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Spectroscopy is a scientific topic at the interface between Chemistry and Physics, which is taught at high school level in relation with its fundamental applications in Analytical Chemistry. In the first part of the paper, the topic of spectroscopy is analyzed having in mind the well-known Johnstone's triangle of chemistry education, putting in evidence the way spectroscopy is usually taught at the three levels of chemical knowledge: macroscopic/phenomenological, sub-microscopic/molecular and symbolic ones. Among these three levels, following Johnstone's recommendations the macroscopic one is the most useful for high school students who learn spectroscopy for the first time. Starting from these premises, in the second part of the paper, we propose a didactic sequence which is inspired by the historical evolution of spectroscopic instruments from the first spectroscopes invented by Gustav Kirchhoff and Robert Bunsen in 1860 to the UV–vis spectrophotometers which became common since the 1960s. The idea behind our research is to analyze the conceptual advancements through the history of spectroscopy and to identify the key episodes/experiments and spectroscopic instruments. For each of them, a didactic activity, typically an experiment, is then proposed underlining the relevant aspects from the chemistry education point of view. The present paper is the occasion to reflect on the potentialities of an historical approach combined with a laboratorial one, and to discuss the role of historical instruments and related technological improvements to teach spectroscopy. [ABSTRACT FROM AUTHOR]

Nuclear Magnetic Resonance (NMR) relaxometry is widely used for food products characterization. In order to exploit the full potential of the relaxation methods one can look at magnetic field dependence of spin-lattice relaxation. Analysis of relaxation dispersion characteristics of food systems may complement knowledge about composition and dynamics of their constituents, in particular, of water. In this article, we review the basic principles as well as recent applications of field-cycling NMR relaxometry in different food systems. The inter- and intra-molecular interactions modulated by molecular dynamics can be efficiently studied with NMR relaxometry. This method can be exploited for discrimination of liquids, determination of diffusion coefficient or paramagnetic ion concentration, observation of crystallization/solidification processes. The technique has already proven to be helpful to investigate changes occurring in food products due to different processing techniques and to detect food adulteration. FFC benchtop instruments represent a new frontier in food studies. [Display omitted] • NMR relaxometry is a powerful tool to characterize food products. • Principle of field-variable relaxometry and key advantages over conventional relaxometry is presented. • This review comprises an overview of the large spectrum of food-related applications of field-variable NMR relaxometry. [ABSTRACT FROM AUTHOR]

Public engagement becomes increasingly important for scientists. One reason is the demand of the taxpayer to know what her or his money is being spent on, and why. The other one is that in a world that increasingly relies on technology, student engagement even at a very young age becomes a target to assure the needed supply of well-educated and especially motivated scientists for the decades to come. And it falls on the older generation of current researchers to leave the comfort of their lab once in a while, to awaken the interest for science among the population. Many people may know that there is a ‘liquid crystal’ in their mobile (cell) phone display, but when prompted, no one really knows what that liquid crystal actually is, let alone how the display they use many times every day, actually works in principle. It is part of our job to change this. In this contribution Valentina Domenici and Ingo Dierking would like to report on two recent Science Festival events in which they took part, one held in Genoa, Italy, and the other in Manchester, UK. [ABSTRACT FROM AUTHOR]

In this work, we report a first detailed study of the mesophasic behaviour of the calamitic liquid crystal, a (4,4′-bis(4″-carboxybelzyloxy)biphenyl derivate, labelled 9/2 RS/RS, showing an isotropic-isotropic-(columnar)-cubic phase behaviour on cooling.1H NMR diffusometry allowed to distinguish between the two isotropic phases in terms of diffusion characterized by different Arrhenius activation energy, while13C NMR static measurements and2H NMR investigations were of help in understanding the orientational ordering properties of the metastable columnar phase and confirmed the isotropic state of the sample in the cubic phase. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) is a spectroscopic technique widely used to investigate materials and soft matter in particular. In this brief review, the main uses of NMR techniques to investigate different aspects of liquid crystals, such as the orientational and dynamic properties, the supramolecular structure and average molecular conformations, are described. In the second part of the paper, the case study of a ‘de Vries’ liquid crystal is reported and the main results obtained by combining different NMR techniques are discussed. [ABSTRACT FROM AUTHOR]

Liquid crystals that exhibit de Vries smectic A phases are promising materials for new generations of ferroelectric liquid crystal displays and other electro-optical devices. We investigated the molecular dynamic properties of a rod-like de Vries liquid crystal compound, namely the 9HL, a (S)-hexyl lactate derivative, in the whole mesophasic range. This is the first molecular dynamics' investigation on a de Vries phase, and the interest of this system is related to the understanding of the structural and supramolecular organization of de Vries SmA phases, which has been a subject of a broad scientific debate in the last years. Proton NMR spin-lattice relaxation times, T1, were measured in the range 100 MHz to 5 kHz, thus covering a very wide range of motional regimes. 1H NMR dispersion curves and temperature-dependent relaxation rates were analyzed with a global minimum target fitting approach and the main molecular motions, namely reorientational diffusion, translational self-diffusion, layer undulation, and tilting director fluctuations were fully characterized. The molecular dynamics' behavior observed across the SmA-SmC* phase transitions of 9HL was consistent with the proposed cluster diffuse cone model for the de Vries SmA phase. [ABSTRACT FROM AUTHOR]

