organic papers
o860
Carl Henrik GoÈrbitzet al. C5H9NO3 DOI: 10.1107/S1600536804009353 Acta Cryst.(2004). E60, o860±o862Acta Crystallographica Section E
Structure Reports Online
ISSN 1600-5368
N
-Acetyl-
L-alanine
Carl Henrik GoÈrbitza* and
Einar Sagstuenb
aDepartment of Chemistry, University of Oslo,
PO Box 1033 Blindern, N-0315 Oslo, Norway, andbDepartment of Physics, University of Oslo,
PO Box 1048 Blindern, N-0316 Oslo, Norway
Correspondence e-mail: [email protected]
Key indicators Single-crystal X-ray study
T= 105 K
Mean(C±C) = 0.001 AÊ
Rfactor = 0.037
wRfactor = 0.100
Data-to-parameter ratio = 28.6
For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.
#2004 International Union of Crystallography Printed in Great Britain ± all rights reserved
The crystal structure of the title compound, C5H9NO3, has
been investigated as part of a search for suitable materials for electron paramagnetic resonance (EPR) radiation dosimetry.
Comment
The simple amino acid alanine has, during the last 15 years, been developed to be the standard material for radiation dosimetry using electron paramagnetic resonance (EPR) spectrometry as the readout technique (Regulla & Deffner, 1982). EPR/alanine dosimetry is simple, versatile, repro-ducible and non-destructible upon dose readout. The disad-vantage is the sensitivity; alanine is, for all practical purposes, usable only for doses above 1 Gy and is thus not well suited for clinical work. A search for more suitable materials for EPR dosimetry has been pursued in several laboratories over recent years (Vestadet al., 2003; Lundet al., 2004).N -Acetyl-l-alanine, (I), is one such possible material. However, to learn the dosimetric properties of this compound and to understand the prospects of enhancing the sensitivity, there is a need to characterize the physical properties of radiation-induced radicals in crystalline (I) using EPR spectroscopy. Accord-ingly, knowledge of the crystal structure of (I) is necessary.
The molecular structure of (I) is illustrated in Fig. 1. Bond lengths and angles are normal. Crystal structures are available (Cambridge Structural Database, Version 5.25 of November 2003; Allen, 2002) for seven otherN-acetyl derivatives of the 20 commonl-amino acids:N-acetylglycine (Mackay, 1975),N -acetyl-l-phenylalanine (Stoutet al., 2000),N-acetyl-l-cysteine (Takusagawaet al., 1981),N-acetyl-l-glutamine (Narasimha-murthyet al., 1976),N-acetyl-l-tyrosine (Koszelak & van der Helm, 1981),N-acetyl-l-tryptophan (Yamaneet al., 1977) and
N-acetyl-l-glutamic acid (Dobson & Gerkin, 1997). The
structures ofN-acetyl-l-norvaline (Lovaset al., 1974) and the racemates N-acetyl-dl-methionine (Ponnuswamy & Trotter, 1985) andN-acetyl-dl-valine (Carrollet al., 1990) are relevant additions to this group. A typical feature for these compounds
(and indeed for N-acyl amino acids in general; Chen &
Parthasarathy, 1977) is the presence of ÐCOOH
O C(amide) and >NÐH O C(carboxyl) hydrogen
bonds. The former is missing only forN-acetyl-dl-valine, the
latter only forN-acetyl-l-cysteine. Compound (I) thus shares its two most important intermolecular interactions (Table 2)
with almost all other N-acetyl amino acids, and even has
essentially the same folded molecular conformation [C1Ð
C2ÐN1ÐC4 = ÿ70.77 (7); Table 1] as N-acetyl-l
-phenyl-alanine, N-acetyl-l-tyrosine, N-acetyl-l-norvaline and the l
-enantiomer in N-acetyl-dl-methionine. Nevertheless, the
speci®c hydrogen-bond pattern of (I) is not found for any of the compounds listed above. A very similar structure with the same overall crystal packing pattern has, however, been observed forN-acetyl-(S)-isovaline, (II) (Crismaet al., 1998). The only difference between the two pertains to the weak
C2ÐH21 O3 hydrogen bonds of (I) (Table 2), which are
broken in (II) as the separation of hydrogen-bonded zigzag
layers of peptide molecules is increased to make room for the two extra methyl groups (Fig. 2). In the process, the length of the longest axis is increased from 11.5449 (3) AÊ for (I) to 14.577 (2) AÊ for (II).
Experimental
N-Acetyl-l-alanine was obtained from Sigma±Aldrich. Crystals were prepared by recrystallization from a methanol solution at room temperature.
