Meso-substituted Porphyrin Derivatives via Palladium-Catalyzed Amination Showing Wide Range Visible Absorption: Synthesis and Photophysical Studies

In recent years, there has been a growing interest in
the design
and synthesis of chromophores, which absorb in a wide region of the
visible spectrum, as these constitute promising candidates for use
as sensitizers in various solar energy conversion schemes. In this
work, a palladium-catalyzed coupling reaction was employed in the
synthesis of molecular triads in which two porphyrin or boron dipyrrin
(BDP) chromophores are linked to the meso positions of a central Zn
porphyrin (PZn) ring via an amino group. In the resulting
conjugates, which strongly absorb over most of the visible region,
the electronic properties of the constituent chromophores are largely
retained while detailed emission experiments reveal the energy transfer
pathways that occur in each triad.