Recent results obtained by1H NMR relaxometry of liquid crystals having twist grain boundary (TGB) phases are here reviewed. In particular, three chiral rod-like lactate derivative mesogens were investigated. In the isotropic phase, three-exponential magnetization decay was observed in all cases and the three distinct spin-lattice relaxation times (T1) were assigned to three specific molecular groups of these molecules. In the TGBA* and TGBC* phases the magnetization decay is mono-exponential and the main features of the1H NMR dispersion curves analyzed through a global target fitting procedure in terms of specific molecular and collective dynamics are discussed. [ABSTRACT FROM AUTHOR]

This is a brief overview on recent studies on liquid crystalline elastomers (LCEs) based on polysiloxane chain, in the form of monodomain films, selectively 2H-labeled in different parts of the LCE samples, i.e. on the crosslinker or mesogenic units. 2H NMR spectroscopic techniques were used to measure the temperature dependence of the quadrupolar splittings, line widths and relaxation times, T1 and T2. From these data, several information about the orientational order parameter, S, of various LCE fragments, thermodynamic features of the isotropic-nematic transition and main motional processes could be generalized for this type of elastomers. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Recent progresses of NMR spectroscopy to the study of liquid crystals and related ordered systems are surveyed. Particular attention will be devoted to review suitably tailored NMR experiments and their applications on those systems (e.g. biaxial nematics, chiral smectics, V shaped mesogens, liquid crystalline elastomers) which are presently subject of active and innovative research. [Copyright &y& Elsevier]

New bilayered composite systems with tunable and temperature-dependent formation of periodical wrinkles on the surface are the object of this report. The samples were prepared by spin-coating deposition of a thin film of the conducting polymer poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on the surface of standard monodomain liquid crystal elastomer (LCE) films. Several bilayered materials were prepared by changing the thickness of PEDOT:PSS nanofilms. Basic characterization showed very good stability and adhesion between the two components also after performing multiple heat cycles around nematic-to-isotropic transition temperature of the LCE. Interestingly, formation of uniaxially aligned microwrinkles was observed, with most of the wrinkles aligned along perpendicular direction with respect to the nematic director, due to reversible elongation/compression of the LCE during thermal cycles. [ABSTRACT FROM PUBLISHER]

In this work, we present our recent results obtained in the field of translational self-diffusion studies by means of 1H NMR diffusometry in smectic phases formed by calamitic chiral liquid crystals. In particular, the diffusional behavior of chiral smectic phases with different clinicity, such as the ferroelectric and antiferroelectric phases, will be discussed on the basis of the results obtained on three different chiral smectogens. This research demonstrates that, despite previous assertions, out-of-plane translational diffusion in smectic phases is poorly affected by the clinicity of the phases, showing no discontinuity at the transition from synclinic to anticlinic structures, typical of the smectic C* phases. We can conclude that diffusion basically reflects the layered smectic structure where in-plane diffusion is much faster and less hindered than the out-of-plane one. [ABSTRACT FROM PUBLISHER]

In this paper, some of the most relevant 2H NMR experiments with the aim of determining the biaxial nature of the nematic phase in several thermotropic liquid crystals are overviewed. Advantages and disadvantages of the technique are discussed. This contribution is an extract of the lecture held in Erice (Sicily) in occasion of the “18th Course - Liquid crystal nanostructures and self-assembling: from organic electronics to metamaterials”, the 2nd School of the Italian Liquid Crystal Society. [ABSTRACT FROM AUTHOR]

Solid State 2H Nuclear Magnetic Resonance (NMR) spectroscopy was applied to the structural and orientational studies of a selectively labelled ‘de Vries’ liquid crystal compound. Measurements were performed at five values of the magnetic field, ranging from 4.70 to 18.80 T. The trend of the orientational order S and tilt angle θ of the 2H-labeled moiety in the SmA and SmC* phases at different magnetic fields confirms previous results and allows us to better characterize the SmA-SmC* transition. [ABSTRACT FROM PUBLISHER]

Abstract: For the first time new type of liquid single crystal elastomers forming the chiral smectic A* (SmA*) phase has been prepared using chiral lactic acid derivative as a co-monomer. The synthesis and the basic characterization of the ferroelectric liquid crystalline co-monomer based on differential scanning calorimetry and small/wide-angle X-ray scattering are reported and discussed. The monomer possesses the paraelectric SmA* and the ferroelectric SmC* phases over a broad temperature range. The preparation of new smectic liquid crystalline elastomers together with characterization of their mesomorphic and structural properties is also reported. New elastomers possess the orthogonal paraelectric SmA* phase over 50 K broad temperature range. [Copyright &y& Elsevier]

