Synergistic n → π* and n<sub>N</sub> → π*<sub>Ar</sub> interactions in C-terminal modified prolines: effect on Xaa-Pro <i>cis</i>/<i>trans</i> equilibrium.
Deka, Jugal Kishore Rai; Borah, Debashree; Das, Paramesh; Sahariah, Biswajit; Vishnoi, Pratap; Sarma, Bani Kanta; Chemical communications (Cambridge, England) 59 (2023) 6080–6083; doi:10.1039/d3cc01494k

data_7131583
_publ_section_title
;
 Synergistic n &#x2192; &#x3c0;* and n<sub>N</sub> &#x2192;
 &#x3c0;*<sub>Ar</sub> interactions in C-terminal modified prolines:
 effect on Xaa-Pro <i>cis</i>/<i>trans</i> equilibrium.
;
_journal_issue                   40
_journal_name_full               'Chemical communications (Cambridge, England)'
_journal_page_first              6080
_journal_page_last               6083
_journal_paper_doi               10.1039/d3cc01494k
_journal_volume                  59
_journal_year                    2023
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C16 H21 N3 O4, 2(H2 O)'
_chemical_formula_sum            'C16 H25 N3 O6'
_chemical_formula_weight         355.39
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     iterative
_audit_creation_date             2023-02-08
_audit_creation_method
;
Olex2 1.5
(compiled 2022.04.07 svn.rca3783a0 for OlexSys, GUI svn.r6498)
;
_audit_update_record
;
2023-02-08 deposited with the CCDC.	2023-04-20 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 106.122(4)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   9.5736(9)
_cell_length_b                   8.7880(7)
_cell_length_c                   11.6294(11)
_cell_measurement_reflns_used    5334
_cell_measurement_temperature    299(2)
_cell_measurement_theta_max      27.84
_cell_measurement_theta_min      2.21
_cell_volume                     939.94(15)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'olex2.refine 1.5 (Bourhis et al., 2015)'
_computing_structure_solution    'olex2.solve 1.5 (Bourhis et al., 2015)'
_diffrn_ambient_temperature      298.74
_diffrn_measured_fraction_theta_full 0.992
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0299
_diffrn_reflns_av_unetI/netI     0.0360
_diffrn_reflns_Laue_measured_fraction_full 0.992
_diffrn_reflns_Laue_measured_fraction_max 0.994
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            16661
_diffrn_reflns_point_group_measured_fraction_full 0.993
_diffrn_reflns_point_group_measured_fraction_max 0.988
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         30.513
_diffrn_reflns_theta_min         2.214
_diffrn_source                   x-ray
_exptl_absorpt_coefficient_mu    0.096
_exptl_absorpt_correction_T_max  0.7461
_exptl_absorpt_correction_T_min  0.6748
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            silver
_exptl_crystal_density_diffrn    1.256
_exptl_crystal_description       Plate
_exptl_crystal_F_000             380
_exptl_crystal_size_max          0.3
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.118
_refine_diff_density_min         -0.107
_refine_diff_density_rms         0.024
_refine_ls_abs_structure_details
;
 Flack x determined using 1330 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.1(4)
_refine_ls_extinction_coef       0.062(12)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2018/3 (Sheldrick 2018)'
_refine_ls_goodness_of_fit_ref   1.021
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     250
_refine_ls_number_reflns         5688
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.021
_refine_ls_R_factor_all          0.0763
_refine_ls_R_factor_gt           0.0393
_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^)+(0.0412P)^2^+0.0625P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0867
_refine_ls_wR_factor_ref         0.1053
_reflns_Friedel_coverage         0.877
_reflns_Friedel_fraction_full    0.994
_reflns_Friedel_fraction_max     0.982
_reflns_number_gt                3717
_reflns_number_total             5688
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d3cc01494k2.cif
_cod_data_source_block           pro-c(o)-nh_nme-c(o)phOMe_a
_cod_depositor_comments
'Adding full bibliography for 7131582--7131585.cif.'
_cod_database_code               7131583
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_max   0.995
_shelx_estimated_absorpt_t_min   0.972
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C6(H6)
2.b Secondary CH2 refined with riding coordinates:
 C5(H5a,H5b), C4(H4a,H4b), C3(H3a,H3b)
2.c Aromatic/amide H refined with riding coordinates:
 C14(H14), C15(H15), C11(H11), C12(H12)
2.d Idealised Me refined as rotating group:
 C8(H8a,H8b,H8c), C1(H1a,H1b,H1c), C16(H16a,H16b,H16c)
;
_shelx_res_checksum              9157
_shelx_hkl_checksum              12741
_olex2_submission_special_instructions 'No special instructions were received'