Steady-State and Time-Resolved Investigations on Pyrene-Based Chemosensors

Abstract

Two novel fluorescent probes bearing a single (P) and two (a podand-like structure, L) pyrene units derived from 1,5-bis(2-aminophenoxy)-3-oxopentane have been synthesized and investigated in dioxane using UV-vis absorption, and steady-state and time-resolved (in a picosecond time scale) emission spectroscopy; in the gas phase, matrix-assisted laser desorption ionization mass spectrometry was employed. In dioxane, the absorption and emission spectra of P present a unique band with maxima at 361 and 392 nm, which have been associated with the monomer absorption and emission bands, respectively. In dioxane, for compound L, an additional band with a maximum at ∼525 nm is observed; upon the addition of water, an emissive band (with maxima varying from 405 to 490 nm) appears in both P and L spectra; this is discussed in terms of the emission of a species with charge character. Upon metal addition (Cu(2+), Zn(2+), and Ag(+)) to P, a gradual quenching effect of the monomer emission is observed and found to be more pronounced with Cu(2+). In the case of L, upon the addition of metal cations, the long emission band (∼550 nm) decreases and the monomer emission band increases (with an isoemissive point at ∼450 nm) and no evidence for the intermediate band (at ∼405-490 nm) now exists. Time-resolved data in dioxane/water mixtures showed that for P and L these two fit double- and triple-exponential decay laws, respectively. With P, this has been attributed to a two-state system, which involves the monomer and a charged species, with its emission maxima varying with the polarity of the media (here mirrored by its dielectric constant), which can potentially be addressed to an exciplex-like species, whereas with L, it has been attributed to a three-state system involving, in addition to these two species, an excimer. From absorption and fluorescence excitation and time-resolved data, evidence is given for the presence of intramolecular dimer formation in the ground state.

From yellow to pink using a fluorimetric and colorimetric pyrene derivative and mercury (II) ions

“…Following our previous research with pyrene units [40], we have recently reported a single pyrene probe compound containing a fluorescent flexible dye [41]. Upon addition of metal ions, shows different colours from its yellow initial, such as, dark red for Cu 2+ , red orange for Zn 2+ and gold yellow for Ag + , thus allowing a direct visual differentiation and detection between these metal ions [41]. It is also worthy to report a recent study where an azide derivative of pyrene has shown to demonstrate a catalytic hydrolysis (to the aldehyde derivatives) upon addition of Hg 2+…”

Spectroscopic and photophysical studies of a naphthalene-based emissive probe for metal cations

“…This changes can be caused by different mechanisms such as photoinduced electron or charge transfer (PET or PCT) [6,7], excimer or exciplex formation [8][9][10], fluorescence resonance energy transfer (FRET) [11], internal charge transfer (ICT) [12,13], excited state intramolecular proton transfer (ESIPT) [14,15], etc [16]. 2+ ions has increasingly attracted the attention of several scientific fields [17] in particular medicine and environment [18].…”

Synthesis, Characterization, and Ion Sensing Application of Pyrene‐Containing Chemical Probes

“…Pyrene‐containing macromolecular structures have attracted a great deal of attention to be employed in fluorescent probes due to their long fluorescence lifetime and a well‐defined fluorescence spectrum, which is sensitive to the polarity of the environment . There are numerous studies in the literature on the fluorescence sensor applications of pyrene‐containing molecular compounds and high‐molecular polymers toward various analytes, including nitroaromatic compounds, metal ions, anions, and glucose …”

“…[1][2][3] While some ionic species are essential to sustain growth, they may act as harmful pollutants in the environment. [ 4 ] As an example, compounds, [ 16,17 ] metal ions, [ 14,[18][19][20][21] anions, [ 22,23 ] and glucose. [ 24 ] Chemosensors are chemical compounds which can respond to the changes in their chemical environment when it binds to a guest counterpart by altering their electrical, electronic, magnetic, or optical signal.…”