Comparative study on removal of platinum cytostatic drugs at trace level by cysteine, diethylenetriamino functionalized Si-gels and polyethyleneimine functionalized sponge : Adsorption performance and mechanisms

Altres ajuts: acords transformatius de la UABTo efficiently remove trace Pt-based cytostatic drugs (Pt-CDs) from aqueous environments, a comparative investigation was conducted on the adsorption behavior of three commercial adsorbents including cysteine-functionalized silica gel (Si-Cys), 3-(diethylenetriamino) propyl-functionalized silica gel (Si-DETA) and open-celled cellulose MetalZorb® sponge (Sponge). The research on the adsorption of cisplatin and carboplatin encompasses investigations of pH dependence, adsorption kinetics, adsorption isotherms, and adsorption thermodynamics. The obtained results were compared with those of PtCl42− to better understand the adsorption mechanisms. The adsorption of cisplatin and carboplatin by Si-Cys was significantly better than Si-DETA and Sponge, which suggested that in chelation-dominated chemisorption, thiol groups provided high-affinity sites for Pt(II) complexation. Adsorption of the anion PtCl42− was more pH dependent and generally superior to that of cisplatin and carboplatin, benefiting from the contribution of ion association with protonated surfaces. The removal process of aqueous Pt(II) compounds occurred by the hydrolysis of complexes in solution and subsequent adsorption, and the specific adsorption process was explained by the synergistic action of ion association and chelation mechanisms. The rapid adsorption processes involving diffusion and chemisorption were well described by pseudo-second-order kinetic model. The isotherm studies suggested monolayer adsorption, consistent with the Langmuir model. Indicated from the adsorption enthalpy results, the chelation of cisplatin and carboplatin with thiol groups was an endothermic reaction, while the adsorption of PtCl42− was exothermic. At 343 K, Si-Cys achieved 98.5 ± 0.1 % (cisplatin) and 94.1 ± 0.1 % (carboplatin) removal. To validate the obtained findings, the described process was applied to urine samples doped with Pt-CDs as analog of hospital wastewaters and the removal was very efficient, ranging from 72 ± 1 % to 95 ± 1 %, when using Si-Cys as adsorbent, although limited matrix effects were observed

Effect of the Heteroaromatic Antenna on the Binding of Chiral Eu(III) Complexes to Bovine Serum Albumin

The cationic enantiopure R) and luminescent Eu(III) complex [Eu(bisoQcd)(H2O)(2)] OTf (with bisoQcd = N,N'-bis(2-isaquinolinmethyl)-trarts-1,2diaminocyclohexane N/N1 -diacetate and OTf = triflate) was synthesized and characterized. At physiological pH, the 1:1 [Eu(bisoQcd)(H2O)(2)](+) species, possessing two water molecules in the inner coordination sphere, is largely dominant. The interaction with bovine serum albumin (BSA) was studied by means of several experimental techniques, such as luminescence spectroscopy, isothermal titration calorimeti-y (ITC), molecular docking (MD), and molecular dynamics simulations M11.-.)S). In this direction, a ligand competition study was also performed by using three clinically established drugs (i.e., ibuprofen, warfarin, and digito)cin). The nature of this interaction is strongly affected by the type of the involved heteroaromatic antenna in the complexes. In fact, the presence of isoqiiinolirie rings drives the corresponding complex toward the protein superficial area containing the tryptophan residue 134 (Trp134). As the main consequence, the metal center undergoes the loss of one water molecule upon interaction with the side chain of a glutamic acid residue. On the other hand, the similar complex containing pyridine rings f[Eti(bpcd)(H2O)(2)]Cl with bpcd = N,N'-bis(2-pytidylmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate)interacts more weakly with the protein in a different superficial cavity, without losing the coordinated water molecules

Dynamics of the Energy Transfer Process in Eu(III) Complexes Containing Polydentate Ligands Based on Pyridine, Quinoline, and Isoquinoline as Chromophoric Antennae

