Synthesis and Applications of Monobenzoporphyrins

Abstract

Porphyrins are one of the most abundant macrocyle found in nature [1] which is playing a vital role in biological and material applications [2]. The push-pull porphyrins are used in dye-sensitized solar cells (DSSCs), nonlinear optics (NLO), ion-sensing and catalysis etc [3]. In this regard, MTPP(Benzo)CHO (M = Cu, Zn, Ni and Co) were prepared from the dibromo β-formyl porphyrin using Heck coupling followed by electrocyclization [4] for NLO applications. Further, cyanoacetic acid appended antipodal Zn(II) benzoporphyrin (Figure 1) was synthesized from β-formyl monobenzoporphyrin using Knoevenagel condensation reaction in order to utilize for DSSC application. The UV-Visible absorption spectra of the ZnTPP(Benzo)CHCCNCOOH and the MTPP(Benzo)CHO (M = Cu, Zn, Ni and Co) and MTPPBr2CHO (M = Cu, Zn, Ni and Co) were compared, which show a red-shifted Soret and Q bands as compared to precursor porphyrins. Also, we have studied the electrochemical redox properties of both ZnTPP(Benzo)CHO and ZnTPP(Benzo)CHCCNCOOH. These porphyrins exhibited a cathodic shift in the first redox potentials as compared to ZnTPPBr2CHO. Similarly, CuTPP(Benzo)CHO exhibited a positive shift in the first oxidation potential and a negative shift in the first reduction potential as compared to CuTPPBr2CHO (Figure 1). In this presentation, we will describe the synthesis, spectral and redox properties of monobezoporphyrin derivatives and their application in DSSC. Figure 1: Molecular structures of synthesized porphyrins and their comparative Cyclic voltammograms in CH2Cl2 using TBAPF6 as supporting electrolyte at 298 K.