The synthesis and non-linear optical properties of (N-alkylpyrrol-2-yl)squaraine derivatives. Part 1

Lynch, Daniel Ε.; Geißler, Uwe; Peterson, I. R.; Floersheimer, M.; Terbrack, Roland; Liu, Feng; Fuchs, H. G.; Calos, Nicholas J.; Wood, Barry; Kennard, C. H. L.; Langley, G. John

doi:10.1039/a604111f

Cited by 29 publications

(37 citation statements)

References 20 publications

(15 reference statements)

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“…Ashwell et al in their re-preparation of 2,4-bis(N-octadecylpyrrol-2-yl)squaraine (which would currently be referred to as a 1,3-squaraine, not a 2,4-squaraine) gave the H positions in the 1 H NMR at (in reverse order) δ = 0.88, 1.25, 1.7-1.8, 3.86, 6.13, 6.65 and 7.42 ppm [13]. These positions (except for δ = 7.42 ppm) are identical to those reported for the starting material N-octadecylpyrrole (δ = 0.90, 1.25, 1.75, 3.86, 6.13 and 6.65 ppm) [11], indicating that Ashwell et al did little more than study the starting material, which is corroborated by their differential scanning calorimetry results showing a melting point of 32-36 °C. Thankfully, as far as the author (of this review) is aware, this mistake has not been made elsewhere by any other pyrrolyl squaraine researcher.…”

Section: Check Your 1 H Nmrsupporting

confidence: 67%

“…Other studies have been undertaken that just concentrate on the large two-photon absorption cross-sections that pyrrolyl squaraine dyes exhibit [32,33,52,55,66]. Following the discovery that symmetrical bis(anilino)squaraine dyes exhibit second-order nonlinear optical effects as Langmuir-Blodget deposited monolayers on hydrophilic glass slides [93], results for a range of pyrrolyl squaraines were similarly reported [11,13,14]. Latter second-order non-linear optical studies on pyrrolyl squaraines have employed electric-field induced second harmonic generation (EFISH) measurements, although these measurements can only be taken on unsymmetrical pyrrolyl squaraine dyes [39].…”

Section: Optical Propertiesmentioning

confidence: 85%

“…The simplest dye, 1,3-bis(1-alkylpyrrolyl)squaraine 1 (where R 2 , R 3 , R 4 = H), had λ max (CHCl 3 ) = 548.5 nm with λ max increasing with additional substitution around the pyrrole [14]. The early studies also found that the dyes were solvatochromic [3,6] (with the polymers also subsequently being found to be solvatochromic [10]) and that the dyes fluoresced (λ em > 580 nm) with varying efficiency in different solvents [6,7,11,14] and within a substituted methacrylate polymer [12] (with subsequent reports of the soluble polymers fluorescing [16]). Generally, pyrrolyl squaraine dyes are reported as being red-purple in colour whereas pyrrole-derived polysquaraines are dark blue-black, although in both cases surface plasmon optical effects can give the impression that the powders are metallic green, metallic yellow-brown or metallic red-purple [59].…”

Section: Optical Propertiesmentioning

confidence: 93%

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Pyrrolyl Squaraines–Fifty Golden Years

Lynch

2015

Metals

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Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such as the synthetic history, an understanding of the molecular structure, an overview of the optical properties, a discussion of both the electrical conduction properties, and magnetic properties, plus use of the particles of pyrrolyl squaraines, are presented. Furthermore, previously published results are not just presented; they are in certain cases collated and used to both highlight and explain important aspects of pyrrolyl squaraine chemistry.

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Section: Check Your 1 H Nmrsupporting

confidence: 67%

Section: Optical Propertiesmentioning

confidence: 85%

Section: Optical Propertiesmentioning

confidence: 93%

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Pyrrolyl Squaraines–Fifty Golden Years

Lynch

2015

Metals

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“…Brocks and Tol 13 calculated small band gap values for polysquaraines formed from squaric acid and molecules bearing groups such as phenyl, vinyl and amine. Later on Lynch et al 14 and Chenthamarakshan et al 15 prepared polysquaraines from squaric acid and substituted pyrroles, obtaining conducting polymers with small optical band gaps and high thermal stabilities. However, in all such previous investigations on polysquaraines, the focus was not on the detailed structural characterization of such materials.…”

Section: Introductionmentioning

confidence: 99%

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

Sant’Ana

Siqueira

Santos

et al. 2006

J Raman Spectroscopy

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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.

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confidence: 99%

Nonlinear Optical Properties of α-Arylpyrroles

et al. 2005

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Heteroaromatic compounds are promising for use in quantum electronic devices and as laser active media [1,2] and nonlinear generators of harmonics [3,4] with rather high nonlinearity coefficients. They are compatible with various types of substrates, namely, inorganic oxides and polymer compositions, and, therefore, can be readily integrated into optoelectronic devices. Among the numerous publications on this topic, only a few studies (for example, [3,5]) have indicated the possibility of obtaining high nonlinear-optical characteristics using compounds containing pyrrole rings.This study deals with the nonlinear-optical properties of a series of α -arylpyrroles ( I -XIV ) with various combinations of electron-donating and electron-withdrawing substituents in the benzene and pyrrole rings (table). Arylpyrroles became available due to development of a general method for the synthesis of pyrroles and N -vinylpyrroles from ketones and acetylene (via ketoximes) in superbasic media (the Trofimov reaction) [6,7]. The corresponding trifluoroacetyl derivatives and pyrrolecarboxylic acids were prepared by reported methods [8][9][10].The molecules of all compounds studied are noncentrosymmetric; therefore, they obey the condition of second-harmonic generation in the electric dipole approximation.Second-harmonic generation was carried out in powders by the method proposed by Kurtz and Perry [11]. The harmonic intensity was compared to that for a powder produced from a nonlinear LiIé 3 crystal with a high effective nonlinearity ( d eff = 4.1 × 10 -12 m/V) [12]. The second harmonic was excited by the radiation of a neodymium-yttrium-aluminum-garnet (Nd:YAG) laser with a modulated Q factor at the wavelength λ = 1064 nm. The exciting pulse intensity was ~10 7 W/cm 2 . The spectral composition and the amplitude of the second-harmonic pulse were monitored using a photomultiplier through an MDR-23 diffraction monochromator. For determining reabsorption of the harmonic, absorption spectra were recorded on a Specord UV/VIS spectrophotometer in the range 250-550 nm.According to the measurements, the second harmonic ( λ = 532 nm) was observed in a narrow spectral range (less than 1 nm) for pyrroles VI , XII , XIII , and XIV . The highest intensity (which was still five times lower than that for LiIO 3 ) was found for 2-(4-bromophenyl)-1-vinyl-5-trifluoroacetylpyrrole ( XIV ). The second harmonic of compound XIII was one order of magnitude weaker, and those for compounds VI and XII were at the CHEMISTRY Substituted pyrroles as potential second-harmonic generators Pyrrole R 1 R 2 R 3

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The synthesis and non-linear optical properties of (N-alkylpyrrol-2-yl)squaraine derivatives. Part 1

Cited by 29 publications

References 20 publications

Pyrrolyl Squaraines–Fifty Golden Years

Pyrrolyl Squaraines–Fifty Golden Years

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

Nonlinear Optical Properties of α-Arylpyrroles

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