In this work, we investigated from a theoretical point of view the dynamics of the energy transfer process from the ligand to Eu(III) ion for 12 isomeric species originating from six different complexes differing by nature of the ligand and the total charge. The cationic complexes present the general formula [Eu(L)(H2O)2]+ (where L = bpcd2- = N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate; bQcd2- = N,N'-bis(2-quinolinmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate; and bisoQcd2- = N,N'-bis(2-isoquinolinmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate), while the neutral complexes present the Eu(L)(H2O)2 formula (where L = PyC3A3- = N-picolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetate; QC3A3- = N-quinolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetate; and isoQC3A3- = N-isoquinolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetate). Time-dependent density functional theory (TD-DFT) calculations provided the energy of the ligand excited donor states, distances between donor and acceptor orbitals involved in the energy transfer mechanism (RL), spin-orbit coupling matrix elements, and excited-state reorganization energies. The intramolecular energy transfer (IET) rates for both singlet-triplet intersystem crossing and ligand-to-metal (and vice versa) involving a multitude of ligand and Eu(III) levels and the theoretical overall quantum yields (ϕovl) were calculated (the latter for the first time without the introduction of experimental parameters). This was achieved using a blend of DFT, Judd-Ofelt theory, IET theory, and rate equation modeling. Thanks to this study, for each isomeric species, the most efficient IET process feeding the Eu(III) excited state, its related physical mechanism (exchange interaction), and the reasons for a better or worse overall energy transfer efficiency (ηsens) in the different complexes were determined. The spectroscopically measured ϕovl values are in good agreement with the ones obtained theoretically in this work

Cobalt extraction from Chloride/Nitrate/Sulfate Media with Phosphonium-based Ionic Liquids.

Room temperature ionic liquids (RTILs) have emerged and attracted increasing interest in the past few years in numerous applications. RTILs are salts generally composed by an organic cation and an inorganic anion in the liquid state at 25 °C. They present high thermal and chemical stability, non-flammability, wide electrochemical window, low volatility and low toxicity [1]. Moreover, these properties can be finely tuned by systematically altering the structure of cations and anions. Due to these attractive features, RTILs have been used as "green" substitutes of volatile organic solvents in a number of applications related to the energy and environmental fields (e.g. separations, extractions, electrochemistry and catalysis). Among these, the use of RTILs for the separation and recycling of “critical” metals deriving from mining or high-tech waste was proposed in the last decade [2]. The recycling of cobalt assumed a growing importance due to the growing demand related to his use in key technologies, such as Li-ion batteries or motors for electric mobility [3]. The current processes for cobalt recovery in the hydrometallurgical route from aqueous solutions have some advantages such as method flexibility, high purity and low energy consumption [4] and some works on the application of RTILs in such process have appeared in the last years [4,5]. Among the available RTILs, those based on phosphonium cation (Figure 1) have been studied for metal extractions in recent years [6]. However, only few works were focused on the nature of the dissolved metals and their speciation in RTILs [7], despite these are fundamental data to understand the separation processes. In this communication, the results on Co(II) extraction in chloride/nitrate/sulfate media using [P66614][Cl], [P66614][Decanoate] and [P66614][Br] are reported, along with the extraction efficiency. The interest in the Co2+ extraction with different media is due to the fact that the liquid samples containing the metal to be recovered usually can give extractions greater than 95%, with different Co(II) coordination. In addition, after stripping, the ionic liquid phase can be regenerated. References: [1] a) K. M. Docherty, C. F. Kulpa, Jr., Green Chem. 2005, 7 (4), 185-189; b) M. Armand, F. Endres, D. R. MacFarlane, H. Ohno, B. Scrosati, Nat. Mater. 2009, 8, 621-629. [2] a) A. P. Abbott, G. Frisch, J. Hartley, K. S. Ryder, Green Chem. 2011, 13 (3), 471-481; b) A.P. Paiva, C.A. Nogueira, Waste Biom.Valoriz. 2021, 12, 1725-1747. [3] J. Piatek, S. Afyon, T. M. Budnyak, S. Budnyk, M. H Sipponen, A. Slabon, Adv. Energy Mater. 2020, 11, 2003456. [4] E. A. Othman, A. G. J van der Ham, H. Miedema, S. R. A Kersten, Sep. Purif. Technol. 2020, 252, 117435. [5] L. Xu, C. Chen, M.-L. Fu, Hydrometallurgy 2020, 197, 105439. [6] K.J. Fraser, D. R. MacFarlane, Austr. J. Chem. 2009, 62 (4) 309-321. [7] M. Busato, A. Lapi, P. D’Angelo, A. Melchior, J. Phys. Chem. B 2021, 125 (24), 6639

Cobalt(II) complex formation in [C4mim][Tf2N]

