{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,29]],"date-time":"2025-12-29T04:49:40Z","timestamp":1766983780710,"version":"build-2065373602"},"reference-count":31,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2021,12,2]],"date-time":"2021-12-02T00:00:00Z","timestamp":1638403200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>Symmetrically substituted curcumin analogue compounds possess electron donor moieties at both ends of the conjugated systems; their difluoroboron complexes were synthesized, and their structures were fully characterized. A novel compound with enhanced photophysical properties bearing phenothiazine moieties is reported. The introduction of BF2 into the molecular structures resulted in bathochromic shifts both in the absorption and emission spectra, indicating that the \u03c0-conjugation was more extended than the one in the initial compounds. The solvatochromic effects were studied, which in case of the phenothiazinyl-curcumin BF2 complex was the most notable. Theoretical study of the investigated compounds was carried out using DFT and TD-DFT methods to evaluate the ground state geometries and vertical excitation energies.<\/jats:p>","DOI":"10.3390\/sym13122299","type":"journal-article","created":{"date-parts":[[2021,12,7]],"date-time":"2021-12-07T02:48:13Z","timestamp":1638845293000},"page":"2299","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Photophysical Properties and Electronic Structure of Symmetrical Curcumin Analogues and Their BF2 Complexes, Including a Phenothiazine Substituted Derivative"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4324-0787","authenticated-orcid":false,"given":"Emese","family":"G\u00e1l","sequence":"first","affiliation":[{"name":"Department of Chemistry and Chemical Engineering, Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany J\u00e1nos Street 11, RO-400028 Cluj-Napoca, Romania"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6356-6349","authenticated-orcid":false,"given":"Levente Csaba","family":"Nagy","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Chemical Engineering, Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany J\u00e1nos Street 11, RO-400028 Cluj-Napoca, Romania"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"10132","DOI":"10.1039\/C6RA25436E","article-title":"Influence of the electron donor groups on the optical and electrochemical properties of borondifluoride complexes of curcuminoid derivatives: A joint theoretical and experimental study","volume":"7","author":"Canard","year":"2017","journal-title":"RSC Adv."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5308","DOI":"10.1002\/anie.201107724","article-title":"Curcumin-from molecule to biological function","volume":"51","author":"Esatbeyoglu","year":"2012","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1016\/S0968-0896(00)82152-5","article-title":"Inhibition of the HIV-1 and HIV-2 proteases by curcumin and curcumin boron complexes","volume":"1","author":"Sui","year":"1993","journal-title":"Bioorg. Med. Chem."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1618","DOI":"10.1039\/C3OB42201A","article-title":"Syntheses and photophysical properties of BF2 complexes of curcumin analogues","volume":"12","author":"Bai","year":"2014","journal-title":"Org. Biomol. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"117126","DOI":"10.1016\/j.saa.2019.05.031","article-title":"Synthesis, photophysical and solvatochromic properties of diacetoxyboron complexes with curcumin derivatives","volume":"220","author":"Lyu","year":"2019","journal-title":"Spectrochim. Acta A Mol. Biomol. Spectrosc."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1016\/j.saa.2015.07.064","article-title":"Fluorescent difluoroboron-curcumin analogs: An investigation of the electronic structures and photophysical properties","volume":"152","author":"Margar","year":"2016","journal-title":"Spectrochim. Acta A Mol. Biomol. Spectrosc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1002\/adfm.200700697","article-title":"Fine-tuning of yellow or red photo- and electroluminescence of functional difluoro-boradiazaindacene films","volume":"18","author":"Bonardi","year":"2008","journal-title":"Adv. Funct. Mater."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1016\/j.ccr.2017.06.026","article-title":"Difluoroboron \u03b2-diketonate dyes: Spectroscopic properties and applications","volume":"350","author":"Chen","year":"2017","journal-title":"Coord. Chem. Rev."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1039\/c9pp00375d","article-title":"Curcumin derivatives as photosensitizers in photodynamic therapy: Photophysical properties and: In vitro studies with prostate cancer cells","volume":"19","author":"Kazantzis","year":"2020","journal-title":"Photochem. Photobiol. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"21501","DOI":"10.3390\/molecules201219772","article-title":"Synthesis and biological evaluation of curcumin derivatives with water-soluble groups as potential antitumor agents: An in vitro investigation using tumor cell lines","volume":"20","author":"Ding","year":"2015","journal-title":"Molecules"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"6300","DOI":"10.1002\/chem.201304897","article-title":"Molecular engineering of simple phenothiazine-based dyes to modulate dye aggregation, charge recombination, and dye regeneration in highly efficient dye-sensitized solar cells","volume":"20","author":"Hua","year":"2014","journal-title":"Chem. Eur. J."