Micropores in crystalline dipeptides as seen from the crystal structure, He pycnometry, and 129Xe NMR spectroscopy.
Soldatov, Dmitriy V; Moudrakovski, Igor L; Grachev, Eugeny V; Ripmeester, John A; Journal of the American Chemical Society 128 (2006) 6737–6744; doi:10.1021/ja060474j

data_4101257
_publ_section_title
;
 Micropores in crystalline dipeptides as seen from the crystal
 structure, He pycnometry, and 129Xe NMR spectroscopy.
;
_journal_issue                   20
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              6737
_journal_page_last               6744
_journal_paper_doi               10.1021/ja060474j
_journal_volume                  128
_journal_year                    2006
_chemical_formula_sum            'C10 H20 N2 O3'
_chemical_formula_weight         216.28
_chemical_name_common            Val-Val
_chemical_name_systematic
;
 L-Valyl-L-Valine
;
_space_group_IT_number           169
_symmetry_cell_setting           hexagonal
_symmetry_space_group_name_Hall  'P 61'
_symmetry_space_group_name_H-M   'P 61'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                120.00
_cell_formula_units_Z            6
_cell_length_a                   14.573(2)
_cell_length_b                   14.573(2)
_cell_length_c                   10.354(1)
_cell_measurement_reflns_used    5465
_cell_measurement_temperature    293(2)
_cell_volume                     1904.3(4)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.986
_diffrn_measured_fraction_theta_max 0.986
_diffrn_measurement_device_type  'SMART CCD'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0206
_diffrn_reflns_av_sigmaI/netI    0.0128
_diffrn_reflns_limit_h_max       19
_diffrn_reflns_limit_h_min       -19
_diffrn_reflns_limit_k_max       19
_diffrn_reflns_limit_k_min       -19
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            21975
_diffrn_reflns_theta_full        28.75
_diffrn_reflns_theta_max         28.75
_diffrn_reflns_theta_min         2.54
_exptl_absorpt_coefficient_mu    0.083
_exptl_crystal_colour            white
_exptl_crystal_density_diffrn    1.132
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             708
_exptl_crystal_size_max          0.9
_exptl_crystal_size_mid          0.2
_exptl_crystal_size_min          0.1
_refine_diff_density_max         0.183
_refine_diff_density_min         -0.118
_refine_diff_density_rms         0.028
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.4(7)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.044
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     141
_refine_ls_number_reflns         3216
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.044
_refine_ls_R_factor_all          0.0329
_refine_ls_R_factor_gt           0.0304
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0501P)^2^+0.1061P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0774
_refine_ls_wR_factor_ref         0.0786
_reflns_number_gt                3041
_reflns_number_total             3216
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja060474jsi20060127_030443.cif
_cod_data_source_block           vv
_cod_original_sg_symbol_H-M      P61
_cod_database_code               4101257