Ligand synthesis catalyst and complex metal ion: multicomponent synthesis of 1,3-bis(4-phenyl-[1,2,3]triazol-1-yl)-propan-2-ol copper(i) complex and application in copper-catalyzed alkyne-azide cycloaddition

A new bistriazole copper complex was synthesized by direct treatment of an alkyne, an azide, and CuI as copper salt through in situ ligand formation under a multicomponent reaction process. This complex was analyzed by XPS, TGA, DSC, and SEM techniques and revealed a triangular-shapedmorphology, high thermal stability, and catalytic power in CuAAC reactions, requiring only 2.5% mol catalyst to afford 1,2,3-triazoles in good yields which can be reused at least for 4 cyclesCONACYT, proyecto 13505

Deliciosos polimorfos

El polimorfismo, tan habitual y conocido por geólogos en minerales como la calcita-aragonito, el diamante-grafito y el grupo de la sílice, se extiende a muchos otros campos. Desde la cristalografía y la mineralogía, dando un gran salto en los materiales pero no en los fenómenos, el polimorfismo también tiene lugar en productos alimentarios. En particular, los triacilgliceroles, los cuales constituyen los componentes mayoritarios de grasas y aceites, tales como el chocolate, el aceite de oliva o el jamón ibérico, muestran un complejo comportamiento polimórfico (Larsson et al., 2006). La caracterización de sus formas cristalinas resulta crucial en aplicaciones de la industria alimentaria para satisfacer las necesidades del consumidor, optimizar procesos industriales o desarrollar nuevos productos. Sin embargo, el polimorfismo también podría ser utilizado como herramienta discriminatoria entre diferentes categorías de un mismo producto alimentario, así como para la detección de acciones fraudulentas (Bayés-García et al., 2016)

Chocolate: a useful model for teaching basic terms on Crystallography and Thermodynamics

By using a simple, attractive and sweet model, as chocolate is, many scientific concepts related to different disciplines, which are often understood as complex and dull by most students, may be introduced. In particular, the student may be able to develop crystallographic concepts and methodologies combined with some thermodynamic aspects, which have been historically known as complex and arduous disciplines. Hence, the student may enjoyably assimilate complicated concepts such as polymorphism, mixing behavior, crystal morphology, crystal size or thermodynamic stability, and may also be capable of understanding their application to daily life. These concepts may be applicable to any kind of material and can be more deeply developed depending on the level required

Polymorphism, crystal growth, crystal morphology and solid-state miscibility of alkali nitrates

In this review, we recollect and discuss the most relevant advancement in crystallographic aspects of alkali nitrates compounds published since 1975, the year of publication of the last review by Rao et al. about some topics discussed here. This review is focused in five nitrate compounds of the first periodic table column: LiNO3, NaNO3, KNO3, RbNO3 and CsNO3. For each one, we have compiled the information about crystal structure, polymorphism and phase transition, crystal growth and crystal morphology, and the phase diagram and solid-state miscibility results. Considerable numbers of papers have been published in the last 40 years, in particular in relation to binary phase diagrams and solid-state miscibility of alkali nitrates. A variety of phase diagram descriptions appears in the 10 possible binary combinations for the five compounds. To finish, we discuss and propose a geometric model in order to explain the different binary phase diagrams observed between these compounds

The NaNO3- KNO3 phase diagram

Many papers have been published in relation to the NaNO3-KNO3 phase diagram determination in the last 160 years. These papers fall in two categories: (1) the solid-liquid equilibrium is assumed to be of the eutectic type, and (2) the solid-liquid equilibrium is considered as a loop with a minimum. The discordance between the two views is related to the slow transition kinetics that complicate the assessment of thermal 'fluctuations', and also to the appearance of a metastable form of potassium nitrate. The main result of this paper is the experimental phase diagram constructed with new experimental data so that we can assure that the second option is correct. This phase diagram is defined by a eutectoid invariant, an asymmetric immiscibility gap and a continuous solid solution with a minimum of melting point. Additionally, the ABu model simulates correctly the experimental piece of evidence

In situ crystallization and transformation kinetics of polymorphic forms of saturated-unsaturated-unsaturated triacylglycerols: 1-palmitoyl-2,3-dioleoyl glycerol, 1-stearoyl-2,3-dioleoyl glycerol, and 1-palmitoyl-2-oleoyl-3-linoleoyl glycerol

We examined the influence of dynamic thermal treatment (variation of cooling/heating rates) on the polymorphic crystallization and transformation pathways of 1-palmitoyl-2,3-dioleoyl glycerol (POO), 1-stearoyl-2,3-dioleoyl glycerol (SOO), and 1-palmitoyl-2-oleoyl-3-linoleoyl glycerol (POL), which are major saturated-unsaturated-unsaturated (SUU) triacylglycerols (TAGs) of vegetable oils and animal fats (e.g., palm oil, olive oil, and Iberian ham fat). Using mainly a combination of differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffraction (SR-XRD), we analyzed the polymorphic behavior of TAGs when high (15 °C min− 1), intermediate (2 °C min− 1), and low (0.5 °C min− 1) cooling and heating rates were applied. Multiple polymorphic forms were detected in POO, SOO, and POL (sub-α, α, β'2, and β'1). Transient disordered phases, defined as kinetic liquid crystal (KLC) phases, were determined in POO and SOO for the first time. The results demonstrated that more stable forms were directly obtained from the melt by decreasing the cooling rates, whereas less stable forms predominated at high cooling rates, as confirmed in our previous work. Regarding heating rate variation, we confirmed that the nature of the polymorphic transformations observed (solid-state, transformation through KLC phase, or melt-mediation) depended largely on the heating rate. These results were discussed considering the activation energies involved in each process and compared with previous studies on TAGs with different saturated-unsaturated structures (1,3-dioleoyl-2-palmitoylglycerol, 1,3-dipalmitoyl-2-oleoyl-glycerol, trioleoyl glycerol, and 1,2-dioleoyl-3-linoleoyl glycerol)

