Nucleophilic Molecule Research Articles

Pivotal Role of Mass Spectrometry for the Assessment of Exposure to Reactive Chemical Contaminants: From the Exposome to the Adductome.

A large part of the Human chemical exposome is now well characterized, and its health effects has been widely documented, although precise causal links remain difficult to establish. In parallel, genetic factors only were shown to contribute less than 30% to various pathologies. Therefore, environmental factors may represent the predominant cause of chronic diseases. Mass Spectrometry has been established for many years as a main "gold standard" in this field due to its performances both in sensitivity and selectivity. However, some unstable or highly reactive compounds may escape their detection in the biological samples because of their short half-life although some of their stable metabolites, if any, can be used for the exposure assessment. These electrophilic molecules are known to bind covalently to nucleophilic molecules in the body to form what are commonly called adducts. The study of adducts formed with DNA, proteins or with glutathione, nowadays called adductomics, can provide additional toxicologically relevant information in biomonitoring studies. This review describes this particular part of the reactive exposome and the related mass spectrometric methods developed therein. Three dedicated parts of this review are devoted to the contribution of mass spectrometry respectively to the assessment of DNA modifications, protein modifications, and reaction with glutathione.

A rapid spectrophotometric test for assessing skin sensitization potential of chemicals by using N-acetyl-L-cysteine methyl ester in chemico

ABSTRACT During the key event 1 of skin sensitization defined as covalent binding or haptenization of sensitizer to either thiol or amino group of skin proteins, a sensitizer not only covalently binds with skin proteins but also interacts with nucleophilic small molecules such as glutathione (GSH). Although GSH would not be directly associated with skin sensitization, this interaction may be applied for developing an alternative test method simulating key event 1, haptenization. Thus, the aim of the present study was to examine whether N-acetyl-L-cysteine methyl ester (NACME), a thiol-containing compound, was selected as an electron donor to determine whether NACME reacted with sensitizers. Following a reaction of NACME with a sensitizer in a 96-well plate, the remaining NACME was measured spectrophotometrically using 5,5’-dithio-bis-(2-nitrobenzoic acid) (DTNB). Following the optimization of test conditions with two different vehicles, such as acetonitrile (ACN) and dimethyl sulfoxide (DMSO), 64 test chemicals were tested to determine the predictive capacity of current NACME test method. The results obtained showed, the predictive capacity of 94.6% sensitivity, 88.9% specificity, and 92.2% accuracy utilizing DMSO as a vehicle with a cutoff NACME depletion of 5.85%. The three parameters were also over 85% in case of ACN. These values were comparable to or better than other OECD-approved test methods. Data demonstrated that a simple thiol-containing compound NACME might constitute as a reliable candidate for identifying reactive skin sensitizers, and that this method be considered as practical method as a screening tool for assessing a chemical’s tendency to initiate skin sensitization.

Potential of Organometallic Complex Compounds as Anticancer Drugs: A Review

Cancer is one of the deadliest diseases in the world. Currently, there are various types of anticancer drugs that are used to treat cancer, but they still have various side effects that can interfere with the quality of life of patients. Organometallic complexes (OCOs) are chemical compounds consisting of metal atoms bonded to carbon atoms. OCOs have various potential to be used as anticancer drugs, including their ability to specifically target cancer cells, inhibit cancer cell growth, and reduce the side effects of other anticancer drugs. The mechanism of action of OCOs involves interactions with nucleophilic molecules within the cell, including DNA, RNA, and proteins, as well as the formation of additional platinum products. In this review, we will discuss organometallic compounds that can function as anticancer drugs, such as platinum, ruthenium, iron, carboplatin, and oxaliplatin, which have been shown to be effective in fighting cancer. We will also discuss the mechanism of action of these compounds in cancer cells and the types of cancer cells that can be treated with organometallic compounds.