Crystal data
C5H9NO3
Mr= 131.13
Orthorhombic,P21212
a= 10.3879 (2) AÊ
b= 11.5449 (3) AÊ
c= 5.74260 (10) AÊ
V= 688.69 (3) AÊ3
Z= 4
Dx= 1.265 Mg mÿ3
MoKradiation
Cell parameters from 10 042 re¯ections
= 2.6±44.8
= 0.11 mmÿ1
T= 105 (2) K Plate, colourless 1.151.000.03 mm
Data collection
Bruker SMART CCD diffractometer
!scans
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)
Tmin= 0.688,Tmax= 0.997 14 223 measured re¯ections
3149 independent re¯ections 2839 re¯ections withI> 2(I)
Rint= 0.018
max= 44.8
h=ÿ19!20
k=ÿ22!22
l=ÿ11!10
Re®nement
Re®nement onF2
R[F2> 2(F2)] = 0.037
wR(F2) = 0.100
S= 1.12 3149 re¯ections 110 parameters
Only coordinates of H atoms re®ned
w= 1/[2(F
o2) + (0.0667P)2
+ 0.0041P]
whereP= (Fo2+ 2Fc2)/3
(/)max= 0.004
max= 0.48 e AÊÿ3
min=ÿ0.20 e AÊÿ3
Table 1
Selected torsion angles ().
O1ÐC1ÐC2ÐN1 149.71 (7)
C1ÐC2ÐN1ÐC4 ÿ70.77 (7) C2ÐN1ÐC4ÐO3 ÿ1.92 (9)
Table 2
Hydrogen-bonding geometry (AÊ,).
DÐH A DÐH H A D A DÐH A
N1ÐH1 O1i 0.783 (15) 2.190 (15) 2.9586 (8) 167.0 (12) O2ÐH2 O3ii 0.83 (2) 1.793 (19) 2.5831 (7) 158 (2) C2ÐH21 O3iii 0.995 (14) 2.624 (13) 3.3211 (8) 127.1 (11) C5ÐH53 O3i 0.903 (18) 2.65 (2) 3.3641 (9) 136.8 (13)
Symmetry codes: (i)x;y;zÿ1; (ii)1
2x;12ÿy;1ÿz; (iii) 1ÿx;ÿy;z.
Positional parameters were re®ned for all H atoms. Uisovalues
were 1.2Ueq (methylene and amide) or 1.5Ueq (carboxylate and
methyl) of the carrier atom.
Data collection:SMART(Bruker, 1998); cell re®nement: SAINT-Plus(Bruker, 2001); data reduction:SAINT-Plus; program(s) used to solve structure:SHELXTL(Bruker, 2000); program(s) used to re®ne structure:SHELXTL; molecular graphics:SHELXTL; software used to prepare material for publication:SHELXTL.
Acta Cryst.(2004). E60, o860±o862 Carl Henrik GoÈrbitzet al. C5H9NO3
o861
organic papers
Figure 2
The molecular packing and unit cell viewed along thecaxis. Spheres show the positions of O3 atoms in neighbouring molecules, included here to illustrate the hydrogen-bond network. Hydrogen bonds with NÐH and OÐH donors are shown as dashed black lines and the C2ÐH21 O3 hydrogen bonds are shown as dashed orange lines (the C5ÐH53 O3 interaction runs parallel to the viewing direction and is not visible).
Figure 1
organic papers
o862
Carl Henrik GoÈrbitzet al. C5H9NO3 Acta Cryst.(2004). E60, o860±o862The purchase of the Bruker SMART CCD diffractometer was made possible through support from the Research Council of Norway (NFR).
References
Allen, F. H. (2002).Acta Cryst.B58, 380±388.
Bruker (1998).SMART. Version 5.054. Bruker AXS Inc., Madison, Wisconsin, USA.
Bruker (2000). SHELXTL. Version 6.10. Bruker AXS Inc., Madison, Wisconsin, USA.
Bruker (2001). SAINT-Plus. Version 6.22. Bruker AXS Inc., Madison, Wisconsin, USA.
Carroll, P. J., Stewart, P. L. & Opella, S. J. (1990).Acta Cryst.C46, 243±246. Chen, C. & Parthasarathy, R. (1977).Int. J. Pept. Protein Res.11, 9±18. Crisma, M., Valle, G., Formaggio, F., Toniolo, C., Broxterman, Q. B. &
Kamphuis, J. (1998).Z. Kristallogr. New Cryst. Struct.213, 313.
Dobson, A. J. & Gerkin, R. E. (1997).Acta Cryst.C53, 73±76.
