It is well known that metal-organic framework compounds (MOFs), which are highly porous crystalline materials, remain a center of attention because of their unique gas adsorbing abilities. However, combining capture of adsorbed materials with further catalytic transformation is one of the major challenges of clean and renewable energy production.
Photoactive properties of titanium(IV) oxide species are well known [e.g. 1], therefore it is not surprising that Serre et al observed reversible photochromic behavior induced by alcohol adsorption using MOF MIL-125, constructed from titanium-oxo-hydroxo clusters and dicarboxylate linkers [2]. Furthermore, an exciting result of capture and efficient use of adsorbed CO2 has been reported by Li et al [3]. This research group demonstrated using the amino-functionalized MIL-125 Ti(IV) MOF, also known as NH2-MIL-125(Ti) (Fig. 1, 22-1070) as a visible light photocatalyst induced CO2 reduction to HCOO–. In later work, another successful photocatalysis for CO2 reduction was developed using a gold decorated MOF [4].
Fig. 1. Schematic view of the cages of MIL-125(Ti)-NH2
NH2-MIL-125(Ti), a thermally robust material, has a BET surface area of 1530 m2·g-1. It employs 2-aminobenzenedicarboxylic acid as an organic spacer linking Ti8O8(OH)4 metal clusters (for more details review our corresponding product sheet).
Promising photocatalytic properties of NH2-MIL-125(Ti) encouraged other research groups to incorporate noble metal nanoparticles in their MOFs as cocatalysts. Pt@Ti-MOF-NH2 [5] and Pd@Ti-MOF-NH2 [6] exhibit efficient photocatalytic activities for hydrogen production from aqueous solutions of triethanolamine and formic acid respectively. The photocatalytic performance of M/NH2-MIL-125(Ti) (M=Pt and Au) has been investigated using visible-light for the production of hydrogen and formate under Pt- and Au-loading of NH2-MIL-125(Ti) [7]. Successful visible-light-driven H2 production could also be achieved in a noble-metal-free system by encapsulating a Co(II) catalyst inside the cages formed within the MIL-125-NH2 photosensitizer MOF [8].
MIL-125-NH2 is a promising catalyst for various organic transformations. This material was successfully applied in photocatalytic oxidation of amines to imines [9] and aromatic alcohols to aldehydes [10] and also for the cycloaddition of epichlorohydrin and the oxidative desulfurization of dibenzothiophene [11].
References:
Featured Product:
22-1070 Hexakis[µ-(2-amino-1,4-benzenedicarboxylato)][tetra-µ-hydroxyocta-µ-oxooctatitanium], NH2-MIL-125(Ti), AYRSORB™ T125 (1309760-94-8)
Related Products & Resources:
Metal Organic Frameworks
NH2-MIL-125(Ti), AYRSORB™ T125
MOFs and Ligands for MOF Synthesis
Metal Organic Frameworks and Ligands for MOF Synthesis Booklet