A new molecular scaffold for the formation of supramolecular peptide double helices: the crystallographic insight.
Guha, Samit; Drew, Michael G. B.; Banerjee, Arindam; Organic letters 9 (2007) 1347–1350; doi:10.1021/ol0701870

data_1505340
_publ_section_title
;
 A new molecular scaffold for the formation of supramolecular peptide
 double helices: the crystallographic insight.
;
_journal_issue                   7
_journal_name_full               'Organic letters'
_journal_page_first              1347
_journal_page_last               1350
_journal_paper_doi               10.1021/ol0701870
_journal_volume                  9
_journal_year                    2007
_chemical_formula_sum            'C8 H16 N2 O3'
_chemical_formula_weight         188.23
_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_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                 91.345(10)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   11.1153(15)
_cell_length_b                   5.4908(8)
_cell_length_c                   16.1643(17)
_cell_measurement_temperature    150(2)
_cell_volume                     986.3(2)
_computing_cell_refinement       'Crysalis, Oxford Diffraction'
_computing_data_collection       'Crysalis, Oxford Diffraction'
_computing_data_reduction        'Crysalis, Oxford Diffraction'
_computing_molecular_graphics    PLATON(Spek,2004)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      150(2)
_diffrn_measured_fraction_theta_full 0.968
_diffrn_measured_fraction_theta_max 0.968
_diffrn_measurement_device       'Oxford Diffaction X-Calibur System'
_diffrn_measurement_method       '321 frames, counting time 10 s.'
_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  0.0924
_diffrn_reflns_av_sigmaI/netI    0.2166
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -5
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            5708
_diffrn_reflns_theta_full        29.99
_diffrn_reflns_theta_max         29.99
_diffrn_reflns_theta_min         3.08
_exptl_absorpt_coefficient_mu    0.097
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            white
_exptl_crystal_density_diffrn    1.268
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             408
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.05
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.511
_refine_diff_density_min         -0.436
_refine_diff_density_rms         0.084
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -3(2)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.749
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     241
_refine_ls_number_reflns         3605
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.749
_refine_ls_R_factor_all          0.1322
_refine_ls_R_factor_gt           0.0683
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
;
_refine_ls_weighting_details 
  w=1/[\s^2^(Fo^2^)+(0.0846P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3 
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1548
_refine_ls_wR_factor_ref         0.1645
_reflns_number_gt                1297
_reflns_number_total             3605
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol0701870si20070124_104634.cif
_cod_data_source_block           x
_cod_original_sg_symbol_H-M      P21/c
_cod_database_code               1505340