Synthesis,structures And H/D Isotope Effect Of Organic Salt Compounds With O-H···O Hydrogen Bonds

Deuteration is a chemical tool to provide minimal modification of molecules by replacing a protium atom(H)with a deuterium(D).Deuteration of a hydrogen bond can cause geometric changes in the hydrogen bond,known as geometric H/D isotope effect(GIE).Understanding the GIE on global structures and bulk properties is of great importance to study structure-property relationships of hydrogen-bonded systems.In this thesis,a series of organic salts based on the monoanion of 2,3,5,6-tetrafluoroterephthalic acid was synthesized.Most of the compounds show characteristic hydrogen-bonded chain structures via short O-H?O hydrogen bonds between carboxyl and carboxylate groups.Through deuteration,the H/D isotope effect on the structures and dielectric responses were investigated.The main content of the thesis consists of two parts:Part I:16 compounds,(C₅H₁₄N)?(C₈HF₄O₄)(1)?(C₉H₂₂N)?(C₈HF₄O₄)(2)?(C₅H₆N)?(C₈HF₄O₄)(3)?(C₆H₈N)?(C₈HF₄O₄)(4)?(C₆H₈N)?(C₈HF₄O₄)(5)?(C₆H₈N)?(C₈HF₄O₄)(6)?(C₂H₈N)?(C₈HF₄O₄)(7)?(C₄H₁₂N)?(C₈HF₄O₄)(8)?(C₅H₁₄N)?(C₈HF₄O₄)(9)?(C₄H₁₂NO)?(C₈HF₄O₄)(10)?(C₃H₅N₂)?(C₈HF₄O₄)(11)?(C₃H₅N₂)?(C₈HF₄O₄)(12)?(CH₆N)?(C₈HF₄O₄)(13)?(C₆H₁₆N)?(C₈HF₄O₄)(14)?(C₆H₈N)?(C₈HF₄O₄)(H₂O)(15)and(C₄H₁₂N)?(C₈HF₄O₄)?(H₂O)(16),were synthesized based on tetrafluoroterephthalic acid and organic amines.Their crystal structures and dielectric properties were studied.The H/D isotope effect on crystal structures was further studied for 1-12 and a positive geometric isotope effect was confirmed.Part II:(CH₅N₂)?(C₈HF₄O₄)(17)and(C₇H₁₆N)?(C₈HF₄O₄)(18)were prepared.The crystal structures and dielectric properties of the two compounds were reported and the H/D isotope effect on crystal structures and dielectric properties was further investigated.Compound 17exhibits a reversible dielectric transition at low temperatures and H/D isotopic substitution results in a new polymorph.Compound 18 showed no dielectric properties,but the H/D isotope substitution results in a new polymorph.