Photodimerisation of the α′-polymorph of ortho-ethoxy-trans-cinnamic acid occurs via a two-stage mechanism at 343 K yielding 100% α-truxillic acid
Fernandes, M. A.; Levendis, D. C.; CrystEngComm 18 (2016) 7363–; doi:10.1039/C6CE00809G

data_7225842
_publ_section_title
;
 Photodimerisation of the \a&#x2032;-polymorph of
 ortho-ethoxy-trans-cinnamic acid occurs via a two-stage mechanism at 343
 K yielding 100% \a-truxillic acid
;
_journal_issue                   38
_journal_name_full               CrystEngComm
_journal_page_first              7363
_journal_paper_doi               10.1039/C6CE00809G
_journal_volume                  18
_journal_year                    2016
_chemical_formula_moiety         'C22 H24 O6, C11 H12 O3'
_chemical_formula_sum            'C33 H36 O9'
_chemical_formula_weight         576.62
_chemical_name_common
;
ortho-ethoxy-trans-cinnamic acid and 2,2'-diethoxy alpha-truxillic acid 
;
_chemical_name_systematic
'(E)-3-(2-Ethoxyphenyl)propenoic acid and trans-2,4-bis(2-ethoxyphenyl)-trans-1,3-cyclobutane-dicarboxylic acid'
_space_group_crystal_system      triclinic
_space_group_IT_number           2
_space_group_name_Hall           '-P 1'
_space_group_name_H-M_alt        'P -1'
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2016-04-08 deposited with the CCDC.
2016-07-06 downloaded from the CCDC.
;
_cell_angle_alpha                105.141(14)
_cell_angle_beta                 92.907(18)
_cell_angle_gamma                104.043(16)
_cell_formula_units_Z            2
_cell_length_a                   8.435(6)
_cell_length_b                   11.431(8)
_cell_length_c                   17.048(12)
_cell_measurement_reflns_used    241
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      17.80
_cell_measurement_theta_min      2.49
_cell_volume                     1527.8(19)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SHELXTL'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'Bruker SHELXTL'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.996
_diffrn_measured_fraction_theta_max 0.996
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.2045
_diffrn_reflns_av_unetI/netI     0.4045
_diffrn_reflns_Laue_measured_fraction_full 0.996
_diffrn_reflns_Laue_measured_fraction_max 0.996
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -4
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            5034
_diffrn_reflns_point_group_measured_fraction_full 0.996
_diffrn_reflns_point_group_measured_fraction_max 0.996
_diffrn_reflns_theta_full        19.999
_diffrn_reflns_theta_max         19.999
_diffrn_reflns_theta_min         1.247
_exptl_absorpt_coefficient_mu    0.091
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            'opaque white'
_exptl_crystal_density_diffrn    1.253
_exptl_crystal_description       needle
_exptl_crystal_F_000             612
_exptl_crystal_recrystallization_method
'Crystallised from ethyl acetate followed by photoreaction at 343 K.'
_exptl_crystal_size_max          0.640
_exptl_crystal_size_mid          0.200
_exptl_crystal_size_min          0.170
_refine_diff_density_max         0.416
_refine_diff_density_min         -0.418
_refine_diff_density_rms         0.126
_refine_ls_extinction_coef       0.068(11)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2014/7 (Sheldrick 2014'
_refine_ls_goodness_of_fit_ref   0.912
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     165
_refine_ls_number_reflns         2827
_refine_ls_number_restraints     153
_refine_ls_restrained_S_all      0.907
_refine_ls_R_factor_all          0.3670
_refine_ls_R_factor_gt           0.1381
_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^)+(0.1804P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.3010
_refine_ls_wR_factor_ref         0.4215
_reflns_Friedel_coverage         0.000
_reflns_number_gt                691
_reflns_number_total             2827
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c6ce00809g2.cif
_cod_data_source_block           120h_343K
_cod_depositor_comments
'Adding full bibliography for 7225842--7225850.cif.'
_cod_database_code               7225842
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.944
_shelx_estimated_absorpt_t_max   0.985
_shelx_res_checksum              24616