Gładysiak Andrzej, Nguyen Tu N, Anderson Samantha L, Boyd Peter G, Palgrave Robert G, Bacsa John, Smit Berend, Rosseinsky Matthew J, Stylianou Kyriakos C
Laboratory of Molecular Simulation (LSMO), Institut des Sciences et Ingénierie Chimiques (ISIC), École Polytechnique Fédérale de Lausanne (EPFL Valais Wallis) , Rue de l'Industrie 17, CH-1951 Sion, Switzerland.
University College London , Department of Chemistry, 20 Gordon St., London WC1H 0AJ, U.K.
Inorg Chem. 2018 Feb 19;57(4):1888-1900. doi: 10.1021/acs.inorgchem.7b02761. Epub 2018 Feb 1.
We report the syntheses and structures of five metal-organic frameworks (MOFs) based on transition metals (Ni, Cu, and Zn), adenine, and di-, tri-, and tetra-carboxylate ligands. Adenine, with multiple N donor sites, was found to coordinate to the metal centers in different binding modes including bidentate (through N7 and N9, or N3 and N9) and tridentate (through N3, N7, and N9). Systematic investigations of the protonation states of adenine in each MOF structure via X-ray photoelectron spectroscopy revealed that adenine can be selectively protonated through N1, N3, or N7. The positions of H atoms connected to the N atoms were found from the electron density maps, and further supported by the study of C-N-C bond angles compared to the literature reports. DFT calculations were performed to geometrically optimize and energetically assess the structures simulated with different protonation modes. The present study highlights the rich coordination chemistry of adenine and provides a method for the determination of its protonation states and the location of protonated N atoms of adenine within MOFs, a task that would be challenging in complicated adenine-based MOF structures.
我们报道了基于过渡金属（镍、铜和锌）、腺嘌呤以及二羧酸、三羧酸和四羧酸配体的五种金属有机框架（MOF）的合成与结构。腺嘌呤具有多个氮供体位点，被发现以不同的配位模式与金属中心配位，包括双齿配位（通过N7和N9，或N3和N9）和三齿配位（通过N3、N7和N9）。通过X射线光电子能谱对每个MOF结构中腺嘌呤的质子化状态进行系统研究表明，腺嘌呤可以通过N1、N3或N7被选择性质子化。与氮原子相连的氢原子的位置从电子密度图中确定，并通过与文献报道相比的C-N-C键角研究得到进一步支持。进行了密度泛函理论（DFT）计算，以对不同质子化模式模拟的结构进行几何优化和能量评估。本研究突出了腺嘌呤丰富的配位化学，并提供了一种确定其质子化状态以及腺嘌呤质子化氮原子在MOF中的位置的方法，这在复杂的基于腺嘌呤的MOF结构中是一项具有挑战性的任务。
