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This study aims to determine the influence of the dispersity on the aggregation of conjugated polymers and their subsequent chiral expression.

Three new tetraphenylethene (TPE) push-pull chromophores exhibiting strong intramolecular charge transfer (ICT) are described. They were obtained via [2+2] cycloaddition - retroelectrocyclization (CA-RE) click reactions on an electron-rich alkyne-tetrafunctionalized TPE (TPE-alkyne) using both 1,1,2,2-tetracyanoethene (TCNE), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as electron-deficient alkene. Only the starting TPE-alkyne displayed a significant AIE behavior, whereas for TPE-TCNE,a faint effect was observed and for TPE-TCNQ and TPE-F4-TCNQ, no fluorescence was observed in any conditions. The main ICT bands that dominate the UV-Visible absorption spectra underwent a pronounced red-shift beyond the near-infrared (NIR) region for TPE-F4-TCNQ. Based on TD-DFT calculations, it was shown that the ICT character shown by the compounds exclusively originated from the clicked moieties independently of the nature of the central molecular platform. Photothermal (PT) studies conducted on both TPE-TCNQ and TPE-F4-TCNQ in the solid state revealed excellent properties, especially for TPE-F4-TCNQ. These results indicated that CA-RE reaction of TCNQ or F4-TCNQ with donor-substituted are promising candidates for PT applications.

We investigate the scope of the organocatalyzed step-growth copolymerization of CO2-sourced exovinylene bicyclic carbonates with bio-based diols into polycarbonates. A series of regioregular poly(oxo-carbonate)s were prepared from sugar- (1,4-butanediol and isosorbide) or lignin-derived (1,4-benzenedimethanol and 1,4-cyclohexanediol) diols at 25 degrees C with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst, and their defect-free structure was confirmed by nuclear magnetic resonance spectroscopy studies. Their characterization by differential scanning calorimetry and wide-angle X-ray scattering showed that most of them were able to crystallize. When the polymerizations were carried out at 80 degrees C, some structural defects were introduced within the polycarbonate chains, which limited the polymer molar mass. Model reactions were carried out to understand the influence of the structure of alcohols, the temperature (25 or 80 degrees C), and the use of DBU on the rate of alcoholysis of the carbonate and on the product/linkage selectivity. A full mechanistic understanding was given by means of static- and dynamic-based density functional theory (DFT) calculations showing the determining role of DBU in the stability of intermediates, and its important role in the rate-determining steps is revealed. Furthermore, the origin of side reactions observed at 80 degrees C was discussed and rationalized by DFT modeling. As impressive diversified bio-based diols are accessible on a large scale and at low cost, this process of valorization of carbon dioxide gives new perspectives on the sustainable production of bioplastics under mild conditions.

Polypeptoids, consisting of nitrogen-substituted analogues of polypeptides, have become a real asset in modern sciences especially in the biomedical field. To address the increasing demand for polypeptoid structures with specific properties, this work explores the combinatorial character of the Ugi-four component polymerization of amino acid derivatives such as dipeptides and aminobutyric acid compounds with different aldehydes and isocyanides. A library of structurally diverse polypeptoids is prepared accordingly. Thermal and solution properties of the latter are characterized and discussed in a structure–property relationship approach highlighting the impact of both the backbone and side chains. Some materials demonstrate pH-responsiveness, thermo-responsiveness with tunable transition temperatures and biocompatibility. Given the great variety of possible substrates and the promising properties of the obtained polypeptoids, this straightforward and combinatorial strategy is attractive for the future development of polypeptoids and resulting applications.

An azobenzene-bridged 15-crown-5 ether (1) was successfully used as a photoswitchable cocatalyst for modulating the catalytic activity of potassium acetate (KOAc) in the ring-opening polymerization (ROP) of L-lactide (L-LA) when initiated from an exogenous alcohol. By alternating exposure to daylight and UV light, 1 transforms the K+,−OAc ion pair-like in free ions “on-demand”, resulting in an effective form of the catalytic complex. This allows the modulation of the L-LA ROP speed, switching the process from a slow to a fast state.