In this study, we report the preparation, structure characterization, and application of new MoO nanowires, promising candidates for lithium intercalation, hydrogen sensing, and smart windows due to their photochromic property. These nanowires are a mixture of MoO and conductive MoO phase and have been used to prepare composite films based on liquid single crystal elastomers (LSCE). The structure, morphology, and thermomechanic behavior of these films are discussed. In particular, we show that the particular combination of molybdenum-based nanowires and LSCEs allows for doping of liquid single crystal elastomers, preserving the pristine mechanical and optical properties of the host matrix. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this study, selectively deuterium-labelled monodomain liquid single crystalline elastomers have been investigated by means of 2H-NMR spectroscopy. The analysis of the spectral features as well as the study of the orientational properties in the paranematic and nematic phases confirmed the supercriticality of the paranematic-nematic transition as an intrinsic property of these systems. Moreover, the combined study of the spin-spin relaxation times (T2) and the 2H-NMR spectral linewidth measured in the paranematic phase indicates the presence of slow dynamic motions. [ABSTRACT FROM AUTHOR]

In this work an attempt is made to compare and rationalise the structural and dynamic behaviour of some ferroelectric rod-like mesogens studied by our group in recent years, mainly by means of 2H- and 13C-nuclear magnetic resonance (NMR) spectroscopy. This comparison concerning the local orientational order, the average molecular conformation and the chiral smectic C (SmC*) phase structure, with a brief overview on the reorientational dynamic properties, allowed us to identify some common behaviour of these ferroelectric rod-like mesogens when decreasing the temperature from lower ordered phases to and within the SmC* phase. The main results obtained by means of NMR studies on these mesogens are rationalised and discussed in comparison with detailed discrete Fourier transform computations of their molecular conformations (in the limit of isolated molecules) with the purpose of enlightening the role of intermolecular and packing interactions in the ferroelectric phase with respect to the smectic A and nematic phases. [ABSTRACT FROM AUTHOR]

Recently several liquid crystals having a chiral smectic C phase (SmC*) have been studied by means of NMR spectroscopy combined with ab initio calculations. The advantage of exploiting different experimental techiques, such as 2H and 13C NMR, and the possibility to calculate relevant spectroscopic quantities, such as 13C chemical shift tensors, by means of ab initio methods, is here discussed based on recent results obtained on several ferroelectric liquid crystal compounds. Orientational order parameters, conformational and structural features can be determined in a self consistent way by applying this combined approach. [ABSTRACT FROM AUTHOR]

Abstract: Photoactive materials based on azobenzene derivatives exhibit interesting properties related to the reversible photo-isomerisation between the trans and cis isomers of the azo-compound. In this work we report the preparation and physical–chemical characterization of Liquid Single Crystal Elastomers (LSCEs) containing azobenzene derivative side-chain mesogens as co-monomer. The interplay between the orientational ordering and mechanical response in the nematic phase is investigated by thermomechanical measurements as well as by deuteron NMR spectroscopy. We demonstrate that local nematic order can be reliably probed in azo-LSCEs using low molar mass deuterated cyanobiphenyl nematogen in low concentrations. No phase separation of the dopant is observed. The nematoelastic coupling between the effective sample deformation and average nematic order parameter is present over a wide temperature range even in the systems with relatively large heterogeneity of the nematic order and misaligned nematic domains. [Copyright &y& Elsevier]

Abstract: Recent studies based on NMR spectroscopy put in evidence the occurrence of a slow motion regime in bent-shaped liquid crystals having the aromatic core formed by five phenyl rings linked by ester groups both in the isotropic and in the nematic phases. In this paper a brief overview of these NMR studies is presented and additional new relaxation data recorded on a banana-shaped mesogen are reported and discussed. In particular, proton spin-lattice relaxation times, T 1, were acquired at different Larmor frequencies from 8 MHz to 5 kHz by means of NMR relaxometry in a wide range of temperatures from the isotropic to the crystalline phases. These data confirm that NMR relaxation in bent-core liquid crystals is affected by much slower dynamics than that observed in common rod-like liquid crystals and that overall molecular reorientations are responsible of this slow motion regime. This finding is discussed in the frame of the results obtained by means of several NMR methods, such as 2H NMR T 2 analysis and 1H self-diffusion NMR measurements, on the same bent-core molecule. [Copyright &y& Elsevier]

In this work the structure of the tilted TGBC* phase is investigated by means of the line-shape analysis of Deuterium NMR spectra. The case of a rod-like mesogen containing a (S)-2-methylbutyl-(S)-lactate unit in the chiral chain, whose acronym is HZL 7/*, is taken as a representative example for the large temperature range of stability of its tilted TGB* phases. By comparing the experimental and computed Deuterium NMR spectra several structural features can be extracted. For instance, the analysis of Deuterium NMR line-shapes put in evidence the occurrence of helical deformations due to the effect of the external magnetic field. [ABSTRACT FROM AUTHOR]

