168643 20260217205612.0 doi 10.1039/d5dt02386f sideral 148062 ART-2026-148062 eng Polo, Alvaro Unveiling n → π* interactions: convergence of quantum crystallography and computational insights 2026 Access copy available to the general public Unrestricted We report the identification and characterization of a n → π* interaction between halide anions and a cationic purine nucleobase. Through a combined quantum crystallographic and computational approach, we demonstrate that perpendicular anion⋯(sp2)carbon contacts occur consistently at the C2 position of the purine nucleobase, with geometries and energies comparable to hydrogen bonds. High-resolution X-ray charge density analysis of 2[Br]·H2O confirms the existence of a bond path and an electron density depletion on C2, supporting a charge-transfer interaction. Complementary theoretical studies reveal a lone pair-to-π* orbital delocalization mechanism, with second-order NBO energies up to 6 kcal mol−1. The interaction persists with various anions, hydration levels, and C2 substitutions, highlighting its robustness and potential relevance in supramolecular chemistry. This study provides the experimental validation of an n → π* contact, supported by topological and electrostatic descriptors. info:eu-repo/grantAgreement/ES/DGA/E05-23R info:eu-repo/grantAgreement/ES/DGA/E42-23R info:eu-repo/grantAgreement/ES/MCIU-AEI-FEDER/PID2021-122406NB-I00 info:eu-repo/semantics/embargoedAccess All rights reserved http://www.europeana.eu/rights/rr-f/ info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion García-Orduña, Pilar (orcid)0000-0002-7063-1292 Echeverría, Jorge Sanz Miguel, Pablo J. Universidad de Zaragoza (orcid)0000-0002-8220-6031 2010 760 Universidad de Zaragoza Dpto. Química Inorgánica Área Química Inorgánica (2026), [8 p.] Dalton Trans. Dalton Transactions 1477-9226 972488 http://zaguan.unizar.es/record/168643/files/texto_completo.pdf Versión publicada info:eu-repo/date/embargoEnd/2026-12-19 2742912 http://zaguan.unizar.es/record/168643/files/texto_completo.jpg?subformat=icon icon Versión publicada info:eu-repo/date/embargoEnd/2026-12-19 oai:zaguan.unizar.es:168643 articulos driver 2026-02-17-20:49:25 ARTICLE