Effect of CH3OH on the luminescent properties of the [Zn(sfdb)(bpy)(H2O)]n · 0.5nCH3OH metal-organic framework

- TDDFT method is used to study the excited state hydrogen bonding.
- The origin of the luminescence of the MOF is LLCT.
- The hydrogen bond between CH3OH and MOF leads to enhanced luminescence.

The influence of CH3OH solvent on the luminescent properties of the [Zn(sfdb)(bpy)(H2O)]n · 0.5nCH3OH (sfdb = 4,4-sulfonyldibenzoic acid, bpy = 2,2-bipyridine) metal-organic framework (MOF) was investigated by considering the hydrogen bond between CH3OH and [Zn(sfdb)(bpy)(H2O)]n in an electronically excited state using density functional theory and time-dependent density functional theory methods. The calculated geometry, infrared spectrum, and UV-vis spectrum in the ground state are consistent with the experimental results. The frontier molecular orbitals and electronic configuration indicated that the origin of the luminescence is ligand-to-ligand charge transfer rather than ligand-to-metal charge transfer, as has been previously proposed. We found that the O3⋯H11 hydrogen bond is weaker in the excited state than in the ground state, and the weaker hydrogen bond in the electronically excited state should enhance the luminescence. The results show that the CH3OH solvent changes the luminescence properties of [Zn(sfdb)(bpy)(H2O)]n, which provides potential opportunities for the design of diverse luminescent MOFs.