In this study, a new chiral α,ω-bifunctional polythiophene is synthesized and used as a nanoparticle linker molecule to synthesize the first layered conjugated polymer/nanoparticle (CP/NP) hybrid m...

In this report, the influence of heterogeneity on the chiral expression of star-shaped conjugated polymers is investigated. For this purpose, two heterogeneous star-shaped conjugated polymers, i.e....

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International audience; Surface modification of cellulose nanocrystals (CNC) by organocatalysed grafting from ring-opening polymerization (ROP) of trimethylene carbonate was investigated. Organocatalysts including an amidine (DBU), a guanidine (TBD), an amino-pyridine (DMAP) and a phosphazene (BEMP) were successfully assessed for this purpose, with performances in the order TBD > BEMP > DMAP, DBU. The grafting ratio can be tuned by varying the experimental parameters, with the highest grafting of 74 % by weight obtained under mild conditions, i.e at roomtemperature in tetrahydrofuran with a low amount of catalyst. This value is much higher than that of typical ring opening polymerizations of cyclic esters initiated from the surface of cellulose nanoparticles. Additionally, DSC analysis of the modified material revealed the presence of a glass transition temperature, indicative of a sufficient graft length to display polymeric behaviour. This is, to our knowledge, the first example of cellulose nanocrystalsgrafted with polycarbonate chains.; La modification de surface des nanocristaux de cellulose (CNC) par greffage organocatalysé à partir de la polymérisation par ouverture de cycle (ROP) du carbonate de triméthylène a été étudiée. Des organocatalyseurs comprenant une amidine (DBU), une guanidine (TBD), une amino-pyridine (DMAP) et un phosphazène (BEMP) ont été évalués avec succès dans ce but, avec des performances dans l'ordre TBD > BEMP > DMAP, DBU. Le taux de greffage peut être ajusté en faisant varier les paramètres expérimentaux, le greffage le plus élevé de 74 % en poids ayant été obtenu dans des conditions douces, c'est-à-dire à température ambiante dans du tétrahydrofurane avec une faible quantité de catalyseur. Cette valeur est beaucoup plus élevée que celle des polymérisations par ouverture de cycle typiques des esters cycliques initiées à partir de la surface des nanoparticules de cellulose. De plus, l'analyse DSC du matériau modifié a révélé la présence d'une température de transition vitreuse, indiquant une longueur de greffe suffisante pour présenter un comportement polymère. Il s'agit, à notre connaissance, du premier exemple de nanocristaux de cellulose greffés avec des chaînes de polycarbonate.

Peptoids are attractive substitutes for peptides in several research areas, especially when they adopt a helical structure. The chain-size evolution of the secondary structure of the widely studied (S)-N-1-phenylethyl peptoids is here analyzed by means of the ion mobility mass spectrometry technique increasingly used as a powerful analytical tool and is further supported by theoretical modeling. We conclude that the helical shape of the peptoids prevailing in solution is lost in the gas phase by the need to screen the positive charge borne by the peptoid even though the collisional cross sections are close to the values expected for helical systems. We further illustrate that trend line analyses predicting molecular shapes from fits of the size evolution of cross sections can be very misleading since they critically depend on the range of polymerization degrees under study.

Mass spectrometric techniques and more particularly collision-induced dissociation (CID) experiments represent a powerful method for the determination of the primary sequence of (bio)molecules. However, the knowledge of the ion fragmentation patterns say the dissociation reaction mechanisms is a prerequisite to reconstitute the sequence based on fragment ions. Previous papers proposed that protonated peptoids dissociate following an oxazolone-ring mechanism starting from the O-protonation species and leading to high mass Y sequence ions. Here we revisit this backbone cleavage mechanism by performing CID and ion mobility experiments, together with computational chemistry, on tailor-made peptoids. We demonstrated that the B/Y cleavages of collisionally activated O-protonated peptoids must involve the amide nitrogen protonated structures as the dissociating species, mimicking the CID behavior of protonated peptides. Upon the nucleophilic attack of the oxygen atom of the N-terminal adjacent carbonyl group on the carbonyl carbon atom of the protonated amide, the peptoid ions directly dissociate to form an ion-neutral complex associating an oxazolone ion to the neutral truncated peptoid residue. Dissociation of the ion/neutral complex predominantly produces Y ions due to the high proton affinity of the secondary amide function characteristic of truncated peptoids. Whereas the production of Yx ions from acetylated peptoids also involves the B/Y pathway, the observation of abundant Yx ions from non-acetylated peptoid ions is shown in the present study to arise from an A1-Yx mechanism. The consecutive and competitive characters of the A1-Yx and the B/Y mechanisms are also investigated by drift time-aligned CID experiments.

The synthesis of ethylene-based block copolymers (BCPs) by using a single radical polymerization technique is attractive but remains to be a great challenge. The main difficulty relates to the diff...

Polymers produced with the most used controlled polymerization method with the simplest initiators, namely the Kumada catalyst transfer condensation polymerization (KCTCP) with Ni2+ salts, all have...

An increasing number of studies take advantage of ion mobility spectrometry (IMS) coupled to mass spectrometry (IMS-MS) to investigate the spatial structure of gaseous ions. Synthetic polymers occupy a unique place in the field of IMS-MS. Indeed, due to their intrinsic dispersity, they offer a broad range of homologous ions with different lengths. To help rationalize experimental data, various theoretical approaches have been described. First, the study of trend lines is proposed to derive physicochemical and structural parameters. However, the evaluation of data fitting reflects the overall behavior of the ions without reflecting specific information on their conformation. Atomistic simulations constitute another approach that provide accurate information about the ion shape. The overall scope of this review is dedicated to the synergy between IMS-MS and theoretical approaches, including computational chemistry, demonstrating the essential role they play to fully understand/interpret IMS-MS data.

Magnetron sputter deposition of metal targets over liquids allows producing colloidal solutions of small metal nanoparticles (NPs) without any additional reducing or stabilizing reagents. Despite that this synthetic approach is known for almost 15 years, the detailed mechanism of NP formation is still unclear. Detailed investigations must be carried out to better understand the growth mechanism and, ultimately, control the properties of the NPs. Here, the combination of the gold (Au) target and castor oil, a highly available green solvent, was chosen as a model system to investigate how different experimental parameters affect the growth of NPs. The effect of deposition time, applied sputter power, working gas pressure, and type of sputter plasma (direct current magnetron sputtering (DC-MS) vs. high-power impulse magnetron sputtering (HiPIMS)) on properties of Au NPs has been studied by UV-vis spectroscopy and transmission electron microscopy (TEM), and further supported by quantum-chemistry calculations and mass-spectrometry analysis. The mechanism of the Au NP formation includes the production of primary NPs and their subsequent aggregative growth limited by diffusion in the viscous castor oil medium. Final Au NPs have a narrow size distribution and a medium diameter of 2.4–3.2 nm when produced in DC-MS mode. The NP size can be increased up to 5.2 ± 0.8 nm by depositing in HiPIMS mode which, therefore, mimics energy and time-consuming post synthesis annealing.

Folding and unfolding processes are key aspects that should be mastered for the design of foldamer molecules for targeted applications. In contrast to the solution phase, in vacuo conditions represent a well-defined environment to analyze the intramolecular interactions that largely control the folding/unfolding dynamics. Ion mobility mass spectrometry coupled to theoretical modeling represents an efficient method to decipher the spatial structures of gaseous ions, including foldamers. However, charge solvation typically compacts the ion structure in the absence of strong stabilizing secondary interactions. This is the case in peptoids that are synthetic peptide regioisomers whose side chains are connected to the nitrogen atoms of the backbone instead of α-carbon as in peptides, thus implying the absence of H-bonds among the core units of the backbone. A recent work indeed reported that helical peptoids based on Nspe units formed in solution do not retain their secondary structure when transferred to the gas phase upon electrospray ionization (ESI). In this context, we demonstrate here that the helical structure of peptoids bearing (S)-N-(1-carboxy-2-phenylethyl) bulky side chains (Nscp) is largely preserved in the gas phase by the creation of a hydrogen bond network, induced by the presence of carboxylic moieties, that compensates for the charge solvation process.

