Hyperporphyrin effect on oxygen sensitivity of free meso-tetraphenylporphyrins

Abstract

A series of dyes; three symmetric free meso-tetraphenylporphyrins, bearing phenylacetylide (H2-TPA), hexyloxy (H2-OHex) or without peripheral substituent (H2-TPP) were chosen as luminophore to explore the effect of meso-substitution on the oxygen sensing ability. These dyes were incorporated into poly(trimethylsilylpropyne) [poly(TMSP)], polymethylmethacrylate (PMMA) and silicone matrices along with additives such as perfluorododecanoic acid (PFC) to improve the oxygen sensitivity as well as ionic liquid to favor the microfiber preparation by electrospinning. The pH of the medium is affected by the composition of the cocktail, a non-trivial effect which induce protonation of the free meso-tetraphenylporphyrin derivatives bearing electron donor (H2-OHex) and withdrawing substituents (H2-TPA), which results in absorbance and emission spectroscopic modifications called elsewhere hyperporphyrin effect. Spectrophotometric titrations were carried out by using HClO4 in THE solution and PFC in [poly(TMSP)]-based thin film to study the hyperporphyrin effect of H2-TPA, H2-OHex and H2-TPP showing the influence of the substituent bn the pKa of the inner nitrogen's. The ratio of PFC/dyes optimization was prospected and the influence of the pH/protonation on the steady-state oxygen sensitivity was studied. (C) 2017 Elsevier Ltd. All rights reserved.