Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270113017484/qs3026sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113017484/qs3026Isup2.hkl | |
Chemical Markup Language (CML) file https://doi.org/10.1107/S0108270113017484/qs3026Isup3.cml |
CCDC reference: 963383
Dipeptides form nanoporous structures belonging to three different classes (Görbitz, 2007): the Val–Ala class with hydrophobic pores (all amino acids discussed in this paper are of the L configuration, stereochemical indicators are thus not included), the Phe–Phe class with hydrophilic pores, and, with just a single member, the Leu–Ser class with hydrophobic pores [Görbitz et al., 2005; Cambridge Structural Database (CSD; Allen, 2002) refcode JAZBOC]. Val–Ser (Görbitz, 2005a; Johansen et al., 2005) and Ile–Ser (Görbitz et al., 2006) were subsequently investigated in the search for additional Leu–Ser class structures, but yielded other types of structure. A careful analysis of the Leu–Ser crystal packing then revealed that it is in fact incompatible with side-chain branching at Cβ, as this would inevitably lead to steric conflict with main-chain atoms. Met–Ser (Görbitz et al., 2006) furthermore produced a layered packing arrangement (obtained as a 0.34-hydrate). Consequently, additional members of the Leu–Ser family, preferentially with even wider channels, had to be sought among dipeptides with other hydrophobic and unbranched side chains at the N-terminal end. We have now synthesized two new dipeptides with nonproteinogenic amino acid residues: Nva–Ser (Nva = norvaline) with an n-propyl side chain and Abu–Ser, (I) (Abu = 2-aminobutyric acid), with an ethyl side chain. Attempts to grow crystals from Nva–Ser were, unfortunately, uniformly unsuccessful, but (I) yielded small crystals of reasonable quality that permitted a single-crystal X-ray diffraction analysis.
Crystal data, data collection and structure refinement details are summarized in Table 1.
The title compound was prepared by solution-phase reaction processes, described in the Supplementary materials [Not available?]. Fine crystals were grown by adding a few drops of dimethylformamide to an aqueous solution (10 ml) of (I) (0.275 g), with subsequent slow evaporation at room temperature.
During the review process of this paper, concerns were raised as to whether the complex molecular disorder could in fact be an artifact resulting from crystal twinning. The diffraction patterns at 105 K looked perfectly normal, with no indication of peak splitting, unindexed peaks or other signs of nonmerohedral twinning. It is important to note that we can safely assume the basic packing arrangement and hydrogen-bonding network to be correct, and that, due to prohibitive steric conflict, disorder would also persist in lower symmetry space groups for both Abu and Ser side-chain columns. This was subsequently demonstrated by solving the structure in the monoclinic space group C2 [a = 25.833 (7), b = 5.1328 (15), c = 18.303 (9) Å, β = 134.86 (2)°, Rint = 0.060] with Z' = 2, both molecules showing exactly the same type of disorder, as indicated for the single I4 molecule in Fig. 1, with no improvement in the R factor [= 0.086 for a slightly more crude disorder model for the C-terminal residue than applied for (I)]. Furthermore, a new data set collected with Cu radiation (λ = 1.542 Å) confirmed that the space group is also I4 at room temperature [a = b = 18.3287 (10) and c = 5.1461 (4) Å], thus ruling out the possibilty of a phase transition taking place during cooling from 295 K to the 105 K used for data collection for (I).
N—H and C—H bond lengths were fixed at 0.91 (NH3+), 0.88 (>N—H), 0.98 (CH3), 0.99 (CH2) or 1.00 (CH) Å (default SHELXTL values at 105 K; Sheldrick, 2008), with rotation permitted for the amino group. Uiso values were 1.5Ueq of the carrier atom for hydroxy, amino and methyl groups, and 1.2Ueq for other H atoms. Heavy-atom disorder was evident for the Abu side chain (two components), as well as for the Ser residue, for which the main-chain atoms, although at short separation, were also included in a disorder model with three components (see Fig. 1). The combination of tetragonal symmetry, extensive disorder and a small crystal with rather weak diffraction put pressure on the reflection-to-parameter ratio. In order not to compromise this ratio further, a number of measures were taken to limit the number of refinement parameters: (i) refinement of a single isotropic displacement parameter for atoms C21 and C22, and for atoms C61, C62 and C63; (ii) applying the same set of anisotropic displacement parameters for equivalent main-chain atoms affected by disorder, e.g. N21, N22 and N23; (iii) use of SHELXTL AFIX 83 commands for hydroxy H atoms, which uses the best staggered position considering the available hydrogen-bond acceptors. As the electron density associated with the three positions for the Ser Cβ atoms was large and diffuse, appropriate restraints were introduced for the geometry of this side chain. In the absence of significant anomalous scattering effects, 865 Friedel pairs were merged.
