Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

Nine new quadrupolar chromophores based on diketopyrrolopyrrole were designed and prepared by cross-coupling reactions. The property tuning has been achieved by structural variation of the peripheral substituents (donor) and enlargement of the π-system. Fundamental properties of target molecules were studied by differential scanning calorimetry, electrochemistry, and absorption and emission spectra. Nonlinear optical properties were studied by measuring the third harmonic generation. The experimental data were completed by quantum-chemical calculations and structure–property relationships were elucidated.