Suspect screening of wastewaters to trace anti-COVID-19 drugs: Potential adverse effects on aquatic environment.

During the first period of the SARS-CoV-2 pandemic, the lack of specific therapeutic treatments led to the provisional use of a number of drugs, with a continuous review of health protocols when new scientific evidence emerged. The management of this emergency sanitary situation could not take care of the possible indirect adverse effects on the environment, such as the release of a large amount of pharmaceuticals from wastewater treatment plants. The massive use of drugs, which were never used so widely until then, implied new risks for the aquatic environment. In this study, a suspect screening approach using Liquid Chromatography-High Resolution Mass Spectrometry techniques, allowed us to survey the presence of pharmaceuticals used for COVID-19 treatment in three WWTPs of Lombardy region, where the first European cluster of SARS-CoV-2 cases was detected. Starting from a list of sixty-three suspect compounds used against COVID-19 (including some metabolites and transformation products), six compounds were fully identified and monitored together with other target analytes, mainly pharmaceuticals of common use. A monthly monitoring campaign was conducted in a WWTP from April to December 2020 and the temporal trends of some anti-COVID-19 drugs were positively correlated with those of COVID-19 cases and deaths. The comparison of the average emission loads among the three WWTPs evidenced that the highest loads of hydroxychloroquine, azithromycin and ciprofloxacin were measured in the WWTP which received the sewages from a hospital specializing in the treatment of COVID-19 patients. The monitoring of the receiving water bodies evidenced the presence of eight compounds of high ecological concern, whose risk was assessed in terms of toxicity and the possibility of inducing antibiotic and viral resistance. The results clearly showed that the enhanced, but not completely justified, use of ciprofloxacin and azithromycin represented a risk for antibiotic resistance in the aquatic ecosystems.

The role of the atomic charges on the ligands and platinum(II) in affecting the cis and trans influences in [PtXL(PPh3)2]+ complexes (X = NO3, Cl, Br, I; L = 4-substituted pyridines, amines, PPh3). A 31P NMR and DFT investigation.

One bond Pt-P coupling constants (1)J(PtP) of a series of cationic complexes [PtXL(PPh(3))(2)](+) (X = NO(3), Cl, Br, I; L = 4-Z-pyridines, Z = electron withdrawing or releasing groups, 4a-k; or X = Cl, L = NH(3), PhCH(2)NH(2) and (i)PrNH(2), 5a-c) have been used to establish the trans and cis influence sequences of X and pyridines. The crystal structure of compound 4f(BF(4)) with Z = (t)Bu has been resolved. In the pyridine complexes 4a-d (Z = H, variable X), both the trans and cis influence series of the anionic ligands X decrease along the same sequence I > Br > Cl > NO(3), as previously found for [PtX(PPh(3))(3)](+) (X = NO(3), Cl, Br, I, 3a-d), however in 4a-d the cis influence turns out to be more important than the trans. On the contrary, in [PtCl(4-Z-py)(PPh(3))(2)](+) (4b,e-k) the sequence of the trans influence of the 4-Z-pyridines is opposite to that of the cis, the latter being Z = CN > CHO > Br > PhCO > H > Me > (t)Bu > NH(2), i.e. the most basic pyridine gives rise to the lowest cis influence. This correlation was found to hold also for complexes 5a-c (L = amines). All the observed trends have been fully reproduced by B3LYP/def2-SVP DFT calculations, by looking at the relevant optimized bond lengths of selected complexes of type 3, 4 and 5. Subsequent evaluation of the atomic charges, by resorting to two independent methods, i.e., the Natural Bond Order analysis of the wavefunction and the Bader's Quantum Theory of Atoms in Molecules, allowed for rationalization of the origin of the cis and trans influences. The negative charge on the nitrogen atoms of free pyridines becomes more negative upon protonation and even more so when coordinated to the [PtCl(PPh(3))(2)](+) moiety. The least negatively charged nitrogen atom of coordinated pyridines is that of 4-CN-py (the highest cis influencing pyridine derivative), which gives rise to the lowest positive charge on Pt, confirming the relationship between the lowering of the charge on the metal ion and a high cis influence. The trans influence can be described in terms of competition between the charges on the two trans donor atoms. In contrast with the behaviour of pyridines, the positive charge on the phosphorous atom of free PPh(3) increases upon coordination to Pt(II), moreover the PPh(3) ligands acquire a substantial positive charge, thus efficiently delocalising the charge of the cationic complex.

Cis influence in trans-Pt(PPh3)2 complexes.

The cis influence of a series of anionic ligands X and Y has been evaluated through the magnitude of the Pt-P coupling constants for compounds of formula trans-[PtXY(PPh(3))(2)]. The order of decreasing cis influence was found to be I > Cl > SePh approximately SPh approximately SEt > NO(3) > AcO approximately NO(2) > H > Me > Ph > mtc (mtc = N,N-dimethylmonothiocarbamato-S); moreover, the cis influences of the various ligands was found to be additive. The X-ray structures of three representative compounds (t-: X = Cl, Y = NO(3); t-: X = Cl, Y = AcO and t-: X = Y = NO(2)) have also been determined.