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Hydrological factors are known to contribute to regulate the DOC balance at the reach scale. Interannual, intra-annual (seasonal) and event-based hydrological variability, particularly in headwater streams, affects stream-hillslope organic matter exchanges and river network connectivity, leading to significant space and time variations in sources and processes regulating DOC dynamics.This paper contributes to the ongoing effort to improve understanding of the related dynamics of streamflow and DOC concentration spatial variability across different timescales. Our investigation focused on a Mediterranean headwater catchment (Turbolo River, southern Italy) characterized by dry and hot summer climate enhancing network intermittency. The catchment was equipped with two multi-parameter sondes providing more than two-year (May 2019 to November 2021) continuous high-frequency measurements of several DOC-related parameters (fluorescent dissolved organic matter - fDOM, streamwater temperature and turbidity). The sondes were installed in two nested sections. The upstream sonde was located in a quasi-pristine sub-catchment, while the downstream sonde was placed at the Fitterizzi outlet, where some anthropogenic disturbances on water quality could be observed. Furthermore, streamflow data were acquired at both sites, while weather parameters were monitored at the catchment outlet. DOC estimates were achieved by correcting the fDOM values through an original procedure that did not require extensive laboratory measurements. Then, DOC dynamics at the seasonal and storm event scales were analyzed for both sites.At the seasonal scale, results confirmed the climate control on DOC production, with background concentrations that increased in hot and dry summer months. The hydrological regulation proved crucial for DOC mobilization and export, with the top 10th percentile of discharge being associated with up to 79% of the total DOC yield. The analysis at the storm scale examined 19 events per site using flushing and hysteresis indices. Our results highlighted substantial differences between the two catchments. In the steeper upstream catchment, the limited capability of preserving hydraulic connection in time with DOC sources determined the prevalence of transport as the limiting factor to DOC export. Downstream, transport- and source-limited processes were observed almost equally. The correlation between the hysteretic behaviour and antecedent precipitation was not linear since the process turned to be transport-limited for high accumulated rainfall values. Overall, the study demonstrated the importance of high-resolution measurements to explain DOC dynamics at multiple time scales with a quantitative approach.

This study investigates the spatial and temporal dynamics of DOC concentration in a Mediterranean headwater catchment (Turbolo River catchment, southern Italy) equipped with two multi-parameter sondes providing more than two-year (May 2019 to November 2021) continuous high-frequency measurements of several DOC-related parameters. The sondes were installed in two nested sections, a quasi-pristine upstream sub-catchment and a downstream outlet with some anthropogenic disturbances on water quality. DOC estimates were achieved by correcting the fluorescent dissolved organic matter - fDOM - values through an original procedure not requiring extensive laboratory measurements. Then, DOC dynamics at the seasonal and storm event scales were analyzed. At the seasonal scale, results confirmed the climate control on DOC production, with increasing background concentrations in hot and dry summer months. The hydrological regulation proved crucial for DOC mobilization and export, with the top 10th percentile of discharge associated with up to 79% of the total DOC yield. The analysis at the storm scale using flushing and hysteresis indices highlighted substantial differences between the two catchments. In the steeper upstream catchment, the limited capability of preserving hydraulic connection in time with DOC sources determined the prevalence of transport as the limiting factor to DOC export. Downstream, transport- and source-limited processes were observed almost equally. The correlation between the hysteretic behaviour and antecedent precipitation was not linear since the process reverted to transport-limited for high accumulated rainfall values. The study demonstrated the importance of high-resolution measurements to explain DOC dynamics at multiple time scales using a quantitative approach.

