Revealing substituent effects on the electronic structure and planarity of Ni-porphyrins

Abstract

Using density functional theory, we have studied the effects on structural and electronic consequences (including HOMO-LUMO energy gaps, vertical ionization potentials (IPv), and vertical electron affinities (EAv)) of the following two factors: (a) meso- and β-substituents acting as inductive donors (CH3), inductive acceptors that are electron-donating through resonance (Br), inductive electron acceptors (CF3), and resonance enabled acceptors (NO2); and (b) complete replacement of pyrrole nitrogens with P-atoms. The principal results of the study are: (1) For the bare Ni-porphyrin, the solvents were found not to affect the HOMO–LUMO gaps but to change the IPv and EAv noticeably. (2) In the series CH3 → Br → CF3 → NO2 the HOMO-LUMO energy gaps, IPv, and EAv increase for both meso- and β-substituents. The ruffling distortion of the porphyrin core is retained, and becomes stronger for the two acceptor groups. In general, effects of meso-substituents on the ruffling distortion of the porphyrin core is more pronounced. (3) Most significantly, complete replacement of pyrrole nitrogens in the NiP with phosphorus atoms produces the species, NiP(P)4, with the structural and electronic features drastically different from the original NiP. This implies that NiP(P)4 can possess interesting and unusual novel properties, including aromaticity and reactivity, leading to its various beneficial potential applications. Furthermore, NiP(P)4 high stability both in the gas phase and different solvents was shown, implying the feasibility of its synthesis.

Molecular and Electronic Structure of Some Symmetrically meso-Substituted Hg(II)-Porphyrin Complexes

“…Substituted metalloporphyrin complexes structure however is dependent on the central ion and their substituent group. It had been showed that substituted Ni(II)-porphyrin complexes exhibit a negatively curved structure (hyperbolic) with nearly perfect D2d symmetry with the amount of curvature that varies according to the substituent group [8]. Hg(II)-porphyrin complexes however exhibit a structure with positive curvature (elliptic) with nearly perfect C4v symmetry.…”

“…On the other side, porphyrin and its derivatives were also known for their unique photoreactivity [1,2] and narrow band gap for semiconductor applications. Some of porphyrin derivatives in the form of metalloporphyrin complexes has been proven to have the properties of a semiconductor materials such as Pt(II)-porphyrin, Fe(II)-porphyrin, Mg(II)-porphyrin and zinc group-porphyrin complexes [3][4][5][6][7][8].…”

“…On the other side, porphyrin and its derivatives were also known for their unique photoreactivity [1,2] and narrow band gap for semiconductor applications. Some of porphyrin derivatives in the form of metalloporphyrin complexes has been proven to have the properties of a semiconductor materials such as Pt(II)-porphyrin, Fe(II)-porphyrin, Mg(II)-porphyrin and zinc group-porphyrin complexes [3][4][5][6][7][8].Metalloporphyrin complexes performance as semiconducting materials is determined by the central ion of the complexes and the functional group that is substituted on the porphyrin ring [5,9]. We have previously discussed how those factors help us to design a better metalloporphyrin semiconductor by looking into the electronic structures of some meso-substituted M(II)-porphyrin (M = Pt, Cd, Hg) [9].…”

Distortions and Deformations of Metaled Meso-Substituted and Unsubstituted Porphyrins and Derivatives in Crystal Structures

“…These factors influence the electronic density distribution within the core of the macrocycle and thus determine its reactivity and stability, as well [6]- [8].…”

Design a better metalloporphyrin semiconductor: A theoretical studies on the effect of substituents and central ions

“…1 showed the HOMO-LUMO energy gap of metalloporphyrin complexes. The previous study performed by Berbee and Kuznetsov [25] proved that electron donating group will destabilize the orbitals resulting in the decrease of band gap energy and increase of orbitals energy. Table 1 also showed that the band gap energy average increased in the series "HgP-R" -"CdP-R" -"PtP-R".…”