Research ArticleChemistry

π-π stacking interactions: Non-negligible forces for stabilizing porous supramolecular frameworks

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Science Advances  10 Jan 2020:
Vol. 6, no. 2, eaax9976
DOI: 10.1126/sciadv.aax9976
  • Fig. 1 Crystal structures of π-1.

    (A) Mononuclear Zn(II) structural unit in π-1. (B) The building block of π-1 viewed along the b axis, showing the strong π-π stacking interactions between phen rings. The selected distances (D) between ring centroids are as follows: DCg2-Cg5 = 3.476(5) Å, DCg3-Cg6 = 3.753(7) Å, DCg6-Cg6 = 3.577(7) Å, and DCg6-Cg10 = 3.465(6) Å. (C) π-π stacking interactions between building blocks. The selected distances (D) between ring centroids are as follows: DCg1-Cg3 = 3.621(6) Å, DCg1-Cg5 = 3.645(5) Å, DCg1-Cg10 = 3.710(6) Å, DCg4-Cg6 = 3.753(7) Å, and DCg4-Cg9 = 3.577(7) Å. (D) 3D porous supramolecular structure of π-1 viewed along the c axis, where one building block (yellow) surrounded by four other building blocks (blue and purple) is clearly demonstrated.

  • Fig. 2 Adsorption results of π-1 to Hg2+.

    (A) Adsorption capacity of π-1 to Hg2+ at different initial concentrations. (B) Adsorption process of π-1 to Hg2+ at an initial concentration of 100 mg/liter. (C) Plot of t/qt versus t. (D) Adsorption ratio of π-1 to metal ions in a mixed solution containing Hg2+, Pb2+, Cd2+, Cu2+, Zn2+, Ca2+, and Mg2+, with respective initial concentrations of 100 mg/liter.

  • Table 1 π-π stacking interactions in π-1.

    Cg1, N1 → N2 → N3 → N4 → C8→; Cg2, N6 → C18 → C17 → C16 → C15 → C19→; Cg3, N8 → C30 → C29 → C28 → C27 → C31→; Cg4, C2 → C3 → C4 → C5 → C6 → C7→; Cg5, C12 → C13 → C14 → C15 → C19 → C20→; Cg6, C24 → C25 → C26 → C27 → C31 → C32→; Cg7, N5 → C9 → C10 → C11 → C12 → C13 → C14 → C15 → C19 → C20→; Cg8, N6 → C18 → C17 → C16 → C15 → C14 → C13 → C12 → C20 → C19→; Cg9, N7 → C21 → C22 → C23 → C24 → C25 → C26 → C27 → C31 → C32→; Cg10, N8 → C30 → C29 → C28 → C27 → C26 → C25 → C24 → C32 → C31→; Cg11, N5 → C9 → C10 → C11 → C12 → C13 → C14 → C15 → C16 → C17 → C18 → N6 → C19 → C20→; Cg12, N7 → C21 → C22 → C23 → C24 → C25 → C26 → C27 → C28 → C29 → C30 → N8 → C31 → C32→.

