The lowest excited triplet (T-1) state of tri-tert-butylpyridinotribenzotetraazaporphinatozinc (ZnPcPy) has been investigated using transient absorption and phosphorescence measurements. The excited-state absorption spectrum of the self-assembled dimer ((ZnPcPy)2) exhibits two sharp absorption bands (658 and 694 nm) in the Q band region, in addition to triplet-triplet absorption at 500 nm. This is the first observation of the Q band of the T-1 phthalocyanine dimer. (c) 2007 Elsevier B.V. All rights reserved.