Theoretical study of the photoisomerization of 1,2-bispyrazinyl-ethylene and the halogen ion salts of 1-Pyrazinyl-2-(4'-methylpyrazinyl)ethylene.

Context: It has been reported that photoexcitation of azastilbene compounds like E-1,2-bispyrazinyl-ethylene (bpe) can undergo E → Z photoisomerization of its quaternary salts via the excited triplet state. However, experimentally it is possible to get low fluorescence and photoisomerisation quantum yields in a state with higher internal conversion than intersystem crossing. We modelled bpe and its methylated derivative (bpeMe), as well as its quaternary halogen salts (bpeMeX with X = F, Cl, Br and I) to study levels of fluorescence, phosphorescence and excited state potential energy surfaces (PES).

Source apportionment of fine atmospheric particles in Bloemfontein, South Africa, using positive matrix factorization.

Air pollution is of major health and environmental concern globally and in South Africa. Studies on the sources of PM air pollution in low- and middle-income countries such as South Africa are limited. This study aimed to identify local and distant sources of PM pollution in Bloemfontein.

Nanocomposites with ZrO@S-Doped g-CN as an Enhanced Binder-Free Sensor: Synthesis and Characterization.

This study describes new electrocatalyst materials that can detect and reduce environmental pollutants. The synthesis and characterization of semiconductor nanocomposites (NCs) made from active ZrO@S-doped g-CN is presented. Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) measurements were used to examine electron transfer characteristics of the synthesized samples.

Synthesis and characterization of CuO@S-doped g-CN based nanocomposites for binder-free sensor applications.

This study presents the simultaneous exfoliation and modification of heterostructured copper oxide incorporated sulfur doped graphitic carbon nitride (CuO@S-doped g-CN) nanocomposites (NCs) synthesized chemical precipitation and pyrolysis techniques. The results revealed that the approach is feasible and highly efficient in producing 2-dimensional CuO@S-doped g-CN NCs. The findings also showed a promising technique for enhancing the optical and electrical properties of bulk g-CN by combining CuO nanoparticles (NPs) with S-doped g-CN.

Polypyridine Os complexes electrochemical data.

The data presented in this article are relevant to the research article, "Electrochemistry of Os bipyridyl and phenanthroline complexes, comparison with Ru and Fe" (van der Westhuizen, 2020). Cyclic voltammograms illustrating Os oxidations of eight osmium(II) complexes are presented in this article. The data were obtained under similar experimental conditions, at scan rates with magnitudes ranging from 0.

Cyclic voltammograms and electrochemical data of Fe polypyridine complexes.

Data in this article is associated with our research article, Electronic Properties of Fe Charge Transfer Complexes - a Combined Experimental and Theoretical Approach [1]. The oxidation and reduction potentials of fourteen Fe complexes are presented here, as extracted from the redox data obtained from its associated cyclic voltammograms, which were measured at scan rates varying from 0.05 V.

Electrochemical data of polypyridine complexes of Ru(II).

The data here-in presented is associated to the research article, Electrochemistry and spectroscopy of substituted [Ru(phen)] and [Ru(bpy)3] complexes [1]. Redox data obtained from cyclic voltammetry experiments of the oxidation of Ru(II) to Ru(III) of thirteen Ru(II)-polypyridine complexes is presented in this data in brief article. Data is obtained from the cyclic voltammograms at scan rates of two orders of magnitude (0.

Seven Chromisms Associated with Dithizone.

Variations in the electromagnetic wavelengths of absorption and reflection of molecules do not only make life colorful but also are often of central importance in solar energy conversion and optoelectronic information processing and transfer. Dithizone and its derivatives and complexes are, to our knowledge, probably the most "colorful" compound, being responsive to no less than seven different external stimuli that effect color change. Apart from a more detailed discussion of the cyclic voltammetry and observed electrochromism in the SCH-substituted free ligand and mercury complex, concentratochromism, solvatochromism, halochromism, thermochromism, and chronochromism in the ligand, and photochromism in the carboxy-functionalized phenylmercury(II) complex are also presented here.

Synthesis and kinetics of sterically altered photochromic dithizonatomercury complexes.

Following a previous study where 12 electronically altered dithizones were synthesized, here we report on attempts to synthesize 26 dithizones. The purpose was to explore the boundaries within which dithizones may be synthesized, explore spectral tuning possibilities, and investigate steric effects on the photochromic reaction of its mercury complexes. Contrary to expectation, large substituents like phenoxy groups increased the rate of the photochromic back-reaction.

Femtosecond laser spectroscopy and DFT studies of photochromic dithizonatomercury complexes.

The ultrafast dynamics of the photochromic reaction of dithizonatophenylmercury(II) was recently reported. For purpose of investigating the effect of electronically different substituents (X = o-F, m-F, p-F, p-Cl, o-CH3, m-CH3, p-CH3, m,p-diCH3, p-OCH3, o-SCH3, and p-SCH3) on this reaction, a series of phenyl-substituted dithizones were synthesized and complexed with phenylmercury(II). A variation of more than 3 ps in ground state repopulation times was observed, with the o-methyl derivative absorbing both at shortest wavelength and having the fastest repopulation time, while the p-S-methyl derivative lies at the opposite extremity.

