Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 129
Filter
1.
J Comp Eff Res ; 13(6): e240027, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38785682

ABSTRACT

Aim: To describe the epidemiological, clinical and laboratory characteristics and clinical progress of patients hospitalized with heart failure (HF) who started treatment with empagliflozin before discharge. Methods: We performed a retrospective observational study of patients aged ≥18 years admitted to the Internal Medicine Department of University Hospital Jaen, Jaen, Spain with acute HF between 1 May 2022 and 31 May 2023. Patients had to have a life expectancy of ≥1 year and have started treatment with empagliflozin during admission. Results: We included 112 patients (mean age, 85.2 ± 6.5 years; 67.9% women; 35.7 and 31.3% in NYHA functional classes III and IV; 73.2% with HF and preserved ejection fraction). Before admission, 80.4% were taking loop diuretics, 70.6% renin-angiotensin-aldosterone system inhibitors, 49.1% betablockers and 25% mineralocorticoid receptor antagonists. At admission, 94.6% were taking furosemide (15.2% at high doses, 36.6% at intermediate doses). The dose of furosemide was reduced at initiation of empagliflozin. At the end of follow-up, 13.4% of patients had died, 93.8% of the survivors continued treatment with empagliflozin and 26.8% had attended the emergency department with signs and symptoms of HF. Conclusion: Introduction of empagliflozin before discharge from hospital in patients admitted with HF made it possible to reduce the dose of diuretics during admission. The frequency of complications was as expected, and treatment was largely maintained.


Subject(s)
Benzhydryl Compounds , Glucosides , Heart Failure , Hospitalization , Sodium-Glucose Transporter 2 Inhibitors , Humans , Glucosides/therapeutic use , Female , Heart Failure/drug therapy , Male , Benzhydryl Compounds/therapeutic use , Retrospective Studies , Aged , Aged, 80 and over , Sodium-Glucose Transporter 2 Inhibitors/therapeutic use , Spain , Hospitalization/statistics & numerical data , Acute Disease
2.
Chemistry ; 30(29): e202304291, 2024 May 23.
Article in English | MEDLINE | ID: mdl-38490950

ABSTRACT

The reaction between bis(1,2,3-triazol-1-yl)methane derivatives and nBuLi and various aldehydes, yielded novel neutral ligand precursors incorporating alcohol functional groups. The resulting compounds exhibited distinct characteristics depending on the steric hindrance of the aldehyde employed. In instances where aromatic aldehydes were utilized, functionalization occurred at the methine group bridging both triazole rings. Conversely, the use of pivalic aldehyde prompted functionalization at the C5 position of the triazole ring. These compounds were subsequently employed as ligand precursors in the synthesis of organometallic aluminum and zinc complexes, yielding dinuclear complexes with high efficiency. The structural elucidation of all compounds was accomplished through spectroscopic methods and validated by X-ray crystallography. Preliminary catalytic investigations into the coupling reaction of cyclohexene oxide and CO2 revealed that aluminum and zinc complexes catalyzed the selective formation of polyether and polycarbonate materials, respectively.

3.
J Inorg Biochem ; 253: 112486, 2024 04.
Article in English | MEDLINE | ID: mdl-38266323

ABSTRACT

The modular synthesis of the heteroscorpionate core is explored as a tool for the rapid development of ruthenium-based therapeutic agents. Starting with a series of structurally diverse alcohol-NN ligands, a family of heteroscorpionate-based ruthenium derivatives was synthesized, characterized, and evaluated as an alternative to platinum therapy for breast cancer therapy. In vitro, the antitumoral activity of the novel derivatives was assessed in a series of breast cancer cell lines using UNICAM-1 and cisplatin as metallodrug control. Through this approach, a bimetallic heteroscorpionate-based metallodrug (RUSCO-2) was identified as the lead compound of the series with an IC50 value range as low as 3-5 µM. Notably, RUSCO-2 was found to be highly cytotoxic in TNBC cell lines, suggesting a mode of action independent of the receptor status of the cells. As a proof of concept and taking advantage of the luminescent properties of one of the complexes obtained, uptake was monitored in human breast cancer MCF7 cell lines by fluorescence lifetime imaging microscopy (FLIM) to reveal that the compound is evenly distributed in the cytoplasm and that the incorporation of the heteroscorpionate ligand protects it from aqueous processes, conversion in another entity, or the loss of the chloride group. Finally, ROS studies were conducted, lipophilicity was estimated, the chloride/water exchange was studied, and stability studies in simulated biological media were carried out to propose structure-activity relationships.


