Dataset Information

Computational Studies of Dimerization of [n]-Cyclacenes.

ABSTRACT: Cyclacenes, C_4nH_2n, consist of n linearly fused benzene rings that are arranged to result in a closed nanohoop structure. Cyclacenes are thus the cyclic versions of acenes and have so far escaped synthesis. In order to estimate the tendency of [n]-cyclacenes (6 ≤ n ≤ 20) to undergo dimerization, which is assumed to be a major pathway of degradation under oxygen-free conditions, we here report the energy of dimerization as computed by density functional theory using spin-restricted, spin-unrestricted, and thermally assisted-occupation (TAO) formalisms. It is found that the energy of dimerization increases with increasing size of n but that this increase is not monotonic for the smaller members of the series. This is due to the combination of the cryptoannulenic effect and the inherent strain of the cyclacenes. The energy of dimerization of the largest member inspected, [20]-cyclacene, is -59.3 kcal/mol, while we expect it to converge to -46 kcal/mol for n → ∞ based on comparison with data obtained for acenes.

SUBMITTER: Somani A

PROVIDER: S-EPMC11345815 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Computational Studies of Dimerization of [n]-Cyclacenes.

Somani Ankit A Gupta Divanshu D Bettinger Holger F HF

The journal of physical chemistry. A 20240812 33

Cyclacenes, C4nH2n, consist of n linearly fused benzene rings that are arranged to result in a closed nanohoop structure. Cyclacenes are thus the cyclic versions of acenes and have so far escaped synthesis. In order to estimate the tendency of [n]-cyclacenes (6 ≤ n ≤ 20) to undergo dimerization, which is assumed to be a major pathway of degradation under oxygen-free conditions, we here report the energy of dimerization as computed by densi ...[more]

PMID: 39133933

Similar Datasets

Project description:A computational study on the structure and stability of different series of glyphosate (Glyph) dimers comprising nonionized (N) and zwitterionic structures (Z) for neutral monomers, followed by an analysis of energetics of Glyph dimerization process have been performed by means of quantum chemical calculations in different media. Optimized geometries for energy minima, as well as relative potential and free energies of the possible various conformers of each series of Glyph dimer were computed as a function of the medium at B3LYP-D3/6-311++G(2d,2p) level. The solvation model based on density (SMD) is employed for all solution phase computations. Non-ionized dimers (DN), anion-cation (AC) and either zwitterion-zwitterion (DZP and DZC) or non-ionized-phosphonate zwitterion (NZP) ionized neutral forms of Glyph dimer are predicted to exist in the gas phase and in solution in large contrast to Glyph monomers. The DZC dimer form exhibiting a centrosymmetric arrangement of two carboxylate zwitterion units was found to be the most stable dimer structure in all media. In aqueous solution, the DZP and AC dimer type structures are significantly stabilized by hydration. The tautomerisms between DZC, DZP and AC dimer type structures have been investigated in the gas phase and in solution. The DZC type structures are more prone to experience proton transfer in water than in the gas phase and in cyclohexane. The mechanism for the tautomerization process in neutral ionized Glyph dimers proceeds via two direct proton transfer paths: DZP ⇋ AC ⇋ DZC. Results show that solvents play a key role in modulating the energetics of the dimerization process of Glyph. Solvation in cyclohexane, favors the dimerization process however, hydration opposed it. In aqueous solution, the mechanism of the dimerization of Glyph from its phosphonate zwitterionic monomer form (ZP) could be described by a set of equilibria including direct proton transfer paths as follows: 2ZP ⇋ DZP ⇋ AC ⇋ DZC. According to our results, in aqueous solution, DZC Glyph dimers and their corresponding DZP and AC tautomers should be present in higher concentration than phosphonate zwitterionic Glyph monomers for high Glyph concentration, a fact that seems controversial in the literature.

Dataset Information

Computational Studies of Dimerization of [n]-Cyclacenes.

Publications

Computational Studies of Dimerization of [<i>n</i>]-Cyclacenes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets