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Grisaille was the first paint applied on stained-glass panels, used in Europe since the twelfth century. Historical written sources described the use of iron and copper together with a high lead-silica base glass in the grisailles production. This project aims to study the evolution of the grisaille paint composition throughout time and the changes in the raw materials used in their production using non-destructive and non-invasive techniques. To achieve this objective, 23 grisaille samples dated from the 13th to the twentieth centuries from nine different countries (Portugal, Poland, United Kingdom, Sweden, Norway, Belgium, Low Countries, Germany, and France) were studied by means of micro particle-induced X-ray emission (μ-PIXE), micro energy dispersive X-ray fluorescence (μ-EDXRF), laser-induced breakdown spectroscopy (LIBS), laser-induced fluorescence (LIF), non-linear optical microscopy (NLOM) in the modality of multiphoton excitation fluorescence (MPEF) and optical microscopy (OM). The results showed that it was possible to identify compositional differences and patterns throughout the samples when compared with literature results. The preference for using copper in central and south-central European countries and the addition of new compounds (CoO, Cr2O3, MnO) as colouring agents since the nineteenth century was verified. The LIBS analyses allow the identification of boron on two samples, confirming the change of base glass components since the seventeenth century. The NLOM-MPEF showed the capability of this technique to measure the grisaille paint layers’ thickness. This non-invasive multi-analytical and complementary approach proves itself efficient in identifying changes in the grisaille’s composition throughout time, which can be interpreted as changes in the raw materials and manufacture used in the production of these paint materials., This research has been funded by the H2020 European project IPERION HS (Integrated Platform for the European Research Infrastructure ON Heritage Science, GA 871034), by the Spanish State Research Agency (AEI) through project PID2019-104124RB-I00/AEI/, by the Fundação de Ciência e Tecnologia de Portugal (project ref. UIDB/EAT/00729/2020, UIDP/00729/2020, LA/P/0008/2020, UIDB/ 04349/2020 and PTDC/ART-PER/1702/2021, researcher grant CEECIND/02249/2021 and doctoral grant ref. PD/BD/136673/2018) and by project TOP Heritage-CM (S2018/NMT-4372) from Community of Madrid.

Funding Information: This research was funded by the Portuguese Science Foundation [Fundação para a Ciência e Tecnologia, Ministério da Educação e da Ciência (FCT/MCTES)], through doctoral programme CORES-PD/00253/2012, and PhD Grants awarded to Márcia Vieira [SFRH/BD/148729/2019] and Hermine Grigoryan [PD/BD/142886/2018]; Project STEMMA (“From singing to writing—survey on material production and routes of Galician-Portuguese Lyric”, PTDC/LLT-EGL/30984/2017); Polyphenols in Art—Chemistry and biology hand in hand with conservation of cultural heritage, PTDC/QUI-OUT/29925/2017, as well as "Pruevalo e veras ques çierto. Recetas y conocimientos de la sociedad medieval para el siglo XXI | "Try it and you will see thats true. Recipes and konwledges from medieval society to 21th century", PID2019-108736 GB-I00, Ministerio de Ciencia e Innovación. N. Teixeira and V. Otero acknowledge FCT for CEECIND/00025/2018/CP1545/CT0009 and 2020.00647.CEECIND, respectively; R. J. Díaz Hidalgo, posdoctoral UCO 2020, La producción documental y libraría al Ándalus siglos XIII XV, Plan Propio de Investigación de la Universidad de Córdoba; Associate Laboratory for Green Chemistry- LAQV financed by FCT/MCTES (UID/QUI/50006/2019 and UIDB/50006/2020) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01–0145-FEDER-007265). Publisher Copyright: © 2023, The Author(s). For the first time, this paper systematises the medieval preparation of black writing inks found in the important thirteenth century Andalusian technical treatise written by Muhammad ibn Idrīs ibn al-Qalalūsī (1210–1308). We present the Arabic version of this extraordinary text (‘The gifts of the wise men on the curiosities of the substances’), and its first English translation, as well as discuss key aspects of the processes that remain missing or are unclear indications. In this work, we studied the iron gall inks based on galls, where no other phenolic source is present. In this pedagogical treatise, the recipes for these black iron-gall inks are organised and classified by the gallnuts extraction method used: boiling (decoction), squeezing and infusion, with water being the only solvent used. The inks selected were reproduced and characterised through a multi-analytical approach. Quantification was performed by HPLC–DAD (high performance liquid chromatography with diode array detectors in the UV–VIS), showing that gallic acid is a minor compound in the gall extracts prepared following al-Qalalūsī instructions. In all the recipes, the higher concentration compounds in the gall extracts are the gallotannins pentagalloylglucose and hexagalloylglucose, ranging from 79 to 50% of the phenolic compounds. This supports the results of Raman and infrared spectroscopies. A comparison with medieval Iberian recipes was also done, which served to reinforce our previous results that show water as the sole solvent extracts with much lower yields than mixed solvents (water plus white wine or vinegar). publishersversion published

