Connecting structure with function in metal–organic frameworks to design novel photo- and radioluminescent materials

Abstract

The exemplary structural versatility and permanent porosity of Metal-Organic Frameworks (MOFs) and their consequent potential for breakthroughs in diverse applications have caused these hybrid materials to become the focus of vigorous investigation. These properties also hold significance for applications beyond those traditionally envisioned for microporous materials, such as radiation detection and other luminescence-based sensing applications. In this contribution we demonstrate that luminescence induced by ionizing radiation (also known as scintillation) is common in appropriately designed MOFs and describe how this property can be harnessed to generate novel materials useful for detecting radiation. Through a diverse selection of MOFs, we explore the structural properties of MOFs that give rise to scintillation and photoluminescence in these materials. These results enable us to define a new structure-based hierarchical system for understanding luminescent properties in MOFs. Finally, we describe some performance metrics for MOF-based scintillation counters, such as luminosity and resistance to radiation damage, and discuss how these materials relate to the current state of the art in scintillation counters.

Anthracene-Based Lanthanide Metal-Organic Frameworks: Synthesis, Structure, Photoluminescence, and Radioluminescence Properties

“…Further, a Stokes shift was observed among the structures as follows: 60 nm for 1 (380 nm ex-max to 440 nm em-max ), 65 nm for 2 (380 nm ex-max to 435 nm em-max ), 50 nm for 3 (389 nm ex-max to 430 nm em-max ) and 30 nm for 4 (400 nm ex-max to 430 nm em-max ), all of which are smaller than the 87 nm observed for H 2 ADC. Except for 4, the Stokes shift values are larger than the 41 nm observed in Zn-PCN-14, which contains the larger and rotatable anthracene liker, 5,5 -(anthracene-9,10-diyl)diisophthalinic acid (DPATC) [2]. With the exception of Structure 3, the peaks are more defined than those observed in Zn-PCN-14.…”

“…For Structure 2 (Tb), lifetimes τ 1 = 0.2 ns and τ 2 = 0.5 ns and weighted average lifetime τ o = 0.3 ns are much shorter than the 4.9 ns, 16 ns, and 9.5 ns, respectively, we determined for H 2 ADC (ESI Table S2). These lifetimes are also shorter than the average lifetime value of τ o = 2.0 ns reported elsewhere for anthracene in monomeric isolated arrangements [39] and shorter than τ o = 5 ns reported for Zn-PCN-14 [2]. which corresponds to two different photo emissive rates, where I is the intensity, τ is the time, τ1 and τ2 are their corresponding excited state decay lifetimes, and α is the pre-exponential factor.…”

“…It is speculated, however, that following direct excitation the photoemissions of the latter two metals ions would be weak or non-existent due to their low molar absorption coefficient (typically lower that 10 L mol −1 cm −1 ) [1][2][3][4]. Time-resolved photoluminescence decay: Time-resolved photoluminescence measurements were also acquired to further investigate the local environment of the anthracene units in the 3-D networks.…”

“…Their 2-D and 3-D networks offer the opportunity to fine-tune the luminescence characteristics of the organic linker molecules by isolating them in well-defined environments [1][2][3][4][5][6]. Of interest to us is the potential of MOFs as radioluminescent (scintillating) materials for the detection of ionization radiation, including neutrons, protons, and gamma rays.…”

Structural Transformation and Gas Adsorption Properties of Interpenetrated IRMOF-8

“…10,11 It was very recent that the synthesis and structure of the interpenetrated IRMOF-8 was reported and its gas-adsorption and photoluminescence properties were explored. 12,13 Interestingly, the CO 2 uptake of the interpenetrated IRMOF-8 (SUMOF-3) was greatly enhanced, compared to that of the original IRMOF-8, at pressures relevant for capturing CO 2 without compressing flue gases. 12 In this study, we have developed an interpenetrated IRMOF-8 using deferent synthetic methods from the previous ones to explore its structural characteristics and gas absorption abilities.…”