Chemical Engineering of Photoactivity in Heterometallic Titanium–Organic Frameworks by Metal Doping

Abstract

We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post-synthetic metallation of MOFs, our approach is well-fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band-gap and electronic properties of the porous solid. Changes in the band-gap are also rationalized with computational modelling and experimentally confirmed by photocatalytic H production.

De novo synthesis of mesoporous photoactive titanium(iv)–organic frameworks with MIL-100 topology

“…S30†). This value lies between those reported for MIL-125 (3.68 eV)46 or MUV-10(Ca) (3.10 eV)22 and is compatible with UV light photoexcitation. This was confirmed by irradiating a suspension of the solid in dry THF with UV-B light ( λ = 280–315 nm).…”

“…18) and MTM-1,19 Ti 3 O in COK-69,20 heterometallic clusters like Ti 8 Zr 2 O 12 in PCN-415 (ref. 21) and Ti 2 M 2 O 2 (M = Ca, Mn) in MUV-10,22 or simple titanium nodes in NTU-9 (ref. 23) and Ti-CAT-5,24 confirm the complexity for targeting the formation of specific MOF architectures due to the difficulties in controlling the formation of persistent SBUs.…”

Electroactive Metalorganic Frameworks

“…Recently, Marti‐Gastaldo and co‐workers introduced a new heterometallic titanium‐organic framework coined MUV‐10 (MUV stands for Materials of Universidad de Valencia), whereby the MOF contains heterometallic SBUs . In general, this class of MOFs (MUV‐10(Ca)) or (MUV‐10(Mn)) can be synthesized from a reactive precursor solution comprising titanium(IV) isopropoxide, calcium chloride/manganese chloride, trimesic acid (H 3 btc; benzene‐1,3,5‐tricarboxylic acid) and acetic acid modulator dissolved in N,N‐dimethylformamide.…”

Metal‐organic Frameworks Incorporating Multiple Metal Elements

“…The enzyme‐like catalytic activity of this material arises from the ability to isolate oxo‐bridged iron units within the multi‐metal MOF SBU . Recently, Martí‐Gastaldo et al . have reported the modification of the electronic structure of a new titanium MOF by adding a second metal cation, resulting in a tuning of the material band‐gap, and consequently its photocatalytic activity.…”