Fluorescence of Syndiotactic Polystyrene/Trimethylbenzene Clathrate and Intercalate Co-Crystals

Abstract

The self-assembling of fluorescent guest molecules, with the δ nanoporous host crystalline phase of syndiotactic polystyrene (s-PS) films, reduces chromophore diffusivity. Moreover, the chromophore fluorescence can be largely perturbed by formation of suitable polymer co-crystals. In particular, by excitation at the absorbance maximum (≈265 nm), s-PS/1,3,5-trimethylbenzene clathrate co-crystals present a broad fluorescence band nearly centered at 300 nm, while the corresponding intercalate co-crystals present a red-shifted fluorescence band with maxima at 330, 340, and 355 nm. This red shifted fluorescence is possibly due to absorption of the primary fluorescence by ground state complexes, formed in the intercalate co-crystal. The enhanced and red-shifted fluorescence could be relevant for optical and optoelectronic applications.

Advanced materials based on polymer cocrystalline forms

“…On the other hand, for applications requiring a long‐term stability of the cocrystals, like for instance for films including active guests (e.g., fluorescent, photoreactive, etc. )131–138 low diffusivity a ∥ c ∥ uniplanar orientation should be most suitable.…”

“…Transparent films exhibiting polymer/chromophore cocrystalline phases can be easily prepared for s‐PS 131, 132, 167, 168…”

Characterization of Syndiotactic Polystyrene Nanofilms by PM‐IRRAS Spectroscopy

“…The nanoporous crystalline δ‐form can easily be transformed into co‐crystalline forms with active molecules and the formation of co‐crystals with relevant fluorescent, photoreactive, ferroelectric, magnetic, and antimicrobial guest molecules have been reported in the literature. Classical transmission spectroscopic measurements have shown for several molecules that after absorption in the δ‐form and formation of a co‐crystalline phase, significant perturbations of the guest molecule vibrational spectrum can take place .…”

“…It also allows controlling the orientation of the guest molecules not only in the microscopic crystalline phase but also in macroscopic films. On these bases, films presenting s‐PS/active‐guest cocrystalline phases have been proposed as advanced materials, mainly as optical (chromophore, fluorescent, photoreactive), ferroelectric, and paramagnetic materials. Moreover, for the δ and ϵ nanoporous phases, the three different kinds of uniplanar orientations can be helpful to control guest diffusivity .…”

Sulfonated syndiotactic polystyrene: sorption of ionic liquid in the amorphous phase and of organic guests in the crystalline phase

“…In particular, for s‐PS, two nanoporous crystalline phases (δ and ε) have been discovered, which can absorb several guest molecules producing clathrate and intercalate co‐crystals. Films presenting s‐PS/active‐guest co‐crystals have been proposed as advanced materials for optical, magnetic, and ferroelectric applications.…”