Abstract:
NIR (Near infrared region) fluorescent molecules like aza-BODIPYs are highly fluorescent and they emit in the NIR region, so this class of molecules are potentially useful as probes for biotechnology. Some modification can be done in aza-BODIPY core to make it emit above 700 nm. It can be achieved by adding more electron donating group, rigidifying substituents around the core and also extending the conjugation of the system. A novel series of pyrene based aza-BODIPYs are synthesized and characterized under this project. The donor moieties at 1,7- position of aza-BODIPY is fixed that is pyrene, only the 3,5- position is varied. It includes phenyl, thiophene and 4-methoxy phenyl group. Photophysical and optical studies of the aza-BODIPYs were carried out. These molecules are showing significant bathochromic shifts in both absorption maxima and emission maxima compared to the parent 1,3,5,7-tetraphenyl-aza-BODIPY (TPAB) because of combined effect of both the extension of the π-conjugation and the rigidization. Moreover a large Stokes shift (>100 nm) is observed in case of BODIPY where 1,7 position are substituted by pyrene and 3,5 position are substituted by phenyl.