Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801000575/na6033sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801000575/na6033Isup2.hkl |
CCDC reference: 159766
Key indicators
- Single-crystal X-ray study
- T = 150 K
- Mean (C-C) = 0.010 Å
- R factor = 0.113
- wR factor = 0.269
- Data-to-parameter ratio = 7.3
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level C:
DIFMX_01 Alert C The maximum difference density is > 0.1*ZMAX*0.75 _refine_diff_density_max given = 0.618 Test value = 0.600 DIFMX_02 Alert C The minimum difference density is > 0.1*ZMAX*0.75 The relevant atom site should be identified. RFACG_01 Alert C The value of the R factor is > 0.10 R factor given 0.113 RFACR_01 Alert C The value of the weighted R factor is > 0.25 Weighted R factor given 0.269 PLAT_731 Alert C Bond Calc 1.391(13), Rep 1.390(6) .... 2.17 s.u-Ratio C7C -C8C 1.555 1.555 PLAT_731 Alert C Bond Calc 1.388(13), Rep 1.389(6) .... 2.17 s.u-Ratio C5D -C6D 1.555 1.555 PLAT_732 Alert C Angle Calc 119.8(7), Rep 119.8(3) .... 2.33 s.u-Ratio C7A -C6A -C5A 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.9(7), Rep 119.8(3) .... 2.33 s.u-Ratio C6A -C7A -C8A 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.8(7), Rep 119.9(3) .... 2.33 s.u-Ratio C7B -C6B -C5B 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.9(7), Rep 119.8(3) .... 2.33 s.u-Ratio C6B -C7B -C8B 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.6(7), Rep 119.6(3) .... 2.33 s.u-Ratio C4B -C9B -C8B 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 120.1(8), Rep 120.0(3) .... 2.67 s.u-Ratio C7C -C6C -C5C 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.7(7), Rep 119.8(3) .... 2.33 s.u-Ratio C6C -C7C -C8C 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.7(7), Rep 119.6(3) .... 2.33 s.u-Ratio C4C -C9C -C8C 1.555 1.555 1.555 PLAT_732 Alert C Angle Calc 119.5(8), Rep 119.6(3) .... 2.67 s.u-Ratio C6D -C7D -C8D 1.555 1.555 1.555 General Notes
FORMU_01 There is a discrepancy between the atom counts in the _chemical_formula_sum and _chemical_formula_moiety. This is usually due to the moiety formula being in the wrong format. Atom count from _chemical_formula_sum: C9 H11.25 N1.25 O2.75 Atom count from _chemical_formula_moiety:C36 H45 N5 O11 REFLT_03 From the CIF: _diffrn_reflns_theta_max 25.03 From the CIF: _reflns_number_total 3450 Count of symmetry unique reflns 3470 Completeness (_total/calc) 99.42% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF.
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
15 Alert Level C = Please check
L-Phenylalanine was obtained from Sigma and used as received. Crystals in the shape of long flat needles were grown by slow evaporation of a dilute nitric acid solution of the amino acid at room temperature.
Three sets of exposures with the detector set at 2θ = 29°, crystal-to-detector distance 4.98 cm. Constrained H-atom refinement with Uiso values set to 1.2Ueq of the carrier atom or 1.5Ueq for the amino groups. The H atom in the shortest hydrogen bond could not be found in difference Fourier maps. It could therefore not be established with certainty whether it is actually bonded to O2A or O2B (a centered position was considered to be less likely). A combined geometric and force-field calculation with the program HYDROGEN (Nardelli, 1999) showed, however, that the H atom is most likely associated with O2A, and it was thus named HO2A. For a 2.44 Å O···O distance, the previously observed lengthening of the covalent O—H bond is about 0.15 Å (Steiner & Saenger, 1994). The HO2A position output by HYDROGEN was consequently adjusted so as to increase the O—H bond length from 0.85 (default) to 1.00 Å. Based on results from a survey of neutron diffraction structures with COOH groups from the Cambridge Structural Database (Allen & Kennard, 1993), the C—O—H angle was furthermore set to 111.5° and the the C—C—O—H torsion angle was increased to 175° (Görbitz, 2001). SAME 0.005 0.005 constraints were used for the four phenylalanine side chains. The absolute structure could not be determined, and Friedel pairs were merged in the final refinements.