Several 2H NMR studies have been performed on two deuterium labelled banana-shaped liquid crystals, the 1,3-phenylene bis{4-4'-(11-undecenyloxy) benzoyloxy} benzoate (Pbis11BB) and its 4-chloro homologue (ClPbis11BB), in the isotropic, nematic and B2 phases.In this article, the state of the art of these studies is drawn and some new 2H NMR measurements on deuterated banana sub-units, namely the 3-(benzoyloxy)phenyl benzoate-d10 (BOB-d10) and its 4-chloro homologue (ClBOB-d10), used as small probes dissolved in two banana-shaped liquid crystals in the nematic phase are reported.As a general result, the orientational ordering properties of these sub-units are discussed in the frame of recent results obtained on the same banana-shaped liquid crystals dissolved in calamitic nematic solvents as well as in the bulk. [ABSTRACT FROM AUTHOR]

Experimental evidences of the slow dynamic behaviour of a banana-shaped liquid crystal (LC) detected by means of Deuterium Nuclear Magnetic Resonance (DNMR) in its nematic phase are reported. Deuterium line-shape and line-width trends of DNMR spectra of three selectively deuterium-labelled isotopomers of 4-chloro 1,3-phenylene bis 4-4′-(11-undecenyloxy) benzoyloxy benzoate (ClPbis11BB) are discussed in comparison with those of a deuterated probe dissolved in ClPbis11BB, used as LC solvent. Different dynamic regimes are observed for the central and lateral aromatic rings of the probe. These experimental remarks are discussed in terms of overall and internal molecular motions. [ABSTRACT FROM AUTHOR]

In this work the dynamic behaviour of the ferroelectric liquid crystal (‐)‐( S )‐[4‐(2‐methylbutyloxycarbonyl)phenyl] 4‐ n ‐heptylbiphenylcarboxylate (MBHB) in its smectic A (SmA), unwound chiral smectic C (uSmC*) and chiral smectic C (SmC*) phases has been studied by means of 2 H NMR spectroscopy. Zeeman ( T 1Z ) and quadrupolar ( T 1Q ) spin‐lattice relaxation times have been analysed to extract dynamic parameters (diffusion coefficients and activation energies). The small step rotation diffusion model in the uniaxial approximation has been used to describe overall spinning and tumbling motions, and the strong collision model to describe the internal reorientations of the aromatic fragment. Relaxation data in the SmC* phase have been analysed by using a theoretical approach. The dynamic features obtained in the smectic phases of this mesogen are here presented and discussed in comparison with the results obtained in other ferroelectric liquid crystals, focusing on the fast regime of motions. [ABSTRACT FROM AUTHOR]

The behaviour of the 2 H NMR line-width throughout the whole mesophasic range of the ferroelectric liquid crystal “1-methylheptyl 4'-(4?-n-decyloxybenzoyloxy) biphenyl-4-carboxylate” (10B1M7) is here reported and discussed. Static Fringe Field NMR Diffusometry measurements from the isotropic to the anticlinic phase have been performed leading to a significant result concerning the tumbling diffusional coefficient (D ? ). These results have been compared to X-Ray measurements and 2 H NMR line-widths in order to explain the peculiar behaviour occurring at the transition between the ferroelectric (FLC) and the antiferroelectric (AFLC) liquid crystalline phases. [ABSTRACT FROM AUTHOR]

Results of studies of 4,4′-di- n -heptylazoxybenzene (HAB) in the isotropic, nematic and smectic A phases are presented. Two experimental methods were employed: broad band dielectric spectroscopy and nuclear magnetic resonance spectroscopy. The complex dielectric permittivity, ε *( ω )=; ε ′( ω )-i ε ″( ω ), was measured in the frequency range 1 kHz-4 GHz. This allowed two main relaxation processes to be separated in all the phases studied: the low frequency (l. f.) process connected with molecular reorientations around the short axes, and the high frequency (h. f.) process connected with the rotations around the long axes. The corresponding relaxation times and activation enthalpies were obtained. The l. f. relaxation time changes step-wise at the phase transitions, whereas the h. f. relaxation time passes smoothly through all the phases. The measurement of 2 H spin-lattice relaxation times was carried out throughout the mesophase range at 61.38 MHz. These data were analysed together with the relaxation times measured at 10.00 and 46.04 MHz, available from previous studies. Using suitable theoretical models the principal components of the diffusional tensor, D || and D ⊥ , as well as the diffusion coefficients D R relative to the internal rotation of the phenyl rings, were determined. The results of both studies are compared and discussed. [ABSTRACT FROM AUTHOR]

