Pyrenyl Derivative with a Four-Atom Linker That Can Probe the Local Polarity of Pyrene-Labeled Macromolecules

Abstract

The fluorescent probe 1-pyrene­methoxy­ethanol (PyMe­EGOH) was designed to replace commercially available 1-pyrene­butanol (PyButOH) as an alternative fluorescent label to probe the internal dynamics and interior polarity of macro­molecules by steady-state and time-resolved fluorescence. While excimer formation and sensitivity to solvent polarity are two well-recognized properties of pyrene, much less known is that these properties are often mutually exclusive when a 1-pyrene­butyl derivative is used to prepare pyrene-labeled macro­molecules (PyLMs). As the sensitivity of pyrene to solvent polarity is a result of its symmetry, attaching a butyl group to pyrene breaks the symmetry of pyrene, so that the 1-pyrene­butyl derivatives are much less sensitive to the polarity of their environment compared to unmodified pyrene. This report demonstrates that replacement of a methylene group in the β-position of PyButOH by an oxygen atom, such as in PyMe­EGOH, restores the sensitivity of this pyrene derivative to the polarity of its local environment to the same level as that of molecular pyrene without impeding pyrene excimer formation upon incorporation into PyLMs.

Strong and Reversible Circularly Polarized Luminescence Emission of a Chiral 1,8‐Naphthalimide Fluorophore Induced by Excimer Emission and Orderly Aggregation

“…One is a monomer emission peak at around 382 nm due to the 1,8‐naphthalimide groups and the other is broad peak at around 482 nm, which can be regarded as an excimer emission from the 1,8‐naphthalimide groups . Upon the addition of water, R , R / S , S ‐ 2 initially showed polarity‐induced fluorescence enhancement in THF/H 2 O mixtures . However, when the water fraction was over 80 %, the emission intensity of R , R / S , S ‐ 2 exhibits a fluorescence quenching response behavior with a 62 nm bathochromic shift for the monomer emission peak at a 95 % water fraction.This can be attributed to the aggregation formation of the 1,8‐naphthalimide groups.…”

“…[9] Upon the addition of water, R,R/S,S-2 initially showed polarity-induced fluorescencee nhancement in THF/H 2 Om ixtures. [10] However,w hen the water fraction was over 80 %, the emission intensity of R,R/ S,S-2 exhibits af luorescence quenching response behavior with a6 2nmb athochromic shift for the monomer emission peak at a9 5% water fraction.Thisc an be attributedt ot he aggregation formation of the 1,8-naphthalimide groups. As is evident from Figure 1c,w hich shows the fluorescences pectra of R,R/S,S-2 in various solvents, R,R/S,S-2 exhibit clear enhancement in the excimer emission upon changing the solventf rom THF to MeOH.…”

Probing Side Chain Dynamics of Branched Macromolecules by Pyrene Excimer Fluorescence

“…The fluorescence decays were fitted globally according to the Fluorescence Blob Model (FBM). [15][16][17]20,21 The quality of the fits was assessed from the χ Figure 1 demonstrates that increasing the spacer length of the pyrene derivative from three atoms in PyEG0-MA to 12 atoms in PyEG3-MA substantially increased the efficiency of pyrene excimer formation. However this conclusion needs to be adjusted to account for the differences in vibrational structure experienced by the pyrene labels in different polymeric constructs.…”

“…Random copolymerization: The pyrene-labeled poly(butyl methacrylate)s (Py-PBMA) were prepared by radical copolymerization of PyEG0MA, PyEG1MA, PyEG2MA, or PyEG3MA with butyl methacrylate (BMA) to yield PyEGx-PBMA with x = 0 -3 (structures shown in Table 1) according to a procedure that was developed earlier. 20,21 The synthesis and purification of the PyEGx-PBMA samples with x = 1 has been described in detail earlier and the same procedure was applied to prepare the PyEGx-PBMA samples with x = 0, 2, and 3. absorption detectors was used. The quality and purity of the fluorescently labeled samples, particularly the confirmation that no free pyrene-labeled monomer eluting with the solvent remained in the polymer sample, was achieved by visual inspection of the traces of the DRI and UV-Vis absorption detectors.…”

Self-aggregation of the pyrene labeled poly(acrylic acid) in nanoscopically crowded environments

“…In water, PI equals 1.87, whereas in n-hexane it is 0.6 [46]. PI is also valid for pyrenyl derivatives containing heteroatoms like nitrogen or oxygen in the b-position to fluorophore [2,11,47]. In bulk water of pH = 3.4, the emission spectrum of PAAPy has a PI value of 1.64 (see Table 1).…”