Construction of a bifunctional Zn(ii)–organic framework containing a basic amine functionality for selective capture and room temperature fixation of CO2†,Inorganic Chemistry Frontiers

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Construction of a bifunctional Zn(ii)–organic framework containing a basic amine functionality for selective capture and room temperature fixation of CO2†
Inorganic Chemistry Frontiers ( IF 6.1 ) Pub Date : 2019-09-20 , DOI: 10.1039/c9qi01058k
Rajesh Das _{1,

2,

3,

4} , Sandeep Singh Dhankhar _{1,

2,

3,

4} , C. M. Nagaraja _{1,

2,

3,

4}

Affiliation

Selective carbon capture and utilization (CCU) as a C1 feedstock for the synthesis of value-added chemicals under ambient conditions catalyzed by porous MOFs constitutes one of the most promising solutions to mitigate the growing CO₂ concentration in the atmosphere. Consequently, the synthesis of a novel 3D, microporous, bifunctional Zn(II)–organic framework, {[Zn₂(TDC)₂(DATRZ)]·(3H₂O)·(DMF)}_n (Zn-DAT) (where TDC = 2,5-thiophene dicarboxylate ion and DATRZ = 3,5-diamino-1,2,4-triazole), was achieved using a mixed ligand strategy. Single crystal X-ray structural analysis of the MOF revealed the presence of a 3D microporous structure with two types of 1D channels of dimensions 12.5 × 8.7 Å² and 7.0 × 4.8 Å² along the crystallographic c- and b-axes, respectively. The presence of basic –NH₂ functionalized pores in Zn-DAT induces a selective adsorption property of CO₂ with a high heat of adsorption (Q_st) value of 39.5 kJ mol⁻¹ which is supported by a theoretically computed binding energy (BE) of 40.9 kJ mol⁻¹. Interestingly, the Q_st value observed for Zn-DAT is about 8 kJ mol⁻¹ higher than that of the analogous MOF {[Zn₂(TDC)(TRZ)₂]·(DMA)·(MeOH)}_n (Zn-TAZ) containing the 1,2,4-triazole (TAZ) linker, which highlights the critical role of –NH₂ groups in enhancing the interaction energy for CO₂. The significantly high value of Q_st can be attributed to the stronger interaction of the acidic CO₂ molecule with the basic –NH₂ groups present in the 1D channels of the Zn-DAT MOF. Furthermore, the presence of both Lewis acidic Zn²⁺ ions and basic –NH₂ groups resulted in the Zn-DAT MOF as an efficient heterogeneous catalyst for chemical fixation of CO₂ into cyclic carbonates under mild conditions at RT. Herein, we report a rare example of porous MOFs for the capture and utilization of CO₂ at RT and the influence of basic –NH₂ groups on the high value of Q_st and catalytic conversion of carbon dioxide.

中文翻译：

双官能的Zn（施工II包含用于选择性捕获和CO的室温下固定碱性胺官能团） -有机构架₂†

选择性碳捕获和利用（CCU）作为在多孔MOF催化下在环境条件下合成增值化学品的C1原料，是缓解大气中不断增长的CO ₂浓度的最有希望的解决方案之一。因此，合成了一种新型的3D，微孔，双功能Zn（II）-有机骨架，{[Zn ₂（TDC）₂（DATRZ）]·（3H ₂ O）·（DMF）} _n（Zn-DAT）（其中TDC = 2,5-噻吩二羧酸根离子，而DATRZ = 3,5-二氨基-1,2,4-三唑）是使用混合配体策略实现的。在MOF的单晶X-射线结构分析显示一个三维微孔结构的存在下用两种类型的尺寸12.5×8.7埃的1D通道²和7.0×4.8埃²沿晶体Ç -和b分别-axes。Zn-DAT中碱性-NH ₂官能化孔的存在诱导了具有29.5 kJ mol ^-1的高吸附热（Q _st）值的CO ₂的选择性吸附特性。通过理论计算的40.9 kJ mol ^-1的结合能（BE）来支持。有趣的是，Q _ST为观测值的Zn-DAT为约8千焦摩尔^-1比类似的MOF的较高{[锌₂（TDC）（TRZ）₂ ]·（DMA）·（甲醇）} _Ñ（含有Zn TAZ）含有1,2,4-三唑（TAZ）接头，其中突出-NH中的关键作用₂基团在增强的相互作用能量的CO ₂。Q _st的极高值可归因于酸性CO ₂的较强相互作用Zn-DAT MOF的1D通道中存在带有碱性–NH ₂基团的分子。此外，路易斯酸性Zn ²⁺离子和碱性-NH ₂基团的存在导致Zn-DAT MOF作为在室温下温和条件下将CO ₂化学固定为环状碳酸酯的有效多相催化剂。在这里，我们报告了一个罕见的多孔MOF实例，用于在RT下捕获和利用CO ₂以及碱性-NH ₂基团对Q _st的高值和二氧化碳的催化转化的影响。

更新日期：2020-01-14

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