Vibrational characterization of poly(1‐methylpyrrole‐ co‐squaric acid) and poly(1‐dodecylpyrrole‐co‐squaric acid) by enhanced Raman spectroscopy

Abstract

Poly(1-methylpyrrole-co-squaric acid) (PMPS) and poly(1-dodecylpyrrole-co-squaric acid) (PDPS), copolymers of the class of polysquaraines, were synthesized and their structure determined by UV-VIS-NIR, resonance Raman and surface-enhanced Raman scattering (SERS) and electron paramagnetic resonance (EPR) spectroscopies. The spectroscopic results led to a structure different from that proposed in the literature, having radical units localized in the protonated squarate moieties and polypyrrole dication-like segments. The resonance Raman profiles indicate the presence of two chromospheres that are consistent with the electronic data. The Raman assignment was supported by density functional theory (DFT) calculations.

Pyrrolyl Squaraines–Fifty Golden Years

“…A final comment on the molecular structure of the polymers comes from the results of one particular study on the structure of two separate polysquaraines, one PMPS and the other made from 1-dodecylpyrrole [28]. The spectroscopic results of this study suggest that the incorporation of the known "one water molecule per squarate unit" (as mentioned previously) is actually part of the polysquaraine molecular structure 14.…”

“…Since then the (undoped) electrical conductivities of pyrrole-derived squaraines have been reported thirteen times [15,17,[20][21][22]28,43,47,49,56,58,59,61], with the best conduction being no greater than 5 × 10 −4 S/cm [21]. The reported band gap for this type III polysquaraine 9 was 0.79 eV, the lowest recorded for any pyrrole-derived polysquaraine.…”

“…This polymer, made from squaric acid and 1-methylpyrrole, was reported by Lynch et al to be an electrical insulator with a dielectric breakdown of 0.025-0.9 MV/cm [20], whereas Sant'Ana et al reported an electrical conductivity of ~10 −6 S/cm [28]. The difference between these two papers was the preparation of the polymer.…”

Co-doping with polysquaraine enhances the holographic optical data storage of PMMA/PQ photopolymers

“…The signals at 1610 and 1730 cm À1 represent the C-O and C¼O stretchings of the cyclobutenediylium-1,3-diolate moiety, respectively [11,15,16]. The strong C-H stretching of the C 8 H 17 units appeared as absorption bands at ca.…”

“…The strong C-H stretching of the C 8 H 17 units appeared as absorption bands at ca. 2800-3000 cm À1 [16]. The broad absorption band at 3300 cm À1 was produced as a result of intramolecular hydrogen bonding of the PSQ3 structures.…”