Journal of Porphyrins and Phthalocyanines J. Porphyrins Phthalocyanines 2016; 20: 744–751 DOI: 10.1142/S1088424616500656 Published at http://www.worldscinet.com/jpp/ Copyright © 2016 World Scientific Publishing Company INTRODUCTION Porphyrins and their metal derivatives are of considerable importance owing to their applications in various fields such as self-assembly, sensors, non-linear optics, light emitting diodes and dye sensitized solar cells to name a few. Non-covalent interactions like hydrogen bonding, labile metal–ligand bonds, ion–ion, dipole– dipole, ion–dipole and π–π interactions play crucial role in developing various inter-molecular building blocks which can be utilized for the construction of advanced functional materials [1, 2]. One aim of developing such assembled materials is to have artificial systems which can trap and process solar energy convincingly [3]. Both porphyrins and fullerenes are electrochemically active, purple chromophores [4]. Porphyrins have typically high electronic excitation energies generally exceeding 2.0 eV which favor energy releasing electron transfer and thereby pave a way for conversion of light energy into chemical/electrical energy [5]. Good and efficient electron acceptors are hugely desired and in this regard fullerenes are assuring species. The birth of fullerene in the early twentieth century brought to limelight a versatile acceptor [6]. Curved π-surface on fullerene makes it a naturally tailored moiety to be exploited for architecturing supramolecular assemblies. Fullerene has three degenerate LUMOs which are low on energy scale making it a strong electron acceptor in general and for solar stimulated processes in particular [6a, 6b]. Among the earliest known conjugates of fullerene were its cocrystallites with ferrocene, S 8 and SbPh 3 [7]. Porphyrins are easily oxidizable species and give intense spectra in the visible region [8]. Also porphyrins are tetragonal and fullerenes are spherical which makes their spontaneous attraction all the more feasible [8a]. The presence of porphyrin moiety in various biological processes such as photosynthesis led researchers to Synthesis, electrochemical and complexation studies of Zn(II) aryloxyporphyrins with fullerene C 60 Tawseef Ahmad Dar # , Mandeep K. Chahal # , R. Ashwin Kumar and Muniappan Sankar* ◊ Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India Received 14 February 2016 Accepted 17 March 2016 ABSTRACT: A new series of aryloxyporphyrins bearing benzyl and naphthyl substituents viz., ZnTBPP (1), ZnTNPP (2) and ZnONPP (3) has been synthesized and characterized by UV-vis, fluorescence and 1 H NMR spectroscopic techniques and mass spectrometry. 1–3 have been utilized as donors to interact with fullerene (C 60 ) acceptor to form 1:1 complex in toluene at 298 K. The subsequent investigation into quenching measurements with concomitant increase in fullerene concentration revealed effective quenching constants. The calculated association constants were in the order of 10 3 M -1 . However, ZnTNPP (2) exhibited higher binding constant as compared to other analogs due to effective π–π interactions. ZnONPP (3) exhibited 3.4 times lower association constant than ZnTNPP (2) due to steric hindrance offered by meso-(3,5-dinapthyloxyphenyl) groups. The geometric and electronic structure of Zn(II) porphyrin-fullerene dyad was probed by DFT calculations which suggested the possibility of charge transfer from meso-aryloxyporphyrin core to fullerene C 60 . KEYWORDS: meso-aryloxyporphyrins, supramolecular dyad, porphyrin-fullerene host–guest complexes. ◊ SPP full member in good standing *Correspondence to: Muniappan Sankar, email: sankafcy@iitr. ac.in, tel: +91 1332-284753, fax: +91 1332-273560 # The authors contributed equally