The synthesis of hybrid molecules is one of the current strategies of drug discovery for the development of new lead compounds. The 1,2,3-triazole moiety represents an important building block in Medicinal Chemistry, extensively present in recent years. In this paper, we presented the design and the synthesis of new 1,2,3-triazole hybrids, containing both an isatine and a phenolic core. Firstly, the non-commercial azide and the alkyne synthons were prepared by different isatines and phenolic acids, respectively. Then, the highly regioselective synthesis of 1,4-disubstituted triazoles was obtained in excellent yields by a click chemistry approach, catalyzed by Cu(I). Finally, a molecular docking study was performed on the hybrid library, finding four different therapeutic targets. Among them, the most promising results were obtained on 5-lipoxygenase, an enzyme involved in the inflammatory processes.

The zirconium complexes (OSSOCl)(ZrOBu2)-Bu-t (1), (OSSOBr)(ZrOBu2)-Bu-t (2) and (OSSOtBu)(ZrOBu2)-Bu-t (3) bearing OSSO-type ligands (OSSOCl-H = 1,4-dithiabutanedyl-2,2'-bis(4,6-dichlorophenol); OSSOBr-H = 1,4-dithiabutanedyl-2,2'-bis(4,6-dibromophenol); OSSOtBu-H = 1,4-dithiabutanedyl-2,2'-bis(4,6-di-tert-butyl-phenol)) were prepared and characterized. NMR spectroscopy revealed a rigid octahedral coordination geometry with a facial-facial coordination of the [OSSO] ligand to the metal complex. These compounds were active in the ring-opening polymerization of L-lactide exerting an effective control over the polymerization reaction. Activities correlated with the electron-withdrawing character of the ortho and para groups of the OSSO ligands. Density functional theory (DFT) investigations indicated that substitution with increasingly electron-withdrawing groups favors the monomer coordination and determines an earlier, more reactive transition state.

Two new nonsymmetric bis(aryl-imino)acenaphthene ligands (Ar,Ar'-BIAN) and one symmetric Ar2-BIAN were studied. The three ligands share the presence of at least one methoxy group on one of the two aryl rings. These ligands were used for the synthesis of neutral and monocationic palladium(ii) complexes of general formula [Pd(CH3)Cl(N-N)] and [Pd(CH3)(L)(N-N)][PF6] (N-N = Ar,Ar'-BIAN, Ar2-BIAN; L = CH3CN, dmso). Due to the nonsymmetric nature of the ligands and their coordination to palladium in a nonsymmetric chemical environment, cis and trans isomers are possible for the three series of complexes with Ar,Ar'-BIANs. Both a detailed NMR investigation in solution and the X-ray characterization in the solid state point out that the trans isomer is the preferred species for the neutral derivatives, whereas for the cationic compounds a decrease in the stereoselectivity of the coordination is observed. One of the new Ar,Ar'-BIANs differs from an already reported nonsymmetric α-diimine for the replacement, on one aryl ring, of a methyl group with a methoxy substituent, thus allowing a comparison of the structural features of the relevant complexes. The monocationic complexes were tested as precatalysts for the ethylene/methyl acrylate copolymerization under mild reaction conditions. Despite the structural similarities observed in solution with the already known precatalysts, the present compounds demonstrated a remarkable decrease in the productivity values associated with a higher affinity for the polar monomer.

Poly(ε-caprolactone) (PCL) is a cheap and sustainable polymer with long-term degradation (3–4 years) and low temperature transition (Tm=∼60°C). We report on the investigation of PCL as a valid green candidate for Carbon Capture and Utilization (CCU). Studies were carried out by two complementary tools: a Sievert-type volumetric apparatus, to thoroughly analyse the CO2 adsorption/desorption process inside the polymer, and Nuclear Magnetic Resonance (NMR) spectroscopy for a deeper study of the molecular dynamics and confinement effects through 13C – pulsed field gradient (PFG) method (self-diffusion measurements), relaxation times (T1) and spectral analysis. The morphology of the solid-state PCL was also investigated by Scanning Electron Microscopy (SEM). The effects of both the physical state and the adsorption process conditions on the PCL's CO2 sorption capabilities were investigated as well as those concerning the cyclic life and the regeneration process. We find that two kind of adsorption sites are present in PCL matrix. Furthermore, PCL show a remarkable and complete thermoreversibility of the CO2 adsorption process, a key condition in view of possible applications in this field.

