Facile synthesis, fluorescence, and photochromism of novel helical pyrones and chromenes.
Moorthy, Jarugu Narasimha; Venkatakrishnan, Parthasarathy; Sengupta, Sanchita; Baidya, Mahiuddin; Organic letters 8 (2006) 4891–4894; doi:10.1021/ol0619260

data_1506220
_publ_section_title
;
 Facile synthesis, fluorescence, and photochromism of novel helical
 pyrones and chromenes.
;
_journal_issue                   21
_journal_name_full               'Organic letters'
_journal_page_first              4891
_journal_page_last               4894
_journal_paper_doi               10.1021/ol0619260
_journal_volume                  8
_journal_year                    2006
_chemical_compound_source        synthetic
_chemical_formula_moiety         'C21 H12 O2'
_chemical_formula_sum            'C21 H12 O2'
_chemical_formula_weight         296.31
_chemical_melting_point          225
_chemical_name_systematic
;
 pyran-2-one annulated tetrahelicene RI-2
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yab'
_symmetry_space_group_name_H-M   'P 1 21/a 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                 107.000(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   7.3419(7)
_cell_length_b                   24.750(2)
_cell_length_c                   7.8224(7)
_cell_measurement_reflns_used    165
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      25
_cell_measurement_theta_min      2.5
_cell_volume                     1359.3(2)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Ortep-3 for Windows (Farrugia, 1997)'
_computing_publication_material  'WinGX publication routines (Farrugia, 1999)'
_computing_structure_refinement  'Bruker SHELXTL'
_computing_structure_solution    'Bruker SHELXTL'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.989
_diffrn_measured_fraction_theta_max 0.989
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0350
_diffrn_reflns_av_sigmaI/netI    0.0404
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       26
_diffrn_reflns_limit_k_min       -33
_diffrn_reflns_limit_l_max       10
_diffrn_reflns_limit_l_min       -10
_diffrn_reflns_number            8961
_diffrn_reflns_theta_full        28.33
_diffrn_reflns_theta_max         28.33
_diffrn_reflns_theta_min         2.72
_exptl_absorpt_coefficient_mu    0.092
_exptl_absorpt_correction_T_max  0.9908
_exptl_absorpt_correction_T_min  0.9908
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.448
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plates
_exptl_crystal_F_000             616
_exptl_crystal_recrystallization_method Evaporation
_exptl_crystal_size_max          0.12
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.09
_refine_diff_density_max         0.471
_refine_diff_density_min         -0.455
_refine_diff_density_rms         0.090
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.151
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     208
_refine_ls_number_reflns         3353
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.151
_refine_ls_R_factor_all          0.0815
_refine_ls_R_factor_gt           0.0570
_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^)+(0.0388P)^2^+2.3140P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1235
_refine_ls_wR_factor_ref         0.1634
_reflns_number_gt                2650
_reflns_number_total             3353
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol0619260si20060904_021321.cif
_cod_data_source_block           2
_cod_original_sg_symbol_H-M      P21/a
_cod_database_code               1506220