Characterization and dating of blue ballpoint pen inks using principal component analysis of UV-Vis absorption spectra, IR spectroscopy, and HPTLC.

The ink of pens and ink extracted from lines on white photocopier paper of 10 blue ballpoint pens were subjected to ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR), and high-performance thin-layer liquid chromatography (HPTLC). The R(f) values and color tones of the bands separated by thin-layer chromatography (TLC) analysis used to classify the writing inks into three groups. The principal component analysis (PCA) investigates the pen responsible for a piece of writing, and how time affects spectroscopy of written ink. PCA can differentiate between pen ink and ink line indicates the influence of solvent extraction process on the results. The PCA loadings are useful in individualization of a questioned ink from a database. The PCA of ink lines extracted at different times can be used to estimate the time at which a questioned document was written. The results proved that the UV-Vis spectra are effective tool to separate blue ballpoint pen ink in most cases rather than IR and HPTLC.

5-substituted pyrimidine L-2'-deoxyribonucleosides: synthetic, quantum chemical, and NMR studies.

As a part of an ongoing medicinal chemistry, we report here the synthesis and structure evaluation of 1-(2-deoxy-3,5-di-O-acetylpentofuranosyl)-5-[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-4H-pyrazol-4-ylidene) pyrimidine-2,4(1H,3H)-dione 5 and 5-[bis(3-methyl-5-oxo-1-phenyl-4,5-dihydro-4H-pyrazol-4-yl)methyl-1-(2-deoxy-3,5-di-O-acetylpentofuranosyl)pyrimidine-2,4(1H,3H)-dione 6 derived from 3',5'-di-O-acetyl-5-formyl-2'-deoxy-ß-L-uridine 1. Base hydrolysis of compounds 1 and 6 furnished their deacetylated analogues in good yields, whereas hydrolysis of 5 was troublesome. Structural features of these molecules are discussed by NMR spectra analyses and density functional theory quantum chemical calculations. The newly synthesized L-analogues show no significant activity against vaccinia and cowpox viruses.

QSTR of the toxicity of some organophosphorus compounds by using the quantum chemical and topological descriptors.

Quantum chemical and topological descriptors of some organophosphorus compounds (OP) were correlated with their toxicity LD(50) as a dermal. The quantum chemical parameters were obtained using B3LYP/LANL2DZdp-ECP optimization. Using linear regression analysis, equations were derived to calculate the theoretical LD(50) of the studied compounds. The inclusion of quantum parameters, having both charge indices and topological indices, affects the toxicity of the studied compounds resulting in high correlation coefficient factors for the obtained equations. Two of the new four firstly supposed descriptors give higher correlation coefficients namely the Heteroatom Corrected Extended Connectivity Randic index ((1)X(HCEC)) and the Density Randic index ((1)X(Den)). The obtained linear equations were applied to predict the toxicity of some related structures. It was found that the sulfur atoms in these compounds must be replaced by oxygen atoms to achieve improved toxicity.

A regio- and stereo-controlled approach to triazoloquinoxalinyl C-nucleosides.

The synthesis of a new series of acyclic triazoloquinoxalinyl C-nucleosides and their transformation to their cyclic analogs are described following protection, activation, and deprotection with subsequent intramolecular nucleophilic substitution protocol. The antibacterial potency of the new compounds was determined using an inhibition zone diameter test. The results show that 3a and 2b exhibit good activity against Escherichiacoli and Candidaalbicans. On the other hand, the cyclic mesylated C-nucleoside 13 showed activity against the Gram-positive bacteria (Staphylococcusaureus) and antifungal activity against C. albicans.