{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T07:49:06Z","timestamp":1791013746203,"version":"4.1.0"},"reference-count":55,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2024,2,10]],"date-time":"2024-02-10T00:00:00Z","timestamp":1707523200000},"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 photophysical and sensory properties of the donor\u2013acceptor pyrazoloquinoline derivative (PQPc) were investigated using absorption, steady-state, and time-resolved fluorescence measurements. The compound synthesized from commercial, readily available substrates exhibited absorptions in the UV\u2013Vis range, with a maximum of the longwave band around 390 nm. The maximum fluorescence was around 460\u2013480 nm, depending on the solvent. The quantum yield was between 12.87% (for n-hexane) and 0.75% (for acetonitrile) and decreased with increasing solvent polarity. The PET mechanism was implicated as the cause of fluorescence quenching. Divalent ions such as Zn2+, Pb2+, Cd2+, Ca2+, Mg2+, Co2+, Ni2+, and Cu2+ were introduced to study the fluorescent response of PQPc. A 13-times increase in fluorescence quantum yield was observed after the addition of Zn2+ ions. Detailed research was carried out for the PQPc-Zn2+ system in order to check the possibility of analytical applications of PQPc as a fluorescent sensor. A detection limit of Zn2+ was set at the value level 1.93 \u00d7 10\u22127 M. PQPc-Zn2+ complexes had a stoichiometry of 1:1 with a binding constant of 859 M\u22121. Biological studies showed that the sensor was localized in cells near the membrane and cytoplasm and may be used to detect zinc ions in eukaryotic cells.<\/jats:p>","DOI":"10.3390\/molecules29040823","type":"journal-article","created":{"date-parts":[[2024,2,12]],"date-time":"2024-02-12T06:19:59Z","timestamp":1707718799000},"page":"823","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Fluorescent Sensor Based on 1H-Pyrazolo[3,4-b]quinoline Derivative for Detecting Zn2+ Cations"],"prefix":"10.3390","volume":"29","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3041-5368","authenticated-orcid":false,"given":"Anna","family":"Kolbus","sequence":"first","affiliation":[{"name":"Institute of Chemistry, The Jan Kochanowski University, Uniwersytecka 7 St., 25-406 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5511-0686","authenticated-orcid":false,"given":"Tomasz","family":"Uchacz","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry, Jagiellonian University, Gronostajowa 2 St., 30-387 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9790-1224","authenticated-orcid":false,"given":"Andrzej","family":"Danel","sequence":"additional","affiliation":[{"name":"Faculty of Materials Engineering and Physics, Cracow University of Technology, Podchor\u0105\u017cych St.1, 30-348 Krak\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7961-0503","authenticated-orcid":false,"given":"Katarzyna","family":"Ga\u0142czy\u0144ska","sequence":"additional","affiliation":[{"name":"Institute of Biology, The Jan Kochanowski University, Uniwersytecka 7 St., 25-406 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paulina","family":"Moskwa","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, The Jan Kochanowski University, Uniwersytecka 7 St., 25-406 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3838-5172","authenticated-orcid":false,"given":"Przemys\u0142aw","family":"Kolek","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Rzesz\u00f3w, 1 Pigonia St., 35-310 Rzesz\u00f3w, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,2,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"321","DOI":"10.3103\/S1068364X1408002X","article-title":"Microelements and the Organic System of Coal","volume":"57","author":"Admakin","year":"2014","journal-title":"Coke Chem."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Nieder, R., Benbi, D.K., and Reichl, F.X. (2018). Soil Components and Human Health, Springer.","DOI":"10.1007\/978-94-024-1222-2"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Kabata-Pendias, A., and Mukherjee, A.B. (2007). Trace Elements from Soil to Human, Springer.","DOI":"10.1007\/978-3-540-32714-1"},{"key":"ref_4","first-page":"144","article-title":"Zinc and its importance for human health: An integrative review","volume":"18","author":"Roohani","year":"2013","journal-title":"J. Res. Med. Sci."},{"key":"ref_5","unstructured":"Shils, M.E., Shike, M., Ross, A.C., Caballero, B., and Cousins, R.J. (2006). Modern Nutrition in Health and Disease, Lippincott Williams and Witkins. [10th ed.]."