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We show that the diradicaloid triangulene, a graphene nano-flake molecule, can aggregate in a variety of dimerization modes. We found by density functional theory modeling a number of triangulene dimers including six doubly bonded σ-dimers in addition to the previously reported six pancake bonded π-dimer isomers. The σ-dimers display a wide range of stabilities: the interaction energy of the most stable σ-dimer is -25.17 kcal mol . Besides the doubly bonded σ-dimers with closed shell ground states, we also found an open-shell singly σ-bonded diradicaloid dimer. We found an interesting isomerization route between a doubly bonded σ-dimer, a singly bonded σ-dimer with a low-lying triplet state and two π-bonded dimers with low-lying quintet states. Derivatives of triangulene, trioxo-triangulenes (TOTs) have been previously characterized experimentally. Here, we show the reasons why so far only the π-dimer but not the σ-dimer was experimentally observed for all TOTs.
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http://dx.doi.org/10.1002/chem.201705763 | DOI Listing |
Dalton Trans
September 2025
Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan.
A computational study at the M06-2X-D3/def2-TZVP level elucidates the [2 + 2] cycloaddition between phenylacetylene and G15-Rea ((L: → G15G15 ← :L)), featuring a doubly bonded G15G15 moiety (G15 = a group 15 element) and highlighting an electron-sharing interaction between two triplet G15 fragments. Among the systems examined, only dipnictogen dications containing SbSb and BiBi double bonds readily undergo [2 + 2] cycloaddition with phenylacetylene. Energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) and frontier molecular orbital (FMO) analyses reveal that the key bonding interaction in the reaction involves electron donation from the filled p-π orbital of PhCCH into the vacant p-π* orbital of G15-Rea, while the reverse electron transfer is only marginal.
View Article and Find Full Text PDFDalton Trans
September 2025
University of Patras, Department of Chemistry, 26504 Patras, Greece.
With the aim of assessing the role and impact of pseudohalides on the molecular and supramolecular structures of copper(II)/heavily substituted imidazole complexes, the synthesis and characterization of the complexes {[Cu(N)(HL)]} (1), {[Cu{N(CN)}(HL)]·MeCO} (2·MeCO) and [Cu(NCO)(HL)]·MeCN (3·MeCN) have been carried out; HL is the 4,5-diphenylimidazole ligand. The organic molecule behaves as a monodentate ligand through the pyridine-type nitrogen atom of the imidazole ring. The 1D polymer 1 is made up of undulating {-Cu-(N)-Cu-(N)-} chains, with the HL ligands extending from both sides of the chains.
View Article and Find Full Text PDFJ Am Chem Soc
August 2025
Department of Chemistry, University of Manchester, Manchester M13 9PL, U.K.
We report the deletion of nitrogen atoms from multiple template sites in rotaxanes, catenanes, and a molecular knot. Nitrogen extrusion from secondary amines in the backbone of the interlocked structures is achieved using -diphenylphosphinylhydroxylamine (DPPH), forming carbon-carbon bonds while largely maintaining the integrity of the original mechanical bonding. We find that DPPH gives improved yields (up to 51%) for nitrogen atom deletions from template sites in rotaxanes compared to an anomeric amide nitrogen-deletion reagent and overcomes a major substrate limitation in that, using DPPH, only one of the substituents of the secondary amine in the rotaxane axle needs to be radical-stabilizing.
View Article and Find Full Text PDFJ Phys Chem A
August 2025
Institut fur Chemie, Physikalische und Theoretische Chemie, Universitat Rostock, Albert-Einstein-Stra e 27, D-18059 Rostock, Germany.
Strong, local, and directional hydrogen bonds (HBs) govern the structures and arrangements of carboxy-functionalized ionic liquids. The analysis of infrared spectra in the CO stretching region has revealed doubly hydrogen-bonded cationic dimers (c=c) in the liquid, resembling the archetype HB motif known from carboxylic acids. The like-charge doubly hydrogen-bonded ion pairs are also present in the crystal structure, surviving the phase transition into the liquid state, and are still present in (2,1) complexes in the gas phase.
View Article and Find Full Text PDFChem Commun (Camb)
September 2025
Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
We report the first example of transmembrane anion transport mediated by a hydrogen-bonding homo[2]catenane. The catenane outperforms its non-interlocked analogues in chloride transport, highlighting the advantages of interlocked architectures in ionophore design. The synthesis of this electroneutral [2]catenane was enabled by doubly charged sulfate (SO), acting as a powerful anionic template.
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