Case Study for Artificial Photosynthesis: Noncovalent Interactions between C₆₀-Dipyridyl and Zinc Porphyrin Dimer

Abstract

In this study, a new modified C60 derivative with an oPE/oPPV conjugated bridge bearing two pyridyl groups has been used in combination with a flexible porphyrin dimer (ZnP 2 ) to construct an electron donor/acceptor hybrid (C 60 -dipyr·ZnP 2 ). This hybrid is based on metal to ligand coordination between the zinc centers of the porphyrin dimer and the two pyridyl groups that oPE/oPPV linker bears. In order to investigate the interactions between the electron donor and acceptor entities, both in the ground state and in the excited states, comprehensive photophysical assays have been carried out. In particular, both absorption and fluorescence titrations provided evidence for strong interactions between the electron donor and the electron acceptor within the hybrid. A binding constant (K ass) in the order of 5.0 × 105 M–1 has been derived. Furthermore, transient absorption measurements revealed intramolecular electron-transfer from the photoexcited porphyrin dimer (ZnP 2 ) to the fullerene derivative (C 60 -dipyr), leading to a long-lived charge-separated state with a lifetime of up to 1525 ps.

Efficient light harvesting using simple porphyrin-oxide perovskite system

“…Porphyrin as photo-sensitizers was particularly of interest owing to its role in light harvesting in photosynthesis process 25 . In recent years, research into porphyrin dyes, in particular the push–pull type dipolar Zn(II) porphyrins, for DSSCs have tremendously increased because of its intense absorption in wavelength region of 400–480 nm (Soret band, extinction coefficient ε > 110,000 /M-cm ) and 500–700 nm (Q-band, ε > 20,000/M cm), the appropriate LUMO and HOMO energy levels 25 – 27 with versatile structures such as YD-2 porphyrin reported by Gratzel et al 26 , 27 with PCE as high as 11% and PCE as high as 13% 28 with TiO 2 transport layer wherein its application is not limited to substitute ruthenium dyes but in many other visible range applications also. There are several studies which emphasises the challenges in harvesting the sunlight for the entire spectral region for efficient injection of photoexcited electrons into photoanodes using only a single porphyrin dye sensitizer and thus, co-sensitized methods have also been reported in 2011, with PCE of 12.3% for DSSCs 29 .…”

Can MP(P)4 Compounds Form Complexes with C60?

“…We performed the geometry optimizations and frequencies calculations using the Handy and coworkers' long range corrected version of B3LYP, CAM-B3LYP [42] with the split-valence 6-31G* basis set [43,44], further referred to as CAM-B3LYP/6-31G*. So far, different theoretical approaches have been used to study the complexes between porphyrins and their derivatives and fullerenes, for example: pure generalized gradient approximation (GGA) functional PBE, global hybrid meta-GGA functional M06, hybrid functional B3LYP, and wB97XD hybrid density functional including empirical atomic-pairwise dispersion corrections following the Grimme's D2 dispersion scheme (D) by Baruah and co-workers in the studies of systems based on fullerene/graphene oxide and porphyrin/smaragdyrin [33]; hybrid functional B3LYP in the recent study of noncovalent interactions between C 60 -dipyridyl and zinc porphyrin dimer by Stangel et al [45]; B97-D3 functional including dispersion corrections in the study of supramolecular ensembles of conjugated porphyrin dimers with C 60 by Moreira et al [32]; PBE with included semi-empirical 'DFT+D3' term in the studies of fullerene-porphyrin supramolecular nanocables by Buldum and Reneker [31]; CAM-B3LYP along with wB97XD, TPSSh, M06, and M06L functionals in the studies of Rhoda et al on noncovalent complexes of subphthalocyanine derivatives with C 60 and C 70 fullerenes [46]. We decided to choose the CAM-B3LYP approach because of its superiority over the standard "pure" and "hybrid" exchange-correlation functionals in treating noncovalent weak long-distance interactions which should take place in the studied complexes.…”

Controllable Charge-Transfer Mechanism at Push–Pull Porphyrin/Nanocarbon Interfaces

“…15 For these reasons, there has been significant interest in studying molecular-scale carbon-based hybrid materials that could be used in optoelectronic applications. [16][17][18][19][20][21] On the other hand, porphyrin molecules possess excellent light-harvesting features owing to the high absorption cross section of their Soret and Q-bands in the UV/Vis spectral region. 22 Furthermore, this class of molecules exhibits unique photophysical and electrochemical properties, which are tunable by changing the functional groups on the porphyrin core as well as through interactions with metal ions in the core of the porphyrin macrocycle, 2,23 making them valuable molecules for exploring the potential of carbon-based hybrid materials.…”