Functionalization of dendrimers with oligothiophenes at the periphery

The peripheral functionalization of conventional dendrimers containing flexible and saturated spacers with oligothiophenes was reported by Miller et al. [498], Bi- and quaterthiophenes were attached to the periphery of the 36-acid terminated G2-dendrimer through esterification with a (2-hydroxyethyl)thio linker (Chart 1.74). The moderate conductivity of l2-doped films of dendrimers 5.52 and 5.53 increased by two orders of magnitude when they were exposed to solvent vapors. 

Reagents and Conditions (i) a. G4-NH2, CH2Cl2/MeOH b. NaBHsCN (ii) Pd(OAc)2 NaBH4 or HAUCI4 SHgO, NH2NH2. 

The same group further prepared dendrimer 5.63 by inserting a bithiophene unit between the core of 5.60 and the periphery (Chart 1.76). Despite its relatively large optical bandgap of 2.1 eV, fabrication of OSCs based on a blend of 5.63 and PCBM (1 4) revealed a power conversion efficiency of 1.3 % under simulated AMI.5 illumination [506]. 

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