A gel aging effect in the synthesis of open-framework gallium phosphates: structure solution and solid-state NMR of a large-pore, open-framework material.
A gel aging effect in the synthesis of open-framework gallium phosphates: structure solution and solid-state NMR of a large-pore, open-framework material.
复制标题
DOI：
10.1039/c7dt03709k
复制
发表时间：
2017-12-12
期刊：
影响因子：
--
通讯作者：
Walton RI
中科院分区：
文献类型：
--
作者：
Broom LK;Clarkson GJ;Guillou N;Hooper JE;Dawson DM;Tang CC;Ashbrook SE;Walton RI
凝胶前体的历史影响磷酸镓结晶中的所得产物，从而允许14环通道结构的隔离。模板化沸石类似物GaPO-34（CHA结构类型）从凝胶前体Ga2O3：2H3PO4：1HF：1.7SDA：70H2O（其中SDA =结构导向剂）结晶，在170 ℃下使用吡啶或1-甲基咪唑作为SDA和差结晶的ε-Ga2O3或γ-Ga2O3之一作为镓前体水热处理24小时。如果相同的凝胶搅拌时间短于2小时，但在相同的水热条件下处理，则第二相结晶，不含GaPO-34。如果使用β-Ga_2O_3作为试剂，则发现仅第二相结晶，而与凝胶老化时间无关。我们表示为GaPO-34A的竞争相已经使用同步加速器粉末X射线衍射对吡啶材料GaPO-34A（pyr）进行结构表征，并使用单晶X射线衍射对1-甲基咪唑材料GaPO-34A（mim）进行结构表征。GaPO-34 A（pyr），P1，a = 10.22682（6）π，B = 12.09585（7）π，c = 13.86713（8）π，α = 104.6531（4）°，β = 100.8111（6）°，γ = 102.5228（6）°，含有7个独特的镓位和6个磷位，实验式为[Ga7P6O24（OH）2F3（H2O）2]·2（C5NH6）。GaPO-34 A（mim）是同构的，但被建模为半体积晶胞，P1，a = 5.0991（2）°，B = 12.0631（6）°，c = 13.8405（9）°，α = 104.626（5）°，β = 100.346（5）°，γ = 101.936（4）°，其中镓和桥接氟化物部分占据和两个部分占据SDA位点。固态31 P和71 Ga NMR光谱证实了GaPO-34 A的结构复杂性，信号来自多个Ga和P位点的重叠线形，而1H和13 C固态NMR光谱证实了质子化SDA的存在，并提供了SDA中无序的证据。质子化的SDA位于14环一维通道中，从SDA氮到骨架氧的距离推导出氢键。在研究SDA去除的热处理后，发生结构塌陷，这可能是由于在所制备的材料中存在大量桥接氢氧化物和氟化物，以及存在不等量的镓和磷。
History of gel precursors affects the resulting product in gallium phosphate crystallisation allowing isolation of a 14-ring channel structure. The templated zeolite-analogue GaPO-34 (CHA structure type) crystallises from a gel precursor Ga2O3 : 2H3PO4 : 1HF : 1.7SDA : 70H2O (where SDA = structure directing agent), treated hydrothermally for 24 hours at 170 °C using either pyridine or 1-methylimizadole as SDA and one of either poorly crystalline ε-Ga2O3 or γ-Ga2O3 as gallium precursor. If the same gels are stirred for periods shorter than 2 hours but treated under identical hydrothermal conditions, then a second phase crystallises, free of GaPO-34. If β-Ga2O3 is used as a reagent only the second phase is found to crystallise, irrespective of gel aging time. The competing phase, which we denote GaPO-34A, has been structurally characterised using synchrotron powder X-ray diffraction for the pyridine material, GaPO-34A(pyr), and using single-crystal X-ray diffraction for the 1-methylimiazole material, GaPO-34A(mim). The structure of GaPO-34A(pyr), P1, a = 10.22682(6) Å, b = 12.09585(7) Å, c = 13.86713(8) Å, α = 104.6531(4)°, β = 100.8111(6)°, γ = 102.5228(6)°, contains 7 unique gallium sites and 6 phosphorus sites, with empirical formula [Ga7P6O24(OH)2F3(H2O)2]·2(C5NH6). GaPO-34A(mim) is isostructural but is modelled as a half volume unit cell, P1, a = 5.0991(2) Å, b = 12.0631(6) Å, c = 13.8405(9) Å, α = 104.626(5)°, β = 100.346(5)°, γ = 101.936(4)°, with a gallium and a bridging fluoride partially occupied and two partially occupied SDA sites. Solid-state 31P and 71Ga NMR spectroscopy confirms the structural complexity of GaPO-34A with signals resulting from overlapping lineshapes from multiple Ga and P sites, while 1H and 13C solid-state NMR spectra confirm the presence of the protonated SDA and provide evidence for disorder in the SDA. The protonated SDA is located in 14-ring one-dimensional channels with hydrogen bonding deduced from the SDA nitrogens to framework oxygen distances. Upon thermal treatment to investigate SDA removal, structure collapse occurs, which may be due the large number of bridging hydroxides and fluorides in the as-made material, and the unequal amounts of gallium and phosphorus present.
登录
查看更多内容
影响因子：
15
作者：
Francis, RJ;O'Brien, S;Férey, G
通讯作者：
Férey, G
影响因子：
15
作者：
Mellot-Draznieks, C;Girard, S;Férey, G
通讯作者：
Férey, G
影响因子：
2.6
作者：
Bhalla, Rajiv;Burt, Jennifer;Reid, Gillian
通讯作者：
Reid, Gillian
影响因子：
4
作者：
Bhalla, Rajiv;Levason, William;Zhang, Wenjian
通讯作者：
Zhang, Wenjian
影响因子：
2.6
作者：
Birnara, Christiana;Kessler, Vadim G.;Papaefstathiou, Giannis S.
通讯作者：
Papaefstathiou, Giannis S.