We report the synthesis and structural diversity of Zn(II) metal-organic framework (MOF)
with in situ formation of tetrazole ligand
3-ptz
[
3-ptz
= 5-(3-pyridyl)tetrazolate] as a function pH. By varying
the initial reaction pH, we obtain high-quality crystals of the noncentrosymmetric
three-dimensional MOF
Zn(3-ptz)
2
, mixed phases
involving the zinc-aqua complex [Zn(H
2
O)
4
(3-ptz)
2
]·4H
2
O, and two-dimensional MOF crystals Zn(OH)(3-ptz)
with a tunable microrod morphology, keeping reaction time, temperature,
and metal–ligand molar ratio constant. Structures are characterized
by X-ray diffraction, scanning electron microscopy, Fourier transform
infrared spectroscopy, and UV–vis spectroscopy. We discuss
the observed structural diversity in terms of the relative abundance
of hydroxo-zinc species in solution for different values of pH.
In the present work, the synthesis and structural characterization of four new polyoxovanadoborate (BVO) frameworks based on the [V12B18O60H6](10-) polyanion are reported: (NH4)8(1,3-diapH2)[V12B18O60H6]·5H2O (1), K8(NH4)2[V12B18O60H6]·18H2O (2), K10[V12B18O60H6]·10H2O (3) and K8Cs2[V12B18O60H6]·10H2O (4). A global antiferromagnetic behaviour is observed for these 10V(IV)/2V(V) mixed valence clusters. The magnetic data of 1, 2 and 3, which present different countercation environments, show that 1 is more coupled than 2 and 3. DFT calculations show that the positive charges strongly influence the polarization mechanism of the spin density of the vanadyl groups and the extent of the magnetic orbitals, therefore corroborating the experimental observation of the quenching effect of the magnetic coupling between vanadium centres of 2 and 3.
Magnetic analogues of Alq3 give rise to molecular/ferromagnetic interfaces with specific hybridization, opening the door to interesting spintronic effects.
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