Yassin A. Jeilani

Spelman College · Department of Chemistry and Biochemistry

Understanding of the abiotic formation of nucleosides under geochemical conditions is currently a major scientific challenge. In this study, free radical pathways for formation of RNA nucleosides with canonical nucleobases are proposed for the first time. The pathways proceed with relatively low energy barriers for the formation of ribose as well a...

The development of fluorescent probe(s) for naked eye analyte detection is an emerging area of research. Such probes can be judiciously engineered to realize analyte specific response with high sensitivity and broad applicability. Herein, we report reversible acid-base sensing ability of a donor-acceptor-donor (D-A-D) type thioxanthone-based lumino...

The geometrical evolution, electronic structure and thermodynamic stability of a series of singly-doped SinP and doubly-doped SinP2 silicon clusters with n = 1-10, in the neutral, cationic and anionic states were systematically investigated using DFT computations. The global minimum structures were identified using different search approaches. The...

The reaction pathways for the prebiotic formation of nucleobases are complex and lead to the formation of a mixture of products. In the past 50 years, there has been a concerted effort for identifying a unified mechanism for the abiotic origin of the biomolecules but with little success. In the present theoretical study, we identified two prominent...

Prebiotic building blocks for the formation of biomolecules are important in understanding the abiotic origin of biomolecules. However, there is a limited choice of the building blocks as precursors for the biomolecules. Acetylene (HCCH) is found in Titan's atmosphere and is an abiotic-precursor of pyrimidine bases. HCCH reacts with urea to form bo...

The prebiotic formation of nucleobases, the building blocks of RNA/DNA, is of current interest. Highly reactive radical species present in the atmosphere under irradiation have been suggested to be involved in the prebiotic synthesis of nucleobases from formamide (FM). We studied several free radical reaction pathways for the synthesis of pyrimidin...

RationaleHexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is an explosive compound that finds a wide range of military and civilian applications. RDX has been a target in environmental matrices by gas chromatography/tandem mass spectrometry (GC/MS/MS). MS/MS in negative chemical ionization (NCI) mode of RDX provides important fragmentation patterns th...

Fragmentation mechanisms of estradiol and trimethylsilyl (TMS)-derivatized estradiol were studied by triple quadrupole tandem mass spectrometry (MSMS) and density functional theory (DFT) at B3LYP/6-311G(d,p) level. Collision induced dissociations (CID) of estradiol give product ions that are associated with the cleavage of B, C and D rings. Charact...

Prebiotic formation of triazines from urea was studied using density functional theory methods with the aim of understanding some of the neutral precursors that can lead to a mixture of triazines. The proposed mechanisms are based on free radical routes without solvent requirements that are appropriate for prebiotic scenarios occurring under highly...

Modeling the complicated chemical reactions in the interstellar medium and surface materials of Titan is nontrivial. Since both the atmosphere and the surface are rich in organic molecules, the chemistry may have important implications for the origin of biomolecules. Prebiotic synthesis of DNA nucleobases from simple molecules such as formamide has...

Multiwall carbon nanotubes (MWCNTs, 1–3 μM in length and 20–25 nm in diameter) were initially functionalized with a 2,2′:6′2″-terpyridine-chelated ruthenium(II) complex by covalent amidation. The resulting functionalized ruthenium MWCNTs (RuMWCNTs, 1–2 μM in length and 10–20 nm in diameter) were characterized by thermogravimetric analysis, X-ray ph...

In this study, an Artificial Neural Network (ANN) was developed as a predictive tool for identifying optimal remediation conditions for groundwater contaminants that include selected metals found at coal mining sites. The ANN was developed from a previous field data obtained from a bioremediation project at an abandoned mine at Cane Creek in Alabam...

Substituted silyl ethers of o-bromobenzyl alcohols and the derived o-silylbenzyl alcohols were used to transfer allyl and benzyl groups from silicon to the electrophiles benzaldehyde and benzophenone in excellent yields. γ-Oxidosilane intermediates (and possibly hypercoordinated silicon intermediates) are postulated.

This is the first ab initio study of the energetics of the fragmentation mechanisms of phthalate, by mass spectrometry, leading to protonated phthalic anhydride (m/z 149). Phthalates fragment by two major pathways; namely, the McLafferty + 1 rearrangement and the loss of alkoxy. Both pathways involve a carbonyl oxygen attack to the ortho-carbonyl c...

The fragmentation mechanisms of progesterone have been studied by triple quadrupole tandem mass spectrometry (MSMS) and density functional theory (DFT). Mechanisms leading to major product ions are proposed. The data suggest that progesterone fragments preferentially via hydrogen and other rearrangements lead to neutral losses. These fragmentations...

We report the first positive chemical ionization (PCI) fragmentation mechanisms of phthalates using triple-quadrupole mass spectrometry and ab initio computational studies using density functional theories (DFT). Methane PCI spectra showed abundant [M + H](+), together with [M + C(2)H(5)](+) and [M + C(3)H(5)](+). Fragmentation of [M + H](+), [M +...

Fragmentation of fluorotelomer alcohols were studied by triple quadrupole mass spectrometry in Electron Ionization (EI), Positive Chemical Ionization (PCI), and Negative Chemical Ionization (NCI). The selected Fluorotelomer alcohols included 2-(perfluorohexyl)ethanol, 2-(perfluorooctyl)ethanol, and 2-(perfluorodecyl)ethanol. Spectra of these alcoho...

Phthalate fragmentation mechanism was studied by Collision Induced Dissociation (CID) using triple quadrupole mass spectrometer. A total of six phthalate esters targeted in the Environmental Protection Agency method number 506 were studied. Mass spectrum of each compound was obtained and then precursor ion scan experiments were performed by setting...

A sequential anaerobic-aerobic biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was studied. The results demonstrated that: (i) a complete degradation of RDX was achieved within 20 days using a consortium of bacteria from a wastewater activated sludge, (ii) RDX degradation did not occur under aerobic conditions alone, (iii) RDX-degra...