# Encapsulation of a Highly Acid-Stable Dicyano-Bodipy in Zr-Based Metal–Organic Frameworks with Increased Fluorescence Lifetime and Quantum Yield Within the Solid Solution Concept

## TL;DR

Researchers created a more stable dye variant and embedded it into metal-organic frameworks, significantly improving its fluorescence lifetime and brightness.

## Contribution

A new acid-stable dicyano-Bodipy was synthesized and successfully incorporated into MOFs, enhancing its fluorescence properties.

## Key findings

- Dicyano-Bodipy@MOF composites showed up to 9.0 ns photoluminescent lifetimes, eight times longer than the neat dye.
- Post-synthetic incorporation into DUT-67 MOF increased the quantum yield to 77%, compared to 9% for the neat dye.
- Incorporation methods affected BET surface areas, with lower values observed for dicyano-Bodipy@MOF composites.

## Abstract

In this work, we have synthesized a more acid-stable variant of the classic chromophore difluoro-Bodipy by substituting the difluoro ligands at boron with cyano groups. This dicyano-Bodipy variant allowed the in situ incorporation during the MOF formation under acidic conditions and was investigated for the first time as dye@MOF composites using both post-synthetic and in situ incorporation into the zirconium-based metal–organic frameworks (MOFs) UiO-66, MOF-808, DUT-67, and MIP-206. The successful incorporation of dicyano-Bodipy was confirmed by PXRD, N2 sorption, digestion UV–Vis, and fluorescence spectroscopy. Depending on the incorporation method used, significant lower BET surface areas could be determined. The luminescence properties of the resulting dicyano-Bodipy@MOF composites from the in situ incorporation had up to almost eight-fold extended photoluminescent lifetimes of 9.0 ns, compared to the neat dye in its solid state with 1.2 ns, which suggests the formation of a solid solution in which the incorporated Bodipy is protected from external influences within a well-defined MOF pore. The quantum yield could be enhanced to as high as 77% through post-synthetic incorporation into the MOF DUT-67, compared to the neat dye in its solid state, with 9%.