The molecular structure (Fig. 1) and the crystal packing arrangement (Fig. 2d) show that (I) does not belong to the Leu–Ser class, but instead is a close mimic of the structure of Ala–Ala (CSD refcode ALAALA; Fletterick et al., 1970) shown in Fig. 2(a), which has a three-dimensional hydrogen-bonding network and tetragonal symmetry (space group I4). Hydrophobic columns generated by the methyl groups of the N-terminal residues of Ala–Ala are located on regular fourfold rotation axes, while the methyl groups of the C-terminal residues build independent columns with 42 screw symmetry. The former has a series of small voids along the c axis (Fig. 2b). These do not take the shape of a continuous channel, but at high pressure the crystals are nevertheless permeable to O2 (but not to N2; Afonso et al., 2010).
We have previously shown that the tetragonal unit cell of Ala–Ala is incompatible with an ethyl side chain at the second residue, as Ala–Abu takes on a completely different crystal-packing arrangement with lower density, both for the hydrate obtained from an aqueous solution (1.282 Mg m-3; Görbitz, 2002) and for the related nonhydrate from a 1,1,1,3,3,3-hexafluoropropan-2-ol solution (1.244 Mg m-3; Görbitz, 2005b). I4 symmetry is, on the other hand, retained for Abu–Ala (XOSHOC; Görbitz, 2002) (Fig. 2c), for which the additional side-chain methyl groups essentially fill the voids of the Ala–Ala structure at the fourfold axes (Fig. 2c). This close packing of ethyl side chains implies the introduction of disorder to avoid steric conflict, with an even distribution between two side-chain conformations (gauche- and gauche+). The same type of disorder occurs for the Abu residue of (I), as shown in Fig. 1 and Fig. 2(d) and in detail in Fig. 3(a). The torsion angles listed in Table 2 reveal, as for Abu–Ala, substantial deviations from idealized staggered gauche conformations at ±60° for N1—C11/C12—C21/C22—C31/C32, suggesting a very crowded environment for the Abu side chain.
The surprising aspect of the structure of (I) is that it exists at all, that is that the densely packed hydrophobic columns of the second residue in Ala–Ala (Fig. 2a) can in fact adapt to accommodate the significantly larger Ser side chain (Fig. 2c) without disrupting the entire structure. This is rendered possible by a slight increase in unit-cell volume (Table 3), but most of all by a remarkably tight stacking of Ser side chains, resulting in a high-density structure. Furthermore, as seen in Fig. 1, the Ser side chain is disordered over three positions. The major position, with N—C—C—O = gauche-, forms what appears to be a hydrogen-bonded ring in the projection in Fig. 2(d), but actually is a right-handed helix (Fig. 3b). The occupancies of the O21 atoms involved in these chains are sterically limited to 1/2, so half of the serine side chains need to use two other conformations. These are distributed randomly along the fourfold screw axis, as illustrated in Fig. 3(b), and may donate H atoms to main-chain carboxylate acceptors when N—C—C—O is gauche+ [occupancy 0.299 (9), violet atom O22 in all illustrations] or to other Ser OH groups when N—C—C—O is trans [occupancy 0.201 (9), O23 orange]. Hydrogen-bond data are given in Table 4.
In addition to the three structures shown in Fig. 2, Ala–Ser could, from the observations made here, be a potential member of the Ala–Ala group. However, a tetragonal polymorph has not been observed, as this dipeptide forms monoclinic crystals with exceptionally high density (1.566 Mg m-3) and a compact three-dimensional hydrogen-bonding pattern (Jones et al., 1978).
In conclusion, in the absence of a crystal structure for Nva–Ser (see above), it appears that Leu-Ser is indeed the sole member of its own class of nanoporous dipeptide structures.
Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
C7H14N2O4 | Dx = 1.462 Mg m−3 |
Mr = 190.20 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, I4 | Cell parameters from 2704 reflections |
Hall symbol: I 4 | θ = 3.1–25.1° |
a = 18.335 (7) Å | µ = 0.12 mm−1 |
c = 5.141 (2) Å | T = 105 K |
V = 1728.1 (12) Å3 | Needle, colourless |
Z = 8 | 0.39 × 0.09 × 0.06 mm |
F(000) = 816 |
Bruker APEXII CCD area-detector diffractometer | 862 independent reflections |
Radiation source: fine-focus sealed tube | 780 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.084 |
Detector resolution: 8.3 pixels mm-1 | θmax = 25.1°, θmin = 2.2° |
Sets of exposures each taken over 0.5° ω rotation scans | h = −21→21 |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | k = −21→21 |
Tmin = 0.788, Tmax = 0.993 | l = −6→6 |
6072 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.080 | H-atom parameters constrained |
wR(F2) = 0.195 | w = 1/[σ2(Fo2) + (0.0359P)2 + 9.6883P] where P = (Fo2 + 2Fc2)/3 |
S = 1.30 | (Δ/σ)max < 0.001 |
862 reflections | Δρmax = 0.38 e Å−3 |
177 parameters | Δρmin = −0.30 e Å−3 |
767 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.014 (3) |
C7H14N2O4 | Z = 8 |
Mr = 190.20 | Mo Kα radiation |
Tetragonal, I4 | µ = 0.12 mm−1 |
a = 18.335 (7) Å | T = 105 K |
c = 5.141 (2) Å | 0.39 × 0.09 × 0.06 mm |
V = 1728.1 (12) Å3 |
Bruker APEXII CCD area-detector diffractometer | 862 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 780 reflections with I > 2σ(I) |
Tmin = 0.788, Tmax = 0.993 | Rint = 0.084 |
6072 measured reflections |
R[F2 > 2σ(F2)] = 0.080 | 767 restraints |
wR(F2) = 0.195 | H-atom parameters constrained |
S = 1.30 | Δρmax = 0.38 e Å−3 |
862 reflections | Δρmin = −0.30 e Å−3 |
177 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
N1 | 0.7087 (2) | 0.6819 (2) | 0.7119 (15) | 0.0311 (11) | |
H1 | 0.6725 | 0.6973 | 0.8197 | 0.047* | |
H2 | 0.6991 | 0.6967 | 0.5466 | 0.047* | |
H3 | 0.7520 | 0.7012 | 0.7650 | 0.047* | |
C11 | 0.7132 (3) | 0.6013 (2) | 0.7194 (13) | 0.0211 (10) | 0.50 |
H111 | 0.7400 | 0.5872 | 0.8810 | 0.025* | 0.50 |
C21 | 0.6400 (4) | 0.5606 (6) | 0.718 (3) | 0.0210 (16)* | 0.50 |
H21A | 0.6480 | 0.5090 | 0.6684 | 0.025* | 0.50 |
H21B | 0.6070 | 0.5829 | 0.5876 | 0.025* | 0.50 |
C31 | 0.6028 (5) | 0.5647 (6) | 1.005 (2) | 0.031 (3) | 0.50 |
H31A | 0.5552 | 0.5405 | 1.0010 | 0.046* | 0.50 |
H31B | 0.5965 | 0.6158 | 1.0555 | 0.046* | 0.50 |