Understanding the coupling of non-metallic heteroatoms to CO2 from a Conceptual DFT perspective

ContextA Conceptual DFT (CDFT) study has been carry out to analyse the coupling reactions of the simplest amine (CH3NH2), alcohol (CH3OH), and thiol (CH3SH) compounds with CO2 to form the corresponding adducts CH3NHCO2H, CH3OCO2H, and CH3SCO2H. The reaction mechanism takes place in a single step comprising two chemical events: nucleophilic attack of the non-metallic heteroatoms to CO2 followed by hydrogen atom transfer (HAT). According to our calculations, the participation of an additional nucleophilic molecule as HAT assistant entails important decreases in activation electronic energies. In such cases, the formation of a six-membered ring in the transition state (TS) reduces the angular stress with respect to the non-assisted paths, characterised by four-membered ring TSs. Through the analysis of the energy and reaction force profiles along the intrinsic reaction coordinate (IRC), the ratio of structural reorganisation and electronic rearrangement for both activation and relaxation energies has been computed. In addition, the analysis of the electronic chemical potential and reaction electronic flux profiles confirms that the highest electronic activity as well as their changes take place in the TS region. Finally, the distortion/interaction model using an energy decomposition scheme based on the electron density along the reaction coordinate has been carried out and the relative energy gradient (REG) method has been applied to identify the most important components associated to the barriers.MethodsThe theoretical calculation were performed with Gaussian-16 scientific program. The B3LYP-D3(BJ)/aug-cc-pVDZ level was used for optimization of the minima and TSs. IRC calculations has also been carried out connecting the TS with the associated minima. Conceptual-DFT (CDFT) calculations have been carried out with the Eyringpy program and in-house code. The distortion/interaction model along the reaction coordinate have used the decomposition scheme of Mandado et al. and the analysis of the importance of each components have been done with the relative energy gradient (REG) method.

Universal Covalent Grafting Strategy of an Aptamer on a Carbon Fiber Microelectrode for Selective Determination of Dopamine In Vivo.

The chemical information on brain science provided by electrochemical sensors is critical for understanding brain chemistry during physiological and pathological processes. A major challenge is the selectivity of electrochemical sensors in vivo. This work developed a universal covalent grafting strategy of an aptamer on a carbon fiber microelectrode (CFE) for selective determination of dopamine in vivo. The universal strategy was proposed by oxidizing poly(tannic acid) (pTA) to form an oxidized state (pTAox) and then coupling a nucleophilic sulfhydryl molecule of the dopamine-binding mercapto-aptamer with the o-quinone moiety of pTAox based on click chemistry for the interfacial functionalization of the CFE surface. It was found that the universal strategy proposed could efficiently graft the aptamer on a glassy carbon electrode, which was verified by using electroactive 6-(ferrocenyl) hexanethiol as a redox reporter. The amperometric method using a fabricated aptasensor for the determination of dopamine was developed. The linear range of the aptasensor for the determination of dopamine was 0.2-20 μM with a sensitivity of 0.09 nA/μM and a limit of detection of 88 nM (S/N = 3). The developed method has high selectivity originating from the specific recognition of the aptamer in concert with the cation-selective action of pTA and could be easily applicable to probe dopamine dynamics in the brain. Furthermore, complex vesicle fusion modes were first observed at the animal level. This work demonstrated that the covalently grafted immobilization strategy proposed is promising and could be extended to the in vivo analysis of other neurochemicals.

Enhanced visible light-activated gas sensing properties of nanoporous copper oxide thin films

Metal oxide gas sensors are popular chemoresistive sensors. They are used for numerous tasks, including environmental and safety monitoring. Some gas-sensing materials exhibit photo-induced properties that can be utilized for enhanced gas detection by modifying the sensor selectivity and sensitivity when illuminated by light. Here, we present the gas sensing characteristics of highly nanoporous Cu2O thin films towards both electrophilic (NO2) and nucleophilic (C2H5OH, NH3) gas molecules under ambient temperature and modulated by visible light illumination of different colors (red: 632 nm, green: 530 nm, blue: 468 nm). Cu2O films were fabricated by reactive advanced gas deposition (AGD) technology. The surface and structural analysis of the samples confirm the deposition of nanoporous thin films of mixed copper oxide phases. The gas sensing property of Cu2O exhibited expected p-type semiconductor behavior upon electrophilic and nucleophilic gas exposures. Our results show that visible light illumination provides enhanced sensor response.