A new approach to analyze 2H spin-lattice relaxation times in tilted smectic phases in terms of dynamic parameters for individual molecular and internal motions is reported. Such analysis, commonly applied to uniaxial phases, could not be extended so far to chiral smectic phases for both experimental and theoretical reasons. These problems have been here overcome neglecting the dependence of spectral densities on the azimuthal angle φ, and adopting a global target approach. In this way, the existing diffusional models can be used to determine dynamic parameters in chiral smectic C phases. An application to the ferroelectric mesogen 8BEF5 is reported. [Copyright &y& Elsevier]

The dynamics of a chiral polymorphic liquid crystal smectogen (8BEF5), partially deuterated on the aromatic core and on the chiral chain, has been investigated in its smectic A and C* phases. The 2H T1Q and T1Z spin–lattice relaxation times, and, consequently, the spectral densities J1(ω0) and J2(2ω0) have been determined for the aromatic as well as methylene deuterons of the chiral chain closer to the aromatic core. The interpretation of the relaxation behaviour has been carried out by means of the available motional models in the SmA phase. Contrary to what is usually observed for other mesogens, in the case of 8BEF5 the internal rotations are much better described by the strong collision model rather than by the small step rotational diffusion one. [Copyright &y& Elsevier]

The article presents a case study on the role of chemistry museums in Chemical Education for students and its impact on the general public in Italy. It analyzes the Italian museums and the scientific collections of chemistry. It presents programs, activities and new perspectives for the future in the integration of the relationship between schools and museums. It discusses the improvement of the role of chemistry museums and considers several practical limitations concerning funds and space.

Olive drupe traits (i.e., ripening index and pericarp water content) and minor components (i.e., phenols and pigments in both fruit and oil) are important for human health and are affected by agronomic background. The aim of this study was to investigate the relationship between fruit traits, phenols, and pigments in samples derived from different soil and water management practices. Chromatographic (UHPLC-MS/MS) and spectroscopic (1HNMR and near UV-Vis spectroscopy) techniques were employed for the characterization of olive fruits and oils. The use of various techniques allowed the identification of interesting trace compounds. We observed that most of the fruit phenols (a total of 29 compounds) were correlated with the degree of ripening: most of the phenolic acids (and their derivatives), phenolic alcohols, and secoiridoids were negatively correlated, whereas the majority of the studied flavonoids were positively correlated. The relationship between the ripening index and fruit phenolic compounds appears to be dependent on the metabolic pathway that controls the synthesis of each individual compound. Conversely, the secoiridoids and pigments in olive oil showed a negative correlation with pulp moisture, probably because of the influence of the water content on the extractability and transfer in the oil phase of these minor components. [ABSTRACT FROM AUTHOR]

Abstract Bimesogenic liquid crystal elastomers, composed with controlled concentrations of two mesogenic constituents, specifically a nematogen and a smectogen, exhibit either enhanced nematic or smectic structure. Here we present a thorough examination of thermomechanical and elastic properties of such a system at high crosslinking density, with ensuing disordered smectic structure which prevents the observation of smectic-nematic phase transition by means of thermomechanical response measurements. Yet, the onset of local smectic order is clearly observable in stress-strain measurements via an anomaly in the elastic modulus. Breakdown of the local smectic structure is detected at higher mechanical loads. Bimesogen composition – temperature phase diagram is as well constructed, consistent with the one obtained by complementary experimental techniques. Stress-strain temperature dependence measurements can thus serve as efficient and simple phase diagram characterization method that is able to detect formation of smectic clusters in strongly crosslinked and thus highly disordered smecto-nematic liquid crystal elastomers. Graphical abstract Image 1 Highlights • Strongly crosslinked bimesogenic liquid crystal elastomers with enhanced nematic (N) or smectic A (SmA) structure. • Investigation of thermomechanical and elastic properties. • No SmA-N phase transition seen by thermomechanical measurements due to high crosslinking density. • All phase transitions can be identified with stress-strain studies, as well as the stress-induced SmA-N phase transition. • Simple approach for determination of bimesogen concentration – temperature – external mechanical stress phase diagram. [ABSTRACT FROM AUTHOR]

Carotenoids and chlorophyll derivatives play a key role in Extra Virgin Olive Oils (EVOOs). Many factors, such as cultivar, geographic origin, maturity of olives, climate and storage conditions, influence the pigments’ content. The quantification of pigments is usually done by chromatographic techniques. However, recent works evidenced the potentialities of UV-visible-related methodologies. In this research, a selection of EVOO samples produced from olives harvested at the beginning of November 2014 in Greece, Tunisia, Italy and Spain, was investigated in terms of pigments by means of two methods. The first one is a recent approach based on the mathematical treatment of near UV-vis absorption spectra of olive oils to quantify in a fast, cheap and non-destructive way four main pigments, namely β-carotene, lutein, pheophytin A and pheophytin B. The second one is a more standard HPLC-DAD method. From the comparison between the two methods, we can conclude that the new near UV-vis approach gives reliable results, with good precision and high reproducibility. Pigments quantified by these two methods in EVOOs produced in four countries from different cultivars are analyzed by principal component analysis (PCA). Results indicate that pigments can be correlated to several factors such as ripeness stage, geographic origin and cultivars. [ABSTRACT FROM AUTHOR]