H31C | 0.6344 | 0.5401 | 1.1315 | 0.046* | 0.50 |
C12 | 0.7132 (3) | 0.6013 (2) | 0.7194 (13) | 0.0211 (10) | 0.50 |
H121 | 0.7384 | 0.5861 | 0.8831 | 0.025* | 0.50 |
C22 | 0.6340 (4) | 0.5741 (7) | 0.726 (3) | 0.0210 (16)* | 0.50 |
H22A | 0.6032 | 0.6092 | 0.8221 | 0.025* | 0.50 |
H22B | 0.6316 | 0.5265 | 0.8169 | 0.025* | 0.50 |
C32 | 0.6037 (5) | 0.5651 (7) | 0.430 (2) | 0.031 (3) | 0.50 |
H32A | 0.5556 | 0.5418 | 0.4333 | 0.046* | 0.50 |
H32B | 0.6375 | 0.5348 | 0.3293 | 0.046* | 0.50 |
H32C | 0.5997 | 0.6133 | 0.3483 | 0.046* | 0.50 |
O1 | 0.77388 (19) | 0.6190 (2) | 0.3075 (12) | 0.0296 (9) | |
C4 | 0.7587 (3) | 0.5762 (3) | 0.4841 (14) | 0.0244 (11) | |
N21 | 0.7773 (7) | 0.5008 (13) | 0.491 (5) | 0.0259 (15) | 0.50 |
H4 | 0.7662 | 0.4749 | 0.6299 | 0.031* | 0.50 |
C51 | 0.8142 (5) | 0.4657 (6) | 0.274 (3) | 0.0283 (14) | 0.50 |
H51 | 0.8262 | 0.5040 | 0.1424 | 0.034* | 0.50 |
C61 | 0.8855 (5) | 0.4295 (4) | 0.361 (3) | 0.035 (2)* | 0.50 |
H61A | 0.8749 | 0.3937 | 0.4998 | 0.042* | 0.50 |
H61B | 0.9069 | 0.4027 | 0.2118 | 0.042* | 0.50 |
O21 | 0.9372 (4) | 0.4813 (5) | 0.454 (2) | 0.057 (3) | 0.50 |
H21 | 0.9439 | 0.5136 | 0.3410 | 0.085* | 0.50 |
C71 | 0.7629 (7) | 0.4096 (7) | 0.146 (4) | 0.0222 (15) | 0.50 |
O31 | 0.7316 (7) | 0.4247 (9) | −0.060 (3) | 0.031 (2) | 0.50 |
O41 | 0.7530 (13) | 0.3497 (8) | 0.268 (4) | 0.030 (2) | 0.50 |
N22 | 0.7773 (10) | 0.5120 (12) | 0.480 (5) | 0.0259 (15) | 0.299 (9) |
H5 | 0.7633 | 0.4855 | 0.6142 | 0.031* | 0.299 (9) |
C52 | 0.8195 (8) | 0.4740 (7) | 0.283 (3) | 0.0283 (14) | 0.299 (9) |
H52 | 0.8255 | 0.5078 | 0.1322 | 0.034* | 0.299 (9) |
C62 | 0.8956 (6) | 0.4535 (10) | 0.380 (3) | 0.035 (2)* | 0.299 (9) |
H62A | 0.9177 | 0.4181 | 0.2577 | 0.042* | 0.299 (9) |
H62B | 0.9267 | 0.4976 | 0.3812 | 0.042* | 0.299 (9) |
O22 | 0.8946 (7) | 0.4226 (7) | 0.634 (2) | 0.042 (4) | 0.299 (9) |
H22 | 0.8518 | 0.4103 | 0.6723 | 0.064* | 0.299 (9) |
C72 | 0.7775 (12) | 0.4065 (10) | 0.187 (4) | 0.0222 (15) | 0.299 (9) |
O32 | 0.7439 (16) | 0.4090 (12) | −0.023 (4) | 0.031 (2) | 0.299 (9) |
O42 | 0.7745 (11) | 0.3518 (8) | 0.341 (4) | 0.030 (2) | 0.299 (9) |
N23 | 0.770 (2) | 0.502 (3) | 0.495 (10) | 0.0259 (15) | 0.201 (9) |
H6 | 0.7470 | 0.4770 | 0.6160 | 0.031* | 0.201 (9) |
C53 | 0.8176 (11) | 0.4623 (13) | 0.318 (6) | 0.0283 (14) | 0.201 (9) |
H53 | 0.8388 | 0.4980 | 0.1923 | 0.034* | 0.201 (9) |
C63 | 0.8806 (12) | 0.4256 (15) | 0.464 (4) | 0.035 (2)* | 0.201 (9) |
