Cr–Ti Mixed Oxide Molecular Cages: Synthesis, Structure, Photoresponse, and Photocatalytic Properties

Abstract

The solvothermal reaction of titanium isopropoxide and chromate in the presence of benzoate produced two novel host−guest clusters encapsulating Cs + or H 3 O + , (H 3 O)@Ti 7 Cr 14 and Cs@Ti 7 Cr 14 . The most remarkable feature is that the Ti 7 O 7 ring is concentrically embraced by a Cr 14 O 14 ring to form a rigid Ti 7 Cr 14 host. ESI-MS and 133 Cs NMR revealed that the overall framework structures are preserved, whereas the benzoate ligands on the two clusters may be labile in solutions. Both (H 3 O)@ Ti 7 Cr 14 and Cs@Ti 7 Cr 14 exhibit good UV−vis light-responsive properties and photocatalytic activities, with absorption edges extending up to 780 nm. Cs@Ti 7 Cr 14 is an effective visible-lightresponsive photocatalyst in both the heterogeneous methylene dye degradation and homogeneous CO 2 cycloaddition reaction under mild conditions like room temperature and 1 bar of CO 2 . According to the mechanism studies, Cs + , as a rigid guest, can significantly improve the photogenerated charge separation efficiency of the Ti 7 Cr 14 host, thereby improving its interface charge separation properties, photocurrent, and photocatalytic activities. Our findings not only provide new members of heterometallic titanium oxide clusters to enrich the metal oxide cluster family but also open up new possibilities for their photoresponses, which may play an important role in solar energy harvesting for sustainable chemistry.

Divalent Heterometal Doped Titanium-Oxide Cluster Polymers: Structures, Photoresponse, and Photocatalysis

“…The positive slopes are consistent with n-type semiconductors . Since the conduction band bottom of many n-type semiconductors is 0.1 V below E fb , − the pseudo conduction band (pCB) potential of Ti 10 Cd 2 is −0.42 V vs NHE. Meanwhile, the pseudo valence band (pVB) potential of Ti 10 Cd 2 is +1.96 V vs NHE.…”

Coordination Synergy between Iridium Photosensitizers and Metal Nanoclusters Leading to Enhanced CO2 Cycloaddition under Mild Conditions

“…Moreover, from the electrochemical impedance spectra (EIS, Figure 7c), it can be observed that the hybrid Mn 2 Cd 4 /Ir(Cltpy) 2 system exhibits a smaller arc radius compared to the Mn 2 Cd 4 cluster, indicating lower charge transfer resistance and higher photoelectron transfer efficiency for the hybrid Mn 2 Cd 4 /Ir(Cltpy) 2 system. 2 Further evidence supporting the higher catalytic activity of the hybrid Mn 2 Cd 4 / Ir(Cltpy) 2 system is provided by photoluminescence measurements carried out at an excitation wavelength of 521 nm (Figure 7d). As seen in Figure 7d, the hybrid Mn 2 Cd 4 / Ir(Cltpy) 2 system exhibits an emission band close to 527 nm, which is significantly less intense than that of Ir(Cltpy) 2 , suggesting that the hybrid Mn 2 Cd 4 /Ir(Cltpy) 2 system has a greater charge separation efficiency.…”

“…Carbon dioxide is widely recognized as the main greenhouse gas contributing to global warming. , It is also a widely available, affordable, and benign source of carbon in the synthetic chemist’s toolbox . Thus, developing an effective method to use CO 2 has implications for environmental conservation and sustainable chemistry.…”

Ligation of Titanium-oxide and {Mo2} Units for Solar CO2 Storage

“…This is different from many other Ti-oxide clusters containing solely benzoate ligands, as the hydrophobic benzene rings often render them very soluble in nonpolar solvents and act as homogeneous catalysts in photocatalytic CO 2 /epoxide cycloaddition. [10][11][12]33 Therefore, the low solubilities of Ti 6 Mo 4 and Ti 4 Mo 4 could be attributed to the Mo�O terminal bonds. The catalytic reaction was conducted neatly at room temperature and 1 atm of CO 2 , with 1a serving as both the solvent and the reactant.…”

“…Titanium-oxide clusters (TOCs) are a category of molecular compounds characterized by discrete titania cores that are passivated with terminating ligand shells. These clusters serve as molecular counterparts to TiO 2 nanoparticles (NPs). , TOCs have garnered significant attention in recent years owing to their precisely engineered atomic architectures and considerable potential in the field of photocatalysis. − A TOC may be effective in photocatalytic CO 2 /epoxide cycloadditions. − Nevertheless, due to the comparable intrinsic band gap between TOCs and TiO 2 NPs, it is common for TOCs to demonstrate a relatively limited capacity for absorbing solar radiation.…”