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Abstract

This thesis mainly aims to investigate the influence of side chain modifications on the properties of imine based organic cage compounds. A series of [2+3] isostructural POCs with n-butyl, perfluorinated n-butyl, and partially fluorinated n-butyl groups, is synthesized by precursor modification strategy and the structure-property relationship between the degree of fluorination of the alkyl chains and gas sorption properties for perfluorocarbons (PFCs) is studied in detail. The cage with fluorinated side chains shows excellent selectivities for PFCs over N2 (e.g., SH = 41475 for c-C4F8 vs N2), due to fluorine-fluorine interactions. This strategy extends to introducing n-fluorinated alkyl chains of different lengths from perfluoromethyl to perfluorohexyl into [2+3] POCs. The impact of chain lengths on gas uptakes and selectivities for PFCs, sulphur hexafluoride (SF6), and nitrogen trifluoride (NF3) over not only N2 but also O2 or CO2 is explored. The cage with perfluoropentyl chains displays outstanding selective adsorption properties for these fluorinated gases (F-gases) over N2 or O2, while the cage with perfluorobutyl chains still remained the most selective for F-gases over CO2 (e.g., SH = 19631 for c-C4F8 vs CO2). Moreover, the solid packing of POCs significantly influences gas sorption. [2+3] POC with perfluoromethyl groups exhibits different porous and non-porous polymorphic forms, influenced by crystallographic packing and the orientation of middle flexible phenyl groups in terphenyl units. The specific surface of [2+3] POC can be significantly enhanced by elongated π systems of terphenyl units and the optimization of activation conditions. Lastly, a series of [4+4] truncated tetrahedral nitrogen-rich POCs, synthesized from prochiral tripyrroltrialdehyde and side chain-modified amines, reveals face-oriented polyhedra in the crystalline state through X-ray crystallography.