The Phase Transition Properties Of Molecule Based Diamine Compounds

Phase transition materials of organic salt compounds have been widely investigated in the last three decades due to their natural habit of easy crystal growing and non-heavy metal pollution.In this paper,the properties of phase transitions and dielectric constants of 1,4-diazabicyclo[2.2.2]octane(dabco)based organic salts and co-crystals were studied.The main body of this thesis contains three sections.In the first section,six dabco based organic salt compounds([(H2dabco)(H2O)](ClO4)2(1),[(H2dabco)(H2O)](BF4)2(2),[(Hdabco)(H2O)](PF6)(3),[(H2dabco)(H2O)2](PF6)2(4),[(H2dabco)(H2PO4)3]·H3PO4(5,P21),[(H2dabco)(H2PO4)3]·H3PO4(6,P21/n))were investigated.Compounds 1-3 show reversible phase transitions under the temperature stimulation,while compound 5 displays irreversible phase transition through spontaneous strain release and mechanical grinding.In section two,reversible phase transition and phase transformation double-adjustable compound(BEDABCO)ClO4·H20(7)and its analogs(BEDABCO)Cl04·D20(8),(CEDABCO)ClO4·H20(9)and(BEDABCO)BF4 H20(10)were synthesised and studied(BEDABCO = 1-(2-bromoethyl)-dabco,CEDABCO = 1-(2-chloroethyl)-dabco).It was found that all the compounds exhibit reversible phase transitions owing to the swing-like movement of the water molecules and reversible phase transformation by reversible de/absorbing water molecules.In the last section,three co-crystals((Hdabco)(TU)2(HF2)(11),(H2dabco)(TU)I2(12),(H2dabco)(TU)4(SO4)(13))based on dabco and thiourea(TU)molecule were introduced.In 11 and 13,the dabco cations show two different disordered types,acting as an elevator and a rotator,respectively,while in 12,the TU molecules act as a molecule pendulum.Enough active space is the prerequisite for these compounds to show dynamic-like behaviors.