    Entryπ-π interactionsCg-Cg (Å)*α (°)β (°)Cg-plane (Å)§Slippage (Å)||Symmetry operation on Cg
    1Cg1-Cg33.621(6)0.0(5)22.93.335(3)1.410xy, −1 + x, 2 − z
    2Cg1-Cg53.645(5)0.0(4)25.33.015(8)/3.295(3)1.5571/3 + y, 2/3 – x + y, 5/3 − z
    3Cg1-Cg103.710(6)0.0(4)25.83.340(3)1.615xy, −1 + x, 2 − z
    4Cg2-Cg53.475(5)0.6(4)8.83.434(3)0.5345/3 − x, 1/3 − y, 4/3 − z
    5Cg2-Cg73.784(5)1.1(3)25.53.432(3)/3.415(3)1.6295/3 − x, 1/3 − y, 4/3 − z
    6Cg2-Cg83.721(5)0.3(3)22.43.434(3)/3.440(2)1.4175/3 − x, 1/3 − y, 4/3 − z
    7Cg2-Cg113.700(4)0.7(3)22.23.427(3)3.425(2)1.3995/3 − x, 1/3 − y, 4/3 − z
    8Cg3-Cg63.753(7)1.4(6)24.43.388(5)/3.419(5)1.5475/3 − x, 1/3 − y, 7/3 − z
    9Cg3-Cg93.866(6)2.2(5)29.03.373(5)/3.380(4)1.8775/3 − x, 1/3 − y, 7/3 − z
    10Cg4-Cg63.920(6)0.0(5)24.93.557(3)1.648xy, −1 + x, 2 − z
    11Cg4-Cg93.914(5)0.0(3)23.93.578(3)1.587xy, −1 + x, 2 − z
    12Cg5-Cg23.476(5)0.6(4)8.93.434(3)0.5365/3 − x, 1/3 − y, 4/3 − z
    13Cg5-Cg83.627(4)0.3(3)18.63.433(2)/3.438(2)1.1545/3 − x, 1/3 − y, 4/3 − z
    14Cg6-Cg33.753(7)1.4(6)25.53.419(5)/3.387(5)1.6165/3 − x, 1/3 − y, 7/3 − z
    15Cg6-Cg63.577(7)0.0(6)17.73.408(5)1.0875/3 − x, 1/3 − y, 7/3 − z
    16Cg6-Cg103.465(6)0.6(5)11.53.398(5)/3.395(4)0.6895/3 − x, 1/3 − y, 7/3 − z
    17Cg6-Cg123.674(6)0.6(5)22.93.397(5)/3.383(3)1.4315/3 − x, 1/3 − y, 7/3 − z
    18Cg7-Cg23.784(5)1.1(3)24.93.416(3)/3.432(3)1.5945/3 − x, 1/3 − y, 4/3 − z
    19Cg8-Cg23.721(5)0.3(3)22.73.441(2)/3.434(3)1.4335/3 − x, 1/3 − y, 4/3 − z
    20Cg8-Cg53.627(4)0.3(3)18.83.438(2)/3.433(3)1.1695/3 − x, 1/3 − y, 4/3 − z
    21Cg8-Cg83.476(4)0.0(2)9.03.433(2)0.5425/3 − x, 1/3 − y, 4/3 − z
    22Cg8-Cg113.700(4)0.4(2)22.33.432(2)/3.423(2)1.4055/3 − x, 1/3 − y, 4/3 − z
    23Cg9-Cg33.866(6)2.2(5)29.23.380(4)/3.373(5)1.8895/3 − x, 1/3 − y, 7/3 − z
    24Cg9-Cg103.768(5)1.4(4)25.73.369(4)/3.394(4)1.6375/3 − x, 1/3 − y, 7/3 − z
    25Cg10-Cg63.464(6)0.6(5)11.33.395(4)/3.397(5)0.6785/3 − x, 1/3 − y, 7/3 − z
    26Cg10-Cg93.768(5)1.4(4)26.63.394(4)/3.369(4)1.6895/3 − x, 1/3 − y, 7/3 − z
    27Cg10-Cg103.749(5)0.0(4)25.13.396(4)/3.396(4)1.5885/3 − x, 1/3 − y, 7/3 − z
    28Cg10-Cg123.714(5)0.8(3)24.73.386(4)/3.376(3)1.5495/3 − x, 1/3 − y, 7/3 − z
    29Cg11-Cg23.701(4)0.7(3)22.23.426(2)/3.427(3)1.3965/3 − x, 1/3 − y, 4/3 − z
    30Cg11-Cg83.700(4)0.4(2)22.03.423(2)/3.432(2)1.3835/3 − x, 1/3 − y, 4/3 − z
    31Cg12-Cg63.673(6)0.6(5)22.43.383(3)/3.396(5)1.3985/3 − x, 1/3 − y, 7/3 − z
    32Cg12-Cg103.714(5)0.8(3)24.33.376(3)/3.386(4)1.5275/3 − x, 1/3 − y, 7/3 − z
    33Cg12-Cg123.965(4)0.0(2)31.53.380(3)/3.381(3)2.0725/3 − x, 1/3 − y, 7/3 − z

    *Distance between ring centroids.

    †Dihedral angle between planes I and J.

    ‡Angle between Cg(I)-Cg(J) vector and normal to plane I.

    §Perpendicular distance of Cg(I) on ring J.

    ||Distance between Cg(I) and perpendicular projection of Cg(J) on ring I.

    Supplementary Materials

    • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/2/eaax9976/DC1

      Supplementary Methods

      Table S1. Crystal data and structure refinements for π-1.

      Table S2. Selected bond length (Å) and angle (°) for π-1.

      Fig. S1. Morphology and composition characterization of π-1.

      Fig. S2. 3D porous supramolecular structures of π-1 viewed along the c axis.

      Fig. S3. π-π stacking interactions and corresponding distances (D) between ring centroids in π-1.

      Fig. S4. Thermal stability of π-1.

      Fig. S5. Chemical stability of π-1.

      Fig. S6. Repeated experiments of π-1 for adsorbing Hg2+.

      Fig. S7. Repeated experiments of π-1 for selectively capturing Hg2+.

      Fig. S8. The durability of π-1 during Hg2+ adsorption.

    • Supplementary Materials

      This PDF file includes:

      • Supplementary Methods
      • Table S1. Crystal data and structure refinements for π-1.
      • Table S2. Selected bond length (Å) and angle (°) for π-1.
      • Fig. S1. Morphology and composition characterization of π-1.
      • Fig. S2. 3D porous supramolecular structures of π-1 viewed along the c axis.
      • Fig. S3. π-π stacking interactions and corresponding distances (D) between ring centroids in π-1.
      • Fig. S4. Thermal stability of π-1.
      • Fig. S5. Chemical stability of π-1.
      • Fig. S6. Repeated experiments of π-1 for adsorbing Hg2+.
      • Fig. S7. Repeated experiments of π-1 for selectively capturing Hg2+.
      • Fig. S8. The durability of π-1 during Hg2+ adsorption.

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