Fluorescence and photophysical properties of xylene isomers in water: with experimental and theoretical approaches

Khan, Muhammad Farooq Saleem; Wu, Jing; Liu, Bo; Cheng, Cheng; Akbar, Mona; Chai, Yidi; Memon, Aisha

doi:10.1098/rsos.171719

Cited by 19 publications

(8 citation statements)

References 45 publications

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“…The introduction of a methyl group at position 4 leads to a decrease in the oscillator strengths, whereas, on the other hand, the presence of methyl groups in positions 3, 5 and 6 results in a net enhancement of the predicted oscillator strengths. These results, being in good agreement with experimental findings (see the ESI section 4 for more details), follow the already reported trends with the 2AP analogs, 29,42,43 suggesting that the presence of the phosphoryl group does not significantly modify the way in which the methyl substitution of the aromatic ring affects the observed trend in the spectroscopic properties of the methyl substituted 2PAP derivatives.…”

Section: Validation Of the Methodologysupporting

confidence: 92%

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On the impact of a phosphoryl group in the recognition capabilities of 2-aminopyridines toward carboxylic acids

et al. 2019

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Inspired by natural molecular recognition processes, many research efforts have been routed in recent years towards the design of new host-guest molecular systems based on non-covalent interactions. Within this field, 2-aminopyridines (2APs) have been widely studied due to their tunable spectroscopic response in presence of carboxylic acids. Herein, we present and analyze a novel family of 2AP core compounds based on 2phosphorylamidopyridine (2PAP). Linear response timedependent density functional theory (TD-DFT) has been used to characterize and model several spectroscopic properties of 2PAP. Our results, validated through experiments, show that TD-DFT can provide a reliable description of the electronic excited states of these aromatic systems. In addition, we have also studied the amino-imino tautomerization of 2AP and 2PAP under the light of TD-DFT tools. We show that the presence of a carboxylic acid has a catalytic effect on the tautomerization reaction, which otherwise does not occur spontaneously at room temperature. These results suggest that this low-cost computational approach can be applied to more complex organic systems derived from 2-aminopyridine, paving the way for the development of potentially useful sensing materials and organic species for molecular recognition.

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Section: Validation Of the Methodologysupporting

confidence: 92%

“…Such deviation has already been previously described employing other computational methods in analogous systems. 29,43…”

Section: Validation Of the Methodologymentioning

confidence: 99%

On the impact of a phosphoryl group in the recognition capabilities of 2-aminopyridines toward carboxylic acids

et al. 2019

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“…The significant differences in quantum yield of the m -xylylenediamine and p -xylylenediamine polymers can be explained by the intrinsic fluorescent differences of the xylylenediamine monomers with the para isomer displaying fluorescence approximately 15 times greater than the meta isomer (Figures S17 and S18). The difference in monomer fluorescent intensity is further amplified by the increased rigidity (thus increased fluorescence), of the p -xylylenediamine repeating unit when incorporated into the polymer chain. The molecular mass of the copolymers has insignificant influence on the fluorescence intensity.…”

Section: Resultsmentioning

confidence: 99%

Unprecedented Enzymatic Synthesis of Perfectly Structured Alternating Copolymers via “Green” Reaction Cocatalyzed by Laccase and Lipase Compartmentalized within Supramolecular Complexes

Scheibel

Gitsov

2018

Biomacromolecules

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This study describes the first use of laccase–lipase enzymatic reaction for the synthesis of novel perfectly structured alternating copolymers. Initially, six types of complexing agents, linear(A)–linear(B), linear(A)–linear(B)–linear(A), linear–dendritic, dendritic–linear–dendritic, linear–hyperbranched, and hyperbranched–linear–hyperbranched amphiphilic block copolymers, are proven to significantly enhance enzyme activity of three different types of lipases - Penicillium camemberti, Candida rugosa, and Burkholderia cepacia (up to 1400%, 1700%, and 870% increase with respect to the native enzymes). The copolymerization is performed in several consecutive steps: (a) lipase and laccase are dissolved in aqueous medium at neutral pH; (b) a complexing agent is added leading to cocompartmentalization of the two enzymes within a micelle or physical network; (c) the two comonomers are introduced simultaneously to the tandem enzyme complex. The reaction proceeds in the following pathway: laccase catalyzes the oxidation of catechol to o-quinone followed by lipase comediated Michael addition of a diamine. While laccase could catalyze the entire process, addition of lipase is able to increase copolymer yield up to 30.7%. Addition of a complexing agent improves the yield further up to 67.9% (23.2% yield obtained for native laccase). Complexing agents significantly increase polymer molecular mass (M w = 130 900 vs 35 500 Da for the native enzymes reaction system). The resulting copolymers are highly fluorescent (quantum yield up to 0.733) and demonstrate pH sensitive behavior, properties that hint toward their potential as imaging agents.

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“…and where B ψ is a prefactor defined in terms of the coefficients c ψ i for each of the six HMO's Ψ i , the expressions for which are given in Appendix A 1 [44,45].…”

Section: Rate Calculationmentioning

confidence: 99%

Dark matter-electron scattering from aromatic organic targets

et al. 2020

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Sub-GeV dark matter (DM) which interacts with electrons can excite electrons occupying molecular orbitals in a scattering event. In particular, aromatic compounds such as benzene or xylene have an electronic excitation energy of a few eV, making them sensitive to DM as light as a few MeV. These compounds are often used as solvents in organic scintillators, where the de-excitation process leads to a photon which propagates until it is absorbed and re-emitted by a dilute fluor. The fluor photoemission is not absorbed by the bulk, but is instead detected by a photon detector such as a photomultiplier tube. We develop the formalism for DM-electron scattering in aromatic organic molecules, calculate the expected rate in p-xylene, and apply this calculation to an existing measurement of the single photo-electron emission rate in a low-background EJ-301 scintillator cell. Despite the fact that this measurement was performed in a shallow underground laboratory under minimal overburden, the DM-electron scattering limits extracted from these data are already approaching leading constraints in the 3-100 MeV DM mass range. We discuss possible next steps in the evolution of this direct detection technique, in which scalable organic scintillators are used in solid or liquid crystal phases and in conjunction with semiconductor photodetectors to improve sensitivity through directional signal information and potentially lower dark rates.

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Fluorescence and photophysical properties of xylene isomers in water: with experimental and theoretical approaches

Cited by 19 publications

References 45 publications

On the impact of a phosphoryl group in the recognition capabilities of 2-aminopyridines toward carboxylic acids

On the impact of a phosphoryl group in the recognition capabilities of 2-aminopyridines toward carboxylic acids

Unprecedented Enzymatic Synthesis of Perfectly Structured Alternating Copolymers via “Green” Reaction Cocatalyzed by Laccase and Lipase Compartmentalized within Supramolecular Complexes

Dark matter-electron scattering from aromatic organic targets

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