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"116189","DOI":"10.1016\/j.synthmet.2019.116189","article-title":"Phenothiazine-based derivatives for optoelectronic applications: A review","volume":"257","author":"Haque","year":"2019","journal-title":"Synth. Met."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1304","DOI":"10.1016\/j.cclet.2016.07.002","article-title":"Recent advances in phenothiazine-based dyes for dye-sensitized solar cells","volume":"27","author":"Luo","year":"2016","journal-title":"Chin. Chem. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2235","DOI":"10.1002\/cber.191304602149","article-title":"Studien \u00fcber Curcumin","volume":"46","author":"Lampe","year":"1913","journal-title":"Ber. Dtsch. Chem. Ges."},{"key":"ref_15","first-page":"280","article-title":"Curcumina e curcuminoidi","volume":"40","author":"Pavolini","year":"1950","journal-title":"Ann. Chim."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1002\/recl.19640830407","article-title":"A synthesis of curcumin and related compounds","volume":"83","author":"Pabon","year":"1964","journal-title":"Recl. Trav. Chim. Pays-Bas"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2264","DOI":"10.3762\/bjoc.13.223","article-title":"Curcuminoid-BF2 complexes: Synthesis, fluorescence and optimization of BF2 group cleavage","volume":"13","author":"Weiss","year":"2017","journal-title":"Beilstein J. Org. Chem."},{"key":"ref_18","first-page":"262","article-title":"Revisiting curcumin chemistry part I: A new strategy for the synthesis of curcuminoids","volume":"73","author":"Sudheer","year":"2011","journal-title":"Indian J. Pharm. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"820","DOI":"10.4172\/pharmaceutical-sciences.1000296","article-title":"Revisiting Curcumin Chemistry-Part II: Synthesis of Monomethylcurcumin and Isomeric Demethoxycurcumins and their Characterization","volume":"79","author":"Rao","year":"2017","journal-title":"Indian J. Pharm. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"854","DOI":"10.1016\/j.ejmech.2017.11.048","article-title":"Activation of anti-oxidant Nrf2 signaling by enone analogues of curcumin","volume":"143","author":"Deck","year":"2018","journal-title":"Eur. J. Med. Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3811","DOI":"10.1016\/j.bmc.2005.03.035","article-title":"Anti-oxidant activities of curcumin and related enones","volume":"13","author":"Weber","year":"2005","journal-title":"Bioorg. Med. Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1515\/hc-2015-0096","article-title":"Mechanochemical synthesis of 2,2-difluoro-4, 6-bis(\u03b2-styryl)-1,3,2-dioxaborines and their use in cyanide ion sensing","volume":"21","author":"Sherin","year":"2015","journal-title":"Heterocycl. Commun."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"4446","DOI":"10.1021\/jo400389h","article-title":"Synthesis and photophysical properties of difluoroboron complexes of curcuminoid derivatives bearing different terminal aromatic units and a meso-aryl ring","volume":"78","author":"Felouat","year":"2013","journal-title":"J. Org. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2070","DOI":"10.1016\/j.tetlet.2013.02.015","article-title":"BF3\u00b7OEt2-promoted concise synthesis of difluoroboron-derivatized curcumins from aldehydes and 2,4-pentanedione","volume":"54","author":"Liu","year":"2013","journal-title":"Tetrahedron Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.jfluchem.2016.09.009","article-title":"Fluoro-curcuminoids and curcuminoid-BF2adducts: Synthesis, X-ray structures, bioassay, and computational\/docking study","volume":"191","author":"Laali","year":"2016","journal-title":"J. Fluor. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"625","DOI":"10.1562\/0031-8655(2000)072<0625:EOSOTE>2.0.CO;2","article-title":"Effect of solvent on the excited-state photophysical properties of curcumin","volume":"72","author":"Khopde","year":"2000","journal-title":"Photochem. Photobiol."},{"key":"ref_27","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_28","unstructured":"Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Mennucci, B., and Petersson, G.A. (2009). Gaussian 09, Revision E.01, Gaussian, Inc."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jmgm.2017.10.022","article-title":"Metal chelating ability and antioxidant properties of Curcumin-metal complexes\u2014A DFT approach","volume":"79","author":"Mary","year":"2018","journal-title":"J. Mol. Graph. Modell."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"o860","DOI":"10.1107\/S160053680700222X","article-title":"Redetermination of curcumin: (1E,4Z,6E)-5-hydroxy-1,7-bis(4-hydroxy-3-methoxy-phenyl)hepta-1,4,6-trien-3-one","volume":"63","author":"Parimita","year":"2007","journal-title":"Acta Crystallogr. Sect. Sect. E Struct. Rep. Online"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1007\/s00214-019-2415-4","article-title":"Computational modeling of curcumin-based fluorescent probe molecules","volume":"138","author":"Satalkar","year":"2019","journal-title":"Theor. Chem. Acc."}],"container-title":["Symmetry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-8994\/13\/12\/2299\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:38:51Z","timestamp":1760168331000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-8994\/13\/12\/2299"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12,2]]},"references-count":31,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2021,12]]}},"alternative-id":["sym13122299"],"URL":"https:\/\/doi.org\/10.3390\/sym13122299","relation":{},"ISSN":["2073-8994"],"issn-type":[{"type":"electronic","value":"2073-8994"}],"subject":[],"published":{"date-parts":[[2021,12,2]]}}}