Synthesis, Structural, Spectral and Electrochemical Redox Properties of N-Fused Porphyrins and Their Photoinduced Electron Transfer Studies with C60 Derivatives
Authors: Sankar Muniappan , Rathi Pinki , Seetharaman Sairaman , D'Souza Francis 
Published: February 2020

Porphyrins exhibit the variation in physicochemical properties according to the substitution at β/meso-positions of the macrocyclic ring which makes them a suitable candidate for various applications [1]. Non-covalent interactions play a significant role in execution of various building blocks which can be used for the inception and implementation of advanced functional materials including various porphyrin-fullerene donor-acceptor dyads [2]. Herein, we have synthesized a new series of β-substituted N-fused porphyrins (MTPP(N-fusedPh)X2, X = H, Br, Ph and PE, M = 2H, Co(II), Ni(II), Cu(II), and Zn(II)) (Figure 1) as donors in order to coordinate with C60 derivatives to form supramolecular dyads. Notably, these porphyrins exhibit very low oxidation potential due to intramolecular charge-transfer from β-arylamine group to porphyrin core. Efficient fluorescent quenching was observed for Zn(II) fused porphyrins while titrating with C60 derivatives due to axial coordination of C60Im to Zn(II) porphyrins. The quenching constants were found in the range of 104-105 M-1 which revealed the stable donor-acceptor dyads formation. The first oxidation potential of supramolecular dyads are anodically shifted (~100 mV) as compared to ZnTPP(N-fusedPh)X2. Photoinduced electron transfer (PET) studies of dyad containing Zn(II) N-fused porphyrin-imidazole appended C60 have been carried out. In this presentation, we will describe about the synthesis, structural, spectral and electrochemical redox properties of N-fused porphyrins and their photoinduced electron transfer studies with various C60 derivatives.

Figure 1. (a) Structure of ZnTPP(N-fusedPh)X2 coordinated with C60Im (b) Fluorescence titration of ZnTPP(N-fusedPh)PE2 (4d) with C60Im (c) Cyclic voltammograms of ZnTPP(N-fusedPh)PE2 (4d) in presence and absence of C60Im.

REFERENCES

(a) Tanaka, T.; Osuka, A. Chem. Soc. Rev.,
2015, 44, 943. (b) Wang, L.; Long, S.; Meng, Li, X.; Zhao, W.; Song, Y.; Cifuentes, M. P.; Humphrey, M. G.; Zhang, C. Org. Biomol. Chem.
2013,
11, 4250. (c) Kumar. R.; Sankar, M. Inorg. Chem. 2014, 53, 12706. (d) Grover, N.; Sankar, M.; Song, Y.; Kadish, K. M. Inorg. Chem. 2016, 55, 584. (e) Chaudhri, N.; Grover, N.; Sankar, M. Inorg. Chem. 2017, 56, 424. (f) Ke, X.; Yadav, P.; Cong, L.; Kumar, R.; Sankar, M; Kadish, K. M. Inorg. Chem. 2017, 56, 8527. (g) Chaudhri, N.; Grover, N.; Sankar, M. Inorg. Chem. 2017, 56, 11532. (h) Ke, X.; Kumar, R.; Sankar, M; Kadish, K. M. Inorg. Chem. 2018, 57, 1490. (i) Chaudhri, N.; Grover, N.; Sankar, M. Inorg. Chem. 2018, 57, 6658. (j) Chaudhri, N.; Grover, N.; Sankar, M. Inorg. Chem. 2018, 57, 11349. (k) Chaudhri, N.; Cong, L.; Grover, N.; Shan, W.; Anshul, K.; Sankar, M.; Kadish, K. M. Inorg. Chem. 2018, 57, 13213. (l) Grover, N.; Chaudhri, N.; Sankar, M. Inorg. Chem. 2019 (in press).

(a) Fukuzumi S. Functional Organic Materials, Wiley-VCH: Weinheim,
2007
, (b) Follana-Berna, J.; Seetharaman, S.; Martın-Gomis, L.; Charalambidis, G.; Trapali, A.; Karr, P. A.; Coutsolelos, A. G.; Fernandez-Lazaro, F.; D’Souza, F.; Sastre-Santos, A. Phys. Chem. Chem. Phys.,
2018, 20, 7798.

Figure 1