Subject(s)
Antineoplastic Agents , Breast Neoplasms , Coordination Complexes , Ruthenium , Humans , Female , Breast Neoplasms/drug therapy , Ruthenium/pharmacology , Ruthenium/therapeutic use , Ligands , Chlorides , MCF-7 Cells , Cell Line, Tumor
4.
Inorg Chem ; 62(37): 14833-14837, 2023 Sep 18.
Article in English | MEDLINE | ID: mdl-37676111

ABSTRACT

The successful architecture of active catalytic species with enhanced efficiencies is critical for the optimal exploitation of sustainable resources in industrially demanded processes. In this work, we describe the preparation of novel helical heterobimetallic Al/Mg-based complexes of the type [AlMe2(pbpamd-)MgR{κ1-O-(OC4H8O)}] [R = Et (1a), tBu (2a)] as potential catalysts. The design was performed through the sequential addition of the Al fragment to the ligand, followed by the Mg platform, resulting in a planar π-C2N2(sp2)-Al/Mg bridging core between metals. The new heterobimetallic species have been unambiguously characterized by single-crystal X-ray analysis. NOESY, DOSY, and EXSY NMR studies as well as density functional theory calculations corroborate both a rearrangement in solution to scorpionate complexes containing an unprecedented apical carbanion with a direct σ-C(sp3)-Al covalent bond named [{Mg(R)(pbpamd-) Al(Me)2}] [R = Et (1b), tBu (2b)] and an interconversion equilibrium between both isomers. We verified their utility and high efficiency as catalysts in the well-controlled ring-opening polymerization of the biorenewable l- and rac-lactide (LA) at 23 °C, reaching a remarkable turnover frequency value close to 25000 h-1 for rac-LA at this temperature and exerting a significant level of heteroselectivity (Pr = 0.80). Very interestingly, the kinetics demonstrate apparent first-order with respect to the catalyst and LA, which supports a synergic intramolecular cooperation between centers with electronic modulation among them.

5.
Front Cell Infect Microbiol ; 13: 1100947, 2023.
Article in English | MEDLINE | ID: mdl-37051297

ABSTRACT

Staphylococcus aureus is one of the species with the greatest clinical importance and greatest impact on public health. In fact, methicillin-resistant S. aureus (MRSA) is considered a pandemic pathogen, being essential to develop effective medicines and combat its rapid spread. This study aimed to foster the translation of clinical research outcomes based on metallodrugs into clinical practice for the treatment of MRSA. Bearing in mind the promising anti-Gram-positive effect of the heteroscorpionate ligand 1,1'-(2-(4-isopropylphenyl)ethane-1,1-diyl)bis(3,5-dimethyl-1H-pyrazole) (2P), we propose the coordination of this compound to platinum as a clinical strategy with the ultimate aim of overcoming resistance in the treatment of MRSA. Therefore, the novel metallodrug 2P-Pt were synthetized, fully characterized and its antibacterial effect against the planktonic and biofilm state of S. aureus evaluated. In this sense, three different strains of S. aureus were studied, one collection strain of S. aureus sensitive to methicillin and two clinical MRSA strains. To appraise the antibacterial activity, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) were determined. Moreover, successful outcomes on the development of biofilm in a wound-like medium were obtained. The mechanism of action for 2P-Pt was proposed by measuring the MIC and MBC with EDTA (cation mediated mechanism) and DMSO (exogenous oxidative stress mechanism). Moreover, to shed light on the plausible antistaphylococcal mechanism of this novel platinum agent, additional experiments using transmission electron microscopy were carried out. 2P-Pt inhibited the growth and eradicated the three strains evaluated in the planktonic state. Another point worth stressing is the inhibition in the growth of MRSA biofilm even in a wounded medium. The results of this work support this novel agent as a promising therapeutic alternative for preventing infections caused by MRSA.


Subject(s)
Methicillin-Resistant Staphylococcus aureus , Staphylococcus aureus , Platinum/pharmacology , Anti-Bacterial Agents/pharmacology , Methicillin/pharmacology , Microbial Sensitivity Tests , Biofilms
6.
Dalton Trans ; 52(18): 6105-6116, 2023 May 09.
Article in English | MEDLINE | ID: mdl-37066987

ABSTRACT

The fixation of CO2 mediated by metal-based catalysts for the production of organic molecules of industrial interest such as cyclic carbonates is urgently required under green and eco-friendly conditions. Herein, we describe the easy preparation of sterically demanding scorpionate ligands bearing different electron-withdrawing groups, and their coordination ability for the preparation of robust zinc-based mononuclear complexes of the type [ZnMe(κ3-NNN')] (4-6). These complexes, in combination with co-catalysts comprising larger ionic radius-based halides such as tetra-n-butylammonium, functioned as very active and selective catalysts for CO2 fixation into five-membered cyclic carbonates. These studies have led to the development of sustainable, inexpensive, and low-toxicity systems formed by 4-5 and Bu4NBr for the cycloaddition of CO2 into epoxides under very mild and solvent-free conditions, reaching very good to excellent conversions (TOF = 260 h-1). Moreover, these bicomponent systems show a broad substrate scope and functional group tolerance, including mono- and di-substituted epoxides, as well as bio-renewable diepoxides. Very interestingly, these are the first zinc-based systems reported to date for the successful transformation of the very challenging tri-substituted terpene-derived cis/trans-limonene oxide, whose reaction proceeds with high stereoselectivity to the formation of the bicyclic trans-limonene carbonate. Additionally, these bicomponents can be efficiently used up to six times without significant loss of activity. Kinetic investigations confirmed that the reaction shows an apparent first-order dependence on the catalyst and co-catalyst concentrations, which indicates an intramolecular monometallic mechanism.

7.
Dalton Trans ; 52(11): 3482-3492, 2023 Mar 14.
Article in English | MEDLINE | ID: mdl-36843480

ABSTRACT

Ring-opening copolymerization reactions of epoxides, carbon dioxide and cyclic esters to produce copolymers is a promising strategy to prepare CO2-based polymeric materials. In this contribution, bimetallic chloride indium complexes have been developed as catalysts for the copolymerization processes of cyclohexene oxide, carbon dioxide and L-lactide under mild reaction conditions. The catalysts displayed good catalytic activity and excellent selectivity towards the preparation of poly(cyclohexene carbonate) (PCHC) at one bar CO2 pressure in the absence of a co-catalyst. Additionally, polyester-polycarbonate copolymers poly(lactide-co-cyclohexene carbonate) (PLA-co-PCHC) were obtained via an one-pot one-step route without the use of a co-catalyst. The degree of incorporation of carbon dioxide can be easily modulated by changing the CO2 pressure and the monomer feed, resulting in copolymers with different thermal properties.

8.
J Mater Chem B ; 11(2): 316-324, 2023 01 04.
Article in English | MEDLINE | ID: mdl-36353924

ABSTRACT

Population growth, depletion of world resources and persistent toxic chemical production underline the need to seek new smart materials from inexpensive, biodegradable, and renewable feedstocks. Hence, "metal-free" ring-opening copolymerization to convert biomass carvone-based monomers into non-conventional luminescent biopolymers is considered a sustainable approach to achieve these goals. The non-conventional emission was studied in terms of steady-state and time-resolved spectroscopy in order to unravel the structure-properties for different carvone-based copolymers. The results highlighted the importance of the final copolymer folding structure as well as its environment in luminescent behavior (cluster-triggered emission). In all cases, their luminescent behavior is sensitive to small temperature fluctuations (where the minimum detected temperature is Tm ∼ 2 °C and relative sensitivity is Sr ∼ 6% °C) even at the microscopic scale, which endows these materials a great potential as thermosensitive smart polymers for photothermal imaging.


