{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T03:28:25Z","timestamp":1774322905757,"version":"3.50.1"},"reference-count":47,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,2,28]],"date-time":"2021-02-28T00:00:00Z","timestamp":1614470400000},"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 new symmetric acyclic N,N\u2019-bis(1-pyrenyl) squaramide (H2L) functionalized with the pyrene moiety as a fluorogenic fragment has been designed and its ability to selectively detect specific anions and metals investigated. H2L selectively binds Cl\u2212 both in solution (DMSO 0.5% H2O and MeCN) and in the solid state, and allows to selectively detect Cu2+ in MeCN with the formation of a 2:1 metal-receptor complex, with a green intense emission appreciable by naked eye under the UV lamp. The H2L copper complex preserves its emission properties in the presence of Cl\u2212. The addition of basic anions (OH\u2212, CN\u2212, and F\u2212) up to 10 equivalents caused the deprotonation of the squaramide NHs and a dramatic change of the emission properties of the H2L copper complex.<\/jats:p>","DOI":"10.3390\/molecules26051301","type":"journal-article","created":{"date-parts":[[2021,2,28]],"date-time":"2021-02-28T20:43:32Z","timestamp":1614545012000},"page":"1301","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Switching-On Fluorescence by Copper (II) and Basic Anions: A Case Study with a Pyrene-Functionalized Squaramide"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3688-4464","authenticated-orcid":false,"given":"Giacomo","family":"Picci","sequence":"first","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jessica","family":"Milia","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5010-7370","authenticated-orcid":false,"given":"Maria Carla","family":"Aragoni","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0058-6406","authenticated-orcid":false,"given":"Massimiliano","family":"Arca","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Simon J.","family":"Coles","sequence":"additional","affiliation":[{"name":"National Crystallography Service, Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alessandra","family":"Garau","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8093-576X","authenticated-orcid":false,"given":"Vito","family":"Lippolis","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Riccardo","family":"Montis","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James B.","family":"Orton","sequence":"additional","affiliation":[{"name":"National Crystallography Service, Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Claudia","family":"Caltagirone","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"667","DOI":"10.1038\/nchem.2706","article-title":"A synthetic ion transporter that disrupts autophagy and induces apoptosis by perturbing cellular chloride concentrations","volume":"9","author":"Busschaert","year":"2017","journal-title":"Nat. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"246","DOI":"10.1039\/C2CC37468D","article-title":"Small neutral molecular carriers for selective carboxylate transport","volume":"49","author":"Haynes","year":"2013","journal-title":"Chem. Commun."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1398","DOI":"10.1016\/j.chempr.2019.02.027","article-title":"The Versatility of Squaramides: From Supramolecular Chemistry to Chemical Biology","volume":"5","author":"Marchetti","year":"2019","journal-title":"Chemistry"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"11066","DOI":"10.1039\/D0CC04090H","article-title":"Simple squaramide receptors for highly efficient anion binding in aqueous media and transmembrane transport","volume":"56","author":"Picci","year":"2020","journal-title":"Chem. Commun."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"10336","DOI":"10.1039\/C9NJ01548E","article-title":"Fluorescent squaramide ligands for cellular imaging and their encapsulation in cubosomes","volume":"43","author":"Lachowicz","year":"2019","journal-title":"New J. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1363","DOI":"10.1039\/C7CC08706C","article-title":"Fluorescent squaramides as anion receptors and transmembrane anion transporters","volume":"54","author":"Bao","year":"2018","journal-title":"Chem. Commun."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"7916","DOI":"10.1039\/D0SM01075H","article-title":"Glycosyl squaramides, a new class of supramolecular gelators","volume":"16","author":"Ramos","year":"2020","journal-title":"Soft Matter"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"8990","DOI":"10.1039\/C4TC01776E","article-title":"Polymerisable squaramide receptors for anion binding and sensing","volume":"2","author":"Manesiotis","year":"2014","journal-title":"J. Mater. Chem. C"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"7373","DOI":"10.1002\/chem.201400292","article-title":"Sulfate-Selective Recognition by Using Neutral Dipeptide Anion Receptors in Aqueous Solution","volume":"20","author":"Elmes","year":"2014","journal-title":"Chem. Eur. J."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"7190","DOI":"10.1039\/C6NJ01482H","article-title":"An ion pair receptor facilitating the extraction of chloride salt from the aqueous to the organic phase","volume":"40","author":"Zdanowski","year":"2016","journal-title":"New J. Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1437","DOI":"10.1021\/ol0474608","article-title":"Preparation, Solid-State Characterization, and Computational Study of a Crown Ether Attached to a Squaramide","volume":"7","author":"Frontera","year":"2005","journal-title":"Org. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"9154","DOI":"10.1021\/acs.inorgchem.5b01577","article-title":"Cooperatively Enhanced Ion Pair Binding with a Hybrid Receptor","volume":"54","author":"Kalenius","year":"2015","journal-title":"Inorg. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"11639","DOI":"10.1039\/C6DT02235A","article-title":"Cooperative binding and extraction of sodium nitrite by a ditopic receptor incorporated into a polymeric resin","volume":"45","author":"Ziach","year":"2016","journal-title":"Dalton Trans."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"9542","DOI":"10.1039\/C9SC02923K","article-title":"Ion-pair induced supramolecular assembly formation for selective extraction and sensing of potassium sulfate","volume":"10","author":"Jagleniec","year":"2019","journal-title":"Chem. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Prohens, R., Martorell, G., Ballester, P., and Costa, A. (2001). A squaramide fluorescent ensemble for monitoring sulfate in water. Chem. Commun., 1456\u20131457.","DOI":"10.1039\/b104172j"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.jphotochem.2017.05.001","article-title":"On the origin of chloride-induced emission enhancement in ortho substituted squaramides","volume":"344","author":"Danao","year":"2017","journal-title":"J. Photochem. Photobiol. A Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1633","DOI":"10.1039\/c3cc38767d","article-title":"Chloride sensing via suppression of excited state intramolecular proton transfer in squaramides","volume":"49","author":"Porel","year":"2013","journal-title":"Chem. Commun."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"5638","DOI":"10.1021\/ol402500q","article-title":"Colorimetric and Luminescent Sensors for Chloride: Hydrogen Bonding vs. Deprotonation","volume":"15","author":"Elmes","year":"2013","journal-title":"Org. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3983","DOI":"10.1021\/jo100104g","article-title":"N,N\u2032-Diarylsquaramides: General, High-Yielding Synthesis and Applications in Colorimetric Anion Sensing","volume":"75","author":"Rostami","year":"2010","journal-title":"J. Org. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"12792","DOI":"10.1039\/C6CC03888C","article-title":"The death of the Job plot, transparency, open science and online tools, uncertainty estimation methods and other developments in supramolecular chemistry data analysis","volume":"52","author":"Hibbert","year":"2016","journal-title":"Chem. Commun."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.1039\/C0CS00062K","article-title":"Determining association constants from titration experiments in supramolecular chemistry","volume":"40","author":"Thordarson","year":"2011","journal-title":"Chem. Soc. Rev."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3115","DOI":"10.1021\/jo202332h","article-title":"Recognition and Sensing of Biologically Relevant Anions in Alcohol and Mixed Alcohol\u2013Aqueous Solutions Using Charge Neutral Cleft-Like Glycol-Derived Pyridyl\u2013Amidothiourea Receptors","volume":"77","author":"Duke","year":"2012","journal-title":"J. Org. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2302","DOI":"10.1021\/jo035546t","article-title":"Conformational Preferences and Self-Template Macrocyclization of Squaramide-Based Foldable Modules","volume":"69","author":"Rotger","year":"2004","journal-title":"J. Org. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2138","DOI":"10.1039\/C4DT02893G","article-title":"Anion complexation, transport and structural studies of a series of bis-methylurea compounds","volume":"44","author":"Olivari","year":"2015","journal-title":"Dalton Trans."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1362","DOI":"10.1039\/C8CS00155C","article-title":"Multifunctional porous hydrogen-bonded organic framework materials","volume":"48","author":"Lin","year":"2019","journal-title":"Chem. Soc. Rev."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"919","DOI":"10.1021\/ja511403t","article-title":"Turning On Catalysis: Incorporation of a Hydrogen-Bond-Donating Squaramide Moiety into a Zr Metal\u2013Organic Framework","volume":"137","author":"McGuirk","year":"2015","journal-title":"J. Am. Chem. Soc."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4426","DOI":"10.1002\/anie.201200729","article-title":"Squaramides as Potent Transmembrane Anion Transporters","volume":"51","author":"Busschaert","year":"2012","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3622","DOI":"10.1039\/C4NJ00530A","article-title":"New aminotetrazole derivatives as hydrogen bonding catalysts. A green and selective oxidation of organosulphides with H2O2 in H2O","volume":"38","author":"Secci","year":"2014","journal-title":"New J. Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"17385","DOI":"10.1021\/acs.inorgchem.0c02696","article-title":"Diradical Character of Neutral Heteroleptic Bis(1,2-dithiolene) Metal Complexes: Case Study of [Pd(Me2timdt)(mnt)] (Me2timdt = 1,3-Dimethyl-2,4,5-trithioxoimidazolidine; mnt2\u2013 = 1,2-Dicyano-1,2-ethylenedithiolate)","volume":"59","author":"Aragoni","year":"2020","journal-title":"Inorg. Chem."