L Phenyl­alanine–nitric acid (2/1)

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organic papers

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N. Srinivasanet al. 2C9H11NO2H+NO3ÿ DOI: 10.1107/S1600536801014350 Acta Cryst.(2001). E57, o916±o918

Acta Crystallographica Section E

Structure Reports

Online

ISSN 1600-5368

L

-Phenylalanine±nitric acid (2/1)

N. Srinivasan,aB. Sridharb and

R. K. Rajaramb*

aDepartment of Physics, Thiagarajar College,

Madurai 625 009, India, andbDepartment of

Physics, Madurai Kamaraj University, Madurai 625 021, India

Correspondence e-mail: sshiya@yahoo.com

Key indicators

Single-crystal X-ray study

T= 293 K

Mean(C±C) = 0.012 AÊ H-atom completeness 70%

Rfactor = 0.069

wRfactor = 0.220 Data-to-parameter ratio = 7.6

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2001 International Union of Crystallography Printed in Great Britain ± all rights reserved

In the title compound, 2 C9H11NO2H+NO3ÿ, both

phenyl-alanine residues have agaucheI conformation. The aggrega-tion of the hydrophilic zone is alongz= 0 and the hydrophobic zone is sandwiched between two such layers atz= 0 andz= 1.

Comment

The crystal structures of l-phenylalanine hydrochloride (Gurskaya & Vainshtein, 1963; Al-Karaghouli & Koetzle, 1975),l-phenylalaninel-phenylalaninium formate (Gorbitz & Etter, 1992), bis(l-phenylalanine) sulfate monohydrate (Nagashima et al., 1992) and l-phenylalanine l -phenyl-alaninium perchlorate (Srinivasan & Rajaram, 1997) have been reported. Even though the title compound, (I), has been studied (Srikrishnan et al., 1984), no structural data are available as the above publication does not contain the atomic coordinates and has a misprint in one of the cell dimensions. Therefore, in the present work, an independent X-ray diffraction study of the title compound was undertaken.

Both phenylalanine residues (1 and 2) have similar geometries (Fig. 1). In both residues, the bond distances CÐO [1.313 (6) and 1.311 (7) AÊ] and C O [1.202 (8) and 1.220 (7) AÊ] are nearly equal and the single-bonded O atoms of 1 and 2 (O12 O22) are at a distance of 2.426 (8) AÊ. This may refer to a short hydrogen bond between the singly bonded carboxyl O atoms (O12 O22), as found in l -phenylalanine l-phenylalaninium perchlorate (Srinivasan & Rajaram, 1997). However, this H atom could not be located unequivocally. Hence, taking into account the equality of the CÐO distances (see above), it can be surmised that the two residues may be connected by either a symmetric hydrogen bond or an asymmetric hydrogen bond with the H atom disordered over two positions.

The conformation angles 1 for residues 1 and 2 are ÿ9.9 (7) and 2.5 (8), respectively (see Table 1). This tendency

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towards non-planarity is also found in various amino acids (Lakshminarayanan et al., 1967). The branched side confor-mation angle 1 shows a gauche I conformation for both

residues [68.2 (7) and 71.0 (7)], which agrees well with formate and perchlorate complexes. The 21 [89.0 (8) and

97.0 (8)] and 22 [ÿ92.3 (8) and ÿ84.3 (7)] torsion angles indicate that the residues have folded conformations.

The aggregation of the hydrophilic zone is along thez= 0 plane. The hydrophobic zone atz =1

2consists of the phenyl

groups of both molecules and is sandwiched between two hydrophilic layers in the planes z= 0 andz= 1 (Fig. 2).

Experimental

The title compound was crystallized from an aqueous solution of a 2:1 stoichiometric ratio of l-phenylalanine and nitric acid by slow evaporation.