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"314","DOI":"10.18794\/aams\/63507","article-title":"Importance of zinc for the human body in the aspect of zinc supplementation","volume":"71","year":"2017","journal-title":"Ann. Acad. Med. Siles."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1152\/physrev.1993.73.1.79","article-title":"The biochemical basis of zinc physiology","volume":"73","author":"Vallee","year":"1993","journal-title":"Physiol. Rev."},{"key":"ref_8","unstructured":"Jarosz, M. (2012). Normy \u017bywienia dla Populacji Polskiej-Nowelizacja, Instytut \u017bywno\u015bci i \u017bywienia. (In Polish)."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1248\/yakushi.128.333","article-title":"Zinc deficiency and clinical practice-validity of zinc preparations","volume":"128","author":"Yanagisawa","year":"2008","journal-title":"Yakuga. Zasshi"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1111\/j.1365-3016.2012.01289.x","article-title":"Effect of zinc supplementation on pregnancy and infant outcomes: A systematic review","volume":"26","author":"Chaffee","year":"2012","journal-title":"Paediatr. Perinat. Epidemiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s00204-005-0009-5","article-title":"Zinc: A Multipurpose Trace Element","volume":"80","author":"Stefanidou","year":"2006","journal-title":"Arch. Toxicol."},{"key":"ref_12","unstructured":"U.S. Environmental Protection Agency (2023, November 13). Toxicological Review of Zinc and Compounds, Available online: https:\/\/iris.epa.gov\/static\/pdfs\/0426tr.pdf."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Valeur, B. (2002). Molecular Fluorescence. Principles and Applications, Willey-VCH Verlag GmbH.","DOI":"10.1002\/3527600248"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Balzani, V., Credi, A., and Venturipp, M. (2008). Molecular Devices and Machines. Concepts and Perspectives for the Nanoworld, Willey-VCH Verlag GmbH. [2nd ed.].","DOI":"10.1002\/9783527621682"},{"key":"ref_15","unstructured":"Prasanna de Silve, A. (2013). Molecular Logic-Based Computation, The Royal Society of Chemistry."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4017","DOI":"10.1002\/slct.202000662","article-title":"A Selective and Reversible Fluorescent Probe for Zn2+ Detection in living Cells","volume":"5","author":"Chen","year":"2020","journal-title":"ChemistrySelect"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1021\/acssensors.5b00022","article-title":"Reaction based Probes for Imaging mobile Zinc in Live Cells and Tissues","volume":"1","author":"Zastrow","year":"2016","journal-title":"ACS Sens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"13447","DOI":"10.1021\/ja072432g","article-title":"Development of an Iminocoumarin-Based Zinc Sensor Suitable for Ratiometric Fluorescence Imaging of Neuronal Zinc","volume":"129","author":"Komasu","year":"2007","journal-title":"J. Am. Chem. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"6555","DOI":"10.1021\/ja025567p","article-title":"Improvement and Biological Applications of Fluorescent Probes for Zinc, ZnAFs","volume":"124","author":"Hirano","year":"2002","journal-title":"J. Am. Chem. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1575","DOI":"10.1063\/1.1309016","article-title":"Sharp green electroluminescence from 1H-pyrazolo[3,4-b]quinoline-based light emitting diodes","volume":"77","author":"Tao","year":"2000","journal-title":"Appl. Phys. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4647","DOI":"10.1021\/ol027025i","article-title":"1,3-Diphenyl-1H-pyrazolo[3,4-b]quinoline; A versatile Fluorophore for the Design of Brightly Emissive molecular Sensors","volume":"4","author":"Rurack","year":"2002","journal-title":"Org. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1007\/s10895-010-0726-x","article-title":"A new fluorescent sesnor based on 1H-pyrazolo[3,4-b]quinoline skeleton. Part 2","volume":"21","author":"Mac","year":"2011","journal-title":"J. Fluoresc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"5110","DOI":"10.1039\/C9CS00318E","article-title":"F\u00f6rster resonance energy transfer (FRET)-based small-molecule sensors and imaging agents","volume":"49","author":"Wu","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"121449","DOI":"10.1016\/j.saa.2022.121449","article-title":"Substituent derivatives of benzothiazole-based fluorescence probes for hydrazine with conspicuous luminescence properties: A theoretical study","volume":"279","author":"Cao","year":"2022","journal-title":"Spectrochim. Acta A"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Cao, Y., Yu, X., Sun, C., and Cui, J. (2022). Theoretical Investigation on the ESIPT