Modulation of Excited‐State Proton‐Transfer Dynamics inside the Nanocavity of Microheterogeneous Systems: Microenvironment‐Sensitive Förster Energy Transfer to Riboflavin

Abstract

The excited‐state proton‐transfer efficiency of a tetraarylpyrene derivative, 1,3,6,8‐tetrakis(4‐hydroxy‐2,6‐dimethylphenyl)pyrene (TDMPP), was investigated thoroughly in the presence of various surfactant assemblies, such as micelles and vesicles. The confined microheterogeneous environments can significantly retard the extent of the excited‐state proton‐transfer process, resulting in a distinguishable optical signal compared to that in the bulk medium. Physical characteristics of the surfactant assemblies, such as order, interfacial hydration, and surface charge, influence the proton transfer process and allow multiparametric sensing. A higher degree of interfacial hydration facilitates the proton‐transfer process, while the positively charged head groups of the surfactants specifically stabilize the anionic form of the probe (TDMPP−O*). Furthermore, Forster energy transfer from the probe to riboflavin was studied in a phospholipid membrane, wherein the relative ratio of the neutral versus anionic forms (TDMPP‐OH/TDMPP−O*) was found to influence the extent of energy transfer. Overall, we demonstrate how an ultrafast photophysical process, that is, the excited‐state proton transfer, can be influenced by the microenvironment.

Improved Analytical Performance of an Amphiphilic Probe upon Protein Encapsulation: Spectroscopic Investigation along with Computational Rationalization

“…33−35 Pyrene has been chosen as the fluorophore of interest due to notable characteristics, including large photostability, long fluorescence decay time, and a propensity to dimerize and self-associate (formation of excimers). 36,37 However, the possible photoinduced electron transfer from the pyrenylic nitrogen (PyCH 2 -N) to the excited pyrenyl (Py*) chromophore is expected to lead to a quenching of emission since the deactivation of the excited state will proceed through a radiationless process. 38 However, owing to three primary nitrogen centers, bpa-based fluorescence probes have often been employed in constructing several sensors for transition metal ions and pH.…”

“…The molecule under consideration here is a bifunctional PET sensor, (1-pyrenyl)­methyl-bis-[(2-pyridyl)­methyl]­amine ( Pybpa ), composed of two distinct modules, bispicolyl as a binding site and pyrene as the signaling moiety. The compound was synthesized in a facile manner by coupling pyrenylmethyl chloride with the metal ion binding bis-[(2-pyridyl)­methyl]­amine ( bpa ) unit. − Pyrene has been chosen as the fluorophore of interest due to notable characteristics, including large photostability, long fluorescence decay time, and a propensity to dimerize and self-associate (formation of excimers). , However, the possible photoinduced electron transfer from the pyrenylic nitrogen (PyCH 2 - N ) to the excited pyrenyl (Py*) chromophore is expected to lead to a quenching of emission since the deactivation of the excited state will proceed through a radiationless process . However, owing to three primary nitrogen centers, bpa -based fluorescence probes have often been employed in constructing several sensors for transition metal ions and pH. , Such recovery of fluorescence signal via metal ion/ H + coordination is often termed chelation-enhanced fluorescence (CHEF).…”

Monitoring Local pH of Membranous Aggregates via Ratiometric Color Changing Response

“…[14] Thus, at this condition, we can expect formation of micellar structures, where the central hydrocarbon core is surrounded by stern layer (for ionic micelles) or palisade layer (for neutral micelles) containing head group of the surfactants and tightly-bound water molecules. [15] At pH 7.4, compound 1 showed orange color both in buffered medium and in presence of neutral and/or cationic micelles. However, the color changed to red in the presence of anionic micelle.…”

Construction of a novel fluorescent probe for sensitive determination of glyphosate in food and imaging living cells

“…The red-shi phenomenon suggested that the probe was susceptible to intramolecular charge transfer when bound to Cu 2+ , and the appearance of absorption bands at 500 nm and 520 nm may be attributed to intramolecular charge transfer interactions. [49][50][51] As the concentration of Cu 2+ increases, the uorescence intensity at 500 nm slowly decreased and CCU was dynamically responsive to the concentrations of Cu 2+ in the…”