On Crystal versus Fiber Formation in Dipeptide Hydrogelator Systems.
Houton, Kelly A.; Morris, Kyle L.; Chen, Lin; Schmidtmann, Marc; Jones, James T. A.; Serpell, Louise C.; Lloyd, Gareth O.; Adams, Dave J.; Langmuir : the ACS journal of surfaces and colloids 28 (2012) 9797–9806; doi:10.1021/la301371q

data_4506415
_publ_section_title
;
 On Crystal versus Fiber Formation in Dipeptide Hydrogelator Systems.
;
_journal_issue                   25
_journal_name_full
'Langmuir : the ACS journal of surfaces and colloids'
_journal_page_first              9797
_journal_page_last               9806
_journal_paper_doi               10.1021/la301371q
_journal_volume                  28
_journal_year                    2012
_chemical_absolute_configuration syn
_chemical_formula_sum            'C18 H20 N2 O5'
_chemical_formula_weight         344.36
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   4.9680(6)
_cell_length_b                   9.6339(14)
_cell_length_c                   35.173(5)
_cell_measurement_reflns_used    3376
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      26.27
_cell_measurement_theta_min      2.41
_cell_volume                     1683.4(4)
_computing_cell_refinement       'Bruker AXS SAINT V7.68A'
_computing_data_collection       'CrystalClear-SM Expert 2.1 (Rigaku, 2011)'
_computing_data_reduction        'Bruker AXS SAINT V7.68A'
_computing_structure_refinement  'SHELXL (Sheldrick, 2008)'
_computing_structure_solution    'SHELXD (Sheldrick, 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_detector_area_resol_mean 28.5714
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Rigaku Saturn724+ (2x2 bin mode)'
_diffrn_measurement_method       'profile data from \w-scans'
_diffrn_radiation_monochromator  confocal
_diffrn_radiation_source         'Rotating Anode'
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0676
_diffrn_reflns_av_sigmaI/netI    0.0659
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       43
_diffrn_reflns_limit_l_min       -36
_diffrn_reflns_number            16543
_diffrn_reflns_theta_full        26.36
_diffrn_reflns_theta_max         26.36
_diffrn_reflns_theta_min         2.19
_exptl_absorpt_coefficient_mu    0.100
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.6601
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS 2008/1 (Sheldrick, 2008)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.359
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             728
_exptl_crystal_size_max          0.09
_exptl_crystal_size_mid          0.06
_exptl_crystal_size_min          0.01
_refine_diff_density_max         0.454
_refine_diff_density_min         -0.263
_refine_diff_density_rms         0.044
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   1.7(12)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.018
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     240
_refine_ls_number_reflns         3440
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.018
_refine_ls_R_factor_all          0.0676
_refine_ls_R_factor_gt           0.0436
_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^)+(0.0400P)^2^+0.1600P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0896
_refine_ls_wR_factor_ref         0.0987
_reflns_number_gt                2675
_reflns_number_total             3440
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            la301371q_si_006.cif
_cod_data_source_block           dipeptide_2
_cod_original_sg_symbol_H-M      P2(1)2(1)2(1)
_cod_database_code               4506415