Process and Detection Mechanism for Dual-Proton Type Fluorescent Probe. Int. J. Mol. Sci., 23.","DOI":"10.3390\/ijms23042132"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"14417","DOI":"10.1021\/acsomega.8b01660","article-title":"Aggregation-Induced Emission-Based Fluorescence Probe for Fast and Sensitive Imaging of Formaldehyde in Living Cells","volume":"3","author":"Chen","year":"2018","journal-title":"ACS Omega"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Chen, Y. (2022). Recent Advances in Excimer-Based Fluorescence Probes for Biological Applications. Molecules, 27.","DOI":"10.3390\/molecules27238628"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"40842","DOI":"10.1039\/C7RA08142A","article-title":"Preparation of exciplex-based fluorescent organic nanoparticles and their application in cell imaging","volume":"7","author":"Wang","year":"2017","journal-title":"RSC Adv."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1039\/CS9922100187","article-title":"Molecular Fluorescent Signalling with \u2019Fluor-Spacer-Receptor\u2019 Systems: Approaches to Sensing and Switching Devices via Supramolecular Photophysics","volume":"21","author":"Bissell","year":"1992","journal-title":"Chem. Soc. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"9403","DOI":"10.1021\/ja051218u","article-title":"Molecular AND and INHIBIT gates based on control of porphyrin fluorescence by photochromes","volume":"127","author":"Straight","year":"2005","journal-title":"J. Am. Chem. Soc."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"6838","DOI":"10.1039\/D0CC00478B","article-title":"Fluorescent molecular logic gates based on photoinduced electron transfer (PET) driven by a combination of atomic and biomolecular inputs","volume":"56","author":"Wright","year":"2020","journal-title":"Chem. Commun."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"213598","DOI":"10.1016\/j.ccr.2020.213598","article-title":"Logical sensing with fluorescent molecular logic gates based on photoinduced electron transfer","volume":"426","author":"Magri","year":"2021","journal-title":"Coordin Chem. Rev."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Prasanna de Silva, A., Gunaratne, H.Q.N., and Maguire, G.E.M. (1994). \u2019Off-On\u2019 Fluorescent Sensors for Physiological levels of Magnesium Ions based on Photoinduced Electron Transfer (PET), which also behave as Photoionic OR Logic Gates. J. Chem. Soc. Chem. Commun., 1213\u20131214.","DOI":"10.1039\/C39940001213"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"625","DOI":"10.1016\/j.snb.2015.07.009","article-title":"Design and synthesis of a novel PET and ICT based 1,8-naphthalimide FRET bichromophore as a fourinput Disabled-Enabled-OR logic gate","volume":"221","author":"Georgiev","year":"2015","journal-title":"Sens. Actuat B-Chem."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Gunnlaugsson, T., Mac D\u00f3nail, D.A., and Parker, D. (2000). Luminescent molecular logic gates: The two-input inhibit (INH) function. Chem. Commun., 93\u201394.","DOI":"10.1039\/a908951i"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1293","DOI":"10.1039\/C4CC07891H","article-title":"A redox-activated fluorescence switch based on a ferrocene\u2013fluorophore\u2013boronic ester conjugate","volume":"51","author":"Li","year":"2014","journal-title":"Chem. Commun."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1016\/j.dyepig.2015.09.016","article-title":"Amino derivatives of 1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline\u2013Photophysics and implementation of molecular logic switches","volume":"124","author":"Uchacz","year":"2016","journal-title":"Dyes Pigment."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"527","DOI":"10.1016\/j.optmat.2017.02.063","article-title":"Photophysical properties of 6-N,N-dimethylpyrazolo[3,4-b]quinoline substituted with pyridyl in the 3-position","volume":"66","author":"Grabka","year":"2017","journal-title":"Opt. Mater."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"107511","DOI":"10.1016\/j.microc.2022.107511","article-title":"Recent advances in turn off-on fluorescence sensing strategies for sensitive biochemical analysis\u2014A mechanistic approach","volume":"179","author":"Huy","year":"2022","journal-title":"Microchem. J."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1207","DOI":"10.1007\/s10895-013-1251-5","article-title":"Applications of fluorescent sensor based on 1H-pyrazolo[3,4-b]quinoline in analytical chemistry","volume":"23","author":"Mac","year":"2013","journal-title":"J. Fluoresc."