Crystal data 2C9H11NO2H+NO3ÿ

Mr= 393.39

Monoclinic,P21

a= 12.536 (16) AÊ b= 5.378 (4) AÊ c= 14.962 (9) AÊ = 107.83 (8)

V= 960.2 (15) AÊ3

Z= 2

Dx= 1.361 Mg mÿ3

Dm= 1.350 Mg mÿ3

Dmmeasured by ¯otation in a

mixture of carbon tetrachloride and xylene

MoKradiation Cell parameters from 25

re¯ections = 14.5±23.4 = 0.11 mmÿ1

T= 293 (2) K Needle, colorless 0.450.300.15 mm Data collection

Enraf±Nonius CAD-4 diffractometer !±2scans

Absorption correction: scan (Northet al., 1968) Tmin= 0.963,Tmax= 0.984

1895 measured re¯ections 1895 independent re¯ections

1356 re¯ections withI> 2(I) max= 25.0

h=ÿ14!14 k= 0!6 l= 0!17

3 standard re¯ections frequency: 60 min intensity decay: none Re®nement

Re®nement onF2

R[F2> 2(F2)] = 0.069

wR(F2) = 0.220

S= 1.09 1895 re¯ections 250 parameters

H-atom parameters constrained

w= 1/[2(F

o2) + (0.1548P)2]

whereP= (Fo2+ 2Fc2)/3

(/)max< 0.001

max= 0.30 e AÊÿ3

min=ÿ0.34 e AÊÿ3

Absolute structure: Flack (1983) Flack parameter = 0 (4)

Table 1

Selected geometric parameters (AÊ,).

O11ÐC11 1.202 (8)

O12ÐC11 1.313 (6) O21ÐC21O22ÐC21 1.220 (7)1.311 (7)

O11ÐC11ÐC12ÐN11 ÿ9.9 (7) N11ÐC12ÐC13ÐC14 68.2 (7) C12ÐC13ÐC14ÐC19 89.0 (8) C12ÐC13ÐC14ÐC15 ÿ92.3 (8)

O21ÐC21ÐC22ÐN21 2.5 (8) N21ÐC22ÐC23ÐC24 71.0 (7) C22ÐC23ÐC24ÐC29 97.0 (8) C22ÐC23ÐC24ÐC25 ÿ84.3 (7)

H atoms bonded to C atoms were placed in geometrically calcu-lated positions and allowed to ride on the attached atoms. Attempts to introduce H atoms attached to the amino N atom yielded a slight increase in all discrepancy values. Therefore, these H atoms were not included in the ®nal re®nement. The absolute con®guration is known from the synthesis and is indeterminate from the X-ray diffraction experiment.

Data collection: CAD-4 Software (Enraf±Nonius, 1989); cell re®nement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne structure:SHELXL97 (Sheldrick, 1997); molecular graphics:PLATON(Spek, 1999); software used to prepare material for publication:SHELXL97.

BS and RKR thank the Department of Science and Tech-nology (DST), Government of India, for ®nancial support.

References

Al-Karaghouli, A. R. & Koetzle, T. F. (1975).Acta Cryst.B31, 2461±2465. Enraf±Nonius (1989).CAD-4Software. Version 5.0. Enraf±Nonius, Delft, The

Netherlands.

Flack H. D. (1983).Acta Cryst.A39, 876±881.

Acta Cryst.(2001). E57, o916±o918 N. Srinivasanet al. 2C9H11NO2H+NO3ÿ

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organic papers

Figure 1

The structures of phenylalanine residues showing the atomic numbering scheme and 50% probability displacement ellipsoids (Johnson, 1976).

Figure 2

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organic papers

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N. Srinivasanet al. 2C9H11NO2H+NO3ÿ Acta Cryst.(2001). E57, o916±o918

Gorbitz, C. H. & Etter, M. C. (1992).Acta Cryst.C48, 1317±1320.

Gurskaya, G. V. & Vainshtein, B. K. (1963).Sov. Phys. Crystallogr.8, 288±291. Johnson, C. K. (1976).ORTEPII. Report ORNL-5138. Oak Ridge National

Laboratory, Tennessee, USA.

Lakshminarayanan, A. V., Sashisekaran, V. & Ramachandran, G. N. (1967). In Conformation of Biopolymers, edited by G. N. Ramachandran. London: Academic Press.

Nagashima, N., Sano, C., Kawakita, T. & Iitaka, Y. (1992).Anal. Sci.8, 723± 725.