The attachment of conjugated polymers (CPs), characterized by their optical and electronic properties and excellent processability, to inorganic nanoparticles (NPs), known for their specialized ele...

Modern mass spectrometry methods provide a huge benefit to saponin structural characterization, especially when combined with collision-induced dissociation experiments to obtain a partial description of the saponin (ion) structure. However, the complete description of the structures of these ubiquitous secondary metabolites remain challenging, especially since isomeric saponins presenting small differences are often present in a single extract. As a typical example, the horse chestnut triterpene glycosides, the so-called escins, comprise isomeric saponins containing subtle differences such as cis-trans ethylenic configuration (stereoisomers) of a side chain or distinct positions of an acetyl group (regioisomers) on the aglycone. In the present paper, the coupling of liquid chromatography and ion mobility mass spectrometry has been used to distinguish regioisomeric and stereoisomeric saponins. Ion mobility arrival time distributions (ATDs) were recorded for the stereoisomeric and regioisomeric saponin ions demonstrating that isomeric saponins can be partially separated using ion mobility on a commercially available traveling wave ion mobility (TWIMS) mass spectrometer. Small differences in the ATD can only be monitored when the isomeric saponins are separated with liquid chromatography prior to the IM-MS analysis. However, gas phase separation between stereoisomeric and regioisomeric saponin ions can be successfully realized, without any LC separation, on a cyclic ion mobility-enabled quadrupole time-of-flight (Q-cIM-oaToF) mass spectrometer. The main outcome of the present paper is that the structural analysis of regioisomeric and stereoisomeric natural compounds that represents a real challenge can take huge advantages of ion mobility experiments but only if increased ion mobility resolution is attainable.

Multiblock copolymers represent fascinating architectures that are generally prepared from heterofunctional initiators through independent polymerization processes. So far, most of those processes ...

International audience; We report a novel class of star-shaped multiazobenzene photoswitches comprising individual photochromes connected to a central trisubstituted 1,3,5-benzene core. The unique design of such C3-symmetric molecules, consisting of conformationally rigid and pseudoplanar scaffolds, made it possible to explore the role of electronic decoupling in the isomerization of the individual azobenzene units. The design of our tris-, bis-, and mono(azobenzene) compounds limits the π-conjugation between the switches belonging to the same molecule, thus enabling the efficient and independent isomerization of each photochrome. An in-depth experimental insight by making use of different complementary techniques such as UV–vis absorption spectroscopy, high performance liquid chromatography, and advanced mass spectrometry methods as ion mobility revealed an almost complete absence of electronic delocalization. Such evidence was further supported by both experimental (electrochemistry, kinetical analysis) and theoretical (DFT calculations) analyses. The electronic decoupling provided by this molecular design guarantees a remarkably efficient photoswitching of all azobenzenes, as evidenced by their photoisomerization quantum yields, as well as by the Z-rich UV photostationary states. Ion mobility mass spectrometry was exploited for the first time to study multiphotochromic compounds revealing the occurrence of a large molecular shape change in such rigid star-shaped azobenzene derivatives. In view of their high structural rigidity and efficient isomerization, our multiazobenzene photoswitches can be used as key components for the fabrication of complex stimuli-responsive porous materials.

