The aromaticityantiaromaticity of substituted cyclopentadienyl derivatives has been measured using energetic magnetic and structural criteria to take into account the multidimensional character of aromaticity

Furthermore, the Euclidean distance values (d(j)) for all compounds have been estimated using the neural network developed previously. It has been demonstrated that the d(j) as a scale of aromaticity overcomes the particular limitations of the ASE, Lambda, NICS and HOMA indices to describe the changes in the aromaticity of cyclopentadiene ring due to substituent effects. Additionally, it is shown that neural networks are useful tools for establishing structure-property relationships. The results indicate that mostly the aromaticity of cyclopentadiene ring and cyclopentadienyl anion ring decrease upon substitution irrespective of the electronic character of the substituent. The electron-donating groups, especially hydroxyl groups, destabilize carbanion to a larger extent than electron-accepting ones. On the other hand, all the substituents reduce strongly the antiaromaticity of the cyclopentadienyl cation.

These results can be useful for the design of new cationic ligands with lowered instability and new cyclopentadienyl ligands with improved stability and 3D global aromaticity in a fully conjugated diradicaloid cage at different Aromaticity is a vital concept that governs the electronic properties of π-conjugated organic molecules and has long been restricted to 2D systems. The aromaticity in 3D π-conjugated molecules has been rarely studied. Here we report a fully conjugated diradicaloid molecular cage and its global aromaticity at different oxidation states. The neutral compound has an open-shell singlet ground state with a dominant 38π monocyclic conjugation pathway and follows the [4n + 2] Hückel aromaticity rule; the dication has a triplet ground state with a dominant 36π monocyclic conjugation pathway and satisfies [4n] Baird aromaticity; the tetracation is an open-shell singlet with 52 π-electrons that are delocalized along the 3D rigid framework, showing 3D global antiaromaticity; and the hexacation possesses D3 symmetry with 50 globally delocalized π-electrons, showing [6n + 2] 3D global aromaticity. Different types of aromaticity were therefore accessed in one molecular cage platform, depending on the symmetry, number of π-electrons and spin state.Structure, aromaticity, stability, and energetic performance of the analogues s-heptazine is one of the most attractive polycyclic C-N precursors for graphitic carbon nitride materials (CNx). In this paper in order to find the relationships between the structure, aromaticity, and stability for this novel compound, its analogues with three conjoint six-membered rings (I∼V) and derivatives with different substituents (VI-1∼VI-5) were investigated using the density functional theory method.

Aromaticity was predicted using the magnetic criterion iso-chemical shielding surface in the Z direction (ICSSzz) obtained with the gauge-independent atomic orbital (GIAO) method. Stability was estimated by the band gap and the topological properties obtained from the atoms in molecules theory. Results show that replacement of the CH groups with the nitrogen atoms in the tricyclic core enhances both the aromaticity and the stability. s-heptazine (VI) that has the maximum number of N atoms among analogues I∼VI possesses the largest aromaticity and the best stability. Substitutions of -NH2, -NHNH2, and -N3 groups increase not only the aromaticity but also the stability; -NO2 increases the aromaticity while decreases the stability; -CN decreases both the aromaticity and the stability. Furthermore, the energetic performance of VI-1∼VI-5 was evaluated according to the estimated specific impulse (Is). The obtained Is has the order of VI-5>VI-4>VI-3>VI>VI-1>VI-2.

The Is of VI-5 is higher than that of HMX (1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetraazacyclooctane).Current state of aromatics production using yeast: achievements and challenges.Technology, Kemivägen 10, Gothenburg SE-412 96, Sweden; Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg Technology, Kemivägen 10, Gothenburg SE-412 96, Sweden; Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg SE-412 96, Sweden; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark; BioInnovation Institute, Ole Maaløes vej 3, DK2200 Copenhagen N, Denmark. Electronic address: Aromatics find a range of applications in the chemical, food, cosmetic and pharmaceutical industries. While UV-Activated Acid Generator of aromatics on the current market heavily relies on petroleum-derived chemical processes or direct extraction from plants, there is an increasing demand for establishing new renewable and sustainable sources of aromatics. To this end, microbial cell factories-mediated bioproduction using abundant feedstocks comprises a highly promising alternative to aromatics production. In this review, we provide the recent development of de novo biosynthesis of aromatics derived from the shikimate pathway in yeasts, including the model Saccharomyces cerevisiae as well as other non-conventional species.