(1,5-Diphenyl-thio-carbazonato-κS)trimethyl-tin(IV).

In the title compound, [Sn(C13H11N4S)(CH3)3], the Sn(IV) atom is coordinated by an S atom from the 1,5-diphenyl-thio-carbazonato (L) ligand [Sn-S 2.4710 (6) Å] and by three methyl groups [Sn-C 2.123 (3)-2.

1-(2-Meth-oxy-phen-yl)-2-{[2-(2-meth-oxy-phen-yl)hydrazinyl-idene](nitro)-meth-yl}diazene.

In the title compound, C(15)H(15)N(5)O(4), a nitro-formazan derivative, the formazan unit is essentially planar with an r.m.s.

1,5-Bis(2-methyl-phen-yl)-3-nitro-formazan.

In the title compound, C(15)H(15)N(5)O(2), the nitro O atoms are disordered over two sets of sites with an occupancy ratio of 0.75 (4):0.25 (4).

(E)-1-[2-(Methyl-sulfan-yl)phen-yl]-2-({(E)-2-[2-(methyl-sulfan-yl)phen-yl]hydrazinyl-idene}(nitro)-meth-yl)diazene.

In the title compound, C(15)H(15)N(5)O(2)S(2), the phenyl rings make dihedral angles of 4.03 (4) and 9.77 (5)° with the plane defined by the central N-N-C-N-N atoms (r.

[1,5-Bis(4-fluoro-phen-yl)thio-carbazo-nato-κN,S]phenyl-mercury(II) dichloro-methane hemisolvate.

In the title compound, [Hg(C(6)H(5))(C(13)H(9)F(2)N(4)S)]·0.5CH(2)Cl(2), the Hg(C(6)H(5)) units are twisted out of the planes of the thio-carbazo-nate ligands by 61.49 (10) and 67.

Dithizone and its oxidation products: a DFT, spectroscopic, and X-ray structural study.

Air oxidation of ortho-fluorodithizone resulted in the first X-ray resolved structure of a disulfide of dithizone, validating the last outstanding X-ray structure in the oxidation of dithizone, H(2)Dz, which proceeds via the disulfide, (HDz)(2), to the deprotonated dehydrodithizone tetrazolium salt, Dz. Density functional theory calculations established the energetically favored tautomers along the entire pathway; in gas phase and in polar as well as nonpolar solvent environments. DFT calculations using the classic pure OLYP and PW91, or the newer B3LYP hybrid functional, as well as MP2 calculations, yielded the lowest energy structures in agreement with corresponding experimental X-ray crystallographic results.

Ultrafast photochemistry of dithizonatophenylmercury(II).

The initial photochromic reaction of dithizonatophenylmercury(II) in solution was investigated by femtosecond transient absorption spectroscopy. Ultrafast excitation within less than 100 fs caused a radiationless photoreaction with a time constant of 1.5 ps, which is interpreted as C=N isomerization through a conical intersection.

Low-temperature redetermination of 1,3-bis-(penta-fluoro-phen-yl)triazene.

The crystal structure of the title compound, (C(6)F(5))(2)N(3)H, is stabilized by N-H⋯N hydrogen bonding, forming centrosymmetric dimers organized in a herringbone motif. Important geometrical parameters are N-N = 1.272 (2) and 1.

2,3-Bis(3-fluoro-phen-yl)tetra-zolium-5-thiol-ate.

The zwitterionic title compound, C(13)H(8)F(2)N(4)S, is situated on a twofold rotation axis running along the C-S [1.691 (2) Å] single bond. The phenyl-ene ring is twisted out of the tetra-zolium plane by 42.

A DFT perspective on the structures and electronic spectra of the orange and blue isomers of photochromic dithizonatophenylmercury(II).

The molecular structure and electronic spectra of the orange and blue isomers of the photochromic compound dithizonatophenylmercury(II) were theoretically studied utilizing density functional (DFT) methods. Computed structural results are in agreement with previously reported X-ray crystal data of the orange resting state. The herewith newly proposed geometrical structure of the blue photoexcited state is favored by more than 35 kJ x mol-1 relative to the historically hypothesized geometry of the blue isomeric form.

2,3-Bis(2-methoxy-phen-yl)tetra-zolium-5-thiol-ate-acetone-dichloro-methane (1/0.4/0.1).

In the title compound, C(15)H(14)N(4)O(2)S·0.4C(3)H(6)O·0.1CH(2)Cl(2), two benzene rings in the ortho-meth-oxy dehydro-dithizone (omd) mol-ecule are twisted out of the tetra-zole plane with the meth-oxy groups in a cis orientation relative to the tetrazole backbone.