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"109713","DOI":"10.1016\/j.dyepig.2021.109713","article-title":"1H-Pyrazolo[3,4-b]quinoline derivative with the chelating substituent: Synthesis and spectral properties as fluorescent senor for cation detection","volume":"195","author":"Danel","year":"2021","journal-title":"Dyes Pigment."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1353","DOI":"10.1016\/S1872-1508(07)60071-0","article-title":"Validity and Reliability of Benesi-Hildebrand Method","volume":"23","author":"Wang","year":"2007","journal-title":"Acta Phys. -Chim. Sin."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1016\/j.jlumin.2016.11.057","article-title":"Off-on fluorescent sensor based on the bis(2,4,7,8,9-pentamethyldipyrrolylmethene-3-yl)methane for detection of Cd2+ and Hg2+ cations","volume":"183","author":"Bumagina","year":"2017","journal-title":"J. Lumin."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"108255","DOI":"10.1016\/j.dyepig.2020.108255","article-title":"Dual-functional chemosensor with colorimetric\/ratiometric response to Cu(II)\/Zn(II) ions and its applications in bioimaging and molecular logic gates","volume":"177","author":"He","year":"2020","journal-title":"Dyes Pigment."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1186\/1750-2187-5-5","article-title":"Zinc release from thapsigargin\/IP3-sensitive stores in cultured cortical neurons","volume":"5","author":"Stork","year":"2010","journal-title":"J. Mol. Signal."},{"key":"ref_46","first-page":"35","article-title":"Intracellular zinc distribution in mitochondria, ER and the Golgi apparatus","volume":"8","author":"Lu","year":"2016","journal-title":"Int. J. Physiol. Pathophysiol. Pharmacol."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Lakowicz, J.R. (2006). Principles of Fluorescence Spectroscopy, Springer. [3rd ed.].","DOI":"10.1007\/978-0-387-46312-4"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1016\/S0076-6879(82)87029-8","article-title":"[27] Determination of binding stoichiometry by the continuous variation method: The job plot","volume":"87","author":"Huang","year":"1982","journal-title":"Method. Enzymol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"A1133","DOI":"10.1103\/PhysRev.140.A1133","article-title":"Self-Consistent Equations Including Exchange and Correlation Effects","volume":"140","author":"Kohn","year":"1965","journal-title":"Phys. Rev."},{"key":"ref_50","unstructured":"Parr, R.G., and Yang, W. (1988). Density-Functional Theory of Atoms and Molecules, Oxford University Press."},{"key":"ref_51","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, Revision C.01, Gaussian Inc.. Available online: https:\/\/scholar.google.com\/scholar_lookup?title=Gaussian+16+Revision+A.03&author=Frisch,+M.J.&author=Trucks,+G.W.&author=Schlegel,+H.B.&author=Scuseria,+G.E.&author=Robb,+M.A.&author=Cheeseman,+J.R.&author=Scalmani,+G.&author=Barone,+V.&author=Petersson,+G.A.&author=Nakatsuji,+H.&publication_year=2016."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"3098","DOI":"10.1103\/PhysRevA.38.3098","article-title":"Density-functional exchange-energy approximation with correct asymptotic behavior","volume":"38","author":"Becke","year":"1988","journal-title":"Phys. Rev. A At. Mol. Opt. Phys."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"785","DOI":"10.1103\/PhysRevB.37.785","article-title":"Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density","volume":"37","author":"Lee","year":"1988","journal-title":"Phys. Rev. B Condens. Matter Mater. Phys."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1016\/0301-0104(81)85090-2","article-title":"Electrostatic interaction of a solute with a continuum. A direct utilizaion of AB initio molecular potentials for the prevision of solvent effects","volume":"55","author":"Scrocco","year":"1981","journal-title":"Chem. Phys."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1016\/0301-0104(82)85072-6","article-title":"Approximate evaluations of the electrostatic free energy and internal energy changes in solution processes","volume":"65","author":"Tomasi","year":"1982","journal-title":"Chem. Phys."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/29\/4\/823\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:58:27Z","timestamp":1760104707000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/29\/4\/823"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,2,10]]},"references-count":55,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2024,2]]}},"alternative-id":["molecules29040823"],"URL":"https:\/\/doi.org\/10.3390\/molecules29040823","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,2,10]]}}}