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
C9H12NO2+·NO3−·3C9H11NO2 | F(000) = 1536 |
Mr = 180.95 | Dx = 1.373 Mg m−3 |
Monoclinic, C2 | Mo Kα radiation, λ = 0.71073 Å |
a = 30.285 (8) Å | Cell parameters from 3964 reflections |
b = 5.3022 (13) Å | θ = 1.9–25.0° |
c = 22.317 (6) Å | µ = 0.10 mm−1 |
β = 102.263 (4)° | T = 150 K |
V = 3501.9 (15) Å3 | Flat needle, colourless |
Z = 16 | 0.55 × 0.20 × 0.07 mm |
Siemens SMART CCD diffractometer | 3450 independent reflections |
Radiation source: fine-focus sealed tube | 2777 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.100 |
Detector resolution: 8.3 pixels mm-1 | θmax = 25.0°, θmin = 1.9° |
sets of exposures each taken over 0.3° ω rotation scans | h = −36→34 |
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | k = −6→6 |
Tmin = 0.945, Tmax = 0.993 | l = −24→26 |
9411 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)] = 0.113 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.269 | w = 1/[σ2(Fo2) + (0.098P)2 + 3.75P] where P = (Fo2 + 2Fc2)/3 |
S = 1.63 | (Δ/σ)max = 0.005 |
3450 reflections | Δρmax = 0.62 e Å−3 |
474 parameters | Δρmin = −0.54 e Å−3 |
543 restraints | Extinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0053 (14) |
C9H12NO2+·NO3−·3C9H11NO2 | V = 3501.9 (15) Å3 |
Mr = 180.95 | Z = 16 |
Monoclinic, C2 | Mo Kα radiation |
a = 30.285 (8) Å | µ = 0.10 mm−1 |
b = 5.3022 (13) Å | T = 150 K |
c = 22.317 (6) Å | 0.55 × 0.20 × 0.07 mm |
β = 102.263 (4)° |
Siemens SMART CCD diffractometer | 3450 independent reflections |
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | 2777 reflections with I > 2σ(I) |
Tmin = 0.945, Tmax = 0.993 | Rint = 0.100 |
9411 measured reflections |
R[F2 > 2σ(F2)] = 0.113 | 543 restraints |
wR(F2) = 0.269 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.63 | Δρmax = 0.62 e Å−3 |
3450 reflections | Δρmin = −0.54 e Å−3 |
474 parameters |
x | y | z | Uiso*/Ueq | ||
O1A | 0.3062 (2) | 0.3387 (13) | 0.0591 (3) | 0.0298 (15) | |
O2A | 0.3194 (2) | 0.1777 (13) | 0.1536 (3) | 0.0335 (16) | |
HO2A | 0.3151 | 0.3546 | 0.1674 | 0.050* | |
N1A | 0.29139 (18) | −0.1575 (13) | 0.0158 (3) | 0.0210 (16) | |
H1A | 0.2961 | −0.3174 | 0.0037 | 0.032* | |
H2A | 0.2935 | −0.0477 | −0.0149 | 0.032* | |
H3A | 0.2634 | −0.1465 | 0.0243 | 0.032* | |
C1A | 0.3157 (2) | 0.1668 (13) | 0.0959 (3) | 0.0178 (17) | |
C2A | 0.32619 (19) | −0.0934 (13) | 0.0718 (3) | 0.0236 (19) | |
H21A | 0.3246 | −0.2220 | 0.1040 | 0.028* | |
C3A | 0.37314 (18) | −0.1053 (15) | 0.0571 (3) | 0.033 (2) | |
H31A | 0.3806 | −0.2843 | 0.0514 | 0.039* | |
H32A | 0.3721 | −0.0177 | 0.0176 | 0.039* | |
C4A | 0.4108 (2) | 0.0093 (14) | 0.1049 (3) | 0.029 (2) | |
C5A | 0.4215 (3) | −0.0852 (15) | 0.1646 (3) | 0.032 (2) | |
H51A | 0.4056 | −0.2277 | 0.1751 | 0.038* | |
C6A | 0.4549 (3) | 0.0266 (18) | 0.2088 (3) | 0.042 (3) | |
H61A | 0.4621 | −0.0404 | 0.2492 | 0.050* | |
C7A | 0.4775 (3) | 0.2355 (16) | 0.1940 (3) | 0.040 (3) | |
H71A | 0.5001 | 0.3141 | 0.2243 | 0.048* | |
C8A | 0.4673 (3) | 0.3305 (16) | 0.1347 (3) | 0.043 (3) | |
H81A | 0.4830 | 0.4739 | 0.1246 | 0.051* | |
C9A | 0.4340 (3) | 0.2178 (15) | 0.0898 (3) | 0.040 (3) | |
H91A | 0.4273 | 0.2830 | 0.0492 | 0.048* | |
O1B | 0.2901 (2) | 0.3968 (13) | 0.2706 (3) | 0.0302 (15) | |
O2B | 0.3250 (2) | 0.5881 (14) | 0.2045 (3) | 0.0359 (17) | |
N1B | 0.3060 (2) | 0.7650 (15) | 0.3540 (3) | 0.0309 (19) | |
H1B | 0.3121 | 0.9037 | 0.3784 | 0.046* | |
H2B | 0.3223 | 0.6318 | 0.3726 | 0.046* | |
H3B | 0.2760 | 0.7286 | 0.3477 | 0.046* | |
