Homoleptic complexes of a porphyrinatozinc(II)-2,2′:6′,2"-terpyridine ligand

Three homoleptic complexes containing the metalloligand 7-(4-([2,2': 6', 2 ''-terpyridin]-4'-yl) phenyl)5,10,15,20- tetraphenylporphyrinatozinc(II), 1, have been prepared. [Zn(1)(2)][PF6](2), [Fe(1)(2)][P-6](2) and [Ru(1)(2)][PF6](2) were characterized by H-1 and C-13 NMR spectroscopy and mass spectrometry, and the electrochemical and photophysical properties of the complexes have been investigated. In solution, each complex undergoes two reversible porphyrin-centred oxidation processes, with an additional reversible metal-centred oxidation for [Fe(1)(2)][PF6](2) and [Ru(1)(2)][PF6](2). Solution absorption spectra are dominated by the Soret and Q bands of the metalloligand 1. Spectroelectrochemical data for the complexes are presented. The results of a nanosecond transient absorption spectroscopic investigation of [Zn(1)(2)][PF6](2), [Fe(1)(2)][PF6](2) and [Ru(1)(2)][PF6](2) are presented. For [Zn(1)(2)][PF6](2), S-1 excitation leads to an efficient intersystem- crossing to the T-1 state, whilst for [Fe(1)(2)][PF6](2), excitation of the (MLCT)-M-1 transition is followed by fast deactivation to the (MC)-M-3 state followed by thermal decay to the ground state. Excitation of the 1MLCT transition of [Ru(1)(2)][PF6](2) results in an intersystem crossing to (MLCT)-M-3; triplet-to-triplet energy transfer occurs giving the [Zn(TPP)] T-1 state which regenerates the ground state of the complex.