Squaraine chemistry. On the anomalous mass spectra of bis(4-dimethylaminophenyl)squaraine and its derivatives

Law, Kock‐Yee; Bailey, F. C.; Bluett, Lynn J.

doi:10.1139/v86-267

Cited by 47 publications

(33 citation statements)

References 2 publications

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“…Regardless of the precursors in these syntheses, the final squaraine formation step involves the condensation of 4 and an N, N-dialkylaniline (9). It becomes obvious that if one can develop an independent synthesis of 4, one would not only be able to op 'mize the reaction condition for the squaraine formation st 1 p, but also have access to unsymmetrical squaraines when an appropriate aniline reactant is chosen.…”

Section: Resultsmentioning

confidence: 99%

“…The condition for the condensation reaction is investigated using 4 and N,Ndimethylaniline as reactants. The squaraine product is l a ; the quality of the product obtained can be compared with other l a samples (9). Results showed that, when 4 and N,N-dimethylaniline were condensed in refluxing 1-butanol (2), 1-heptanol (under reduced pressure) (4), or 2-propanol (in the presence of tributyl orthoformate) (1 1, 12), a greenish- solid was obtained.…”

Section: Ch30mentioning

confidence: 99%

“…The traditional synthesis, which involves the condensation of one equivalent of squaric acid, and two equivalents of an N , Ndimethylaniline derivative in an azeotropic solvent, is very straightforward and versatile (2); a large number of squaraine derivatives have been synthesized by this procedure (2)(3)(4)(5)(6)(7)(8).…”

Section: Introductionmentioning

confidence: 99%

“…developed to circumvent the performance problem (9,10). cycloaddition -condensation reaction sequence, has been The common starting material for these procedures is squaric developed (1 1 , 12).…”

Section: Introductionmentioning

confidence: 99%

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Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Law¹,

Bailey²

1993

Can. J. Chem.

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A new approach to l-(p-dimethylaminophenyl)-2-hydroxycyclobutene-3,4-dione (4), a precursor for the synthesis of symmetrical and unsymmetrical photoconductive squaraines, is described. In situ generation of p-nitrophenyl ketene, by the reaction of p-nitrophenylacetyl chloride and triethylamine in the presence of tetraethoxyethylene in anhydrous ether, results in a (2+2) cycloaddition between the ketene and the electron-rich olefin. The cycloadduct generated, 6, was hydrolyzed to give 1-(p-nitropheny1)-2-hydroxycyclobutene-3,4-dione (5) in 51% yield. Reductive alkylation of 5 by hydrogen in the presence of formaldehyde in DMF at 50-60°C affords 4 in 81 % yield. The overall yield of 4 is 41 % from tetraethoxyethylene and is significantly better than other preparative procedures of 4 based on a partial Friedel-Crafts reaction or an arylation reaction of a squaric acid derivative with an aniline, where yields ranging from 8.5% to 24% were reported. Condensations of 4 with 2 equivalents of N, N-dimethylaniline and its derivatives in refluxing 2-propan01 in the presence of 6 equivalents of tributyl orthoformate yield symmetrical squaraine l a and unsymmetrical squaraines lb-le. The synthesis is accomplished by a (2+2) cycloaddition -reductive alkylation -condensation reaction sequence and represents a new, cost-effective synthesis for photoconductive squaraines where the expensive squaric acid reactant is bypassed. The spectroscopic and the solid state properties of la-le have been studied. Results show that the properties exhibited by l a -l e are essentially identical to those exhibited by other photoconductive, symmetrical squaraines that are synthesized by other known processes. From the resemblance in solid state properties, la-le are expected to be photoconductive. This has indeed been observed in preliminary experiments.KOCK-YEE LAW et F. COURT BAILEY. Can. J. Chem. 71,494 (1993) On dCcrit une nouvelle approche pour la preparation de la l-(p-dimethylaminophCnyl)-2-hydroxycyclobut~ne-3,4-dione (4), un precurseur dans la synthese de squarai'nes photoconductrices symetriques et non-symetriques. La generation in situ du p-nitrophknyl cetene, par la reaction du chlorure de p-nitrophCnylacetyle avec la triethylamine en presence de tCtraCthoxy6thylene dans l'ether anhydre, conduit 2 une cycloaddition (2+2) du c$t&ne et de l'olefine riche en electrons. L'hydrolyse du cycloadduit, 6, ainsi gCnerC conduit 2 la 1-(p-nitrophCny1)-2-hydroxycyclobut&ne-3-done (5) avec un rendement de 51%. L'alkylation reductrice de 5 par de l'hydrogene en presence de formaldehyde dans de DMF, a 50-60°C, fournit le composC 4 avec un rendement de 8 1 %. Le rendement global de 4 est de 41% B p a i r du tCtrakthoxy6thylene et ce rendement est supkrieur a ceux obtenus lors de preparations impliquant une reaction de Friedel-Crafts partielle ou une reaction d'arylation d'un derive de l'acide squarique avec de l'aniline alors que les rendements rapportks sont de l'ordre de 8,5 a 24%. Les condensations de 4 avec deux equivalents de N,N-dimethylanil...

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Section: Resultsmentioning

confidence: 99%

Section: Ch30mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Law¹,

Bailey²

1993

Can. J. Chem.

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“…A number of squaraines were prepared from di-12-butyl squarate using these optimized conditions, and the yields are tabulated in Table 4.12 The yields of the same set of squaraines synthesized by the traditional acid route are also given for comparison (15). Comparison indicates that very similar chemical yields are obtained from both procedures.…”

Section: Scope Of the Ester Route Sjntlzesismentioning

confidence: 99%

Squaraine chemistry. Synthesis of bis(4-dimethylaminophenyl)squaraine from dialkyl squarates. Mechanism and scope of the synthesis

Law¹,

Bailey²

1986

Can. J. Chem.