C1B | 0.3115 (3) | 0.5761 (14) | 0.2543 (3) | 0.023 (2) | |
C2B | 0.3184 (2) | 0.8158 (13) | 0.2940 (3) | 0.025 (2) | |
H21B | 0.2974 | 0.9478 | 0.2724 | 0.030* | |
C3B | 0.36626 (19) | 0.9197 (12) | 0.3036 (3) | 0.028 (2) | |
H31B | 0.3737 | 0.9430 | 0.2628 | 0.033* | |
H32B | 0.3668 | 1.0883 | 0.3227 | 0.033* | |
C4B | 0.4029 (2) | 0.7602 (12) | 0.3425 (2) | 0.0198 (18) | |
C5B | 0.4225 (3) | 0.5587 (14) | 0.3174 (3) | 0.029 (2) | |
H51B | 0.4136 | 0.5237 | 0.2748 | 0.035* | |
C6B | 0.4551 (3) | 0.4090 (14) | 0.3541 (3) | 0.033 (2) | |
H61B | 0.4685 | 0.2735 | 0.3366 | 0.040* | |
C7B | 0.4678 (3) | 0.4571 (15) | 0.4161 (3) | 0.031 (2) | |
H71B | 0.4898 | 0.3536 | 0.4414 | 0.037* | |
C8B | 0.4485 (3) | 0.6574 (15) | 0.4415 (3) | 0.033 (2) | |
H81B | 0.4576 | 0.6913 | 0.4841 | 0.039* | |
C9B | 0.4159 (3) | 0.8092 (14) | 0.4049 (3) | 0.030 (2) | |
H91B | 0.4027 | 0.9452 | 0.4226 | 0.036* | |
O1C | 0.2980 (2) | 0.0210 (13) | 0.4784 (3) | 0.0292 (15) | |
O2C | 0.3302 (2) | 0.2695 (14) | 0.4186 (3) | 0.0348 (17) | |
N1C | 0.2911 (2) | 0.3854 (14) | 0.5580 (3) | 0.0249 (17) | |
H1C | 0.2992 | 0.4900 | 0.5908 | 0.037* | |
H2C | 0.2966 | 0.2228 | 0.5703 | 0.037* | |
H3C | 0.2612 | 0.4050 | 0.5414 | 0.037* | |
C1C | 0.3156 (3) | 0.2316 (14) | 0.4652 (3) | 0.0215 (19) | |
C2C | 0.3179 (2) | 0.4485 (13) | 0.5112 (3) | 0.0220 (19) | |
H21C | 0.3036 | 0.5995 | 0.4881 | 0.026* | |
C3C | 0.3661 (2) | 0.5201 (12) | 0.5420 (3) | 0.026 (2) | |
H31C | 0.3831 | 0.5539 | 0.5097 | 0.031* | |
H32C | 0.3651 | 0.6793 | 0.5649 | 0.031* | |
C4C | 0.3918 (2) | 0.3257 (13) | 0.5857 (2) | 0.027 (2) | |
C5C | 0.4210 (3) | 0.1543 (14) | 0.5665 (3) | 0.028 (2) | |
H51C | 0.4253 | 0.1609 | 0.5256 | 0.033* | |
C6C | 0.4437 (3) | −0.0257 (15) | 0.6068 (3) | 0.039 (3) | |
H61C | 0.4622 | −0.1473 | 0.5928 | 0.047* | |
C7C | 0.4395 (3) | −0.0277 (17) | 0.6671 (3) | 0.043 (3) | |
H71C | 0.4558 | −0.1470 | 0.6950 | 0.052* | |
C8C | 0.4112 (3) | 0.1455 (18) | 0.6869 (3) | 0.047 (3) | |
H81C | 0.4080 | 0.1423 | 0.7283 | 0.056* | |
C9C | 0.3876 (3) | 0.3240 (15) | 0.6465 (3) | 0.037 (2) | |
H91C | 0.3687 | 0.4437 | 0.6604 | 0.044* | |
O1D | 0.2777 (2) | 0.4577 (13) | 0.9240 (3) | 0.0289 (15) | |
O2D | 0.3019 (3) | 0.0734 (13) | 0.9050 (3) | 0.0343 (17) | |
N1D | 0.2841 (2) | 0.6584 (11) | 0.8188 (3) | 0.0273 (17) | |
H1D | 0.2920 | 0.7192 | 0.7845 | 0.041* | |
H2D | 0.2977 | 0.7516 | 0.8518 | 0.041* | |
H3D | 0.2536 | 0.6680 | 0.8144 | 0.041* | |
C1D | 0.2928 (3) | 0.2989 (15) | 0.8913 (3) | 0.0235 (19) | |
C2D | 0.29870 (19) | 0.3903 (12) | 0.8283 (3) | 0.0209 (18) | |
H21D | 0.2779 | 0.2876 | 0.7967 | 0.025* | |
C3D | 0.34613 (19) | 0.3540 (12) | 0.8177 (3) | 0.027 (2) | |
H31D | 0.3452 | 0.3784 | 0.7735 | 0.033* | |
H32D | 0.3551 | 0.1769 | 0.8277 | 0.033* | |
C4D | 0.3827 (2) | 0.5236 (14) | 0.8534 (2) | 0.025 (2) | |
C5D | 0.3988 (3) | 0.4946 (18) | 0.9164 (3) | 0.043 (3) | |
H51D | 0.3859 | 0.3695 | 0.9379 | 0.052* | |
C6D | 0.4334 (3) | 0.6461 (19) | 0.9480 (3) | 0.046 (3) | |
H61D | 0.4443 | 0.6228 | 0.9908 | 0.055* | |
C7D | 0.4519 (3) | 0.8308 (17) | 0.9173 (3) | 0.039 (2) | |
H71D | 0.4753 | 0.9363 | 0.9388 | 0.047* | |
C8D | 0.4361 (3) | 0.8612 (17) | 0.8546 (3) | 0.044 (3) | |
H81D | 0.4484 | 0.9906 | 0.8335 | 0.053* | |
C9D | 0.4025 (3) | 0.7039 (15) | 0.8222 (2) | 0.033 (2) | |
H91D | 0.3931 | 0.7198 | 0.7789 | 0.040* | |
O1E | 0.2868 (2) | −0.1140 (14) | 0.6098 (3) | 0.0385 (17) | |
O2E | 0.2882 (3) | 0.1299 (15) | 0.6877 (3) | 0.0401 (19) | |
