{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T06:55:45Z","timestamp":1792220145187,"version":"4.4.0"},"reference-count":87,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2019,11,1]],"date-time":"2019-11-01T00:00:00Z","timestamp":1572566400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003407","name":"Ministero dell\u2019Istruzione, dell\u2019Universit\u00e0 e della Ricerca","doi-asserted-by":"publisher","award":["n\/a"],"award-info":[{"award-number":["n\/a"]}],"id":[{"id":"10.13039\/501100003407","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Salen-type metal complexes have been actively studied for their nonlinear optical (NLO) properties, and push-pull compounds with charge asymmetry generated by electron releasing and withdrawing groups have shown promising results. As a continuation of our research in this field and aiming at solid-state features, herein we report on the synthesis of mononuclear copper(II) derivatives bearing either tridentate N2O Schiff bases L(a\u2212c)\u2212 and pyridine as the forth ancillary ligand, [Cu(La\u2212c)(py)](ClO4) (1a\u2013c), or unsymmetrically-substituted push-pull tetradentate N2O2 Schiff base ligands, [Cu(5-A-5\u2032-D-saldpen\/chxn)] (2a\u2013c), both derived from 5-substituted salicylaldehydes (sal) and the diamines (1R,2R)-1,2-diphenylethanediamine (dpen) and (1S,2S)-1,2-diaminocyclohexane (chxn). All compounds were characterized through elemental analysis, infrared and UV\/visible spectroscopies, and mass spectrometry in order to guarantee their purity and assess their charge transfer properties. The structures of 1a\u2013c were determined via single-crystal X-ray diffraction studies. The geometries of cations of 1a\u2013c and of molecules 2a\u2013c were optimized through DFT calculations. The solid-state NLO behavior was measured by the Kurtz\u2013Perry powder technique @1.907 \u00b5m. All chiral derivatives possess non-zero quadratic electric susceptibility (\u03c7(2)) and an efficiency of about 0.15\u20130.45 times that of standard urea.<\/jats:p>","DOI":"10.3390\/ma12213595","type":"journal-article","created":{"date-parts":[[2019,11,1]],"date-time":"2019-11-01T12:30:50Z","timestamp":1572611450000},"page":"3595","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":27,"title":["Solid-State Nonlinear Optical Properties of Mononuclear Copper(II) Complexes with Chiral Tridentate and Tetradentate Schiff Base Ligands"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9875-9765","authenticated-orcid":false,"given":"Luca","family":"Rigamonti","sequence":"first","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy"},{"name":"Dipartimento di Chimica, Universit\u00e0 degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5020-5544","authenticated-orcid":false,"given":"Alessandra","family":"Forni","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica, Universit\u00e0 degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy"},{"name":"Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche, via C. Golgi 19, 20133 Milano, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1781-0360","authenticated-orcid":false,"given":"Elena","family":"Cariati","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica, Universit\u00e0 degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gianluca","family":"Malavasi","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chimiche e Geologiche, Universit\u00e0 degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alessandro","family":"Pasini","sequence":"additional","affiliation":[{"name":"Dipartimento di Chimica, Universit\u00e0 degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,11,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1103\/PhysRevLett.5.303","article-title":"Coherence, Narrowing, Directionality, and Relaxation Oscillations in the Light Emission from Ruby","volume":"5","author":"Collins","year":"1960","journal-title":"Phys. Rev. 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