Synthesis, photophysical and acidochromic properties of a series of tetrahydrodibenzo[a,i]phenanthridine chromophores

A series of luminescent 5-aryl-tetrahydrodibenzo[a,i]phenanthridines was developed through modified synthetic protocol using SnCl2-acetic acid as a catalyst. The synthesis was consistent with various functionalities and significantly improves the yields. These derivatives exhibit large molar absorption coefficients and higher Stokes shift values in the range 9739-2628 cm(-1). The donor and acceptor groups significantly induced the charge transfer character leading to widespread emission properties in the range of 390-531 nm with moderate quantum yields. The protonation and quaternization studies of these derivatives revealed the formation of a new red shifted absorption band followed by hyperchromic effect in emission, which could be used as an acidochromic sensor. (C) 2016 Elsevier Ltd. All rights reserved.