Comparison of Different Theory Models and Basis Sets in Calculations of TPOP24N-Oxide Geometry and Geometries of meso-Tetraphenyl Chlorin N-Oxide Regioisomers

Abstract

Results of the comparisons of various density functional theory (DFT) methods with different basis sets for predicting the molecular geometry of TPOP24N-Oxide macrocycle, an oxoporphyrin N-oxide, are reported in this paper. DFT methods, including M06-2X, B3LYP, LSDA, B3PW91, PBEPBE, and BPV86, are examined. Different basis sets, such as 6-31G*, 6-31+G (d, p), 6-311+G (d, p), and 6-311++G (d, p), are also considered. The M06-2X/6-31G* level is superior to all other density functional methods used in predicting the geometry of TPOP24N-Oxide. The geometries of regioisomeric chlorin N-oxide and oxoporphyrin N-oxide are reported using M06-2X/6-31G* method. The geometry effects of oxoporphyrin and chlorin N-oxide regioisomers are increased β-β bond lengths by N-oxidation because the bond overlap index due to charge transfers is decreased. In N-oxidation ring (II, III), angles that include β-β bond length increase as the bond overlap index of β-β bond is decreased by N-oxidation. The potential energy surfaces of chlorin N-oxide and oxoporphyrin N-oxide are explored by M06-2X/6-31G*, and single-point calculations are performed at levels up to M06-2X/6-311++G (d, p). Total and relative energies are then calculated. The results indicate that chlorin 24 N-oxides are more stable than chlorin 22 N-oxides in chlorin N-oxide regioisomers. Moreover, TPOP24N-Oxide is less stable than TPOP22N-Oxide.

Understanding the Interactions of Neptunium and Plutonium Ions with Graphene Oxide: Scalar-Relativistic DFT Investigations

“…In addition, the spin contaminations of all complexes are neglected because of <S 2 > values close to the ideal values of S(S + 1). It has been known that geometries are less sensitive to the size of the basis set, 47 while the corresponding energies can vary significantly with different basis sets. 48 Therefore, single-point calculations and solvation effects at the optimized geometries were also performed for all complexes with the ECP60MWB-SEG valence basis set for actinide atoms and 6-311+G(d, p) basis set for light atoms with the B3LYP functional.…”

Insights into the Mechanism of the Benzoannelated Thieno[3,2-b]furan Halogenation. Importance of HOMO–HOMO Interaction

“…Also, a certain consideration was taken into account choosing an appropriate basis set for the current study. An attempt to choose basis sets 6-311++G(d, p), 6-31+G(d), 6-31G(d, p), and 6-31G(d) for evaluation of reactions of heterocyclic systems with heavy atoms revealed that all basis sets provided almost identical results. − Thus, the 6-31G(d) basis set should be the best compromise between speed and accuracy for reactions involving the interactions with bromine atom. It is worth mentioning that Pople et al have extended the medium basis sets 6-31G and 6-31G(d) for the third-row elements including bromine. , The extended 6-31G basis set has six primitive Gaussians for 1s, 2s, 2p, 3s, and 3p orbitals, and a split-valence pair of three and one primitives for valence orbitals, which are 4s, 4p, and 3d.…”

Synthesis and DFT characterisation of 2-arylamino-1,4-benzoquinone derivatives as potential electron transfer mediators

“…The use of the B3LYP hybrid functional at the DFT level is the most popular choice for treatment of heteroaromatic derivatives which matches well with the experimental observations [24][25][26][27]. The use of 6-311G, 6-31G basis sets accomplished with additional diffuse and polarized functions for the aromatic heterocycles also provided comparable results [28][29][30][31]. In this investigation, the search of a reasonable basis set has been explored for BQ and compounds 2a-f, 3b.…”