New low band gap compounds comprised of naphthalene diimide and imine units

作者：Schab Balcerzak Ewa^*; Grucela Zajac Marzena; Krompiec Michal; Niestroj Anna; Janeczek Henryk

来源：Synthetic Metals, 2012, 162(5-6): 543-553.

DOI：10.1016/j.synthmet.2012.01.016

• Polyimides
• Polynaphthaleneimides
• Azomethines
• Azomethine-naphthalene diimides
• Electrochemistry
• Photoluminescence

New arylene bisimide derivatives, both low molecular compounds and polymers consisting of a naphthalene diimide core and imine linkages were synthesized. The azomethine-diimides were prepared from N,N%26apos;-bis(4-amino-2,3,5,6-tetramethylphenyl)naphthalene-1,4,5,8-dicarboximide (DANDI) which was condensed with 4-pyridinecarboxaldehyde or 1,3-benzothiazole-2-carboxaldehyde or 2-thiophenecarboxaldehyde or 2,2%26apos;-bithiophene-5-carboxaldehyde. Poly(azomethine-naphthaleneimide)s were obtained by high temperature polycondensation of DANDI with 2,5-thiophenedicarboxaldehyde or 2,2%26apos;-bithiophene-5,5%26apos;-dicarboxaldehyde. The materials do not show decomposition below 300 degrees C. The azomethine-diimides exhibited glass-forming properties with glass transition temperatures in the range of 80-195 degrees C. For the first time, to the best of our knowledge, amorphous molecular naphthalene diimide compounds were obtained. Optical properties of the prepared compounds were investigated by UV-vis and photoluminescence (PL) measurements. Most of the azomethine-diimides emitted green light with the highest intensity with emission maximum (lambda(em)) at ca. 519-535 nm contrary to polymers which lambda(em) was at 450 and 485 nm. All the compounds are electrochemically active and azomethine-diimides undergo quasi-reversible reduction and irreversible oxidation as evidenced by cyclic voltammetry (CV). In all studied molecules the electrochemically determined HOMO level is in the range of -5.5 to -5.13 eV whereas the LUMO level is close to -4.0 eV for azomethine-diimides and -3.8 eV for polymers as determined by differential pulse voltammetry (DPV). The investigated compounds exhibited low electrochemical band gap (1.21-1.5 eV) being promising for optoelectronic applications.

• 出版日期2012-4