Exciton interactions in helical crystals of a hydrogen-bonded eumelanin monomer
Sasikumar, Devika; Vinod, Kavya; Sunny, Jeswin; Hariharan, Mahesh; Chemical Science 13 (2022) 2331–2338; doi:10.1039/D1SC06755A

data_1566188
_publ_section_title
;
 Exciton interactions in helical crystals of a hydrogen-bonded eumelanin
 monomer
;
_journal_issue                   8
_journal_name_full               'Chemical Science'
_journal_page_first              2331
_journal_page_last               2338
_journal_paper_doi               10.1039/D1SC06755A
_journal_volume                  13
_journal_year                    2022
_chemical_formula_sum            'C8 H7 N O2'
_chemical_formula_weight         149.15
_chemical_properties_physical    Air-sensitive,Moisture-sensitive
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2018/3
_audit_update_record
;
2021-11-08 deposited with the CCDC.	2022-01-27 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   5.862(3)
_cell_length_b                   7.712(4)
_cell_length_c                   14.907(8)
_cell_measurement_temperature    296(2)
_cell_volume                     673.9(6)
_computing_structure_refinement  'SHELXL-2018/3 (Sheldrick, 2018)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0547
_diffrn_reflns_av_unetI/netI     0.0475
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -9
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -17
_diffrn_reflns_number            5841
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        24.995
_diffrn_reflns_theta_max         24.995
_diffrn_reflns_theta_min         2.733
_exptl_absorpt_coefficient_mu    0.107
_exptl_crystal_density_diffrn    1.470
_exptl_crystal_F_000             312
_exptl_crystal_size_max          0.150
_exptl_crystal_size_mid          0.095
_exptl_crystal_size_min          0.048
_refine_diff_density_max         0.152
_refine_diff_density_min         -0.140
_refine_diff_density_rms         0.035
_refine_ls_abs_structure_details
;
 Flack x determined using 279 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -2.3(10)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.023
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     102
_refine_ls_number_reflns         1183
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.023
_refine_ls_R_factor_all          0.0689
_refine_ls_R_factor_gt           0.0471
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0503P)^2^+0.1300P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1044
_refine_ls_wR_factor_ref         0.1155
_reflns_Friedel_coverage         0.645
_reflns_Friedel_fraction_full    1.000
_reflns_Friedel_fraction_max     1.000
_reflns_number_gt                902
_reflns_number_total             1183
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d1sc06755a2.cif
_cod_data_source_block           shelx
_cod_depositor_comments          'Adding full bibliography for 1566188.cif.'
_cod_original_cell_volume        674.0(6)
_cod_database_code               1566188
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_min   0.984
_shelx_estimated_absorpt_t_max   0.995
_shelx_res_checksum              54169
_shelx_hkl_checksum              73914