Block modification of rod-shaped π conjugated carbon frameworks with donor and acceptor groups toward highly fluorescent molecules: synthesis and emission characteristics?

Organic & Biomolecular Chemistry Pub Date: 2008-02-27 DOI: 10.1039/B717832H

Abstract

To create organic molecules that are highly fluorescent at a longer wavelength region, we investigated the synthesis (using Pd-catalyzed cross-coupling) and photophysical properties (Φf, λem, τ, λabs, and ε) of the following π conjugated molecular rods consisting of p-phenyleneethynylene units modified by donor (OMe) and/or acceptor (CN) groups: (1) side-donor modification systems (SD systems), (2) side-acceptor modification systems (SA systems), and (3) systems consisting of a donor block and an acceptor block (BL systems). As a consequence, very high Φf values (>0.95) were obtained for BL systems. Bathochromic shifts of λem for the same π conjugation length were largest for BL systems. Thus we succeeded in creating highly efficient light emitters at a longer wavelength region by block modification (e.g., Φf = 0.97, λem = 464 nm for BL-9). Considerably intense solid emission (Φf ～ 0.5) at a longer wavelength region (500–560 nm) was also found for BL systems. It has been found that BL-6 and BL-8 exhibit interesting two photon absorption characteristics.

Graphical abstract: Block modification of rod-shaped π conjugated carbon frameworks with donor and acceptor groups toward highly fluorescent molecules: synthesis and emission characteristics
Recommended Literature