DNTF的核磁表征及理论研究

为了完善3,4-双(4′-硝基呋咱-3′-基)氧化呋咱(DNTF)的核磁表征,采用NMR实验与GIAO-NMR理论计算相结合的方法区分并归属¹³C 和¹⁵N的化学位移。采用二甲基亚砜(DMSO-d₆)、丙酮(Acetone-d₆)和氯仿(CDCl₃)为溶剂,进行了DNTF的一维¹³C NMR和¹⁵N NMR实验,并在DMSO-d₆中获得DNTF的所有核磁信号。采用二维INADEQUATE实验完成了¹³C NMR 的归属。采用高斯09程序,在DFT-B3LYP/6-311+G(2d, p)水平上优化了DNTF结构,用GIAO方法在不同基组上计算了¹³C NMR和¹⁵N NMR的化学位移,计算结果与实验值一致性较好。结果表明,受氧化呋咱环上氧原子O(22)吸电子作用的影响,C(9)与C(13)的化学位移出现较大的差别,与C(13)相比,C(9)出现在高场。

NMR Characterization and Theoretical Investigation of DNTF

In order to optimize the NMR assignment of 3, 4-dinitrofurazanfuroxan (DNTF), a combination of experimental NMR and computational GIAO-NMR techniques was utilized to distinguish the chemical shifts of ¹³C and ¹⁵N. One dimensional (1D) ¹³C and ¹⁵N NMR analyses were performed using DMSO-d₆, acetone-d₆ and CDCl₃ as solvent. All signals of DNTF were found in DMSO-d₆. In the ¹³C NMR, the chemical shifts were assigned by 2D INADEQUATE NMR experiment. Based on the geometry of DNTF optimized at the DFT-B3LYP/6-311+G(2d, p) level by using Guassian 09 program, the ¹³C and ¹⁵N NMR chemical shifts were calculated by GIAO method at different level, which agree with experimental data. Results show that the electro-withdrawing effect of the O(22) in furoxan cycle leads to large ¹³C chemical shift changes of C(9) and C(13), and makes C(9) appear in higher field than C(13).