North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968).Acta Cryst.A24, 351± 359.

Sheldrick, G. M. (1997). SHELXL97 and SHELXS97. University of GoÈttingen, Germany.

Spek, A. L. (1999). PLATON for Windows. Utrecht University, The Netherlands.

Srikrishnan, T., Narasinga Rao, S. & Parthasarathy, R. (1984).Acta Cryst.A40, C-92.

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Acta Cryst. (2001). E57, o916–o918

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Acta Cryst. (2001). E57, o916–o918 [doi:10.1107/S1600536801014350]

L

-Phenylalanine

nitric acid (2/1)

N. Srinivasan, B. Sridhar and R. K. Rajaram

S1. Comment

The crystal structures of L-phenylalanine hydrochloride (Gurskaya & Vainstein, 1963; Al-Karaghouli & Koetzle, 1975),

L-phenylalanine L-phenylalaninium formate (Gorbitz & Etter, 1992), bis(L-phenylalanine) sulfate monohydrate

(Nagashima et al., 1992) and L-phenylalanine L-phenylalaninium perchlorate (Srinivasan & Rajaram, 1997) have been

reported. Even though the title compound, (I), has been studied (Srikrishnan et al., 1984), no structural data are available

as the above publication does not contain the atomic coordinates and has a misprint in one of the cell dimensions.

Therefore, in the present work, an independent X-ray diffraction study of the title compound was undertaken.

Both phenylalanine residues (1 and 2) have similar geometries (Fig. 1). In both residues, the bond distances C—O

[1.313 (6) and 1.311 (7) Å] and C═O [1.202 (8) and 1.220 (7) Å] are nearly equal and the single-bonded O atoms of 1

and 2 (O12···O22) are at a distance of 2.426 (8) Å. This may refer to a short hydrogen bond between the singly bonded

carboxyl O atoms (O12···O22), as found in L-phenylalanine L-phenylalaninium perchlorate (Srinivasan & Rajaram,

1997). However, this H atom could not be located objectively. Hence, taking into account the equality of the C—O

distances (see above), it can be surmised that the two residues may be connected by either a symmetric hydrogen bond or

an asymmetric hydrogen bond with the H atom disordered over two positions.

The conformation angles ψ1 for residues 1 and 2 are -9.9 (7) and 2.5 (8)°, respectively (see Table 1). This tendency

towards non-planarity is also found in various amino acids (Lakshminarayanan et al., 1967). The branched side

conformation angle χ1 shows a gauche I conformation for both residues [68.2 (7) and 71.0 (7)°], which agrees well with

formate and perchlorate complexes. The χ21 [89.0 (8) and 97.0 (8)°] and χ22 [92.3 (8) and -84.3 (7)°] torsion angles

indicate that the residues have folded conformation.

The aggregation of hydrophilic zone is along z = 0 plane. The hydrophobic zone at z = 1/2 consists of the phenyl groups

of both molecules and is sandwiched between two hydrophilic layers at z = 0 and z = 1 planes (Fig. 2).

S2. Experimental

The title compound was crystallized from an aqueous solution of a 2:1 stoichiometric ratio of L-phenylalanine and nitric

acid by slow evaporation.

S3. Refinement

H atoms bonded to C atoms were placed in geometrically calculated positions and allowed to ride on the attached atom.

Attempts to introduce H atoms attached to the amino N atom yielded a slight increase in all discrepancy values.

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Acta Cryst. (2001). E57, o916–o918 Figure 1

The structures of phenylalanine residues showing the atomic numbering scheme and 50% probability displacement

ellipsoids (Johnson, 1976).

