A mechanophysical phase transition provides a dramatic example of colour polymorphism: the tribochromism of a substituted tri(methylene)tetrahydrofuran-2-one.
Asiri, Abdullah M.; Heller, Harry G.; Hughes, David S.; Hursthouse, Michael B.; Kendrick, John; Leusen, Frank Jj; Montis, Riccardo; Chemistry Central journal 8 (2014) 70–; doi:10.1186/s13065-014-0070-3

data_1518516
_publ_section_title
;
 A mechanophysical phase transition provides a dramatic example of colour
 polymorphism: the tribochromism of a substituted
 tri(methylene)tetrahydrofuran-2-one.
;
_journal_issue                   1
_journal_name_full               'Chemistry Central journal'
_journal_page_first              70
_journal_paper_doi               10.1186/s13065-014-0070-3
_journal_volume                  8
_journal_year                    2014
_chemical_formula_sum            'C27 H20 N2 O2'
_chemical_formula_weight         404.45
_chemical_name_common            TriboIIIb
_chemical_name_systematic
;
 ?
;
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/c 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                 99.060(18)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   20.349(2)
_cell_length_b                   10.095(2)
_cell_length_c                   21.338(2)
_cell_measurement_temperature    293(2)
_cell_volume                     4328.6(11)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.878
_diffrn_measured_fraction_theta_max 0.878
_diffrn_measurement_device_type  'FAST TV Area Detector'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'FR591 Rotating Anode'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
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_diffrn_reflns_av_sigmaI/netI    0.2364
_diffrn_reflns_limit_h_max       25
_diffrn_reflns_limit_h_min       -27
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -29
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_diffrn_reflns_theta_full        29.92
_diffrn_reflns_theta_max         29.92
_diffrn_reflns_theta_min         2.26
_exptl_absorpt_coefficient_mu    0.079
_exptl_crystal_colour            red
_exptl_crystal_density_diffrn    1.241
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             1696
_refine_diff_density_max         0.715
_refine_diff_density_min         -0.195
_refine_diff_density_rms         0.042
_refine_ls_extinction_coef       0.0147(11)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   0.594
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     282
_refine_ls_number_reflns         5498
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.594
_refine_ls_R_factor_all          0.1348
_refine_ls_R_factor_gt           0.0616
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
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_refine_ls_wR_factor_ref         0.2199
_reflns_number_gt                1708
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_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            1283497142137493_add5.cif
_cod_data_source_block           s92
_cod_original_cell_volume        4328.6(10)
_cod_original_sg_symbol_H-M      C2/c
_cod_database_code               1518516