H63A | 0.9142 | 0.4636 | 0.5305 | 0.042* | 0.201 (9) |
H63B | 0.8609 | 0.3986 | 0.6154 | 0.042* | 0.201 (9) |
O23 | 0.9201 (10) | 0.3765 (10) | 0.302 (5) | 0.047 (6) | 0.201 (9) |
H23 | 0.9236 | 0.3942 | 0.1515 | 0.070* | 0.201 (9) |
C73 | 0.7731 (18) | 0.4059 (18) | 0.163 (7) | 0.0222 (15) | 0.201 (9) |
O33 | 0.751 (3) | 0.421 (3) | −0.058 (6) | 0.031 (2) | 0.201 (9) |
O43 | 0.762 (3) | 0.344 (2) | 0.273 (10) | 0.030 (2) | 0.201 (9) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.023 (2) | 0.033 (2) | 0.037 (3) | 0.0007 (17) | 0.005 (2) | −0.003 (2) |
C11 | 0.025 (2) | 0.027 (2) | 0.011 (2) | −0.0015 (17) | −0.0046 (18) | 0.000 (2) |
C31 | 0.037 (5) | 0.036 (5) | 0.021 (5) | 0.004 (4) | 0.008 (4) | −0.009 (4) |
C12 | 0.025 (2) | 0.027 (2) | 0.011 (2) | −0.0015 (17) | −0.0046 (18) | 0.000 (2) |
C32 | 0.028 (5) | 0.042 (5) | 0.022 (5) | −0.009 (4) | 0.001 (4) | −0.004 (4) |
O1 | 0.039 (2) | 0.0363 (19) | 0.0131 (18) | −0.0033 (16) | 0.0026 (18) | 0.0036 (17) |
C4 | 0.026 (2) | 0.029 (2) | 0.018 (2) | −0.0009 (19) | −0.003 (2) | 0.003 (2) |
N21 | 0.033 (3) | 0.025 (2) | 0.019 (2) | −0.002 (2) | 0.004 (2) | 0.000 (2) |
C51 | 0.034 (2) | 0.027 (2) | 0.024 (3) | −0.0016 (18) | 0.008 (2) | 0.001 (2) |
O21 | 0.053 (4) | 0.053 (5) | 0.064 (6) | −0.015 (4) | −0.012 (5) | −0.002 (5) |
C71 | 0.020 (3) | 0.027 (2) | 0.020 (3) | 0.006 (2) | 0.004 (2) | 0.000 (2) |
O31 | 0.035 (5) | 0.034 (4) | 0.026 (3) | 0.003 (4) | −0.003 (3) | 0.007 (2) |
O41 | 0.032 (5) | 0.026 (2) | 0.032 (4) | 0.003 (3) | 0.003 (3) | 0.006 (2) |
N22 | 0.033 (3) | 0.025 (2) | 0.019 (2) | −0.002 (2) | 0.004 (2) | 0.000 (2) |
C52 | 0.034 (2) | 0.027 (2) | 0.024 (3) | −0.0016 (18) | 0.008 (2) | 0.001 (2) |
O22 | 0.047 (6) | 0.043 (6) | 0.037 (7) | 0.001 (5) | 0.001 (5) | 0.003 (5) |
C72 | 0.020 (3) | 0.027 (2) | 0.020 (3) | 0.006 (2) | 0.004 (2) | 0.000 (2) |
O32 | 0.035 (5) | 0.034 (4) | 0.026 (3) | 0.003 (4) | −0.003 (3) | 0.007 (2) |
O42 | 0.032 (5) | 0.026 (2) | 0.032 (4) | 0.003 (3) | 0.003 (3) | 0.006 (2) |
N23 | 0.033 (3) | 0.025 (2) | 0.019 (2) | −0.002 (2) | 0.004 (2) | 0.000 (2) |
C53 | 0.034 (2) | 0.027 (2) | 0.024 (3) | −0.0016 (18) | 0.008 (2) | 0.001 (2) |
O23 | 0.047 (7) | 0.049 (8) | 0.044 (9) | 0.010 (5) | 0.010 (7) | −0.002 (7) |
C73 | 0.020 (3) | 0.027 (2) | 0.020 (3) | 0.006 (2) | 0.004 (2) | 0.000 (2) |
O33 | 0.035 (5) | 0.034 (4) | 0.026 (3) | 0.003 (4) | −0.003 (3) | 0.007 (2) |
