【作者】 周丹；

【导师】 于吉红； 徐如人；

【作者基本信息】 吉林大学 ， 无机化学， 2006， 博士

【摘要】 开放骨架结构磷酸铝是微孔晶体材料中一个重要的家族。其中阴离子骨架磷酸铝展现出极为丰富的组成计量比与结构多样性,这主要是源于骨架中存在多种Al和P的配位态,即AlO_n （n = 4,5,6）和P（O_b）_n（O_t）_（4-n） （n = 1,2,3,4）,b为桥氧,t为端氧。固体核磁共振对近程有序敏感,是分析微孔材料的强有力工具。本论文围绕阴离子骨架磷酸铝开展了系统的固体核磁共振研究。在吡啶体系下,我们成功地合成了一种新型三维阴离子骨架磷酸铝微孔化合物（NH₄）₂Al₄（PO₄）₄（HPO₄）·H₂O （AlPO-CJ19）,其Al/P比为4/5。这是第一个具有三种铝的配位态（AlO₄,AlO₅和AlO₆）且所有O原子均与P原子连接的磷酸铝微孔化合物。本文进一步讨论了Al/P比为4/5的所有可能的Al和P的配位状态以及连接方式。本文对一系列具有不同Al/P比与Al和P的配位态的阴离子骨架磷酸铝进行了多种固体核磁共振技术的研究,包括²⁷Al、²⁷Al{³¹P} REDOR、³¹P、²⁷Al→³¹PCP和³¹P{²⁷Al} TRAPDOR技术,得到了²⁷Al/³¹P的化学位移与Al/P的配位态之间的关系。通过²⁷Al、²⁷Al{³¹P} REDOR、³¹P、²⁷Al→³¹P CP和³¹P{²⁷Al} TRAPDOR技术的结合,可以确定Al和P的配位环境。根据开放骨架磷酸铝中Al和P的配位态满足的关系式建立了一种利用固体核磁共振技术确定磷酸铝骨架Al/P比的新方法,这对于理解未知结构的磷酸铝具有重要的意义。本文归纳和总结了归属中性骨架磷酸铝²⁷Al/³¹P NMR信号的方法,进一步探讨了归属阴离子骨架磷酸铝²⁷Al/³¹P NMR信号的方法,并以层状磷酸铝[Al₂P₃O₁₂H]^2-·2[C₆H₁₁NH₃⁺] （UT-4）为例阐述了²⁷Al/³¹P NMR信号的归属。通过固体核磁共振技术对磷酸铝微孔化合物的研究,显示了固体核磁共振在微孔材料研究领域发挥的重要作用。固体核磁共振技术是X射线衍射技术的有效补充,在分析结构、确定骨架元素配位态等方面具有不可替代的作用。更多还原

【Abstract】 Since the first discovery of microporous aluminophosphates AlPO4-n （n denotesa specific structure type）, the synthesis of aluminophosphates has attracted greatattention because of their potential application in catalysis, adsorption, andseparation. The aluminophosphate family displays rich structure chemistry,encompassing neutral zeolite-like open-frameworks and anionic frameworks withthree-dimensional （3D） open-framework, two-dimensional （2D） layer,one-dimensional （1D） chain, and zero-dimensional （0D） cluster structures.In contrast to neutral framework AlPO4-n with an Al/P ratio of exclusively unity,which are constructed from the strict alternation of tetrahedrally coordinated Al and Patoms, anionic framework aluminophosphates show vast structural andcompositional diversities with an Al/P ratio of less than unity, owing to theoccurrence of coordination numbers greater than four for Al atoms and the existenceof terminal P-O bonds. The Al polyhedra include AlO₄, AlO5 and AlO6, and the Ptetrahedra include PO_4b, PO_3bO_t, PO_2bO_2t and PO_bO_3t （with b representing bridgingoxygens and t terminal oxygens）. The diverse linkages of Al polyhedral units and Ptetrahedral units via Al–O–P bonds result in various stoichiometries, includingAlPO4（OH）-, AlP4O169-, AlP2O83-, Al2P3O123-, Al3P4O163-, Al3P5O206-, Al4P5O203-,Al5P6O243-, Al11P12O483-, Al12P13O523-, Al13P18O7215-, and so forth.Although open-framework compounds are highly crystalline and their structuresare often highly symmetrical, there are still difficulties in determining their crystalstructures only by diffraction techniques. When they are microcrystalline withparticle dimensions of only a few micrometers, the application of single-crystaldiffraction analysis is limited. High-resolution solid-state NMR spectroscopy, whichis sensitive to the local ordering and topology of nuclei environments, can givevaluable complementary information about the framework structure, and has beenproven to be an efficient complementary method to X-ray diffraction. It has beenextensively used in the structural investigations of zeolite structures.AlPO-CJ19, with an Al/P ratio of 4/5, has been synthesized solvothermally inthe system of Al（OPri）3?H3PO4?2-aminopyridine?pyridine. Its structure is based onstrictly alternating Al units including AlO4, AlO5 and AlO6 and P tetrahedra includingPO4b and PO3bOH to form a 3D open-framework with 8-MR channels along the [100]direction. Solid-state NMR techniques confirm the single-crystal X-ray diffractionanalysis results. 27Al MAS NMR spectrum indicates four Al signals with the ratio of2AlO4:1AlO5:1AlO6. 31P MAS NMR spectrum presents five tetrahedral P signalswith the ratio of 1:1:2:1. Sixteen kinds of combination of different Al and Pcoordinations are summarized, which may lead to the [Al4P5O20]3-stoichiometry. Upto now, three kinds of combination have been known. It is believed that many morenew aluminophosphates with [Al4P5O20]3-stoichiometry will be continuouslysynthesized.A series of anionic framework aluminophosphates, with different Al/P ratios,have been studied by various solid-state NMR techniques, and the combination of27Al MAS, 27Al{31P} REDOR, 31P MAS, 27Al → 31P CP/MAS NMR, and 31P{27Al}TRAPDOR techniques can provide more detailed structural information on both theAl coordinations （AlO4b, AlO5b, and AlO6b） and P coordinations （PO4b, PO3bOt,PO2bO2t, and PObO3t）. The number of Al （or P） atoms in the second coordinationsphere for P （or Al） atoms can be unambiguously determined by using TRAPDORand REDOR techniques. In terms of the relationship between the coordination statesand Al/P ratios found for open-framework aluninophosphates, a new method todetermine the Al/P ratio of open-framework aluminophosphates based on NMR hasbeen established, which is useful for the understanding of unknownaluminophosphate structures, and this is our principal motivation to determine thecoordinations of Al and P of open-framework aluminophosphates by solid-stateNMR techniques. We are currently developing a computational method to solve thealuminophosphate structure combined with NMR and XRD analyses. The specifiedAl and P units determined by NMR can be assembled by AASBU （automatedassembly of secondary building units） computational method under possible spacegroups suggested by XRD analysis. Solid-state NMR techniques have demonstratedtheir powerful strength in structural investigation of zeolite and relatedopen-framework materials.The methods to assign the 27Al/31P NMR signals of neutral frameworkaluminophosphates have been summarized.On the basis of these, the methods toassign the 27Al/31P NMR signals of anionic framework aluminophosphates have beenstudied. Layer aluminophosphate[Al2P3O12H]2-·2[C6H11NH3+] （UT-4） is presented asan example.Solid-state NMR is a powerful and useful technique for structural identificationof microporous materials. Further, it will be a challenging task to investigate thecrystallization process and phase transformation by advanced NMR techniques.更多还原