Non-empirical descriptors of sub-molecular polarity and dispersive interactions in reversed-phase HPLC

Benchmarking of Computational Methods for Creation of Retention Models in Quantitative Structure–Retention Relationships Studies

“…This possibly means that higher levels of theory used for the geometry optimization of new molecules will not reduce any error associated with the weighting used for WHIM descriptors. As another example, Kaliszan and Hartwick used a semiempirical method (CNDO/2) to derive descriptors for total energy, excess charge, and the energy of the lowest unoccupied molecular orbital of a molecule. CNDO/2 was also used for the topological index descriptors .…”

“…CNDO/2 was also used for the topological index descriptors . Kaliszan mentions that the deviation between calculated and observed retention factors of molecules in his study may be due to the error in the SE calculations, or due to assumptions made about standard geometries and bond lengths …”

Expanding Antineoplastic Drugs Surface Monitoring Profiles: Enhancing of Zwitterionic Hydrophilic Interaction Methods

“…Among these charge descriptors, there are the total absolute charge Qtot and the total squared charge Q2, which are measures of molecular polarity, and the topographic electronic descriptor TE2 [37,38], which is the sum of the absolute differences between atomic charges over all pairs of bonded atoms. On the contrary, the descriptors that most determine PC3 (i.e., the maximum negative charge qnmax, the hydrophilic factor Hy [36] and the submolecular polarity parameter SPP [36]) encode electronic properties that rely on the presence of specific atom types or groups in the molecule.…”

“…(2) the 3D atomic coordinates of each molecular structure were calculated by structure embedding using the ETKDG method [28]; (3) the molecular geometry was optimized in the RDKit module [29] by the MMFF94 [30] force field with 200 iterations, selecting the minimum energy conformation; (4) the atomic partial charges were computed by means of the web-based tool Atomic Charge Calculator [31] using the B3LYP/6-311G/NPA approach [32]. The structural and physicochemical features of chemicals were then encoded through the following 18 molecular descriptors: molecular weight (MW), hydrophilic factor (Hy) [33], total topological polar surface area (TPSA) [34] and 15 charge descriptors (qpmax, qnmax, Qpos, Qneg, Qtot, Qmean, Q2, RPCG, RNCG, SPP, TE1, TE2, PCWTE1, PCWTE2, LDI) [35][36][37][38][39][40][41]. These descriptors were selected on the basis of the literature review and calculated by the software Dragon 7 [42].…”

Antioksidan etkili melatonin türevi bazı bileşiklerin yapı-etki ilişkileri: structure-activity relationships of antioxidant effective some melatonin derivatives

“…Bileşiğin biyolojik etkisine bakıldığında LP üzerinde çok düşük bir inhibisyona (% 6) sahip olduğu görülmektedir. Bu durumda akla ilk gelen zincirdeki düşük elektron yoğunluğunun biyolojik aktivitede negatif bir faktör olup olmadığıdır, ancak, aynı zincir yapısına sahip diğer bileşiklere (2,8,9,11,12,(20)(21)(22)(23)(24) bakıldığında bu bölgede elektron yoğunluğunun 14 no'lu bileşiğe oranla daha yüksek olduğu ve bu diğer bileşiklerin değişken biyolojik aktivite gösterdikleri görülmektedir. Dolayısıyla, 14 no'lu bileşikte görülen amid yapısındaki elektron şiddeti, biyolojik aktivite üzerinde etkili bir özellik olamamaktadır.…”