Leucopterin, the white pigment in butterfly wings: structural analysis by PDF fit, FIDEL fit, Rietveld refinement, solid-state NMR and DFT-D.
Bravetti, Federica; Tapmeyer, Lukas; Skorodumov, Kathrin; Alig, Edith; Habermehl, Stefan; Hühn, Robert; Bordignon, Simone; Gallo, Angelo; Nervi, Carlo; Chierotti, Michele R.; Schmidt, Martin U.; IUCrJ 10 (2023) 448–463; doi:10.1107/S2052252523004281

data_1569410
_publ_section_title
;
 Leucopterin, the white pigment in butterfly wings: structural analysis by
 PDF fit, FIDEL fit, Rietveld refinement, solid-state NMR and DFT-D.
;
_journal_coeditor_code           LT5058
_journal_issue                   4
_journal_name_full               IUCrJ
_journal_page_first              448
_journal_page_last               463
_journal_paper_doi               10.1107/S2052252523004281
_journal_volume                  10
_journal_year                    2023
_chemical_formula_moiety         '2(C6 H5 N5 O3), H2 O'
_chemical_formula_sum            'C12 H12 N10 O7'
_chemical_formula_weight         408.32
_chemical_melting_point          'dehydration starting at 130 C'
_chemical_name_systematic        'Leucopterin hemihydrate'
_space_group_crystal_system      monoclinic
_space_group_IT_number           13
_space_group_name_Hall           '-P 2yc'
_space_group_name_H-M_alt        'P 1 2/c 1'
_audit_creation_method           SHELXL-2018/3
_cell_angle_alpha                90
_cell_angle_beta                 90.223(8)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   8.0781(10)
_cell_length_b                   4.7930(6)
_cell_length_c                   18.345(2)
_cell_measurement_reflns_used    322
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      35.462
_cell_measurement_theta_min      4.821
_cell_volume                     710.28(15)
_computing_structure_refinement  'SHELXL-2018/3 (Sheldrick, 2018)'
_computing_structure_solution    'SHELXT 2014/5 (Sheldrick, 2014)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.960
_diffrn_measured_fraction_theta_max 0.960
_diffrn_measurement_device_type  'Siemens Bruker 3-circle diffractometer'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0428
_diffrn_reflns_av_unetI/netI     0.0222
_diffrn_reflns_Laue_measured_fraction_full 0.960
_diffrn_reflns_Laue_measured_fraction_max 0.960
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       3
_diffrn_reflns_limit_k_min       -3
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            3112
_diffrn_reflns_point_group_measured_fraction_full 0.960
_diffrn_reflns_point_group_measured_fraction_max 0.960
_diffrn_reflns_theta_full        35.462
_diffrn_reflns_theta_max         35.462
_diffrn_reflns_theta_min         4.821
_exptl_absorpt_coefficient_mu    1.392
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            white
_exptl_crystal_density_diffrn    1.909
_exptl_crystal_density_meas      'about 1.83'
_exptl_crystal_density_method    'suspension in iodobenzene does not separate'
_exptl_crystal_description       'small, thin square'
_exptl_crystal_F_000             420
_exptl_crystal_recrystallization_method 'Recrystallisation from NaOH/HCl'
_exptl_crystal_size_max          0.020
_exptl_crystal_size_mid          0.015
_exptl_crystal_size_min          0.002
_refine_diff_density_max         0.529
_refine_diff_density_min         -0.591
_refine_diff_density_rms         0.170
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   2.411
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     57
_refine_ls_number_reflns         309
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      2.411
_refine_ls_R_factor_all          0.1461
_refine_ls_R_factor_gt           0.1413
_refine_ls_shift/su_max          0.010
_refine_ls_shift/su_mean         0.003
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.2000P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.4417
_refine_ls_wR_factor_ref         0.4451
_reflns_Friedel_coverage         0.000
_reflns_number_gt                288
_reflns_number_total             322
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            lt5058.cif
_cod_data_source_block           Leuco
_cod_original_sg_symbol_H-M      'P 2/c'
_cod_database_code               1569410
_shelx_shelxl_version_number     2018/3
_shelx_res_checksum              93032
_shelx_hkl_checksum              58250