Biocompatible Pickering emulsions (PE) stabilized by tailor-made antioxidant-loaded particles have been known for some time now, but antioxidant-rich natural plant particle-based emulsions are much less well known. This study aimed to investigate the physico-chemical properties of commercial Zingiber officinale powders obtained from biological and conventional agricultural practice and ginger powder-based PE.The physico-chemical and biological properties of Zingiber officinale powders (GDPs) obtained from conventional (GDPC1 and GDPC2) and biological agricultural (GDPBIO) practices, and the properties of derived PE (PE_GDPs) were examined. All GDPs showed weak aggregation in aqueous media and a sufficiently hydrophobic surface to stabilize oil-in-water (O/W) PE against coalescence for at least 1 month. Zingiber officinale powders (2% w/w) derived from biological agricultural practices (GDPBIO) demonstrated the best emulsifying properties. The Zingiber officinale powders and PE_GDPs were also characterized by their phytochemical profiles. All the investigated samples exhibited ferric reducing ability power greater than the positive control, butylated hydroxytoluene (BHT), with values ranging from 91.21 to 102.63 μmol LThe results suggest that ginger powder should be used as a starting point to design biocompatible PEs for different applications in the functional food, nutraceutical, and pharmaceutical industries. In fact, powder and based PE are characterized by a promising antioxidant activity, carbohydrate hydrolyzing enzyme and lipase inhibitory properties. Further in vivo studies are necessary to confirm these findings. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John WileySons Ltd on behalf of Society of Chemical Industry.

Inland waters can be interpreted as “active pipelines” in which the complex dissolved organic carbon (DOC) dynamics occur, eventually contributing to negative net ecosystem production. Hydrological factors highly contribute to the DOC balance at the reach scale. Seasonal and event-based hydrological variability, particularly in headwater streams, affects both stream-hillslope organic matter exchanges and overall fluvial network connectivity, leading to significant space and time changes in sources and processes regulating DOC. Technological advances allow fine and continuous time scale measurements of several physicochemical parameters with optical aquatic sensors, providing great potential for a better understanding of aquatic ecosystems functioning.This study investigates the spatial and temporal dynamics of DOC concentration in a Mediterranean headwater catchment (Turbolo River catchment, southern Italy) equipped with two multiparameter sondes providing approximately 2.5 years (May 2019 to January 2022) of continuous high-frequency measurements of several chemical-physical variables, among which DOC-related parameters (fluorescent dissolved organic matter - fDOM, streamwater temperature and turbidity) at two different outlets. One sonde was installed in a quasi-pristine sub-catchment, while the other at the catchment outlet, characterized by some anthropogenic disturbances.The specific features of the upslope sub-catchments were considered to address the connection between seasonal and hydrologic dynamics and DOC changes. Continuous observations were supported by meteo-hydrological observations and discrete monitoring carried out in the period January-April 2021 when 59 samples were collected on-field and analysed in the laboratory to achieve reference DOC values, used for an original correction method of measured fDOM values.Results concern both the seasonal variability of background values and hydrological regulation of DOC export. Specifically, applying a Principal Component Analysis multivariate approach to the background values, seasonal clusters emerged with a clear temporal trajectory, highlighting similarities and differences among DOC and other measured parameters. Furthermore, DOC concentrations were positively correlated with discharge and even more with antecedent precipitation, reflecting the flushing effect of intense and prolonged precipitation. In both sites, the accumulated export of DOC for discharge values below the flow equalled or exceeded for 10% of the time (Q10) was lower than 35% of the total. Also, some differences in DOC concentration emerged between the two sites, with increased values with high flows in the catchment more affected by disturbances.High-frequency monitoring proved to be a valuable tool to explain DOC dynamics at multiple time scales with a quantitative approach, highlighting the climate control and the hydrological regulation on DOC production and export.

Electrofluorochromic devices (EFCDs) that allow the modulation of the light emitted by electroactive fluorophores are very attractive in the research field of optoelectronics. Here, the electrofluorochromic behaviour of a series of squaraine dyes was studied for the first time. In solutions, all compounds are photoluminescent with maxima located in the range 665–690 nm, characterized by quantum yields ranging from 30% to 4.1%. Squaraines were incorporated in a polymer gel used as an active layer in all-in-one gel switchable EFCDs. An aggregation induced quenching occurs in the gel phase, causing a significant decrease in the emission quantum yield in the device. However, the squaraines containing the thieno groups (thienosquaraines, TSQs) show a panchromatic emission and their electrofluorochromism allows the tuning of the fluorescence intensity from 500 nm to the near infrared. Indeed, the application of a potential difference to the device induces a reversible quenching of their emission that is significantly higher and occurs at shorter switching times for TSQs-based devices compared to the reference squaraine dye (DIBSQ). Interestingly, the TSQs fluorescence spectral profile becomes more structured under voltage, and this could be explained by the shift of the aggregates/monomer equilibrium toward the monomeric species, due to electrochemical oxidation, which causes the disassembling of aggregates. This effect may be used to modulate the colour of the fluorescence light emitted by a device and paves the way for conceiving new electrofluorochromic materials based on this mechanism.

