Cuboctahedral [In36(μ-OH)24(NO3)8(Imtb)24]MOF with Atypical Pyramidal Nitrate Ion in SBU: Lewis Acid-Base Assisted Catalysis and Nanomolar Sensing of Picric Acid.

Abstract

A robust and multifunctional cuboctahedral [In36(μ-OH)24(NO3)8(Imtb)24] MOF (In(Imtb)-MOF) with an atypical pyramidal nitrate ion-containing hitherto unknown SBU core [In9(μ-OH)6(NO3)] is reported. The intra- and interlayer nitrate ions adopt pyramidal and inverted pyramidal shapes, which separates the active indium site [(In3(μ-OH)2)NO3-(In3(μ-OH)2)] and linear In3(μ-OH)2 by 0.5 and 0.9 nm, respectively. Additionally, the high density of active metal sites shows remarkable catalytic activity with higher TOF even for sterically hindered substrates in Strecker synthesis and CO2 cycloaddition. Moreover, the luminescence behavior of In(Imtb)-MOF and the presence of uncoordinated nitrogen atoms are exploited for selective sensing of explosive trinitrophenol (TNP) with a detection limit (LOD) of 2.3 ppb.