Design and Synthesis of Novel Chromophore with Multi-Carboxyl Groups

ABSTRACT

In order to explore the application of organic conjugated small molecules in bioimaging, a novel functional chromophore with A-π-D-π-A structure (Cr-3) was synthesized through Knoevenagel condensation reaction, consisting of carbazole unit as electron donor and cyanoacetic acid as electron acceptor groups. To improve the water solubility of this conjugated molecule, three carboxyl groups were introduced to chromophore Cr-3. Compared to the traditional D-π-A chromophores, chromophore Cr-3 showed the great improvement in water with the solubility of 2000 ppm. Also, the thermal stability of chromophore Cr-3 was also studied. The thermal decomposition temperature (Td) of Cr-3 was approximately 180°C, which was attributed to the dehydration of the carboxyl groups. Though the second harmonic generation (SHG) effect was not very high, it is large enough for the detection of SHG signal in water solution (0.28 pm/V).

KEYWORDS:

• Chromophore
• multi-carboxyl
• second-order nonlinear optics
• water solubility

Funding

This work was supported by Special Nonprofit Agricultural Industrial Research Fund of China (20080321, 201103027).