Probing the Rotational Dynamics of<i>meso</i>-(2-Substituted)aryl Substituents in A<sub>2</sub>B-Type Subporphyrins
作者:Kota Yoshida、Graeme Copley、Hirotaka Mori、Atsuhiro Osuka
DOI:10.1002/chem.201402778
日期:2014.8.4
A2B‐type B‐methoxy subporphyrins 3 a–g and B‐phenyl subporphyrins 7 a–c,e,g bearing meso‐(2‐substituted)aryl substituents are synthesized, and their rotational dynamics are examined through variable‐temperature (VT) 1H NMR spectroscopy. In these subporphyrins, the rotation of meso‐aryl substituents is hindered by a rationally installed 2‐substituent. The rotational barriers determined are considerably
合成了带有内消旋-(2-取代)芳基取代基的2 B型B-甲氧基亚卟啉3a - g和B-苯基亚卟啉7a - c,e,g,并通过可变温度检查了它们的旋转动力学( VT)1 H NMR光谱。在这些subporphyrins,的旋转内消旋-芳基取代基是由一个合理安装了2位取代基的阻碍。确定的旋转势垒比以前报道的卟啉小得多。旋转激活参数的比较显示出ΔH ≠的可变贡献和Δ小号≠在Δ ģ ≠。所述的2-甲基和2-乙基消旋在subporphyrins -芳基取代基3e中,3 F,和7e中诱导比2 -烷氧基取代基的较大的旋转障碍。由于存在4-二苄氨基基团,能够通过电子稳定共面旋转过渡态的能力降低了3 g和7 g的旋转势垒。B-苯基亚卟啉的旋转势垒小于B-甲氧基亚卟啉的旋转势垒,表明S N 1型杂解对介导的芳基取代基的旋转作用可忽略不计。