Photoelectron Circular Dichroism as a Probe of Chiral Hydrocarbons

The sensitivity of Photoelectron Circular Dichroism (PECD) in the angular distribution of photoelectrons, a recent chiral technique, to detect chirality in pure hydrocarbons is investigated in a number of benchmark molecules. It is found that a very large chiral signal is expected, surpassing most current examples, giving a sure fingerprint of absolute configuration. On the other hand, the sensitivity to specific isomers or closely related molecules is relatively modest.

Nanoencapsulated Myricetin to Improve Antioxidant Activity and Bioavailability: A Study on Zebrafish Embryos

Flavonoids are natural polyphenolic compounds that mainly possess antioxidant properties due to more hydroxyl groups in their structure and play an important role in combatting many diseases. Myricetin is a flavonoid found in grapes, green tea, fruits, and vegetables and is not only an antioxidant but also is a pro-oxidant. Myricetin is sparingly soluble in water and restricts its properties due to low bioavailability. The present study reports the liposomal nanoformulations of myricetin to improve its bioavailability with reduced pro-oxidant activity. The nanoformulated myricetin was characterized using different photophysical tools, such as dynamic light scattering (DLS), zeta potential, and scanning electron microscopy (SEM). The effect of nanoencapsulated myricetin on the developing zebrafish embryo was studied in terms of microscopic observations, cumulative hatchability, and antioxidant activities, such as catalase, glutathione peroxidase, and superoxide dismutase, after treating the zebrafish embryo with standard oxidant hydrogen peroxide. The results obtained from the cumulative hatchability, developmental studies, and antioxidant assays indicated that the liposomal nanoformulation of myricetin had enhanced antioxidant activity, leading to defense against oxidative stress. The formulation was highly biocompatible, as evidenced by the cumulative hatching studies as well as microscopic observations. The positive effects of liposomal nanoformulation on zebrafish embryos can open an avenue for other researchers to carry out further related research and to check its activities in clinical studies and developmental studies.

Complexation Behavior of Pinene–Bipyridine Ligands towards Lanthanides: The Influence of the Carboxylic Arm

The complexation behavior of two novel, chiral pinene–bipyridine-type ligands ((–)-HL1 and (–)-HL2) containing a carboxylic arm towards lanthanide Ln(III) (Ln = La, Eu, Lu) ions was investigated through spectroscopic methods. The association constants of the mononuclear complexes determined from the UV-Vis titrations indicated that the ligand (–)-HL1 possessing a shorter carboxylic arm formed more stable complexes compared with (–)-HL2, whose carboxylic arm had one more methylene unit. This is due to the formation of more stable seven-member metal chelate rings in the first case as compared with the eight-member metal chelate rings in the second. IR and fluorescence spectroscopy provided additional information about the structure of these complexes.

Fully Biobased Reactive Extrusion of Biocomposites Based on PLA Blends and Hazelnut Shell Powders (HSP)

The production of biocomposites based on natural fiber waste and biopolymers is constantly increasing because of their renewability, biodegradability, and the accordance with the circular economy principles. The aim of this work is to contrast the disadvantages in the production of biocomposites, such as reduction of molecular weight through the use of biobased chain extenders. For this purpose, epoxidized soybean oil (ESO) and dicarboxylic acids (DCAs) were used to contrast the slight chain scission observed in a poly(lactic acid) (PLA)/poly(butylene succinate-co-adipate) (PBSA) binary blend caused by the melt mixing with hazelnut shell powder (HSP). Two different dimensions of HSPs were considered in this study as well as different concentrations of the ESO/DCA system, comparing succinic acid and malic acid as dicarboxylic acids. Melt viscosity parameters, such as torque and melt volume rate (MVR), were measured to investigate the chain extender effect during the extrusion. In addition, the reactivity of the ESO/DCA system was investigated through infrared spectroscopy. The effect of chain extenders on thermal properties, in particular on the crystallinity of PLA, and on mechanical properties of final biocomposites was investigated to understand their potentialities in industrial application. Results of this study evidenced a modest increase in melt viscosity due to ESO/malic acid chain extension system, but only for the HSP with the lower dimension (so the higher surface area) and adding 0.5 wt.% of ESO/malic acid. Thus, the slight chain scission of polyesters, not significantly affecting the final properties of these biocomposites, is the most relevant effect that was revealed in this complex reactive system.

Occurrence of Marine Ingredients in Fragrance: Update on the State of Knowledge

The fragrance field of perfumes has attracted considerable scientific, industrial, cultural, and civilizational interest. The marine odor is characterized by the specific smell of sea breeze, seashore, algae, and oyster, among others. Marine odor is a more recent fragrance and is considered as one of the green and modern fragrances. The smells reproducing the marine environment are described due to their content of Calone 1951 (7-methyl-2H-1,5-benzodioxepin-3(4H)-one), which is a synthetic compound. In addition to the synthetic group of benzodioxepanes, such as Calone 51 and its derivatives, three other groups of chemical compounds seem to represent the marine smell. The first group includes the polyunsaturated cyclic ((+)-Dictyopterene A) and acyclic (giffordene) hydrocarbons, acting as pheromones. The second group corresponds to polyunsaturated aldehydes, such as the (Z,Z)-3,6-nonadienal, (E,Z)-2,6-nonadienal, which are most likely derived from the degradation of polyunsaturated fatty acids. The third group is represented by small molecules such as sulfur compounds and halogenated phenols which are regarded as the main flavor compounds of many types of seafood. This review exposes, most notably, the knowledge state on the occurrence of marine ingredients in fragrance. We also provide a detailed discussion on several aspects of essential oils, which are the most natural ingredients from various marine sources used in fragrance and cosmetics, including synthetic and natural marine ingredients.