In this work, the solubility of vanillic, gallic, syringic, p-coumaric, ferulic and caffeic acids was determined at 37 °C under different conditions, namely pure water and two different ionic media, NaCl(aq) and NaClO4(aq), at different ionic strengths (i.e., 0.16, 0.50, 1.0, 2.0 and 3.0 M). The solubility in water of all the acids was found to be higher than that in both of the ionic media. Moreover, the solubility of hydroxycinnamic acids was lower than that of hydroxybenzoic acids. The activity coefficients of neutral species were calculated from these data, this knowledge is necessary when modeling the dependence of equilibrium constants on the ionic strength. Results obtained in this work can be useful for further studies regarding complex formation equilibria between these ligands and bioavailable metal cations.

Fabrics obtained from cellulose spinning, extracted from Spanish broom, were coated with TiO2 film, through the low pressure plasma sputtering technique, in order to get antibacterial activity. The obtained fabrics were used for the photocatalytic degradation of Escherichia coli, by irradiation with UV-light emitting diodes (UV-LED), in a batch photocatalytic reactor. Before and after functionalization treatments, cellulosic substrates were chemically characterized by X-ray photoelectron spectroscopy (XPS) analyses. Water Contact Angle (WCA) measurements allowed obtaining information about the hydrophilicity of the materials, while their antibacterial efficiency was determined at several initial concentrations (from 103 up to 108 CFU mL−1) of bacteria in distilled water, bottled water and synthetic wastewater. It was found that photocatalytic reactions were capable of achieving up to 100% bacterial inactivation in 1 h of treatment, following a pseudo-first order kinetic model. No bacterial regrowth was observed after photocatalytic treatments in almost all experimental conditions. In contrast, during photolytic treatment (i.e. in the absence of the TiO2 coated fabrics) bacteria recovered their initial concentration after 3 h in the dark. Finally, the reusability of the plasma modified fibers to inactivate bacteria was studied.

This work reports the first example of effective purification, at laboratory level, of water polluted by petroleum hydrocarbons, by means of low pressure plasma fluorine grafted cellulose fiber extracted from Spanish Broom. In order to improve the affinity of the cellulosic surface towards water dispersed hydrocarbons, its original hydrophilic character was turned to super-hydrophobic, by a fluorine functionalization. Batch experiments were performed with the aim of studying kinetic and thermodynamic aspects of the adsorption process, as a function of the initial total hydrocarbon load and of the adsorbent amount. The kinetics data showed that the fiber removal efficiency ranged between 80–90% after one minute of contact time, in dependence of the initial hydrocarbon/fiber weight ratio (20–240 mg/g). A maximum adsorption capacity larger than 270 mg/g was estimated by fitting the adsorption isotherm measurements with the Langmuir model. It turned out that the functionalized fiber is capable to perform a significant hydrocarbons removal action if compared to other cellulosic materials reported in the literature. Finally, the efficiency of the plasma modified cellulose fiber, after iterative re-uses, was studied.

Fluorescent light modulation by small electric potentials has gained huge interest in the past few years. This phenomenon, called electrofluorochromism, is of the utmost importance for applications in optoelectronic devices. Huge efforts are being addressed to developing electrofluorochromic systems with improved performances. One of the most critical issue is their low cyclability, which hampers their widespread use. It mostly depends on the intrinsic reversibility of the electroactive/fluorophore molecular system and on device architecture. Here we show a novel fluorene-based mixed-valence electrofluorochromic system that allows direct electrofluorochromic switching and exhibits incomparable electrochemical reversibility and device cyclability of more than 10 000 cycles.

