{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,19]],"date-time":"2025-10-19T18:28:49Z","timestamp":1760898529820,"version":"build-2065373602"},"reference-count":49,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2020,6,15]],"date-time":"2020-06-15T00:00:00Z","timestamp":1592179200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001711","name":"Schweizerischer Nationalfonds zur F\u00f6rderung der Wissenschaftlichen Forschung","doi-asserted-by":"publisher","award":["200020_182000"],"award-info":[{"award-number":["200020_182000"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The synthesis and structural characterization of 5,6\u2032-dimethyl-2,2\u2032-bipyridine (5,6\u2032-Me2bpy) are reported, along with the preparations and characterizations of [Cu(POP)(5,6\u2032-Me2bpy)][PF6] and [Cu(xantphos)(5,6\u2032-Me2bpy)][PF6] (POP = bis(2-(diphenylphosphanyl)phenyl)ether, xantphos = 4,5-bis(diphenylphosphanyl)-9,9-dimethyl-9H-xanthene). Single-crystal X-ray structure determinations of [Cu(POP)(5,6\u2032-Me2bpy)][PF6] and [Cu(xantphos)(5,6\u2032-Me2bpy)][PF6] confirmed distorted tetrahedral copper(I) coordination environments with the 5-methylpyridine ring of 5,6\u2032-Me2bpy directed towards the (C6H4)2O unit of POP or the xanthene unit of xantphos. In the xantphos case, this preference may be attributed to C\u2013H\u2026\u03c0 interactions involving both the 6-CH unit and the 5-methyl substituent in the 5-methylpyridine ring and the arene rings of the xanthene unit. 1H NMR spectroscopic data indicate that this ligand orientation is also preferred in solution. In solution and the solid state, [Cu(POP)(5,6\u2032-Me2bpy)][PF6] and [Cu(xantphos)(5,6\u2032-Me2bpy)][PF6] are yellow emitters, and, for powdered samples, photoluminescence quantum yields (PLQYs) are 12 and 11%, respectively, and excited-state lifetimes are 5 and 6 \u03bcs, respectively. These values are lower than PLQY and \u03c4 values for [Cu(POP)(6,6\u2032-Me2bpy)][PF6] and [Cu(xantphos)(6,6\u2032-Me2bpy)][PF6], and the investigation points to the 6,6\u2032-dimethyl substitution pattern in the bpy ligand being critical for enhancement of the PLQY.<\/jats:p>","DOI":"10.3390\/molecules25122760","type":"journal-article","created":{"date-parts":[[2020,6,16]],"date-time":"2020-06-16T00:50:49Z","timestamp":1592268649000},"page":"2760","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Positional Isomerism in the N^N Ligand: How Much Difference Does a Methyl Group Make in [Cu(P^P)(N^N)]+ Complexes?"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7536-2223","authenticated-orcid":false,"given":"Fabian","family":"Brunner","sequence":"first","affiliation":[{"name":"Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3631-5210","authenticated-orcid":false,"given":"Alessandro","family":"Prescimone","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4916-4041","authenticated-orcid":false,"given":"Edwin C.","family":"Constable","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8074-0089","authenticated-orcid":false,"given":"Catherine E.","family":"Housecroft","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,15]]},"reference":[{"key":"ref_1","unstructured":"Shaping Europe\u2019s digital future (2020, May 25). 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