We have successfully synthesized poly(lactide), poly(glycolide), and poly(lactide-co-glycolide) copolymers in bulk by ring-opening homo- and copolymerization of glycolide and l-lactide, using sodium hydride as the environmentally friendly and nontoxic initiator. Random copolymers were obtained, and the microstructure was characterized by nuclear magnetic resonance (1H and 13C NMR) and matrix-assisted laser desorption ionization mass spectrometry (MALDI MS). The mechanism of reaction was elucidated by analysis of the polymer end groups. Homopolymer and copolymers films and their blends were obtained, and structure and physical properties analyzed. Thermal degradation analysis showed superior characteristics of copolymers with respect to the blends. Transport properties of water vapor were also evaluated and correlated to the copolymer composition.

ABSTRACTThe aliphatic poly(esters) are the most common biodegradable and biocompatible synthetic materials used by far for diverse biomedical applications. Co‐polymers and ter‐polymers of glycolide with ε‐caprolactone and lactide are produced in the presence of dimethyl aluminum compounds, bearing salicylaldiminato bidentate ligands differing for the steric hindrance on the ortho position of the phenolato ring. The formation of random poly[glycolide‐co‐(ε‐caprolactone)] samples is favored with more encumbered catalyst. Transesterification reactions of the second mode also contribute to randomize the structure. Copolymers from semi‐crystalline to amorphous are produced by decreasing the glycolide/ε‐caprolactone feed ratio. The terpolymerization of glycolide with ε‐caprolactone and rac‐lactide with the same catalysts affords amorphous and random poly[(glycolide‐co‐lactide‐co‐(ε‐caprolactone)] samples. The incorporation of the monomers is in this case determined by the bulkiness of the catalysts and by the higher coordination ability of the cyclic diesters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42567.

The homo and co-polymerization of a large ring size lactone afforded unsaturated poly(esters), further modified to functional thermoplastic materials.

Yttrium and aluminium complexes of two dithiodiolate ligands that feature different bridges (CF3)2C(OH)CH2SRSCH2C(OH)(CF3)2 (L(1)-H2, R = CH2CH2 and L(2)-H2, R = C6H4) were synthesized in good yields by reacting tris(silylamide)yttrium or trimethylaluminium with one equivalent of the proligand. All complexes were characterized by NMR and elemental analysis, and single-crystal X-ray structural analysis was also performed for one of the yttrium complexes. The catalytic activities of the four complexes in the ring-opening polymerization of ε-caprolactone and rac-lactide have been investigated. Furthermore, DOSY experiment and DFT calculations have been carried out to determine the structure of the isopropoxo derivative of the complex L(2)Y amide.

The catalytic CO/styrene and ethylene/methyl acrylate copolymerizations are compared for the first time by applying the same precatalysts. With this aim, Pd II neutral, [Pd(CH 3 )Cl(N–N)], and monocationic, [Pd(CH 3 )(L)(N–N)][PF 6 ] (L=CH 3 CN, DMSO), complexes with 1‐naphthyl‐ and 2‐naphthyl‐substitued α‐diimines with both an acenaphthene and a diazabutadiene skeleton as chelating nitrogen‐donor ligands (N–N) have been studied. In the case of the complexes with the 1‐naphthyl‐substituted ligands, syn and anti isomers are found both in solid state and in solution. All the monocationic complexes generate active catalysts for the CO/styrene copolymerization leading to atactic or isotactic/atactic stereoblock copolymers depending on the ligand bonded to palladium. Instead, in the case of the ethylene/methyl acrylate copolymerization only the complexes with the 1‐naphthyl‐substituted ligands generate catalysts for this reaction.

The dimethylaluminum compounds Al(CH3)2[(O-2-{(C6F5)N═CH}-4,6-R2C6H2)], R = H (1) or cumyl (2), were synthesized and tested as initiators in the homo- and copolymerization of rac-lactide and glycolide. These complexes resulted active for the production of PLGA copolymers with variable microstructure. All the copolymers were fully characterized by NMR, GPC, and DSC analysis. The copolymerization reactions were performed in bulk and in solution, by varying comonomers ratio, monomer/catalyst feed ratio, temperature, reaction time, and solvent. Interestingly, by changing the reaction conditions, copolymers from random, to blocky, to diblock were obtained, demonstrating the effectiveness and versatility of such systems in modulating the copolymers microstructure and the related thermal properties.