Subject(s)
Luminescence , Polymers , Polymers/chemistry , Biomass , Cyclohexane Monoterpenes
9.
Materials (Basel) ; 15(23)2022 Dec 06.
Article in English | MEDLINE | ID: mdl-36500193

ABSTRACT

Compaction is a common ground improvement technique based on the densification of soils for an energy level and optimum water content, mainly influenced by the particle size and curve gradation. Poorly compactable sands, characterized as cohesionless, fine and uniformly graded, are a challenge for earthworks since compaction is not effective due to the lack of a larger range of particle sizes to infill the voids and the compaction energy is not relevant either. These characteristics are common to other materials, i.e., desert sand, industrial or mining by-products or quarry fines, which are mostly discarded to landfill and replaced by proper soils, causing serious environmental issues. To enlarge the technical feasibilities of poorly compactable sands, reducing construction waste and raw material consumption, a mechanical stabilization, based on a repetitive series of recycling and recompaction without binder, is experimentally explored. The behavior observed is also analyzed from reported correlations and a packing particle approach, attending to densification stage, saturation degree, recompaction series, coordination number and packing density. The improvement achieved is moderate and dependent on the cycles applied, showing a characteristic repetitive pattern in the compaction curve, and approaching the estimated minimum void ratio and the theoretical maximum packing possibilities without degradation of the material.

10.
Cancers (Basel) ; 14(18)2022 Sep 15.
Article in English | MEDLINE | ID: mdl-36139634

ABSTRACT

BRCA1/2 protein-deficient or mutated cancers comprise a group of aggressive malignancies. Although PARPis have shown considerably efficacy in their treatment, the widespread use of these agents in clinical practice is restricted by various factors, including the development of acquired resistance due to the presence of compensatory pathways. BETis can completely disrupt the HR pathway by repressing the expression of BRCA1 and could be aimed at generation combination regimes to overcome PARPi resistance and enhance PARPi efficacy. Due to the poor pharmacokinetic profile and short half-life, the first-in-class BETi JQ1 was loaded into newly developed nanocarrier formulations to improve the effectivity of olaparib for the treatment of BRCAness cancers. First, polylactide polymeric nanoparticles were generated by double emulsion. Moreover, liposomes were prepared by ethanol injection and evaporation solvent method. JQ1-loaded drug delivery systems display optimal hydrodynamic radii between 60 and 120 nm, with a very low polydispersity index (PdI), and encapsulation efficiencies of 92 and 16% for lipid- and polymeric-based formulations, respectively. Formulations show high stability and sustained release. We confirmed that all assayed JQ1 formulations improved antiproliferative activity compared to the free JQ1 in models of ovarian and breast cancers. In addition, synergistic interaction between JQ1 and JQ1-loaded nanocarriers and olaparib evidenced the ability of encapsulated JQ1 to enhance antitumoral activity of PARPis.

11.
Polymers (Basel) ; 14(13)2022 Jul 02.
Article in English | MEDLINE | ID: mdl-35808764

ABSTRACT

Nonisocyanate polyurethane materials with pending alcohol groups in the polymeric chain were synthesized by polyaddition reaction of bis(cyclic carbonates) onto diamines. For the platform molecule, 1,4-butanediol bis(glycidyl ether carbonate) (BGBC, 1) was used. The polyaddition reaction of 1 onto a wide range of diamines with different electronic and physical properties was explored. All PHUs were obtained quantitatively after 16 h at 80 °C temperature in MeCN as solvent. The low nucleophilicity of L-lysine has proven unable to ring-open the cyclic carbonate and, thus, no reaction occurred. The addition of DBU or TBD as the catalyst was tested and allows the obtention of the desired PHU. However, the presence of strong bases also led to the formation of polyurea fragments in the new PHU. The different poly(hydroxyurethane) materials were characterized using a wide range of spectroscopic techniques such as NMR, IR, MALDI-ToF, and using GPC studies. The thermal properties of the NIPUs were investigated by DSC and TGA analyses. Moreover, reactions employing different monomer ratios were performed, obtaining novel hydroxycarbamate compounds. Finally, sequential and one-pot experiments were also carried out to synthesize the PHUs polymers in one-step reaction.

