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Introduction

Small molecules bearing functional groups that induce the formation of crosslinked networks can provide a fixed, and long-term thermally stable, morphology for OPV to ensure high performance.¹ In our previous work, we used azido groups to trigger cycloadditions [under a mild thermal annealing temperature (ca. 80 °C)] between an azido-containing additive and a fullerene to fix the morphology of the fullerene units as well as that of the blend film.²

Within the framework of preparing a novel bisazide low bandgap molecule, two failed synthetic experiments were  noticed. The failed synthetic experiments to prepare a stannylated cycopentdithiophene (CPDT) bearing a Bromine or azide functional group will be presented in this paper. The synthesis of CPDT with alkyl bromide and alkyl azide functionality were described in our paper.² In fact, the stannylation of CPDT with alkyl chain was optimised previously in our team.

Protocol

Several attempts were tried to synthesize the stannylated CPDT bearing a bromine or azide without any success. (Scheme1) 

Scheme 1. Attempted synthetic routes toward the synthesis of stannylated CPDT-Br and CPDT-N₃.

Therefore, several parameters were changed during the reaction either by changing the concentration of solution, reaction time, temperature (-15°C to -75°C) and the equivalence of Buli /trimethyltinchloride.