Due to their great modularity, ease of implementation, and atom economy, multicomponent reactions (MCRs) are becoming increasingly popular macromolecular engineering tools. In this context, MCRs suitable in polymer synthesis are eagerly searched for. This work demonstrates the potential of the Ugi-three component reaction (Ugi-3CR) for the design of polymers and, in particular, of poly(α-amino amide)s. A series of polymers containing amino and amido groups within their backbone were obtained through a one-pot process by reacting aliphatic or aromatic diamines, diisocyanides, and aldehydes. The impact of temperature, concentration, catalyst loading, and substrates on polymerization efficiency is discussed. A preliminary study on the thermal properties and the solution behavior of these poly(α-amino amide)s was carried out. An aliphatic-rich derivative notably showed some pH-responsiveness in water via protonation-deprotonation of its amino groups.

Peptoids constitute an emergent class of synthetic biocompatible macromolecules that are best described as polymers of N-substituted glycines. Peptides and peptoids are regioisomers with the side chains appended in peptoids to the nitrogen atoms rather than to the α-carbon atoms as in peptides. Peptide sequencing now takes great advantage of collision-induced dissociation experiments, based on the elucidation of the decomposition pathways of protonated peptides. In contrast, data on peptoid ion decompositions are to date scarcely present in the literature. Upon CID, protonated peptoids were recently shown to mostly dissociate by cleavages at the backbone amide bonds yielding B- and Y-fragment ions. In addition, the loss of the side-chain group and/or the formation of the side-chain fragment ion are common reactions for peptoids containing protonated N-α-aromatic side chain. In the present paper, we submitted protonated tailor-made peptoids to (energy-resolved) collision-induced dissociation experiments to investigate the side-chain loss reaction mechanisms. We also used orthogonal methods, such as quantum chemistry, ion mobility spectrometry and infrared photodissociation spectroscopy to establish the structures of the fragment ions. We ended up with different mechanistic scenarios consistent with the nature of the fragment ions and the kinetic energy dependence of decomposition reactions. Our mechanistic proposals associate the proton mobile model, proton bound dimer intermediacy and concerted rearrangement reactions.

Recent studies point to an additional stability of metal-complexed functionalized hydrocarbon chains. This additional stabilization is suggested to arise from a bidentate complexation of the metal cation with both the functional group and aliphatic chain, leading to more folded structures. In the present work, this issue is verified for silver complexed alkylamines by tandem mass spectrometry and ion mobility experiments combined with quantum-chemical calculations. Upon increasing the length of the hydrocarbon chains, the alkylamine/silver complexes undergo a structural transition to reach a folded structure in which the silver cation interacts with both the amine group and hydrogen atoms located at the chain end. This folding is further examined by monitoring the loss of AgH upon collision-induced dissociation experiments performed on alkylamines with different chain lengths. Ion mobility experiments performed on the fragment ions indicate that the removal of the silver cation induces the unfolding of the chain.

Through the incorporation of chiral and achiral poly(3-alkylthiophenes) (P3ATs) into a star-shaped system, a well-defined supramolecular organization is obtained lacking the unfavorable linear lamellar structure typically obtained for P3AT. Through the combination of a controlled chain-growth polymerization and efficient postpolymerization and click reactions, well-defined star-shaped P3ATs with a low dispersity of 1.1 were obtained. The combination of UV–vis, circular dichroism (CD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) measurements showed the formation of a strong (chiral) supramolecular organization into fibers, different and stronger than those obtained with the linear P3ATs. The fact that the width of the fibers is in good agreement with the width of a single star-shaped P3AT excludes the formation of a linear lamellar structure. Furthermore, the particular supramolecular organization of the star-shaped polymers, which appears thanks to the precision polymer synth...

The research area of nonlinear topologies of conjugated polymers (CPs) became a topic of growing interest due to their unique optoelectronic properties compared to CPs with linear topologies. Nonetheless, the field of the third-order nonlinear optical response (TONO) is still largely unexplored, although, theoretically, nonlinear CPs should give a higher TONO response. Therefore, linear CPs and a trigonal nonlinear CP were synthesized via a combination of a controlled chain-growth polymerization, post-polymerization reactions and a click reaction. Afterward, the TONO response of the CPs was investigated with the highly sensitive third-harmonic scattering technique using solvatochromism experiments. In contrast to what was expected, trigonal nonlinear CPs do not possess a higher TONO response compared to their linear counterparts.

