SCREENING CONSTANT BY UNIT NUCLEAR CHARGE CALCULATIONS OF THE RYDBERG SERIES FROM METASTABLE STATE OF CALCIUM ION

We report in this paper energy positions of Rydberg series from metastable state of Ca3+ ion.. Calculations are performed up to n = 20 using the Screening Constant by Unit Nuclear Charge (SCUNC). The present results compared wellwith the experimental data of Ghassan A Alna’washi which are the only available values.The accurate data presented in this work may be a useful guideline for future experimental and other theoretical studies.

COMPARAÇÃO ENTRE MÉTODOS PARA DETERMINAÇÃO DE CARGAS ATÔMICAS EM SISTEMAS MOLECULARES: A MOLÉCULA N-{N-(PTERINA-7-IL)CARBONILGLICIL}-L-TIROSINA (NNPT)

COMPARISON BETWEEN ATOMIC CHARGE METHODS FOR MOLECULAR SYSTEMS: THE N-{N-(PTERIN-7-YL) CARBONYLGLYCYL}-L-TYROSINE (NNPT) MOLECULE. Selecting a method to compute partial atomic charges is not trivial because different methods usually provide different charge values and there is no consensus on the most useful approach. In this work, Mulliken, MBS, Chelp, Chelpg, MK, Hirshfeld, NPA, DMA and AIM methods were selected to compute atomic charges and electric dipole moment vector of N-{N-(Pterin-7-yl)carbonylglycyl}-L-tyrosine molecule, a ricin inhibitor which has different types of bonds and chemical environments. While MBS and DMA methods provided the most chemically consistent charges according to atomic electronegativity and electron resonance effects criteria, Chelp, Chelpg and MK had the worst performances. Atomic charges and dipole moment calculated by the Hirshfeld method had the smallest magnitudes, a well-known behavior. Despite the differences among atomic charges predicted by all methods, the direction of the dipole moment vector was essentially the same. Further charge calculations using different basis sets and quantum methods indicated that the dependency on this aspect was the highest for Mulliken and Chelp and the lowest for MBS, Hirshfeld and DMA methods. Thus, results point to MBS and DMA as the most suitable methods for computing chemically consistent atomic charges and dipole moment vectors of similar systems for different applications; e.g., molecular dynamics.

Molecular weight calculator for organic compounds in biotechnology

Automated calculation of molecular weight of chemical compounds would provide savings in time and effort, especially in handling large number of compounds common in chemical or biotechnology workflow. In this work, a molecular weight calculator was developed using MATLAB and is capable of handling the chemical elements: carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur that constitute organic compounds common in biotechnology. Such compounds would typically come across as either substrates or products of fermentation, where automated calculation of molecular weight would feed into mass/charge calculations that facilitate workflow involving their mass spectrometric detection. Specifically, chemical formulas of molecular ion are necessary information for identifying particular mass peaks in mass spectrometry, to which automated molecular weight calculation would greatly simplify peak identification. Thus, the molecular weight calculator developed in this work could be used as a subroutine for more complex software that provides identification of mass peaks in mass spectrometry workflow detecting organic compounds in fermentation.

Molecular weight calculator for organic compounds in biotechnology

Automated calculation of molecular weight of chemical compounds would provide savings in time and effort, especially in handling large number of compounds common in chemical or biotechnology workflow. In this work, a molecular weight calculator was developed using MATLAB and is capable of handling the chemical elements: carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur that constitute organic compounds common in biotechnology. Such compounds would typically come across as either substrates or products of fermentation, where automated calculation of molecular weight would feed into mass/charge calculations that facilitate workflow involving their mass spectrometric detection. Specifically, chemical formulas of molecular ion are necessary information for identifying particular mass peaks in mass spectrometry, to which automated molecular weight calculation would greatly simplify peak identification. Thus, the molecular weight calculator developed in this work could be used as a subroutine for more complex software that provides identification of mass peaks in mass spectrometry workflow detecting organic compounds in fermentation.

Convenient One-Pot Four-Component Synthesis of 6,8-Disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones via a Triple Mannich Reaction

An efficient and simple one-pot four-component protocol has been developed and performed for the synthesis of 6,8-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones, involving a triple Mannich reaction of 6-amino-2-(ethylthio)pyrimidin-4(3H)-one, formaldehyde, primary amines, and alcohols. Secondary amines were also utilised instead of alcohols as Mannich nucleophiles, and a variety of functional groups and electronically varied reaction partners were tolerated. This one-pot reaction facilitated the generation of a library of pyrimido[4,5-d]pyrimidin-4(3H)-ones in very good to excellent yields. The regioselectivity of this reaction was investigated using atomic charge calculations, and spectroscopic data confirmed that the triple Mannich products were 6,8-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones rather than the isomeric 3,6-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones. The structures of all compounds synthesised using the triple Mannich reaction were confirmed via spectroscopic and elemental analyses. The reaction mechanism was studied and confirmed by isolation of the intermediate.

The Spectroscopic and theoretical investigations of complex formation of (3E,3'E)-7,7'-(carbonylbis(azanediyl))bis(3-(2-(2-hydroxyphenyl)hydrazono)-4-oxo-3,4-dihydronaphthalene-2-sulfonic acid) with metal cations

A novel azo-dye was isolated by a diazo-coupling reaction and characterized by the elemental analysis, mass spectra, IR and UV-VIS spectroscopy. The processes of complex formation of H4L with some mono-, bis-, and trivalent metal cations were studied by spectrophotometric titration and theoretical modeling. The NBO effective charge calculations indicate a strong covalent character of the coordination bonds at complexation.