Figure 2

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Acta Cryst. (2001). E57, o916–o918

L-Phenylalanine–nitric acid (2/1)

Crystal data

2C9H11NO2·H+·NO3−

Mr = 393.39

Monoclinic, P21

a = 12.536 (16) Å

b = 5.378 (4) Å

c = 14.962 (9) Å

β = 107.83 (8)°

V = 960.2 (15) Å3

Z = 2

F(000) = 416

Dx = 1.361 Mg m−3

Dm = 1.350 Mg m−3

Dm measured by flotation in a mixture of carbon tetrachloride and xylene

Mo radiation, λ = 0.71073 Å Cell parameters from 25 reflections

θ = 14.5–23.4°

µ = 0.11 mm−1

T = 293 K Needle, colorless 0.45 × 0.3 × 0.15 mm

Data collection

Enraf-Nonius sealed tube diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

ω–2θ scans

Absorption correction: ψ scan (North et al., 1968)

Tmin = 0.963, Tmax = 0.984 1895 measured reflections

1895 independent reflections 1356 reflections with I > 2σ(I)

Rint = 0.000

θmax = 25.0°, θmin = 2.5°

h = −14→14

k = 0→6

l = 0→17

3 standard reflections every 60 min intensity decay: none

Refinement

Refinement on F2 Least-squares matrix: full

R[F2 > 2σ(F2)] = 0.069

wR(F2) = 0.220

S = 1.09 1895 reflections 250 parameters 3 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

Hydrogen site location: inferred from neighbouring sites

H-atom parameters constrained

w = 1/[σ2(F

o2) + (0.1548P)2] where P = (Fo2 + 2Fc2)/3 (Δ/σ)max < 0.001

Δρmax = 0.30 e Å−3 Δρmin = −0.34 e Å−3

Absolute structure: Flack H D (1983) Absolute structure parameter: 0 (4)

Special details

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.

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Acta Cryst. (2001). E57, o916–o918

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

x y z Uiso*/Ueq

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Acta Cryst. (2001). E57, o916–o918 Atomic displacement parameters (Å2)

U11 U22 U33 U12 U13 U23

N 0.041 (2) 0.050 (4) 0.059 (4) −0.010 (3) 0.012 (2) 0.006 (4) O1 0.080 (4) 0.064 (5) 0.177 (9) −0.014 (4) 0.036 (5) −0.011 (6) O2 0.093 (5) 0.070 (5) 0.223 (11) 0.037 (5) 0.072 (6) 0.003 (6) O3 0.042 (2) 0.066 (4) 0.094 (4) −0.004 (3) 0.013 (2) 0.004 (4) O11 0.048 (2) 0.031 (2) 0.042 (3) −0.009 (2) −0.0024 (18) −0.002 (2) O12 0.0278 (16) 0.050 (3) 0.098 (4) 0.002 (2) 0.020 (2) −0.019 (3) C11 0.029 (2) 0.039 (4) 0.029 (3) 0.016 (3) 0.004 (2) −0.005 (3) C12 0.040 (3) 0.034 (4) 0.037 (3) 0.001 (3) 0.017 (2) 0.003 (3) N11 0.040 (2) 0.033 (3) 0.054 (3) 0.002 (3) 0.025 (2) −0.004 (3) C13 0.055 (3) 0.028 (4) 0.052 (4) 0.003 (3) 0.020 (3) −0.011 (3) C14 0.053 (3) 0.042 (4) 0.043 (4) −0.011 (3) 0.021 (3) −0.002 (4) C15 0.051 (3) 0.058 (5) 0.060 (4) −0.002 (4) 0.022 (3) −0.005 (4) C16 0.090 (6) 0.130 (11) 0.060 (5) −0.029 (7) 0.043 (5) 0.006 (7) C17 0.123 (8) 0.087 (8) 0.052 (5) −0.033 (7) 0.033 (5) 0.003 (6) C18 0.117 (7) 0.052 (5) 0.057 (5) −0.027 (6) −0.008 (5) 0.024 (5) C19 0.076 (4) 0.046 (4) 0.022 (3) 0.005 (4) −0.005 (3) 0.000 (3) O21 0.048 (2) 0.035 (2) 0.041 (2) 0.006 (2) 0.0207 (19) 0.000 (2) O22 0.056 (2) 0.036 (3) 0.087 (4) 0.001 (2) 0.040 (3) 0.004 (3) C21 0.032 (2) 0.027 (3) 0.047 (4) −0.011 (3) 0.018 (2) −0.009 (3) C22 0.036 (2) 0.028 (3) 0.037 (3) 0.002 (3) 0.005 (2) −0.010 (3) N21 0.036 (2) 0.051 (3) 0.044 (3) 0.014 (3) 0.012 (2) −0.003 (3) C23 0.053 (3) 0.040 (4) 0.051 (4) 0.001 (3) 0.016 (3) 0.015 (4) C24 0.040 (3) 0.036 (4) 0.041 (4) 0.003 (3) −0.005 (3) 0.010 (3) C25 0.046 (3) 0.066 (5) 0.037 (4) −0.004 (4) 0.013 (3) −0.006 (4) C26 0.066 (5) 0.083 (8) 0.099 (8) −0.004 (6) −0.001 (5) −0.018 (7) C27 0.091 (5) 0.057 (5) 0.041 (4) −0.022 (5) 0.013 (4) −0.018 (4) C28 0.083 (5) 0.061 (6) 0.040 (4) 0.012 (5) 0.010 (4) −0.010 (4) C29 0.071 (4) 0.055 (5) 0.045 (4) 0.013 (4) 0.025 (4) −0.004 (4)

