{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T04:52:08Z","timestamp":1772167928953,"version":"3.50.1"},"reference-count":31,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2020,1,10]],"date-time":"2020-01-10T00:00:00Z","timestamp":1578614400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100014440","name":"Ministerio de Ciencia, Innovaci\u00f3n y Universidades","doi-asserted-by":"publisher","award":["CTQ2017-84319-P, RED2018-102331-T and CTQ2017-85821-R"],"award-info":[{"award-number":["CTQ2017-84319-P, RED2018-102331-T and CTQ2017-85821-R"]}],"id":[{"id":"10.13039\/100014440","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>This manuscript reports the improved synthesis of the \u03b1,\u03b1,\u03b1,\u03b1 isomer of tetra-p-iodophenyl tetra-methyl calix[4]pyrrole and the X-ray characterization of two solvate polymorphs. In the solid state, the calix[4]pyrrole receptor adopts the cone conformation, including one acetonitrile molecule in its aromatic cavity by establishing four convergent hydrogen bonds between its nitrogen atom and the four pyrrole NHs of the former. The inclusion complexes pack into rods, displaying a unidirectional orientation. In turn, the rods form flat 2D-layers by alternating the orientation of their p-iodo substituents. The 2D layers stack on top of another, resulting in a head-to-head and tail-to-tail orientation of the complexes or their exclusive arrangement in a head-to-tail geometry. The dissimilar stacking of the layers yields two solvate polymorphs that are simultaneously present in the structures of the single crystals. The ratio of the two polymorph phases is regulated by the amount of acetonitrile added to the chloroform solutions from which the crystals grow. Halogen bonding interactions are highly relevant in the crystal lattices of the two polymorphs. We analyzed and characterized these interactions by means of density functional theory (DFT) calculations and several computational tools. Remarkably, single crystals of a solvate containing two acetonitrile molecules per calix[4]pyrrole were obtained from pure acetonitrile solution.<\/jats:p>","DOI":"10.3390\/molecules25020285","type":"journal-article","created":{"date-parts":[[2020,1,10]],"date-time":"2020-01-10T10:20:29Z","timestamp":1578651629000},"page":"285","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Synthesis, X-ray Characterization and Density Functional Theory (DFT) Studies of Two Polymorphs of the \u03b1,\u03b1,\u03b1,\u03b1, Isomer of Tetra-p-Iodophenyl Tetramethyl Calix[4]pyrrole: On the Importance of Halogen Bonds"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9307-8127","authenticated-orcid":false,"given":"Drago\u0219","family":"D\u0103buleanu","sequence":"first","affiliation":[{"name":"Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Avinguda Pa\u00efsos Catalans, 16, 43007 Tarragona, Spain"},{"name":"Departament de Qu\u00edmica Anal\u00edtica i Qu\u00edmica Org\u00e0nica, Universitat Rovira i Virgili, carrer Marcel\u2022li Domingo, 1, 43007 Tarragona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5793-781X","authenticated-orcid":false,"given":"Antonio","family":"Bauz\u00e1","sequence":"additional","affiliation":[{"name":"Departament de Qu\u00edmica, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8131-0315","authenticated-orcid":false,"given":"Joaqu\u00edn","family":"Ortega-Castro","sequence":"additional","affiliation":[{"name":"Departament de Qu\u00edmica, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eduardo C.","family":"Escudero-Ad\u00e1n","sequence":"additional","affiliation":[{"name":"Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Avinguda Pa\u00efsos Catalans, 16, 43007 Tarragona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pablo","family":"Ballester","sequence":"additional","affiliation":[{"name":"Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Avinguda Pa\u00efsos Catalans, 16, 43007 Tarragona, Spain"},{"name":"Catalan Institution of Research and Advanced Studies (ICREA), Passeig Llu\u00eds Companys, 23, 08018 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7840-2139","authenticated-orcid":false,"given":"Antonio","family":"Frontera","sequence":"additional","affiliation":[{"name":"Departament de Qu\u00edmica, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,1,10]]},"reference":[{"key":"ref_1","first-page":"1","article-title":"Review on Calix[4]Pyrrole: A versatile receptor","volume":"6","author":"Shah","year":"2019","journal-title":"Adv. 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