BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
4 results
Search Results
Item Aggregation-induced emission mechanism of styrene derivative: a theoretical study(RSC, 2025-05) Roy, Ram KinkarThe aggregation-induced emission (AIE) mechanism of the fluorescent styrene derivative 4-dimethylamino-2-benzylidene malonic acid dimethyl ester (BIM) in methanol solution is theoretically investigated using spin–flip long-range corrected time-dependent density functional theory (SF-LC-TDDFT). The potential energy surfaces (PESs) for the ground (S0) and first singlet excited (S1) states of BIM were calculated along the rotation of the aryl main axis (α angle rotation), consistent with experimental observations. For the monomer, our findings reveal a significant reduction in oscillator strength, approaching zero at the optimized geometry in the S1 state. As this state corresponds to a charge transfer state, it suggests that the BIM monomer operates as a twisted intramolecular charge transfer (TICT) system, undergoing quenching through α angle rotation. The restriction of TICT, and consequently the inhibition of fluorescence quenching in the aggregate state, is also investigated by extracting the coordinates of 13 monomers from the crystal structure of BIM. The α-torsional angle of the central monomer was manually rotated in both clockwise and anti-clockwise directions to assess the intramolecular restrictions within the constrained environment. This analysis reveals that even a 10° rotation of the α-torsional angle, in either direction, causes the atoms of the central monomer to come into close contact with the atoms of the neighboring monomers. These short contacts effectively inhibit the TICT process, thereby leading to aggregation-induced emission.Item Aggregation-induced emission: a curious case of molecular luminescence(Springer, 2024-11) Addy, Partha SarathiAggregation-induced emission (AIE) is an interesting luminescence phenomenon. This process describes how unity in the molecular world can produce bright emissions (luminescence). Chemists have adopted this technique to design various luminescent materials to develop efficient diagnostics and therapeutics. In this article, a concise description of AIE and its development is documented. The application of AIE is significant in the field of materials and biology. In the last part of the article, a brief description of various uses is presented.Item Aggregation induced emission based luminogenic (aiegenic) probes for the biomarker detection(Wiley, 2025-01) Addy, Partha SarathiVarious biomarkers such as proteins play key roles in controlling crucial biochemical processes. The critical concentration of the biomarkers is important to maintain a healthy life. In fact, imbalance in concentration or irregular activity of these can lead to various diseases like Cancer, Alzheimer's etc. Therefore, the disease related biomarkers and their timely detection are key to control the illness. In the literature, a few activity-based probes for the detection of such biomarkers are available. As per the requirement an ideal probe should be very specific to recognize the target analyte and that could be achieved by virtue of having a robust structure and stimuli responsive nature. In this regard, several fluorescent probes are of great choice. Although these fluorescent probes face certain challenges such as aggregation caused quenching, which heavily affects the sensitivity and photostability is another major concern for many fluorescent probes. To overcome these challenges aggregation-induced emissive fluorescent probes found to be an excellent alternative. Aggregation induced emissive luminogens (AIEgens) offer higher signal to noise ratios and found to possess better photostability during sensing and imaging. In the present review we have summarized the development of AIEgenic probes for sensing and imaging of disease related biomarkers. We believe this review could be a guide to design efficient AIEgenic probes for the diagnostics development.Item Dual-emissive iridium(iii) complex with aggregation-induced emission: mechanistic insights into electron transfer for enhanced hypoxia detection in 3D tumor models(ACS, 2025-01) Roy, Aniruddha; Laskar, Inamur RahamanAccurate oxygen detection and measurement of its concentration is vital in biological and industrial applications, necessitating highly sensitive and reliable sensors. Optical sensors, valued for their real-time monitoring, nondestructive analysis, and exceptional sensitivity, are particularly suited for precise oxygen measurements. Here, we report a dual-emissive iridium(III) complex, IrNPh2, featuring “aggregation-induced emission” (AIE) properties and used for sensitive oxygen sensing. IrNPh2 exhibits dual emissions at 450 and 515 nm, with 515 nm triplet-state emission demonstrating remarkable oxygen sensitivity due to its long-lived excited state (12.12 μs) and high quantum yield (68%). Stern–Volmer analysis reveals a notable quenching constant (Ksv = 12.44%–1) and an ultralow detection limit of 0.0397%, emphasizing its superior performance. The oxygen quenching mechanism is driven by electron transfer (ET), supported by computational studies showing the lowest-unoccupied molecular orbital (LUMO) alignment of IrNPh2 with the πg* orbitals of triplet oxygen, leading to superoxide radical (O2•–) formation. Electron paramagnetic resonance (EPR) studies further confirm this pathway. Biological evaluations using a three-dimensional (3D) U87-MG glioma spheroid model highlight the ability of IrNPh2 to detect hypoxic regions, with significant fluorescence enhancement under hypoxia and minimal cytotoxicity (>80% viability at 100 μM). With high sensitivity, low detection limits, and biocompatibility, IrNPh2 emerges as a promising candidate for oxygen sensing in environmental and biomedical applications, especially tumor hypoxia detection.