A Theoretical Study of Ligand Effects on the Electronic Structures of Ligated Zinc Porphyrin using Density Functional Theory

Abstract

We study the ligand eŠect on the LUMO/HOMO of ligated zinc porphyrin (ZnP) by utilizing DFT. The ligated ZnPs are zinc meso-tetraphenylporhyrin (ZnTPP), zinc tetrabenzoporphyrin (ZnTBP), zinc meso-tetraphenyltetrabenzoporphyrin (ZnTPTBP) andˆve-coordination ZnTPP with imidazole (ZnTPP(Im)). The ligands decrease LUMO-HOMO energy gap (DE  ) of ligated ZnPs with respect to non-ligated ZnP, which is in good agreement with experiments. LUMO of ZnTPP and ZnTBP is stabilized by LUMO＋1 (b 1 -type, C 2v -symmetry) of respected ligands, while their HOMO is destabilized by HOMO -4 (a 1 , C 2v ) and HOMO (a 2 , C 2v ) of respected ligands. DE  of ZnTPP and ZnTBP can be adjusted by changing the ligand's electronegativity, such as halogen substitution at the ligands. Halogenated ZnTPP has DE  smaller than ZnTPP, which conrms the experiments. Geometry change in ZnP, which allows the intermolecular perturbation in the frontiers molecular orbitals, shifts LUMO/HOMO energies as it is shown for ZnTPP(Im) and ZnTPTBP. The calculated DE  of ZnTPP(Im) and ZnTPTBP are greater than that of ZnTPP and ZnTBP.

Fluorescence‐Lifetime Imaging and Super‐Resolution Microscopies Shed Light on the Directed‐ and Self‐Assembly of Functional Porphyrins onto Carbon Nanotubes and Flat Surfaces

“…The calculated energy band gap for Zn II ‐porphyrin was 3 eV, which indicates a visible light absorption and promising potential photovoltaic properties that could be applied in the design of solar cells. The energy gap is in accordance with results recently reported for Zn II ‐porphyrin species . Together with the molecular orbital structure and the calculated energy level, it can be found that, after modification at both meso ‐and β‐positions with aryl thioacetate‐functionalised side groups and hexyl chains, respectively, the areas of high electron‐density were moved from the macrocyclic ring (shown in HOMO) to meso ‐ (as shown in LUMO) and β‐positions (as shown in LUMO+1).…”

The transition state conformational effect on the activation energy of ethyl acetate neutral hydrolysis

“…For the exchange-correlation functional, we employ B3LYP [31] and CAM-B3LYP [32] which have been integrated into the software as well. The former has provided good prediction in our previous studies on molecular orbital interaction problems [33], [34], [35], [36], excitation in solvent problems [37], [38], and reaction path coordinate to calculate the tunneling probability [39], [40], [41]. Meanwhile, the latter is needed to consider the correction of the long-range interaction in states 1a , 1b , and 1c .…”

A Density-Functional Study on the Change of Q/B-Band Intensity Ratio of Zinc Tetraphenylporphyrin in Solvents

“…Our previous works 10,27) suggest that HOMO-HOMO¹1 energy difference of ligated ZnPs [ZnTPP, ZnTBP, zinc tetraphenyltetrabenzoporphyrin or ZnTPTBP, and ZnTPP with axial imidazole ligand or ZnTPP(Im)] that are calculated by DFT are wider than non-ligated one. While in non-ligated ZnP these two orbital has 0.04 eV energy difference, in ZnTPP it is 0.19 eV, and it is wider than ZnTBP, ZnTPTBP and ZnP(Im).…”

“…In addition, the frontier orbital ordering is similar to non-ligated ZnP. 10) Therefore we can use the electronic structure of non-ligated ZnP as a comparison for the electronic structure of ZnTPP. And third, ZnTPP is experimentally well studied.…”

“…[11][12][13][14][15][16][17][18] The shifting in energy peak of Q-band due to the ligand effect can be explained from orbital interactions approach between the core part of metalloporphyrin and its ligand part. 10) However, to the best of our knowledge, there is lack of theoretical explanation on the change in visible spectrum of metalloporhyrin in solvents.…”