Novel, soluble diphenyl-diketo-pyrrolopyrroles: Experimental and theoretical study

• Published in: Dyes and pigments Vol. 84; no. 2; pp. 176 - 182
• Main Authors: Vala, M., Vyňuchal, J., Toman, P., Weiter, M., Luňák, S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2010
• Subjects: Absorption; Diketo-pyrrolo-pyrrole; DPP; Fluorescence; Photoluminescence; Fluorescence; Absorption; Diketo-pyrrolo-pyrrole; DPP; Photoluminescence
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2009.07.014

Derivatives of diphenyl-diketo-pyrrolopyrrole, possessing electron-donating or withdrawing groups in the p-position of the phenyl, were synthesized and studied using optical characterization (absorption, fluorescence, time-resolved fluorescence) and quantum chemical calculation. An increase in absorption coefficient ≥10 5 dm 3 mol −1 cm −1 was observed using electron–donor groups; a bathochromic shift in both absorption and luminescence peaks was observed as a result of increased conjugation. Soluble derivatives were obtained by the introduction of alkyl groups (by N-alkylation) in the central pyrrolopyrrole unit. Calculated phenyl torsion angles using HF and B3LYP methods showed that the loss of molecule planarity reduced the extent of overlap between the π-orbitals of the central pyrrolopyrrole unit and phenyls after N-alkylation. This treatment thus reduced both the bathochromic shift and increased absorption coefficient. The presence of the donor or acceptor groups in itself does not influence molecule planarity.