Syndiotactic Polystyrene Clathrates with Polar Guest Molecules

Abstract

Stable syndiotactic polystyrene (s-PS) co-crystals with highly polar guests have been prepared by sorption in δ or in co-crystalline phases of molecules dissolved in suitable solvent carriers. These co-crystals are clathrates, that is, isolated molecules are imprisoned as a guest into cavities formed between layers of polymer helices, and the maximum guest molecular volume is close to 0.25 nm3. Infrared linear dichroism measurements show that molecules included in s-PS molecular complexes are oriented nearly perpendicular to the chain axes of the polymeric crystalline phase. These new materials present in their crystalline phases an ordered three-dimensional arrangement of highly polar molecules with large first-order hyperpolarizability.

Highly efficient and selective reduction of nitroarenes into anilines catalyzed by gold nanoparticles incarcerated in a nanoporous polymer matrix: Role of the polymeric support and insight into the reaction mechanism

“…The reduction of p-chloro nitrobenzene (entry 6 of Table 3) needs longer reaction time (24 h) and affords the corresponding aniline in moderate selectivity. The interpretation of these data is not immediate since the reaction rate is affected by several factors, among which the diffusion of the reactant through the polymer matrix which in turn depends on both the polarity and the steric bulkiness of the guest molecule [33].…”

Polymer co-crystalline films for photonics

“…This different type of nanoporosity generally leads, in co-crystals obtained from the ε phase, to an orientation of the guest molecular planes parallel to the polymer host chain-axes [5] rather than perpendicular, as generally observed [15,16] for co-crystals from the δ phase. Moreover the channel-shaped cavities of the ε-form allows to obtain co-crystals with guest molecules much longer than those hosted by the δ "polymeric framework" [5].…”

“…In recent studies, it has been shown that the δ phase of sPS, although apolar, is able to absorb, from solutions in suitable carrier-solvents, high-polarity guests eventually leading to highly stable apolar-host/polar-guest clathrate phases [16]. This procedure allows the preparation of sPS co-crystals with high polarity guests like 4-nitro-aniline (µ = 6.2 D) having non-zero first order hyperpolarizability [16].…”

“…This procedure allows the preparation of sPS co-crystals with high polarity guests like 4-nitro-aniline (µ = 6.2 D) having non-zero first order hyperpolarizability [16].…”

“…This different dichroism is due to a different orientation of the pNA molecules with respect to the chain axis. From the dichroism values it is possible to determine the orientation of guest molecules with respect to the chain axis of the polymeric crystalline host [15,16] and in ε/pNA co-crystals the dipole moments of the pNA tend to be parallel to the polymer chain axes (see Figure 2(b), left) while in δ/pNA co-crystals the dipole moments tend to be perpendicular to the chain axes (see Figure 2(b), right).…”