Dipartimento di Chimica IFM, Università di Torino and NIS, Nanostructured Interfaces and Surfaces Centre of Excellence, Torino, Italy.
Phys Chem Chem Phys. 2012 Jan 14;14(2):987-95. doi: 10.1039/c1cp22897h. Epub 2011 Nov 29.
Continuous Wave (CW), pulse Electron Paramagnetic Resonance (EPR) and pulse Electron Nuclear Double Resonance (ENDOR) spectroscopies, in conjunction with UV-Vis and Infrared (IR) spectroscopies, are used to investigate the chemical reactivity of tetrahedrally coordinated Ti(3+) ions isomorphously substituted in the framework of AlPO-5 towards NH(3) and O(2). The coordination of ammonia to Ti(3+) centres is followed in detail by complementary vibrational and electron magnetic resonance techniques. In particular HYSCORE spectra allow identifying the coordination of two ammonia molecules to Ti(3+) centres resolving the full hyperfine and quadrupole (14)N coupling tensors. The reactivity of the reduced TiAlPO sample towards molecular oxygen is detailed by means of CW-EPR and pulse ENDOR spectroscopy. (17)O(2) is employed, allowing to establish the formation of a "side-on" η(2) O(2)(-)-Ti(4+) electrostatic complex. Pulse ENDOR spectra provide detailed information on the local environment of the formed superoxide radical anion which acts as a paramagnetic probe, providing evidence for Ti-O-Ti oligomeric species.
连续波 (CW)、脉冲电子顺磁共振 (EPR) 和脉冲电子核双共振 (ENDOR) 光谱学，与紫外-可见 (UV-Vis) 和红外 (IR) 光谱学相结合，用于研究四面体配位 Ti(3+) 离子在 AlPO-5 骨架中同晶取代对 NH(3) 和 O(2) 的化学反应性。通过互补的振动和电子磁共振技术详细研究了氨与 Ti(3+) 中心的配位。特别是 HYSCORE 光谱允许通过解析完整的超精细和四极 (14)N 偶合张量来识别两个氨分子与 Ti(3+) 中心的配位。通过 CW-EPR 和脉冲 ENDOR 光谱学详细研究了还原 TiAlPO 样品对分子氧的反应性。使用 (17)O(2)，可以确定“侧接”η(2)O(2)(-)-Ti(4+)静电配合物的形成。脉冲 ENDOR 光谱提供了有关形成的超氧自由基阴离子的局部环境的详细信息，该阴离子作为顺磁探针，为 Ti-O-Ti 低聚物物种提供了证据。
