Tuning the Emission Color of Indolo[3,2‐<i>b</i>]carbazole‐Based Boron Complexes and their Application in Organic Field Effect Transistors and Bioimaging
Mrunesh Koli, Amina Labiod, Saikat Chakraborty, Mukesh Kumar, Patrick Lévêque, Gilles Ulrich, Nicolas Leclerc, Denis Jacquemin, Soumyaditya Mula
Abstract
Abstract Synthetic strategies were developed for the preparation of indolo‐imine boron difluoride (IIBD) dyes based on indolo[3,2‐ b ]carbazole structures. Four new IIBD dyes were synthesized and were subsequently converted into the corresponding ‐BPh 2 /‐BOR 2 and N‐ t ‐Boc/N‐benzoyl derivatives. The photophysical properties of all dyes were determined in both solution and solid media. All dyes absorb in the UV/Vis region, show negative solvatochromism, and are fluorescent in both media. The absorbance and fluorescence properties of the dyes can be tuned over a wide range by synthetic modifications. These findings are rationalized by theoretical calculations that correspond well to the experimental shifts, explain the negative solvatochromism, and allow quantification of charge transfer (CT). Similarly, the HOMO–LUMO energies measured by CV are in good agreement with the theoretically calculated values. Interestingly, the energy gaps of the dyes can also be tuned by structural modulations using the developed chemical route. Charge transport properties of the dyes were checked and showed that the N‐benzoyl derivative has the highest hole mobility which is useful for organic field effect transistor (OFET) applications. In addition, easy cellular uptake of the dyes, their low toxicity and high stability inside the cells associated with bright fluorescence in the cytoplasm will be useful for their future application as cellular imaging agents. All of these aspects highlight the interest of this new class of dyes.