Chemical instability of Cu3(BTC)2 by reaction with thiols

Abstract

In contrast to Fe(BTC) (BTC: 1,3,5-benzenetricarboxylate), the crystal structure of Cu 3 (BTC) 2 , a commercial metal organic framework widely used as solid catalyst, collapses when contacted with thiols under mild reaction conditions forming copper nanoparticles.

Deactivation of Cu3(BTC)2 in the Synthesis of 2-Phenylquinoxaline

“…In another precedent, the crystal structure of Cu 3 (BTC) 2 was collapsed during the aerobic oxidation of thiophenol at 70°C in acetonitrile medium after 10 min due to the strong Cu 2? -thiol bond [13]. We note, however, that in the present case, the experimental conditions are milder, since the reaction is performed at room temperature and the reaction times are comparatively shorter.…”

“…Currently, there is a need to delineate the stability of MOFs compared with zeolites and other related metal oxides with the aim to clarify if MOFs could be used as industrial heterogeneous catalysts. We have already demonstrated that Cu 3 (BTC) 2 undergoes major changes in its crystal structure by forming Cu nanoparticles when reacted with aliphatic/aromatic thiols [13]. Similarly, destruction of Cu 3 (BTC) 2 framework was observed in the oxidation of CO [33].…”

“…There are examples showing that some MOFs are initially active as catalysts but, however, deactivate during the course of the reaction due to the incompatibility of MOF structure with solvents or reagents under the conditions required for the catalysis [12]. Specifically, one MOF with large interest as heterogeneous catalyst, but that has been found to become destroyed in some reactions is Cu 3 (BTC) 2 (BTC: 1,3,5-benzenetricarboxylate) [13]. This MOF is amply used as heterogeneous catalysts in many different types of reactions including cyanosilylation [14], epoxide rearrangement [15], ring opening of epoxide [16], acetalization of aldehydes [17], oxidation of xanthene [18] and Knoevenagel condensations [19].…”

Deactivation Pathways of the Catalytic Activity of Metal–Organic Frameworks in Condensation Reactions

“…[17,25] However, there is a paucity of detailed studies on the deactivation of Fe-containing MOFs as catalysts for liquid-phase organic reactions. Recently, we have shown that Cu 3 (BTC) 2 decomposes in the presence of thiophenol, [26] whereas Fe(BTC) is stable under identical experimental conditions effecting the aerobic oxidation of thiophenol to diphenyldisulfide with complete selectivity. [27] Information about deactivation mechanisms and identification of catalytic poisons formed during the course of the catalytic reaction are necessary to assess the stability of the catalyst and the viability of a particular reaction.…”

Metal Organic Frameworks as Solid Catalysts in Condensation Reactions of Carbonyl Groups

“…[37] Considering that the thermal and chemical stability of MOF is not as high as those of zeolites, the issue of recyclability and catalyst stability is very important in the area of use of MOFs as catalysts and has been specifically addressed in the present review. [37] Considering that the thermal and chemical stability of MOF is not as high as those of zeolites, the issue of recyclability and catalyst stability is very important in the area of use of MOFs as catalysts and has been specifically addressed in the present review.…”