Design and Synthesis of Fluorinated Porous Molecular Crystals
Hashim, Mohamed I. 1985-
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Porous molecular crystals are an emerging class of porous materials that are built from discrete molecules rather than being polymeric in nature. In this thesis, the effects of the molecular structure of the precursors on the formation of porous solid-state structures were examined. One of the trigonal fluorinated porous molecular crystals displayed aggregation-induced emission and this discovery was studied in more detail. Chapter One, summarizes the research literature that discusses the work and applications conducted on crystalline porous materials. The porous materials that are discussed herein are metal-organic frameworks, covalent organic frameworks, and porous organic molecular crystals that are held together by non-covalent interactions. Chapter Two, discusses the synthetic strategies and methodology utilized in the preparation of six novel fluorinated porous molecular crystal precursors of different geometries. The insights and lessons learned from the successful and failed synthetic attempts are also discussed. Chapter Three, describes the solvothermal synthesis and characterizations of molecular crystals. The gas sorption isotherms and hydrophobic properties of the porous variants are also discussed. Chapter Four, describes the investigations of the fluorescent properties of fluorinated trispyrazole compounds that make up porous molecuclar crystal frameworks. It was found that in a DMF/H2O mixed solvent system one of the compounds displays aggregation-induced emission (AIE), while its iso-structural counterpart does not. The reason for this difference was investigated. Further research conducted on the AIE active compound also led to the discovery that it can discriminate between dicarboxylic acids through assembly induced emissions. In summary, this study the grometry and dimensions of the precursors was varied, resulting in six crystallographically characterized derivatives. Among these derviatives two were found to be porous and posessed surface areas of 903 m2 g⁻1 and 1821 m2 g⁻1. It was also revealed that the rigid trigonal geometry plays a key role in the design and prepararation porous molecular crystals.