文摘
Efficient light harvesting for molecular-based solar-conversion systems requires absorbers that span the photon-rich red and near-infrared (NIR) regions of the solar spectrum. Reported herein are the photophysical properties of a set of six chlorin-imides and nine synthetic chlorin analogues that extend the absorption deeper (624鈥?14 nm) into these key spectral regions. These absorbers help bridge the gap between typical chlorins and bacteriochlorins. The new compounds have high fluorescence quantum yields (0.15鈥?.34) and long singlet excited-state lifetimes (4.2鈥?0.9 ns). The bathochromic shift in Qy absorption is driven by substituent-based stabilization of the lowest unoccupied molecular orbital, with the largest shifts for chlorins that bear an electron-withdrawing, conjugative group at the 3-position in combination with a 13,15-imide ring.