Spectral-luminescent properties of meso-tetraarylporphyrins revisited : The role of aryl type, substitution pattern and macrocycle core protonation

Summary, in English

Both the ground (S₀) and the lowest singlet excited states (S₁) for a series of 5,10,15,20-tetraarylporphyrins consisting of two symmetrically and four asymmetrically substituted derivatives (A₄, AB₃, trans-A₂B₂, cis-A₂B₂, A₃B and B₄, where A=phenyl and B=mesityl) are studied by absorption and fluorescence spectroscopies. The rotational degree of freedom of the aryl rings is found to play a crucial role in the discrimination between the radiative and radiationless decays of the S₁ states. This feature is dramatically enhanced upon going from the free base molecules to their mono and diprotonated forms because of the nonplanar macrocycle conformation of the latters. The progressive A to B replacement of the aryl substituents leads to additive spectral changes over the whole series in the free base form. For both mono- and diprotonated species such a gradual additive pattern is broken by a “spectral jump” from the trans to the cis derivative, which is proposed to be a signature of the transition between two macrocycle conformations with different flexibility.

• Author: Irina V. Vershilovskaya; Stefano Stefani; Pieter Verstappen; Thien H. Ngo; Ivan G. Scheblykin; Wim Dehaen; Wouter Maes; Mikalai M. Kruk
• Department/s: Chemical Physics
• Publishing year: 2017
• Language: English
• Pages: 257-267
• Publication/Series: Macroheterocycles
• Volume: 10
• Issue: 3
• Links: http://dx.doi.org/10.6060/mhc160962n
• Document type: Journal article
• Publisher: Ivanovo State University of Chemistry and Technology
• Topic: Analytical Chemistry
• Keywords: Fluorescence; Macrocycle conformation; Meso-substitution; Porphyrin; Protonation
• Status: Published
• ISBN/ISSN/Other: ISSN: 1998-9539