International audience; Pseudomonas aeruginosa is a human pathogen belonging to the top priorities for the discovery of new therapeutic solutions. Its propensity to generate biofilms strongly complicates the treatments required to cure P. aeruginosa infections. Herein we describe the synthesis of a series of novel rotaxanes comprised of a central galactosylated pillar [5]arene, a tetrafucosylated dendron and a tetra-guanidinium subunit. Strategically, we exploited a supramolecular assembly technology to generate complex rotaxanes from relatively simple subcomponents. The final glycorotaxanes displayed high affinity for the two P. aeruginosa lectins LecA and LecB as evaluated by Isothermal Titration Calorimetry. Potent inhibition levels of P. aeruginosa biofilm growth were evidenced showing that the three subunits of the glycorotaxanes work synergistically. Such antibiofilm potency had rarely been reached in the literature. Importantly, none of the final rotaxanes was bactericidal, showing that their antibiofilm activity is lectinmediated but does not depend on bacteria killing, which is a rare feature for antibiofilm agents.

International audience; Research toward bio-based polymers is an expanding field due to environmental concerns. A library of new aliphatic diol-diamide monomers with different chain lengths between the two amido groups was synthesized from sustainable levulinic acid and various linear aliphatic diamines (C 2-C 10). The monomers were prepared by diacylation of the diamines followed by reduction of the ketones to alcohols. These secondary diols were successfully recognized by an enzyme and polymerised in solution through a lipase-catalysed polycondensation. Poly(ester-co-amide)s with number-average molecular weights (M n) in the range of 1300-7200 g mol −1 were obtained, with dispersities between 1.5 and 1.8. An improvement of the M n value was observed upon increasing the monomer chain length. The variation of the aliphatic diol allows modulating the thermal properties of the final polymers. The glass transition temperatures were found to be between −23°C and 0°C. The polymers containing a long aliphatic segment (C 8-C 10) were able to crystallize (melting temperature of 90-97°C). TGA analyses showed that the ester linkages degrade at lower temperatures than the amide bonds. The stability of the latter was found to be higher when the number of methylene units increased from 2 (355°C) to 10 (378°C). This kind of biopolymer could be used as a drug delivery system or for tissue engineering applications. † Electronic supplementary information (ESI) available. See

The epimerization of polylactide is reported in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 105°C in toluene. The extent of the reaction depends on the amount of TBD introduced and the reaction time. Up to ca. 46% D units can be formed starting from poly(L-lactide) in the presence of 5 mol% TBD. The epimerization rate is slightly higher for D-stereoisomers vs. L-stereoisomers. From the decrease of the number-average molecular weight observed, a concomitant chain scission reaction is observed. A possible mechanism based on a nucleophilic attack of TBD is proposed based on NMR analyses, notably DOSY, MALDI ToF mass spectrometry and IR spectroscopy. The implications of the work in the field of polymer synthesis and chemical recycling of polylactide are discussed. 181;109188

Synthetic polymers occupy a unique place in the field of ion mobility mass spectrometry (IMS-MS). Indeed, due to their intrinsic dispersity, they have the asset to offer a broad range of homologous ions with different lengths that can be detected in several charge states. In addition, the gas-phase structure of polymer ions mostly depends on their ability to screen the adducted charges. Several works dealing with linear, cyclic, and star-shaped polymers have already shown that the gas-phase structure of polymer ions heavily relies on the polymer architecture, i.e., the primary structure. In the present work, we move a step further by evaluating whether a relationship exists between the primary and secondary structures of synthetic homo and copolymers. The IMS-MS experiments will be further complemented by MD simulations. To highlight the effectiveness of IMS separation, we selected isomeric homo and copolymers made of lactide (LA) and propiolactone (PL) units. In this way, the mass analysis becomes useless since isomeric comonomer sequences can coexist for any given chain length. An UPLC method was implemented in the workflow to successfully separate all PL-LA comonomer sequences before infusion in the IMS-MS instrument. The analysis of doubly charged copolymers showed that the comonomer sequence has an impact on the IMS response. However, this only holds for copolymer ions with precise sizes and charge states, and this is therefore not a rule of thumb.

