Part A. Accelerated curing of aryl-ethynyl end-capped polyimides. Part B. Catalytic pockets assembled by ion-pairing.

摘要

Part A. A series of end-cap model compounds were synthesized to determine the effect of modification of the aryl-ethynyl end-cap on the thermal curing process. Using 1H NMR and SEC, an accelerated thermal cure was discovered by replacement of the terminal phenyl group with 1-naphthyl- and 9-anthracenyl-ethynyl moiety. The acceleration (phenyl naphthyl anthracenyl) is in direct contrast to the steric bulk about the ethynyl bond (phenyl naphthyl anthracenyl). The acceleration discovered between phenyl- and naphthyl-model compounds occurs without a decrease in E_a, suggesting a difference in parameter(s) accounted for in A as the source of the acceleration. The thermal curing products of all model compounds are of approximately dimeric/trimeric structure with no higher products formed even towards complete reaction. The insoluble 2-naphthyl-analogue and the phenyl-control were studied using FTIR. The 2-naphthyl-model compound cures slightly faster, but with higher E_a, than the control phenyl-analogue. The analogous naphthyl- and anthracenyl-end-capped oligomers were synthesized and studied using DSC. The rate acceleration is also observed for the oligomers, resulting in a fast curing material. Analysis of the crystal structure and molecular mechanics of the model compounds reveals no significant differences in bond lengths or dipole moments, but a calculation of hyperpolarizability reveals an increase in the same order of the thermal cure trend (phenyl naphthyl anthracenyl). Incorporation of additional ether linkages in the backbone significantly effects the properties of the oligomers and resulting resins, but the rate acceleration using aryl-ethynyl end-caps are still observed and relatively unaffected by the backbone. Aryl-ethynyl model compounds incorporating electronic substituents were studied using SEC. An additional rate acceleration is observed by the incorporation of an electron-donating methoxy-substituent para to the ethynyl unit. The electron-withdrawing cyano-substituent has no effect. The analogous methoxy-naphthyl-ethynyl end-capped oligomer cure fits second-order kinetics best, unlike all other model compounds and oligomers studied, which demonstrate first-order kinetics. POSS monomers were incorporated into aryl-ethynyl end-capped oligomers and verified by NMR and SEC, and the resulting oligomers were found to undergo thermal cure to afford a new inorganic/organic hybrid resin. The new resins are also easily modified for fast-curing kinetics by incorporation of the new, fast-curing aryl-ethynyl end-caps.; Part B. Improved synthetic methods were used in the synthesis of 2,9-bis(aryl)- and 2,9-bis(arylethynyl)-1,10-phenanthroline ligands, including an unsymmetrical ligand. Further synthesis results in dianionic ligands for use in ion-pairing. The palladium complexes of 2,9-bis(aryl)- and 2,9-bis(arylethynyl)-1,10-phenanthroline ligands suffer from a cyclometallation reaction and a coordination shift, respectively, resulting in unsymmetrical complexes. The rhodium complexes of 2,9-bis(arylethynyl)-1,10-phenanthroline however, were found to be incredibly soluble and symmetric. Solution ion-pairing through proton transfer was accomplished and verified using 1H NMR. No enhanced optical rotations were observed between the 1:1 ion-pair and a 2:1 ion-pair control. A copper (I) complex was synthesized from the ion-paired ligand and confirmed by UV-visible spectroscopy and elemental analysis. Neutral and dicationic polymer-supported diamines were synthesized and the latter used in the formation of an ion-pair through ion-exchange. The polymer-supported ion-paired ligand was confirmed using FTIR. A resulting rhodium complex was also confirmed by FTIR and demonstrated catalytic activity in a benchmark hydrogenation reaction, in which the catalytic activity is intimately involved with the polymer-support.