Abstract
C6H7BrN2O2, monoclinic, C2/c (no. 15), a = 23.7470(19) Å, b = 5.4355(4) Å, c = 15.3336(11) Å, β = 127.291(2)°, V = 1574.6(2) Å3, Z = 8, R gt(F) = 0.0292, wR ref(F 2) = 0.0756, T = 150(2) K.
The molecular structure is shown in the figure. Table 1 contains crystallographic data and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters.
Data collection and handling.
| Crystal: | Colorless block |
| Size: | 0.20 × 0.15 × 0.10 mm |
| Wavelength: | Mo Kα radiation (0.71073 Å) |
| μ: | 5.17 mm−1 |
| Diffractometer, scan mode: | Bruker APEX-II, φ and ω |
| θ max, completeness: | 26.4°, >99% |
| N(hkl)measured, N(hkl)unique, R int: | 10,308, 1605, 0.065 |
| Criterion for I obs, N(hkl)gt: | I obs > 2 σ(I obs), 1263 |
| N(param)refined: | 104 |
| Programs: | Bruker [1], Olex2 [2], SHELX [3], [4] |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2).
| Atom | x | y | z | U iso*/U eq |
|---|---|---|---|---|
| Br1 | 0.35629 (2) | 0.70045 (7) | 0.18186 (3) | 0.02907 (13) |
| C1 | 0.35421 (19) | 0.2212 (7) | 0.3494 (3) | 0.0250 (8) |
| C2 | 0.38342 (19) | 0.3998 (7) | 0.4415 (3) | 0.0242 (8) |
| C3 | 0.45042 (19) | 0.4028 (7) | 0.5351 (3) | 0.0263 (8) |
| H3 | 0.483723 | 0.281395 | 0.548937 | 0.032* |
| C4 | 0.46953 (19) | 0.5918 (7) | 0.6117 (3) | 0.0266 (8) |
| H4 | 0.516490 | 0.598262 | 0.677762 | 0.032* |
| C5 | 0.4222 (2) | 0.7632 (7) | 0.5925 (3) | 0.0262 (8) |
| H5 | 0.436086 | 0.890552 | 0.644345 | 0.031* |
| C6 | 0.3517 (2) | 0.7534 (6) | 0.4950 (3) | 0.0245 (8) |
| H1 | 0.391 (3) | −0.027 (9) | 0.325 (4) | 0.049(17)* |
| N1 | 0.30312 (17) | 0.9169 (6) | 0.4716 (2) | 0.0311 (7) |
| H1A | 0.260270 | 0.907483 | 0.409111 | 0.037* |
| H1B | 0.313628 | 1.035041 | 0.518458 | 0.037* |
| N2 | 0.33528 (15) | 0.5722 (5) | 0.4226 (2) | 0.0231 (7) |
| H2 | 0.291958 | 0.564967 | 0.361020 | 0.028* |
| O1 | 0.40101 (15) | 0.0577 (5) | 0.3690 (2) | 0.0333 (7) |
| O2 | 0.29337 (13) | 0.2345 (5) | 0.26787 (19) | 0.0273 (6) |
Source of material
All reagents are purchased from TCI Chemicals and used as received. An amount of 1.38 g of 6-aminopicolinic acid (10 mmol) was added to 10 mL concentrated hydrobromic acid (40%) and stirred for 10 min at room temperature, then filtered, left quietly, and evaporated naturally. Several days later, colorless crystals of 6-amino-2-carboxypyridin-1-ium bromide, C6H7BrN2O2 (ACPB) were obtained, yield 58% (based on 6-aminopicolinic acid).
Experimental details
The structure was solved by direct methods with the SHELXS-2018 program. All H-atoms from C and N atoms were positioned with idealized geometry and refined isotropically (U iso(H) = 1.2U eq(C) and U iso(H) = 1.2U eq(N)) using a riding model with C–H = 0.95 Å and N–H = 0.88 Å. The hydrogen atom at O1 was seen in the Fourier difference map and refined with the distance of O2–H2 = 0.84 Å (U iso(H) = 1.5U eq(O)).
Comment
Known as a multi-functional ligand, 6-aminopicolinic acid was used to construct metal complexes or metal-organic frameworks [5], [6], [7], [8], [9]. We here report the crystal structure of the bromide salt of the 6-aminopicolinic acid, ACPB. ACPB crystallizes in monoclinic system, C2/c group (no. 15). The asymmetric unit is composed of one protonated 6-aminopicolinic acid (2-amino-6-carboxypyridin-1-ium cation) and one bromide anion. The 2-amino-6-carboxypyridin-1-ium cations are linked to each other by N–H⋯Br; O–H⋯Br and N–H⋯O hydrogen bonds, respectively. All of the bond lengths of the ACPB are similar to the reported results [].
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Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
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Research funding: None declared.
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Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
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© 2021 Mengbing Cui et al., published by De Gruyter, Berlin/Boston
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