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_1505342
_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            'C12 H16 N2 O3'
_chemical_formula_weight         236.27
_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                 92.408(7)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   13.9345(12)
_cell_length_b                   5.5848(5)
_cell_length_c                   15.4060(13)
_cell_measurement_temperature    150(2)
_cell_volume                     1197.86(18)
_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 0.938
_diffrn_measured_fraction_theta_max 0.938
_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  0.0141
_diffrn_reflns_av_sigmaI/netI    0.0292
_diffrn_reflns_limit_h_max       19
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       4
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            7558
_diffrn_reflns_theta_full        30.07
_diffrn_reflns_theta_max         30.07
_diffrn_reflns_theta_min         2.93
_exptl_absorpt_coefficient_mu    0.095
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            white
_exptl_crystal_density_diffrn    1.310
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             504
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.05
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.232
_refine_diff_density_min         -0.160
_refine_diff_density_rms         0.035
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.1(7)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.851
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     309
_refine_ls_number_reflns         4404
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.851
_refine_ls_R_factor_all          0.0392
_refine_ls_R_factor_gt           0.0317
_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^)+(0.0753P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3 
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0876
_refine_ls_wR_factor_ref         0.0901
_reflns_number_gt                3691
_reflns_number_total             4404
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol0701870si20070124_104804.cif
_cod_data_source_block           x
_cod_original_sg_symbol_H-M      P21
_cod_database_code               1505342