Koszelak, S. N. & van der Helm, D. (1981). Acta Cryst. B37, 1122± 1124.
Lovas, G., Kalman, A. & Argay, G. (1974).Acta Cryst.B30, 2882±2883. Lund, E., Gustafsson, H., Danilczuk, M., Sastry, M. D., Lund, A., Vestad, T. A.,
Malinen, E., Hole, E. O. & Sagstuen, E. (2004).Appl. Radiat. Isot.61. In the press.
Mackay, M. F. (1975).Cryst. Struct. Commun.4, 225±228.
Narasimhamurthy, M. R., Venkatesan, K. & Winkler, F. (1976).J. Chem. Soc. Perkin Trans.2, pp. 768±771.
Ponnuswamy, M. N. & Trotter, J. (1985).Acta Cryst.C41, 917±919. Regulla, D. F. & Deffner, U. (1982).Appl. Radiat. Isot.33, 1101±1114. Sheldrick, G. M. (1996).SADABS. University of GoÈttingen, Germany. Stout, K. L., Hallock, K. J., Kampf, J. W. & Ramamoorthy, A. (2000).Acta
Cryst.C56, e100.
Takusagawa, F., Koetzle, T. F., Kou, W. W. H. & Parthasarathy, R. (1981).Acta Cryst.B37, 1591±1596.
Vestad, T. A., Malinen, E., Lund, A., Hole, E. O. & Sagstuen, E. (2003).Appl. Radiat. Isot.59, 181±188.
supporting information
sup-1
Acta Cryst. (2004). E60, o860–o862
supporting information
Acta Cryst. (2004). E60, o860–o862 [https://doi.org/10.1107/S1600536804009353]
N
-Acetyl-
L-alanine
Carl Henrik G
ö
rbitz and Einar Sagstuen
N-acetyl-L-alanine
Crystal data
C5H9NO3
Mr = 131.13
Orthorhombic, P21212
a = 10.3879 (2) Å b = 11.5449 (3) Å c = 5.7426 (1) Å V = 688.69 (3) Å3
Z = 4 F(000) = 280
Dx = 1.265 Mg m−3
Mo Kα radiation, λ = 0.71073 Å Cell parameters from 10042 reflections θ = 2.6–44.8°
µ = 0.11 mm−1
T = 105 K Rod, colourless 1.15 × 1.00 × 0.03 mm
Data collection
Siemens SMART CCD diffractometer
Radiation source: fine-focus sealed tube Graphite monochromator
Detector resolution: 8.3 pixels mm-1
sets of exposures each taken over 0.3° ω rotation scans
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)
Tmin = 0.688, Tmax = 0.997
14223 measured reflections 3149 independent reflections 2839 reflections with I > 2σ(I) Rint = 0.018
θmax = 44.8°, θmin = 2.6°
h = −19→20 k = −22→22 l = −11→10
Refinement
Refinement on F2
Least-squares matrix: full R[F2 > 2σ(F2)] = 0.037
wR(F2) = 0.100
S = 1.12 3149 reflections 110 parameters 0 restraints
Primary atom site location: structure-invariant direct methods
Secondary atom site location: difference Fourier map
Hydrogen site location: inferred from neighbouring sites
Only H-atom coordinates refined w = 1/[σ2(F
o2) + (0.0667P)2 + 0.0041P]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max = 0.004
Δρmax = 0.48 e Å−3
Δρmin = −0.20 e Å−3
Special details
supporting information
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Acta Cryst. (2004). E60, o860–o862
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
x y z Uiso*/Ueq
O1 0.81329 (7) 0.09735 (6) 0.75696 (10) 0.02963 (12)
O2 0.85613 (5) 0.18877 (5) 0.41981 (10) 0.02481 (10)
H2 0.9025 (17) 0.2286 (17) 0.506 (5) 0.059 (6)*
O3 0.51974 (5) 0.16482 (4) 0.41255 (9) 0.02180 (9)