Does the radical GPRI strongly depend on the population scheme? A comparative study to predict radical attack on unsaturated molecules with the radical general-purpose reactivity indicator.

The reactivity of 22 unsaturated molecules undergoing attack by a methyl radical (⋅CH3) have been elucidated using the condensed radical general-purpose reactivity indicator (condensed radical GPRI) appropriate for relatively nucleophilic or electrophilic molecules. Using the appropriate radical GPRI equation for electrophilic attack or nucleophilic radical attack, seven different population schemes were used to assign the most reactive atoms in each of the 22 molecules. The results show that the condensed radical GPRI is sensitive to the population scheme chosen, but less sensitive than the radical Fukui function. Therefore, the reliability of these methods depends on the population scheme. Our investigation indicates that the condensed radical GPRI is most accurate in predicting the dominant products of the methyl radical addition reactions on a variety of unsaturated molecules when the Hirshfeld, Merz-Singh-Kollman, or Voronoi deformation density population schemes are used. Furthermore, for all populations schemes in the majority of instances where the radical Fukui function failed the radical GPRI was able to identify the most reactive atom under certain reactivity conditions.

Suppression of deep-level traps via semicarbazide hydrochloride additives for high-performance tin-based perovskite solar cells

Tin perovskites with exemplary optoelectronic properties offer potential application in lead-free perovskite solar cells. However, Sn vacancies and undercoordinated Sn ions on the tin perovskite surfaces can create deep-level traps, leading to non-radiative recombination and absorption of nucleophilic O2 molecules, impeding further device efficiency and stability. Here, in this study, a new additive of semicarbazide hydrochloride (SEM-HCl) with a N–C=O functional group was introduced into the perovskite precursor to fabricate high-quality films with a low concentration of deep-level trap densities. This, in turn, serves to prevent undesirable interaction between photogenerated carriers and adsorbed oxygen molecules in the device’s operational environment, ultimately reducing the proliferation of superoxide entities. As the result, the SEM-HCl-derived devices show a peak efficiency of 10.9% with improved device stability. These unencapsulated devices maintain almost 100% of their initial efficiencies after working for 100 h under continuous AM1.5 illumination conditions.Graphical

Density functional theory study of adsorption of organic molecules on ZnO monolayers: Implications for conduction type and electrical characteristics

Graphene-like ZnO monolayer, a typical two-dimensional material, has garnered enormous research attention due to its desirable optoelectronic properties and potential broad applications. However, the difficult in fabricating p-type ZnO material is still undergoing. Herein, the atomic and electronic properties of the adsorption of the selected organic molecules including electrophilic molecule tetracyano-p-quinodimethane (TCNQ) and nucleophilic molecule tetrathiafulvalene (TTF) on ZnO monolayers are carried out by the first-principles calculations. The results indicate that the adsorption of TCNQ on the ZnO monolayer leads to typical p-type doping, with a small gap (Ep) between the lowest unoccupied molecular and the valance band maximum with shallow acceptor states in the middle gap. However, the adsorption of TTF can obtain n-type doping of ZnO monolayer with the large gap (En) between the highest occupied molecular and the conduction band minimum with deep donor states. For TCNQ-ZnO monolayer, it exhibits the enhancement absorb in solar energy. There is a considerable charge transfer and strong non-covalent interaction between TCNQ and ZnO monolayer. The work function of TCNQ-ZnO ML is higher than that of pristine ZnO ML. However, the adsorption of TTF can significantly reduce the work function of ZnO ML, turning it into an n-type conduction semiconductor. Additionally, upon the adsorption of organic molecules, the layer thickness and the interlayer coupling as well as the adsorption concentration can modify the band gap of ZnO, and further tune the conduction type of ZnO. Remarkably, applying electric field can alter the number of hole and further greatly tune the electrical characteristic of TCNQ-ZnO ML. The current results can promote the applications of two-dimensional ZnO in nanoelectronics and optoelectronics.

