Tuning Optical and Electron Donor Properties by Peripheral Thio–Aryl Substitution of Subphthalocyanine: A New Series of Donor–Acceptor Hybrids for Photoinduced Charge Separation

Abstract

Subphthalocyanine (SubPc), a unique ring-reduced member of the common phthalocyanines family, although known for its higher absorptivity, reveals narrow absorption with peak maxima around 570 nm thus limiting its utility in light-energy-harvesting applications. In the present study, by peripheral thio-aryl substitution of SubPc macrocycle, the spectral properties have been modulated to extend the absorption and emission well into the visible/near-IR region. Additionally, for α-ring-substituted derivatives, facile oxidation of SubPc was witnessed, thus making these derivatives better electron donors. Next, the preparation of donor-acceptor dyads containing the well-known electron acceptor C60 connected to the central boron atom of SubPc was accomplished by making use of the 1,3-dipolar cycloaddition reaction. Control experiments and free-energy calculations using the redox and spectral data suggested that the observed fluorescence quenching of SubPc in these dyads is due to electron transfer. Accordingly, transient spectral studies performed both in polar and nonpolar solvents conclusively proved electron transfer to be the quenching mechanism in these dyads. The measured rate constants by fitting kinetic data revealed efficient charge separation and charge recombination processes, suggesting that these dyads could be useful materials for the construction of light-to-electricity or light-to-fuel production devices.

1,7-Dipyrene-Containing Aza-BODIPYs: Are Pyrene Groups Effective as Ligands To Promote and Direct Complex Formation with Common Nanocarbon Materials?

“…There is no evidence for charge transfer. We note that transient absorption features in the near-IR region reported here are very similar to those in other reports that have interpreted the signals as an indicator of energy and charge transfer in analogous systems. ,,,, Our results demonstrate the potential for dominance of the near-IR transient absorption by direct excitation of independent C 60 in these types of titration studies. This indicates that even at low C 60 concentrations and longer wavelengths in the tail of the C 60 absorption, signals originating from direct fullerene absorption must still be carefully accounted for prior to drawing any conclusions associated with energy or charge transfer.…”

“…Facile formation of stable, long-lived, and charge-separated states is an important initial step in the preparation of efficient organic solar cells. − There are many examples of covalently bound donor–acceptor (D–A) systems, where strong binding provides stability and some degree of design control over the electronic coupling. − When substituted with electron-donating groups capable of intramolecular electron transfer, porphyrins, − phthalocyanines, − subphthalocyanines, − boron-dipyrromethenes (BODIPYs), − and boron-azadipyrromethenes (aza-BODIPYs) − have been demonstrated to be effective and stable assemblies for initial light absorption and charge separation. Organic amines − and ferrocene, − as examples, have been show...…”

Density Functional Theory Investigation on Boron Subphthalocyanine–Ferrocene Dyads

“…Fixing instead each linker and exploring the dependence of moving the linker-donor group from axial to β to α position result in the absorption spectra presented in Figures S19, S20, S21, and S22 in Supporting Information. There is a clear tendency for the Q-band for each linker that a red shift of the maximum absorption is seen when going from axial position to β position to α position, a trend seen for other peripherally substituted SubPcs. , This shows, in line with previous experiments, the greater susceptibility of structures substituted at the α-position to induce changes in the optical properties.…”

The influence of driving force on intramolecular electron transfer: A theoretical study of subphthalocyanine‐AzaBODIPY‐C60 supramolecular triad

“…Currently, a series of D‐A photovoltaic materials have been synthesized based on subPC, ADP, and C 60 . For example, thieno‐pyrrole‐fused BODIPY‐C 60 dyads, phenothiazine‐ADP‐C 60 , and D‐A‐D molecules such as (subPC) 2 ‐ADP and bisferrocene‐ADP, have been synthesized by researchers recently. It is worth noting that in phenothiazine‐ADP‐C 60 triad, ADP unit acts as a donor.…”