Structure, stability and spectral properties of seleno[n]helicenes (n = 1–10)

2020 ◽  
Vol 44 (2) ◽  
pp. 428-441
Author(s):  
Rahul Kumar ◽  
Dilip Kumar Maity
Keyword(s):  
Excited State ◽  
Spectral Properties ◽  
Radical Cations ◽  
Strong Absorption ◽  
Structure Stability ◽  
Absorption Bands ◽  
Stable Structures

The most stable structures of seleno[n]helicenes (n = 3–10) are flexible and helical in nature. The excited state results show that many of the seleno[n]helicene radical cations have strong absorption bands in the IR region.

scholarly journals Microhydration of ionized building blocks of DNA/RNA: infrared spectra of pyrimidine$$^{+}$$-$$(\hbox {H}_{2}\hbox {O})_{\text {1-3}}$$ clusters

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Kuntal Chatterjee ◽  
Otto Dopfer
Keyword(s):  
Density Functional ◽  
Size Range ◽  
Density Functional Theory Calculations ◽  
Building Blocks ◽  
Ion Solvation ◽  
Structure Stability ◽  
Consistent Picture ◽  
Three Body ◽  
And Function ◽  
Stable Structures

Abstract Hydration of biomolecules is an important physiological process that governs their structure, stability, and function. Herein, we probe the microhydration structure of cationic pyrimidine (Pym), a common building block of DNA/RNA bases, by infrared photodissociation spectroscopy (IRPD) of mass-selected microhydrated clusters, $$\hbox {Pym}^{+}$$ Pym + -$$\hbox {W}_{n}$$ W n (W=$$\hbox {H}_{2}\hbox {O}$$ H 2 O ), in the size range $$n=1$$ n = 1 –3. The IRPD spectra recorded in the OH and CH stretch range are sensitive to the evolution of the hydration network. Analysis with density functional theory calculations at the dispersion-corrected B3LYP-D3/aug-cc-pVTZ level provides a consistent picture of the most stable structures and their energetic and vibrational properties. The global minima of $$\hbox {Pym}^{+}$$ Pym + -$$\hbox {W}_{n}$$ W n predicted by the calculations are characterized by H-bonded structures, in which the H-bonded $$\hbox {W}_{n}$$ W n solvent cluster is attached to the most acidic C4–H proton of $$\hbox {Pym}^{+}$$ Pym + via a single CH...O ionic H-bond. These isomers are identified as predominant carrier of the IRPD spectra, although less stable local minima provide minor contributions. In general, the formation of the H-bonded solvent network (exterior ion solvation) is energetically preferred to less stable structures with interior ion solvation because of cooperative nonadditive three-body polarization effects. Progressive hydration activates the C4–H bond, along with increasing charge transfer from $$\hbox {Pym}^{+}$$ Pym + to $$\hbox {W}_{n}$$ W n , although no proton transfer is observed in the size range $$n\leqslant $$ n ⩽ 3. The solvation with protic, dipolar, and hydrophilic W ligands is qualitative different from solvation with aprotic, quadrupolar, and hydrophobic $$\hbox {N}_{2}$$ N 2 ligands, which strongly prefer interior ion solvation by $$\uppi $$ π stacking interactions. Comparison of $$\hbox {Pym}^{+}$$ Pym + -W with Pym-W and $$\hbox {H}^{+}$$ H + Pym-W reveals the drastic effect of ionization and protonation on the Pym...W interaction. Graphic Abstract

Aryl Sulfoxide Radical Cations. Generation, Spectral Properties, and Theoretical Calculations

2006 ◽  
Vol 110 (32) ◽  
pp. 9940-9948 ◽  
Author(s):  
Enrico Baciocchi ◽  
Tiziana Del Giacco ◽  
Maria Francesca Gerini ◽  
Osvaldo Lanzalunga
Keyword(s):  
Spectral Properties ◽  
Theoretical Calculations ◽  
Radical Cations

scholarly journals Detection limits of organic compounds achievable with intense, short-pulse lasers

The Analyst ◽  
2015 ◽  
Vol 140 (12) ◽  
pp. 4270-4276 ◽  
Author(s):  
Jordan Miles ◽  
Simone De Camillis ◽  
Grace Alexander ◽  
Kathryn Hamilton ◽  
Thomas J. Kelly ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Organic Molecules ◽  
Short Pulse ◽  
Detection Limits ◽  
Strong Absorption ◽  
Absorption Bands ◽  
Short Pulse Lasers

Many organic molecules have strong absorption bands which can be accessed by ultraviolet short pulse lasers to produce efficient ionization.

Fourier-transform photoacoustic spectroscopy: a more complete method for quantitative analysis

1986 ◽  
Vol 64 (9) ◽  
pp. 1081-1085 ◽  
Author(s):  
M. Choquet ◽  
G. Rousset ◽  
L. Bertrand
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
Quantitative Analysis ◽  
Photoacoustic Spectroscopy ◽  
Photoacoustic Signal ◽  
Strong Absorption ◽  
Absorption Bands ◽  
Asbestos Fibers ◽  
Fourier Transform Spectra ◽  
Signal Saturation

Strong absorption bands of photoacoustic Fourier-transform spectra are often truncated relative to weaker bands owing to signal saturation. To correct this problem, we propose processing both the phase and the amplitude information in the photoacoustic signal. Under certain conditions, easily fulfilled in typical experiments, we are able to calculate the absolute absorption spectrum from the photoacoustic data. Experimental results are given for asbestos fibers (chrysotile).

The influence of substituents on spectral properties of radical-cations and dications derived from certain phenothiazines

1975 ◽  
Vol 12 (2) ◽  
pp. 397-399 ◽  
Author(s):  
Edward R. Biehl ◽  
Huh-Sun Chiou ◽  
Scott Kennard ◽  
Joe Keepers ◽  
P. C. Reeves
Keyword(s):  
Spectral Properties ◽  
Radical Cations ◽  
Influence Of Substituents

scholarly journals Hydroporphyrins of the meso-tetra(hydroxyphenyl)porphyrin series as tumour photosensitizers

1989 ◽  
Vol 261 (1) ◽  
pp. 277-280 ◽  
Author(s):  
R Bonnett ◽  
R D White ◽  
U J Winfield ◽  
M C Berenbaum
Keyword(s):  
Visible Spectrum ◽  
Strong Absorption ◽  
Absorption Bands

Four new hydroporphyrins [the o, m and p isomers of 5,10,15,20-tetra(hydroxyphenyl)chlorin and 5,10,15,20-tetra(m-hydroxyphenyl)bacteriochlorin] related to the tetra(hydroxyphenyl)porphyrins have been prepared. They show the expected strong absorption bands in the red region of the visible spectrum and are found to be very effective tumour photosensitizers.

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