Recent Advances in Metal Catalyst Design for CO2 Hydroboration to C1 Derivatives

The use of CO2 as a C1 building block for chemical synthesis is receiving growing attention, due to the potential of this simple molecule as an abundant and cheap renewable feedstock. Among the possible reductants used in the literature to bring about CO2 reduction to C1 derivatives, hydroboranes have found various applications, in the presence of suitable homogenous catalysts. The current minireview article summarizes the main results obtained since 2016 in the synthetic design of main group, first and second row transition metals for use as catalysts for CO2 hydroboration.

Methane and Mars

This chapter talks about the astronomers who have been searching for evidence of methane in the atmosphere of Mars for half a century and trying to address the question of why it is there. It clarifies that methane is a simple molecule that packs a very powerful astrobiological punch and is impossible to exist in the oxygen-rich, hydrogen-poor Martian environment without it being actively created by living things. It also points out how the discovery of methane in the atmosphere of Mars could be unequivocal proof that life exists or existed on Mars. The chapter explains that methane is a colorless, odorless gas that is the simplest possible molecule composed of both and only hydrogen and carbon atoms. It emphasizes that methane in the Martian atmosphere simply cannot survive for long and it could have been converted to carbon dioxide and water.

Terpenes in Essential Oils: Bioactivity and Applications

Secondary metabolites from plant organisms have always been excellent options for the pharmaceutical, cosmetic, and food industries. Essential oils are a type of metabolites found in vegetables, and their chemical composition is diverse; however, monoterpenes and sesquiterpenes are inside the most abundant molecules. These terpenes have a diverse chemical composition that range from a simple molecule with carbon and hydrogen to more complex molecules with oxygenated organic groups, such as alcohols, aldehydes, ketones, and ethers. Many of these molecules with 10 and 15 carbon atoms have an especially important biological activity, being important the antimicrobial, antifungal, antioxidant, anti-inflammatory, insecticide, analgesic, anticancer, cytotoxic, among others. Some of these substances are potentially toxic, and hence, they should be handled with caution, especially when they are pure. They are easily obtained by different methods, and their industrial value grows every year, with a market of several million dollars. This chapter seeks to provide a better understanding of this type of bioactive molecules, with an emphasis in those whose information is remarkable in the scientific literature and whose value for health and human well-being makes them extremely important.

Isomerization of cyanopropyne in solid argon

Cyanopropyne, CH3–CC–CN, is a simple molecule whose photochemistry we have explored. UV photolysis of this molecule in an Ar matrix was performed and quantum chemical calculations used to better understand photoproduct production.

Synthesis of 5,6-Diaminoacenaphthylene by Reduction of Sterically Crowded Nitro Groups with Sodium Dithionite

5,6-Diaminoacenaphthylene was synthesized in four steps from acenaphthene. This seemingly simple molecule provides unique synthetic challenges because it is relatively difficult to reduce the nitro groups and the molecule contains a particularly reactive double bond. It was determined that the only feasible sequence for the synthesis was to nitrate acenaphthene, then brominate, eliminate, and finally selectively reduce. Several reduction methods were attempted before finding one that would completely reduce both nitro groups while leaving the double bond intact.

Self-assembly of lattices with high structural complexity from a geometrically simple molecule

Here we report an anomalous porous molecular crystal built of C–H···N-bonded double-layered roof-floor components and wall components of a segregatively interdigitated architecture. This complicated porous structure consists of only one type of fully aromatic multijoint molecule carrying three identical dipyridylphenyl wedges. Despite its high symmetry, this molecule accomplishes difficult tasks by using two of its three wedges for roof-floor formation and using its other wedge for wall formation. Although a C–H···N bond is extremely labile, the porous crystal maintains its porosity until thermal breakdown of the C–H···N bonds at 202°C occurs, affording a nonporous polymorph. Though this nonporous crystal survives even at 325°C, it can retrieve the parent porosity under acetonitrile vapor. These findings show how one can translate simplicity into ultrahigh complexity.

Pressure-induced emission band separation of the hybridized local and charge transfer excited state in a TPE-based crystal

We herein report a newly synthesized simple molecule, named TPEC4, with twisted D–A structure. TPEC4 showed two intrinsic emission bands ascribed to locally excited (LE) state and intramolecular charge transfer (ICT) state under high pressure.

Supramolecular chiroptical switching of helical-sense preferences through the two-way intramolecular transmission of a single chiral source

Complexation-induced reversal of helical-sense preferences is demonstrated with a simple molecule with a pair of exciton-coupled chromophores.