Aromaticity of Heterocirculenes

This review summarizes the results on the aromaticity of a series of synthesized and hypothetical neutral heterocirculene molecules and their double charged ions. The aromaticity of heterocirculenes is a direct reflection of their electronic structure responsible for the specific optoelectronic and photophysical properties. We show how the presence of a heteroatom in the outer macrocycle affects the aromaticity of hetero[8]circulenes. In addition, we also describe the change in aromaticity and strain energy for a series of the “lower” (n < 8) and “higher” (n > 8) hetero[n]circulenes. It was demonstrated that the loss of planarity with increased strain leads to an increased antiaromaticity of the lower hetero[n]circulenes, whereas higher hetero[n]circulenes demonstrate a more pronounced aromatic nature because of the small departure from planarity of each heteroarene ring in hetero[n]circulene molecule. Finally, we discuss the aromatic nature of the first examples of π-extended hetero[8]circulenes.

On-Surface Synthesis of Boroxine-Based Molecules

The on-surface synthesis of boroxine-containing molecules can be a convenient method of introducing specific functionalities. Here, we show the validity of a previously described synthesis protocol on the Au (111) surface by applying it to a different molecular precursor. We study in detail the assembly of the precursor, highlighting possible intermediate stages of the condensation process. We combine scanning tunneling microscopy and X-ray spectroscopies to fully characterize both the morphology and the electronic properties of the system. DFT calculations are presented to assign the main electronic transitions originating the B K-edge absorption spectrum. The study paves the way to a facile strategy for functionalizing a surface with molecules of tailored sizes and compositions.

Degradation of Polypropylene and Jute Fiber-Reinforced Composites Exposed to Natural and Accelerated Aging: Mechanical Properties and Wettability

Population growth and the way resources are being exploited are directly affecting the environment. The natural fiber market, for example, is worth billions of dollars and a huge amount of the fibers becomes waste. This considerable amount of waste motivates the study of the fibers as a reinforcement in polymeric matrix, which benefits both the environmental sustainability and technical-commercial development of new materials with good properties and reduced cost. In this study, jute fiber-reinforced composites previously manufactured from an industrial waste (W), polypropylene, compatibilizer, and nano-calcium carbonate (N), were exposed to natural and accelerated aging. The composites were tested by infrared spectroscopy, contact angle (CA) measurement, and tensile test. Infrared analysis showed greater oxidative degradation after accelerated aging. All CA values continued above 90° after natural aging. Among all compositions, the ones with the presence of N had the highest CA values, showing that N acted as a waterproofing agent. After accelerated aging, a significant decrease in all CA values was observed. The composites did not show significant variation in the elastic modulus after either aging. Deformation at break decreased significantly for compositions with no jute fiber in both aging programs. No remarkable reduction was observed in the compositions with jute fibers.

The Magnetic Response of Starphenes

The aromaticity of [n]starphenes (n = 1, 4, 7, 10, 13, 16), as well as starphene-based [19]dendriphene, is addressed by calculating the magnetically induced current density and the induced magnetic field, using the pseudo-π model. When an external magnetic field is applied, these systems create diatropic currents that split into a global peripheral current surrounding the starphene skeleton and several local currents in the acene-based arms, resulting in large shielding cones above the arms. In particular, the arm currents are smaller than their linear analogs, and in general, the strengths of the ring currents tend to weaken as the starphene get larger.

Investigation of SiO2 Nanoparticle Retention in Flow Channels, Its Remediation Using Surfactants and Relevance of Artificial Intelligence in the Future

In this study, the effect of these variables on commercial silica NP retention was presented in a fabricated flow model considering only the physical adsorption aspects of silica NP retention. From our observations, it was established that while silica NP concentration, flow rate and salt are key variables in influencing silica NP agglomeration and retention, the effect of temperature was highly subdued. The effect of salt-induced agglomeration was particularly severe at moderate salinity (≈4 wt% NaCl). To mitigate the effect of salt-induced agglomeration, a commonly used anionic surfactant, sodium dodecyl sulfate (SDS) was added to the solution and the silica NP retention was tabulated. An amount of 0.3 wt% SDS was found to negate salt-induced agglomeration significantly, paving the way for use of silica NP solutions, even in the presence of saline conditions. A section on the prospective use of artificial intelligence for this purpose has been included. This study is useful for understanding NP retention behaviour, especially in the presence of salinity and its mitigation using surfactants, in flow applications.