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_1518514
_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            'C25 H18 N2 O2'
_chemical_formula_weight         378.41
_chemical_name_common            TriboII
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 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                 105.530(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   14.38400(10)
_cell_length_b                   8.2140(5)
_cell_length_c                   17.3650(9)
_cell_measurement_temperature    293(2)
_cell_volume                     1976.77(16)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.987
_diffrn_measured_fraction_theta_max 0.987
_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
_diffrn_reflns_av_R_equivalents  0.0515
_diffrn_reflns_av_sigmaI/netI    0.2327
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            9519
_diffrn_reflns_theta_full        27.50
_diffrn_reflns_theta_max         27.50
_diffrn_reflns_theta_min         2.43
_exptl_absorpt_coefficient_mu    0.082
_exptl_crystal_colour            red
_exptl_crystal_density_diffrn    1.272
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             792
_refine_diff_density_max         0.400
_refine_diff_density_min         -0.229
_refine_diff_density_rms         0.057
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.491
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     262
_refine_ls_number_reflns         4489
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.491
_refine_ls_R_factor_all          0.0804
_refine_ls_R_factor_gt           0.0410
_refine_ls_shift/su_max          0.000
_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
_refine_ls_wR_factor_gt          0.1138
_refine_ls_wR_factor_ref         0.1482
_reflns_number_gt                2126
_reflns_number_total             4489
_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            1283497142137493_add3.cif
_cod_data_source_block           raw
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to
/usr/data/users/saulius/crontab/automatic-downloads/current/BMC/lib/dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 2935 2014-11-11 08:27:57Z andrius 
;
_cod_original_sg_symbol_H-M      P2(1)/n
_cod_database_code               1518514