Ostrowski Sławomir, Jarończyk Małgorzata, Dobrowolski Jan Cz
Institute of Nuclear Chemistry and Technology 16 Dorodna-Street 03-195 Warsaw Poland
National Medicines Institute 30/34 Chełmska Str. 00-725 Warsaw Poland.
RSC Adv. 2025 Jul 10;15(29):24019-24030. doi: 10.1039/d5ra02589c. eCollection 2025 Jul 4.
Some 8-hydroxyquinolines (8-HQs) and some of their metal complexes are bioactive. Thus, knowing whether the ligand properties are transferred to the complex is vital. Herein, the aromaticity of the pyridine and phenolic rings of substituted 8-HQs, free with and without intramolecular H-bond and chelated in Re(i) complexes, was studied using the geometrical HOMA and magnetic INICS indices. The 8-HQs were substituted in every position with BH, CN, C[triple bond, length as m-dash]CH, Cl, and NH groups of diversified σ- and π-electron donor-acceptor properties. In the H-bonded 8-HQs, the BH and NH groups stabilize different positions. The stabilization pattern is similar for the non-H-bonded 8-HQs but quite different in the Re(i) complex. The HOMA and INICS values of the pyridine and phenolic rings show that they are geometrically and magnetically aromatic irrespective of the substituent type, substituent location, H-bond presence, or complex formation. Forming or breaking the O-H⋯N intramolecular H-bond does not essentially affect the two types of aromaticity. In contrast, chelating the Re(i) system with 8-HQ changes both so that the aromaticity of the H-bonded and chelated systems does not correlate. Hence, the aromaticity of the 8-HQ rings is not transferred from the free ligand to the complex with Re(i). Additionally, for H-bonded 8-HQs, the geometrical and magnetic aromaticity do not correlate, but a weak correlation trend can be observed for the complex.
一些8-羟基喹啉（8-HQ）及其金属配合物具有生物活性。因此，了解配体性质是否传递到配合物至关重要。在此，使用几何HOMA和磁性INICS指数研究了取代的8-HQ的吡啶环和酚环的芳香性，这些8-HQ在有无分子内氢键的情况下处于游离状态，并在Re（i）配合物中螯合。8-HQ的每个位置都被具有不同σ-和π-电子供体-受体性质的BH、CN、C≡CH、Cl和NH基团取代。在形成氢键的8-HQ中，BH和NH基团稳定不同的位置。对于未形成氢键的8-HQ，稳定模式相似，但在Re（i）配合物中则有很大不同。吡啶环和酚环的HOMA和INICS值表明，无论取代基类型、取代基位置、氢键的存在与否或配合物的形成情况如何，它们在几何和磁性上都是芳香性的。形成或断裂O-H⋯N分子内氢键基本上不会影响这两种芳香性。相反，用8-HQ螯合Re（i）体系会同时改变这两种芳香性，使得形成氢键的体系和螯合体系的芳香性不相关。因此，8-HQ环的芳香性不会从游离配体传递到与Re（i）形成的配合物中。此外，对于形成氢键的8-HQ，几何芳香性和磁性芳香性不相关，但在配合物中可以观察到微弱的相关趋势。