Long cellulose fiber (10–30 cm), extracted from Spartium junceum, was chemically treated with different softening agents with the aim to improve its textile applicability. A preliminary sensory evaluation of the treated fibers revealed an evident, though qualitative, improvement of the fiber softness. The effects of the softening agents on the fiber was evaluated quantitatively, by means of macroscopic measurements of the wettability, viscoelasticity, and thermal (thermal gravimetry) properties. Moreover, the effects of the softening treatments on the microscopic structure of the fiber and on its properties at a molecular level, were studied by optical and scanning electron microscope and X-ray diffraction (XRD), respectively. The macroscopic analysis showed that the softeners used increases the hydrophilicity and water wettability of the cellulose fiber with respect to the raw one. Moreover, the dynamical mechanical analysis on sample yarns showed that the softeners increase the interfiber frictional forces. A linear correlation between the interfiber friction and the increase of hydrophilicity and fiber wettability was shown. The treated fiber exhibits a more homogeneous thermal behaviour, due to more homogeneous structural features, since the thermal-induced cellulose fibrils depolimerization undergoes a marked temperature range contraction. These data can be well related with those obtained by microscopy analysis, showing that the fiber surface, after the treatment, appears thinner and less rough, as well as with the XRD analysis, which shows that softeners induce a significant decrease of the fiber crystallinity.

Thermotropic ionic liquid crystals are considered very promising functional electrolytes in DSSCs, batteries, fuel cells and capacitors1,2 for their unique combination of anisotropic ion conductivity and high polarizability.3 Moreover, they are interesting in the optoelectronic field as electrooptical functional unit.3-5 Many efforts have been devoted to the design of liquid crystals salts based on the viologen unit as organic cation, due to their interesting electrochromic and electrochemical properties.6 Most of the reported structures contain flexible chains directly linked to the nitrogens of the bipyridine rings.6 Their thermotropic behavior depends on the nature of the anion and of the N-substituents. A suitable choice of the latter makes access to different molecular orbital energy levels allowing different colors of the corresponding radical cation. N-Aryl substituted viologens, are of great interest because they show green colored radical cations due to the delocalization of the radical-cation over an extended p-system.7. Herein, we present a series of new N-aryl substituted liquid-crystalline viologens based on mono(4-alkylphenyl) and bis(4-alkylphenyl) bipyridinium cations with the same counterion but different alkyl chains (n=8, 10,12, 14), reporting their thermal behavior, their mesomorphic properties as a function of the chain length and their electrochromic properties in solution and in the LC phase.7 References: [1] Pan, X.; Wang, M.; Fang, X.Q.; Zhang, C.N.; Huo, Z.P.; Dai, S.Y.; Sci. China: Chem., 2013, 56, 1463–1469. [2] Sasi, R.; Chandrasekhar, B.; Kalaiselvi, N.; Devaki, S.J.; Adv. Sustainable Syst., 2017, 1, 1600031. [3] Axenov, K.V., Laschat, S.; Materials, 2011, 4, 206. [4] Bhowmik, P.K.; Kareem, M.; Al-Karawi, M.K.M.; Killarney S.T.; Dizon, E.J.; Chang, A.; Kim, J.; Chen, S.L.; Principe, R.C.G.; Ho, A.; Han, H.; Mandal, H.D.; Cortez, R.G.; Gutierrez, B.; Mendez, K.; Sharpnack, L.; Agra-Kooijman, D. M.; Fisch, M.R.; Kumar, S.; Molecules 2020, 25(10), 2435. [5] K. Goossen, K. Lava, C. W. Bielewski, K. Binnemans, Chem. Rev., 2016, 116, 4643. [6] Monk, P.M.S., The viologens: physico-chemical properties, synthesis and application of the salt of 4,40-bipyridine, John Wiley and Sons, Inc., Wiley – VCH, New York, Weinheim, 1998. [7] Veltri, L.; Cavallo, G.; Beneduci, A.; Metrangolo, P.; Corrente, G.A.; Ursini, M.; Romeo, R.; Terraneo, G.; Gabriele, B.; New J. Chem., 2019, 43, 18285-18293.

The simultaneous transformation of crystalline or amorphous cellulose into a furan-based bio-oil and cellulose citrate was realized avoiding the use of strong inorganic acids, drastic conditions, enzymatic treatments or microorganism fermentation. This innovative method is very eco-friendly and involves the use of molten citric acid under solvent free conditions at atmospheric pressure. An accurate discussion on chemical composition of the bio-oil enriched in bioprivileged molecules as well as structural and morphological characterization of cellulose citrate was reported. Moreover, mechanistic hypotheses were formulated on the basis of experimental findings and detailed DFT quantum-mechanical simulations were carried out to confirm, step by step, the proposed reaction paths.

