A novel method of the synthesis of higher polymethinium salts

Makin, S. M.; Monich, N. V.; Shavrygina, O. A.; Berezhnaya, M. I.; Kheifets, S. A.

doi:10.1016/s0040-4020(01)83243-9

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…The Cy3·PF 6 , Cy5·PF 6 , and Cy7·PF 6 salts were prepared using standard precedures. − Cyanines similar to Cy9 + and Cy11 + , but without SMe substituents, have been mentioned occasionally in the literature . To the best of our knowledge, their synthesis has not been reported, although there are a few reports of the synthesis of other cyanines in this length regime. , The synthesis of Cy11·PF 6 was achieved from aldehyde 1 as shown in Figure b, by Vilsmeier formylation, reaction with aniline, and condensation with Fischer base 2 , , although the reaction gives a complex mixture of products and Cy11·PF 6 could only be isolated in 4% yield. A similar route gave Cy9·PF 6 in 42% yield.…”

Section: Resultsmentioning

confidence: 99%

A Peierls Transition in Long Polymethine Molecular Wires: Evolution of Molecular Geometry and Single-Molecule Conductance

Leary

Sangtarash

et al. 2021

J. Am. Chem. Soc.

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Molecules capable of mediating charge transport over several nanometers with minimal decay in conductance have fundamental and technological implications. Polymethine cyanine dyes are fascinating molecular wires because up to a critical length, they have no bond-length alternation (BLA) and their electronic structure resembles a one-dimensional free-electron gas. Beyond this threshold, they undergo a symmetry-breaking Peierls transition, which increases the HOMO−LUMO gap. We have investigated cationic cyanines with central polymethine chains of 5−13 carbon atoms (Cy3 + −Cy11 + ). The absorption spectra and crystal structures show that symmetry breaking is sensitive to the polarity of the medium and the size of the counterion. X-ray crystallography reveals that Cy9•PF 6 and Cy11•B(C 6 F 5 ) 4 are Peierls distorted, with high BLA at one end of the π-system, away from the partially delocalized positive charge. This pattern of BLA distribution resembles that of solitons in polyacetylene. The single-molecule conductance is essentially independent of molecular length for the polymethine salts of Cy3 + − Cy11 + with the large B(C 6 F 5 ) 4− counterion, but with the PF 6 − counterion, the conductance decreases for the longer molecules, Cy7 + −Cy11 + , because this smaller anion polarizes the π-system, inducing a symmetry-breaking transition. At higher bias (0.9 V), the conductance of the shorter chains, Cy3 + −Cy7 + , increases with length (negative attenuation factor, β = −1.6 nm −1 ), but the conductance still drops in Cy9 + and Cy11 + with the small polarizing PF 6 − counteranion.

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Section: Resultsmentioning

confidence: 99%

A Peierls Transition in Long Polymethine Molecular Wires: Evolution of Molecular Geometry and Single-Molecule Conductance

Leary

Sangtarash

et al. 2021

J. Am. Chem. Soc.

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“…41 1,2,3,3-Tetramethyl-3H-benzo[g]indolium iodide (0.42 g, 1.38 mmol) was dissolved in hot dry pyridine (2 mL) under a N 2 atmosphere. Upon cooling down to room temperature, (Z)-1,1,3,5,5-pentaethoxypent-2ene 78 (200 mg, 0.69 mmol) was added, and the mixture was stirred at room temperature for 3 h. Diethyl ether (50 mL) was added, and the resulting precipitate was filtered. The precipitate was suspended in CH 2 Cl 2 and filtered, and the solid matter was discarded.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Deciphering the Structure–Property Relations in Substituted Heptamethine Cyanines

et al. 2020

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Heptamethine cyanines (Cy7) are fluorophores essential for modern bioimaging techniques and chemistry. Here, we systematically evaluated the photochemical and photophysical properties of a library of Cy7 derivatives containing diverse substituents in different positions of the heptamethine chain. A single substitution allows modulation of their absorption maxima in the range of 693–805 nm and photophysical properties, such as quantum yields of singlet-oxygen formation, decomposition, and fluorescence or affinity to singlet oxygen, within 2–3 orders of magnitude. The same substituent in different positions of the chain often exhibits distinctly contradictory effects, demonstrating that both the type and position of the substituent are pivotal for the design of Cy7-based applications. The combination of experimental results with quantum-chemical calculations provides insights into the structure–property relationship, the elucidation of which will accelerate the development of cyanines with properties tailored for specific applications, such as fluorescent probes and sensors, photouncaging, photodynamic therapy, or singlet-oxygen detection.

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“…In 2021, Xu, et al, 43 reported access to a C7 spacer (2 in Scheme 1), which importantly expanded earlier work on similar compounds by demonstrating the synthetic conditions to access it. [44][45][46] That molecule was used in this study to produce the rst heptamethine indolizinecyanine in literature (SO3C7, Scheme 1). We hypothesized this extended p-bridge dye would allow for the detection of albumin in latent blood stains through NIR light use even when albumin is covered by black materials.…”

Section: Synthetic Designmentioning

confidence: 99%

Switch-on near infrared emission in albumin behind dark fabric: toward application in forensic latent bloodstain detection

Saucier,

Kruse,

Lewis

et al. 2024

RSC Adv.

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A novel method of the synthesis of higher polymethinium salts

Cited by 6 publications

References 6 publications

A Peierls Transition in Long Polymethine Molecular Wires: Evolution of Molecular Geometry and Single-Molecule Conductance

A Peierls Transition in Long Polymethine Molecular Wires: Evolution of Molecular Geometry and Single-Molecule Conductance

Deciphering the Structure–Property Relations in Substituted Heptamethine Cyanines

Switch-on near infrared emission in albumin behind dark fabric: toward application in forensic latent bloodstain detection

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