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

• Luminescent 5-aryl-tetrahydrodibenzo[a,i]phenanthridines were developed by modified synthetic protocol using SnCl2.
• The donor and acceptor groups significantly induced the charge transfer character leading to widespread emission properties.
• The protonation studies showed hyperchromic effect, which can be used in fluorescence-based sensor applications.
• Further, tetrahydrodibenzo[a,i]phenanthridines based chromophores exhibit wide optoelectronic applications.

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.

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