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Unexpected Emission Properties of a 1,8‐Naphthalimide Unit Covalently Appended to a Zn–Salophen
Author(s) -
Piccinno Martina,
Aragay Gemma,
Mihan Francesco Yafteh,
Ballester Pablo,
Dalla Cort Antonella
Publication year - 2015
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201500258
Subject(s) - chemistry , supramolecular chemistry , quenching (fluorescence) , fluorescence , photochemistry , photoinduced electron transfer , derivative (finance) , acceptor , covalent bond , förster resonance energy transfer , electron transfer , crystallography , organic chemistry , crystal structure , condensed matter physics , physics , quantum mechanics , financial economics , economics
We report the synthesis, characterization, and binding properties of a Zn–salophen complex, 1a , functionalized with a 1,8‐naphthalimide unit. Unexpectedly, the emission spectrum of 1a shows a remarkable quenching of the band assigned to the naphthalimide unit. To better understand this phenomenon, a supramolecular model system constituted by a symmetric Zn–salophen and a pyridyl derivative of 1,8‐naphthalimide, 1b·2a , was investigated. We propose the existence of a photoinduced energy transfer process between the naphthalimide (donor) and the salophen (acceptor) units in 1b·2a . A similar process must be operative in the covalent receptor 1a . Nevertheless, the results deriving from steady‐state fluorescence experiments do not rule out the occurrence of a photoinduced electron transfer process as alternative pathway for the quenching. We also describe the chemosensing properties of receptor 1a and the supramolecular system 1b·2a towards acetate. The nonsymmetrically substituted salophen receptor 1a only transduces the binding of the anion to the Zn metal center in significant spectroscopic changes in its absorption spectrum. On the other hand, we exploit the strong emission quenching experienced by the naphthalimide component in the supramolecular complex 1b·2a to detect anions (e.g. acetate) by means of a typical “turn‐on” fluorescent indicator displacement assay.