Synthesis And Characterization Of The Organically Templated Borates And Phosphates

Inorganic-organic hybrid materials refer to the combination of inorganic and organic molecules. They are bonded with each other to make the materials achieve molecular composite level. It has proved that inorganic-organic hybrid materials are important in the molecule engineering and have potential applications in catalysis, sorption, separation, magnetism, photochemistry, energy storage, biochemistry and medicine. Borate and phosphate materials have been a research field with rapid expansion in the past decades, mainly because of their rich structural chemistry and important practical applications as second harmonic generation optical materials. Therefore, it is believed that exploring inorganic-organic hybrid borates and phosphates is significant for searching for novel functional materials.In this thesis, four novel organically templated borates have been synthesized under mild solvothermal conditions or by using molten boric acid as a synthetic medium. Besides, we have synthesized two inorganic-organic hybrid phosphates by solution method. The crystal structures have been determined from single-crystal X-ray diffraction data and further characterized by FT-IR spectrum, element analysis, SHG, and simultaneous DTA-TG.(1) Two new inorganic-organic hybrid tetradecaborates, [(C₂H₁₀N₂)]₂[B₁₄O₂₀(OH)₆] (1) and [(C₈H₁₄N₂)]₂[B₁₄O₂₀(OH)₆] (2) have been synthesized in the presence of ethylenediamine and 1,3-Bis(aminomethyl)benzene acting as structure-directing agent respectively. Compound 1 is composed of [C₂H₁₀N₂]²⁺ cations and large isolated [B₁₄O₂₀(OH)₆]^4- polyborate anions. The borate FBBs (Fundamental Building Blocks) feature one 8-membered ring and six 3-membered rings. The anionic units, [B₁₄O₂₀(OH)₆]^4-, are interlinked via hydrogen bonding to form a 3D supramolecular network containing large channels, in which the protonated [C₂H₁₀N₂]²⁺ cations are located. Compound 2 consists of isolated [B₁₄O₂₀(OH)₆]^4- polyborate anions and [(C₈H₁₄N₂)]²⁺ cations.(2) Two new inorganic-organic hybrid pentaborates, [C₈H₂₂N₄][B₅O₆(OH)₄]₂ (3) and [C₄H₇N₂][B₅O₆(OH)₄] (4) have been synthesized in the presence of triethylenetetramine and 1-methylimidazole acting as structure-directing agent respectively. Both 3 and 4 contain [B₅O₆(OH)₄]^–, which form a 3D structure containing large channels via hydrogen bonding, in which the protonated [C₈H₂₂N₄]²⁺ cations are intercalated. In compound 3, triethylenetetramine is cyclized and forms the protonated 1,4-bis(2-ammoniomethyl)piperazine cation under synthetic conditions. (3) Two inorganic-organic hybrid phosphates, [C₆H₉N₃O₂][HPO₄] (5) and [(C₇H₆N₃O₂)]₂[HPO₄]·2H₂O (6) have been synthesized by solution method. Compound 5 consists of [C₆H₉N₃O₂]²⁺ cations and [HPO4]2- anions. A 3D supramolecular network is formed through hydrogen-bond system. Compound 5 crystallizes in the monoclinic system with space group Pn (No. 7). It exhibits nonlinear optical properties and its SHG coefficient is about 0.67 times as large as that of KDP (KH₂PO₄). The crystal structure of compound 6 is composed of two [(C₇H₆N₃O₂)]⁺ cations, one [HPO₄]^2- anion and two H2O molecules. The crystal structure is stabilized by intermolecular hydrogen bonds andπ–πstacking interactions.