, an analog of the adenine⅐thymine base pair, has been observed and assigned, leading to precise measurements of its moments of inertia and preliminary determinations of its structure. A Watson-Crick configuration results, with N⅐⅐⅐HON and NOH⅐⅐⅐O hydrogen bond lengths of 2.898 and 2.810 Å, respectively. The two bases are found not to be coplanar; a dihedral angle of 6.1°between the base planes is also estimated from the measured moments of inertia. Possible chemical and biological implications of these results are discussed. F ifty years have elapsed since x-ray diffraction photographs of fibers pulled from concentrated solutions of DNA revealed that its structure is a double-stranded helix held together by hydrogen bonds between the complementary base pairs adenine (A) and thymine (T), and guanine (G) and cytosine (C) (1-3), providing a molecular-level explanation of heredity (4). Despite this passage of time, the structure of an isolated A⅐T or G⅐C base pair in the absence of solvent and͞or a surrounding medium has yet to be determined. Only the average structure of the base pairs in the condensed phase can be determined from fiber-diffraction patterns of DNA. To be sure, we now know that many different kinds of DNA exist and that, although they share many common features, they can differ significantly in detail. These differences include the number of residues per turn, the translation per residue, the angle between the base planes and the helix axis, and the dihedral angle between base planes (5). We also know that these features may be functionally important, both in gene expression and in the construction of the cell (6), but we do not know the extent to which the differences in DNA structures are a consequence of the condensed-phase environment in which they are found. Gas-phase studies are needed not only to provide benchmark structures but also to quantify the relative importance of intra-and intermolecular interactions in molecular biology.Toward this end, we report here a preliminary determination of the structure of the base-pair mimic 2-aminopyridine⅐2-pyridone (2AP⅐2PY) by using the technique of rotationally resolved electronic spectroscopy in the gas phase. 2AP⅐2PY is found to be held together by two N⅐⅐⅐HON and NOH⅐⅐⅐O hydrogen bonds, identical with those found in the A⅐T base pair itself. As will be seen, understanding the nature of these interactions provides insight into the structure, stability, and electronic properties of the bonds that hold DNA together. MethodsOur experiments were performed in the collision-free environment of a molecular beam (7). Approximately 1 g of 2AP was placed in a quartz sample container at nearly 200°C and entrained in 41 kPa (6 psig) of He. After equilibrium was established, Ϸ2 g of 2PY was added to the sample container, and the spectrum of the 2AP⅐2PY dimer appeared shortly thereafter. During this time, the mixture was expanded through a 280-m quartz nozzle held at 150...

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“…2). The structure is similar to the crystal structures of, for instance, 2-amino-5-chloropyridine (Kvick & Back~us, 1974) and 2-amino-4-methylpyridine (Kvick & (2) 1.400 (2) 1.365 (2) 1.393 (2) 1.375 (2) 1.506 (2) 1-405 (7) 1.357 (7) 1.397 (7) 1.353 (7) i-494 (7) 1.408 (2) 1.368 (2) 1-389 (2) 1.377 (2) -1.399 (4) 1.391 (4) 1.376 (4) 1.372 (4) References: (I) Chao, Schempp & Rosenstein (1975, 1976. (2) Destro, Pilati & Simonetta (1975).…”

mentioning

confidence: 99%

“…The thermal ellipsoids are scaled to 30% probability except for the H atoms, which are represented by spheres of radius 0.15 A. (Chao, Schempp & Rosenstein, 1975, 1976.…”

mentioning

confidence: 99%