A series of biarylaminofluorene-based systems with donor-π-donor (D-π-D) structure have been designed and synthesized in order to study the dependence on the π-conjugated bridge length of the intervalence charge-transfer transitions (IV-CT) and of the electronic coupling between the redox centers. To this purpose cyclic voltammetry, UV/Vis-NIR, fluorescence spectroscopy and computational investigations have been carried out to characterize the electronic structure of the compounds in the neutral as well as in the mono- and dication states. Additionally, a study of related D-π compounds has been performed to elucidate the effect of the interaction between two redox centers. Interestingly it was observed that the mono- and dication species exhibit intense transition bands in the NIR region, in the 10000-15000 cm−1 range, whose intensity depends on the oxidation state and thus it can be reversibly tuned by an applied potential. In a similar way, all compounds show an oxidation state dependent fluorescence which leads to electrofluorochromism. Particularly significant is the mixed valence behavior that provides these systems singular optoelectronic properties, making them excellent active components for electrochromic and electrofluorochromic applications.

Introduction: Renal dysfunction is a frequent complication in patients suffering from β-thalassemia major (β-TM). The aim of this study was to analyze the renal function and urine metabolomic profile of β-TM patients undergoing transfusions and deferasirox (DFX) therapy, in order to better characterize and shed light on the pathogenesis of renal disease in this setting. Methods and Subjects: 40 patients affected by β-TM treated with DFX and 35 age- and gender-matched healthy controls were enrolled in the study. Renal function was assessed. Glomerular filtration rate (GFR) was estimated with CKD-EPI and Schwartz formula for adults and children, respectively. Renal tubular function and maximal urine concentration ability were tested. Urine specimens were analyzed by nuclear magnetic resonance spectroscopy to identify the urinary metabolite profiles. Results: The study of renal function in β-TM patients revealed normal estimated (e)GFR mean values and the albumin-to-creatinine ratio was Discussion: The major finding of this work is that β-TM patients and controls exhibit different concentrations of some metabolites in the urine. Early recognition of urinary abnormalities may be useful to detect and prevent kidney damage.

Porous carbon materials are currently subjected to strong research efforts mainly due to their excellent performances in energy storage devices. A sustainable process to obtain them is hydrothermal carbonization (HTC), in which the decomposition of biomass precursors generates solid products called hydrochars, together with liquid and gaseous products. Hydrochars have a high C content and are rich with oxygen-containing functional groups, which is important for subsequent activation. Orange pomace and orange peels are considered wastes and then have been investigated as possible feedstocks for hydrochars production. On the contrary, orange juice was treated by HTC only to obtain carbon quantum dots. In the present study, pure orange juice was hydrothermally carbonized and the resulting hydrochar was filtered and washed, and graphitized/activated by KOH in nitrogen atmosphere at 800 &deg, C. The resulting material was studied by transmission and scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption isotherms. We found porous microspheres with some degree of graphitization and high nitrogen content, a specific surface of 1725 m2/g, and a pore size distribution that make them good candidates for supercapacitor electrodes.

Functional electrochromic materials that allow energy modulation both in the visible and in the near-infrared (NIR) spectral ranges are attracting increasing interest both for the fundamental scientific aspects related to their spectroelectrochemistry and for their technological applications. Vis-NIR dimmable windows based on these materials are very promising for tunable shading, thus allowing lighting and heat energy use saving. Organic mixed valence compounds (MVs) are an interesting class of small molecules with NIR electrochromism arising from optically induced intervalence charge transfer transitions (IVCT). Here, we report the synthesis and vis-NIR electrochromic properties of new organic mixed valence systems, with two and three amino redox centers bridged by a dibenzofulvene (DBF) unit. We studied the neutral and charged state characteristics of these MVs in solution by spectroelectrochemical experiments, theoretical TD-DFT investigations, and, in the solid state, through electrochromic devices (...

In this paper, we present a new type of parallax barrier, for switchable 2D/3D display vision, obtained by using a Reverse Mode Polymer Dispersed Liquid Crystal display (RV-PDLC). The parallax barr...