Microplastics and nanoplastics represent one of the major environmental issues nowadays due to their ubiquitous presence on Earth, and their high potential danger for living systems, ecosystems, and human life. The formation of both microplastics and nanoplastics strongly depends on both the type of pristine materials and the degradation processes related to biological and/or abiotic conditions. The aim of this study is to investigate the effect of two of the most relevant abiotic parameters, namely temperature and light, taken under direct control by using a Solar box, on five types of reference polymers: high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET). A multi-analytical approach was adopted to investigate in detail the first steps of plastics degradation. Samples of plastic materials at different degradation times were analyzed by means of 1H NMR spectroscopy and thermal desorption gas chromatography mass spectrometry (TD-GC-MS) technique. Several minor molecular species released during degradation were consistently identified by both techniques thus providing a comprehensive view of the various degradation products of these five types of microplastics. [ABSTRACT FROM AUTHOR]

ABSTRACT The synthesis of new bitropone derivatives, namely, 3,3'-biphenyl-2,2'-bitropone and 7,7'-biphenyl-2,2'-bitropone, are reported. Isolation of enantiomers arising from restricted rotation around the C-C bond connecting the tropone moieties was attempted by means of chiral (HPLC). No separation was obtained for 7,7'-biphenyl-2,2'-bitropone. For 3,3'-biphenyl-2,2'-bitropone, difficulties were encountered because of the low separation factor of the peaks and the presence of a rapid process. However, quantitative chiroptical data on the antipodes were obtained by linking a circular dichroism (CD) spectrometer and a UV-vis spectrophotometric detector in series to the HPLC instrument. The analysis of the CD and UV-vis spectra in terms of absolute conformations was done with the help of theoretical calculations performed at the Density Functional Theory (DFT) level. The most stable conformations of the 3,3'-biphenyl-2,2'-bitropone in its ground state were obtained. Starting from these minimum energy conformations, it was possible to compute theoretical CD and UV absorption spectra that fit well with the experimental ones. From this comparison the absolute configuration to the antipodes was assigned. Finally, the effect of the presence of the two lateral phenyl substituents on the structure of the bitropone and hence on the CD spectrum is discussed. Chirality 25:648-655, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We investigate light-induced patterning of a monodomain side-chain liquid crystal elastomer (SC-LCE) doped with light-sensitive azobenzene moiety in the temperature region close to the nematic-paranematic phase transition. We show that a strongly nonlinear relationship between the concentration of the cis isomers of the azomesogens and the refractive index modification of the material, which is characteristic for the phase transition region, results in nonmonotonous time dependence of the diffraction efficiency of a probe beam. From this effect we determine the sensitivity of the nematic transition temperature on the molar fraction of the cis isomers. The relation between the cis isomer molar fraction and nematic order also provides a possibility for recording hidden holograms, which can be made visible by cooling the sample from the paranematic to the nematic phase. [ABSTRACT FROM AUTHOR]

The optical mechanism for imprinting one-dimensional grating structures into thin films of a light-sensitive monodomain liquid crystal elastomer is investigated by analyzing the time dependence of optical diffraction properties. The recording kinetics shows an irregular oscillatory behavior, which is most expressed at small grating spacings and at temperatures close to the nematic-isotropic phase transition. The oscillations are attributed to the opto-mechanical response of the film, i.e., to contraction of the film during the recording process. At temperatures far below the nematic-isotropic phase transition, the spontaneous erasure kinetics exhibits exponential relaxation with relaxation time following the Arrhenius activation law. However, at temperatures close to the nematic-isotropic phase transition, the erasure process shows an interesting nonmonotonic behavior that we attribute to the non-linear relation between the concentration of the photo-transformed chemical groups and the nematic order parameter. [ABSTRACT FROM AUTHOR]

The orientational order parameters, Szz and Biax, of UB-d4 [1,4-bis(undec-10-en-1-yloxy)benzene-d4 ] in the ZLI1167 nematic mixture are studied by means of 2H NMR at variable temperature. The Szz(T) trend fairly follows the Maier–Saupe theoretical curve; therefore, UB-d4 can be considered an excellent probe to monitor the ordering of the nematic phase itself, provided that Biax is not neglected and the complete analysis of quadrupolar and dipolar splittings is performed. UB-d4 is a typical crosslinker in liquid crystal elastomers (LCEs): the order parameters here collected help us to discuss the peculiarities of the crosslinker as a probe for the study of internal order in LCEs. From the analysis of our data and of data in the literature, we infer that the order parameter Biax of the crosslinker in the LCE matrix is low enough to be neglected without severely perturbing the determination of . The crosslinker UB-d4 is a reliable probe to monitor the nematic order degree inside the LSCE-UB-d4 sample. [ABSTRACT FROM AUTHOR]

