Adding a Second Quinol to a Redox-Responsive MRI Contrast Agent Improves Its Relaxivity Response to H2O2.
Yu, Meng; Ward, Meghan B.; Franke, Alicja; Ambrose, Stephen L.; Whaley, Zachary L.; Bradford, Thomas Miller; Gorden, John D.; Beyers, Ronald J.; Cattley, Russell C.; Ivanović-Burmazović, Ivana; Schwartz, Dean D.; Goldsmith, Christian R.; Inorganic chemistry 56 (2017) 2812–2826; doi:10.1021/acs.inorgchem.6b02964

data_4345201
_publ_section_title
;
 Adding a Second Quinol to a Redox-Responsive MRI Contrast Agent Improves
 Its Relaxivity Response to H2O2.
;
_journal_issue                   5
_journal_name_full               'Inorganic chemistry'
_journal_page_first              2812
_journal_page_last               2826
_journal_paper_doi               10.1021/acs.inorgchem.6b02964
_journal_volume                  56
_journal_year                    2017
_chemical_formula_moiety         'C28 H28 Br2 Mn N4 O4, (H2O) (C2H3N)'
_chemical_formula_sum            'C30 H33 Br2 Mn N5 O5'
_chemical_formula_weight         758.35
_chemical_name_common            '[Mn(H4qtp2)Br2]'
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2yn'
_space_group_name_H-M_alt        'P 1 21/n 1'
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90
_cell_angle_beta                 99.8810(10)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   9.6411(2)
_cell_length_b                   21.9027(6)
_cell_length_c                   15.3507(4)
_cell_measurement_reflns_used    8877
_cell_measurement_temperature    180.(2)
_cell_measurement_theta_max      20.6360
_cell_measurement_theta_min      2.2961
_cell_volume                     3193.46(14)
_computing_cell_refinement       'SAINT V8.18C (Bruker AXS Inc., 2011)'
_computing_data_reduction        'SAINT V8.18C (Bruker AXS Inc., 2011)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      180.(2)
_diffrn_detector_area_resol_mean 8.3333
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0412
_diffrn_reflns_av_sigmaI/netI    0.0247
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       21
_diffrn_reflns_limit_k_min       -21
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            31999
_diffrn_reflns_theta_full        20.84
_diffrn_reflns_theta_max         20.84
_diffrn_reflns_theta_min         1.64
_diffrn_source                   'fine-focus sealed tube'
_exptl_absorpt_coefficient_mu    2.961
_exptl_absorpt_correction_T_max  0.943
_exptl_absorpt_correction_T_min  0.560
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS V2008/1 (Bruker AXS Inc.)'
_exptl_crystal_colour            'clear light orange'
_exptl_crystal_density_diffrn    1.577
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       Fragment
_exptl_crystal_F_000             1532.0
_exptl_crystal_size_max          0.200
_exptl_crystal_size_mid          0.200
_exptl_crystal_size_min          0.020
_platon_squeeze_details
;

Although there were four peaks within the Fourier diffference map,

the highly disordered solvents within the void were not crystallography

well defined.

The SQUEEZE routine of the program PLATON was used in order to 

eliminate the contribution of disordered solvent molecules,

thereby a final model based only on the ordered part of the crtystal

structure was obtained

The SQUEEZE routine routine suggested that a total potential solvent area 

volume of 566.2 Ang^3 [17.7% of cell volume], and a void electron population

of 146 per cell.Experimental evidence suggests the presence of 1 molecule of

acetonitrile and one water per asymetric unit.

Refinement after the SQUEEZE routine gave significantly improved R values.

[R values before SQUEEZE]

R1 = 0.0864 for >2sigma(I) data

R1 = 0.0864, wR2 = 0.2175, GOOF = S = 1.165 for all data

(4381 data and 0 restraint/ 397 parameters

,

;
_refine_diff_density_max         0.429
_refine_diff_density_min         -0.719
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.178
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     358
_refine_ls_number_reflns         3364
_refine_ls_number_restraints     12
_refine_ls_restrained_S_all      1.176
_refine_ls_R_factor_all          0.0646
_refine_ls_R_factor_gt           0.0566
_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^)+(0.0188P)^2^+16.3405P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1071
_refine_ls_wR_factor_ref         0.1104
_reflns_number_gt                3031
_reflns_number_total             3364
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ic6b02964_si_002.cif
_cod_data_source_block           '[Mn(H4qtp2)Br2]'
_cod_depositor_comments
'Adding full bibliography for 4345200--4345202.cif.'
_cod_database_code               4345201