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_1506221
_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          192
_chemical_name_systematic
;
 2-pyranone-annulated tetrahelicenes RI-1
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/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                 104.03
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   12.559(5)
_cell_length_b                   5.626(5)
_cell_length_c                   19.945(5)
_cell_measurement_reflns_used    165
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25
_cell_measurement_theta_min      2.5
_cell_volume                     1367.2(14)
_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 0.986
_diffrn_measured_fraction_theta_max 0.986
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_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  0.0745
_diffrn_reflns_av_sigmaI/netI    0.1047
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       -16
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -17
_diffrn_reflns_number            8552
_diffrn_reflns_theta_full        28.32
_diffrn_reflns_theta_max         28.32
_diffrn_reflns_theta_min         2.10
_exptl_absorpt_coefficient_mu    0.092
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.440
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prisms
_exptl_crystal_F_000             616
_exptl_crystal_recrystallization_method Evaporation
_exptl_crystal_size_max          0.1
_exptl_crystal_size_mid          0.9
_exptl_crystal_size_min          0.6
_refine_diff_density_max         0.695
_refine_diff_density_min         -0.366
_refine_diff_density_rms         0.117
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.127
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     208
_refine_ls_number_reflns         3368
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.127
_refine_ls_R_factor_all          0.1751
_refine_ls_R_factor_gt           0.1327
_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^)+(0.1355P)^2^+9.5136P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.3673
_refine_ls_wR_factor_ref         0.3935
_reflns_number_gt                2205
_reflns_number_total             3368
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol0619260si20060904_021321.cif
_cod_data_source_block           1
_cod_original_sg_symbol_H-M      P21/c
_cod_database_code               1506221