A new nonsymmetric bis(aryl‐imino)acenaphthene (Ar‐BIAN) ligand, featured by a subtle steric and electronic unbalance of the N‐donor atoms, is reported. With the new ligand and the corresponding symmetrically substituted derivatives, both neutral and monocationic PdCH 3 compounds have been synthesized and characterized. The series of the monocationic complexes [Pd(CH 3 )(L)(Ar‐BIAN)][PF 6 ] (L=CH 3 CN, dmso) has been extended to dimethyl sulfoxide derivatives. The monocationic complexes are tested as precatalysts for the ethylene/methyl acrylate cooligomerization under mild reaction conditions of temperature and ethylene pressure. The catalytic product is a mixture of ethylene/acrylate cooligomers and higher alkenes. The catalysts containing the new nonsymmetric ligand are found to be more productive than those with the symmetric Ar‐BIANs. The Pd–dmso catalysts are more productive and show a longer lifetime than their Pd–NCCH 3 counterparts.

The reaction of the neutral Pd complex [Pd(CH(3))Cl(cod)] with the potentially terdentate 2-oxazolinyl phenanthroline ligands 1-3 affords the corresponding cationic dinuclear Pd-complexes 1a-3a, which can be isolated in the solid state in good yields. By treatment with AgPF(6) the complexes 1a-3a were converted into the corresponding hexafluorophosphate derivatives 1b-3b, where both the ligand units feature a terdentate coordination around the two Pd-centres with the phenanthroline fragment of each unit displaying a chelate coordination to one Pd-centre, while the corresponding oxazolinyl pendant acts as a bridging ligand towards the second Pd-centre. The persistence of this dimeric structure of 1b-3b in CD(2)Cl(2) solution was confirmed by (15)N-NMR experiments at natural abundance, which clearly show the binding to the metal of all of the nitrogen donors, as well as the overall C(2) symmetry of the compound. In consequence of the different strengths of the relevant ion-pair, the dimeric structure of the complex undergoes partial fragmentation in the case of the chloride derivatives 1a-3a, as evidenced from the (15)N-NMR spectra. Complexes 1b-3b are active catalysts in styrene alternate carbonylation, where, under very mild conditions (30 °C and 1 atm of CO), they provide oligomers with 3-5 repetitive units as the exclusive or prevailing product. When traces of the CO/styrene polyketones are also formed, their (13)C-NMR characterization shows that they are stereochemically homogeneous with a unique syndio-tacticity. This result implies that Pd-complexes able to induce a complete enantioface discrimination in the insertion step of the alkene during the catalytic cycle of the styrene alternate carbonylation have been produced for the first time.

A series of palladium complexes were synthesized that comprise three sterically different C,N-bidentate coordinating NHC-pyridine ligands (NHC = N-heterocyclic carbene). In one set, the pyridine and the carbene are linked by a flexible CH2 group (a); in the other two sets, the two ligand units are directly linked and feature a shielding mesityl substituent on the carbene and either an unsubstituted pyridine (b) or a xylyl-substituted pyridine unit (c). Investigation of the reactivity of cationic complexes [Pd((CN)-N-boolean AND)Me(NCMe)](+) (6), analogues to Brookhart's alpha-diimine system, toward alkenes showed a strong correlation between the catalytic activity and selectivity and the ligand setting. While 6a was inactive in ethylene conversion, 6b afforded low-molecular-weight olefins (oligomerization), and 6c produced exclusively butene (dimerization). With styrene as substrate, exclusive dimerization occurred with all three complexes. Steric and electronic factors were identified that govern the disparate activity and selectivity and that allow for efficient tailoring of the catalytic performance.

A new cationic pyridine-carbene palladium complex has been prepared that features a C,N-bidentate coordinating ligand with a shielded pyridine and a sterically less protected carbene moiety; evaluation of this complex in ethylene polymerization revealed competitive reductive elimination processes and provides guidelines for further catalyst design.