Effect of Pyridine on the Mesophase of Teraryl Liquid Crystals: A New Series of Nematic Liquid Crystals Named 2-(4-Alkoxybiphen-4′-yl)-5-methylpyridines

Abstract

A new series of teraryl 2-(4-alkoxybiphen-4′-yl)-5-methylpyridines (nO-PPPyMe, n = 3–8) nematic liquid crystal compounds, bearing a biphenylene core and a picoline terminus, were synthesized using a short two-step reaction, and overall yields between 34% and 38% were obtained. Spectral analysis results were in accordance with the expected structures. The thermotropic behavior of the teraryl liquid crystal compounds was investigated through polarized optical microscopy and differential scanning calorimetry. All compounds exhibited a solely enantiotropic nematic phase at the medium–high temperature range of 162.4–234.2 °C. Furthermore, the results for the nO-PPPyMe series were analyzed relative to three other compound series, mO-PPPyCN (m = 2–8), iO-PPQMe (i = 3–8) and xO-PPyPMe (x = 1–10). Consequently, the effect of pyridine on the mesophase of teraryl liquid crystals was demonstrated.

Entropy Density Acceleration and Minimum Dissipation Principle: Correlation with Heat and Matter Transfer in Glucose Catabolism

“…Basing on the analogy between the behavior of mechanical systems and thermodynamic systems, we redefine this concept in out-of-equilibrium thermodynamics. We remind that this concept derived from mechanics and applied to thermodynamics is not an end in itself and the model developed does not represent a mere theorization but tries to describe reality, as it is consistent with the experimental data of several works [ 11 , 12 , 13 , 14 , 15 ].…”

“…Since the observation of a prevalent lactic acid fermentation in cancer cells, the so-called Warburg effect or aerobic glycolysis, many efforts were done to understand the origin of this behavior in cancer cells and cancer stem cells [ 9 , 10 , 11 ]. On the other hand, in the last years also the study of the metabolic network and of the mitochondria network have received a special attention [ 12 ].…”

“…In recent years, the strict connection between thermodynamic irreversibility and information resulting from the strong influence of metabolic patterns on genetic and epigenetic patterns in biological systems, the study of the generation of entropy in normal, cancer and stem cells has also been highlighted and demonstrated [ 11 , 12 , 13 , 14 , 15 ]. Attention should focus not only on cell biology, but also on the thermodynamic description of cells and of the living systems because this different perspective could offer a unitary view of metabolomics, genomics and epigenomics.…”

Synthesis and characterization of new pyridine-based chiral calamitic liquid crystals

“…Recently, a variety of pyridine containing liquid crystalline compounds were synthesized, 7,15,16,17 most of them were rod-like calamitic liquid crystals, but only few examples presenting nicotinate and picolinate as building blocks were reported, in order to determine the effect of 2-, 3-, and 4-pyridyl rings relative to phenyl in promoting mesophase thermal stability. 10,18 However, several Japanese patents were published concerning optically active liquid crystal based on pyridine carboxylate, demonstrating the importance of this type of patterns for technological applications.…”