O3E | 0.3071 (3) | −0.2648 (19) | 0.7011 (4) | 0.060 (2) | |
N1E | 0.2944 (3) | −0.0867 (17) | 0.6663 (3) | 0.0314 (19) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1A | 0.048 (3) | 0.008 (3) | 0.030 (3) | −0.001 (3) | 0.000 (2) | 0.000 (2) |
O2A | 0.057 (4) | 0.008 (3) | 0.033 (3) | −0.002 (3) | 0.004 (3) | −0.003 (3) |
N1A | 0.030 (3) | 0.008 (3) | 0.023 (3) | 0.000 (3) | 0.001 (2) | −0.001 (2) |
C1A | 0.022 (4) | 0.007 (4) | 0.021 (3) | −0.001 (3) | −0.001 (3) | 0.001 (3) |
C2A | 0.038 (4) | 0.006 (4) | 0.024 (3) | −0.002 (3) | 0.001 (3) | 0.001 (3) |
C3A | 0.040 (4) | 0.023 (4) | 0.034 (4) | 0.003 (4) | 0.005 (3) | −0.001 (4) |
C4A | 0.036 (4) | 0.014 (4) | 0.034 (4) | −0.001 (4) | 0.005 (3) | 0.000 (3) |
C5A | 0.041 (4) | 0.024 (4) | 0.032 (4) | −0.001 (4) | 0.008 (3) | 0.001 (4) |
C6A | 0.043 (5) | 0.039 (5) | 0.039 (4) | −0.002 (4) | 0.002 (4) | −0.005 (4) |
C7A | 0.037 (4) | 0.033 (5) | 0.048 (4) | −0.001 (4) | 0.006 (4) | −0.009 (4) |
C8A | 0.043 (5) | 0.030 (5) | 0.053 (5) | −0.005 (4) | 0.006 (4) | −0.002 (4) |
C9A | 0.045 (5) | 0.027 (5) | 0.046 (4) | 0.002 (4) | 0.003 (4) | 0.005 (4) |
O1B | 0.044 (3) | 0.010 (3) | 0.037 (3) | −0.007 (3) | 0.009 (2) | −0.009 (3) |
O2B | 0.054 (3) | 0.018 (3) | 0.035 (3) | −0.006 (3) | 0.007 (2) | −0.006 (2) |
N1B | 0.033 (4) | 0.022 (4) | 0.037 (4) | 0.006 (3) | 0.006 (3) | −0.008 (3) |
C1B | 0.029 (4) | 0.009 (4) | 0.029 (4) | 0.002 (3) | −0.001 (3) | 0.001 (3) |
C2B | 0.037 (4) | 0.013 (4) | 0.024 (4) | 0.003 (4) | 0.002 (3) | −0.002 (3) |
C3B | 0.038 (4) | 0.012 (4) | 0.032 (4) | 0.004 (4) | 0.004 (3) | −0.002 (3) |
C4B | 0.024 (4) | 0.009 (4) | 0.027 (4) | −0.005 (3) | 0.006 (3) | −0.005 (3) |
C5B | 0.037 (4) | 0.020 (4) | 0.028 (4) | 0.002 (4) | 0.002 (3) | 0.001 (3) |
C6B | 0.038 (4) | 0.018 (4) | 0.043 (4) | 0.001 (4) | 0.006 (3) | −0.006 (4) |
C7B | 0.029 (4) | 0.026 (4) | 0.036 (4) | 0.005 (4) | 0.003 (3) | 0.001 (4) |
C8B | 0.034 (4) | 0.027 (4) | 0.035 (4) | −0.004 (4) | 0.003 (3) | −0.002 (4) |
C9B | 0.029 (4) | 0.025 (4) | 0.035 (4) | 0.000 (4) | 0.007 (3) | −0.005 (4) |
O1C | 0.041 (3) | 0.007 (3) | 0.037 (3) | −0.004 (3) | 0.001 (3) | −0.003 (3) |
O2C | 0.048 (4) | 0.020 (3) | 0.036 (3) | 0.005 (3) | 0.009 (3) | −0.005 (3) |
N1C | 0.033 (3) | 0.009 (3) | 0.031 (3) | −0.001 (3) | 0.003 (3) | −0.002 (3) |
C1C | 0.029 (4) | 0.008 (4) | 0.024 (4) | −0.003 (3) | −0.001 (3) | −0.002 (3) |
C2C | 0.024 (4) | 0.010 (4) | 0.031 (4) | 0.004 (3) | 0.003 (3) | 0.000 (3) |
C3C | 0.034 (4) | 0.011 (4) | 0.033 (4) | 0.000 (4) | 0.007 (3) | 0.001 (3) |
C4C | 0.028 (4) | 0.023 (4) | 0.028 (4) | −0.008 (4) | 0.002 (3) | −0.004 (3) |
C5C | 0.025 (4) | 0.021 (4) | 0.035 (4) | −0.001 (4) | 0.001 (3) | 0.000 (4) |
C6C | 0.044 (5) | 0.023 (4) | 0.047 (4) | −0.001 (4) | 0.003 (4) | −0.007 (4) |
C7C | 0.047 (5) | 0.032 (5) | 0.048 (4) | 0.004 (4) | 0.005 (4) | 0.006 (4) |
C8C | 0.049 (5) | 0.049 (5) | 0.041 (4) | 0.004 (5) | 0.007 (4) | 0.006 (4) |
C9C | 0.044 (5) | 0.027 (5) | 0.038 (4) | 0.004 (4) | 0.008 (3) | 0.003 (4) |
O1D | 0.042 (3) | 0.017 (3) | 0.030 (3) | −0.002 (3) | 0.013 (2) | −0.003 (3) |
O2D | 0.058 (4) | 0.008 (3) | 0.036 (3) | −0.006 (3) | 0.008 (3) | 0.001 (3) |
N1D | 0.039 (4) | 0.009 (3) | 0.031 (3) | 0.001 (3) | 0.001 (3) | 0.000 (3) |
C1D | 0.031 (4) | 0.013 (4) | 0.026 (4) | −0.005 (4) | 0.004 (3) | −0.003 (3) |
C2D | 0.026 (3) | 0.008 (3) | 0.025 (3) | 0.000 (3) | −0.001 (3) | −0.001 (3) |
C3D | 0.038 (4) | 0.012 (4) | 0.031 (4) | 0.002 (4) | 0.006 (3) | 0.005 (3) |
