The binding properties between meso-tetrakis(4-(N-methylpyridiumyl))porphyrin (TMPyP4) and the parallel DNA G-quadruplex (G4) of telomeric repeated sequence 5ƍ-TTAGGG-3ƍ have been characterized by means of circular dichroism, steady-state absorption, steady-state fluorescence and picosecond time-resolved fluorescence spectroscopies. The binding constant and the saturated binding number were determined as 1.29×10 6 (mol/L) 1 and 3, respectively, according to steady-state absorption spectroscopy. Based on the findings by the use of time-resolved fluorescence spectroscopic technique, it is deduced that TMPyP4 binds to a DNA G-quadruplex with both the thread-intercalating and end-stacking modes and at the saturated binding state, one TMPyP4 molecule intercalates into the intervals of G-tetrads while the other two stack to the ends of the DNA G-quadruplex.

Photoinduced electron transfer (ET) between C 60 and porphyrin (P) in a new polymer containing porphyrin, poly(p-phenylenevinylene), and pendant fullerene units has been investigated by nanosecond transient absorption and phosphorescence spectroscopy. Compared to the physically doping material systems, binding porphyrin/C 60 through chemical bonds in a polymer detains the formation of the triplet states of porphyrins and C 60 . The formation of intermediate charge transfer state (CSS) of P ·+ -C 60 · was observed, which led to the delayed formation of triplet states of porphyrins and C 60 . The reduced opto-electronic properties, such as optical limiting performance, were also observed, which resulted from the delayed formation of triplet states. The results presented in this article are significant in understanding the complicated spectral characteristics of the triplet state and charge transfer of the porphyrin and C 60 complexes, and are therefore related to the controllable performance of the new materials in applications. intramolecular charge transfer (ICT), triplet-triplet absorption, donor-acceptor compound