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The mechanism and the scope of the synthesis of bis(4-dialky1aminoaryl)squaraines from di-n-butyl squarate and N,N-dialkylanilines have been studied. Results show that water and acid are key factors of the synthesis, and these two factors have been optimized. Yields of squaraine are also found to be sensitive to the steric effect provided by the alkyl chain in dialkyl squarates as well as to the concentration of the aniline reagent used in the synthesis. Mechanistic results suggest that alkyl squarate is the precursor of the synthesis, and that squaraine is formed by diarylation of alkyl squarate with an N,N-dialkylaniline derivative. Under optimized conditions, a number of squaraines have been synthesized. Yields, which are comparable to those synthesized from squaric acid. are obtained. Product analysis with good material balance has been achieved, and results show that arylation and diarylation of the starting di-n-butyl squarate are major side reactions in the squaraine synthesis.KOCK-YEE LAW et F. COURT BAILEY. Can. J . Chem. 64, 2267 (1986) On a 6tudiC le mecanisme et la gCnCralite de la synthese des bis(dia1kylamino-4 aryl) squarai'nes i partir du squarate de di-n-butyle et des N.N-dialkylanilines. Les rksultats indiquent que l'eau et l'acide sont des facteurs dkterminants dans la synthese et on a optimise ces deux facteurs. On a aussi trouve que les rendements en squaraine sont sensibles aux effets stkriques des chaines alkyles des squarates dialkylCs ainsi qu'i la concentration de l'aniline utiliske dans la synthese. Les rksultats mecanistiques suggerent que le squarate d'alkyle est un prkcurseur dans la synthese et que la squarai'ne se forme par une diarylation du squarate d'alkyle par un dkrivk N.N-dialkylaniline. Utilisant des conditions optimiskes. on a synthCtisC un certain nombre de squaraines. On a obtenu des rendements qui sont comparables a ceux obtenus lors de la synthese a partir de l'acide squarique. En se basant sur les produits dCtectCs, on a obtenu une bonne balance des rCactifs, et les resultats dkmontrent que l'arylation et la diarylation du squarate de di-n-butyle de depart sont des reactions secondaires importantes dans la synthbse de la squarai'ne .

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Facile One‐Step Growth and Patterning of Aligned Squaraine Nanowires via Evaporation‐Induced Self‐Assembly

et al. 2008

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Organic 1D nanomaterials based on low-molecular-weight semiconducting organic compounds are of interest because they possess unique properties for use in electronic, optoelectronic, and photonic nanodevices.[1] Different organic materials and methods have been employed to synthesize 1D single-crystal nanostructures. [2] While there are reports on fabricating organic 1D single crystals on specific device platforms, [3] relatively few of these reports deal with aligned organic 1D nanostructures [4] because they are complex to pattern; [5] often requiring templates, an external electric field, or surface-invasive steps. Consequently, simple patterning and aligning methods of 1D crystals are highly desirable in the pursuit of low-cost, large-scale fabrication of parallel device arrays. Here, we report a one-step method that can enable the growth, alignment, and periodic patterning of organic 1D single-crystal nanowires on a solid substrate. This method combines the processes of solvent-evaporation-induced selfassembly, contact line pinning, and dewetting, thus promising to be a simple and versatile approach to prepare sophisticated nanostructures. [6,7] To demonstrate the efficiency of the method we choose a squaraine dye, 2,4-bis[4-(N,N-dimethylamino)phenyl]squaraine (SQ), as model organic semiconductor, because squaraines are a novel class of organic dyes for photonic applications such as imaging, nonlinear optics, photovoltaics, biological labeling, and photodynamic therapy.[8] Both ground and excited states of SQ are intramolecular donor-acceptor-donor charge-transfer (D-A-D CT) states and have been studied theoretically.[9] SQ molecules easily form aggregates in a ''slipped stack'' arrangement because of strong intermolecular interactions between the acceptor (A) and the donor (D) groups (Fig. S1 in the Supporting Information). [10] As it has been shown that strong donor-acceptor dipole-dipole intermolecular interactions can direct the growth of 1D nanostructures, [11] we expect SQ also to have a strong tendency to form 1D nanostructures under appropriate conditions. We report here the preparation of SQ nanostructures by solvent evaporation on a horizontal substrate. In a typical experiment, a drop of SQ/CH 2 Cl 2 solution (0.02 mM, about 10 mL) was placed on a silicon substrate at 20 8C. After complete evaporation of solvent, the substrate was examined by scanning electron microscopy (SEM). As shown in Figure 1a, many nanowires were deposited on the substrate. The majority of the nanowires had a length of about 40 mm and a diameter of 100-300 nm. The dimensions of the nanowires were found to be sensitive to the surface morphology of the substrate, temperature, and evaporation rate. However, under a saturated vapor environment, no nanowires formed on the substrate after solvent evaporation.The morphology of the nanowires was further characterized by transmission electron microscopy (TEM; Fig. 1b), which shows that the SQ nanostructures are solid wires of nanometer diameter. The nanowires are single-crystall...

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Squaraine chemistry. On the anomalous mass spectra of bis(4-dimethylaminophenyl)squaraine and its derivatives

Cited by 47 publications

References 2 publications

Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Squaraine chemistry. Synthesis of bis(4-dimethylaminophenyl)squaraine from dialkyl squarates. Mechanism and scope of the synthesis

Facile One‐Step Growth and Patterning of Aligned Squaraine Nanowires via Evaporation‐Induced Self‐Assembly

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