Fine Tuning the Hydrophobicity of a New Three-Dimensional Cu2+ MOF through Single Crystal Coordinating Ligand Exchange Transformations

The synthesis, characterization, and single–crystal–to–single–crystal (SCSC) exchange reactions of a new 3D Cu2+ MOF based on 5-aminoisophthalic acid (H2AIP), [Cu6(μ3-ΟΗ)3(ΑΙΡ)4(HΑΙΡ)]n·6nDMF·nH2O - UCY-16·6nDMF·nH2O, are reported. It exhibits a 3D structure based on two [Cu4(μ3–OH)2]6+ butterfly–like secondary building units, differing in their peripheral ligation, bridged through HAIP–/AIP2– ligands. This compound displays the capability to exchange the coordinating ligand(s) and/or guest solvent molecules through SCSC reactions. Interestingly, heterogeneous reactions of single crystals of UCY-16·6nDMF·nH2O with primary alcohols resulted not only in the removal of the lattice DMF molecules but also in an unprecedented structural alteration that involved the complete or partial replacement of the monoatomic bridging μ3–OH– anion(s) of the [Cu4(μ3–OH)2]6+ butterfly structural core by various alkoxy groups. Similar crystal-to-crystal exchange reactions of UCY-16·6nDMF·nH2O with long-chain aliphatic alcohols (CxH2x+1OH, x = 8–10, 12, 14, and 16) led to analogues containing fatty alcohols. Notably, the exchanged products with the bulkier alcohols UCY-16/n-CxH2x+1OH·S′ (x = 6–10, 12, 14, and 16) do not mix with H2O being quite stable in this solvent, in contrast to the pristine MOF, and exhibit a hydrophobic/superhydrophobic surface as confirmed from the investigation of their water contact angles and capability to remove hydrophobic pollutants from aqueous media.


Table of Contents
Single Crystal X-ray Crystallography Tables Table S1: Selected Crystal Data for UCY-16•6nDMF•nH2O and UCY-16/S (S = Benzene (Bz), Toluene (Tol), Chlorobenzene (PhCl), MeCN) a R = Σ||Fo|-|Fc|| / Σ|Fo|, wR = {Σ[w(|Fo| 2 -|Fc| 2 ) 2 ] / Σ[w(|Fo| 4 )]} 1/2 and b w=1/[σ 2 (Fo 2 )+(mP) 2 +nP] where P=(Fo 2 +2Fc 2 )/3 and m and n are constants     The structural description of UCY-16•6nDMF•nH2O (the asymmetric unit is shown in Fig. S1a) is getting complicated when ligands A and D are taken into account; those in addition to the different coordination behavior of the two butterflylike secondary building units (SBUs) above and below ac plane lead to a unique topological network.Although the coordination spheres of the Cu 2+ ions in the two butterflies are very similar [trigonal bipyramidal for the outer atoms Cu(1), Cu(4) and Cu( 6) and Jan-Teller distorted square pyramidal for the inner atoms Cu(2), Cu(3) and Cu( 5)] their connectivity is different due to symmetry.Butterfly Cu(1) -Cu( 4) is connected to three (one A and two D) AIP ligands above and below the ac plane, while butterfly Cu(5) -Cu( 6) is connected only to two inversion related A ligands. (Figure S1b) Topologically, ligands A and D can be obviously considered as linkers which connect adjacent layers.The butterfly-like SBUs, which were six connected nodes in the kgd net have now different connectivity; butterfly Cu(1) -Cu( 4) is a nine connected node while butterfly Cu(5) -Cu( 6) is an eight connected node.Eventually, though the connectivity of the three connected nodes (ligands B, C and E) remains the same, their topological description changes (related to the kgd net) and the net is transformed to a tetranodal one with stoichiometry (3c)4(3c)2(8c)(9c)2.

Figure S5 :
Figure S5: Powder X-ray diffraction patterns of the as synthesized compound UCY-16•6nDMF•nH2O, along with the simulated pattern from single crystal data and the as synthesized UCY-16•6nDMF•nH2O treated (as described in the experimental part) in the indicated organic solvents for 3 days.

Figure S6 :
Figure S6: Powder X-ray diffraction pattern of the as synthesized UCY-16•6nDMF•nH2O treated (as described in the experimental part) in water for 1 day.

