Raimondo Germani

Chemical recycling of plastics holds great promise but remains constrained by sustainability issues, with polyethylene terephthalate (PET) epitomizing this challenge. Herein, we introduce a conceptually novel strategy that overcomes PET's intrinsic hydrophobicity by physically re‐engineering the polymer's microstructure to enable ultrafast alkaline hydrolysis under exceptionally mild conditions. We leverage the ability of propylene carbonate (PC)—an inexpensive, commercial, green solvent—to selectively dissolve PET, to thermally induce phase separation, and subsequently act as a carrier for water insertion between polymer chains. Upon complete PC replacement, the water uptake exceeds twice the polymer mass, preventing chain re‐compaction and establishing an interfacial environment that facilitates hydroxyl ion diffusion to ester bonds and depolymerization with minimal alkali consumption. As a result, water‐swollen PET fully depolymerizes (96% TPA yield) at atmospheric pressure within 5 min at 90 or under 2 h at room temperature, vastly outperforming conventional hydrolysis methods. The process achieves a 20‐fold reduction in energy footprint versus direct PET hydrolysis. It performs robustly on challenging, real‐world feedstocks—including textiles and mixed plastic waste—enabling selective depolymerization unaffected by PET crystallinity. A techno‐economic analysis (TEA) confirms energy efficiency and strong economic feasibility, demonstrating overall competitiveness with existing engineered technologies. Beyond PET, the physical mechanism underpinning the strategy offers a scalable and sustainable platform for recycling a wide range of condensation polymers.

Chemical recycling of plastics holds great promise but remains constrained by sustainability issues, with polyethylene terephthalate (PET) epitomizing this challenge. Herein, we introduce a conceptually novel strategy that overcomes PET's intrinsic hydrophobicity by physically re‐engineering the polymer's microstructure to enable ultrafast alkaline hydrolysis under exceptionally mild conditions. We leverage the ability of propylene carbonate (PC)—an inexpensive, commercial, green solvent—to selectively dissolve PET, to thermally induce phase separation, and subsequently act as a carrier for water insertion between polymer chains. Upon complete PC replacement, the water uptake exceeds twice the polymer mass, preventing chain re‐compaction and establishing an interfacial environment that facilitates hydroxyl ion diffusion to ester bonds and depolymerization with minimal alkali consumption. As a result, water‐swollen PET fully depolymerizes (96% TPA yield) at atmospheric pressure within 5 min at 90 or under 2 h at room temperature, vastly outperforming conventional hydrolysis methods. The process achieves a 20‐fold reduction in energy footprint versus direct PET hydrolysis. It performs robustly on challenging, real‐world feedstocks—including textiles and mixed plastic waste—enabling selective depolymerization unaffected by PET crystallinity. A techno‐economic analysis (TEA) confirms energy efficiency and strong economic feasibility, demonstrating overall competitiveness with existing engineered technologies. Beyond PET, the physical mechanism underpinning the strategy offers a scalable and sustainable platform for recycling a wide range of condensation polymers.

The exploration of singlet fission (SF) promises a pathway to many leaps forward including more efficient solar energy extraction and, more recently, organic-based quantum computing. Our study, through a joint experimental and computational approach, revolves around 1,4-bis(p-nitro-β-styryl)benzene (1) as the smallest molecule where the intramolecular transformation of the initially allowed 1¹Bu singlet state to the 2¹Ag excited state stops being ordinary internal conversion and becomes the first half of the SF process. Herein, we experimentally observe explicit breaking of the Kasha rule. Using femtosecond broadband fluorescence upconversion, we measure a dual fluorescence of 1 in solution from its two lowest singlet excited states of different symmetry. Femtosecond transient absorption (TA) and fluorescence upconversion spectroscopy of 1 in toluene reveal ultrafast (17 ± 5 ps), almost quantitative interconversion between 1¹B and 2¹A states. A sensitization bracketing experiment with ns-TA is used to analyze the T₁ state of 1. Employing high-level ab initio extended multi-configuration quasi-degenerate 2nd-order perturbation theory (XMCQDPT2) calculations, we accurately model ground- and excited-state potential energy surfaces. 1¹B states are predominantly described by ordinary HOMO–LUMO excitation. 2¹A states can be projected in localized frontier molecular orbitals as an intramolecular strongly coupled triplet biexciton [¹(T₁T₁)] with the inclusion of intramolecular charge-transfer states. Moreover, the experimental resemblance of 2¹A and T₁ absorption is elucidated. The fluorescence temperature-dependence experiment further corroborates the XMCQDPT2 model accurate prediction of the 1¹B and 2¹A low barrier of crossing (ca. 600 cm⁻¹). The concentration-dependent experiment shows a dramatic increase in triplet yield: up to 200% yield is obtained by ns-TA quantitative measurements. All the obtained results suggest the occurrence of an SF mechanism for the triplet production: intramolecular ¹(T₁T₁) formation followed by intermolecular triplet separation aided by entropy and spatial separation.