Room temperature ionic liquids (RTILs) have been used as "green" substitutes of organic solvents in a number of applications, due to several advantages over the latter and numerous useful physicochemical properties [1] As far as the separation and recycling of “critical” metals is concerned, the use of hydrophobic RTILs as extracting phases in hydrometallurgical processes has been proposed in the last decade [2]. In particular, the recycling of cobalt assumed growing importance due to the increased demand related to his use in expanding markets, such as Li-ion batteries or electric motors [3]. Therefore the knowledge of speciation and structure of the Co(II) ion in RTILs can provide key information for developing efficient recylcing processes. Among the available RTILs, those based on the N,N’-alkylimidazolium (CnCmim+) cation and bis(trifluoromethylsulfonyl)imide (Tf2N-) anion have been extensively studied for metal extractions and electrochemical depositions. However, only few works[4]are focused on the nature of the dissolved metals and their speciation in RTILs. With the aim to fill this gap, in this communication, we report the results on Co(II) complex formation with nitrate and chloride anions in [C4mim][Tf2N] (C4mim = 1-methyl-3 butylimidazolium). The nature of the species formed in [C4mim][Tf2N] is determined experimentally by means of spectrophotometry and calorimetry. Density Functional Theory (DFT) and molecular dynamics (MD) calculations are employed to get information on the structure and solvation of the complexes. Our results show that stable CoXj (j = 1-4 and 1-3 for Cland NO3- , respectively) are formed. In the case of Cl- , a change of coordination (octahedral → tetrahedral) occurs (Figure 1) in the 1:2 species. MD simulations provided the Co(II) coordination number and information on the arrangement of the [Tf2N]- anions in solution. Also, it is observed that the second solvation shell, mostly composed by [C4mim]+ cations, contracts with the increase of the number of bound ligands (j). [1] Armand, M., Endres, F., MacFarlane, D. R. , Ohno, H., Scrosati, B. Nat. Mater. 2009, 8, 621-629. [2] Abbott, A. P., Frisch, G., Hartley, J., Ryder, K. S. Green Chem. 2011, 13 (3), 471-481. [3] Piatek., J. S. Afyon, T. M. Budnyak, S. Budnyk, M. H Sipponen, A. Slabon, Adv. Energy Mater. 2020, 2003456. [4] M. Busato, A. Lapi, P. D’Angelo, A. Melchior, J. Phys. Chem. B 2021, 125 (24), 6639

Thermodynamics of Co(II) Complexation with Nitrate and Chloride in the [C4mim][Tf2N] Ionic Liquid

Room temperature ionic liquids (RTILs) emerged as “green” solvents for numerous applications in the last two decades. RTILs are salts generally composed by an organic cation and an inorganic anion in the liquid state at 25 °C. They present high thermal and chemical stability, non-flammability, wide electrochemical window, low volatility and low toxicity [1]. Moreover, these properties can be finely tuned by systematically altering the structure of cations and anions. Due to these attractive features, RTILs have been used as "green" substitutes of volatile organic solvents in a number of applications related to the energy and environmental fields (e.g. separations, extractions, electrochemistry and catalysis). Among these, the use of RTILs for the separation and recycling of “critical” metals deriving from mining or high-tech waste was proposed in the last decade [2]. The recycling of cobalt assumed a great importance, due to the growing demand related to the use in key technologies, such as Li-ion batteries or motors for electric mobility [3]. The current processes for cobalt recovery in the hydrometallurgical route from aqueous solutions have some advantages such as method flexibility, high purity and low energy consumption [4] and some works on the application of RTILs in such process have appeared in the last years [4,5]. Among the available RTILs, those based on the alkylimidazolium (Cnmim+) cation and bis(trifluoromethylsulfonyl)imide (Tf2N-) anion have been studied for metal extractions in recent years [6]. However, only few works were focused on the nature of the dissolved metals and their speciation in RTILs [7], despite these are fundamental data to understand the separation processes. In this communication, the results on Co(II) complex formation with nitrate and chloride in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]) are reported. The interest in the Co2+ speciation with nitrate and chloride is due to the fact that the liquid samples containing the metal to be recovered usually contain high concentrations of these anions. The nature of the species formed in dry and water-saturated [C4mim][Tf2N] is determined by means of spectrophotometric, calorimetric and theoretical methods. The results evidence the great effect of water on the nature and stability of the species formed. References: [1] a) K. M. Docherty, C. F. Kulpa, Jr., Green Chem. 2005, 7 (4), 185-189; b) M. Armand, F. Endres, D. R. MacFarlane, H. Ohno, B. Scrosati, Nat. Mater. 2009, 8, 621-629. [2] a) A. P. Abbott , G. Frisch, J. Hartley, K. S. Ryder Green Chem. 2011, 13 (3), 471-481; b) A.P. Paiva, C.A. Nogueira, Waste Biom.Valoriz. 2021, 12, 1725-1747. [3] J. Piatek., S. Afyon, T. M. Budnyak, S. Budnyk, M. H Sipponen, A. Slabon, Adv. Energy Mater. 2020, 11, 2003456. [4] E. A. Othman, A. G. J van der Ham, H. Miedema, S. R. A Kersten, Sep. Purif. Technol. 2020, 252, 117435. [5] L. Xu, C. Chen, M.-L. Fu, Hydrometallurgy 2020, 197, 105439. [6] M. Gras, N. Papaiconomou, E. Chaînet, I. Billard, Solvent Extr. Ion Exch. 2018, 36 (6), 583-601. [7] M. Busato, A. Lapi, P. D’Angelo, A. Melchior, J. Phys. Chem. B 2021, 125 (24), 6639