Here we have studied the complexation of coumarin-3-carboxylic acid with Al(III) and Fe(III) at 37 °C and in 0.16 mol L−1 NaCl. The protonation constant of coumarin-3-carboxylic acid was determined in order to evaluate the competition of the ligand for the metal cations and H+. Speciation profiles obtained by potentiometric titrations and supported by UV and 1H- and 13C-NMR data show that a complexation occurs at a ligand-to-Al(III) ratio of 1 : 1 and at a ligand-to-Fe(III) ratio of 1 : 2. These data were supported by a computational evaluation, which highlighted the different structural behaviour of the two metals in the complexes. Indeed, the Al(III) cation forms bidentate complexes involving a 6-membered ring by binding both the carboxyl oxygens of the ligand. In contrast, the Fe(III) ion preferentially forms monodentate tetrahedral complexes on the carboxylate moiety of the HCCA ligand.

Electrochemical measurement of pH on paper artifacts is a very important tool to assess the state of paper conservation. Different methods using different types of electrodes have been standardized to provide reproducible pH values of paper. One of these methodologies is not very invasive since it is made on the paper surface by means of a surface electrode in contact with the paper through a small layer of water previously added at the measurement point. This method is very convenient but suffers from the fact that the pH value given by the instrument is continuously changing during the measurement with a very fast rate in the first seconds and tending to reach a plateau value after very long time. Usually, the measure is taken at a time after which the rate of pH change is below a given value, i.e., when the value can be considered constant. This condition is usually signaled by an automatic instrumental alert provided to the operator. This pH value, however, is not the asymptotic one, which can be reac...

Wood artefacts are subject to damage by biologic infestations due to bacteria, insects, and fungal species. One of the worst feared attacks is due to the xylophagous insects whose larvae feed on wood by boring galleries, at the expense of building timbers and worked woods. These beetles are responsible for daily destruction of the world’s wooden cultural heritage, and their elimination has been always a big problem for conservation of wood. The need to avoid the use of chemical methods in conservation for pest control has led to the development of various non-chemical, non-toxic treatments. Among these, heating with microwaves (MW) seems to be one of the most promising, since it has already shown its high efficacy in destroying pests. Insect-infested wood remediation by MW heating in conservation is based on the larger thermal increment induced in larvae than in wood, due to their different dielectric permittivity in the GHz frequency range. However, the side effects that may occur due to MW heati...

Polymer-dispersed liquid crystals (PDLCs) are composite materials formed by micron-sized droplets of liquid crystals (LCs) dispersed in a polymer matrix, which can be turned from an opaque state to...

Here we have studied the complexation of caffeic, ferulic and p-coumaric acids with Al(III) under physiological conditions (i.e. at 37 °C and in 0.16 M NaCl). Solubility and protonation constants of these hydroxycinnamic acids were firstly determined in order to evaluate the competition of the ligands for the Al(III) and H+ ions. Speciation analysis made by potentiometric titrations and supported by UV and 1H-NMR data shows that a pH-dependent complexation occurs at 1 : 1 and 2 : 1 ligand-to-Al(III) ratios. Notably, these data combined with computational (DFT) results unequivocally indicate that the complexation site is the carboxylate group of the ligands thus excluding any involvement of the phenolic sites.

Herein we present organic mixed-valence compounds with an innovative H-shape design, where four redox centres are bridged "vertically" via a dibenzofulvene backbone and "horizontally" via a bis-(dibenzofulvene)-thiophene bridge. These compounds are easily oxidized to stable highly charged radical species which show intense intervalence charge transfer transitions in the near infrared region. Interestingly, depending on the position of the arylamine substituents on the bridge, both vertical and horizontal electron transfer pathways can be optically induced.

Fabrics obtained from cellulose spinning, extracted from Spanish broom, were coated with TiO

