Amorim, Ana C.Morgado, JorgeRamalho, João P. PratesCruz, HugoCunha, CarlaPaixão, José A.Melo, J. Sérgio Seixas deLopes, Susana M. M.Branco, Luís C.Burke, Anthony J.2026-01-302026-01-302025-12-212633-5409PURE: 151570683PURE UUID: 82583431-add0-46b2-9592-c149d32522f7Scopus: 105024549662WOS: 001606138400001http://hdl.handle.net/10362/199879Publisher Copyright: This journal is © The Royal Society of ChemistryDespite its promising electronic and semiconducting properties, 12H-phthaloperin-12-one remains a largely unexplored molecule, with limited studies regarding the impact of structural modifications on its properties and its application in light-emitting devices. To address this gap, we report the synthesis of 12 novel phthaloperinone derivatives, designed to fine-tune the photophysical, electrochemical, thermal and electroluminescence properties through the incorporation of electron-donating and electron-withdrawing substituents. The majority of substituents was found to interfere with the electronic distribution in the phthaloperinone core during the electronic excitation process. The introduction of a triphenylamine unit, as in compounds 3f/4f, resulted in the lowest energy gap of 2.22 eV, making this isomeric mixture a promising candidate for use as an organic semiconductor material. Electrochemical studies demonstrated that compounds 3e/4e–3h/4h and 3l/4l exhibited enhanced electrochemical stability, while thermal analysis showed that the pyrene-substituted derivative (3e/4e) displayed the highest thermal resistance (Td= 458 °C). Organic light-emitting diodes were fabricated to evaluate their electroluminescence properties. Compounds 3l/4l, which contain a phenyltriazolyl unit, achieved the best performance, displaying a maximum luminance of 99 cd m−2at 7.5 V, a luminous efficiency of 0.014 cd A−1, and a turn-on voltage of 3.3 V. These findings provide valuable insights into the structure–property relationships of phthaloperinone derivatives and highlight their potential for a wide range of applications, including electronic and optoelectronic devices.124363536engChemistry (miscellaneous)General Materials Sciencejournal article10.1039/d5ma00761ehttps://www.scopus.com/pages/publications/105024549662https://www.webofscience.com/wos/woscc/full-record/WOS:001606138400001