RT Journal Article
T1 Host/Guest Simulation of Fluorescent Probes Adsorbed into Low-Density Polyethylene, 1. Excimer Formation of 1,3-Di(1-pyrenyl)propane
A1 Pozuelo de Diego, Javier
A1 Dib Zambon Atvars, Teresa
A1 Bravo de Pedro, Julio
A1 Baselga Llidó, Juan
AB Molecular dynamics and Rotational Isomer State/Monte Carlo techniques with a Dreiding 1.01 Force Field are employed to study the excimer formation of isolated 1,3-di(1-pyrenyl)propane and the probe adsorbed into a low-density polyethylene (LDPE) matrix model. The probability of formation of each molecular conformer at several temperatures was calculated using these theoretical techniques. Conformational statistical analysis of the four torsion angles (ϕ₁, ϕ₂, θ₁, θ₂) of Py3MPy showed that the angles —C—Cᵃʳ— (ϕ₁, ϕ₂) present two states c ± = ±90°; and the angles —C—C— (θ₁, θ₂), the three trans states = 180°, g ± = ±60°. The correlation of θ₁–θ₂ torsion angles showed that the most probable pairs were g⁺g⁻ and g⁻g⁺ for the excimer-like specimens, although these angles are distorted because of interactions with the polymer matrix. The temperature dependence of the excimer-formation probability revealed that this process was thermodynamically controlled in the isolated case. When the probe was adsorbed into the LDPE matrix, the excimer formation process was reversed at T = 375 K. At T > 375 K, the behavior was similar to the isolated case but, at T < 375 K, excimer formation probability increased with temperature as found experimentally by steady-state fluorescence spectroscopy. This temperature was coincident with the onset of the LDPE melting process, determined experimentally by thermal analysis.
PB John Wiley & Sons, Inc.
SN 1022-1344
YR 2001
FD 2001-11
LK https://hdl.handle.net/10016/25876
UL https://hdl.handle.net/10016/25876
LA eng
NO The authors wish to thank Brite EuRam programme (BE97-4472) and CAM (07N/0002/1998) for support.
DS e-Archivo
RD 22 jun. 2024