The density functional theory (DFT) calculations at B3LYP/6-31 + G(d,p) level were performed for a series of new 2,4,6-cycloheptatriene-1-imine scaffolds which have potential to introduce as organosuperbases. In the present study, we have exploited the 2,4,6-cycloheptatriene-1-imines which strategically substituted at 2 and 7 positions by two potential anchoring arms having lone pair possessing atoms. The designed organic superbases were found to have the higher basicity than the benchmarked molecule, 1,8-bis(dimethylamino)-naphthalene. The proposed superbase B14 bearing guanidine and aniline groups possesses the highest proton affinity value as 1143.8 kJ mol −1 . The protonation enthalpy, Gibbs free energy, harmonic oscillator model of aromaticity (HOMA), and nucleus-independent chemical shift (NICS) were used for the basicity comparison. After the protonation of the designed molecules, the positive charge on the conjugate acid is expected to be delocalized in the cycloheptatriene ring and led to its aromatization. The results indicate that the HOMA and NICS values of the ring in the conjugate acid are strongly elevated. On the other hand, very strong intramolecular hydrogen bonding is formed after protonation. These two factors enhance the stability of the conjugate acids and thereby increase the basicity of the designed molecules.

中文翻译：

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通过使用 2,4,6-环庚三烯-1-亚胺支架，利用芳香性和分子内氢键来定制有机超碱

B3LYP/6-31 + G(d,p) 水平的密度泛函理论 (DFT) 计算是针对一系列新的 2,4,6-环庚三烯-1-亚胺支架进行的，这些支架有可能作为有机超碱引入。在本研究中，我们开发了 2,4,6-环庚三烯-1-亚胺，它在 2 和 7 位被两个具有孤对原子的潜在锚定臂战略性取代。发现设计的有机超强碱比基准分子 1,8-双（二​​甲氨基）-萘具有更高的碱度。所提出的带有胍和苯胺基团的超强碱 B14 具有最高的质子亲和值，为 1143.8 kJ mol -1 。质子化焓、吉布斯自由能、芳香性谐振子模型 (HOMA) 和与核无关的化学位移 (NICS) 用于碱度比较。在设计的分子质子化后，共轭酸上的正电荷有望在环庚三烯环中离域并导致其芳构化。结果表明共轭酸中环的 HOMA 和 NICS 值显着升高。另一方面，质子化后会形成非常强的分子内氢键。这两个因素增强了共轭酸的稳定性，从而增加了设计分子的碱性。质子化后形成非常强的分子内氢键。这两个因素增强了共轭酸的稳定性，从而增加了设计分子的碱性。质子化后形成非常强的分子内氢键。这两个因素增强了共轭酸的稳定性，从而增加了设计分子的碱性。