# Charge–Transfer Complexes and Fluorescence Modulation in Amide- and Carboxy-Substituted 2‑Phenyl-1,3,2-benzodiazaboroles

## TL;DR

This paper explores how substituting amide and carboxy groups affects the optical properties of a specific chemical compound, revealing potential uses in sensing and materials.

## Contribution

The study introduces new amide- and carboxy-substituted benzodiazaborole derivatives with tunable fluorescence and charge-transfer behavior.

## Key findings

- Several derivatives showed strong red-shifted fluorescence with large Stokes shifts.
- DFT calculations support the formation of antiparallel dimeric charge-transfer complexes.
- The compounds exhibit consistent absorbance but variable emission due to structural modifications.

## Abstract

A library of amide-
and carboxy- functionalized 2-phenyl-1,3,2-benzodiazaborole
derivatives was synthesized via microwave-assisted cyclic condensation
to explore the effects of pseudoaromaticity on charge-transfer complex
(CTC) formation and photophysical behavior. All compounds were characterized
by NMR, IR, UV–vis, and fluorescence spectroscopy. While absorbance
profiles remained consistent (λmax = 298 –
324 nm), several derivatives exhibited strong bathochromic emission
(λem = 363 – 555 nm) and exceptionally large
Stokes shifts (Δv > 150 nm), particularly
those
bearing –OCH3 groups. Red-shifted fluorescence and
DFT calculations suggest antiparallel dimeric CTCs stabilized by B–N
delocalization. These results highlight amide- and carboxy- 1,3,2-benzodiazaborole
frameworks as tunable pseudoaromatic systems with potential applications
in optical sensing and functional material design.