Sustainable Access to π-Conjugated Molecular Materials via Direct (Hetero)Arylation Reactions in Water and under Air.

Direct (hetero)arylation (DHA) is playing a key role in improving the efficiency and atom economy of C-C cross coupling reactions, so has impacts in pharmaceutical and materials chemistry. Current research focuses on further improving the generality, efficiency and selectivity of the method through careful tuning of the reaction conditions and the catalytic system. Comparatively fewer studies are dedicated to the replacement of the high-boiling-point organic solvents dominating the field and affecting the overall sustainability of the method. We show herein that the use of a 9:1 v/v emulsion of an aqueous Kolliphor 2 wt% solution while having toluene as the reaction medium enables the preparation of relevant examples of thiophene-containing π-conjugated building blocks in high yield and purity.

[1]Benzothieno[3,2-b][1]benzothiophene-Phthalocyanine Derivatives: A Subclass of Solution-Processable Electron-Rich Hole Transport Materials.

The [1]benzothieno[3,2-b][1]benzothiophene (BTBT) planar system was used to functionalize the phthalocyanine ring aiming at synthesizing novel electron-rich π-conjugated macrocycles. The resulting ZnPc-BTBT and ZnPc-(BTBT)4 derivatives are the first two examples of a phthalocyanine subclass having potential use as solution-processable p-type organic semiconductors. In particular, the combination of experimental characterizations and theoretical calculations suggests compatible energy level alignments with mixed halide hybrid perovskite-based devices. Furthermore, ZnPc-(BTBT)4 features a high aggregation tendency, a useful tool to design compact molecular films. When tested as hole transport materials in perovskite solar cells under 100 mA cm-2 standard AM 1.5G solar illumination, ZnPc-(BTBT)4 gave power conversion efficiencies as high as 14.13 %, irrespective of the doping process generally required to achieve high photovoltaic performances. This work is a first step toward a new phthalocyanine core engineerization to obtain robust, yet more efficient and cost-effective materials for organic electronics and optoelectronics.