12.
Dalton Trans ; 51(30): 11302-11315, 2022 Aug 02.
Article in English | MEDLINE | ID: mdl-35822413

ABSTRACT

Novel polynuclear helical aluminium complexes supported by bulky heteroscorpionate ligands have been developed and characterised. The use of bulkier ligands has allowed the isolation of unprecedented intermediates for the preparation of helical aluminium complexes. The catalytic activity of these aluminium complexes for cyclic carbonates formation has also been investigated under mild reaction conditions. The combination of complex 16 and Bu4NBr catalysed the synthesis of a broad range of monosubstituted cyclic carbonates from their corresponding epoxides and CO2 at 25 °C and one bar of CO2 pressure. This catalyst system also showed good catalytic activity for the preparation of disubstituted cyclic carbonates from internal epoxides and CO2.

13.
Nutrients ; 14(9)2022 Apr 28.
Article in English | MEDLINE | ID: mdl-35565818

ABSTRACT

Background: Phase Angle (PhA) value measured by bioelectrical impedance analysis (BIA) could be considered a good marker of the patient's cell mass and cellular damage. Various studies have shown that the value of PhA is associated with an increased nutritional risk in several pathologies. However, not many studies have focused on the use of PhA as a screening tool in admitted patients. The aim of this study is to evaluate the prognostic value of PhA to determine disease-related malnutrition (DRM) and the risk that this entails for mortality and length of stay (LOS). Methods: 570 patients admitted to the hospital for different causes were included in this retrospective observational study. Patients' nutritional risk was assessed by screening tests such as the Malnutrition Universal Screening tool (MUST) and Subjective Global Assessment (SGA), in addition to non-invasive functional techniques, such as BIA and handgrip strength (HGS), 24−48 h after admission. After performing an SGA as the gold standard to assess malnutrition, PhA and SPhA values were used to determine DRM. Furthermore, both samples: malnutrition status (MS) and non-malnutrition status (NMS) were compared, with SphA-Malnutrition corresponding to a diagnosis of malnutrition. Statistical analysis of the sample was conducted with JAMOVI version 2.2.2. Results: Patients with MS had lower PhA and SPhA than patients with NMS (p < 0.001). The ROC curve analysis (AUC = 0.81) showed a cut-off point for MS for PhA = 5.4° (sensitivity 77.51% and specificity 74.07%) and AUC = 0.776 with a cut-off point for SPhA = −0.3 (sensitivity 81.74% and specificity 63.53%). Handgrip strength (HGS) was also observed to be a good predictor in hospitalized patients. Carrying out a comparative analysis between MS and NMS, length of stay (LOS) was 9.0 days in MS vs. 5.0 days in NMS patients (OR 1.07 (1.04−1.09, p < 0.001)). A low SPhA-malnutrition value (SPhA < −0.3) was significantly associated with a higher mortality hazards ratio (HR 7.87, 95% CI 2.56−24.24, p < 0.001). Conclusion: PhA, SPhA and HGS are shown to be good prognostic markers of DRM, LOS and mortality and could therefore be useful screening tools to complement the nutritional assessment of admitted patients.


Subject(s)
Hand Strength , Malnutrition , Electric Impedance , Hospitalization , Humans , Malnutrition/diagnosis , Nutrition Assessment , Nutritional Status
14.
Polymers (Basel) ; 14(2)2022 Jan 07.
Article in English | MEDLINE | ID: mdl-35054639

ABSTRACT

Stereo-diblock copolymers of high molecular weight polylactide (PLA) were synthetized by the one pot-sequential addition method assisted by a heteroscorpionate catalyst without the need of a co-initiator. The alkyl zinc organometallic heteroscorpionate derivative (Zn(Et)(κ3-bpzteH)] (bpzteH = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide) proved to assist in the mechanism of reaction following a coordination-insertion process. Kinetic studies along with the linear correlation between monomer and number average molecular weight (Mn) conversion, and the narrow polydispersities supported the truly living polymerization character of the initiator, whereas matrix-assisted laser desorption/Ionization-time of flight (MALDI-TOF) studies showed a very low order of transesterification. The high stereo-control attained for the afforded high molecular weight derivatives was revealed by homonuclear decoupled 1H NMR spectra and polarimetry measurements. The nanostructure of the PLA derivatives was studied by both wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) and the stereocomplex phase of the PLA stereo-diblock copolymers was successfully identified.