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"9444","DOI":"10.1039\/D0NJ01605E","article-title":"Fast and easy conversion of ortho amidoaryldiselenides into the corresponding ebselen-like derivatives driven by theoretical investigations","volume":"44","author":"Nascimento","year":"2020","journal-title":"New J. Chem."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"336","DOI":"10.1021\/ml100097f","article-title":"[Au2(phen2Me)2(\u03bc-O)2](PF6)2, a Novel Dinuclear Gold(III) Complex Showing Excellent Antiproliferative Properties","volume":"1","author":"Cinellu","year":"2010","journal-title":"ACS Med. Chem. Lett."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3925","DOI":"10.1002\/ejic.202000665","article-title":"Water-Soluble Organotin Compounds\u2014Syntheses, Structures and Reactivity towards Fluoride Anions in Water","volume":"2020","author":"Alashkar","year":"2020","journal-title":"Eur. J. Inorg. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"14516","DOI":"10.1039\/c3dt51292d","article-title":"Zn2+\/Cd2+ optical discrimination by fluorescent chemosensors based on 8-hydroxyquinoline derivatives and sulfur-containing macrocyclic units","volume":"42","author":"Aragoni","year":"2013","journal-title":"Dalton Trans."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"10097","DOI":"10.1021\/jp105346h","article-title":"Role of the Substituent Effect over the Squarate Oxocarbonic Ring: Spectroscopy, Crystal Structure, and Density Functional Theory Calculations of 1,2-Dianilinosquairane","volume":"114","author":"Silva","year":"2010","journal-title":"J. Phys. Chem. A"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"899","DOI":"10.1021\/cr00088a005","article-title":"Intermolecular interactions from a natural bond orbital, donor-acceptor viewpoint","volume":"88","author":"Reed","year":"1988","journal-title":"Chem. Rev."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1080\/0144235X.2016.1192262","article-title":"What is NBO analysis and how is it useful?","volume":"35","author":"Weinhold","year":"2016","journal-title":"Int. Rev. Phys. Chem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1107\/S0108767307043930","article-title":"A short history of SHELX","volume":"64","author":"Sheldrick","year":"2008","journal-title":"Acta Crystallogr. Sect. A"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1107\/S0021889808042726","article-title":"OLEX2: A complete structure solution, refinement and analysis program","volume":"42","author":"Dolomanov","year":"2009","journal-title":"J. Appl. Crystallogr."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1107\/S2053229614024218","article-title":"Crystal structure refinement with SHELXL","volume":"71","author":"Sheldrick","year":"2015","journal-title":"Acta Crystallogr. Sect. C"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1107\/S2053273314026370","article-title":"SHELXT\u2014Integrated space-group and crystal-structure determination","volume":"71","author":"Sheldrick","year":"2015","journal-title":"Acta Crystallogr. Sect. A"},{"key":"ref_41","unstructured":"Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Petersson, G.A., and Nakatsuji, H. (2016). Gaussian 16 Rev. C.01, Gaussian Inc."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Koch, W., and Holthausen, M.C. (2001). A Chemist\u2019s Guide to Density Functional Theory, Wiley. [2nd ed.].","DOI":"10.1002\/3527600043"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"664","DOI":"10.1063\/1.475428","article-title":"Exchange functionals with improved long-range behavior and adiabatic connection methods without adjustable parameters: The mPW and mPW1PW models","volume":"108","author":"Adamo","year":"1998","journal-title":"J. Chem. Phys."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"3297","DOI":"10.1039\/b508541a","article-title":"Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy","volume":"7","author":"Weigend","year":"2005","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1057","DOI":"10.1039\/b515623h","article-title":"Accurate Coulomb-fitting basis sets for H to Rn","volume":"8","author":"Weigend","year":"2006","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"2999","DOI":"10.1021\/cr9904009","article-title":"Quantum Mechanical Continuum Solvation Models","volume":"105","author":"Tomasi","year":"2005","journal-title":"Chem. Rev."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1023\/A:1008193805436","article-title":"Molden: A pre- and post-processing program for molecular and electronic structures","volume":"14","author":"Schaftenaar","year":"2000","journal-title":"J. Comput. Aid. Mol. Des."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/26\/5\/1301\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:30:26Z","timestamp":1760160626000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/26\/5\/1301"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,2,28]]},"references-count":47,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2021,3]]}},"alternative-id":["molecules26051301"],"URL":"https:\/\/doi.org\/10.3390\/molecules26051301","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,2,28]]}}}