Syntheses And Characterization Of Open-framework Metal Phosphites

Microporous inorganic materials have wide applications in catalysis,absorption, separation,ion-exchange and host-guest assemblies due to their unique regular pore structures.Rational design and synthesis of new microporous compounds,as well as the development of new synthetic routes have attracted much attention in microporous materials chemistry.Open framework metal phosphates have been extensively pursued for their structural diversities and potential applications.Recently,replacing tetrahedral phosphate groups by pseudo pyramidal phosphite units has experienced dramatic expansion for constructing novel microporous crystals.Many metal phosphite compounds with novel open-structures have been isolated,including 0-D clusters,1-D chains,2-D layers and three-dimensional open-framework structures. Much attention was paid to zinc phosphites for their compositional and structural versatilities.Up to date,more than 30 novel open-structured zincophosphites have been hydrothermally synthesized by using various organoamine or metal complexes as templates.Furthermore,transition metal phosphites have also been considerably explored.Phosphite compounds of V,Fe,Co,Mn,Zn and Cr with their various properties have been reported.However,open-framework indium phosphites are seldom reported.This thesis focused on designed synthesis of metallophosphite open-structures with large pores,new compositions and novel topologies.By using various organoamine as templates,the syntheses and structures of zincophosphites and its doping derivatives and indium phosphite were studied.Doping induced structure variation of zincophosphites was also discussed.As the results,five new metal phosphites open-structures were isolated.1.By using 1,4-diazabicyclo[2.2.2]octane(DABCO)as template,a novel 3-D zincophosphite(C₆N₂H₁₄)·[Zn₃(HPO₃)₄](TJPU-5)has been synthesized under mild hydrothermal conditions.The three-dimensional open-structure is constructed by connecting ZnO₄ tetrahedral and HPO₃ pseudo pyramids to form 4,8-membered ring channels.The channel spaces are partially occupied by diportonated DABCO cations that bond to the framework via strong H-bond. More interestingly,a new[4⁴8⁸]cages was first discovered in TJPU-5.2.Two new open-framework zincophosphites,[H₂CHBMA][Zn_2.34Fe_0.66(HPO₃)₄] (TJPU-6Fe)and[H₂CHBMA][Zn_2.1Co_0.9(HPO₃)₄](TJPU-6),have been hydrothermally prepared by using 1,3-cyclohexane bis(methylamine)(CHBMA) as template.Single crystal structure refinement revealed that these two compounds are isostructural materials.The structures of two compounds are built up by propagating a new second building units(SUB)of furcated hexagonal square(6=1)to form the three-dimensional open frameworks with 12-ring channels.Due to the up and down aligned SBU along a direction,the sheet structure in bc plane stacks in ABAB style that generate 12-ring zigzag apertures running along the a axis.Astonishingly,the methylamine groups of CHBMA molecules in THPU-6Fe and TJPU-6 sit in trans-conformation in the channels and bond to the inorganic frameworks through complex H-bonds.3.A novel three-dimensional manganese zinc phosphatophosphite [H₂CHBMA][Zn₂Mn_0.5(PO₄)(HPO₃)₂]·H₂O(TJPU-3Mn)with extra-large 20-ring channels has been isolated in the presence of 1,3-cyclohexane bis(methylamine) (CHBMA)under hydrothermal conditions.It is the first structure analogue to the famous aluminophosphate JDF-20.The connectivities of the MO₄,PO₄ and HPO₃ groups creat a three-dimensional porous architecture with extra-large 20-ring channels intersected by 8-ring channels.The CHBMA cations locate in the channels to banlance the negtive charges of skeleton.Four diprotonated CHBMA cations reside in each 20-ring window.The alkyl groups of these cations extend into the hollow space of the 20-ring channel with their -NH₃⁺ groups forming H-bonds with the framework oxygen atoms.More interestingly, the diprotonnated CHBMA cations in the channel are all in cis-conformation. Similar to TJPU-6Fe and TJPU-6,these compounds show a potential for recognition and separation of CHBMA isomers.4.Under mild hydrothermal conditions and using CHBMA as trial structure-directing agent,a new neutral three-dimensional indium phosphite In₂(HPO₃)·3H₂O(TJPU-7)was synthesized and characterized by single crystal structure determnation.The structure is formed by linking InO₆ octahedral and HPO₃ pseudo pyramids form 3-D inorganic framework with intersecting 4-, 8-ring channels.