Two-dimensional Lead-Free Double Perovskite Ferroelastic with Dynamic Thermochromism
Su, Chang-Yuan; Yi, Heng-Guan; Ni, Hao-Fei; Du, Guowei; Xia, San-Qiang; Liu, Zunqi; Zhang, Zhi-Xu; Fu, Da-Wei; Chemical Science  (2025) –; doi:10.1039/D5SC05158D

data_1576184
_publ_section_title
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 Two-dimensional Lead-Free Double Perovskite Ferroelastic with Dynamic
 Thermochromism
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_journal_name_full               'Chemical Science'
_journal_paper_doi               10.1039/D5SC05158D
_journal_year                    2025
_chemical_formula_moiety         'Br8 Pb2, 4(C5 N)'
_chemical_formula_sum            'C20 Br8 N4 Pb2'
_chemical_formula_weight         1349.90
_space_group_crystal_system      orthorhombic
_space_group_IT_number           64
_space_group_name_Hall           '-C 2ac 2'
_space_group_name_H-M_alt        'C m c e'
_audit_creation_date             2023-07-24
_audit_creation_method
;
Olex2 1.5
(compiled 2023.03.06 svn.rbb2c1857 for OlexSys, GUI svn.r6748)
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_audit_update_record
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2023-09-04 deposited with the CCDC.	2025-10-27 downloaded from the CCDC.
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_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   29.24(3)
_cell_length_b                   8.247(6)
_cell_length_c                   8.249(6)
_cell_measurement_reflns_used    2447
_cell_measurement_temperature    388.00
_cell_measurement_theta_max      29.04
_cell_measurement_theta_min      2.77
_cell_volume                     1989(3)
_computing_cell_refinement       'SAINT V8.40B (?, 2016)'
_computing_data_reduction        'SAINT V8.40B (?, 2016)'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'XL  (Sheldrick, 2008)'
_diffrn_ambient_temperature      388.00
_diffrn_measured_fraction_theta_full 0.991
_diffrn_measured_fraction_theta_max 0.993
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0808
_diffrn_reflns_av_unetI/netI     0.0599
_diffrn_reflns_Laue_measured_fraction_full 0.991
_diffrn_reflns_Laue_measured_fraction_max 0.993
_diffrn_reflns_limit_h_max       35
_diffrn_reflns_limit_h_min       -40
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            8999
_diffrn_reflns_point_group_measured_fraction_full 0.991
_diffrn_reflns_point_group_measured_fraction_max 0.993
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.186
_diffrn_reflns_theta_min         2.786
_diffrn_source_current           1.4
_diffrn_source_power             0.07
_diffrn_source_voltage           50.0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    16.500
_exptl_absorpt_correction_T_max  0.7458
_exptl_absorpt_correction_T_min  0.3707
_exptl_absorpt_correction_type   none
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.1669 before and 0.0681 after correction.
The Ratio of minimum to maximum transmission is 0.4971.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    2.254
_exptl_crystal_description       block
_exptl_crystal_F_000             1184
_refine_diff_density_max         0.894
_refine_diff_density_min         -1.504
_refine_diff_density_rms         0.276
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.127
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     57
_refine_ls_number_reflns         1371
_refine_ls_number_restraints     8
_refine_ls_restrained_S_all      1.126
_refine_ls_R_factor_all          0.0819
_refine_ls_R_factor_gt           0.0457
_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^)+(0.0450P)^2^+1.3982P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1053
_refine_ls_wR_factor_ref         0.1190
_reflns_Friedel_coverage         0.000
_reflns_number_gt                855
_reflns_number_total             1371
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5sc05158d4.cif
_cod_data_source_block           mo_scy_cba_pbbr_388k_0m_c
_cod_original_sg_symbol_Hall     '-C 2bc 2'
_cod_database_code               1576184
_shelx_shelxl_version_number     2019/1
_olex2_refinement_description
;
1. Restrained distances
 C6-C3
 1.52 with sigma of 0.001
 C4_$1-C3 = C4-C3 = C4-C3 = C4-C3_$1
 1.52 with sigma of 0.001
 C4_$1-C2 = C4-C2
 1.52 with sigma of 0.001
 C3-C2
 2.4 with sigma of 0.04
2. Others
 Fixed Sof: N1(0.5) C6(0.5) C4(0.5)
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_shelx_res_checksum              46765
_olex2_submission_special_instructions 'No special instructions were received'