Unique CT emission from aryl terpyridine nanoparticles in aqueous Medium: A combined effect of excited state hydrogen bonding and conformational planarization

Chettri, Bimal; Jha, Satadru; Dey, Nilanjan

doi:10.1016/j.jphotochem.2022.114210

Cited by 15 publications

(8 citation statements)

References 31 publications

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“…It was fascinating to see how the presence of different polyaromatic signaling moieties can affect the sensitivity toward CN – ions. − To rationalize the experimental observations, we first energy minimized both compounds P1 and P2 in neutral and anionic (deprotonated) forms. The energy-minimized structure of P1 showed a nonplanar structure, where the tetrazole ring is present at 27° angle with the naphthalene moiety.…”

Section: Resultsmentioning

confidence: 99%

Fluorescent Nanoassembly of Tetrazole-Based Dyes with Amphoteric Surfactants: Investigation of Cyanide Sensing and Antitubercular Activity

Fernandes,

Kumari,

Sriram

et al. 2023

ACS Appl. Bio Mater.

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Tetrazole-based easily synthesizable fluorogenic probes have been developed that can form self-assembled nanostructures in the aqueous medium. Though the compounds could achieve detection of cyanide ions in apolar solvents, such as, THF, significant interference was observed from other basic anions, such as F–, AcO–, H2PO4 –, etc. On the other hand, a highly specific response was observed for CN– ions in the aqueous medium. However, the sensitivity was so poor that it could hardly be useful for real-life sample analysis. Interestingly, the co-assembly of such probe molecules with hydroxyethyl-anchored amphoteric surfactants could drastically improve the sensitivity toward CN– ions in water without dampening their excellent selectivity. Also, it was observed that the degree of fluorescence response for CN– ions depends on the nature of the polyaromatic scaffolds (naphthyl vs anthracenyl), the nature of the surfactant assembly (micelle vs vesicle), etc. The mechanistic investigation indicates the hydrogen bonding interaction between the tetrazole −NH group and cyanide ions in the aqueous medium, which can effectively change the electronics of the tetrazole unit, resulting in alteration in the extent of charge transfer interaction. Then, the biocompatible composite materials (dye-surfactant assemblies at different ratios) were tested for antituberculosis activity. Fortunately, in a few cases, the compositions were found to be as effective as the commercially available antituberculosis drug, ethambutol.

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Section: Resultsmentioning

confidence: 99%

Fluorescent Nanoassembly of Tetrazole-Based Dyes with Amphoteric Surfactants: Investigation of Cyanide Sensing and Antitubercular Activity

Fernandes,

Kumari,

Sriram

et al. 2023

ACS Appl. Bio Mater.

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“…On the other hand, a very broad emission band centered at ∼500 nm is suggestive of the association of the pyrene units of Pybpa . The excitation spectra for the two major emission bands were very distinct, showing that these two bands originated from distinct ground state species, monomers, and aggregates (Figure a). , However, no red-shifted band (∼500 nm) was observed in organic solvents, such as MeOH or THF, which rules out the possibility of self-assembly formation in such systems (Figure S1). Though a “turn-on” fluorescence response was observed when Zn 2+ was added to Pybpa in a methanol medium, it has been observed that a variety of metal ions, including Zn 2+ , had no or negligible effect on the emission intensity of Pybpa in the aqueous medium (Figure S2 & Figure c).…”

Section: Resultsmentioning

confidence: 99%

Improved Analytical Performance of an Amphiphilic Probe upon Protein Encapsulation: Spectroscopic Investigation along with Computational Rationalization

Paul

Mondal

Dey

2023

ACS Appl. Bio Mater.