Two different sets of ionic liquid crystals based on bistriflimide salts of non-symmetrically substituted polyfluorinated bipyridinium (viologens) and bent symmetrically substituted dialkyl-oxadiazolyl-bipyridinium have been synthesized, in order to study the effect on the mesomorphic and electrooptical properties of the non-symmetric functionalization (alkyl chain and fluoroalkyl chains of different lengths) on the two pyridinium rings and additionally the effect of a bent conjugated spacer among the two pyridinium units of the viologen. POM and DSC characterization show that the synthesized salts have a mesomorphic and, in some cases, polymesomorphic behaviour in a wide thermal range, also encompassing room temperature. Some of the compounds exhibit an SmA phase in addition to more ordered smectic phases at lower temperature. The presence of a fluorinated chain on one side seems to generally increase the stability of the SmA phase of the ionic liquid crystal compared to alkylated analogues of viologens. Moreover, the insertion of the bent oxadiazolyl spacer between the two pyridinium units, has a significant effect on the mesophase behaviour leading to dendritic textures recalling that of banana phases. Electrochemical characterization by cyclic voltammetry shows that the presence of a fluorinated moiety causes an easier reduction compared to typical alkyl viologens while the oxadiazolyl-bipyridinium derivatives have more negative reduction potentials. Spectroelectrochemical experiments show that in contrast to classic viologens showing a typical electrochromic band of their radical cation, the oxadiazolyl insertion between the two pyridinium moieties hampers electrochromism due to absence of resonance coupling between the N redox centers. Interestingly, electrochromism of the polyfluorinated viologens, besides being observed in solution is observed in the ionic liquid crystal smectic phase of some of the salts of this series, upon radical cation formation the spectrum exhibits a further electrochromic band in the near infrared range which is not observed in solution.

Novel 1,1′-bis(4-alkylphenyl)-[4,4′-bipyridine]-1,1′-diium salts, with alkyl chains of different lengths (8, 10 and 14 carbon atoms) and with different counteranions (Cl-, NTf2-, OTf-, OTs-, PF6-, BPh4-), have been prepared and fully characterized for their thermotropic behavior by polarized optical microscopy (POM), and calorimetric measurements. Almost all the synthesized compounds showed a high thermal stability, a wide temperature range of liquid-crystalline mesophase and, for some of them, the LC transition temperatures were relatively low. These compounds also exhibited electrochromic properties, which have been studied both in solution and in the LC phase, making the new materials very interesting for different opto-electronic applications.

This chapter discusses some recent developments of liquid crystal science in the field of electrochromic and electrofluorochromic materials. Liquid crystals are a condensed state of molecules which exhibit some properties of the solid state and some properties of the liquid state, thus combining order and dynamics. These properties can be advantageously used to develop new advanced functional materials which combine and integrate different properties. Specifically, here we show that the integration of the mesomorphic behavior with key functionalities such redox-active, electronic charge mobility, ion conductivity, and photoluminescence is a very promising approach for the design of electrochromic and electrofluorochromic materials able to work in single layer devices in the bulk liquid crystalline phase.

This review focuses on the ability of some natural antioxidant molecules (i.e., hydroxycinnamic acids, coumarin-3-carboxylic acid, quercetin, luteolin and curcumin) to form Al(III)- and Fe(III)-complexes with the aim of evaluating the coordination properties from a combined experimental and theoretical point of view. Despite the contributions of previous studies on the chemical properties and biological activity of these metal complexes involving such natural antioxidants, further detailed relationships between the structure and properties are still required. In this context, the investigation on the coordination properties of Al(III) and Fe(III) toward these natural antioxidant molecules might deserve high interest to design water soluble molecule-based metal carriers that can improve the metal’s intake and/or its removal in living organisms.

In this work we have studied the complexation of quercetin (3,3′,4′,5,7-pentahydroxyflavone, H5Que) with aluminum(III), iron(III) and copper(II) at 37 °C and in aqueous solution (0.16 M NaCl). To evaluate the competition of the ligand for the metal cations and H+, the protonation constant of quercetin was also determined under the same experimental conditions. Speciation profiles obtained by potentiometric titrations and supported by UV–Vis data show that in aqueous solution a complexation occurs at 1:1 ligand-to-cations ratio for Al(III) and Cu(II), and at 1:1 and 1:2 ligand-to-Fe(III) ratio. The coordination sites of quercetin to the different metal ions were determined with the aid of 1H NMR and 13C NMR spectroscopy as well as by a computational approach. Synergies between experiment and computation show that aluminum and iron ions show no clear preference towards any of the complexation sites of quercetin, while for copper the 4,5 site (i.e., the 4‑carbonyl-5-hydroxyl site of the A and C rings of the ligand) could be excluded.

