Unusually Strong Dipole–Dipole and Dipole–Quadrupole Interactions in a Nanoporous Solid. Crystal Structure and Related Properties of (VO)₃[M(CN)₆]₂·nH₂O (M = Fe, Co)

Abstract

In porous Prussian blue (PB) analogues, the partially naked central metal atoms found at the cavities surface are responsible for many of their physical properties, among them the adsorption potentials. In the as-synthesized PB analogues, such metal sites stabilize water molecules inside the cavity through coordination bond formation. The filling of the cavity volume is completed with water molecules linked to the coordinated ones through hydrogen bonds formation. Vanadyl-based PB analogue shows quite different features. The metal(V) at the cavities surface has saturated its coordination sphere with the O atom of the vanadyl ion (V=O). In this material, the V=O group preserves enough strong dipole moment to stabilize adsorbed species at the cavity through dipole-dipole and dipole-quadrupole in-

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“…The FeC 6 and V­(O/N) 6 octahedra are linked by C–N bonds to generate the three-dimensional framework with K atoms and H 2 O molecules in the space. As shown in Figure b, the XRD patterns are consistent with that of the reported (VO) 3 [Fe­(CN) 6 ] 2 ·9H 2 O, indicating the successful synthesis of KVHCF. After ball milling with Super P, the three main peaks are still observed, while the intensity is significantly reduced, indicating the crystal structure is not destroyed by ball milling.…”

“…The ion diffusion ability and impedance information are also studied via the galvanostatic intermittent titration technique (GITT) and EIS measurement. As shown in Figure a, the ion diffusion coefficient of all of the samples calculated by GITT is between 10 –14 and 10 –9 cm 2 ·s –1 , comparable to most reported PBAs for ZIBs. , The fast ion transport rate derives from the open framework structure (Figure a) and smaller particle size (Figure b). − KVHCF@10%CNT/SP possesses the least Ohmic impedance and charge transport impedance after 80 cycles at 2C (Figure b), which suggests good electronic conductivity and fast ion transport ability.…”

“…The peaks at 2085, 593, and 527 cm –1 belong to the absorption bands involving the CN ligand (ν­(CN), ν­(FeC), and δ­(FeCN)), while the absorption band at 979 cm –1 corresponds to the vanadyl group ν­(VO). The peaks around 3625 and 1606 cm –1 reveal the existence of crystal water. − The Raman spectrum (Figure e) is also obtained to confirm the structural features. The peaks located at 272 and 877 cm –1 are assigned to the bending vibration of VO and stretching vibration of V–O–V, and those at 2055 and 2089 cm –1 are related to the cyanogen group. − …”

“…The synthesis process of the KVHCF sample was the same as described in the article . The synthesis details are listed in the Supporting Information.…”

Fe(L)2[M(CN)4] with L = 4-Ethyl Isonicotinate and M = Ni, Pd, Pt.─A Series of Hofmann-Type Frameworks with Spin Crossover: The Dominant Role of the Fe–NC Coordination Bond

“…tions, depending of the number (n) of weakly bonded water molecules found in the interlayer region. 79,80 These weakly bonded water molecules are stabilized in that region through hydrogen bonding interactions with the coordinated water molecules occupying the axial coordination sites for iron atoms. When the organic ligand is present in the reacting solution, the organic molecules occupy axial coordination sites for the iron atoms, and the formed hybrid solid usually has an anhydrous character.…”