Temperature-dependent interchromophoric interaction in a fluorescent pyrene-based metal-organic framework.

ABSTRACT: Compounds exhibiting tuneable fluorescence emission upon heating or cooling are considered smart materials as their optical properties can be exquisitely controlled by adjusting the external temperature. Herein, we report such a material, which is a porous pyrene-based metal-organic framework with a chemical formula of [Mg_1.5(HTBAPy)(H₂O)₂]·3DMF (H₄TBAPy = 1,3,6,8-tetrakis(p-benzoic acid)pyrene), named SION-7. The bulk solid material of SION-7 can display either monomer or excimer fluorescence emission due to the temperature-dependent extent of interchromophoric interactions between the HTBAPy^3- ligands within the framework. Consequently, the fluorescence emission colours gradually change from blue at low temperature (80 K) to yellow-green at high temperature (450 K). Interestingly, while kept in a relatively wide temperature range of 80-200 K, SION-7 displays a structured monomer-like spectrum and its colour changes reversibly from deep to light blue. Ex situ variable-temperature (100-350 K) single-crystal X-ray diffractometry studies revealed the impact of solvent content on the optical properties of SION-7, and illustrated the correlation between the position of the phenylene groups of the HTBAPy^3- ligands at different temperatures and the interchromophoric interaction. Our study demonstrates a step forward towards the design of tuneable thermofluorochromic materials sought by optoelectronics.

SUBMITTER: Gladysiak A 

PROVIDER: S-EPMC6585595 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature