Solvent effect on ultra-fast intramolecular proton tranfer rate by means of spin-lattice relaxation

通过自旋晶格弛豫溶剂对超快分子内质子转移速率的影响

• 批准号: 12640489
• 负责人: MASUDA Yuichi
• 金额: $ 2.05万
• 依托单位: Ochanomizu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640489/
• 关键词: proton transfe rate; intramolecular hydrogen bond; solvent effect; spin-lattice relaxation; プロトン移動反応

The NMR spin-lattice relaxation was applied to analyze the potential energy surfaces or the geometries of intramolecular hydrogen bonds as well as the proton transfer rates.I. Solvent effect on hydrogen-bond structure.The O-H and N-H bond distances respectively for dibenzoylmethane (DBM) and N, N'-diphenyl-6-aminofulvene-1-aldimine (PALDIM) were determined in several solvents by the measurements of the ^1H and the ^<15>N spin-lattice relaxation times caused by the magnetic dipolar interaction with the ^<17>O nucleus or the ^<15>N-H proton. The NH bond distance of PALDIM increased in 0.05 A in acetonitrile than that in carbon tetrachloride. In the case of the OH distance of DBM, 0.04 A increase in DMSO was observed whereas no significant change was observed in CCI4 and acetonitrile. These trend is different from that predicted by a quantum mechanical calculation regarding solvent as dielectric continuum. The interaction between the hydrogen -bonding proton and the electron donor site of … More the solvent molecule is probably important to elongation of the X-H distances.II. Proton transfer rate constant of benzoic acid dimmerThe OH proton spin-lattice relaxation times caused by the magnetic dipolar interaction with the ^<17>O nucleus were determined in hydrocarbon mixture with wide range viscosity. In the high viscosity solvents the observed relaxation rates was different from those calculated only considering the reorientational motion of the dimmer as the fluctuation of the magnetic interaction. The difference was attributed to the contribution of the proton jumping between the two oxygen atoms. The estimated rate was 5x10^9 s^<-1> at 298 K and was much slower than that expected in the crystalline state in spite of the 60 - 80 kJ mol^<-1> of the driving force for the proton transfer in the crystal. The present result is rather better coincidence with the tunnel splitting by an abinitio MO calculation result for formic acid dimmer, ca. 3x 10_8 s^<-1> if one considers a stabilization of the charge delocalization on the carboxyl group in the benzoic acid by the resonance effect. Less

用核磁共振自旋-晶格弛豫方法分析了分子内氢键的势能面或几何构型以及质子转移速率对氢键结构的影响.通过测量磁偶极与^&lt；17&gt；O核或^&lt；17&gt；O核或^&lt；15&gt；N-H质子。PALDIM在乙腈中的NH键距比在四氯化碳中增加了0.05A。在DBM的OH距离的情况下，观察到DMSO增加了0.04A，而CCI4和乙腈没有显著变化。这些趋势不同于将溶剂视为介电连续体的量子力学计算所预测的结果。氢键质子与…电子给体位置的相互作用溶剂分子可能是延长X-H距离的重要因素。II.苯甲酸二聚体的质子转移速率常数测定了在大范围粘度的碳氢混合物中，由于磁偶极作用而引起的氢质子自旋-晶格驰豫时间。在高粘度溶剂中，观察到的驰豫速率与只考虑磁相互作用涨落的微米重定向运动计算的驰豫速率不同。这种差异归因于两个氧原子之间的质子跳跃的贡献。298K时估算的质子转移速率为5×10~(-9)S^~(-1)，虽然晶体中质子转移的驱动力为60~80kJ·mol~(-1)~(-1)，但仍远低于晶态时的预期速率。如果考虑共振效应对苯甲酸中羧基电荷离域的稳定作用，本文的结果与甲酸二聚体约3×10~8 S^~(-1)的从头算隧道分裂计算结果符合得较好。较少

项目成果

H.Hosoi: "ESR and NMR Study of Intramolecular Electron Transfer Rates of 1,3-Dinitrobenzene Radical Anion in Solution. An Examination of Coexisting lons and Solvent Effect"J. Mol Liq.. 71. 397-404 (2000)

H.Hosoi：“溶液中 1,3-二硝基苯自由基阴离子的分子内电子转移速率的 ESR 和 NMR 研究。共存离子和溶剂效应的检查”J。

H. Hosoi: "ESR and NMR Study of Intramolecular Electron Transfer Rates of 1, 3- Dinitrobenzene Radical Anion in Solution. An Examination of Coexisting lons and Solvent Effect"J. Mol Liq.. 71. 397-404 (2000)

H. Hosoi：“溶液中 1, 3-二硝基苯自由基阴离子的分子内电子转移速率的 ESR 和 NMR 研究。共存离子和溶剂效应的检查”J。

Y.Masuda: "Solvent Effect on Rotational Relaxation Time of Ammonium Ion"J.Phys.Chem.B. 106(印刷中). (2001)

Y.Masuda：“溶剂对铵离子旋转弛豫时间的影响”J.Phys.Chem.B. 106（出版中）。

Y.Masuda: "Solvent effect on rotational relaxation time of ammonium ion"J. Phys. Chem. A. 105. 2989-2998 (2001)

Y.Masuda：“溶剂对铵离子旋转弛豫时间的影响”J。

H.Hosoi: "ESR and NMR Study of Intramolecular Electron Transfer Rates of 1,3-Dinitrobenzene Radical Anion in Solution. An Examination of Coexisting Ions and Solvent Effect"J.Mol.Liquid. 75. 401-410 (2000)

H.Hosoi：“溶液中 1,3-二硝基苯自由基阴离子的分子内电子转移速率的 ESR 和 NMR 研究。共存离子和溶剂效应的检查”J.Mol.Liquid。