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Keywords:

charge transfer, corroles, luminescence, pyrimidines, uv/vis spectroscopy, free-base corroles, liquid-membrane electrodes, core-modified corroles, reductive demetalation, copper corroles, mesosubstituted corroles, luminescence properties, cycloaddition reactions, cobalt(iii) corroles, efficient synthesis, Science & Technology, Physical Sciences, Chemistry, Multidisciplinary, Chemistry, UV/Vis spectroscopy, FREE-BASE CORROLES, LIQUID-MEMBRANE ELECTRODES, CORE-MODIFIED CORROLES, REDUCTIVE DEMETALATION, COPPER CORROLES, MESOSUBSTITUTED CORROLES, LUMINESCENCE PROPERTIES, CYCLOADDITION REACTIONS, COBALT(III) CORROLES, EFFICIENT SYNTHESIS, Catalysis, Cross-Linking Reagents, Luminescence, Metals, Molecular Structure, Photolysis, Porphyrins, Pyrimidines, Quantum Theory, Solutions, Spectrophotometry, Ultraviolet, 03 Chemical Sciences, General Chemistry, 34 Chemical sciences

Abstract:

meso-Pyrimidinyl-substituted AB(2)-corroles were efficiently synthesized starting from 5-mesityldipyrromethane and various 2-substituted 4,6-dichloropyrimidine-5-carbaldehydes. The corrole yield was significantly enhanced by optimization of the amount of Lewis acid catalyst (BF3 center dot OEt2). The main advantage of pyrimidinylcorroles over other meso-triarylcorroles is their wide range of functionalization possibilities, which has been explored by nucleophilic and electrophilic aromatic substitution, and Pd-catalyzed cross-coupling reactions. Stepwise substitution of the chlorine functions afforded asymmetrically substituted pyrimidinylcorroles. Due to the lability of the free-base corrole macrocycles, functionalization of the corrole periphery was preferentially performed on the Cu-metalated counterparts. Functionalized free-base AB(2)-pyrimidinylcorroles were, however, readily accessible by the reversible sequence Cu insertion and subsequent reductive demetalation. AB(2)-pyrimidinylcorroles can hence be regarded as highly versatile platforms towards more sophisticated corrole systems. X-ray analysis of a bis(4-tert-butylphenoxy)-substituted Cu-pyrimidinylcorrole showed the typical features of a Cu corrole: short N-Cu distances and a saddled corrole plane. The absorption spectra and photophysical properties of some representative free-base AB(2)-pyrimidinylcorroles were examined in depth. The absorption spectra displayed typical corrole features: intense spin-allowed pi-pi* bands, which can be classified as Soret- and Q-type bands. The photophysical properties, investigated both in fluid solution at room temperature and in rigid matrix at 77 K. were governed by the lowest-lying pi-pi* singlet state: however, in most cases, a state with partial charge-transfer character (from the corrole ring to the pyrimidinyli group) was proposed to contribute to the dynamic Properties of the emissive level.