N1 0.66665 (5) 0.07061 (5) 0.19533 (9) 0.01857 (8)
H1 0.7038 (12) 0.0665 (11) 0.077 (3) 0.022*
C1 0.80154 (5) 0.10683 (5) 0.54602 (10) 0.01860 (9)
C2 0.72609 (5) 0.01901 (5) 0.40063 (11) 0.01824 (9)
H21 0.6577 (11) −0.0100 (11) 0.507 (3) 0.022*
C3 0.81747 (7) −0.07828 (7) 0.32424 (18) 0.02913 (14)
H31 0.7701 (17) −0.1388 (15) 0.246 (4) 0.044*
H32 0.8605 (16) −0.1146 (15) 0.458 (4) 0.044*
H33 0.8800 (15) −0.0455 (15) 0.229 (4) 0.044*
C4 0.56610 (5) 0.14300 (5) 0.21649 (10) 0.01755 (8)
C5 0.51119 (8) 0.19283 (8) −0.00456 (12) 0.02748 (13)
H51 0.4989 (16) 0.2699 (14) 0.000 (4) 0.041*
H52 0.4231 (15) 0.1525 (13) −0.027 (4) 0.041*
H53 0.5587 (15) 0.1767 (15) −0.132 (3) 0.041*
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
O1 0.0314 (2) 0.0414 (3) 0.01606 (17) −0.0084 (2) 0.00052 (17) 0.00236 (18) O2 0.0284 (2) 0.0273 (2) 0.01877 (18) −0.01075 (16) −0.00013 (17) 0.00106 (16) O3 0.02385 (18) 0.02536 (19) 0.01620 (15) 0.00601 (14) 0.00286 (15) −0.00004 (15) N1 0.01745 (17) 0.02254 (19) 0.01572 (16) 0.00031 (13) 0.00221 (13) −0.00078 (15) C1 0.01676 (18) 0.0227 (2) 0.01637 (18) −0.00072 (15) 0.00194 (15) 0.00031 (16) C2 0.01624 (17) 0.01919 (19) 0.01930 (19) −0.00039 (14) 0.00133 (16) 0.00083 (16)
C3 0.0248 (3) 0.0232 (2) 0.0394 (4) 0.00538 (19) 0.0000 (3) −0.0041 (3)
C4 0.01784 (18) 0.01914 (18) 0.01566 (17) −0.00067 (14) 0.00107 (15) 0.00082 (15)
C5 0.0282 (3) 0.0358 (3) 0.0185 (2) 0.0044 (2) 0.0005 (2) 0.0073 (2)
Geometric parameters (Å, º)
O1—C1 1.2224 (8) C2—H21 0.995 (14)
O2—C1 1.3197 (8) C3—H31 0.966 (19)
O2—H2 0.83 (2) C3—H32 0.98 (2)
O3—C4 1.2501 (7) C3—H33 0.928 (18)
N1—C4 1.3433 (8) C4—C5 1.5059 (9)
N1—C2 1.4581 (8) C5—H51 0.900 (16)
N1—H1 0.783 (15) C5—H52 1.034 (16)
C1—C2 1.5296 (8) C5—H53 0.903 (18)
C2—C3 1.5346 (9)
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Acta Cryst. (2004). E60, o860–o862
C4—N1—C2 120.69 (5) H31—C3—H32 106.8 (15)
C4—N1—H1 120.0 (10) C2—C3—H33 107.5 (11)
C2—N1—H1 117.9 (10) H31—C3—H33 112.2 (17)
O1—C1—O2 124.44 (6) H32—C3—H33 108.4 (14)
O1—C1—C2 122.19 (6) O3—C4—N1 120.42 (5)
O2—C1—C2 113.30 (5) O3—C4—C5 122.43 (6)
N1—C2—C1 112.80 (5) N1—C4—C5 117.13 (5)
N1—C2—C3 109.26 (6) C4—C5—H51 113.9 (13)
C1—C2—C3 108.92 (5) C4—C5—H52 105.4 (11)
N1—C2—H21 109.4 (8) H51—C5—H52 108.8 (13)
C1—C2—H21 104.7 (8) C4—C5—H53 113.5 (11)
C3—C2—H21 111.8 (7) H51—C5—H53 107.9 (16)
C2—C3—H31 110.3 (10) H52—C5—H53 106.9 (15)
O1—C1—C2—N1 149.71 (7) O2—C1—C2—N1 −33.23 (7)
C1—C2—N1—C4 −70.77 (7) O1—C1—C2—C3 −88.80 (9)
C2—N1—C4—O3 −1.92 (9) O2—C1—C2—C3 88.26 (7)
C4—N1—C2—C3 167.94 (6) C2—N1—C4—C5 179.66 (6)
Hydrogen-bond geometry (Å, º)
D—H···A D—H H···A D···A D—H···A
N1—H1···O1i 0.783 (15) 2.190 (15) 2.9586 (8) 167.0 (12)
O2—H2···O3ii 0.83 (2) 1.793 (19) 2.5831 (7) 158 (2)
C2—H21···O3iii 0.995 (14) 2.624 (13) 3.3211 (8) 127.1 (11)
C5—H53···O3i 0.903 (18) 2.65 (2) 3.3641 (9) 136.8 (13)
