A Scintillating One-Dimensional Coordination Polymer Based on Cadmium(II), N,N′-(1,4-Phenylenedicarbonyl)diglycinate, and 2,2′-Bipyridine: Crystal Structure, Hirshfeld Surface Analysis, and Luminescence Lifetime Properties †

Niels-Patrick Pook

doi:10.3390/solids2040023

Abstract

In recent years, several coordination polymers of different dimensions and metal–organic frameworks were tested and expected to be good candidates for closing the gap between organic and plastic scintillators on the one hand side and inorganic scintillators on the other hand side. In the present work, we report the synthesis and characterization of a novel one-dimensional scintillating coordination polymer based on cadmium(II), N,N′-(1,4-phenylenedicarbonyl)di-glycinate, and 2,2′-bipyridine. Crystals could be obtained from water–methanol solutions and the structure was determined by single-crystal diffraction. The coordination polymer exhibits scintillation under X-ray excitation and laser as well as UV-light induced photoluminescence with fast decay times. Photoluminescence and X-ray excited optical luminescence (XEOL) properties and decay times were performed using a two-dimensional photon counting streak camera system with a time resolution up to 20 ps. The non-covalent interactions and supramolecular assemblies as a potential multiplier of the scintillating effect were investigated with the aid of a Hirshfeld surface analysis. The quality and phase purity of the used crystals and pellets was clarified by powder diffraction and Rietveld refinement.

Highlights

The discovery of X-rays in 1895 by Wilhelm Conrad Roentgen [1]—and the use of barium platino-cyanide and calcium tungstate [2] as fluorescent materials for the proof of X-rays—have paved the way of research and development on inorganic scintillation materials
The reaction of N,N0 -(1,4-phenylenedicarbonyl)diglycine, 2,20 -bipyridine and cadmium(II) nitrate in alkaline solutions leads to a crystalline scintillating one-dimensional coordination polymer
The X-ray crystallography studies revealed 1D zigzag chains which are linked through a multiplicity of noncovalent interactions of classical and non-classical hydrogen bonding, π-π stacking of the electron deficiency aromatic ligands, as well as

Summary

Introduction

The discovery of X-rays in 1895 by Wilhelm Conrad Roentgen [1]—and the use of barium platino-cyanide and calcium tungstate [2] as fluorescent materials for the proof of X-rays—have paved the way of research and development on inorganic scintillation materials. 531) and so the new class of organic scintillation materials was established. Since this pioneering work, a lot of inorganic and organic scintillators (including plastic and liquid) have been synthesized and improved. Scintillators as materials for converting high-energy photons of X-rays, gamma-rays, and for highly-accelerated particles to visible or UV light photons are widely used for radiation detection in particle and high energy physics [4], in dosimetry of ionizing radiation and are very important for medical health care systems and diagnostics applications such as X-ray computed tomography imaging, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) [5]. Scintillating materials are the core elements of gamma-ray detection and X-ray imaging systems in borderline security.

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Results

Conclusion