Figure S7 :
Figure S7: TGA graph of the as synthesized compound UCY-16•6nDMF•nH2O.The decomposition of UCY-16•6nDMF•nH2O is a multistep process which begins with the slow removal of the lattice solvent molecules from 20 o C up to ~270 o C (calculated loss  25.6%;found ≈ 25%).The lattice solvent molecule loss is followed by the decomposition of the framework that involves the removal of the AIP 2-/HAIP -ligands which is completed at ~450 o C (calculated loss  47.7%; found ≈ 48%).The residue at 600 o C corresponds to CuO (calculated residue ≈ 26.7%; found ≈ 27%).

Figure S10 :
Figure S10: Part of the framework of UCY-16/Tol (ball and stick model) emphasizing on selected π•••π edge to face and CH3•••π interactions (dashed green lines) between the lattice toluene molecules (in yellow) and the framework.Hydrogen atoms are omitted for clarity.

Figure S11 :
Figure S11: Part of the framework of UCY-16/PhCl (ball and stick model) emphasizing on selected π•••π stacking edge to face interactions (dashed green lines) between the lattice chlorobenzene molecules (in green) and the framework.Hydrogen atoms are omitted for clarity.

Figure S12 :
Figure S12: Part of the framework of UCY-16/MeCN (ball and stick model) emphasizing on selected hydrogen bonding interactions (dashed orange lines) between the lattice MeCN molecules and the framework.Hydrogen atoms are omitted for clarity.

Figure S15 :
Figure S15: TGA graphs of the as synthesized compound UCY-16•6nDMF•nH2O and the exchanged analogues UCY-16/S (S = Bz, Tol, PhCl, MeCN).TG analysis revealed that the decomposition of UCY-16/S (S = Bz, Tol, PhCl, MeCN) is completed in two steps.The first one is attributed to the release of lattice solvent molecules and residual water or DMF molecules and is completed at 255-275 o C whereas the second one is completed at 435-465 o C

Figure S17 :
Figure S17: Part of the framework of UCY-16/C2H5OH (ball and stick model) emphasizing on the hydrogen bonding interactions (dashed orange lines) between the lattice C2H5OH/H2O molecules and the framework.Hydrogen atoms are omitted for clarity.

Figure S18 :
Figure S18: Part of the framework of UCY-16/n-C3H7OH (ball and stick model) emphasizing on the hydrogen bonding interactions (dashed orange lines) between the lattice n-C3H7OH molecules and the framework.Hydrogen atoms are omitted for clarity.

Figure S19 :
Figure S19: Part of the framework of UCY-16/n-C4H9OH (ball and stick model) emphasizing on the hydrogen bonding interactions (dashed orange lines) between the lattice n-C4H9OH molecule and the framework.Hydrogen atoms are omitted for clarity.

Figure S20 :
Figure S20: Part of the framework of UCY-16/n-C5H11OH (ball and stick model) emphasizing on the hydrogen bonding (dashed orange lines) and Van der Waals (dashed magenta lines) interactions between the lattice n-C5H11OH molecules and the framework.Hydrogen atoms are omitted for clarity.

Figure S21 :
Figure S21: Part of the framework of UCY-16/n-C6H13OH (ball and stick model) emphasizing on the Van der Waals interactions (dashed magenta lines) between the lattice n-C6H13OH molecule and the framework.Hydrogen atoms are omitted for clarity.

Figure S22 :Figure S23 :
Figure S22: Part of the framework of UCY-16/n-C7H15OH (ball and stick model) emphasizing on the Van der Waals interactions (dashed magenta lines) between the lattice n-C7H15OH molecule and the framework.Hydrogen atoms are omitted for clarity.

Figure S27 :
Figure S27: TGA graphs of the as synthesized compound UCY-16•6nDMF•nH2O and UCY-16/n-CxH2x+1OH•S′ (x = 1-7).TG analysis revealed that the decomposition of the exchanged analogues UCY-16/n-CxH2x+1OH•S′ (x = 1-7) is completed in two steps.The first step is attributed to the release of lattice alcohol molecules and residual water or DMF lattice solvents and is completed at 260-270 o C whereas the second step is completed at 500 o C and is attributed to the combustion of AIP 2-/HAIP -/n-CxH2x+1O -ligands.Finally, the residue at 600 o C corresponds to CuO. (TableS4)

Table S4 :
Calculated values for solvent removal and ligand combustion along with the experimental values obtained from TG analysis of the