Planarisation or a twist? Using steric engineering to unlock the origin of mechanofluorochromic red-shifts.
McDonald, Peter W.; Goerigk, Lars; Ritchie, Chris; Chemical science 16 (2025) 15320–15332; doi:10.1039/d5sc04257g

data_1575172
_publ_section_title
;
 Planarisation or a twist? Using steric engineering to unlock the origin
 of mechanofluorochromic red-shifts.
;
_journal_issue                   34
_journal_name_full               'Chemical science'
_journal_page_first              15320
_journal_page_last               15332
_journal_paper_doi               10.1039/d5sc04257g
_journal_volume                  16
_journal_year                    2025
_chemical_formula_moiety         'C18 H16 N2'
_chemical_formula_sum            'C18 H16 N2'
_chemical_formula_weight         260.33
_chemical_name_systematic        3-methyl-N,N-diphenylpyridin-4-amine
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2025-05-25
_audit_creation_method
;
Olex2 1.5
(compiled 2025.04.05 svn.rf049d14d for OlexSys, GUI svn.r7224)
;
_audit_update_record
;
2025-06-06 deposited with the CCDC.	2025-07-18 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 92.658(2)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.1945(2)
_cell_length_b                   16.3667(3)
_cell_length_c                   10.3703(2)
_cell_measurement_reflns_used    8437
_cell_measurement_temperature    122.99(10)
_cell_measurement_theta_max      79.2840
_cell_measurement_theta_min      5.0210
_cell_volume                     1389.34(5)
_computing_cell_refinement       'CrysAlisPro 1.171.41.113a (Rigaku OD, 2021)'
_computing_data_collection       'CrysAlisPro 1.171.41.113a (Rigaku OD, 2021)'
_computing_data_reduction        'CrysAlisPro 1.171.41.113a (Rigaku OD, 2021)'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2019/3 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      122.99(10)
_diffrn_detector                 'Hybrid Pixel Array Detector'
_diffrn_detector_area_resol_mean 10.0000
_diffrn_detector_type            HyPix
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 0.979
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w    101.00 178.00   0.50    0.82    --  113.25  45.00-120.00  154
  2  \w     95.00 178.00   0.50    0.82    --  113.25 125.00  30.00  166
  3  \w    101.00 178.00   0.50    0.82    --  113.25  46.00 124.00  154
  4  \w     35.00 120.00   0.50    0.21    --   47.88  46.00 124.00  170
  5  \w    -60.00  25.00   0.50    0.21    --  -47.88  46.00 124.00  170
  6  \w    -79.00 -19.00   0.50    0.82    --  -91.75  46.00 124.00  120
  7  \w    -78.00 -20.00   0.50    0.82    --  -91.75  45.00 -60.00  116
  8  \w   -163.00 -79.00   0.50    0.82    --  -91.75 -46.00 -24.00  168
  9  \w   -119.00 -35.00   0.50    0.21    --  -47.88 -46.00 -24.00  168
 10  \w     82.00 108.00   0.50    0.82    --  113.25 -61.00-180.00   52
 11  \w    -23.00  61.00   0.50    0.21    --   47.88 -46.00 -24.00  168
 12  \w     42.00  76.00   0.50    0.82    --  113.25 -45.00 -60.00   68
 13  \w     42.00  77.00   0.50    0.82    --  113.25 -46.00 -24.00   70
 14  \w     42.00  76.00   0.50    0.82    --  113.25 -45.00   0.00   68
 15  \w     39.00  66.00   0.50    0.82    --  113.25 -30.00 -90.00   54
 16  \w     42.00  67.00   0.50    0.82    --  113.25 -45.00  30.00   50
 17  \w     42.00  76.00   0.50    0.82    --  113.25 -45.00  90.00   68
 18  \w     42.00  76.00   0.50    0.82    --  113.25 -45.00 150.00   68
 19  \w     39.00  66.00   0.50    0.82    --  113.25 -30.00 120.00   54
 20  \w     42.00  76.00   0.50    0.82    --  113.25 -45.00 120.00   68
 21  \w     39.00  64.00   0.50    0.82    --  113.25 -30.00  90.00   50
 22  \w     39.00 127.00   0.50    0.82    --  113.25 -15.00 120.00  176
 23  \w     39.00  66.00   0.50    0.82    --  113.25 -30.00  30.00   54
 24  \w     39.00  66.00   0.50    0.82    --  113.25 -30.00   0.00   54
 25  \w     39.00  66.00   0.50    0.82    --  113.25 -30.00-180.00   54
 26  \w     34.00  96.00   0.50    0.21    --   47.88-125.00-180.00  124
