Synthesis and Characterization of Conjugated Polyazines and Polyazomethines Containing the Thienylene Moiety and Flexible Hydrocarbon Side Chains

Abstract

Condensation reactions of mono- and didodecyl-substituted-2,5-diformylthiophene with hydrazine, p-diaminobenzene, 2,7-diaminofluorene, and 1,5-diaminonaphatalene give the corresponding polyazines (PAZs) and polyazomethines (PAMs), which have been characterized by thermal, structural, and optical analyses. The former polymers begin to decompose at 300 °C, while the latter polymers are stable up to 360 °C. All disubstituted polymers and the regioregular monosubstituted polyazines show nematic character. Disubstituted polymers display a larger conjugation with respect to monosubstituted ones. This effect has been attributed to a different conformation of thiophenic rings versus imino-linkages assumed by the polymeric backbone in the two classes of polyazines. Particular attention has been devoted to study the reactivity of mono- and disubstituted dialdehydes toward condensation with nucleophiles displaying different steric hindrance or power. Specifically the study of the reaction onset allowed us to determine the conditions to obtain regioregular monosubstituted polymers even with hydrazine, which is the less hindered and the more powerful nucleophile used.

Polyazines and Polyazomethines with Didodecylthiophene Units for Selective Dispersion of Semiconducting Single‐Walled Carbon Nanotubes

“…Both polymers contain didodecylthiophene units interspersed with nitrogen atoms in their backbones, and the only difference is the presence of the benzene ring between the two nitrogen atoms in PAMDD, resulting in dissimilar polymer backbone planarity. [ 15 ] The extra aromatic ring makes PAMDD less planar and also gives it a higher band gap than PAZDD. Figure S1 (Supporting Information) displays the absorption and PL of the two polymers in solution.…”

“…The absorption of both systems ranges from 350 to 600 nm with the maxima at 475 nm for PAMDD, and at 513 nm for PAZDD, corresponding to the absorption of the lowest energy π-π* transition of the aromatic ring. [ 15 ] Figure 1 a reports the absorption spectra of the SWNT dispersions obtained with the two polymers using a nanotube to polymer weight ratio 1:2. The SWNT species (as indicated in the top fi gure) were assigned using the semiempirical formula [ 18 ] …”

“…We can qualitatively explain this behavior as being caused by the fact that PAZDD has a more fl exible backbone than PAMDD. [ 15 ] A more fl exible backbone allows a larger number of conformations, which makes the interaction with a larger number of different kinds of SWNT species possible. As previously mentioned, the phenyl rings in the PAMDD make the backbone stiffer, limiting the conformation of the polymer chain and favoring higher interaction with certain SWNTs, thanks to the increased π-π stacking.…”

“…[ 15 ] Poly(2,5-dimethylidynenitrilo-3,4-didodecylthienylene) (PAMDD) shows a very high extraction yield (up to 180 µg mL −1 ), which is similar to poly(3-dodecylthiophene-2,5-diyl) (P3DDT), while poly(3,4-didodecylthienylene)azine (PAZDD) has lower selectivity. The dissimilar wrapping efficiency of these two polymers for semiconducting SWNTs is attributed to the interplay between the affi nity for the nitrogen atoms of the highly polarizable walls of SWNTs and the mechanical fl exibility of the polymer backbones.…”

Synthesis and characterization of Schiff base complexes of Zr(IV) and Th(IV) complexes of Schiff base derived from furan 3- carboxaldehyde and 3- amino pyridine

“…The calculated grain size for Zr (IV) complex is in the range of 21-24 nm and for Th(IV) complex is in the range 20-19nm. This values suggested the crystals of the Zr(IV) and Th(IV) complexes are in nano size [18] . The results of antibacterial activity substantiate the findings of earlier researchers [19] , that biologically in active compounds become active and less biologically active compounds IJETST-Vol.||04||Issue||09||Pages 5861-5866||September||ISSN 2348-9480 2017 become more active upon coordination.…”