新穎有機-無機複合鋁/鎵亞磷酸鹽之 合成、結構與性質研究

Syntheses and Characterizations of Novel Organic-Inorganic Hybrid Aluminum/Gallium Phosphites

簡塏旻(Chien, Kai Min)

指導教授 ： 王素蘭

國立清華大學/理學院/化學系/碩士(2016年)

摘要

本論文利用中溫中壓水熱法，成功開發出具有孔洞性之輕質鋁亞磷酸鹽材料A1，其新穎三維有機-無機複合骨架上，具有草酸配位基(C2O42－)及甲酸配位基(HCOO－)，並且擁有二氧化碳氣體吸附性質。此外，為了與過去本實驗室所合成之鎵草酸亞磷酸鹽(NTHU-7)進行結構比較，利用鎵作為金屬中心，成功合成出一系列A1之等結構化合物，分別為A2、A3及A4，其晶體結構皆以單晶X光繞射方法解析，並以粉末X光繞射圖譜鑑定產物樣品純度，再進行其他物理及化學性質的測量。
A1以有機胺pentaethylenehexamine (peha)為模板，化學式為[(H6peha)0.17(H2O)1.5][Al2(HPO3)2(C2O4)(HCOO)]。此結構是由[Al2(HPO3)2]2+四環帶狀無限鏈(double zigzag chain)藉由草酸根離子以bis-bidentate的鍵結方式作為架橋形成一直徑為4.8 Å之一維隧洞；這些一維隧洞再藉由甲酸根離子作為架橋環繞成另一直徑為8.5 Å之一維隧洞。從固態13C NMR圖譜、TGA及EA可知，隧洞中之物質含有H6peha6+及H2O，而由高溫單晶X光繞射實驗結果顯示，升溫至400 K移除結晶水之後，僅較大之隧洞中留有電子雲密度，由此可得知H6peha6+座落於較大的孔隧中。
A1結構與NTHU-7相似，但NTHU-7是以鎵作為金屬中心之奈米小管結構，為了比較兩者於結構上的差異，在A1的反應系統中改用鎵取代鋁，並且嘗試不同有機模板(4,4’-trimethylenedipyridine)，成功合成出A1之等結構化合物A2及A3。然而發現A1-A3的結構中，一維隧洞之間皆有殘留電子雲，從鍵長鍵角推測是甲酸連接在一維隧洞之間，但起始反應條件裡並無加入甲酸，根據文獻顯示，草酸於加熱時會分解出二氧化碳及甲酸，並且由化合物母液測定液態DEPT C-NMR之圖譜得知環境中有大量甲酸，為了更進一步找出證據，避免化合物裡的有機模板於1H NMR圖譜裡與甲酸特徵峰(~8.0 ppm)重疊，利用膽鹼離子choline ion為模板，合成另一等結構化合物A4，並於A4之固態1H NMR可得到甲酸特徵鋒之證據，證實是甲酸將一維隧洞連接起來形成三維結構。
A1與A2都具有二氧化碳吸附性質，在273 K下1 atm吸附量分別為10.48 cm3/g、2.90 cm3/g。A1比A2吸附量高上許多，這是由於A1中心金屬是鋁，密度較A2小而造成此差異。

關鍵字

鋁亞磷酸

並列摘要

In this thesis, a new organic-inorganic hybrid framework, A1, bearing oxalate (C2O42－) and formate (HCOO－) in aluminum phosphite lattice, has been synthesized under mild hydrothermal conditions and showed carbon dioxide adsorption property. The large channels located in the structure of A1 are similar to the nanotubules in the gallium oxalatophosphite of NTHU-7. By replacing gallium for aluminum in the reactions, three isostructures A2, A3 and A4 were produced. All four compounds were characterized by single-crystal X-ray diffraction methods. The sample purity for each of the compounds was confirmed by powder X-ray diffraction before gas sorption and other property measurements.
The chemical formula for A1 was determined to be [(H6peha)0.17(H2O)1.5][Al2(HPO3)2(C2O4)(HCOO)], where peha = pentaethylenehexamine. The hybrid framework consists of [Al2(HPO3)2]2+ 4-ring ladder chains interlinked by oxalate and formate groups into two types of channels, one with 4.8 Å in aperture and the other with 8.5 Å. The template H6peha6+ ions and lattice H2O in structure could not clearly elucidate from single-crystal data but were corroborated by the results of combined solid-state 13C NMR, TGA and EA data. The large template ions should reside in the larger channels and lattice waters in the smaller channels, as confirmed by the results from structure analysis on a high-temperature single-crystal X-ray diffraction data measured at 400 K.
Compound A2, a gallium analogue of A1, is very similar to NTHU-7 in structure, A3 and A4 bear the same hybrid framework as A2 except template ions. In the structures of A1 to A4, residual electron densities were located between the smaller channels that could not be neglected to complete the structure refinements. They were primarily identified as formate groups which connected smaller channels to surround into the larger channels, giving rise to the final 3D structure. DEPT C-NMR data measured from reaction filtrates of A1 to A4 revealed the presence of formate anions, indicating the likelihood of in situ formation during reaction. Solid-state 1H NMR measurements as well confirmed formate groups in the structure.
Gas sorption experiments were conducted on the two analouges A1 and A2. They showed affinity for carbon dioxide but were not high. The CO2 uptakes for A1 and A2 were 10.48 cm3/g and 2.90 cm3/g, respectively. The increased adsorption capacity for A1 should partially attribute to the lower density of Al-analogue.

參考文獻

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