Montmorillonite K10 Clay Accelerated One‐Pot Multicomponent Synthesis of Substituted 2‐Amino‐3,5‐dicarbonitrile‐6‐phenylsulfanylpyridines: Experimental and Theoretical Investigation

Abstract2‐Amino‐3,5‐dicarbonitrile‐6‐phenylsulfanylpyridines occupy a prominent place among the physiologically and biologically active scaffolds owing to their therapeutic applications in the treatment of Parkinson's disease, asthma, urinary incontinence, kidney disease, the Hepatitis B infections, Creutzfeldt–Jacob disease, cancer, hypoxia/ischemia and epilepsy. A one‐pot, multicomponent condensation of aldehydes, malononitrile, and thiophenol catalyzed by Montmorillonite K10 clay afforded 2‐amino‐3,5‐dicarbonitrile‐6‐phenylsulfanylpyridines in good to excellent yields. All the products could be well characterized on the basis of spectral studies. The catalyst could be recycled three times without affecting the yields and even in the fourth recycling of the catalyst, the yield decreases marginally. This approach manifests environmentally benign feasibility in contexts of enhanced yields, milder conditions, short reaction times, and reusability of the catalyst. A theoretical study of a synthesized compound at the B3LYP/6–31 + G (d) level is additionally reported. Following the computation of the fundamental vibrational wavenumbers and intensities, it became evident that the observed and calculated wavenumbers were in perfect accord. Employing the same DFT level, Frontier molecular orbital (HOMO‐LUMO) energies, global reactivity descriptors, and molecular electrostatic potential were estimated for assessing the reactivity and possible sites for electrophilic and nucleophilic molecules. The outcomes prove that the compound exhibits significant kinetic stability.

Methimazole, an Effective Neutralizing Agent of the Sulfur Mustard Derivative 2-Chloroethyl Ethyl Sulfide.

Sulfur mustard (SM), designated by the military as HD, is a highly toxic and dangerous vesicant that has been utilized as a chemical warfare agent since World War I. Despite SM's extensive history, an effective antidote does not exist. The effects of SM are predominantly based on its ability to alkylate important biomolecules. Also, with the potential for a fraction of SM to remain unreacted up to days after initial contact, a window of opportunity exists for direct neutralization of unreacted SM over the days following exposure. In this study, we evaluated the structure-activity relationship of multiple nucleophilic molecules to neutralize the toxic effects of 2-chloroethyl ethyl sulfide (CEES), a monofunctional analogue of SM, on human keratinocyte (HaCaT) cells. Cell viability, relative loss of extracellular matrix adhesions, and apoptosis caused by CEES were measured via MTT, cell-matrix adhesion (CMA), and apoptosis protein marker assays, respectively. A set of five two-carbon compounds with various functional groups served as a preliminary group of first-generation neutralizing agents to survey the correlation between mitigation of CEES's toxic effects and functional group nucleophilicity. Apart from thioacids, which produced additive toxicity, we generally observed the trend of increasing protection from cytotoxicity with increasing nucleophilicity. We extended this treatment strategy to second-generation agents which contained advantageous structural features identified from the first-generation molecules. Our results show that methimazole (MIZ), a currently FDA-approved drug used to treat hyperthyroidism, effectively reduced cytotoxicity, increased CMA, and decreased apoptosis resulting from CEES toxicity. MIZ selectively reacts with CEES to produce 2-(2-(ethylthio)ethylthio)-1-methyl-1H-imidazole (EEMI) in media and cell lysate treatments resulting in the reduction of toxicity. Based on these results, future development of MIZ as an SM therapeutic may provide a viable approach to reduce both the immediate and long-term toxicity of SM and may also help mitigate slower developing SM toxicity due to residual intact SM.

Nucleophilic covalent ligand discovery for the cysteine redoxome.

