Experimental and Theoretical Investigation of Intrinsic Pyridine Isomer Effects on Physical Property Tuning of Metallo Supramolecular Polymers Bearing Multiple Pyridine Ligands

Abstract

Coordinative polymers have gained great attention over the last two decades because of the potential versatile modification and functionalization of their physical properties. The pyridine isomer effects on metallo-supramolecular materials, where metal salts are blended with the polymers bearing pyridine coordinative ligands, have been frequently argued based only on steric effects. Here the pyridine isomer effects are investigated by both experimental and computational approaches. In the experimental approach, ZnCl 2 was blended with amorphous polyesters uniformly bearing either 4-vinylpyridine (4VP)-or 2vinylpyridine (2VP)-type ligands at the side groups. In addition, a polyester bearing both ligand types was also used to prepare blends with ZnCl 2 , which enabled deeper understanding of the pyridine isomer effects on the pyridine−metal coordination. Experimental characterizations by Fourier transform infrared spectroscropy, differential scanning calorimetry, and rheological measurements first revealed that the coordination of ZnCl 2 occurs more predominantly on 4VP ligands. Such pyridine isomer effects on the coordination are further investigated by density functional theory computation for complexes of ZnCl 2 with side chain models of 4VP or 2VP. On the basis of the obtained complex structures and stabilities, ZnCl 2 -complexation with two 4VP units was energetically more favored than for those with two 2VP units or 4VP/2VP mixtures. The coordination preference of the 4VP to ZnCl 2 was also confirmed by the stabilization of the interaction between the natural bond orbitals of the Zn-pyridyl N pair. Therefore, the theoretical approach can be applied to demonstrate the experimentally found unique isomeric effects of pyridine on metallo-supramolecular matrix, which will bring important insights into the practical application of coordinative polymers.

One‐Pot Synthesis of Dual Supramolecular Associative PMMA‐Based Copolymers and the Precise Thermal Property Tuning

“…In the spectrum of Neat‐10, the signal at 1604 cm –1 originates from the CN group of free pyridine. [ 16–18 ] The intensity of this signal gradually decreased upon addition of the metal salt, whereas a new peak was observed at 1621 cm –1 in the spectra of the blends. This new peak is attributed to the coordinated pyridine groups.…”

“…This new peak is attributed to the coordinated pyridine groups. [ 16–18 ] The decrease of the free pyridine peak was accompanied by a gradual intensity increase in the new peak at 1621 cm –1 , which indicates that the fraction of coordinated pyridine groups increased. A similar behavior regarding the coordination bond formation was observed for the Blend‐20‐ X series (Figure S7, Supporting Information).…”

“…Another class of supramolecular association, metal–ligand coordination, possesses higher association strength, which is more effective for enhancing the thermal property. [ 15–18 ] In addition, the molecular design utilizing dual supramolecular association has attracted attention for a more drastic modification of physical properties of materials. [ 19–21 ] Nevertheless, the synthesis and purification of the target dual supramolecular associative polymers for these systems require complicated multisteps, [ 19,22,23 ] which needs to be solved for further development of dual supramolecular associative materials.…”

Hybrid cellulose-poly(4-vinylpyridine) adsorbents produced via ATRP and their application to target polyphenols in winemaking, olive oil production and almond processing residues

“…Additionally, nitrogen containing polymers, especially those based on vinylpyridine monomers [6], present enhanced adsorption capabilities towards specific compounds, which justifies their use for the tailoring of some kinds of advanced materials. Indeed, due to their chelating capability, 4-vinylpyridine based materials are being considered for heavy metals adsorption with applications in wastewater/industrial effluents treatment [7][8][9][10], enzymes/protein adsorption [11,12] and other applications involving biomedicine or catalysis [13].…”

Tautomeric and Aggregational Dynamics of Curcumin-Supersaturated Pluronic Nanocarriers

“…Density functional theory (DFT) is an important computational approach often used to understand complex systems, molecular structure calculations, vibrational frequencies, molecular orientation, and interaction energies. − DFT deals with correlation energies and demonstrates advantages over the Moller–Plesset disturbance theory (MP2) method, as it requires less computational time to evaluate large chemical structures. Based on its abundant applicability, DFT has become a standard model for the study of large systems, especially in the solid state. , Recently, interaction mechanisms between metallic complexes and polymers have been studied in gas and aqueous phases. , Additionally, DFT proved effectiveness in the evaluation of the exothermic process in the adsorption of 5-fluorouracil, 6-mercaptopurine, and 6-thioguanine drugs in hexagonal boron nitride . The B3LYP functional, used in this work, includes a set of three adjusted parameters, which are responsible for mixing the “pure” DFT contributions to the Hartree–Fock (HF) exchange energy.…”