Thienosquaraines are an interesting class of electroactive dyes that are useful for applications in organic electronics. Herein, the redox chemistry and electrochromic response of a few newly synthesized thienosquaraines are presented. These properties are compared to those of the commercial 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine. The stability of the radical ions formed in electrochemical processes strongly affects these properties, as shown by cyclic voltammetry, in situ spectroelectrochemistry, and quantum chemical calculations. Furthermore, all of the dyes show aggregation tendency resulting in panchromatic absorption covering the whole UV/Vis spectral range.

The cleavage of the etheric C O bond in diphenyl ether (DPE), phenethyl phenyl ether (PPE) and benzyl-phenyl ether (BPE) has been investigated by using Ru/C (5% wt) and Pd/C (5% wt), as heterogeneous catalysts, under reaction conditions generally adopted for the reductive catalytic fractionalization of lignocellulosic biomasses (lignin-first approach). Catalytic tests were carried out in the presence of simple C1-C3 alcoholic H-donor solvents (methanol, ethanol and 2-propanol) used as such or in mixture with water in the temperature range of 120–240 °C both in the presence or in the absence of molecular hydrogen as reducing agent. Under transfer hydrogenolysis conditions, the Ru/C catalyst was found to be the best performing system in the cleavage of the 4–O–5 etheric C O bond (95 % DPE conversion in 2-propanol at 210 °C after 3 h of reaction) with a less pronounced tendency in hydrogenating the aromatic ring. Upon increasing the water content in the reaction medium, a decrease in the cleavage of the C O bond of DPE together with a higher production of phenolics is observed as a consequence of the reductive hydrolysis reaction occurrence. The best yield in aromatic compounds (52 %) was obtained by using as solvent a water/2-propanol (75:25, v/v) mixture in absence of added molecular hydrogen, with the alcoholic fraction being the in-situ H-source. A lower tendency to undergo to hydrolysis reaction together with a higher production of aromatics is registered in the case of phenethyl phenyl ether and benzyl-phenyl ether. Results are explained in terms of the higher steric hindrance of PPE and BPE with respect to DPE and of the competitive adsorption of arenes arising from hydrogenolysis of etheric β–O–4 and α–O–4 bonds (phenol + ethyl benzene or phenol + toluene) on the Ru/C catalyst surface.

Electrochromic devices (ECDs) that allow the modulation of light transmission are very attractive in the research field of energy saving. Here all-in-one gel switchable ECDs based on mixed-valence electroactive compounds were developed. The use of the thienoviologen/ferrocene couple as cathode and anode, respectively, leads to a significant electrochromic band in the visible range (550&ndash, 800 nm), with a color change from yellow to green, and to a lower band in the NIR region (1000&ndash, 1700 nm), due to the presence of one electroactive-chromic species. Replacement of the electroactive ferrocene with a fluorene-diarylamine electroactive-chromic species, allows to extend and intensify the absorption in the NIR region, thus affording modulation of the solar radiation from 500 up to 2200 nm. High optical contrast, fast coloration and bleaching times and outstanding coloration efficiencies were measured for all observed absorption bands upon the application of small potential differences (1.4 V &lt, DV &lt, 2 V).

BTX stands for Benzene, Toluene, and Xylenes, which are volatile organic compounds contained in petroleum products such as gasoline. They have negative health effects and are sadly known for soil, air, and water contamination. This paper provides an investigation on BTX removal from open water systems like those represented by natural water bodies. In such systems, the evaporation process takes place, stealing the pollutants from the aqueous matrix by transferring them into the air, resulting in a secondary pollution. To prevent this situation, adsorption of these organic compounds on cellulose fibers, extracted from Spanish Broom vegetable, was studied. Raw and surface modified cellulose fibers were used for this purpose. The second ones were hydrophobized by two different green and low-cost functionalization systems (no solvent urethane functionalization and low pressure plasma treatments). Batch experiments were performed in an open system where BTX underwent two competing removing mechanisms: volatilization, and adsorption/desorption on/from the fibers dispersed in the water system. A mathematical model was implemented for the interpretation of the observed time-varying pollutant concentrations and the estimation of the kinetic constants for adsorption, desorption, and evaporation. The developed model, provided with the aforementioned parameters calibrated for each type of fibers, was then used for the prediction of their adsorption capacities both into open and closed systems.