Electrochromic Properties and Electrochemical Behavior of Marennine, a Bioactive Blue-Green Pigment Produced by the Marine Diatom Haslea ostrearia

Marennine has long been known as the unique peculiar pigment responsible for the natural greening of oysters. It is specifically produced by the marine diatom Haslea ostrearia and it is a natural blue molecule indeed promising for food industry because of the rarity of such non-toxic, blue-colored pigments. In the search for its still not defined molecular structure, investigation of the color changes with the redox state has been carried out combining different approaches. Reducing and oxidizing chemicals have been added to purified marennine solutions and a stable blue-green color has been confirmed for the oxidized state, while a yellow color corresponded to the reduced unstable state. Raman spectroscopy has been used to monitor changes in the Raman spectra corresponding to the different colored states, and cyclic voltammetry has allowed the detection of a redox system in which protons and electrons are exchanged. These findings show that marennine is a suitable stable blue pigment for use in food applications and help in the elucidation of the chromophore structure.

Quantum chemical studies, spectroscopic analysis and molecular structure investigation of 4-Chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoic acid

In this study, the FTIR, FT-Raman and UV-visible Spectra of furosemide molecule, C12H11ClN2O5S (with named, 4-chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoic acid), were recorded experimentally and theoretically. The optimized geometrical structure, harmonic vibration frequencies, and chemical shifts were computed using a hybrid-DFT (B3LYP) method and 6-31G(d,p) as the basis set. The complete assignments of fundamental vibrations were performed on the basis of the experimental results and Total Energy Distribution (TED) of the vibrational modes. The first order hyperpolarizability and relative properties of furosemide were calculated. The UV-Visible spectrum of the compound was recorded in the range 200–400 nm and the electronic properties, such as HOMO and LUMO energies, were determined by Time-Dependent DFT approach. Furthermore, Mulliken population analysis and thermodynamic properties were performed using B3LYP/6-31G(d,p) level for the furosemide compound.