TY - JOUR

T1 - Laser flash photolysis and quantum chemical studies of UV degradation of pharmaceutical drug chloramphenicol: Short-lived intermediates, quantum yields and mechanism of photolysis

AU - Belikov, Yury A.

AU - Snytnikova, Olga A.

AU - Sheven, Dmitriy G.

AU - Fedunov, Roman G.

AU - Grivin, Vyacheslav P.

AU - Pozdnyakov, Ivan P.

N1 - Yury A. Belikov, Roman G. Fedunov, Vyacheslav P. Grivin and Ivan P. Pozdnyakov (Voevodsky Institute of Chemical Kinetics and Combustion SB RAS ) acknowledge the core funding from the Ministry of Science and Higher Education of the Russian Federation ( FWGF-2021-0005 ). Authors also thank Center of Collective Use « Mass spectrometric investigations » SB RAS for the access to the LC/MS equipment.

PY - 2024/3

Y1 - 2024/3

N2 - Using methods of time-resolved and stationary photolysis, HPLC-MS and quantum-chemical calculations by the DFT method, the mechanism of direct UV photolysis of the antibiotic chloramphenicol (CAP) was established. For the first time, short-lived intermediates formed during photolysis were detected. The primary photoprocess is the cleavage of the β-C-C bond relative to the aromatic system with the formation of 4-nitrobenzylalcohol radical and residual aliphatic radical. The first radical in deoxygenated solutions predominantly transforms into para-nitrobenzaldehyde and its secondary photolysis products. In the presence of oxygen, the aromatic radical and para-nitrobenzaldehyde are transformed into para-nitrosobenzoic and para-nitrobenzoic acids as a result of reaction with reactive oxygen species (ROS). Formation of ROS is provoked by reactions of aliphatic radical with dissolved oxygen, so this radical is very important for CAP degradation. The quantum yield of direct photolysis of CAP is ∼3% and does not depend on the presence of dissolved oxygen and on the change of the excitation wavelength in the range of 254–308 nm. Obtained data are important for further understanding of the transformation pathways of CAP and similar PPCP in natural and wastewaters under the action of sunlight and artificial UV radiation.

AB - Using methods of time-resolved and stationary photolysis, HPLC-MS and quantum-chemical calculations by the DFT method, the mechanism of direct UV photolysis of the antibiotic chloramphenicol (CAP) was established. For the first time, short-lived intermediates formed during photolysis were detected. The primary photoprocess is the cleavage of the β-C-C bond relative to the aromatic system with the formation of 4-nitrobenzylalcohol radical and residual aliphatic radical. The first radical in deoxygenated solutions predominantly transforms into para-nitrobenzaldehyde and its secondary photolysis products. In the presence of oxygen, the aromatic radical and para-nitrobenzaldehyde are transformed into para-nitrosobenzoic and para-nitrobenzoic acids as a result of reaction with reactive oxygen species (ROS). Formation of ROS is provoked by reactions of aliphatic radical with dissolved oxygen, so this radical is very important for CAP degradation. The quantum yield of direct photolysis of CAP is ∼3% and does not depend on the presence of dissolved oxygen and on the change of the excitation wavelength in the range of 254–308 nm. Obtained data are important for further understanding of the transformation pathways of CAP and similar PPCP in natural and wastewaters under the action of sunlight and artificial UV radiation.

KW - Chloramphenicol

KW - Homolytic C–C bond cleavage

KW - Laser flash photolysis

KW - PPCP

KW - Photodegradation

KW - Quantum chemical calculations

KW - Short-lived intermediates

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85182745598&origin=inward&txGid=2b7103392990d326fbcf9e25a078b9c5

UR - https://www.mendeley.com/catalogue/1a898dd3-70b4-3a2b-848d-a491d942e04c/

U2 - 10.1016/j.chemosphere.2024.141211

DO - 10.1016/j.chemosphere.2024.141211

M3 - Article

C2 - 38219992

VL - 351

JO - Chemosphere

JF - Chemosphere

SN - 0045-6535

M1 - 141211

ER -