O43 | 0.032 (5) | 0.026 (2) | 0.032 (4) | 0.003 (3) | 0.003 (3) | 0.006 (2) |
N1—C11 | 1.480 (6) | C61—O21 | 1.425 (3) |
N1—H1 | 0.9100 | C61—H61A | 0.9900 |
N1—H2 | 0.9100 | C61—H61B | 0.9900 |
N1—H3 | 0.9100 | O21—H21 | 0.8400 |
C11—C21 | 1.535 (7) | C71—O31 | 1.239 (8) |
C11—C4 | 1.541 (7) | C71—O41 | 1.279 (7) |
C11—H111 | 1.0000 | N22—C52 | 1.452 (3) |
C21—C31 | 1.629 (17) | N22—H5 | 0.8800 |
C21—H21A | 0.9900 | C52—C62 | 1.529 (3) |
C21—H21B | 0.9900 | C52—C72 | 1.540 (8) |
C31—H31A | 0.9800 | C52—H52 | 1.0000 |
C31—H31B | 0.9800 | C62—O22 | 1.425 (3) |
C31—H31C | 0.9800 | C62—H62A | 0.9900 |
C22—C32 | 1.629 (17) | C62—H62B | 0.9900 |
C22—H22A | 0.9900 | O22—H22 | 0.8400 |
C22—H22B | 0.9900 | C72—O32 | 1.240 (8) |
C32—H32A | 0.9800 | C72—O42 | 1.279 (7) |
C32—H32B | 0.9800 | N23—C53 | 1.454 (3) |
C32—H32C | 0.9800 | N23—H6 | 0.8800 |
O1—C4 | 1.231 (7) | C53—C63 | 1.532 (3) |
C4—N22 | 1.226 (19) | C53—C73 | 1.541 (8) |
C4—N23 | 1.38 (6) | C53—H53 | 1.0000 |
C4—N21 | 1.42 (2) | C63—O23 | 1.426 (3) |
N21—C51 | 1.454 (3) | C63—H63A | 0.9900 |
N21—H4 | 0.8800 | C63—H63B | 0.9900 |
C51—C61 | 1.532 (3) | O23—H23 | 0.8400 |
C51—C71 | 1.542 (8) | C73—O33 | 1.239 (8) |
C51—H51 | 1.0000 | C73—O43 | 1.279 (7) |
N1—C11—C21 | 115.9 (6) | O21—C61—H61A | 109.2 |
N1—C11—C4 | 107.9 (4) | C51—C61—H61A | 109.2 |
C21—C11—C4 | 108.9 (7) | O21—C61—H61B | 109.2 |
N1—C11—H111 | 107.9 | C51—C61—H61B | 109.2 |
C21—C11—H111 | 107.9 | H61A—C61—H61B | 107.9 |
C4—C11—H111 | 107.9 | C61—O21—H21 | 109.5 |
C11—C21—C31 | 109.8 (9) | O31—C71—O41 | 123.2 (7) |
C11—C21—H21A | 109.7 | O31—C71—C51 | 120.0 (6) |
C31—C21—H21A | 109.7 | O41—C71—C51 | 116.8 (6) |
C11—C21—H21B | 109.7 | C4—N22—C52 | 128 (2) |
C31—C21—H21B | 109.7 | C4—N22—H5 | 115.9 |
H21A—C21—H21B | 108.2 | C52—N22—H5 | 115.9 |
C21—C31—H31A | 109.5 | N22—C52—C62 | 112.1 (3) |
C21—C31—H31B | 109.5 | N22—C52—C72 | 110.2 (5) |
H31A—C31—H31B | 109.5 | C62—C52—C72 | 111.3 (5) |
C21—C31—H31C | 109.5 | N22—C52—H52 | 107.7 |
H31A—C31—H31C | 109.5 | C62—C52—H52 | 107.7 |
H31B—C31—H31C | 109.5 | C72—C52—H52 | 107.7 |
C32—C22—H22A | 109.8 | O22—C62—C52 | 112.5 (4) |
C32—C22—H22B | 109.8 | O22—C62—H62A | 109.1 |
H22A—C22—H22B | 108.2 | C52—C62—H62A | 109.1 |
C22—C32—H32A | 109.5 | O22—C62—H62B | 109.1 |
C22—C32—H32B | 109.5 | C52—C62—H62B | 109.1 |
H32A—C32—H32B | 109.5 | H62A—C62—H62B | 107.8 |
C22—C32—H32C | 109.5 | C62—O22—H22 | 109.5 |
H32A—C32—H32C | 109.5 | O32—C72—O42 | 123.0 (7) |