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An easily synthesizable pyrene-based amphiphilic probe (Pybpa) has been developed, which exhibited no responses with metal ions in the pure aqueous medium despite possessing a metal ion-chelating bispicolyl unit. We believe that spontaneous aggregation of Pybpa in aqueous medium makes the ion binding unit not accessible to the metal ions. However, the sensitivity and selectivity of Pybpa toward Zn2+ ions drastically improve in the presence of serum albumin protein, HSA. The differences in the microenvironment inside the protein cavity, in terms of local polarity, and conformational rigidity might be attributing factors for that. The mechanistic investigations also suggest that there might be the involvement of polar amino acid residues that take part in coordination with Zn2+ ions. Pybpa shows no detectable spectroscopic changes with Zn2+ ions in aqueous medium in the absence of HSA. However, it can effectively recognize Zn2+ ions in the protein-bound form. Moreover, the photophysical behavior of Pybpa and its zinc complex have been investigated with DFT and docking studies. Noteworthy, such an unusual sensing aspect of Zn2+ exclusively in the protein-bound state and particularly in aqueous medium is truly rare and innovative.

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“…The titration studies also indicated that the present system can detect Cu 2+ ions as low as 7.8 ppb. Furthermore, the stoichiometry of the complex formed with Cu 2+ was calculated using the method of continuous variation or Job’s method. − The total molar concentration of Cu 2+ and PMHMP was held constant, but their mole fractions varied. The changes in absorbance were plotted against the mole fractions of these two components, and from the maximum, on the plot, we could predict 1:1 stoichiometry with Cu 2+ (Figure S2, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Dual-Mode Multiple Ion Sensing via Analyte-Specific Modulation of Keto–Enol Tautomerization of an ESIPT Active Pyrene Derivative: Experimental Findings and Computational Rationalization

2023

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A pyrene-based e xcited - state intramolecular proton transfer (ESIPT) active probe PMHMP was synthesized, characterized, and employed for the ppb-level, dual-mode, and high-fidelity detection of Cu2+ (LOD: 7.8 ppb) and Zn2+ ions (LOD: 4.2 ppb) in acetonitrile medium. The colorless solution of PMHMP turned yellow upon the addition of Cu2+, suggesting its ratiometric, naked-eye sensing. On the contrary, Zn2+ ions displayed concentration-dependent fluorescence rise till a 0.5 mole fraction and subsequent quenching. Mechanistic investigations indicated the formation of a 1:2 exciplex (Zn2+:PMHMP) at a lower concentration of Zn2+, which eventually turned into a more stable 1:1 (Zn2+:PMHMP) complex with an additional amount of Zn2+ ions. However, in both cases, it was observed that the hydroxyl group and the nitrogen atom of the azomethine unit were involved in the metal ion coordination, which eventually altered the ESIPT emission. Furthermore, a green-fluorescent 2:1 PMHMP–Zn2+ complex was developed and additionally employed for the fluorimetric analysis of both Cu2+ and H2PO4 – ions. The Cu2+ ion, owing to its higher binding affinity for PMHMP, could replace the Zn2+ ion from the preformed complex. On the other hand, H2PO4 – formed a tertiary adduct with the Zn2+–complex, leading to a distinguishable optical signal. Furthermore, extensive and organized density functional theory calculations were performed to explore the ESIPT behavior of PMHMP and the geometrical and electronic properties of the metal complexes.

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Unique CT emission from aryl terpyridine nanoparticles in aqueous Medium: A combined effect of excited state hydrogen bonding and conformational planarization

Cited by 15 publications

References 31 publications

Fluorescent Nanoassembly of Tetrazole-Based Dyes with Amphoteric Surfactants: Investigation of Cyanide Sensing and Antitubercular Activity

Fluorescent Nanoassembly of Tetrazole-Based Dyes with Amphoteric Surfactants: Investigation of Cyanide Sensing and Antitubercular Activity

Improved Analytical Performance of an Amphiphilic Probe upon Protein Encapsulation: Spectroscopic Investigation along with Computational Rationalization

Dual-Mode Multiple Ion Sensing via Analyte-Specific Modulation of Keto–Enol Tautomerization of an ESIPT Active Pyrene Derivative: Experimental Findings and Computational Rationalization

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