A Guest-Responsive Fluorescent 3D Microporous Metal−Organic Framework Derived from a Long-Lifetime Pyrene Core

Abstract

The carboxylate ligand 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy)-based on the strongly fluorescent long-lifetime pyrene core-affords a permanently microporous fluorescent metal-organic framework, [In(2)(OH)(2)(TBAPy)].(guests) (1), displaying 54% total accessible volume and excellent thermal stability. Fluorescence studies reveal that both 1 and TBAPy display strong emission bands at 471 and 529 nm, respectively, upon excitation at 390 nm, with framework coordination of the TBAPy ligands significantly increasing the emission lifetime from 0.089 to 0.110 ms. Upon desolvation, the emission band for the framework is shifted to lower energy: however, upon re-exposure to DMF the as-made material is regenerated with reversible fluorescence behavior. Together with the lifetime, the emission intensity is strongly enhanced by spatial separation of the optically active ligand molecules within the MOF structure and is found to be dependent on the amount and chemical nature of the guest species in the pores. The quantum yield of the material is found to be 6.7% and, coupled with the fluorescence lifetime on the millisecond time scale, begins to approach the values observed for Eu(III)-cryptate-derived commercial sensors.

Isostructural Metal–Anion Radical Coordination Polymers with Tunable Phosphorescent Colors (Deep Blue, Blue, Yellow, and White) Induced by Terminal Anions and Metal Cations

“…UV/Vis diffuse reflectance spectra of 1, 1 a, and 1 b: The UV/Vis diffuse reflectance spectra of 1, 1 a, 1 b, and the free Hbipo À C ligand were recorded under ambient conditions ( Figure 4). The Hbipo À C itself displays weak absorption bands in the UV/Vis spectral region from 300 to 500 nm, which arise from the p-p* transition of the aromatic rings, [29] and a moderate absorption band at 575 nm, probably arising from the delocalization effect of intermolecular p-p interaction. [40] In 1, these bands are not strongly perturbed upon its coordination to Cd II ; however, a little blueshift of some bands is observed.…”

Biologically derived metal organic frameworks

“…Increasing the conjugation of organic ligand can aid in the formation of MOFs with hydrophilic pores, or that can be used for light absorbing or sensing applications. [30][31][32][33][34][35][36][37][38][39] Ligands such as H4TCPB have been incorporated into MOFs, allowing for selective uptake of p-xylene over other isomers such as m-xylene. [35] While porphyrin based MOFs (Al-PMOF) have been used to harvest light for water reduction.…”

Photoluminescent Metal–Organic Frameworks for Gas Sensing

“…Because liquids are closely related to the surrounding environment and human body, many materials (including MOFs) have been developed for liquid‐phase luminescence sensing of ionic and molecular species 46, 47, 48, 49, 50, 51, 52, 53. In the liquid environment, the types and concentrations of the analytes can be easily controlled for quantitative detection (calibration).…”