C4D | 0.031 (4) | 0.020 (4) | 0.028 (4) | −0.002 (4) | 0.009 (3) | 0.000 (3) |
C5D | 0.050 (5) | 0.038 (5) | 0.041 (4) | −0.011 (4) | 0.009 (4) | 0.007 (4) |
C6D | 0.047 (5) | 0.048 (5) | 0.043 (4) | −0.005 (4) | 0.011 (4) | 0.002 (4) |
C7D | 0.037 (4) | 0.027 (5) | 0.049 (4) | −0.001 (4) | 0.002 (4) | −0.003 (4) |
C8D | 0.042 (5) | 0.035 (5) | 0.052 (5) | −0.002 (4) | 0.006 (4) | 0.011 (4) |
C9D | 0.034 (4) | 0.025 (4) | 0.040 (4) | −0.001 (4) | 0.004 (3) | 0.008 (4) |
O1E | 0.061 (4) | 0.016 (3) | 0.037 (3) | 0.001 (3) | 0.009 (3) | 0.000 (3) |
O2E | 0.048 (4) | 0.028 (4) | 0.044 (3) | −0.004 (3) | 0.008 (3) | −0.015 (3) |
O3E | 0.072 (5) | 0.046 (4) | 0.062 (4) | 0.016 (4) | 0.015 (3) | 0.025 (4) |
N1E | 0.040 (4) | 0.019 (4) | 0.035 (4) | 0.006 (4) | 0.007 (3) | 0.003 (3) |
O1A—C1A | 1.219 (10) | O2C—C1C | 1.230 (9) |
O2A—C1A | 1.271 (9) | N1C—C2C | 1.489 (6) |
O2A—HO2A | 1.0042 | N1C—H1C | 0.9100 |
N1A—C2A | 1.494 (6) | N1C—H2C | 0.9100 |
N1A—H1A | 0.9100 | N1C—H3C | 0.9100 |
N1A—H2A | 0.9100 | C1C—C2C | 1.534 (7) |
N1A—H3A | 0.9100 | C2C—C3C | 1.523 (7) |
C1A—C2A | 1.538 (7) | C2C—H21C | 1.0000 |
C2A—C3A | 1.527 (7) | C3C—C4C | 1.516 (6) |
C2A—H21A | 1.0000 | C3C—H31C | 0.9900 |
C3A—C4A | 1.515 (6) | C3C—H32C | 0.9900 |
C3A—H31A | 0.9900 | C4C—C9C | 1.389 (7) |
C3A—H32A | 0.9900 | C4C—C5C | 1.397 (6) |
C4A—C9A | 1.389 (7) | C5C—C6C | 1.389 (6) |
C4A—C5A | 1.395 (6) | C5C—H51C | 0.9500 |
C5A—C6A | 1.388 (6) | C6C—C7C | 1.380 (8) |
C5A—H51A | 0.9500 | C6C—H61C | 0.9500 |
C6A—C7A | 1.380 (8) | C7C—C8C | 1.390 (6) |
C6A—H61A | 0.9500 | C7C—H71C | 0.9500 |
C7A—C8A | 1.388 (6) | C8C—C9C | 1.396 (6) |
C7A—H71A | 0.9500 | C8C—H81C | 0.9500 |
C8A—C9A | 1.396 (6) | C9C—H91C | 0.9500 |
C8A—H81A | 0.9500 | O1D—C1D | 1.261 (10) |
C9A—H91A | 0.9500 | O2D—C1D | 1.250 (10) |
O1B—C1B | 1.247 (10) | N1D—C2D | 1.491 (6) |
O2B—C1B | 1.265 (9) | N1D—H1D | 0.9100 |
N1B—C2B | 1.490 (6) | N1D—H2D | 0.9100 |
N1B—H1B | 0.9100 | N1D—H3D | 0.9100 |
N1B—H2B | 0.9100 | C1D—C2D | 1.535 (6) |
N1B—H3B | 0.9100 | C2D—C3D | 1.516 (7) |
C1B—C2B | 1.538 (7) | C2D—H21D | 1.0000 |
C2B—C3B | 1.521 (7) | C3D—C4D | 1.514 (6) |
C2B—H21B | 1.0000 | C3D—H31D | 0.9900 |
C3B—C4B | 1.515 (6) | C3D—H32D | 0.9900 |
C3B—H31B | 0.9900 | C4D—C9D | 1.390 (7) |
C3B—H32B | 0.9900 | C4D—C5D | 1.396 (6) |
C4B—C9B | 1.389 (7) | C5D—C6D | 1.389 (6) |
C4B—C5B | 1.396 (6) | C5D—H51D | 0.9500 |
C5B—C6B | 1.389 (6) | C6D—C7D | 1.381 (8) |
C5B—H51B | 0.9500 | C6D—H61D | 0.9500 |
C6B—C7B | 1.379 (8) | C7D—C8D | 1.388 (6) |
C6B—H61B | 0.9500 | C7D—H71D | 0.9500 |
C7B—C8B | 1.389 (6) | C8D—C9D | 1.394 (6) |
C7B—H71B | 0.9500 | C8D—H81D | 0.9500 |
C8B—C9B | 1.395 (6) | C9D—H91D | 0.9500 |
C8B—H81B | 0.9500 | O1E—N1E | 1.243 (9) |
C9B—H91B | 0.9500 | O2E—N1E | 1.272 (11) |
O1C—C1C | 1.298 (10) | O3E—N1E | 1.230 (12) |
C1A—O2A—HO2A | 111.3 | C2C—N1C—H2C | 109.5 |
C2A—N1A—H1A | 109.5 | H1C—N1C—H2C | 109.5 |
C2A—N1A—H2A | 109.5 | C2C—N1C—H3C | 109.5 |
H1A—N1A—H2A | 109.5 | H1C—N1C—H3C | 109.5 |
C2A—N1A—H3A | 109.5 | H2C—N1C—H3C | 109.5 |
H1A—N1A—H3A | 109.5 | O2C—C1C—O1C | 124.9 (6) |
H2A—N1A—H3A | 109.5 | O2C—C1C—C2C | 118.1 (6) |
O1A—C1A—O2A | 127.3 (7) | O1C—C1C—C2C | 117.0 (5) |
O1A—C1A—C2A | 118.2 (6) | N1C—C2C—C3C | 110.6 (4) |
O2A—C1A—C2A | 114.5 (6) | N1C—C2C—C1C | 110.3 (5) |
N1A—C2A—C3A | 109.5 (4) | C3C—C2C—C1C | 113.0 (4) |
N1A—C2A—C1A | 109.6 (4) | N1C—C2C—H21C | 107.6 |
C3A—C2A—C1A | 112.6 (4) | C3C—C2C—H21C | 107.6 |
N1A—C2A—H21A | 108.4 | C1C—C2C—H21C | 107.6 |
C3A—C2A—H21A | 108.4 | C4C—C3C—C2C | 115.7 (4) |