Medieval texts describe the use of the three-tone system as a pictorial procedure characteristic of Romanesque art to represent shape and volume. Some Medieval art treatises provide detailed instructions of its application, using specific names for each of the carnation colours: membrana (mid-tone or base colour), rosa and posc (darker) and lumen (lighter). In this study we have verified its use and application by analysing the mural paintings of the central apse of the church of Sant Climent de Taüll (Catalonia), currently on display at the Museu Nacional d'Art de Catalunya. A combination of microanalytical techniques, micro-infrared spectroscopy (µFTIR), synchrotron-based micro-X-ray diffraction (µSR-XRD), Scanning Electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Optical microscopy (OM), provided precise information on the composition and distribution of the compounds in the sequence of micrometric layers. We have identified the use of up to eight different pigments carefully mixed, to obtain a variety of tones in accordance to the recipes given in the Theophilus’ De diversis Artibus and the Hermeneia (Byzantine pictorial tradition). The inner layers, painted directly on the still wet lime mortar, show the typical carbonation microstructure of fresco, while the surface layers for the contours of geometric decorative elements and figures which required longer working times, were applied al secco. This work was financially supported by MINECO (Spain, PID2019–105823RB-I00) and Generalitat de Catalunya (2021 SGR 00343). µSR-XRD experiments were performed at BL13-XALOC beamline at ALBA Synchrotron in collaboration with its staff. We thank Museu Nacional d'Art de Catalunya MNAC and the cooperation of conservators and curators, especially Mireia Mestre and Paz Marquès.

Many enzymes possess high catalytic efficiency and selectivity that far surpass classical organic or organometallic catalysts. However, the initial starting enzyme for a given transformation does not always possess the right properties needed for broad utilization. Searching in genome/protein sequence libraries for homologs, aided with powerful bioinformatic tools developed in recent years, provides an avenue to identify superior biocatalysts. Herein, we highlight several case studies to illustrate the power of this concept. A brief discussion on its complementarity with contemporary approaches in protein engineering (such as directed evolution) and possible future developments is also provided.

Biopolymer-scaffold modification is widely used to enhance enzyme catalysis. A central challenge is predicting the effects of scaffold position on enzyme properties. Here, we use a computational-experimental approach to develop a model for the effects of DNA scaffold position on enzyme kinetics. Using phosphotriesterase modified with a 20bp dsDNA, we demonstrate that conjugation position is as important as the scaffold's chemistry and structure. Multiscale simulations predict the effective substrate concentration increases close to the scaffold, which has μM-strength binding to the substrate. Kinetic analysis shows that the effective concentration that the scaffold provides is best utilized when positioned next to, but not blocking, the active site. At ~5Å distance between scaffold and active site a 7-fold increase in

Although significant advances have been witnessed in the application of nanozymes in recent years, exploring new strategies to enhance the enzyme-like activity of nanozymes is of urgent importance. Herein, we investigate the feasibility of accelerating the peroxidase-like reaction rate of CuO nanostructures through Fe doping. The coprecipitation method was used to synthesize Fe-doped CuO (Fe-CuO) nanozymes, and the results indicate that the diversified valence of Fe benefits the redox reaction driven by CuO-based nanozymes. With the improved peroxidase-like activity, the Fe-CuO nanozyme enables the significant chromogenic oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB), facilitating the construction of a visual sensing platform for the sensitive and selective determination of ascorbic acid. Under optimal conditions, the absorbance at 652 nm decreases linearly with the concentration of ascorbic acid in the range of 5–50 μM, with a limit of detection as low as 4.66 μM. This work exemplifies the activity enhancement for peroxidase-mimicking nanozymes with a metal-doping strategy and provides a broad prospect for the design of more high-performance nanozymes for biosensing applications.

Copper(II) clusters of the type [CuII4OCl6L4] (L = ligand or solvent) are a well-studied example of inverse coordination compounds. In the past, they have been studied because of their structural, magnetic, and spectroscopic features. They have long been believed to be redox-inactive compounds, but recent findings indicate a complex chemical equilibrium with diverse mononuclear as well as multinuclear copper(I) and copper(II) compounds. Furthermore, depending on the ligand system, such cluster compounds have proven to be versatile catalysts, e.g., in the oxidation of cyclohexane to adipic acid. This report covers a systematic study of the formation of [CuII4OCl6(TPP)4] and [CuII4OCl6(TPPO)4] (TPP = triphenylphosphine, PPh3; TPPO = triphenylphosphine oxide, O=PPh3) as well as the redox equilibrium of these compounds with mononuclear copper(I) and copper(II) complexes such as [CuIICl2(TPPO)2], [{CuIICl2}2(TPPO)2], [{CuIICl2}3(TPPO)2], [{CuII4Cl4}(TPP)4], and [CuICl(TPP)n] (n = 1–3).

Radical translocation reactions are finding various uses in organic synthesis, in particular the stereospecific formation of complex natural products. In this work, the syntheses and single-crystal structures of two substituted 2-iodo-phenyl methyl-amides are reported, namely cyclo-propane carboxylic acid (2-iodo-phenyl)-methyl-amide, C11H12INO (1), and cyclo-heptane carboxylic acid (2-iodo-phenyl)-methyl-amide, C15H20INO (2). In each case, the methyl-amide group has a syn conformation, and this grouping is perpendicular to the plane of the benzene ring: these solid-state conformations appear to be well setup to allow an intramolecular hydrogen atom transfer to take place as part of a radical translocation reaction. Short intermolecular I⋯O halogen bonds occur in each crystal structure, leading to [010] chains in 1 [I⋯O = 3.012 (2) Å] and isolated dimers in 2 [I⋯O = 3.024 (4) and 3.057 (4) Å]. The intermolecular interactions are further quantified by Hirshfeld surface analyses.