15.
Pharmaceutics ; 13(10)2021 Sep 26.
Article in English | MEDLINE | ID: mdl-34683852

ABSTRACT

Despite some limitations such as long-term side effects or the potential presence of intrinsic or acquired resistance, platinum compounds are key therapeutic components for the treatment of several solid tumors. To overcome these limitations, maintaining the same efficacy, organometallic ruthenium(II) compounds have been proposed as a viable alternative to platinum agents as they have a more favorable toxicity profile and represent an ideal template for both, high-throughput and rational drug design. To support the preclinical development of bis-phoshino-amine ruthenium compounds in the treatment of breast cancer, we carried out chemical modifications in the structure of these derivatives with the aim of designing less toxic and more efficient therapeutic agents. We report new bis-phoshino-amine ligands and the synthesis of their ruthenium counterparts. The novel ligands and compounds were fully characterized, water stability analyzed, and their in vitro cytotoxicity against a panel of tumor cell lines representative of different breast cancer subtypes was evaluated. The mechanism of action of the lead compound of the series was explored. In vivo toxicity was also assessed. The results obtained in this article might pave the way for the clinical development of these compounds in breast cancer therapy.

16.
Medicine (Baltimore) ; 100(29): e26533, 2021 Jul 23.
Article in English | MEDLINE | ID: mdl-34398008

ABSTRACT

ABSTRACT: The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2, keeps spreading globally. Evidence suggests that a subgroup of patients with severe symptomatology might have cytokine storms, which increases mortality. The use of interleukin-6 (IL-6) inhibitors may help in controlling the pathological immune response to the virus. Tocilizumab, a monoclonal antibody against IL-6, stands as an optional treatment for COVID-19 patients presenting this inflammatory hyper-response.We conducted a retrospective, observational, cohort study including 50 patients affected by COVID-19 with severe pneumonia and poor prognosis criteria, who have also undergone standard treatment; 36 of these patients additionally received tocilizumab in an early stage. The need for intensive care unit (ICU) admission, mortality, recovery of respiratory function, and improvement of biochemical and hematological parameters were compared between cohorts.Most patients were men, non-smokers and the most frequently reported comorbidities were hypertension and diabetes. Recurrent symptoms were fever, cough, and dyspnoea. 54.8% of patients from the tocilizumab group needed intubation, while in the control group 85.7% needed it. Treatment with tocilizumab significatively increased IL-6 levels, (554.45; CI 95% 186.69, 1032.93; P < .05) while C-reactive protein mean levels were reduced (-108.19; CI 95% -140.15, -75.33; P < .05), but no significant difference was found between cohorts. In comparison with the controls, tocilizumab reduced mortality (25.0% vs 42.9%, P = .021) and the number of ICU admissions (63.9% vs 100.0%, P = .021). 44.1% of patients treated with tocilizumab showed favorable radiological evolution, when compared with 15.4% of patients from the control group.Tocilizumab may improve clinical symptoms and mitigate deterioration observed in severe COVID-19 patients, and could be considered as an effective therapeutic option in subjects experiencing a significant inflammatory response to the disease.


Subject(s)
Antibodies, Monoclonal, Humanized/therapeutic use , COVID-19 Drug Treatment , Intensive Care Units/statistics & numerical data , Interleukin-6/antagonists & inhibitors , Pneumonia, Viral/drug therapy , Adult , Aged , Aged, 80 and over , COVID-19/complications , COVID-19/diagnosis , COVID-19/mortality , Female , Humans , Male , Middle Aged , Pneumonia, Viral/diagnosis , Pneumonia, Viral/etiology , Pneumonia, Viral/mortality , Prognosis , Retrospective Studies
17.
Polymers (Basel) ; 13(14)2021 Jul 19.
Article in English | MEDLINE | ID: mdl-34301114

