Ultrafast Excited-State Proton Transfer in 4-Nitrocatechol: Implications for the Photochemistry of Nitrophenols DOI
Avery B. Dalton, Dmitry A. Fishman, Sergey A. Nizkorodov

et al.

The Journal of Physical Chemistry A, Journal Year: 2023, Volume and Issue: 127(40), P. 8307 - 8315

Published: Sept. 29, 2023

Nitrophenols are a class of environmental contaminants that exhibit strong absorption at atmospherically relevant wavelengths, prompting many studies their photochemical degradation rates and mechanisms. Despite the importance reactions nitrophenols in environment, ultrafast processes electronically excited not well understood. Here, we present an experimental study electron dynamics 4-nitrocatechol (4NC), common product biomass burning fossil fuel combustion. The experiments accompanied by time-dependent quantum mechanical calculations to help assign observed transitions static transient spectra estimate singlet-to-triplet intersystem crossing. Our results suggest electronic triplet states efficiently populated upon 340 nm excitation, as efficient proton transfer occurs state on time scale few picoseconds water tens 2-propanol. This suggests do play significant role 4NC environment and, extension, general. Instead, consideration should be given idea this molecules may serve photoacids.

Language: Английский

The Role of Aqueous Solvation on the Intersystem Crossing of Nitrophenols DOI Creative Commons
Eva Vandaele, Momir Mališ, Sandra Luber

et al.

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: 20(8), P. 3258 - 3272

Published: April 12, 2024

The photochemistry of nitrophenols is a source smog as nitrous acid formed from their photolysis. Nevertheless, computational studies the these widespread toxic molecules are scarce. In this work, initial photodeactivation

Language: Английский

Citations

5
Investigation of m-NP and p-NP adsorption from single and binary aqueous solutions onto Al2O3 and HDTMA+/Al2O3 composite using first derivative UV/Visible spectrophotometry DOI
Mustapha Aazza, Hammou Ahlafi

Journal of Molecular Liquids, Journal Year: 2024, Volume and Issue: 398, P. 124220 - 124220

Published: Feb. 9, 2024

Language: Английский

Citations

4
Fluorescence Probes Based on Aminoboranes for the Detection of Fluoride Ions and Nitroaromatics: A Bifunctional Fluorescence Detection Platform DOI
Ruhong Li, Zhiyuan Chen,

Lai Hu

et al.

Luminescence, Journal Year: 2025, Volume and Issue: 40(4)

Published: April 1, 2025

ABSTRACT Small‐molecule‐based fluorescent probes have garnered significant attention because of their excellent optical properties. Among these, multi‐stimuli‐responsive molecular been rapidly developed for wide range applications. In this study, we designed a bifunctional probe based on three‐coordinate boron compounds to detect fluoride ions and 4‐nitrophenol. Two NB1 NB2 , containing B‐mesityl 2 acceptors (A) nitrogen‐containing aromatic donors (D), were confirmed via single‐crystal X‐ray diffraction. The donor–acceptor (D–A) structure substantial steric hindrance enable these exhibit efficient fluorescence emission in both liquid solid states. Leveraging the properties boron, two visible rapid response ions, with detection limits 0.41 μM 1.31 . mechanism was corroborated by 19 F NMR spectra. Moreover, owing D–A B–N unit, 4‐nitrophenol, resulting from interrupted charge transfer. These serve as outstanding bifunctionality, stability, high efficiency. Given growing demand probes, possess great potential future sensing

Language: Английский

Citations

0
Femtosecond to Microsecond Observation of Photochemical Pathways in Nitroaromatic Phototriggers Using Transient Absorption Spectroscopy DOI Creative Commons

William A. Whitaker,

Deborin Ghosh, Partha Malakar

et al.

