The nanoporous structures of metal-organic frameworks (MOFs) can be functionally regulated according to specific targets of interest

and thus such types of solids can be considered as promising industrial catalytic materials. Since interface microenvironments and catalytic properties of MOFs might be affected by the solvents

it is necessary to study the influence of solvent effects on their catalytic activities. Although MOFs with coordinatively unsaturated metal sites (CUMs) have shown promising applications in liquid-phase catalysis

the related solvent effects on the Lewis acid catalytic performance of these CUMs are seldom investigated. In this work

density functional theory calculations were conducted to investigate the solvent effects on the properties of the Lewis acid sites in two typical MOFs

Cu-BTC and MOP-15

where the COSMO (conductor-like solvent model) was used to mimic the dielectric response of the solvent environments. Different relative dielectric constants were considered

including in vacuum

toluene

ethyl acetate

1

2-dichloroethane and acetonitrile. Using CO as the probe molecule

the solvent effects were examined by exploring the geometry parameters

the Mulliken charges

and the vibrational frequency as well as the adsorption energy of CO molecule around those CUMs. The strengths of Lewis acid sites could be enhanced with the increase of the dielectric constant. Further

the solvent effects became more evident in CUMs when the organic linkers had higher electronegativity. These observations provide fundamental insights into the regulation of the liquid-phase catalytic activity of MOFs using specific solvents.