Multifunctional Receptor with Tunable Selectivity: A Comparative Recognition Profile of Organic Nanoparticles with Carbon Dots

Abstract

The exponential growth in the research field of water pollution control demands the evolution of novel sensing materials for regulation and quantification of metals ions. Within this context, the current work reports a new strategy for the synthesis of carbon dots from the hydrothermal treatment of organic nanoparticles. The organic nanoparticles are found to be selective towards Cs(I) ions with a detection limit of 5.3 nM, whereas the highly fluorescent carbon dots are found to be selective towards Ag(I) ions with a detection limit of 4.8 nM. Both sensing systems illustrate rapid sensing with a working pH range from 4–9. The interfacial molecular restructuring of the sensing systems in the aqueous phase has been investigated in the absence and presence of targeted metal ions using a sum frequency generation vibrational spectroscopic tool. The practical applicability of the sensors was checked in environmental samples. This work opens new avenues for the exploration of temperature‐guided sensing modulation in nanomaterials.

Green Synthesized Fluorescent Carbon Dots from Momordica charantia for Selective and Sensitive Detection of Pd2+ and Fe3+

“…The characteristic absorption of CDs around 318 nm was likely attributed to n-π* transition of the C=O bond. [36,38] The band at 272 nm corresponded to n-π* electronic transition of the carbonyl group [37,38] while the band at 247 nm might be assigned to ππ* transitions of C=C bonds, [37] respectively. The diluted CDs solution was pale yellow in the daylight (inset, Figure 3(b) left) and fluorescence spectra exhibited bright blue color under UV excitation at 365 nm (inset, Figure 3(b) right).…”

Elucidating the Molecular Mechanism of Drug–Polymer Interplay in a Polymeric Supersaturated System of Rifaximin

“…We used SFG spectrometer (Ekspla, Lithuania) to probe the drug–polymer interactions at the air–aqueous interface. The SFG experimental setup used for the present work is described previously in detail. − It is comprised with a passively mode-locked Nd:YAG laser (Ekspla PL2231). The output of the laser beam consisted of 30 ps pulse with a repetition rate of 50 Hz at a wavelength as 1064 nm with energy as 40 mJ.…”

“…SFG is a second-order nonlinear optical spectroscopic technique used to examine various interfaces to provide the molecular level insight about various interactions and the interfacial structure of the molecules residing at the interfacial region. − The SFG signal (ω SFG ) is generated after fulfilling the spatial and temporal overlapping of two input beams visible (ω VIS ) and the tunable infrared (IR) (ω IR ) at the air–aqueous interface. A schematic representation of SFG spectroscopy is given in Figure .…”

“…The interfacial molecular behavior is quite distinct due to the interfacial asymmetric environment as compared to the centrosymmetric molecular environment of the bulk phase. , The intensity of the SFG signal increases when the frequency of the input tunable IR radiation corresponds to the natural vibrational frequency of the interfacial molecule . The observed intensity of the SFG beam is proportional to the squared modulus of second-order nonlinear susceptibility (χ (2) ) and the intensity of both visible ( I VIS ) and IR ( I IR ) input pump beams, and it is given as eq . ,,, …”

“…30 The observed intensity of the SFG beam is proportional to the squared modulus of second-order nonlinear susceptibility (χ (2) ) and the intensity of both visible (I VIS ) and IR (I IR ) input pump beams, and it is given as eq 5. 22,25,27,31…”