C1A—C2A—H21A | 108.4 | C4C—C3C—H31C | 108.4 |
C4A—C3A—C2A | 115.4 (4) | C2C—C3C—H31C | 108.4 |
C4A—C3A—H31A | 108.4 | C4C—C3C—H32C | 108.4 |
C2A—C3A—H31A | 108.4 | C2C—C3C—H32C | 108.4 |
C4A—C3A—H32A | 108.4 | H31C—C3C—H32C | 107.4 |
C2A—C3A—H32A | 108.4 | C9C—C4C—C5C | 119.4 (3) |
H31A—C3A—H32A | 107.5 | C9C—C4C—C3C | 119.4 (4) |
C9A—C4A—C5A | 119.5 (3) | C5C—C4C—C3C | 121.1 (4) |
C9A—C4A—C3A | 119.4 (4) | C6C—C5C—C4C | 120.5 (4) |
C5A—C4A—C3A | 121.0 (4) | C6C—C5C—H51C | 119.8 |
C6A—C5A—C4A | 120.7 (4) | C4C—C5C—H51C | 119.8 |
C6A—C5A—H51A | 119.6 | C7C—C6C—C5C | 120.0 (3) |
C4A—C5A—H51A | 119.6 | C7C—C6C—H61C | 120.0 |
C7A—C6A—C5A | 119.8 (3) | C5C—C6C—H61C | 120.0 |
C7A—C6A—H61A | 120.1 | C6C—C7C—C8C | 119.8 (3) |
C5A—C6A—H61A | 120.1 | C6C—C7C—H71C | 120.1 |
C6A—C7A—C8A | 119.8 (3) | C8C—C7C—H71C | 120.1 |
C6A—C7A—H71A | 120.1 | C7C—C8C—C9C | 120.6 (4) |
C8A—C7A—H71A | 120.1 | C7C—C8C—H81C | 119.7 |
C7A—C8A—C9A | 120.7 (4) | C9C—C8C—H81C | 119.7 |
C7A—C8A—H81A | 119.6 | C4C—C9C—C8C | 119.6 (3) |
C9A—C8A—H81A | 119.6 | C4C—C9C—H91C | 120.2 |
C4A—C9A—C8A | 119.4 (3) | C8C—C9C—H91C | 120.2 |
C4A—C9A—H91A | 120.3 | C2D—N1D—H1D | 109.5 |
C8A—C9A—H91A | 120.3 | C2D—N1D—H2D | 109.5 |
C2B—N1B—H1B | 109.5 | H1D—N1D—H2D | 109.5 |
C2B—N1B—H2B | 109.5 | C2D—N1D—H3D | 109.5 |
H1B—N1B—H2B | 109.5 | H1D—N1D—H3D | 109.5 |
C2B—N1B—H3B | 109.5 | H2D—N1D—H3D | 109.5 |
H1B—N1B—H3B | 109.5 | O2D—C1D—O1D | 125.9 (6) |
H2B—N1B—H3B | 109.5 | O2D—C1D—C2D | 117.5 (7) |
O1B—C1B—O2B | 125.4 (6) | O1D—C1D—C2D | 116.5 (6) |
O1B—C1B—C2B | 118.5 (6) | N1D—C2D—C3D | 111.2 (4) |
O2B—C1B—C2B | 115.8 (6) | N1D—C2D—C1D | 110.0 (4) |
N1B—C2B—C3B | 110.8 (4) | C3D—C2D—C1D | 113.7 (4) |
N1B—C2B—C1B | 109.8 (5) | N1D—C2D—H21D | 107.2 |
C3B—C2B—C1B | 112.9 (4) | C3D—C2D—H21D | 107.2 |
N1B—C2B—H21B | 107.7 | C1D—C2D—H21D | 107.2 |
C3B—C2B—H21B | 107.7 | C2D—C3D—C4D | 117.0 (4) |
C1B—C2B—H21B | 107.7 | C2D—C3D—H31D | 108.0 |
C4B—C3B—C2B | 116.0 (4) | C4D—C3D—H31D | 108.0 |
C4B—C3B—H31B | 108.3 | C2D—C3D—H32D | 108.0 |
C2B—C3B—H31B | 108.3 | C4D—C3D—H32D | 108.0 |
C4B—C3B—H32B | 108.3 | H31D—C3D—H32D | 107.3 |
C2B—C3B—H32B | 108.3 | C9D—C4D—C5D | 119.0 (3) |
H31B—C3B—H32B | 107.4 | C9D—C4D—C3D | 119.3 (4) |
C9B—C4B—C5B | 119.4 (3) | C5D—C4D—C3D | 121.5 (4) |
C9B—C4B—C3B | 119.2 (3) | C6D—C5D—C4D | 120.9 (4) |
C5B—C4B—C3B | 121.3 (4) | C6D—C5D—H51D | 119.6 |
C6B—C5B—C4B | 120.6 (4) | C4D—C5D—H51D | 119.6 |
C6B—C5B—H51B | 119.7 | C7D—C6D—C5D | 119.9 (3) |
C4B—C5B—H51B | 119.7 | C7D—C6D—H61D | 120.0 |
C7B—C6B—C5B | 119.9 (3) | C5D—C6D—H61D | 120.0 |
C7B—C6B—H61B | 120.0 | C6D—C7D—C8D | 119.6 (3) |
C5B—C6B—H61B | 120.0 | C6D—C7D—H71D | 120.2 |
C6B—C7B—C8B | 119.8 (3) | C8D—C7D—H71D | 120.2 |
C6B—C7B—H71B | 120.1 | C7D—C8D—C9D | 120.7 (4) |
C8B—C7B—H71B | 120.1 | C7D—C8D—H81D | 119.6 |
C7B—C8B—C9B | 120.6 (4) | C9D—C8D—H81D | 119.6 |
C7B—C8B—H81B | 119.7 | C4D—C9D—C8D | 119.8 (3) |
C9B—C8B—H81B | 119.7 | C4D—C9D—H91D | 120.1 |
C4B—C9B—C8B | 119.6 (3) | C8D—C9D—H91D | 120.1 |
C4B—C9B—H91B | 120.2 | O3E—N1E—O1E | 121.1 (9) |
C8B—C9B—H91B | 120.2 | O3E—N1E—O2E | 120.5 (8) |
C2C—N1C—H1C | 109.5 | O1E—N1E—O2E | 118.4 (8) |
O1A—C1A—C2A—N1A | −46.3 (8) | O2C—C1C—C2C—N1C | 169.3 (7) |
O2A—C1A—C2A—N1A | 135.9 (6) | O1C—C1C—C2C—N1C | −10.3 (9) |
O1A—C1A—C2A—C3A | 75.9 (8) | O2C—C1C—C2C—C3C | −66.3 (9) |
O2A—C1A—C2A—C3A | −101.9 (7) | O1C—C1C—C2C—C3C | 114.1 (7) |
N1A—C2A—C3A—C4A | 167.2 (6) | N1C—C2C—C3C—C4C | 55.8 (7) |
C1A—C2A—C3A—C4A | 45.1 (8) | C1C—C2C—C3C—C4C | −68.4 (6) |
