Department of Chemistry

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1924

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Engineering dielectric and metallic metasurfaces for sensing applications in the near-infrared region
(SPIE, 2024) Grover, Nitika; Arora, Pankaj
Dielectric and metallic metasurfaces are proposed to demonstrate the sensing applications in the near-infrared region under normal incidence light. The geometrical parameters of the proposed metasurfaces are designed using Rigorous coupled analysis under wavelength interrogation, and the results are verified using Comsol Multiphysics software. A layer of 2D nanomaterial (MoS2) is considered to increase the adsorption on the sensing surface. Aluminum-based metallic metasurfaces offer a sensitivity of 1100nm/RIU with a figure of merit of 250 RIU-1. The proposed metasurfaces are further used for the detection of cancer cells in human blood, and a red shift in the wavelength spectra is observed due to the increase in the refractive index.
Investigation of aluminum-based plasmonic devices for sensing applications in the near-infrared region
(SPIE, 2024-03) Arora, Pankaj; Grover, Nitika
We present surface plasmon resonance-based sensing devices with Aluminum (Al) as the plasmonic metal in the near-infrared region and analyze the output performances in terms of higher sensitivity and the Figure of Merit (FOM). The optical characteristics of Al-based plasmonic sensors are explored using different interrogation modes (angle and wavelength). Biorecognition elements help to enhance the sensor’s performance, for which 2D nanomaterials are explored for the biofunctionalization of the top surface. In the end, we also present an Al-based plasmonic device that utilizes both prism and nanostructure-based configurations, and the same designed parameters for the device offer high sensitivity and FOM in both angle and wavelength interrogation.
Meso-substitution controlled synthesis of bodipy–dpm conjugates: a pathway to tailored photophysical properties
(2026) Roy, Aniruddha; Arora, Pankaj; Grover, Nitika
We show that the electronic nature of the meso-aryl substituent in 1,3,5,7-tetramethyl BODIPYs governs the reactivity of the 1,7-methyl (α-methyl) groups toward the Knoevenagel condensation. Reaction of pyrrole-2-aldehyde with electron-deficient 1,3,5,7-tetramethyl-meso-pentafluorophenyl and 1,3,5,7-tetramethyl-meso-4-nitrophenyl BODIPYs yields double condensation at the 1,7-methyl positions to give the corresponding bis(pyrrole) derivatives, whereas the electron-rich meso-tolyl analogue selectively undergoes single condensation at only one of the α-methyl groups under identical conditions. This substituent-dependent divergence extends to reactions with 1,9-diformyl-meso-aryl dipyrromethanes, enabling access to structurally distinct BODIPY–DPM conjugates. Reaction of 1,9-diformyl-DPM with meso-tolyl BODIPY selectively yields acyclic monosubstituted BODIPY–DPM conjugates, whereas the higher reactivity of meso-pentafluorophenyl BODIPY enables condensation between both 1,7-methyl groups and the two aldehyde functionalities of the diformyl-DPM scaffold, affording cyclic, porphyrin-like BODIPY–DPM frameworks. Notably, meso-pentafluorophenyl BODIPYs also undergo nucleophilic aromatic substitution of the para-fluorine atom by piperidine under the condensation conditions, as confirmed unambiguously by single-crystal X-ray diffraction. The resulting BODIPY–DPM and BODIPY–pyrrole conjugates exhibit pronounced bathochromic shifts (90–180 nm relative to parent BODIPYs), deep-red to near-infrared absorption (~670 nm) and emission (~750 nm), enlarged Stokes shifts, and strong intramolecular charge-transfer character. These features translate into efficient heavy-atom-free triplet formation, with singlet-oxygen quantum yields reaching up to 0.45. A representative conjugate (10) exhibits potent photodynamic activity in B16F10 melanoma cells with minimal dark toxicity (IC₅₀ = 0.95 μM). TD-DFT analysis indicates that excited-state twisting reduces ΔEST, thereby facilitating heavy-atom-independent intersystem crossing. Collectively, these results establish a robust molecular design framework for next-generation heavy-atom-free photosensitizers.
TiO2-FG-based plasmonic sensor with enhanced figure of merit for sensing applications: A numerical approach
(Elsevier, 2025-09) Grover, Nitika; Arora, Pankaj
A refractive index-based surface plasmon resonance sensor using a multilayer heterostructure in the Kretschmann configuration is proposed for the near-infrared region. In the proposed configuration, aluminum is used as a plasmonic metal, titanium dioxide is used as a dielectric layer, and a fluorinated graphene (FG) layer is used as a 2D nanomaterial to enhance the performance parameters. A thorough comparative study is conducted between popularly used titanium compounds: Titanium dioxide (TiO2) and Titanium disilicide (TiSi2). For the proposed SPR sensor, each layer is engineered and optimized on the grounds of linewidth, detection accuracy (DA), and Figure of Merit (FOM), which are the critical performance parameters. To this end, the geometrical parameters are calculated using the transfer matrix method and analyzed meticulously to find the optimum trade-off points. The proposed sensor is numerically tested efficiently to sense different concentrations of hemoglobin in human blood. For the angle interrogation technique at the wavelength of 1550 nm, the sensor provides an enhanced FOM of 462.8 RIU−1 and a DA of 4 degrees−1. Thus, the proposed design opens a broader window for bio-sensing applications because of the advantages TiO2 and FG layers offer in enhancing the sensing parameters.
Ultrasensitive surface plasmon resonance-based biosensor for efficient detection of SARS-CoV-2 Virus in the near-infrared region
(2024) Grover, Nitika; Arora, Pankaj
This work offers an ultra-sensitive multilayered surface plasmon resonance (SPR)-based biosensor that uses angular interrogation in the near-infrared (NIR) region to detect the novel coronavirus (SARS-CoV-2). The multi-layered biosensor consists of the bimetallic layer (Aluminum (Al) & Gold(Au)), a dielectric layer (MgF2), and an optimized number of 2D nanomaterial (MoS2) layers. The proposed SPR sensor is engineered using the transfer matrix and finite element methods to achieve high sensitivity, the figure of merit (FOM), and detection accuracy. The selection of plasmonic metal and optimization for the different layers have been proved crucial to improving the performance parameter of the proposed sensor. The biosensor configuration (Glass prism/Al/Au/MgF2/MoS2/sensing sample) is observed to exhibit the highest sensitivity of 372°/RIU, FOM of 1690 RIU-1, and detection accuracy of 4.54 degree-1 using the strong binding efficiency of the MoS2 layer and the high dielectric constant of the MgF2 layer. According to the investigation's findings, the proposed SPR-based biosensor exhibits excellent performance in the NIR region, demonstrating accurate real-time detection capabilities that will facilitate its use in field or clinical point-of-care testing applications.