From trioleoyl glycerol to extra virgin olive oil through multicomponent triacylglycerol mixtures: crystallization and polymorphic transformation examined with differential scanning calorimetry and X-ray diffraction techniques

The polymorphic crystallization and transformation behavior of extra virgin olive oil (EVOO) was examined by using differential scanning calorimetry (DSC) and X-ray diffraction with both laboratory-scale (XRD) and synchrotron radiation source (SR-XRD). The complex behavior observed was studied by previously analyzing mixtures composed by its main 2 to 6 triacylglycerol (TAG) components. Thus, component TAGs were successively added to simulate EVOO composition, until reaching a 6 TAGs mixture, composed by trioleoyl glycerol (OOO), 1-palmitoyl-2,3-dioleoyl glycerol (POO), 1,2-dioleoyl-3-linoleoyl glycerol (OOL), 1-palmitoyl-2-oleoyl-3-linoleoyl glycerol (POL), 1,2-dipalmitoyl-3-oleoyl glycerol (PPO) and 1-stearoyl-2,3-dioleoyl glycerol (SOO). Molten samples were cooled from 25 °C to − 80 °C at a controlled rate of 2 °C/min and subsequently heated at the same rate. The polymorphic behavior observed in multicomponent TAG mixtures was interpreted by considering three main groups of TAGs with different molecular structures: triunsaturated OOO and OOL, saturated-unsaturated-unsaturated POO, POL and SOO, and saturated-saturated-unsaturated PPO. As confirmed by our previous work, TAGs belonging to the same structural group displayed a highly similar polymorphic behavior. EVOO exhibited two different β'-2 L polymorphic forms (β'2-2 L and β'1-2 L), which transformed into β'-3 L when heated. Equivalent polymorphic pathways were detected when the same experimental conditions were applied to the 6 TAG components mixture. Hence, minor components may not exert a strong influence in this case

External factors affecting polymorphic crystallization of lipids

Many physical properties (e.g., hardness, texture, rheology, and spreadability) of lipid‐based products largely depend on the extent of crystallization and transformation of lipids, and their network formation. Therefore, many studies have focused on controlling the crystallization of lipids in order to determine the functionality of lipid crystals. Both internal and external factors greatly affect the processes of lipid crystallization. The most important internal factors are polymorphism, which depends on variation in fatty acid moieties, and the composition or blending of different lipid materials. Important external factors are thermal treatment, additives, application of shear, sonication, and pressure. This paper briefly reviews recent advances in research on these external factors. We discuss the results by considering the relationships between external factors and thermodynamics, as well as kinetic properties of the crystallization and transformation of polymorphic forms of lipid crystals

Polymorphic crystallization and kinetic pathways of triacylglycerols

The kinetic properties of crystallization and structural transformation are important, particularly for the application of polymorphic crystal systems in pharmaceutical, biomedical, food technology, and other applications. Triacylglycerols (TAGs) are the main components of alimentary fats and oils. Fat structures and compositions determine their physical properties (e.g., rheology, morphology, and texture), where polymorphism exerts a strong influence. There are different polymorphic forms of TAGs: the most general ones (in increasing stability) are: α form, which crystallizes in the hexagonal system, β' form (orthorhombic system) and β form (triclinic system). In this study, several techniques, like Synchrotron Radiation X-Ray Diffraction, Thermal Analysis and Thermo-optical Microscopy, were used in order to characterize the polymorphism under the kinetic point of view of some TAGs present in edible oils and fats. Therefore, the role of some kinetic parameters (e.g. cooling and heating rates) is highlighted

Phase behavior of binary mixture systems of saturated-unsaturated mixed-acid triacylglycerols: effects of glycerol structures and chain−chain interactions

We systematically examined the phase behavior of binary mixtures of mixed-acid triacylglycerols (TAGs) containing palmitic and oleic acid moieties 1,3-dioleoyl-2-palmitoyl-glycerol (OPO), 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO), and 1,2-dioleoyl-3-palmitoyl-rac-glycerol (OOP), which are widely present in natural fats and are employed in the food, pharmaceutical, and cosmetic industries. Differential scanning calorimetry and X-ray diffraction methods were applied to observe the mixing behavior of PPO/OPO, OOP/OPO, and PPO/OOP under metastable and stable conditions. The results led to three conclusions: (1) Eutectic behavior was observed in PPO/OPO. (2) Molecular compound (MC) crystals were formed in the mixtures of OOP/OPO and PPO/OOP. (3) However, the MC crystals occurred only under metastable conditions and tended to separate into component TAGs to form eutectic mixture systems after 17 months of incubation. These results were contrary to those of previous studies on 1,3-dipalmitoyl-2-oleoyl glycerol (POP)/OPO and POP/PPO in which the MC crystals were thermodynamically stable. We determined that specific molecular interactions may cause this different phase behavior (stability of POP/OPO and POP/PPO MC crystals and metastability of OOP/OPO and PPO/OOP MC crystals). All results confirm the significant effects of molecular structures of glycerol groups, interactions of fatty acid chains, and polymorphism of the component TAGs on the mixing behavior of mixed-acid TAGs