Solvent mediated intramolecular photoinduced electron transfer in a fluorene-perylene bisimide derivative.

Photoinduced electron transfer from fluorene to perylene bisimide has been studied for 2,7-bis(N-(1-hexylheptyl)-3,4:9,10-perylene-bisimide-N'-yl))-9,9-didodecylfluorene (PFP) in 11 different organic solvents. The intramolecular charge-separated state in PFP is almost isoenergetic with the locally excited state of the perylene bisimide. As a consequence of the small change in free energy for charge separation, the electron transfer rate strongly depends on subtle changes in the medium.

The importance of nanoscopic ordering on the kinetics of photoinduced charge transfer in aggregated pi-conjugated hydrogen-bonded donor-acceptor systems.

Aggregated complexes of diaminotriazine oligo(p-phenylene vinylene) (OPV) units hydrogen bonded to different complementary perylene bisimide (PERY) compounds have been investigated by means of absorption, circular dichroism, photoluminescence, and photoinduced absorption spectroscopy. These studies reveal that in the aggregated state an ultrafast photoinduced charge separation occurs via an intermolecular pathway in the J-type stack of hydrogen-bonded OPV-PERY arrays. The subsequent charge recombination reaction strongly depends on small structural differences within the J-type geometry as revealed by comparison of stacked supramolecular dimers, trimers, and covalently OPV-PERY linked systems.

Influence of intermolecular orientation on the photoinduced charge transfer kinetics in self-assembled aggregates of donor-acceptor arrays.

The kinetics of photoinduced charge transfer reactions in covalently linked donor-acceptor molecules often undergoes dramatic changes when these molecules self-assemble from a molecular dissolved state into a nanoaggregate. Frequently, the origin of these changes is only partially understood. In this paper, we describe the intermolecular spatial organization of three homologous arrays, consisting of a central perylene bisimide (PERY) acceptor moiety and two oligo(p-phenylene vinylene) (OPV) donor units, in nanoaggregates and identify both face-to-face (H-type) and slipped (J-type) stacking of the OPV and PERY chromophores.

Sequential energy and electron transfer in aggregates of tetrakis[oligo(p-phenylene vinylene)] porphyrins and C60 in water.

Chiral aggregation of oligo(p-phenylene vinylene)-functionalized Zn and free-base porphyrins is observed in water. The formation of mixed assemblies containing both porphyrins results in sequential energy transfer from OPV via zinc porphyrin to free-base porphyrin. Furthermore, the incorporation of C60 as electron acceptor yields a charge separated state by ultimate electron transfer.

Supramolecular p-n-heterojunctions by co-self-organization of oligo(p-phenylene vinylene) and perylene bisimide dyes.

Comparative studies on hydrogen-bonded versus covalently linked donor-acceptor-donor dye arrays obtained from oligo(p-phenylene vinylene)s (OPVs) as donor and bay-substituted perylene bisimides (PERYs) as acceptor dyes are presented. Both systems form well-ordered J-type aggregates in methylcyclohexane, but only hydrogen-bonded arrays afford hierarchically assembled chiral OPV-PERY dye superstructures consisting of left-handed helical pi-pi co-aggregates (CD spectroscopy) of the two dyes that further assemble into right-handed nanometer-scale supercoils in the solid state (AFM study). In the case of hydrogen-bonded arrays, the stability of the aggregates in solution increases with increasing conjugation length of the OPV unit.

Supramolecular control over donor-acceptor photoinduced charge separation.

A novel donor-bridge-acceptor system has been synthesized by covalently linking a p-phenylene vinylene oligomer (OPV) and a perylene diimid (PERY) at opposite ends of a m-phenylene ethynylene oligomer (FOLD) of twelve phenyl rings, containing nonpolar (S)-3,7-dimethyl-1-octanoxy side chains. For comparison, model compounds have been prepared in which either the donor or acceptor is absent. In chloroform, the oligomeric bridge is in a random coil conformation.

Singlet-energy transfer in quadruple hydrogen-bonded oligo(p-phenylenevinylene)perylene-diimide dyads.

The photophysical properties of a supramolecular donor-acceptor dyad consisting of an oligo(p-phenylenevinylene) unit and a perylene-diimide unit are described. The dyad is created by functionalising the two chromophores with quadruple hydrogen bonding 2-ureido-4[1H]-pyrimidinone units, which provide a high association constant (K approximately 10(8) M-1 in toluene). This feature enabled us to study the time-resolved photoinduced singlet-energy transfer reaction between the two chromophores in dilute solution with transient pump-probe spectroscopy.

Orientational effect on the photophysical properties of quaterthiophene-C60 dyads.

Two quaterthiophene-[60]fullerene dyads in which C60 is singly (4TsC) or doubly (4TdC) connected to the inner beta-position of the terminal thiophene rings have been synthesized. The electronic properties of these donor-acceptor compounds were analyzed by UV/Vis spectroscopy and cyclic voltammetry, and their photophysical properties in solution and in the solid state by (time-resolved) photoluminescence (PL) and photoinduced absorption (PIA) spectroscopy. Both the flexible and geometrically constrained 4TsC and 4TdC dyads exhibit photoinduced charge transfer from the quaterthiophene to the fullerene in toluene and o-dichlorobenzene (ODCB).

Preferential hetero-dimer formation and equilibrium dynamics of self-complementary bifunctional oligo(p-phenylenevinylene) and C60 ureido-pyrimidinone derivatives in solution.

The formation of hetero-dimers of bifunctional oligo(p-phenylenevinylene) and C60 ureido-pyrimidinone derivatives has been observed by 1H-NMR and fluorescence techniques.