The stereoisomerically pure synthesis of a novel heptanuclear Ru(II)–Os(II) antenna bearing multitopic terpyridine ligands is reported. An unambiguous structural characterization was obtained by 1H NMR spectroscopy and ion mobility spectrometry (IMS-MS). The heptanuclear complex exhibits large molar absorption coefficients (77900 M–1 cm–1 at 497 nm) and undergoes unitary, downhill, convergent energy transfer from the peripheral Ru(II) subunits to the central Os(II) that displays photoluminescence with a lifetime (τ = 161 ns) competent for diffusional excited-state electron transfer reactivity in solution.

Among the various catalysts that can be used for polycondensation reactions, enzymes have been gaining interest for three decades, offering a green and eco-friendly platform towards the sustainable design of renewable polyesters. However, limitations imposed by their delicate nature, render them less addressed. As a case study, we compare herein bulk and solution polycondensation of 1,6-hexanediol and diethyl adipate catalyzed by an immobilized lipase from Candida antarctica. The influence of various parameters including time, temperature, enzyme loading, and vacuum was assessed in the frame of a two-step polymerization with the help of response surface methodology, a statistical technique that investigates relations between input and output variables. Results in solution (diphenyl ether) and bulk conditions showed that a two-hour reaction time was enough to allow adequate oligomer growth for the first step conducted under atmospheric pressure at 100 &deg, C. The number-average molecular weight (Mn) achieved varied between 5000 and 12,000 g&middot, mol&minus, 1 after a 24 h reaction and up to 18,500 g∙mol&minus, 1 after 48 h. The statistical analysis showed that vacuum was the most influential factor affecting the Mn in diphenyl ether. In sharp contrast, enzyme loading was found to be the most influential parameter in bulk conditions. Recyclability in bulk conditions showed a constant Mn of the polyester over three cycles, while a 17% decrease was noticed in solution. The following work finally introduced a statistical approach that can adequately predict the Mn of poly(hexylene adipate) based on the choice of parameter levels, providing a handy tool in the synthesis of polyesters where the control of molecular weight is of importance.

The synthesis of well-defined propargyl-functional aliphatic polycarbonates is achieved via the organocatalytic ring-opening polymerization of prop-2-yn-1-yl 2-oxo-1,3,6-dioxazocane-6-carboxylate (P-8NC) using a wide variety of commercially available or readily made, shelf-stable organocatalysts. The resulting homopolymers show low dispersities and end-group fidelity, with the versatility of the system being demonstrated by the synthesis of telechelic copolymers and block copolymers with molar mass up to 40 kDa.

A degradable polyphthalaldehyde-polystyrene block copolymer generated by modular ligation is reported for the first time serving as a nanochannel template for the formation of nanostructured materials. The polyphthalaldehyde-b-polystyrene copolymer was spin-coated onto a surface with subsequent polyphthalaldehyde block removal. Block conjugation and block removal were confirmed by H-NMR, SEC, AFM, and SEM.

Recent advances in molecular dynamics (MD) simulations have made it possible to examine the behavior of large charged droplets that contain analytes such as proteins or polymers, thereby providing insights into electrospray ionization (ESI) mechanisms. In the present study, we use this approach to investigate the release of polylactide (PLA) ions from water/acetonitrile ESI droplets. We found that cationized gaseous PLA ions can be formed via various competing pathways. Some MD runs showed extrusion and subsequent separation of polymer chains from the droplet, as envisioned by the chain ejection model (CEM). On other occasions the PLA chains remained inside the droplets and were released after solvent evaporation to dryness, consistent with the charge residue model (CRM). Following their release from ESI droplets, the nascent gaseous PLA ions were subjected to structural relaxation for several μs in vacuo. The MD conformations generated in this way for various PLA charge states compared favorably to experimental results obtained by ion mobility spectrometry-mass spectrometry (IMS-MS). The structures of all PLA ions evolved during relaxation in the gas phase. However, some macroion species retained features that resembled their nascent structures. For this subset of ions, the IMS-MS response appears to be strongly correlated with the ESI release mechanism (CEM vs. CRM). The former favored extended structures, whereas the latter preferentially generated compact conformers.