C2A—C3A—C4A—C9A | −116.4 (8) | C2C—C3C—C4C—C9C | −86.2 (9) |
C2A—C3A—C4A—C5A | 61.0 (10) | C2C—C3C—C4C—C5C | 96.2 (8) |
C9A—C4A—C5A—C6A | −0.1 (14) | C9C—C4C—C5C—C6C | 3.5 (13) |
C3A—C4A—C5A—C6A | −177.5 (9) | C3C—C4C—C5C—C6C | −178.8 (8) |
C4A—C5A—C6A—C7A | 0.8 (16) | C4C—C5C—C6C—C7C | −3.4 (15) |
C5A—C6A—C7A—C8A | −0.9 (16) | C5C—C6C—C7C—C8C | 2.1 (16) |
C6A—C7A—C8A—C9A | 0.3 (16) | C6C—C7C—C8C—C9C | −0.9 (17) |
C5A—C4A—C9A—C8A | −0.6 (15) | C5C—C4C—C9C—C8C | −2.3 (14) |
C3A—C4A—C9A—C8A | 176.9 (9) | C3C—C4C—C9C—C8C | −180.0 (9) |
C7A—C8A—C9A—C4A | 0.4 (16) | C7C—C8C—C9C—C4C | 1.0 (17) |
O1B—C1B—C2B—N1B | 12.4 (9) | O2D—C1D—C2D—N1D | 177.2 (7) |
O2B—C1B—C2B—N1B | −173.5 (7) | O1D—C1D—C2D—N1D | −0.7 (9) |
O1B—C1B—C2B—C3B | 136.6 (7) | O2D—C1D—C2D—C3D | −57.4 (9) |
O2B—C1B—C2B—C3B | −49.3 (9) | O1D—C1D—C2D—C3D | 124.7 (7) |
N1B—C2B—C3B—C4B | 55.4 (7) | N1D—C2D—C3D—C4D | 53.5 (7) |
C1B—C2B—C3B—C4B | −68.2 (6) | C1D—C2D—C3D—C4D | −71.3 (6) |
C2B—C3B—C4B—C9B | −93.8 (8) | C2D—C3D—C4D—C9D | −112.0 (8) |
C2B—C3B—C4B—C5B | 83.5 (8) | C2D—C3D—C4D—C5D | 71.5 (10) |
C9B—C4B—C5B—C6B | −0.5 (14) | C9D—C4D—C5D—C6D | 1.3 (16) |
C3B—C4B—C5B—C6B | −177.8 (8) | C3D—C4D—C5D—C6D | 177.8 (9) |
C4B—C5B—C6B—C7B | 0.8 (15) | C4D—C5D—C6D—C7D | 0.9 (18) |
C5B—C6B—C7B—C8B | −0.8 (15) | C5D—C6D—C7D—C8D | −0.9 (18) |
C6B—C7B—C8B—C9B | 0.7 (15) | C6D—C7D—C8D—C9D | −1.4 (17) |
C5B—C4B—C9B—C8B | 0.3 (13) | C5D—C4D—C9D—C8D | −3.5 (15) |
C3B—C4B—C9B—C8B | 177.7 (8) | C3D—C4D—C9D—C8D | 179.9 (9) |
C7B—C8B—C9B—C4B | −0.4 (15) | C7D—C8D—C9D—C4D | 3.6 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2A—HO2A···O2B | 1.00 | 1.49 | 2.443 (9) | 158 |
N1A—H1A···O1Di | 0.91 | 2.11 | 2.858 (8) | 138 |
N1A—H1A···O1Aii | 0.91 | 2.19 | 2.844 (10) | 128 |
N1A—H2A···O2Diii | 0.91 | 1.97 | 2.837 (9) | 159 |
N1A—H3A···O1Div | 0.91 | 1.95 | 2.785 (9) | 152 |
N1A—H3A···O1Av | 0.91 | 2.50 | 3.071 (8) | 121 |
N1B—H1B···O2Cvi | 0.91 | 2.16 | 3.053 (10) | 167 |
N1B—H2B···O2C | 0.91 | 2.17 | 3.012 (10) | 154 |
N1B—H3B···O2Evii | 0.91 | 2.01 | 2.898 (10) | 166 |
N1C—H1C···O1Evi | 0.91 | 2.19 | 2.909 (10) | 135 |
N1C—H2C···O1E | 0.91 | 2.04 | 2.903 (10) | 158 |
N1C—H3C···O1Cvii | 0.91 | 1.86 | 2.744 (9) | 164 |
N1D—H1D···O3Evi | 0.91 | 2.01 | 2.886 (10) | 161 |
N1D—H2D···O2Dvi | 0.91 | 2.07 | 2.896 (9) | 151 |
N1D—H3D···O1Bvii | 0.91 | 2.40 | 2.954 (9) | 119 |
N1D—H3D···O2Avii | 0.91 | 2.46 | 3.322 (10) | 157 |
Symmetry codes: (i) x, y−1, z−1; (ii) x, y−1, z; (iii) x, y, z−1; (iv) −x+1/2, y−1/2, −z+1; (v) −x+1/2, y−1/2, −z; (vi) x, y+1, z; (vii) −x+1/2, y+1/2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C9H12NO2+·NO3−·3C9H11NO2 |
Mr | 180.95 |
Crystal system, space group | Monoclinic, C2 |
Temperature (K) | 150 |
a, b, c (Å) | 30.285 (8), 5.3022 (13), 22.317 (6) |
β (°) | 102.263 (4) |
V (Å3) | 3501.9 (15) |
Z | 16 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.55 × 0.20 × 0.07 |
Data collection | |
Diffractometer | Siemens SMART CCD diffractometer |
Absorption correction | Empirical (using intensity measurements) (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.945, 0.993 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9411, 3450, 2777 |
Rint | 0.100 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.113, 0.269, 1.63 |
No. of reflections | 3450 |
No. of parameters | 474 |
No. of restraints | 543 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.62, −0.54 |
Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SAINT, SHELXTL (Sheldrick, 1997), SHELXTL.