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(29), P. 5892 - 5905

Published: July 11, 2024

The synthetic accessibility and tolerance to structural modification of phototriggered compounds (PTs) based on the ortho- nitrobenzene (ONB) protecting group have encouraged a myriad applications including optimization biological activity, supramolecular polymerization. Here, combination ultrafast transient absorption spectroscopy techniques is used study multistep photochemistry two nitroaromatic phototriggers ONB chromophore, O-(4,5-dimethoxy-2-nitrobenzyl)-l-serine (DMNB-Ser) O-[(2-nitrophenyl)methyl]-l-tyrosine hydrochloride (NB-Tyr), in DMSO solutions femtosecond microsecond time scales following UV light. From common nitro-S1 excited state, PTs can either undergo state intramolecular hydrogen transfer (ESIHT) an aci-S1 isomer within singlet manifold, leading direct S1 → S0 internal conversion through conical intersection, or competitive intersystem crossing (ISC) access triplet manifold (1.93 ± 0.03) ps (13.9 1.2) for DMNB-Ser NB-Tyr, respectively. Deprotonation aci-T1 species yield anions proposed occur both PTs, with illustrative constant (9.4 0.7) ns DMNB-Ser. More than 75% photoexcited molecules return their electronic ground states 8 μs, by relaxation anion reprotonation. Hence, upper limits quantum yields photoproduct formation are estimated be range 13–25%. Mixed DMSO/H2O solvents show influence environment observed photochemistry, example, revealing lifetimes 10:1 mixture 1.95 (10.1 ps, which attributed different microsolvation environments.

Language: Английский

Citations

1
Competing Nonadiabatic Relaxation Pathways for Near-UV Excited ortho-Nitrophenol in Aqueous Solution DOI Creative Commons
Hallam J. M. Greene, Deborin Ghosh, Igor V. Sazanovich

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 15(36), P. 9153 - 9159

Published: Aug. 29, 2024

Nitrophenols are atmospheric pollutants found in brown carbon aerosols produced by biomass burning. Absorption of solar radiation these nitrophenols contributes to radiative forcing, but quantifying this climate impact requires better understanding their photochemical pathways. Here, the photochemistry near-UV (λ = 350 nm) excited ortho-nitrophenol aqueous solution is investigated using transient absorption spectroscopy and time-resolved infrared over fs μs time scale characterize states, intermediates, photoproducts. Interpretation data supported quantum chemical calculations linear-response time-dependent density functional theory (LR-TDDFT). Our results indicate efficient nonradiative decay via an S1(ππ*)/S0 conical intersection leading hot ground state which vibrationally cools solution. A previously unreported minor pathway involves intersystem crossing near S1(nπ*) minimum, with resulting triplet facilitated deprotonation. These relaxation pathways account for low yields photodegradation.

Language: Английский

Citations

1
Efficient Ground-State Recovery of UV-Photoexcited p-Nitrophenol in Aqueous Solution by Direct and Multistep Pathways DOI Creative Commons
Deborin Ghosh, K. Eryn Spinlove, Hallam J. M. Greene

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(44), P. 30443 - 30454

Published: Oct. 25, 2024

Nitroaromatic compounds are found in brown carbon aerosols emitted to the Earth's atmosphere by biomass burning, and important organic chromophores for absorption of solar radiation. Here, transient spectroscopy spanning 100 fs–8 μs is used explore pH-dependent photochemical pathways aqueous solutions p-nitrophenol, chosen as a representative nitroaromatic compound. Broadband ultrafast UV–visible infrared probes characterize excited states intermediate species involved multistep photochemistry, determine their lifetimes under different pH conditions. The assignment bands, dynamical interpretation our experimental measurements supported computational calculations. After 320 nm photoexcitation first bright state, which has 1ππ* character Franck–Condon region, (∼200 fs) structural relaxation adiabatic S1 state region with 1nπ* electronic character, p-nitrophenol population decays on time scale ∼12 ps. This decay involves competition between direct internal conversion S0 (∼40%) rapid intersystem crossing triplet manifold (∼60%). Population T1-state excited-state proton transfer (ESPT) surrounding water resulting triplet-state p-nitrophenolate anion its ground ∼5 ns. Reprotonation S0-state recovers state. Overall recovery via these competing close 100% efficient. observations help explain why such resist photo-oxidative degradation environment.

Language: Английский

Citations

1
Excited-State Decay and Photolysis of O-Nitrophenol after Proton Transfer. II: A Theoretical Investigation in the Microsolvated Atmospheric Environment DOI

Bo‐Wen Yin,

Jie‐Lei Wang,

Jia-Ling Dai

et al.

