Photochemical Charge Separation in Closely Positioned Donor–Boron Dipyrrin–Fullerene Triads

Abstract

A series of molecular triads, composed of closely positioned boron dipyrrin-fullerene units, covalently linked to either an electron donor (donor(1)-acceptor(1)-acceptor(2)-type triads) or an energy donor (antenna-donor(1)-acceptor(1)-type triads) was synthesized and photoinduced energy/electron transfer leading to stabilization of the charge-separated state was demonstrated by using femtosecond and nanosecond transient spectroscopic techniques. The structures of the newly synthesized triads were visualized by DFT calculations, whereas the energies of the excited states were determined from spectral and electrochemical studies. In the case of the antenna-donor(1)-acceptor(1)-type triads, excitation of the antenna moiety results in efficient energy transfer to the boron dipyrrin entity. The singlet-excited boron dipyrrin thus generated, undergoes subsequent energy and electron transfer to fullerene to produce a boron dipyrrin radical cation and a fullerene radical anion as charge-separated species. Stabilization of the charge-separated state in these molecular triads was observed to some extent.

Ultrafast Photoinduced Charge Separation in Wide‐Band‐Capturing Self‐Assembled Supramolecular Bis(donor styryl)BODIPY–Fullerene Conjugates

“…Figure4a shows the DPV curves for compounds 1-4 in benzonitrile, 0.1 m (nBu 4 N)ClO 4 .M ultiple oxidation processes were observed. The redox potentials of 1 were very similar to pristine BODIPY [29] while having two styryl groups in compound 2 affected both oxidation andreduction potentials. That is, lower oxidationa nd reduction potentials affecting the overall HOMO-LUMO gap was noticed.…”

Photosynthetic Antenna–Reaction Center Mimicry by Using Boron Dipyrromethene Sensitizers

“…As seen from the reported series of 28-31, the substituted units (pyrene, anthracene, fluorine, and naphthalene) acted as antenna units, BODIPY acted as an electron donor, and C 60 acted as an electron acceptor ( Figure 24). [127] In each compound of this series, efficient energy transfer occurred from the aromatic antenna unit to the BODIPY, for which emission from the BODIPY core was only observed. This process was followed by electron transfer from the singlet BODIPY to the C 60 subunit to yield the charge-separated states with lifetimes of 770, 900, 390, and 770 ps for 28, 29, 30, and 31, respectively.…”

Vectorial Charge Separation and Selective Triplet-State Formation during Charge Recombination in a Pyrrolyl-Bridged BODIPY–Fullerene Dyad

“…In combining BDP and ADP to fullerene, one of the elegant approach developed in our laboratory involve utilization of the central boron, viz., replacing fluorines with a catechol group to which fullerene is attached, BDP-C60 (see compound 2 in Figure 1). [51][52][53][54][55][56] In an effort to rationalize the effect of boron-connected fullerene over peripheral carbon-connected fullerene, in the present study we have synthesized a new dyad using 3-pyrrolyl functionalized BDP, BDPPy-C60 (compound 1 in Figure 1). Systematic spectral and photochemical studies have been performed in benzonitrile and toluene on 1, and compared to the results reported earlier on compound 2.…”