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Chapter 3 33
All Ru-MOFs 1-4 of the general formula [Ru3(BTC)2Yy]n·G g (Y = Cl, F, OH…; G = H2O,
CH3COOH, (CH3)3CCOOH, H3BTC,…; 0 ≤ y ≤ 1.5) were obtained employing [Ru2(OOCR)4X]
or [Ru2(OOCCH3)4]A precursors under solvothermal conditions in a similar way as we
reported earlier. [82] The subsequent activation (i.e., removing of the incorporated
solvent/guest molecules) was conducted at 150 °C for 24 h under dynamic vacuum (ca.
10 -3 mbar). As revealed by the PXRD patterns (Figure 3.3), the prepared Ru-MOFs 1-4 are
phase-pure crystalline solids that are isostructural to [Cu3(BTC)2]n. Ru-MOFs 2 and 4
showed better crystallinity compared to the samples 1 and 3. The coordination of the
carboxylic groups of framework BTC in the activated Ru-MOF samples is indicated by the
strong-intensity bands at 1429 cm -1 and 1359 cm -1 in the FT-IR spectra (Figure 3.4).
Notably, the Ru-MOFs obtained from [Ru2(OOCCH3)4]A, in which Y = [BF4] - and [BPh4] - ,
show similar IR spectra with the other two samples. In other words, the incorporation of
[BF4] - counter-ion in the structure of 3 can be ruled out, as no characteristic ν(B-F) band
was observed at 1073 cm -1 . It is not possible to unambiguously determine the presence of
[BPh4] - based only on the IR spectra because of the overlapping vibrations of [BPh4] - and
BTC. Further analytical evidences in this respect will be discussed later.
Figure 3.4. IR spectra of the activated Ru-MOFs 1-4.