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(43), P. 9486 - 9496

Published: Oct. 17, 2024

Changes in atmospheric humidity affect the number of water molecules surrounding o-nitrophenol (ONP), creating an anisotropic chemical environment. It, turn, influences photodynamic behaviors ONP, differing from those observed gas phase and solution. Recently, we explored excited-state decay generation hydroxyl (OH) radical before proton transfer ONP microsolvated environment using MS-CASPT2//CASSCF approach. As is well known, capable converting to its aci-nitro isomer (aciONP) via intramolecular (ESIPT) process. In present work, photoinduced dynamics aciONP, which can lead OH nitrous acid (HONO), was studied same computational model. Our calculations demonstrated that increasing affects molecular geometries, particularly key bond lengths dihedral angles HONO group, while also reducing relative energies minima intersections. Moreover, identified two distinct types minimum structures: one retains hydrogen other breaks with H atom flipping outward. The latter structure, compared former, has a different electronic-state character facilitates intersystem crossing processes. Subsequently, major paths were proposed: (PATH I) ESIPT → S1 S1S0 S0; II) S1-2 S1T1 T1 S0T1 S0. Furthermore, state relatively long lifetime, allowing for formation HONO, corresponding energy barriers decrease as increases. These theoretical findings provide valuable insights into photodynamics aciONP

Language: Английский

Citations

0
Excited-State Decay and Photolysis of O-Nitrophenol before Proton Transfer. I: A Theoretical Investigation in the Microsolvated Atmospheric Environment DOI

Pei‐Ke Jia,

Jie‐Lei Wang,

Ruirui Zhao

et al.

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(43), P. 9497 - 9509

Published: Oct. 19, 2024

As a potential source of the hydroxyl (OH) radical and nitrous acid (HONO), photolysis

Language: Английский

Citations

0
Superior Photostability of the Unnatural Base 6-Amino-5-nitropyridin-2-ol: A Case Study Using Ultrafast Broadband Fluorescence, Transient Absorption, and Theoretical Computation DOI
Qingwu Xiong, Ping Wang, Chensheng Ma

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 15(46), P. 11553 - 11561

Published: Nov. 11, 2024

6-Amino-5-nitropyridin-2-ol (Z), a nitroaromatic compound and base for Hachimoji nucleic acids, holds significant potential in expanding the genetic alphabet, as well synthetic biology biotechnology. Despite its promising applications, spectral characterization photoinduced properties of Z have remained largely unexplored until now. This study presents comprehensive investigation into excited state dynamics various solvents, utilizing state-of-the-art ultrafast broadband time-resolved fluorescence transient absorption spectroscopy, complemented by computational methods. The acquired results provide direct experimental evidence that, upon photoexcitation, emits prompt from nearly planar structure state, independent solvent properties. deactivates nonradiatively within sub-picoseconds through internal conversion with unitary yield, primarily mediated rotation nitro group. unusually rapid deactivation pathway entirely excludes involvement long-lived nπ* states, triplet photoproducts, which are commonly observed most compounds natural DNA RNA bases. Our findings underscore that Z, an unnatural base, exhibits superior photostability compared to canonical provides valuable insights photodynamics compounds, is beneficial strategic substitution design environmental biological applications.

Language: Английский

Citations

0
Deciphering the Photocatalysis Mechanism of Semimetallic Bismuth Nanoparticles DOI Creative Commons
Lauren Hoffman,

Delaney J. Hennes,

Pin Lyu

et al.

The Journal of Physical Chemistry C, Journal Year: 2024, Volume and Issue: 128(47), P. 20118 - 20128

Published: Nov. 16, 2024

Metallic nanoparticle photocatalysts have been developed in various catalytic systems over the past few decades, including diverse noble and non-noble metals with plasmonic properties. The hot-carrier-induced mechanism is one of most appealing pathways as it can provide energetic electrons or holes for driving thermodynamically unfavorable reactions increasing reaction rate. In this work, we evaluate photocatalytic performance semimetallic bismuth nanoparticles offer detailed mechanistic interpretations terms hot carriers interband transitions. photocatalyzed nitrophenol reduction sodium borohydride serves a model reaction, wavelength-dependent study reveals contribution carriers. It demonstrated that light irradiation under shorter wavelengths could produce deeper nanoparticles, which be quenched more effectively by hole scavengers, thus facilitating electron-transfer process resulting larger apparent rate constants. observed photocatalysis enhancement accounts unique band structure an extremely small gap exclusive absorption visible region. This proof-of-concept work offers different perspective on help us better understand role involved photocatalysis, especially

Language: Английский

Citations

0