Nano Organic Co‐Crystal Scintillator for X‐ray Imaging

Abstract

Traditional‐metal‐containing scintillators are widely used in X‐ray imaging due to their efficient X‐ray absorption and output of visible light. However, they suffer from heavy‐metal toxicity, environmental stability, harsh preparation, and afterglow. Metal‐free organic scintillators show a rising momentum, especially organic‐halogen‐containing molecules. Halogens are introduced to improve their X‐ray absorption, but the resulting increase in spin–orbit coupling leads to significant delayed fluorescence or phosphorescence, affecting the response speed to X‐rays. Moreover, there is still insufficient practice in fabricating microstructured organic scintillators for high spatial resolution of imaging. Herein, the preparation of nano organic co‐crystals (t‐Bpe‐IFB co‐crystal, abbreviated as BIC, t‐Bpe for trans‐1,2‐bis(4‐pyridyl)ethylene, and IFB for 1,3,5‐trifluoro‐2,4,6‐triiodobenzene) and its application in X‐ray imaging are explored. In contrast to previous single organic‐halogen‐containing molecules, BIC generates nanosecond‐scale fluorescence through the charge‐transfer state of the donor–acceptor. Its high iodine content ensures large X‐ray absorption, strong radioluminescence, and a low detection limit of 85 nGyair s−1. The composite film made of nano‐sized BICs and polydimethylsiloxane exhibits a high spatial resolution of 16.7 lp mm−1. Herein, the application of organic co‐crystals is expanded and ideas are provided for the development of new scintillators.

Halogen-bonded charge-transfer co-crystal scintillators for high-resolution X-ray imaging

“…Meanwhile, charge transfer between the donor and acceptor may potentially enhance the carrier transport efficiency of the material, thereby improving its scintillation performance. 20,21 Recently, Sun et al 22,23 demonstrated the feasibility of this strategy through their report on the organic co-crystal BIC scintillator.…”

Mechanochemical Synthesis of Cuprous Complexes for X-ray Scintillation and Imaging

“…As shown in Table S1 and Figure d,e, a unit cell of both Cu-1 and Cu-2 single crystals consists of two Cu­(I) coordination molecules and two acetonitrile molecules, with each pair of molecules exhibiting two I···H–C interactions at distances of 3.888 Å (Cu-1) and 3.857 Å (Cu-2), respectively. The shorter I···H–C interactions in Cu-2 may restrict molecular vibration, thereby constraining nonradiative transition pathways. , Furthermore, we employed CrystalExplorer software to analyze the Hirshfeld surfaces and the distribution of different intermolecular interactions by generating two-dimensional fingerprint plots of these crystals. , As illustrated in Figure S4 and the pie charts in Figure h,i, compared with Cu-1, which has contributions from H···others interactions (73.1%), C···others interactions (18.5%), and I···others interactions (3.9%), the replacement of PH-Br in Cu-2 results in a more diverse array of intermolecular interactions, including H···others interactions (77.3%), C···others interactions (18.8%), I···others interactions (3.5%), and Br···others (4.9%). These plentiful intermolecular interactions effectively constrain molecular vibration and rotation, consequently further suppressing the nonradiative transition process. , Also, it is further supported by the calculated nonradiative transition rates ( k nr ), where the k nr values decreased from 6.61 × 10 4 s –1 in Cu-1 to 5.60 × 10 4 s –1 in Cu-2, leading to a significant enhancement of the RL intensity for Cu-2 in the solid-state. ,,, …”

Strain-Released Cs5Cu3Cl6I2 Scintillators by Rb+ Doping for High-Resolution X-Ray Imaging

“…X-ray detection technologies play a crucial role in various applications, including medical imaging, nondestructive testing, and security inspection. − Scintillation X-ray detectors are widely utilized, and scintillators are essential components of these detectors. − Traditional scintillators like CsI:TI OS:Tb, NaI:TI, and LYSO:Ce are commercially available. − However, these scintillators face challenges, such as a complex preparation process, high cost, light scattering, long afterglow, and poor stability, limiting their widespread application. − Moreover, the incorporation of toxic elements like TI in high-performance scintillators poses significant safety risks . Therefore, there is an immediate need to investigate advanced scintillator materials with high performance.…”