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The electronic and vibrational spectra of benzonitrile cation, C6H5CN+ (BZN+), in the gas phase at low temperatures are reported. Measurements were carried out using a cryogenic ion trapping apparatus. The mid-infrared spectrum shows a strong CN stretch at 2130 ± 1 cm−1 (4.694 ± 0.002 µm). The electronic spectrum is reported in the range 5040–5750 Å. This covers the forbidden B2B2 ← X2B1 and allowed C2B1 ← X2B1 transitions. The spectrum is dominated by a broad absorption feature at wavelengths shorter than 5250 Å, with the strongest absorption located at 5140 Å. Experimental data are complemented with quantum chemical calculations carried out at the density functional theory and extended multi-configurational quasi-degenerate perturbation theory level. The spectroscopic results are discussed in the context of astronomical observations in the infrared and visible. [ABSTRACT FROM AUTHOR]

Pentalene (C8H6) and NN- and BB-bridged heterocyclic analogues (BN)4H6, derived by replacement of CC pairs with BN, are taken as  paradigms for tuning of ring-current (anti)aromaticity by variation of π charge, electronegativity and substitution pattern.  Ab initio calculation of maps for the π current density induced in these model systems by a perpendicular external magnetic field exhibits the full range of tropicity, from diatropic aromatic to nonaromatic to paratropic antiaromatic, with a ready rationalisation in terms of an orbital model.  Further calculations on systems of varying charge in which these motifs are embedded in extended PAH systems with naphthalene and phenanthrene 'clamps' show promise for switching between current patterns and related  opto-electronic properties. Particular sensitivity to charge is found for the experimentally accessible NN-bridged heteropentalene hybrids., (© 2025 Wiley‐VCH GmbH.)

The proposed AIBLHiCoS method predicts a given compound's pKa in aqueous solution from a single ab initio bond length only, after geometry optimization in the gas phase. Here we provide simple and predictive equations for naphthols and chemically similar biomolecules. Each linear equation corresponds to a High-Correlation Subset (HiCoS) that expresses the novel type of linear free energy relationship discovered here. The naphthol family exhibits a clear and strong relationship with the phenol family, with the "active" C-O bond always producing the highest correlations. The proposed method can isolate erroneous experiments and operate in non-aqueous solution and at different temperatures. Moreover, the existence of "active fragments" is demonstrated in a variety of sizable biomolecules for which the pKa is successfully predicted.