We investigated nonlinear absorption and photobleaching processes in a liquid-crystal elastomer doped with light-sensitive azobenzene moiety. A conventional one-dimensional holographic grating was recorded in the material with the use of two crossed UV laser beams and the angular dependence of the diffraction efficiency in the vicinity of the Bragg peak was analyzed. These measurements gave information on the depth to which trans to cis isomerization had progressed into the sample as a function of the UV irradiation time. Using a numerical model that takes into account the propagation of writing beams and rate equations for the local concentration of the absorbing trans conformer, we computed the expected spatial distribution of the trans and cis conformers and the shape of the corresponding Bragg diffraction peak for different irradiation doses. Due to residual absorption of the cis conformers the depth of the recording progresses logarithmically with time and is limited by the thermal relaxation from the cis to trans conformation. [ABSTRACT FROM AUTHOR]

We investigated by 2 H NMR spectroscopy a ferroelectric liquid crystalline polysiloxane (poly11EB1M7- d 2 ) derived from the mesogen (+)( S ) 4-[4′-(1-methylheptyloxy)]biphenyl 4-(10-undecenyloxy)benzoate- d 2 (11EB1M7- d 2 ). The labelling on the phenyl fragment allowed us to study the orientational order of such unit. From the analysis of the deuterium lineshapes we could also determine the effect of the magnetic field on the mesogen alignment and the ferroelectric helix distortion. In particular, deuterium spectra showed a contribution due to aligned mesogens in addition to a "Pake-like" one. This was accounted for by considering isotropic distribution of helices, with possible helix distorsion. [ABSTRACT FROM AUTHOR]

In this work, we present the synthesis of two analogues of a lactic acid derivative selectively deuterated on phenyl and biphenyl moieties together with a detailed investigation of their properties within the Twist Grain Boundary smectic A* (TGBA*), the ferroelectric Smectic C* (SmC*) and the crystal E phases. The main structural features of the two liquid crystalline phases, namely TGBA* and SmC* phases, were determined by polarising optical microscopy, differential scanning calorimetry, electro-optical techniques, Small Angle X-ray Scattering (SAXS) and 2H Nuclear Magnetic Resonance (2H NMR) measurements. Preliminary results from Neutron Spin-Echo (NSE) spectroscopy, a technique rarely applied to study chiral liquid crystalline materials, are reported. The effect of the external magnetic field on the supramolecular structure of the ferroelectric phase was studied by means of 2H-NMR experiments under different external magnetic fields. The supramolecular and orientational ordering properties of this ferroelectric lactic acid derivative and its deuterated homologues are discussed in the frame of actual knowledge in the field of ferroelectric liquid crystal materials. [ABSTRACT FROM AUTHOR]

Several side-chain liquid single crystalline elastomers (LSCEs) were investigated by means of ²H NMR spectroscopy focusing on the temperature dependence of the spectral line width and spectral shape, as well as the T-dependence of spin-lattice and spin-spin relaxation times (T1 and T2). All measurements were performed at the Larmor frequency of 76.753 MHz for ²H. The LSCEs were prepared in the form of monodomain films by using either ²H-labelled monomers (or co-monomers), ²H-labelled cross-linkers or ²H-labelled molecular probes free to diffuse in the LSCE matrix. In all cases, deuterons are on the phenyl moiety. The main features of the measured ²H NMR properties (static and dynamic ones) in these different cases were discussed and comparedwith those of low-molecular-weightmesogens (i.e. the same molecules used as monomers or co-monomers in the side-chain LSCEs) in the nematic and smectic A phases. Among all investigated LSCE samples, those ²H-labelled on the cross-linker sites present distinct properties either on the ²H NMR spectral line width and spectral shape in the paranematic and in the nematic phases, which can be interpreted in terms of director reorientational dynamics in the intermediate-slow motional regime, taking into account the inherent local director misalignment of LSCEs. [ABSTRACT FROM AUTHOR]

This study analyzed the effect of low sulfur dioxide concentrations on the chromatic properties, phytochemical composition and antioxidant activity of Aglianico red wines with respect to wines produced from conventional winemaking. We determined the phytochemical composition by spectrophotometric methods and HPLC-DAD analysis and the in vitro antioxidant activity of different wine samples by the ORAC assay. The main important classes of fluorophore molecules in red wine were identified by Front-Face fluorescence spectroscopy, and the emission intensity trend was investigated at various sulfur dioxide concentrations. Lastly, we tested the effects of both conventional and low sulfite wines on ex vivo human erythrocytes under oxidative stimulus by the cellular antioxidant activity (CAA) assay and the hemolysis test. The addition of sulfur dioxide, which has well-known side effects, increased the content of certain bioactive components but did not raise the erythrocyte antioxidant capacity. [ABSTRACT FROM AUTHOR]