Facile procedures exploiting three-component reactions were developed to regioselectively obtain 2-amino-7-methyl-5-phenyl- and 2-amino-5-methyl-7-phenyl-[1,2,4]triazolo[1,5-a]pyrimidine analogues bearing a C-6 electron withdrawing group.

We describe an alternative and more sustainable method for the synthesis of 2,2’‐disubstituted 3,3’‐biindoles starting from 2,2’‐diaminotolanes and (hetero)arylaldehydes. The key feature of the approach is the use of an acidic Deep Eutectic Solvent (DES) able to exploit a double activity, i. e., solvent and Brønsted Acid (BA) catalyst, avoiding the use of Volatile Organic Compounds (VOCs) as solvents and additional acid catalysts. By this way, we synthesized twenty‐five biindoles, including eighteen new compounds. The reactions run quickly under mild conditions by microwave heating at 70 °C, with yields ranging from good to very good. The reaction scope is rather broad. The medium demonstrated to be reusable at least five times with only a slight reduction in yields. Based on experimental evidence and previous literature findings, a plausible mechanism is proposed.

Deep Eutectic Solvents (DESs) are a class of solvents that are increasing their relevance in the research activity thanks to their environmental-friendly features as well as to their structural characteristics and catalytic properties. Formed by no-solvent mixing of two substances, namely a hydrogen bond donor and a hydrogen bond acceptor, DESs are finding fruitful applications in many different topics as alternatives to common organic compounds. In this work the realization, the characterization and the solubility applications of a novel water- based class of DESs are proposed. These innovative liquids, called aquo-DESs, are binary mixtures of water with glycolic acid (GA) and with trimethylglycine (TMG): GA/H2O (1/4 molar ratio) and TMG/H2O (1/5 molar ratio). The DES identity of these mixtures was demonstrated by: shifts both in terms of the molar fraction and of the melting points in the experimental melting point curves from the theoretical ones; amounts of components over their reported maximum solubility in water; thermogravimetric profiles compared to the pure substances. The aquo-DESs were characterized in their viscosity and ionic conductivity in the temperature range 20-55 C, showing really low viscosity and low ionic conductivity, with a peculiar behavior of the ionic conductivity of GA/H2O DES. The solubilizing properties of aminoacids, phenols and carboxylic acids showed peculiar really high values whenever the solute can participate to the DES as DES component itself.

Deep Eutectic Solvents (DESs) are experiencing growing interest as substitutes of polluting organic solvents for their low or absent toxicity and volatility. Moreover, they can be formed with natural bioavailable and biodegradable molecules; they are synthesized in absence of hazardous solvents. DESs are, inter alia, successfully used for the extraction/preconcentration of biofunctional molecules from complex vegetal matrices. Onion skin is a highly abundant waste material which represents a reservoir of molecules endowed with valuable biological properties such as quercetin and its glycosylated forms. An efficient extraction of these molecules from dry onion skin from “Dorata di Parma” cultivar was obtained with water dilution of acid-based DESs. Glycolic acid (with betaine 2/1 molar ratio and L-Proline 3/1 molar ratio as counterparts) and of p-toluensulphonic acid (with benzyltrimethylammonium methanesulfonate 1/1 molar ratio)-based DESs exhibited more than 3-fold higher extraction efficiency than methanol (14.79 µg/mL, 18.56 µg/mL, 14.83 µg/mL vs. 5.84 µg/mL, respectively). The extracted quercetin was also recovered efficaciously (81% of recovery) from the original extraction mixture. The proposed extraction protocol revealed to be green, efficacious and selective for the extraction of quercetin from onion skin and it could be useful for the development of other extraction procedures from other biological matrixes.

Excited-state twisting in quadrupolar pyridinium derivatives proved necessary to uncouple the donor (D) and acceptor (A⁺) groups, and reach a structurally, as well as electronically, symmetry broken intramolecular charge transfer (SB-ICT) state.

A number of quaternary ammonium salts with bulky hydrophobic moieties are known to provoke the superactivation of α-chymotrypsin (α-CT) in aqueous solution. In particular, benzyl-substituted ammonium and dicationic ammonium-based salts have recently emerged as promising classes of compounds to induce α-CT superactivation and stabilization. Preliminary in silico modelling suggested the α-CT residue tryptophan 215 to be the major anchor point of these additives. In order to achieve a broader knowledge of the enzyme–additive interactions and to validate the modelling studies, new ammonium-based additives were designed and tested. The hydrophobic interaction resulted in being critical to improving superactivation, with [(2,3,5,6-tetramethyl-p-phenylene)dimethylene]bis[triethylammonium bromide] (bisEDuEAB) resulting as the most effective quaternary ammonium superactivating agent studied so far. Finally, a general agreement between in silico outcomes and kinetic parameters was observed, and data interpretation is discussed based on the proposed α-CT/additive binding modes.