 27  \w     34.00  96.00   0.50    0.21    --   47.88-125.00 -30.00  124
 28  \w     42.00 111.00   0.50    0.82    --  113.25-125.00 -60.00  138
 29  \w     42.00 106.00   0.50    0.82    --  113.25 -94.00   0.00  128
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'XtaLAB Synergy, Dualflex, HyPix'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      -0.1591086000
_diffrn_orient_matrix_UB_12      0.0341991000
_diffrn_orient_matrix_UB_13      -0.0640164000
_diffrn_orient_matrix_UB_21      0.0991093000
_diffrn_orient_matrix_UB_22      0.0418387000
_diffrn_orient_matrix_UB_23      -0.1040948000
_diffrn_orient_matrix_UB_31      -0.0168200000
_diffrn_orient_matrix_UB_32      -0.0770311000
_diffrn_orient_matrix_UB_33      -0.0848336000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           'Cu K\a'
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0407
_diffrn_reflns_av_unetI/netI     0.0346
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 0.979
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       19
_diffrn_reflns_limit_k_min       -20
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            13964
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 0.979
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         79.608
_diffrn_reflns_theta_min         5.053
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'PhotonJet (Cu) X-ray Source'
_exptl_absorpt_coefficient_mu    0.569
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.12501
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.41.113a (Rigaku Oxford Diffraction, 2021)
Empirical absorption correction using spherical harmonics,
implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            'clear colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.245
_exptl_crystal_description       irregular
_exptl_crystal_F_000             552
_exptl_crystal_preparation       oil
_exptl_crystal_recrystallization_method 'ethyl acetate'
_exptl_crystal_size_max          0.4
_exptl_crystal_size_mid          0.08
_exptl_crystal_size_min          0.01
_refine_diff_density_max         0.279
_refine_diff_density_min         -0.273
_refine_diff_density_rms         0.043
_refine_ls_extinction_coef       0.0015(5)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2019/2 (Sheldrick 2019)'
_refine_ls_goodness_of_fit_ref   1.077
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     183
_refine_ls_number_reflns         2963
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.077
_refine_ls_R_factor_all          0.0493
_refine_ls_R_factor_gt           0.0445
_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^)+(0.0574P)^2^+0.4757P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1175
_refine_ls_wR_factor_ref         0.1218
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2626
_reflns_number_total             2963
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5sc04257g2.cif
_cod_data_source_block           pm2_162col1v7a_auto
_cod_depositor_comments
'Adding full bibliography for 1575172--1575185.cif.'
_cod_database_code               1575172
_shelx_shelxl_version_number     2019/3
_chemical_oxdiff_formula         C20H16N2
_shelx_estimated_absorpt_t_max   0.994
_shelx_estimated_absorpt_t_min   0.805
_diffrn_oxdiff_digest_hkl
;
017a4713768f96944bdb648b9273c1534bc5b9
;
_reflns_odcompleteness_completeness 99.89
_reflns_odcompleteness_iscentric 1
_reflns_odcompleteness_theta     71.98
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Aromatic/amide H refined with riding coordinates:
 C8(H8), C4(H4), C12(H12), C9(H9), C2(H2), C5(H5), C10(H10), C11(H11),
 C17(H17), C1(H1), C6(H6), C15(H15), C16(H16)
2.b Idealised Me refined as rotating group:
 C18(H18A,H18B,H18C)
;
_shelx_res_checksum              5446
_olex2_exptl_crystal_mounting_method oil
_olex2_submission_original_sample_id '3 123 K'
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 4.119
_oxdiff_exptl_absorpt_empirical_full_min 0.448