Spectral tuning of the phosphorescence from metalloporphyrins attached to gold nanorods.

The spectral shape of the phosphorescence emission of organometallic porphyrin molecules is shown to be altered when these chromophores are incorporated into hybrid nanostructures with gold nanorods. This result shows that triplet-singlet transitions, which are (at least partially) dipolar forbidden, can be modified by the dipolar resonances of gold nanoparticles. By choosing nanorods of increasing aspect ratios, it is possible to match the long axis plasmon resonance of the nanorods to a specific phosphorescence transition. Consequently, the emission colour of the hybrids can be tuned.