Research Projects

White light generation (WLG) has become an important topic of interest in bioimaging technology for fabricating white light transilluminators (WLT). On the other hand, WLG also gained popularity owing to its use in optoelectronic devices and displays. In this regard, Fluorescent Organic Nanoparticles (FONs) have stormed in to be used as white light generating materials. FONs exhibit tunable fluorescence, high quantum yield, and biocompatibility, making them a good candidate for bioimaging, sensing, and phototheranostics. When coupled with organic fluorogens, or even other FONs, they can generate white light. FONs, made from self-assembly in water, have shown significant potential in bioimaging and optoelectronics. When synthesized from the Single Benzene-Based Fluorophores (SBBF), these nanoparticles exhibit exceptional optical properties and biocompatibility, making them ideal for deep-tissue imaging and single-particle tracking. SBBFs are cheap and relatively simple to synthesize. Owing to their distinctive photophysical properties, e.g., solid state emission and high fluorescence quantum yield, SBBFs are also useful in optoelectronic applications. SBBFs, in general, are devoid of an extended π-conjugation. However, they do possess electron-donating and electron-withdrawing groups, which results in the modulation of the electronic band gaps. Hence, adjusting the donor and acceptor moieties may generate tunable emission in an SBBF and also help modulate the fluorescence quantum efficiency. 5-(tert-Butyl)-2-hydroxy-1,3-isophthalaldehyde (5-tBHI) is such an SBBF, which has been used as a scaffold to synthesize a variety of fluorescent probes, to be used in different fields of chemistry and biology, like cellular imaging, pH sensing, metal sensing, metal tracing, ion sensing, etc. Surprisingly, except for a single report by Tanaka et al., we could not find any report in the literature about the in-depth spectroscopy of this SBBF itself. We were the first to report about its complex photophysics (J. Mol. Liq. 2023, 390, 123161; Phys. Chem. Chem. Phys. 2024, 26, 6655). 5-tBHI shows solvent-dependent single or dual emission. This dual-emission behavior, influenced by the surrounding solvent environment, makes 5-tBHI a versatile candidate for the next-generation SBBF and beyond. Further, we established that 5-tBHI forms concentration-dependent aggregates of different order, due to which it shows a tunable, but quenched emission (J. Phys. Chem. B 2024, 128, 5437). Looking ahead, by harnessing the emissive properties of 5-tBHI, a transformative approach, based either on Förster Resonance Energy Transfer (FRET) process, or ‘sum emission process’ can be developed where 5-tBHI, or its derivatives, can be combined with other organic fluorogens, In fact, the preliminary data is found to be very promising, where white light generation is achieved from a 5-tBHI-Rhodamine B solution in presence of Al3+, while yellow light is generated from 5-tBHI-surfactant composite and Rhodamine B solution. Moreover, 5-tBHI also showed modulated fluorescence in the presence of human serum albumin-surfactant composite. Hence, systematic derivatization of 5-tBHI can pave the way for novel two-component, bright, white-light-emitting (WLE) photoluminescent material. This project also holds the promise where emission colour can be meticulously controlled by adjusting the composition and excitation wavelength. The proposed research aims to position 5-tBHI at the forefront of this evolution by further enhancing its red-emitting capabilities through derivatization and exploring its dual role both as a donor and an acceptor in WLE applications. In this regard, apart from the synthetic modification of 5-tBHI, we also seek to synthesize and study 5-tBHI-based, polymerization-mediated, PEGylated fluorescent nanoparticles (FNPs), which can offer enhanced fluorescence, better tunability, biocompatibility, and colloidal stability, which has never been tried before.