Synthesis, Characterization and Dielectric Properties of New 5-(4-Hydroxyphenyl)-10,15,20-tri-4-[2-(3-pentadecylphenoxy)ethoxy]phenyl porphyrin and Their Ni, Co and Cu Complexes

Abstract

New asymmetric cardanol-based porphyrins, free-base and coordinated with Ni, Co and Cu, were synthesized and completely characterized as A3B type. Such porphyrins were obtained aiming improved solubility in polar solvents due insertion of an −OH phenolic group. Their thermal and dielectric properties were also evaluated. Changes in the synthetic route reduced the reaction time and improved the yields of the aldehyde precursor obtainment. Electronic absorption spectra of the new porphyrins in CH 2 Cl 2 , EtOH and acetone, indicated a decrease in the ε (molar absorptivity) values with increasing solvent polarity, except for the nickel complex which, in acetone, showed a slight increase of 2% in the ε value. The dielectric measurements showed that the conductivity (σ) and the loss tangent (tan δ) increased with frequency, but the permittivity (ε') decreased. The results showed that the coordination of the porphyrin promoted a significant change in thermal and dielectric properties, specially for to the Ni-complex compound, which presented the best dielectric properties with interesting values of permittivity and loss tangent at 100 MHz (19.46 and 0.011 a.u., respectively). Keywords: asymmetric porphyrins, cardanol, dielectric properties IntroductionPorphyrins are relatively planar aromatic system consisting of four pyrrole type rings joined by four methynic carbons. They have attracted scientists from many areas due to their biological importance, their fascinating physical, chemical, and spectroscopic properties.1 These compounds have a high electron density due to its 18 π-electrons delocalized on the macrocyclic ring, which are responsible for their spectroscopic characteristics. 2Porphyrin and its derivatives play multiple roles in nature, such as energy transfer and light absorption in a wide range of the electromagnetic spectrum. Such features are of great interest to the industry of optoelectronic components, such as solar cells, due to its ability to act as photosensitizers when irradiated under visible light.3 Thus, this is certainly one of the most promising areas of application for these compounds. The structural modeling and synthesis of new porphyrins has grown exponentially in order to control their electronic and thermal properties. 4 The addition of substituents at the meso positions and metal ions in the center of porphyrins can improve the electrical and magnetic properties, protecting against auto-oxidation and reducing the formation of dimers. However, these structural modifications can promote, in some cases, a significant decrease in their planarity. 5A simple way to obtain porphyrins is the acid catalyzed condensation reaction of pyrrole with specific aldehyde, followed by oxidation of the porphyrinogen. This procedure, originally developed by Rothemund,6 has been refined by [7][8][9] due to the addition of metal salts to the reaction. Despite the modest yields, the relative simplicity of this method has become suited for preparation of large amounts of tetraarylporphyrins. Higher yields an...

Light-Emitting Porphyrin Derivative Obtained from a Subproduct of the Cashew Nut Shell Liquid: A Promising Material for OLED Applications

“…Based on these considerations, and those in previous works from our group regarding the preparation of meso -porphyrins [18,21,23,24,25,26], we report the synthesis of cardanol-derivate porphyrins with respect to its application as an emitting layer in OLEDs. The photophysical and electrochemical properties of the porphyrins are investigated in solution and in thin film, and we also investigate the use of these compounds as emitters in simple OLED devices through electroluminescence analysis.…”

“…CNSL is a renewable and abundant source of phenolic compounds, obtained as a subproduct of the cashew nut industry ( Anacardium occidentale L.) [16,17,18]. The industrial CNSL is mainly composed by cardanol (about 65%), which presents interesting chemical characteristics and allows diverse functionalization and applications [19,20,21,22].…”

Nanomaterials Based on Fe3O4 and Phthalocyanines Derived from Cashew Nut Shell Liquid

“…t -CNSL is considered one of the richest natural sources of phenolic compounds; it is a renewable oil with low commercial value [18,19]. It consists of a mixture of long alkyl chain phenols (cardanol, cardol, anacardic acid and 2-methylcardol), with interesting properties and the possibility of chemical transformation for various applications [20,21,22,23].…”

New ZnO@Cardanol Porphyrin Composite Nanomaterials with Enhanced Photocatalytic Capability under Solar Light Irradiation

“…The H 2 Pp shows axial and angular deformation of the N-H bond of the macrocycle at 3327 cm −1 and 967 cm −1 respectively, two bands between 2919 and 2856 cm −1 attributed to stretching of the C–H bond of the aliphatic side chains derived from cardanol and a band at 1245 cm −1 due to the axial deformation of the C–N bond typical of the pyrrole ring [ 37 ]. For metalloporphyrin CuPp, the main change observed is in the disappearance of N–H vibrations and the appearance of N–Cu absorption band at 995 cm −1 [ 38 ]. Furthermore, in the spectra of ZnO, the observed characteristic peaks corresponding to the absorption bond of Zn–O and Zn–O–Zn in the range of 400–500 cm −1 .…”