We report the synthesis, characterization and biological profile of new bis-triazoled cyclopolylactides (c-PLA, c-PLA-FA, c-PLA-Rhod) obtained by an optimized combination of ROP and click chemistry reactions. Cyclo-PLA having a number average molecular weight of 6000 g mol−1 and a polydispersity index of 1.52 was synthetized by click ring-closure of well-defined α,ω-heterodifunctional linear precursors, followed by quaternarization of N3-triazole nodes, and subsequent CuAAC with azido-folate and azido-rhodamine yielding jellyfish-shaped c-PLA-FA and c-PLA-Rhod. Salinomycin (Sal) was loaded into jellyfish-shaped c-PLA-FA and c-PLA-Rhod nanoparticles (NPs) by nanoprecipitation, with a good encapsulation efficiency (79% and 84%, respectively) and loading content (7.1% and 7.6%, respectively). The biological studies focused on their antiproliferative effects on osteosarcoma bulk MG63 and cancer stem cells (CSCs). The cycloPLA-based NPs, with a size ranging between 125 and 385 nm, killed CSCs and MG63, with a higher efficacy on CSCs; they (unloaded or Sal-loaded) evoked on CSCs a cellular response similar to the payload, with a higher effect than the free Sal. Internalization studies indicated a fast cellular uptake (within 2 h) and sarcospheres remained fluorescent till 72 h. To the best of our knowledge, this is the first study reporting anti-CSCs properties of cycloPLA with jellyfish architecture and we believe could contribute to the development of effective strategies for osteosarcoma targeting.

Reactive extrusion and magnesium (II) N-heterocyclic carbene catalyst are successfully employed in continuous polylactide synthesis. The possibility of using six-membered N-heterocyclic carbene adducts to act as efficient catalysts towards the sustainable synthesis of poly(l-lactide) through ring-opening polymerization of l-lactide (LA) is first investigated in bulk batch reactions. Under optimized solvent-free conditions, polylactide (PLA) of moderate to high molecular weights and excellent optical activities are successfully achieved. These promising results are further applied in the continuous production of PLA in an extruder.

Photodynamic therapeutic agents are of key interest in developing new strategies to develop more specific and efficient anticancer treatments. In comparison to classical chemotherapeutic agents, the activity of photodynamic therapeutic compounds can be finely controlled thanks to the light triggering of their photoreactivity. The development of type I photosensitizing agents, which do not rely on the production of ROS, is highly desirable. In this context, we developed new iridium(III) complexes which are able to photoreact with biomolecules; namely, our Ir(III) complexes can oxidize guanine residues under visible light irradiation. We report the synthesis and extensive photophysical characterization of four new Ir(III) complexes, [Ir(ppyCF3)2(N^N)]+ [ppyCF3 = 2-(3,5-bis(trifluoromethyl)phenyl)pyridine) and N^N = 2,2'-dipyridyl (bpy); 2-(pyridin-2-yl)pyrazine (pzpy); 2,2'-bipyrazine (bpz); 1,4,5,8-tetraazaphenanthrene (TAP)]. In addition to an extensive experimental and theoretical study of the photophysics of these complexes, we characterize their photoreactivity toward model redox-active targets and the relevant biological target, the guanine base. We demonstrate that photoinduced electron transfer takes place between the excited Ir(III) complex and guanine which leads to the formation of stable photoproducts, indicating that the targeted guanine is irreversibly damaged. These results pave the way to the elaboration of new type I photosensitizers for targeting cancerous cells.