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_1506223
_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         'C22 H14 O2'
_chemical_formula_sum            'C22 H14 O2'
_chemical_formula_weight         310.33
_chemical_melting_point          260
_chemical_name_systematic
;
 4-methyl-pyran-2-one annulated tetrahelicenes RI-2
;
_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                90.000(5)
_cell_angle_beta                 111.659(5)
_cell_angle_gamma                90.000(5)
_cell_formula_units_Z            4
_cell_length_a                   7.885(5)
_cell_length_b                   26.061(5)
_cell_length_c                   7.474(5)
_cell_measurement_reflns_used    165
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25
_cell_measurement_theta_min      2.5
_cell_volume                     1427.4(13)
_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 0.984
_diffrn_measured_fraction_theta_max 0.984
_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     0.71069
_diffrn_reflns_av_R_equivalents  0.0436
_diffrn_reflns_av_sigmaI/netI    0.0578
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       34
_diffrn_reflns_limit_k_min       -33
_diffrn_reflns_limit_l_max       9
_diffrn_reflns_limit_l_min       -9
_diffrn_reflns_number            9402
_diffrn_reflns_theta_full        28.28
_diffrn_reflns_theta_max         28.28
_diffrn_reflns_theta_min         2.78
_exptl_absorpt_coefficient_mu    0.092
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.444
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needles
_exptl_crystal_F_000             648
_exptl_crystal_recrystallization_method layering
_exptl_crystal_size_max          0.092
_exptl_crystal_size_mid          0.086
_exptl_crystal_size_min          0.078
_refine_diff_density_max         0.618
_refine_diff_density_min         -0.764
_refine_diff_density_rms         0.102
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.229
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     217
_refine_ls_number_reflns         3493
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.229
_refine_ls_R_factor_all          0.1068
_refine_ls_R_factor_gt           0.0753
_refine_ls_shift/su_max          0.013
_refine_ls_shift/su_mean         0.003
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0754P)^2^+2.1554P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1771
_refine_ls_wR_factor_ref         0.2238
_reflns_number_gt                2549
_reflns_number_total             3493
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol0619260si20060904_021321.cif
_cod_data_source_block           4
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               1506223