A series of non-substituted 1,3,5-triaryl-2-pyrazolines and pyrazolines substituted with Fluoro (-F), Chloro (-Cl) and Bromo (-Br) groups at the 3-aryl position were studied. All calculations were done using the conceptual framework of density functional theory. The geometries and reactivity properties were analyzed according to an increase from one to twelve alkyl units in the 5-aryl of 2-pyrazoline ring. In order to be able to apply the particular methodology named KID procedure (for Koopmans in DFT), the KID descriptors were calculated and the results showed that the use of this approximation (Koopmans’ theorem in DFT studies) is feasible. The results for the geometries determined that the increase of the chain with alkyl units does not affect the geometry of the systems. However, the solvation energy also calculated is affected by this increase in the allyl chain length. Due to this, as the chains increases, the solubility of the molecular systems diminishes. The chemical reactivity properties were determined by calculating the descriptors that arise from conceptual DFT and it could be demonstrated that they are not affected by the chain growth. Slight differences were found due to the different halogen substitutions. Finally, it could be observed that all the pyrazolines present an important electrophilic behavior.

Properties changes in relation to the increasing alkyloxy chain length and halogens presence.

中文翻译：

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1,3,5-三芳基-2-吡唑啉骨架共轭主链上不同卤素取代的反应活性与烷氧基链长度增加的关系：概念密度泛函理论研究。

一系列未取代的1,3,5-三芳基-2-吡唑啉和吡唑啉被氟（-F），氯（-Cl）和溴（-Br）基团取代研究了在3-芳基位置上的取代基。所有计算均使用密度泛函理论的概念框架进行。根据2-吡唑啉环的5-芳基中从1到12个烷基单元的增加来分析几何形状和反应性。为了能够应用称为KID过程的特定方法（对于DFT中的Koopmans），计算了KID描述符，结果表明使用这种近似（DFT研究中的Koopmans定理）是可行的。几何结构的结果确定，链上烷基单元的增加不会影响系统的几何结构。但是，烯丙基链长度的这种增加也会影响溶剂化能。因此，随着链的增加，分子系统的溶解度降低。通过计算由概念性DFT产生的描述符来确定化学反应性，并且可以证明它们不受链增长的影响。发现由于卤素取代基的不同而存在细微差异。最后，可以观察到所有的吡唑啉都表现出重要的亲电行为。

性能随着烷氧基链长度的增加和卤素的存在而变化。