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Muthamma K, Acharya S, Sunil D, Shetty P, Abdul Salam AA, Kulkarni SD, Anand PJ. Fluorene-naphthalene Schiff base as a smart pigment in invisible ink with multiple security features for advanced anticounterfeiting and forensic applications. J Colloid Interface Sci 2024; 653:209-219. [PMID: 37713919 DOI: 10.1016/j.jcis.2023.09.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/27/2023] [Accepted: 09/06/2023] [Indexed: 09/17/2023]
Abstract
Smart functional materials with captivating optical properties are of immense importance due to their versatile applicability in anticounterfeiting and forensic science. A fluorene-naphthalene Schiff base (FNH) that displays aggregation induced emission, mechanofluorochromism and excitation wavelength dependent fluorescence inherent to the pristine and ground samples is synthesized. Water/solvent-based invisible security inks for flexo/screen printing were formulated using FNH as a smart pigment to check the originality of documents/branded products etc. The prints with good photostability, adherence to substrate and rub resistance are invisible in daylight showcasing multiple non-destructive and destructive techniques to authenticate the document. The inked area on UV dull paper substrate exhibits a weak emission, which is observed by the forger under UVA light. However, the user can validate the authenticity of the document by rubbing the print with hard objects, especially using a metal coin or glass rod to perceive a human eye detectable intensification in the orange fluorescence under the same illumination source. The intensity of the orange fluorescence reverts to the original, which enables the reuse of the security document after originality check. Yet another nondestructive authentication method is to observe a cyan fluorescence from the print and orangish yellow fluorescence from the rubbed printed region when shined with a 270-400 nm light source, whereas a cyanish green fluorescence both from the unrubbed and rubbed regions of the print when illuminated with a visible light source ranging from 420 to 480 nm. An additional verification through a destructive technique is to perceive red and yellow fluorescence of the ink film upon contact with THF and NaOH/KOH, respectively and a penetrating red fluorescence from the rear side of the THF-exposed printed area of the paper. The multi-level security features that cannot be easily replicated by the forger but allows a simple and easy validation process by the user are unique to FNH, used as a single pigment in the inks. Further, the applicability of the ground FNH in forensic science is established to distinctly observe Level I to II details of latent fingerprints.
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Affiliation(s)
- Kashmitha Muthamma
- Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Sudarshan Acharya
- Department of Atomic & Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Dhanya Sunil
- Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India.
| | - Prakasha Shetty
- Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Abdul Ajees Abdul Salam
- Department of Atomic & Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Suresh D Kulkarni
- Department of Atomic & Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - P J Anand
- Manipal Technologies Limited, Manipal, Karnataka 576104, India
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Ngounoue Kamga FA, Hrubaru MM, Enache O, Diacu E, Draghici C, Tecuceanu V, Ungureanu EM, Nkemone S, Ndifon PT. Ni(II)-Salophen-Comprehensive Analysis on Electrochemical and Spectral Characterization and Biological Studies. Molecules 2023; 28:5464. [PMID: 37513334 PMCID: PMC10384438 DOI: 10.3390/molecules28145464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/03/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
New aspects of the Ni(II)-salophen complex and salophen ligand precursor were found during deep electrochemical and optical characterization, as well as biological studies for new pharmacological applications. Physicochemical and spectroscopic methods (1H- and 13C-NMR, FT-IR and UV-Vis, electrospray ionization mass spectroscopy, thermogravimetric analysis, and molar conductance measurements) were also used to prove that the salophen ligand acts as a tetradentate and coordinates to the central metal through nitrogen and oxygen atoms. The electrochemical behavior of the free Schiff salophen ligand (H2L) and its Ni(II) complex (Ni(II)L) was deeply studied in tetrabutylammonium perchlorate solutions in acetonitrile via CV, DPV, and RDE. Blue films on the surfaces of the electrodes as a result of the electropolymerization processes were put in evidence and characterized via CV and DPV. (H2L) and Ni(II)L complexes were tested for their antimicrobial, antifungal, and antioxidant activity, showing good antimicrobial and antifungal activity against several bacteria and fungi.
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Affiliation(s)
- Francis Aurelien Ngounoue Kamga
- Coordination Chemistry Laboratory, Department of Inorganic Chemistry, Faculty of Science, University of Yaounde 1, Yaounde P.O. Box 812, Cameroon
- Faculty of Chemical Engineering and Biotechnologies, University "Politehnica" of Bucharest, Gheorghe Polizu 1-7, Sector 1, 011061 Bucharest, Romania
| | - Madalina-Marina Hrubaru
- Faculty of Chemical Engineering and Biotechnologies, University "Politehnica" of Bucharest, Gheorghe Polizu 1-7, Sector 1, 011061 Bucharest, Romania
- "C. D. Nenitzescu" Institute of Organic and Supramolecular Chemistry, Romanian Academy, Sector 6, Spl. Independentei 202B, 060023 Bucharest, Romania
| | - Oana Enache
- Faculty of Chemical Engineering and Biotechnologies, University "Politehnica" of Bucharest, Gheorghe Polizu 1-7, Sector 1, 011061 Bucharest, Romania
| | - Elena Diacu
- Faculty of Chemical Engineering and Biotechnologies, University "Politehnica" of Bucharest, Gheorghe Polizu 1-7, Sector 1, 011061 Bucharest, Romania
| | - Constantin Draghici
- "C. D. Nenitzescu" Institute of Organic and Supramolecular Chemistry, Romanian Academy, Sector 6, Spl. Independentei 202B, 060023 Bucharest, Romania
| | - Victorita Tecuceanu
- "C. D. Nenitzescu" Institute of Organic and Supramolecular Chemistry, Romanian Academy, Sector 6, Spl. Independentei 202B, 060023 Bucharest, Romania
| | - Eleonora-Mihaela Ungureanu
- Faculty of Chemical Engineering and Biotechnologies, University "Politehnica" of Bucharest, Gheorghe Polizu 1-7, Sector 1, 011061 Bucharest, Romania
| | - Stephanie Nkemone
- Coordination Chemistry Laboratory, Department of Inorganic Chemistry, Faculty of Science, University of Yaounde 1, Yaounde P.O. Box 812, Cameroon
| | - Peter T Ndifon
- Coordination Chemistry Laboratory, Department of Inorganic Chemistry, Faculty of Science, University of Yaounde 1, Yaounde P.O. Box 812, Cameroon
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Rigamonti L, Forni A, Righetto S, Pasini A. Push–pull unsymmetrical substitution in nickel(ii) complexes with tetradentate N2O2 Schiff base ligands: synthesis, structures and linear–nonlinear optical studies. Dalton Trans 2019; 48:11217-11234. [DOI: 10.1039/c9dt01216h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Push–pull unsymmetrical substitution efficiently modulates the electronic, linear and nonlinear optical properties of nickel(ii) complexes with salen-type ligands.
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Affiliation(s)
- Luca Rigamonti
- Dipartimento di Scienze Chimiche e Geologiche
- Università degli Studi di Modena e Reggio Emilia
- 41125 Modena
- Italy
- Dipartimento di Chimica
| | - Alessandra Forni
- Istituto di Scienze e Tecnologie Molecolari
- Consiglio Nazionale delle Ricerche (ISTM-CNR)
- 20133 Milano
- Italy
- Dipartimento di Chimica
| | - Stefania Righetto
- Dipartimento di Chimica
- Università degli Studi di Milano
- 20133 Milano
- Italy
| | - Alessandro Pasini
- Dipartimento di Chimica
- Università degli Studi di Milano
- 20133 Milano
- Italy
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