Entropy and Enthalpy Effects on Metal Complex Formation in Non-Aqueous Solvents: The Case of Silver(I) and Monoamines

Access to the enthalpy and entropy of the formation of metal complexes in solution is essential for understanding the factors determining their thermodynamic stability and speciation. As a case study, in this report we systematically examine the complexation of silver(I) in acetonitrile (AN) with the following monoamines: n-propylamine (n-pr), n-butylamine (n-but), hexylamine (hexyl), diethylamine (di-et), dipropylamine (di-pr), dibutylamine (di-but), triethylamine (tri-et) and tripropylamine (tri-pr). The study shows that the complex stabilities are quite independent of the length of the substitution chain on the N atom and demonstrates that, in general, the overall enthalpy terms associated with the complex formation are strongly exothermic, whereas the entropy values oppose the complex formations. In addition, we examined the similarity of the formation constants of AgL complexes of the primary monoamines in AN, dimethylsulfoxide (DMSO) and water, which were unexpected on the basis of the difference between the donor properties of solvents

Adsorption of cisplatin by dithiocarbamate-functionalized silica.

Cytostatic drugs (CD), characterized by their environmental persistence have been detected in water bodies at concentrations up to μg/L levels.1 Several methods for the removal and degradation of CDs, have been developed,2 but they are relatively expensive and sometimes inefficient for CDs complete removal from the treated water. Among CDs, platinum-based chemotherapy agents are widely used for the treatment of a variety of cancers and demonstrate a high toxicity and low biodegradability. Such compounds, after administration, are excreted into hospital wastewater intact or as toxic metabolites in significant percentage.1 Effectively, Pt-based drugs have been detected in the mg/L range in hospital effluents and water treatment plants, raising concerns about the long-term exposure of living organisms to low levels of such compounds. A potentially efficient strategy to treat such low levels of Pt-containing contaminants is to selectively pre-concentrate the sample by adsorption, and then to further treat it e.g., by means of advanced oxidation processes. In this contribution, the adsorption of cisplatin by dithiocarbamate (DTC) modified silica is evaluated. The choice of this material is based on the high affinity of the thiocarbamate group for Pt2+, which, upon metal binding, causes the destruction of the original toxic compound. Also, the low-cost starting materials for the preparation of the adsorbent phase makes it attractive from an economic point of view. The functionalization of silica was carried out with a slightly modified literature procedure3 and characterized by IR, TGA and PZC analysis. Adsorption kinetics and isotherms have been built by analysing the free concentration of Pt by using UV-Vis spectrophotometry. The obtained material showed that equilibrium was reached after about 60 minutes of contact time with the cisplatincontaining solution. The mass/volume ratios between 1 and 10 mg/mL of adsorbent were tested. The adsorbent material retained up to 70% of the platinum present in the experimental conditions adopted. References [1] Roque-Diaz Y. et al. Processes, 2021, 11, 9, 1873 [2] Pieczyńska, A. et al. Crit. Rev. Env. Sci. Tech., 2017, 47, 1282 [3] Goubert-Renaudin, S. New J. Chem., 2009, 33, 528–53