To study the relationship between polymorphism and catalytic activities of lanthanide coordination polymers in the cycloaddition reactions of CO₂ with epoxides, the monoclinic and triclinic polymorphs of [Ln^III(NH₃–Glu)(ox)]·2H₂O, where Ln^III = La^III (I), Pr^III (II), Nd^III (III), Sm^III (IV), Eu^III (V), Gd^III (VI), Tb^III (VII), and Dy^III (VIII), NH₃–Glu^– = NH₃⁺ containing glutamate, and ox^2– = oxalate, were synthesized and characterized. Factors determining polymorphic preference, the discrepancy between the two polymorphic framework structures, potential acidic and basic sites, thermal and chemical stabilities, active surface areas, void volumes, CO₂ sorption/desorption isotherms, and temperature-programmed desorption of NH₃ and CO₂ are comparatively presented. Based on the cycloaddition of CO₂ with epichlorohydrin in the presence of tetrabutylammonium bromide under solvent-free conditions and ambient pressure, catalytic activities of the two polymorphs were evaluated, and the relationship between polymorphism and catalytic performances has been established. Better performances of the monoclinic catalysts have been revealed and rationalized. In addition, the scope of monosubstituted epoxides was experimented and the outstanding performance of the monoclinic catalyst in the cycloaddition reaction of CO₂ with allyl glycidyl ether under ambient pressure has been disclosed.

中文翻译：

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镧系-谷氨酸-草酸配位聚合物的多晶型及其对催化活性的影响

_{为了研究镧系配位聚合物在CO 2}与环氧化物环加成反应中的多晶型与催化活性之间的关系，研究了单斜晶型和三斜晶型[Ln ^III (NH ₃ –Glu)(ox)]·2H ₂ O，其中Ln ^III = La ^III ( I )、Pr ^III ( II )、Nd ^III ( III )、Sm ^III (IV )、Eu ^III ( V )、Gd ^III ( VI )、Tb ^III ( VII ) 和 Dy ^III ( VIII )，合成并表征了NH ₃ –Glu ^– = 含有谷氨酸的NH ₃ ⁺和ox ^2– = 草酸。决定多晶型偏好的因素、两种多晶型框架结构之间的差异、潜在的酸性和碱性位点、热稳定性和化学稳定性、活性表面积、空隙体积、CO _{2吸附/解吸等温线以及NH 3}和CO ₂的程序升温解吸都比较呈现。在常压、无溶剂条件下，四丁基溴化铵存在下，通过CO ₂与环氧氯丙烷的环加成反应，评价了两种多晶型物的催化活性，并建立了多晶型物与催化性能之间的关系。单斜催化剂的更好性能已被揭示并合理化。此外，还对单取代环氧化物的范围进行了实验，揭示了单斜晶系催化剂在常压下CO ₂与烯丙基缩水甘油醚环加成反应中的优异性能。