Fullerene acceptors/derivatives

Figure 1.54. A bichromophoric dyad used for photoinduced electron transfer studies and obtained as a mixture of diastereoisomers. It includes a 1,2-dihydro[60]fullerene acceptor, a [Ru(bpy)3]2+ donor unit, and a rigid spacer derived from 4,5-dihydrotestosterone. (The asterisk marks the stereogenic center giving rise to the diastereoisomerism.)...

Consequently, we will centre our attention on the main type of acceptors according to their different molecular nature. Thus, we will focus on derivatives of the parent molecules TCNQ, dicyano-p-quinonediimine (DCNQI), other polycyano derivatives, dithiolene metal complexes (l,3-dithioIe-2-thione-4,5-dithiolate, dmit) and some interesting cases in the emerging chemistry of fullerene [13] derivatives as shown in Figure 1.1. 

Magnetic field effects on the reaction kinetics or yields of photochemical reactions in the condensed phase have been studied [20-23]. They have proved powerful for verifying the mechanism of photochemical reactions including triplet states. Previously, we obtained photogenerated triplet biradicals of donor-acceptor linked compounds, and found that the lifetimes of the biradicals were remarkably extended in the presence of magnetic fields up to 1T [24]. It has been reported that Cgo and its derivatives form optically transparent microscopic clusters in mixed solvents [25,26]. The clustering behavior of fullerene (C o) is mainly associated with the strong three-dimensional hydrophobic interactions between the C o units. Photoinduced... 

Recently, photovoltaic cells that use a narrow band conjugated polymer PDDTT 196 as the electron donor and fullerene derivative 197 as the electron acceptor were developed. These cells show a short circuit density (J c) of 0.83mAcm , an open current voltage (Fqc) of 0.35 V, a fill factor (FF) of 38.6% under AM.5 simulator (lOOmWcm ) and unprecedented photocurrent response wavelengths up to llOOnm <2006APY081106>. 

As mentioned previously, photocycloaddition reactions are a useful method for obtaining fullerene derivatives fused directly to heterocycles. Such compounds have attracted much interest because they might have interesting properties, e.g., amino acid fullerene derivatives as biologically active compounds or pyrrolidino-fullerenes as key precursors for a great number of fullerenes donor-acceptor bridged dyads and triads. Fullerenes functionalized with silicon compounds are of great interest in materials science. The synthesis of these compounds will be described in this section. 

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