SYNTHESIS AND OPTICAL PROPERTIES OF AZA-BODIPY SUBSTITUTED BY THIOPHENE DERIVATIVES

Abstract

Novel thienyl aza-BODIPY derivatives were successfully synthesized by means of aza-dipyrromethene core condensations. The syntheses were carried out via 4 steps: Friedel-Crafts acylation, Michael addition, condensation to yield aza-dipyrromethene, which was then complexed with boron trifluoride etherate. The thienyl phenyl aza-BODIPY (4,TPAB) parent was obtained from the 4-step procedure as black blue solid in 5 % overall yield. The novel 1,7-hexyloxy phenyl derivative of thienyl alkoxyphenyl aza-BODIPY (17,TAAB) was obtained in 0.8 % overall yield. The 1,7-phenyl-3,5-(3’,4’-ethylenedioxy-2’-thienyl)-BODIPY (EDOT-phenyl BODIPY, 9, EPB) was obtained instead of the desired aza-BODIPY analog in 0.4 overall yield. The characterizations of TAAB and EPB by UV-Vis spectra and fluorescent spectra exhibited the relative bathochromic shift of absorption maxima and emission maxima compared to those of the corresponding thienyl phenyl parents. This shift supported the hypothesis that the presence of alkoxy groups on the phenyl rings at 1,7-positions and conjugated 3,4-ethylenedioxythiophene (EDOT) at 3,5-positions could decrease the HOMO–LUMO gap, which is attributed to an enhancement of the planarity and electron mobility of the π-conjugated system.