Highly Active La(III)‐Based Metal‐Organic Framework as a Heterogeneous Lewis Acid Catalyst for Friedel‐Crafts Alkylation

Abstract

In this study, a novel La(III)‐based two‐dimensional (2D) metal‐organic framework, [La2/3(qptca)1/2] (referred to as SLX‐2), from LaCl3 and 1,1′ : 4′,1′′ : 4′′,1′′′ : 4′′′,1′′′′‐quinquephenyl]‐2,2′′,2′′′′,5′′‐tetracarboxylic acid (H4qptca) was synthesized by conventional solvothermal method and thoroughly characterized by using X‐ray single‐crystal diffraction, powder X‐ray diffraction, and thermogravimetric analyses. The 2D SLX‐2 features a unique lanthanum center exposed to the skeleton and was used as an efficient Lewis acid catalyst for the Friedel‐Crafts alkylation of indole and pyrrole with β‐nitrostyrene along with a wide substrate scope, giving the desired products in good‐to‐high yields under the optimal reaction conditions. Furthermore, the catalyst was used for twenty cycles, with nearly no effect on its activity, and the reaction was heterogeneous in nature. Moreover, compared to the previous hydrogen‐bond‐donating MOF catalysts for such alkylation reactions, SLX‐2 showed an excellent stability toward harsh acidic and basic environment, and gave comparable catalytic activities.

Bifunctional MOFs in Heterogeneous Catalysis

“…The alkylation of indole and pyrrole with β-nitrostyrene with a wide substrate scope gave the desired product with high yield and recyclability. 61 As an example of unusual Lewis acidity in MOFs, the example of easily modifiable nature of the ligand was exploited in preparing Pd-mono(thiocatecholato) units inside the MOF UiO-66. 85 This modified MOF exhibited excellent regioselectivity toward the sp 2 carbon, oxidation of alcohols to ketones, etc.…”

“…Recently, lanthanide centers were explored as possible Lewis acid catalytic centers in the compound, [La 2/3 (qptca) 1/2 ] (qptca = 1,1′:4′,1′′:4″,1‴:4′′′,1⁗-quin­que­phen­yl]-2,2′′,2′′′′,5′′-tetra­car­box­ylic acid), toward the Friedel–Crafts reaction. The alkylation of indole and pyrrole with β-nitrostyrene with a wide substrate scope gave the desired product with high yield and recyclability …”

A recyclable MOF@polymer thin film composite for nanomolar on-site fluorometric detection of heavy metal ion and anti-histamine drug and efficient heterogeneous catalysis of Friedel–Crafts alkylation

“…In addition, this reaction is also used by many researchers to demonstrate the influence of different functionalities embedded within the framework and to establish size-selective catalysis. 21 The Friedel-Crafts alkylation reaction between IND and NS has been reported by using a series of MOFs that include CSMCRI-17, 22 La(III)-MOF, 23 urea-modified MOFs, 24 urea-modified UiO-67, 25 UiO-66(Ce), 26 amide functionalized MOFs, 27 Cu 3 (BTC) 2 28 and squaramide functionalized Zr-MOF. 29 Thus, the present work aims to address the influence of the thioureido functionality on Al-based MOFs as well as size-selective catalytic behavior.…”

Construction of a terbium-based metal–organic framework for specific detection of MnO4− in aqueous media

“…In addition, two novel lanthanide metal-based MOFs, namely Eu-MOF (referred to as SLX-1) and La-MOF (referred to as SLX-2), were achieved by our group and used as a specific chemosensor of Fe 3+ and a Lewis acid catalyst in the Friedel–Crafts alkylation of indole and pyrrole with β-nitrostyrene, respectively. 44,45 These results thus prompted us to further investigate other lanthanide metal-based MOFs derived from H 4 qptca. Herein, a new luminescent terbium-based metal–organic framework, [Tb(qptca) 1/2 (H 2 qptca) 1/2 (H 2 O) 2 ] n , (referred to as SLX-3), based on the H 4 qptca ligand was successfully obtained by traditional solvothermal conditions.…”