title: Synthetic, structural, and photophysical exploration of meso-pyrimidinyl-substituted AB2-corroles.
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 (BF(3).OEt(2)). 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 pyrimidinyl group) was proposed to contribute to the dynamic properties of the emissive level.
authors.affiliation: Molecular Design and Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
authors.forename: Thien H
authors.initials: TH
authors.lastname: Ngo
authors.forename: Fausto
authors.initials: F
authors.lastname: Puntoriero
authors.forename: Francesco
authors.initials: F
authors.lastname: Nastasi
authors.forename: Koen
authors.initials: K
authors.lastname: Robeyns
authors.forename: Luc
authors.initials: L
authors.lastname: Van Meervelt
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Campagna
authors.forename: Wim
authors.initials: W
authors.lastname: Dehaen
authors.forename: Wouter
authors.initials: W
authors.lastname: Maes
mesh_terms: D002384:Catalysis; D003432:Cross-Linking Reagents; D049449:Luminescence; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure; D010782:Photolysis; D011166:Porphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D011743:Pyrimidines / Q000138:chemical synthesis* / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003432:Cross-Linking Reagents; D008670:Metals; D011166:Porphyrins; D011743:Pyrimidines; D012996:Solutions; C431863:corrole