Barić Danijela
Department of Physical Chemistry, Rud̵er Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
ACS Omega. 2019 Sep 4;4(12):15197-15207. doi: 10.1021/acsomega.9b02087. eCollection 2019 Sep 17.
New neutral organic superbases with 1-azaazulene(s) as a molecular backbone are computationally designed, employing two basic substituents: dimethylaminocyclopropen-imines (CPI) and dimethylaminocyclopropeniminophosphazenes (CPI-P). Their proton affinities, gas basicities, and p values in acetonitrile are obtained using density functional theory. Azaazulenes substituted with CPI have a computed PA in the gas phase ranging between 272.9 and 306.8 kcal mol, with p values in acetonitrile between 28.8 and 36 units. The substitution with the CPI-P group resulted in even stronger superbases, with a PA from 296.5 to 335.2 kcal mol and corresponding p values from 33.9 to 50 units. This exceptionally strong thermodynamic basicity is accompanied by very high kinetic basicity as well; contrary to typical proton sponges, the release of a proton from the conjugate superbase does not demand high activation energy. Because synthetic routes for both substituents and azaazulenes are already known, newly designed superbases represent suitable targets for synthesis and application.
以1-氮杂薁为分子骨架的新型中性有机超强碱通过计算设计而成，采用了两种碱性取代基：二甲基氨基环丙烯亚胺（CPI）和二甲基氨基环丙烯亚胺磷腈（CPI-P）。利用密度泛函理论获得了它们在乙腈中的质子亲和力、气相碱度和p值。被CPI取代的氮杂薁在气相中的计算质子亲和力在272.9至306.8千卡/摩尔之间，在乙腈中的p值在28.8至36个单位之间。用CPI-P基团取代产生了更强的超强碱，质子亲和力在296.5至335.2千卡/摩尔之间，相应的p值在33.9至50个单位之间。这种异常强的热力学碱性也伴随着非常高的动力学碱性；与典型的质子海绵相反，共轭超强碱释放质子不需要高活化能。由于取代基和氮杂薁的合成路线已经为人所知，新设计的超强碱是合成和应用的合适目标。