O1A—C1A | 1.219 (10) | O1C—C1C | 1.298 (10) |
O2A—C1A | 1.271 (9) | O2C—C1C | 1.230 (9) |
N1A—C2A | 1.494 (6) | N1C—C2C | 1.489 (6) |
O1B—C1B | 1.247 (10) | O1D—C1D | 1.261 (10) |
O2B—C1B | 1.265 (9) | O2D—C1D | 1.250 (10) |
N1B—C2B | 1.490 (6) | N1D—C2D | 1.491 (6) |
O1A—C1A—O2A | 127.3 (7) | O2C—C1C—O1C | 124.9 (6) |
O1A—C1A—C2A | 118.2 (6) | O2C—C1C—C2C | 118.1 (6) |
O2A—C1A—C2A | 114.5 (6) | O1C—C1C—C2C | 117.0 (5) |
O1B—C1B—O2B | 125.4 (6) | O2D—C1D—O1D | 125.9 (6) |
O1B—C1B—C2B | 118.5 (6) | O2D—C1D—C2D | 117.5 (7) |
O2B—C1B—C2B | 115.8 (6) | O1D—C1D—C2D | 116.5 (6) |
O1A—C1A—C2A—N1A | −46.3 (8) | O1C—C1C—C2C—N1C | −10.3 (9) |
N1A—C2A—C3A—C4A | 167.2 (6) | N1C—C2C—C3C—C4C | 55.8 (7) |
C2A—C3A—C4A—C5A | 61.0 (10) | C2C—C3C—C4C—C5C | 96.2 (8) |
O1B—C1B—C2B—N1B | 12.4 (9) | O1D—C1D—C2D—N1D | −0.7 (9) |
N1B—C2B—C3B—C4B | 55.4 (7) | N1D—C2D—C3D—C4D | 53.5 (7) |
C2B—C3B—C4B—C5B | 83.5 (8) | C2D—C3D—C4D—C5D | 71.5 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2A—HO2A···O2B | 1.00 | 1.49 | 2.443 (9) | 158 |
N1A—H1A···O1Di | 0.91 | 2.11 | 2.858 (8) | 138 |
N1A—H1A···O1Aii | 0.91 | 2.19 | 2.844 (10) | 128 |
N1A—H2A···O2Diii | 0.91 | 1.97 | 2.837 (9) | 159 |
N1A—H3A···O1Div | 0.91 | 1.95 | 2.785 (9) | 152 |
N1A—H3A···O1Av | 0.91 | 2.50 | 3.071 (8) | 121 |
N1B—H1B···O2Cvi | 0.91 | 2.16 | 3.053 (10) | 167 |
N1B—H2B···O2C | 0.91 | 2.17 | 3.012 (10) | 154 |
N1B—H3B···O2Evii | 0.91 | 2.01 | 2.898 (10) | 166 |
N1C—H1C···O1Evi | 0.91 | 2.19 | 2.909 (10) | 135 |
N1C—H2C···O1E | 0.91 | 2.04 | 2.903 (10) | 158 |
N1C—H3C···O1Cvii | 0.91 | 1.86 | 2.744 (9) | 164 |
N1D—H1D···O3Evi | 0.91 | 2.01 | 2.886 (10) | 161 |
N1D—H2D···O2Dvi | 0.91 | 2.07 | 2.896 (9) | 151 |
N1D—H3D···O1Bvii | 0.91 | 2.40 | 2.954 (9) | 119 |
N1D—H3D···O2Avii | 0.91 | 2.46 | 3.322 (10) | 157 |
Symmetry codes: (i) x, y−1, z−1; (ii) x, y−1, z; (iii) x, y, z−1; (iv) −x+1/2, y−1/2, −z+1; (v) −x+1/2, y−1/2, −z; (vi) x, y+1, z; (vii) −x+1/2, y+1/2, −z+1. |
The title compound, (I), was studied as part of a search for good crystallization conditions for various peptides. Several nice-looking crystals were obtained, but the diffraction patterns revealed that the structure was probably divided into layers that were misaligned along one axis. This made the unit-cell determination difficult, and only after testing several specimens was it possible to find the third axis, collect diffraction data and integrate them successfully.
As a result of the poor crystal quality, the final R factor is high for a small molecule structure. Nevertheless, the structure proved to be interesting in having an odd sequence of four phenylalanine molecules in the asymmetric unit in addition to the nitrate anion (Fig. 1). Three of the phenylalanines (B, C and D) are in the zwitterionic form. The positive charge most likely (see below) resides with the last amino acid molecule A, which is connected to molecule B by a very short –COOH···-OOC– hydrogen bond (Table 2). The shortness of this interaction can in part be attributed to the fact that the carboxylate group of molecule B participates in no other strong interactions, a most unusual incidence. The COOH group of molecule A is furthermore involved in only one additional hydrogen bond with an H···O distance less than 2.50 Å.
The molecular packing shown in Fig. 2 has, as suspected, thick hydrophobic layers of L-phenylalanine side chains, and also hydrophilic layers composed of two interconnected hydrogen-bonded sheets. This is a very persistent pattern, which occurs not only in the structure of phenylalanine itself (Weissbuch et al., 1990) and its complexes with mandelic acid (Okamura et al., 1997), but also in other salts such as L-phenylalanine hydrochloride (Al-Karaghouli & Koetzle, 1975), L-phenylalnine L-phenylalaninium formate (Görbitz & Etter, 1992) and L-phenylalanine L-phenylalaninium perchlorate (Srinivasan & Rajaram, 1997). It is noteworthy that the latter two structures include one L-phenylalanine zwitterion and one L-phenylalaninium cation in the asymmetric unit, which are in both cases connected by a very short hydrogen bond like the one seen in the title structure.