Leo Mandić

The photochemical reactivity and photophysical and electrochemical properties of a series of N-adamantylphthalimides bearing carboxylic functional groups were investigated. Upon irradiation (with or without a triplet sensitizer), the compounds undergo decarboxylation via photoinduced electron transfer (PET) from the carboxylate to the phthalimide. UV-vis and fluorescence pH titrations were used to determine pK_a values for the prototropic forms, which were put in connection with the quantum yields of the reaction (Φ_R). The compounds bearing electron donors OH and OCH₃ at the phthalimide 4 position are fluorescent (Φ_F = 0.02–0.49) and PET takes place from both singlet and triplet excited states. The estimated rate constants for PET in the singlet excited states for the methoxy- and amino-substituted phthalimides are (2.0 ± 0.1) × 10⁹ s⁻¹ and (3.4 ± 1.0) × 10⁷ s⁻¹, respectively. Laser flash photolysis (LFP) was conducted to characterize the triplet excited states, which are populated less efficiently for compounds with electron donors. The PET is reversible and the overall Φ_R depends on the rates for back electron transfer, protonation of the phthalimide radical anion and decarboxylation. The plausible photochemical and photophysical pathways depend on the phthalimide substituents, which is important for the use of phthalimide derivatives in organic synthesis and photocatalysis.

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

In this study, three groups of adamantylphthalimides, bearing different substituents at the phthalimide moiety, N‐(4′‐R²)phthalimidoadamantanes (1–7), 3‐[N‐(4′‐R²)phthalimido]‐1‐adamantanols (8–10), and 3‐[N‐(4′‐R²)phthalimido]adamantane‐1‐carboxylic acids (11–15), were synthesized and screened against tumor cells and viruses. The most potent compounds are not substituted at the adamantane and bear an OH or NH₂ substituent at the phthalimide (compounds 3 and 5). The antiproliferative activities of compounds 3 and 5 are in the micromolar range, much higher than the one of thalidomide. A minor antiviral activity against cytomegalovirus and varicella‐zoster virus was found for compounds 3 and 5, but these compounds lacked selectivity. The results presented are important for the rational design of the next‐generation compounds with anticancer and antiviral activities.