The Effect of Pressure upon Optical Absorption

Wick, Frances G.

doi:10.2307/20026031

Cited by 6 publications

(3 citation statements)

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“…The spectral width of a UV-vis absorption band, in particular, the S 0 → S 1 absorption band, is indicative of the structural rigidity. For this reason, a reduced bandwidth is observed when vibration freedoms are restricted by lower temperature or increased pressure . To calculate the fwhm, it is necessary to deconvolute the spectra-of-interest (in unit of cm –1 ) to its constituting Gaussian-shape absorption bands.…”

Section: Resultsmentioning

confidence: 76%

Stable, Bright, and Long-Fluorescence-Lifetime Dyes for Deep-Near-Infrared Bioimaging

Dong

Wei

et al. 2022

J. Am. Chem. Soc.

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Near-infrared (NIR) fluorophores absorbing maximally in the region beyond 800 nm, i.e., deep-NIR spectral region, are actively sought for biomedical applications. Ideal dyes are bright, nontoxic, photostable, biocompatible, and easily derivatized to introduce functionalities (e.g., for bioconjugation or aqueous solubility). The rational design of such fluorophores remains a major challenge. Silicon-substituted rhodamines have been successful for bioimaging applications in the red spectral region. The longer-wavelength silicon-substituted congeners for the deep-NIR spectral region are unknown to date. We successfully prepared four silicon-substituted bis-benzannulated rhodamine dyes (ESi5a–ESi5d), with an efficient five-step cascade on a gram-scale. Because of the extensive overlapping of their HOMO–LUMO orbitals, ESi5a–ESi5d are highly absorbing (λabs ≈ 865 nm and ε > 105 cm–1 M–1). By restraining both the rotational freedom via annulation and the vibrational freedom via silicon-imparted strain, the fluorochromic scaffold of ESi5 is highly rigid, resulting in an unusually long fluorescence lifetime (τ > 700 ps in CH2Cl2) and a high fluorescence quantum yield (ϕ = 0.14 in CH2Cl2). Their half-lives toward photobleaching are 2 orders of magnitude longer than the current standard (ICG in serum). They are stable in the presence of biorelevant concentration of nucleophiles or reactive oxygen species. They are minimally toxic and readily metabolized. Upon tail vein injection of ESi5a (as an example), the vasculature of a nude mouse was imaged with a high signal-to-background ratio. ESi5 dyes have broad potentials for bioimaging in the deep-NIR spectral region.

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Section: Resultsmentioning

confidence: 76%

Stable, Bright, and Long-Fluorescence-Lifetime Dyes for Deep-Near-Infrared Bioimaging

Dong

Wei

et al. 2022

J. Am. Chem. Soc.

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“…For a Co(II) octahedral complex, the three t 2g orbitals contain five electrons and the two e g orbitals contain one electron each. The bands observed in our spectra are from the spin-allowed transitions 4 A 2 [et 2 3 ] → 4 T 1 (P) and 4 T 1g (F) [t 2g e g 2 ] → 4 T 1g (P) for the tetrahedral and octahedral complexes, respectively.…”

Section: Introductionmentioning

confidence: 74%

“…To our knowledge, the first reported work on static high-pressure effects on CoCl 2 solution spectra is that of Wick . She did static high-pressure experiments (up to 0.15 GPa) on CoCl 2 /H 2 O solutions.…”

Section: Introductionmentioning

confidence: 99%

Pressure Driven Ligand Rearrangement Reaction in a Cobalt−Chloride Complex

1997

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We report experimental results concerning the occurrence and rate of the reaction CoCl 2 (EtOH) 2 + 4EtOH f Co(EtOH) 6 2+ + 2Cl -induced by transient high pressure. The experimental probe used to interrogate the system was time-resolved visible light spectroscopy. The transient high pressures induced in the samples were produced by projectiles launched by a single-stage gas gun; consequently, the hydrodynamic flows experienced by the samples were well-defined. The pressures the test samples were subjected to were in the range 0.75-6.7 GPa. Ambient-pressure control experiments, in which the reaction was induced by altering sample temperature, are also reported. For a 20/80 wt % CoCl 2 ‚6H 2 O/EtOH solution, shocked to ca. 6.7 GPa, we observed the disappearance of signature spectrum of the CoCl 2 (EtOH) 2 species and the appearance of the spectrum of the Co(EtOH) 6 2+ structure. The cobalt structure on the left side of the equilibrium equation above is tetrahedral, while that on the right is octahedral. In shock-pressurized systems, we have observed the disappearance of the tetrahedral complex and found the time scale for this process is ca. 200 ns. Similarly, in other shock experiments, we have observed the appearance of the octahedral complex and found the time scale for this process is ca. 500 ns. The relevance of the present results to ideas concerning the character of ionic chemical reactions possibly important in detonating condensed-phase explosives is briefly discussed.

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Effect of pressure on the helix and random coil forms of poly(D‐glutamic acid)

Suzuki¹,

Taniguchi²

1968

Biopolymers

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SynopsisThe absorption spectrum of the aqueous solution of acridine orange (A0)-poly-(D-glutamic acid) (PDGA) complex a t pH 4.5 (helix form) did not show any wavelength shift, but at pH 7.5 (coil form) changed to the absorption curve of the helix form by compression up to 4500 atm. The ionization degree of PDGA estimated from the electric conductivity of the aqueous solution of PDGA a t 4500 atm. was a value of about 5.3%. The entropy of the helix formation of PDGA from the titration data at 1 atm. and 30°C. was negative -2.98 e.u. I t will be concluded in this report that the volume change for coil to helix could be positive for PDGA and negative for AO-PDGA complexes.

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The Effect of Pressure upon Optical Absorption

Cited by 6 publications

References 0 publications

Stable, Bright, and Long-Fluorescence-Lifetime Dyes for Deep-Near-Infrared Bioimaging

Stable, Bright, and Long-Fluorescence-Lifetime Dyes for Deep-Near-Infrared Bioimaging

Pressure Driven Ligand Rearrangement Reaction in a Cobalt−Chloride Complex

Effect of pressure on the helix and random coil forms of poly(D‐glutamic acid)

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