Dry and fresh apples have been studied monitoring their polyphenolic profiles through 1 H NMR, antioxidant capacity and total polyphenol content. Six ancient and underutilized apple varieties (Mantovana, Mora, Nesta, Cipolla, Ruggina, Sassola) and a commercial one (Golden Delicious) were dried with an air-drying system at 45 °C for 19 h. Although some of their polyphenol constituents were lost during drying, the antioxidant capacity of some apple varieties remained higher compared to Golden Delicious. This result is very important for ancient and underutilized varieties that are not consumed on large scale as fresh product since they have low attractiveness, due to their ugly appearance. Combining quantitative NMR spectroscopy with principal component analysis we have identified and quantified several polyphenols (such as catechin, epicathechin, and chlorogenic acid) that are important to establish the nutraceutical value of the different investigated apple varieties. [ABSTRACT FROM AUTHOR]

The aim of this work was to analyze the effect of a microbiological consortium, in particular mycorrhizal fungi, on the phytochemical composition and on the antioxidant properties of Sangiovese wines with respect to wines from conventional agriculture, paying particular attention to their oxidative stability following oxygen exposure. We determined by spectrophotometric methods and HPLC-DAD the phytochemical composition and by ORAC assay the antioxidant activity of wines. Besides, in order to evaluate the beneficial effects of both symbiotic and conventional wines, we investigated on human erythrocytes the cellular antioxidant activity (CAA) and the hemolysis inhibition. Our results showed that symbiotic wines had both a better oxidative stability and a significantly higher level of bioactive compounds compared to the conventional ones. Despite the bioactive compounds variation, no difference in antioxidant capacity was found. However, erythrocytes pre-treated with symbiotic wines exhibited higher biological activities than the equivalent conventional one. In conclusion, the use of a microbiological consortium represents an ecologically and economically relevant solution in vineyard cultivation to get high-quality wines, with improved nutritional and nutraceutical value. [ABSTRACT FROM AUTHOR]

We present the characterization of new binary mixtures made of two rod-like molecules: a photosensitive azobenzene derivative (calledJ7) and a smectogen (calledM11). The interest in these two specific compounds is related to their use as basic constituents of photo-active liquid crystalline elastomers and their opto-mechanic applications. Differential scanning calorimetry and polarized optical microscopy were used to characterize the phase diagram of the binary systemJ7-M11.2H NMR spectroscopy of the2H-selectively labelledM11, either alone or as a probe in binary mixtures containing different ratiosJ7/M11, was applied to study the orientational ordering properties. [ABSTRACT FROM PUBLISHER]

Several experimental techniques have been used to investigate the chemical-physical properties of new functionalized ultra-small iron-oxide nanoparticles (USPION), which are of interest for biomedical applications. The chemical composition of oleate-coated iron-oxide (OA-NPs) and cystine-coated iron-oxide (Cy-NPs) nanoparticles was investigated by means of analytical methods and Fourier transform infrared (FT-IR) spectroscopy. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) investigations, at high and low resolutions, on both OA-NPs and Cy-NPs, were performed to investigate their morphology. The magnetization and susceptibility behavior of OA- and Cy-NPs were studied by SQUID magnetometry. The combination of different experimental techniques was of help in characterizing the chemical structure of both magnetic core and surface-coating of OA- and Cy-NPs. AFM/TEM images and magnetic measurements were analyzed in terms of crystallinity, polydispersity, average magnetic core size, and coating effects of these nanoparticles. These results show that the preparations reported in the present paper are effective in obtaining nanoparticles of 4 nm magnetic core size and the procedure is highly reproducible. The presence of the external cystine shell, fundamental for biomedical applications, does not affect the polidispersity, the crystallinity or the average core size. Moreover, similar values of the average core dimensions have been obtained by three different techniques (AFM and TEM images, magnetic measurements). Graphical Abstract: New cystine-functionalized magnetite nanoparticles have been synthesized. Physical chemical investigations show an average core size of about 4 nm and super-paramagnetic properties.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We synthesised a series of rod-like mesogens with a (S)-2-methylbutyl-(S)-lactate unit in the chiral chain that exhibited extremely wide temperature ranges in the TGBA and TGBC* phases. TGB phases were identified, based on typical textures in confined samples and in free-standing films, by Grandjean-Cano texture and by NMR studies on a deuterium-labelled isotopomer. A sufficiently high electric or magnetic field transformed the TGBA and TGBC* phases into their respective SmA and SmC* phases, the TGB structures being restored within some 20-30 minutes. Therefore values of the spontaneous polarisation and spontaneous tilt angle, when measured under a sufficiently high field, gave evidence of the properties of the SmC* phase. Temperature dependencies of relaxation frequency, dielectric strength, selective reflection and layer spacing showed anomalies at a certain temperature within the TGBC* phase range. Also, changes in textures, as well as in 2H-NMR spectra, occurred at this same temperature. These results suggest the existence of two TGBC* phases. [ABSTRACT FROM AUTHOR]