{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T04:41:31Z","timestamp":1770957691564,"version":"3.50.1"},"reference-count":27,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,9]],"date-time":"2021-02-09T00:00:00Z","timestamp":1612828800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"This research was supported by an Inha University Research Grant","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>\u03c0-Extended di-2-picolylamine (DPA)-substituted 8-hydroxyquinoline (8-HQ) tolans (2) were synthesized for testing electronic and regio-effects. The electron-poor CN-tolan (2b) showed clear selectivity for Cd2+ (&gt;&gt;Zn2+) over other metal ions via turn-on fluorescence, while the electron-rich MeO-tolan (2a) displayed no clear metal selectivity. Furthermore, considering that there was no significant energy difference between the Cd2+ complexes of 1 and 2b, the intended regio-effect (7- vs. 5-substituted effect) did not induce steric hindrance. Thus, the regio-effect is mainly electronic. Considering the above, 2a and 2b constitute a complete showcase in which electronic and regio-effects modulate the metal selectivity. The fluorescence titration of 2b (10 mM) with Cd2+ showed that the limit of detection (LOD) of the Cd2+-selective 2b was 158 nM in PBS (phosphate-buffered saline) (10 mM, pH 7.2) containing 50% MeOH.<\/jats:p>","DOI":"10.3390\/molecules26040917","type":"journal-article","created":{"date-parts":[[2021,2,14]],"date-time":"2021-02-14T02:08:12Z","timestamp":1613268492000},"page":"917","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Tuned Cd2+ Selectivity: Showcase of Electronic and Regio-Effect of \u03c0-Extended Di-2-Picolylamine-Substituted Quinoline-Based Tolans"],"prefix":"10.3390","volume":"26","author":[{"given":"Min-Sung","family":"Ko","sequence":"first","affiliation":[{"name":"Department of Chemistry and Chemical Engineering, Inha University, Inharo 100, Nam-gu, Incheon 22212, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"P. Sankara","family":"Rao","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Chemical Engineering, Inha University, Inharo 100, Nam-gu, Incheon 22212, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3272-0745","authenticated-orcid":false,"given":"Dong-Gyu","family":"Cho","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Chemical Engineering, Inha University, Inharo 100, Nam-gu, Incheon 22212, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"10712","DOI":"10.1039\/C9TA01846H","article-title":"\u03b2-Functionalized push\u2013pull opp-dibenzoporphyrins as sensitizers for dye-sensitized solar cells: The role of the phenylethynyl bridge","volume":"7","author":"Hu","year":"2019","journal-title":"J. Mater. Chem. 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