H32B—C32—H32C | 109.5 | O32—C72—C52 | 119.9 (6) |
N22—C4—O1 | 122.5 (14) | O42—C72—C52 | 116.8 (6) |
N22—C4—N23 | 8 (3) | C4—N23—C53 | 124 (4) |
O1—C4—N23 | 129 (2) | C4—N23—H6 | 118.0 |
N22—C4—N21 | 3.3 (19) | C53—N23—H6 | 118.0 |
O1—C4—N21 | 125.7 (11) | N23—C53—C63 | 111.5 (4) |
N23—C4—N21 | 5 (3) | N23—C53—C73 | 109.9 (5) |
N22—C4—C11 | 116.7 (14) | C63—C53—C73 | 110.9 (5) |
O1—C4—C11 | 120.7 (4) | N23—C53—H53 | 108.1 |
N23—C4—C11 | 110 (2) | C63—C53—H53 | 108.1 |
N21—C4—C11 | 113.5 (10) | C73—C53—H53 | 108.1 |
C4—N21—C51 | 121.4 (18) | O23—C63—C53 | 111.9 (4) |
C4—N21—H4 | 119.3 | O23—C63—H63A | 109.2 |
C51—N21—H4 | 119.3 | C53—C63—H63A | 109.2 |
N21—C51—C61 | 111.5 (4) | O23—C63—H63B | 109.2 |
N21—C51—C71 | 109.8 (4) | C53—C63—H63B | 109.2 |
C61—C51—C71 | 110.8 (5) | H63A—C63—H63B | 107.9 |
N21—C51—H51 | 108.2 | C63—O23—H23 | 109.5 |
C61—C51—H51 | 108.2 | O33—C73—O43 | 123.2 (7) |
C71—C51—H51 | 108.2 | O33—C73—C53 | 120.0 (6) |
O21—C61—C51 | 112.1 (4) | O43—C73—C53 | 116.8 (6) |
N1—C11—C4—N21 | 170.3 (8) | C61—C51—C71—O41 | 48.4 (19) |
C11—C4—N21—C51 | 174.1 (7) | O1—C4—N22—C52 | 1 (2) |
C4—N21—C51—C71 | −113.0 (12) | N23—C4—N22—C52 | 142 (19) |
N21—C51—C71—O31 | 102.4 (15) | N21—C4—N22—C52 | 165 (27) |
N1—C11—C21—C31 | −76.8 (10) | C11—C4—N22—C52 | 179.4 (12) |
N1—C12—C22—C32 | 87.9 (9) | C4—N22—C52—C62 | 110 (2) |
N21—C51—C61—O21 | −63.7 (11) | C4—N22—C52—C72 | −125 (2) |
N22—C52—C62—O22 | 45.3 (13) | C72—C52—C62—O22 | −78.6 (12) |
N23—C53—C63—O23 | 170 (3) | N22—C52—C72—O32 | 101 (3) |
C4—C11—C21—C31 | 161.3 (7) | C62—C52—C72—O32 | −134 (3) |
N1—C11—C4—N22 | 169.4 (12) | N22—C52—C72—O42 | −74 (2) |
C21—C11—C4—N22 | −64.0 (14) | C62—C52—C72—O42 | 51 (2) |
N1—C11—C4—O1 | −12.2 (6) | N22—C4—N23—C53 | −28 (16) |
C21—C11—C4—O1 | 114.5 (7) | O1—C4—N23—C53 | 15 (4) |
N1—C11—C4—N23 | 174.7 (19) | N21—C4—N23—C53 | −43 (28) |
C21—C11—C4—N23 | −59 (2) | C11—C4—N23—C53 | −172.9 (18) |
C21—C11—C4—N21 | −63.1 (10) | C4—N23—C53—C63 | 118 (3) |
N22—C4—N21—C51 | −20 (25) | C4—N23—C53—C73 | −119 (3) |
O1—C4—N21—C51 | −3.3 (15) | C73—C53—C63—O23 | 47 (3) |
N23—C4—N21—C51 | 123 (30) | N23—C53—C73—O33 | 96 (4) |
C4—N21—C51—C61 | 123.8 (10) | C63—C53—C73—O33 | −140 (4) |
C71—C51—C61—O21 | 173.7 (10) | N23—C53—C73—O43 | −84 (5) |
C61—C51—C71—O31 | −134.1 (15) | C63—C53—C73—O43 | 40 (5) |
N21—C51—C71—O41 | −75 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O31i | 0.91 | 1.99 | 2.862 (15) | 160 |