Geometric parameters (Å, º)

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C15—C16 1.382 (13) C26—C27 1.408 (10) C15—H15 0.9300 C26—H26 0.9300 C16—C17 1.307 (16) C27—C28 1.332 (11) C16—H16 0.9300 C27—H27 0.9300 C17—C18 1.421 (14) C28—C29 1.344 (12) C17—H17 0.9300 C28—H28 0.9300 C18—C19 1.400 (12) C29—H29 0.9300 C18—H18 0.9300

O2—N—O1 129.1 (6) C18—C19—H19 120.3 O2—N—O3 117.4 (7) O21—C21—O22 123.7 (6) O1—N—O3 113.5 (7) O21—C21—C22 123.6 (5) O11—C11—O12 127.0 (6) O22—C21—C22 112.6 (5) O11—C11—C12 122.9 (5) C21—C22—C23 114.7 (5) O12—C11—C12 109.8 (6) C21—C22—N21 106.4 (5) N11—C12—C13 111.2 (5) C23—C22—N21 111.5 (4) N11—C12—C11 106.8 (5) C21—C22—H22 108.0 C13—C12—C11 113.5 (5) C23—C22—H22 108.0 N11—C12—H12 108.4 N21—C22—H22 108.0 C13—C12—H12 108.4 C24—C23—C22 113.4 (6) C11—C12—H12 108.4 C24—C23—H23A 108.9 C14—C13—C12 116.3 (6) C22—C23—H23A 108.9 C14—C13—H13A 108.2 C24—C23—H23B 108.9 C12—C13—H13A 108.2 C22—C23—H23B 108.9 C14—C13—H13B 108.2 H23A—C23—H23B 107.7 C12—C13—H13B 108.2 C29—C24—C25 115.1 (7) H13A—C13—H13B 107.4 C29—C24—C23 123.0 (6) C19—C14—C15 118.8 (7) C25—C24—C23 122.0 (6) C19—C14—C13 122.4 (6) C26—C25—C24 120.2 (4) C15—C14—C13 118.9 (7) C26—C25—H25 119.9 C16—C15—C14 117.6 (9) C24—C25—H25 119.9 C16—C15—H15 121.2 C25—C26—C27 123.1 (4) C14—C15—H15 121.2 C25—C26—H26 118.4 C17—C16—C15 126.7 (9) C27—C26—H26 118.4 C17—C16—H16 116.7 C28—C27—C26 115.4 (7) C15—C16—H16 116.7 C28—C27—H27 122.3 C16—C17—C18 115.8 (9) C26—C27—H27 122.3 C16—C17—H17 122.1 C27—C28—C29 122.9 (8) C18—C17—H17 122.1 C27—C28—H28 118.6 C19—C18—C17 121.7 (10) C29—C28—H28 118.6 C19—C18—H18 119.1 C28—C29—C24 123.2 (7) C17—C18—H18 119.1 C28—C29—H29 118.4 C14—C19—C18 119.5 (8) C24—C29—H29 118.4 C14—C19—H19 120.3

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Figure

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References

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