ABSTRACT

The direct reaction of the highly sterically demanding acetamidinate-based NNN'-scorpionate protioligand Hphbptamd [Hphbptamd = N,N'-di-p-tolylbis(3,5-di-tertbutylpyrazole-1-yl)acetamidine] with one equiv. of ZnMe2 proceeds in high yield to the mononuclear alkyl zinc complex [ZnMe(κ3-phbptamd)] (1). Alternatively, the treatment of the corresponding lithium precursor [Li(phbptamd)(THF)] with ZnCl2 yielded the halide complex [ZnCl(κ3-phbptamd)] (2). The X-ray crystal structure of 1 confirmed unambiguously a mononuclear entity in these complexes, with the zinc centre arranged with a pseudotetrahedral environment and the scorpionate ligand in a κ3-coordination mode. Interestingly, the inexpensive, low-toxic and easily prepared complexes 1 and 2 resulted in highly efficient catalysts for the ring-opening polymerisation of lactides, a sustainable bio-resourced process industrially demanded. Thus, complex 1 behaved as a single-component robust initiator for the living and immortal ROP of rac-lactide under very mild conditions after a few hours, reaching a TOF value up to 5520 h-1 under bulk conditions. Preliminary kinetic studies revealed apparent zero-order dependence on monomer concentration in the absence of a cocatalyst. The PLA materials produced exhibited narrow dispersity values, good agreement between the experimental Mn values and monomer/benzyl alcohol ratios, as well as enhanced levels of heteroselectivity, reaching Ps values up to 0.74.

18.
Polymers (Basel) ; 13(10)2021 May 19.
Article in English | MEDLINE | ID: mdl-34069623

ABSTRACT

The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO2 as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts tested for the ROCOP of CHO and phthalic anhydride at different reaction conditions, the most active catalytic system was the combination of complex 3 with bis(triphenylphosphine)iminium as cocatalyst in toluene at 80 °C. Once the optimal catalytic system was determined, the scope in terms of other cyclic anhydrides was broadened. The catalytic system was capable of copolymerizing selectively and efficiently CHO with phthalic, maleic, succinic and naphthalic anhydrides to afford the corresponding polyester materials. The polyesters obtained were characterized by spectroscopic, spectrometric, and calorimetric techniques. Finally, the reaction mechanism of the catalytic system was proposed based on stoichiometric reactions.

19.
ChemSusChem ; 14(9): 2084-2092, 2021 May 06.
Article in English | MEDLINE | ID: mdl-33666346

ABSTRACT

Fast addition of highly polar organometallic reagents (RMgX/RLi) to cyclic carbonates (derived from CO2 as a sustainable C1 synthon) has been studied in 2-methyltetrahydrofuran as a green reaction medium or in the absence of external volatile organic solvents, at room temperature, and in the presence of air/moisture. These reaction conditions are generally forbidden with these highly reactive main-group organometallic compounds. The correct stoichiometry and nature of the polar organometallic alkylating or arylating reagent allows straightforward synthesis of: highly substituted tertiary alcohols, ß-hydroxy esters, or symmetric ketones, working always under air and at room temperature. Finally, an unprecedented one-pot/two-step hybrid protocol is developed through combination of an Al-catalyzed cycloaddition of CO2 and propylene oxide with the concomitant fast addition of RLi reagents to the in situ and transiently formed cyclic carbonate, thus allowing indirect conversion of CO2 into the desired highly substituted tertiary alcohols without need for isolation or purification of any reaction intermediates.

20.
Chempluschem ; 86(3): 460-468, 2021 03.
Article in English | MEDLINE | ID: mdl-33704907

ABSTRACT

Bio-derived furan- and diacid-derived cyclic carbonates have been synthesized in high yields from terminal epoxides and CO2 . Furthermore, four highly substituted terpene-derived cyclic carbonates were isolated in good yields with excellent diastereoselectivity in some cases. Eleven new cyclic carbonates derived from 10-undecenoic acid under mild reaction conditions were prepared, providing the corresponding carbonate products in excellent yields. The catalyst system also performed the conversion of an epoxidized fatty acid n-pentyl ester into a cyclic carbonate under relatively mild reaction conditions (80 °C, 20 bar, 24 h). This bis(cyclic carbonate) was obtained in high yields and with different cis/trans ratios depending on the co-catalyst used. An allyl alcohol by-product was only observed as a minor product when bis(triphenylphosphine)iminium chloride was used as co-catalyst. Finally, two cyclic carbonates were used as building blocks for the preparation of non-isocyanate poly(hydroxy)urethanes by reaction with 1,4-diaminobutane.

SELECTION OF CITATIONS
SEARCH DETAIL
...