N1—H2···O41ii | 0.91 | 1.98 | 2.84 (2) | 157 |
N1—H3···O41iii | 0.91 | 1.98 | 2.86 (2) | 163 |
C11—H111···O1iv | 1.00 | 2.35 | 3.238 (6) | 147 |
N21—H4···O31iv | 0.88 | 1.95 | 2.82 (3) | 173 |
O21—H21···O21v | 0.84 | 2.29 | 3.081 (6) | 158 |
O22—H22···O31iv | 0.84 | 2.61 | 3.37 (2) | 152 |
O23—H23···O21vi | 0.84 | 2.17 | 2.77 (2) | 129 |
Symmetry codes: (i) −y+1, x, z+1; (ii) −y+1, x, z; (iii) y+1/2, −x+3/2, z+1/2; (iv) x, y, z+1; (v) y+1/2, −x+3/2, z−1/2; (vi) −y+3/2, x−1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C7H14N2O4 |
Mr | 190.20 |
Crystal system, space group | Tetragonal, I4 |
Temperature (K) | 105 |
a, c (Å) | 18.335 (7), 5.141 (2) |
V (Å3) | 1728.1 (12) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.39 × 0.09 × 0.06 |
Data collection | |
Diffractometer | Bruker APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.788, 0.993 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6072, 862, 780 |
Rint | 0.084 |
(sin θ/λ)max (Å−1) | 0.597 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.080, 0.195, 1.30 |
No. of reflections | 862 |
No. of parameters | 177 |
No. of restraints | 767 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.38, −0.30 |
Computer programs: APEX2 (Bruker, 2007), SAINT-Plus (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
N1—C11—C4—N21 | 170.3 (8) | N1—C12—C22—C32 | 87.9 (9) |
C11—C4—N21—C51 | 174.1 (7) | N21—C51—C61—O21 | −63.7 (11) |
C4—N21—C51—C71 | −113.0 (12) | N22—C52—C62—O22 | 45.3 (13) |
N21—C51—C71—O31 | 102.4 (15) | N23—C53—C63—O23 | 170 (3) |
N1—C11—C21—C31 | −76.8 (10) |
Parameter | Ala–Ala* | Abu–Ala** | (I) |
a, b (Å) | 17.985 (5) | 17.9290 (12) | 18.355 (7) |
c (Å) | 5.154 (3) | 5.2196 (5) | 5.141 (2) |
V (Å3) | 1667.1 | 1677.8 (2) | 1728.1 (12) |
Dx (Mg m-3) | 1.276 | 1.379 | 1.462 |
Notes: (*) Fletterick et al. (1970); (**) Görbitz (2002). |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O31i | 0.91 | 1.99 | 2.862 (15) | 160.3 |
N1—H2···O41ii | 0.91 | 1.98 | 2.84 (2) | 156.9 |
N1—H3···O41iii | 0.91 | 1.98 | 2.86 (2) | 163.1 |
C11—H111···O1iv | 1.00 | 2.35 | 3.238 (6) | 147.1 |
N21—H4···O31iv | 0.88 | 1.95 | 2.82 (3) | 173.3 |
O21—H21···O21v | 0.84 | 2.29 | 3.081 (6) | 157.5 |
O22—H22···O31iv | 0.84 | 2.61 | 3.37 (2) | 152.1 |
O23—H23···O21vi | 0.84 | 2.17 | 2.77 (2) | 129.3 |
Symmetry codes: (i) −y+1, x, z+1; (ii) −y+1, x, z; (iii) y+1/2, −x+3/2, z+1/2; (iv) x, y, z+1; (v) y+1/2, −x+3/2, z−1/2; (vi) −y+3/2, x−1/2, z−1/2. |