Next Article in Journal
Natural Cyclopeptide RA-XII, a New Autophagy Inhibitor, Suppresses Protective Autophagy for Enhancing Apoptosis through AMPK/mTOR/P70S6K Pathways in HepG2 Cells
Previous Article in Journal
NeoBOMB1, a GRPR-Antagonist for Breast Cancer Theragnostics: First Results of a Preclinical Study with [67Ga]NeoBOMB1 in T-47D Cells and Tumor-Bearing Mice
Article Menu
Issue 11 (November) cover image

Export Article

Open AccessArticle
Molecules 2017, 22(11), 1949;

Elucidating Direct Photolysis Mechanisms of Different Dissociation Species of Norfloxacin in Water and Mg2+ Effects by Quantum Chemical Calculations

Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
Authors to whom correspondence should be addressed.
Received: 1 November 2017 / Revised: 3 November 2017 / Accepted: 8 November 2017 / Published: 11 November 2017
(This article belongs to the Section Theoretical Chemistry)
Full-Text   |   PDF [2324 KB, uploaded 11 November 2017]   |  


The study of pollution due to combined antibiotics and metals is urgently needed. Photochemical processes are an important transformation pathway for antibiotics in the environment. The mechanisms underlying the effects of metal-ion complexation on the aquatic photochemical transformation of antibiotics in different dissociation forms are crucial problems in science, and beg solutions. Herein, we investigated the mechanisms of direct photolysis of norfloxacin (NOR) in different dissociation forms in water and metal ion Mg2+ effects using quantum chemical calculations. Results show that different dissociation forms of NOR had different maximum electronic absorbance wavelengths (NOR2+ < NOR0 < NOR+) and showed different photolysis reactivity. Analysis of transition states (TS) and reaction activation energies (Ea) indicated NOR+ generally underwent loss of the piperazine ring (C10–N13 bond cleavage) and damage to piperazine ring (N13–C14 bond cleavage). For NOR2+, the main direct photolysis pathways were de-ethylation (N7–C8 bond cleavage) and decarboxylation (C2–C5 bond cleavage). Furthermore, the presence of Mg2+ changed the order of the wavelength at maximum electronic absorbance (NOR+-Mg2+ < NOR0-Mg2+ < NOR2+-Mg2+) and increased the intensities of absorbance peaks of all three dissociation species of NOR, implying that Mg2+ played an important role in the direct photolysis of NOR0, NOR+, and NOR2+. The calculated TS results indicated that the presence of Mg2+ increased Ea for most direct photolysis pathways of NOR, while it decreased Ea for some direct photolysis pathways such as the loss of the piperazine ring and the damage of the piperazine ring of NOR0 and the defluorination of NOR+. View Full-Text
Keywords: norfloxacin; direct photolysis pathways; DFT; ionic forms; Mg2+ norfloxacin; direct photolysis pathways; DFT; ionic forms; Mg2+

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Supplementary material


Share & Cite This Article

MDPI and ACS Style

Wang, S.; Wang, Z. Elucidating Direct Photolysis Mechanisms of Different Dissociation Species of Norfloxacin in Water and Mg2+ Effects by Quantum Chemical Calculations. Molecules 2017, 22, 1949.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top