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6 Summary and Outlook<br />
Among all MOF’s features, one of the most important and interesting characteristics is the<br />
presence of coordinatively unsaturated metal sites (CUS). Due to much stronger affinity<br />
of many “bare” metal-ions towards some gases (e.g. H2, CO2, CH4) and organic molecules,<br />
design of CUSs within MOFs has been a key factor in enhancing MOFs performance in a<br />
variety of applications such as gas storage, gas selectivity and catalysis.<br />
HKUST-1 ([Cu3(BTC)2]n, Cu-BTC) represents one of the well-known and investigated<br />
MOFs where removal of the coordinated water molecules and, thus, generation of CUSs<br />
could be easily achieved upon heating under vacuum. Moreover, [Ru3(BTC)2Yy]n (Ru-<br />
BTC), which is mixed-valence ruthenium structural analog of HKUST-1, has been<br />
elaborated. Interestingly, this ruthenium MOF exhibits sufficient chemical as well as<br />
thermal stability, and offers rich photo/redox chemistry. Hence, in this dissertation Cuand<br />
Ru-MOFs of [M3(BTC)2Yy]n family (M = Cu, Ru, Mo, Cr, Ni, Fe; x = 0 or 1.5, respectively)<br />
have been chosen as candidates to study the modification of MOF’s local structures (via<br />
modification of CUSs, defects engineering, for instance) and its impact on their properties.<br />
First of all, controlled secondary building units approach (CSA) has been employed to<br />
study the (optimized) formation of isostructural Ru II,II and Ru II,III analogs of HKUST-1.<br />
Notably, compared to the Cu-BTC, the composition and local structure of the Ru-BTC<br />
([Ru3(BTC)2Yy]n·G g) turn to be more complex due to the mixed-valence oxidation state of<br />
Ru-centers. The last requires presence of additional counter-ions X from the employed<br />
Ru-SBUs to compensate the charge of [Ru2] 5+ PW units. Besides, some crucial synthetic<br />
parameters like solvents mixture (H2O: AcOH = 1:0.05) lead to the presence of residual<br />
acetic acid/acetate (as counter-ions X, guest molecules/species G or both) in the final<br />
frameworks. By utilizing distinct Ru II,III -SBUs (either [Ru2 II,III (OOCR)4X] or<br />
[Ru2 II,III (OOCCH3)4]A) with various nature of counter-ions X and A and alkyl groups -R, the<br />
local environment of the metal sites in the obtained isostructural MOF solids could be<br />
tuned to a certain extent. Thus, employment of the [Ru2 II,III (OOCCH3)4]A (where A is a<br />
weakly coordinating anion) instead of [Ru2 II,III (OOCR)4X] (where X is a strongly
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