{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,26]],"date-time":"2026-10-26T10:44:50Z","timestamp":1793011490580,"version":"4.5.0"},"reference-count":52,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,11,23]],"date-time":"2025-11-23T00:00:00Z","timestamp":1763856000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The crystal structures and vibrational spectra of 5-chloro-7-azaindole (5Cl7AI), 4,5-dichloro-7-azaindole (4,5Cl7AI), and 5-hydroxy-7-azaindole (5OH7AI) were investigated to elucidate how ring substituents modulate intermolecular hydrogen bonding and molecular packing in the solid state. Density functional theory (DFT) calculations were employed to support the interpretation of the spectroscopic data, while Hirshfeld surface analysis provided additional insight into intermolecular contacts. Single-crystal X-ray diffraction revealed that the halogenated derivatives form nearly linear N\u2013H\u00b7\u00b7\u00b7N hydrogen-bonded dimers or layered arrangements, whereas 5OH7AI adopts a three-dimensional network stabilized by N\u2013H\u00b7\u00b7\u00b7O and O\u2013H\u00b7\u00b7\u00b7N interactions. FT-IR and FT-Raman spectra showed that variations in hydrogen-bond topology strongly affect the N\u2013H and O\u2013H stretching regions: the halogenated derivatives exhibit broad, red-shifted bands (3300\u20132500 cm\u22121) characteristic of N\u2013H\u00b7\u00b7\u00b7N hydrogen bonds, while 5OH7AI displays smaller red shifts of the N\u2013H stretching bands accompanied by some additional features from O\u2013H stretching vibrations. DFT calculations at the B3LYP-D3 and \u03c9B97X-D levels reproduced the experimental geometries and vibrational spectra very well, providing detailed insight into the relationship between hydrogen-bond linearity, network dimensionality, and vibrational behavior.<\/jats:p>","DOI":"10.3390\/molecules30234525","type":"journal-article","created":{"date-parts":[[2025,11,24]],"date-time":"2025-11-24T13:09:25Z","timestamp":1763989765000},"page":"4525","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Hydrogen Bonding in Chloro- and Hydroxy-7-Azaindoles: Insights from X-Ray, Vibrational Spectroscopy, and DFT Studies"],"prefix":"10.3390","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6784-6401","authenticated-orcid":false,"given":"Karolina","family":"Dysz","sequence":"first","affiliation":[{"name":"Military Institute of Engineer Technology, Obornicka 136, 50-961 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3437-2043","authenticated-orcid":false,"given":"Julia","family":"B\u0105kowicz","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrze\u017ce Wyspia\u0144skiego 27, 50-370 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5431-9840","authenticated-orcid":false,"given":"Ksenia","family":"Szmigiel-Bakalarz","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, Faculty of Science and Technology, Jan Dlugosz University in Czestochowa, Armii Krajowej 13\/15, 42-200 Czestochowa, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4795-9687","authenticated-orcid":false,"given":"Magdalena","family":"Rydz","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrze\u017ce Wyspia\u0144skiego 27, 50-370 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8628-7369","authenticated-orcid":false,"given":"Barbara","family":"Morzyk-Ociepa","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, Faculty of Science and Technology, Jan Dlugosz University in Czestochowa, Armii Krajowej 13\/15, 42-200 Czestochowa, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"441","DOI":"10.1021\/ar950135n","article-title":"The C\u2212H\u00b7\u00b7\u00b7O Hydrogen Bond:\u2009 Structural implications and supramolecular design","volume":"29","author":"Desiraju","year":"1996","journal-title":"Acc. 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