With an eye toward expanding chemistries used for covalent ligand discovery, we elaborated an umpolung strategy that exploits the 'polarity reversal' of sulfur when cysteine is oxidized to sulfenic acid, a widespread post-translational modification, for selective bioconjugation with C-nucleophiles. Here we present a global map of a human sulfenome that is susceptible to covalent modification by members of a nucleophilic fragment library. More than 500 liganded sulfenic acids were identified on proteins across diverse functional classes, and, of these, more than 80% were not targeted by electrophilic fragment analogs. We further show that members of our nucleophilic fragment library can impair functional protein-protein interactions involved in nuclear oncoprotein transport and DNA damage repair. Our findings reveal a vast expanse of ligandable sulfenic acids in the human proteome and highlight the utility of nucleophilic small molecules in the fragment-based covalent ligand discovery pipeline, presaging further opportunities using non-traditional chemistries for targeting proteins.

Weak Bonds, Strong Effects: Enhancing the Separation Performance of UiO-66 toward Chlorobenzenes via Halogen Bonding

Halogen bonding (HaB) is a weak interaction that assists in the recognition of nucleophilic molecules. However, HaB elements are currently under-investigated as a part of functional materials in separation science. Herein, we develop a novel approach for introducing HaB elements into UiO-66 to fine-tune the adsorption properties toward chlorobenzenes (CBs). A series of UiO-66 containing various contents of 2-iodoterephtalic acid (I-TA) (0%, 33%, 50%, 67%, and 100%) was prepared, characterized, and applied for the selective removal of CB contaminants from nonchlorinated aromatic analogues that cannot be separated by common distillation. Investigation of the structure–property relationship revealed that the highest adsorption capacity was achieved in the case of UiO-66 loaded with 50% I-TA (UiO-66-Iopt), and this was attributed to the balance between the number of HaB elements and the surface area of the UiO-66 structure. According to density functional theory calculations, the formation of a conjugate between dichlorobenzene and UiO-66-Iopt was more energetically favorable (up to 1.7 kcal/mol) than that of the corresponding conjugate with UiO-66. The formation of HaBs was experimentally verified by UV–vis, Raman, and X-ray photoelectron spectroscopies. To obtain functional materials for separation applications, waste polyethylene terephthalate (PET) was used as a support and feedstock for the surface-assisted growth of UiO-66-Iopt. The as-prepared PET@UiO-66-Iopt exhibited a close-to-perfect selectivity and reusability for the separation of a wide range of CBs from nonchlorinated aromatic analogues.

Direct Observation of the Dynamics of Ylide Solvation by Hydrogen-bond Donors Using Time-Resolved Infrared Spectroscopy.

The photoexcitation of α-diazocarbonyl compounds produces singlet carbene intermediates that react with nucleophilic solvent molecules to form ylides. The zwitterionic nature of these newly formed ylides induces rapid changes in their interactions with the surrounding solvent. Here, ultrafast time-resolved infrared absorption spectroscopy is used to study the ylide-forming reactions of singlet carbene intermediates from the 270 nm photoexcitation of ethyl diazoacetate in various solvents and the changes in the subsequent ylide–solvent interactions. The results provide direct spectroscopic observation of the competition between ylide formation and C–H insertion in reactions of the singlet carbene with nucleophilic solvent molecules. We further report the specific solvation dynamics of the tetrahydrofuran (THF)-derived ylide (with a characteristic IR absorption band at 1636 cm–1) by various hydrogen-bond donors and the coordination by lithium cations. Hydrogen-bonded ylide bands shift to a lower wavenumber by −19 cm–1 for interactions with ethanol, −14 cm–1 for chloroform, −10 cm–1 for dichloromethane, −9 cm–1 for acetonitrile or cyclohexane, and −16 cm–1 for Li+ coordination, allowing the time evolution of the ylide–solvent interactions to be tracked. The hydrogen-bonded ylide bands grow with rate coefficients that are close to the diffusional limit. We further characterize the specific interactions of ethanol with the THF-derived ylide using quantum chemical (MP2) calculations and DFT-based atom-centered density matrix propagation trajectories, which show preferential coordination to the α-carbonyl group. This coordination alters the hybridization character of the ylidic carbon atom, with the greatest change toward sp2 character found for lithium-ion coordination.

Synthesis and Structural Characterization of a New 1,2,3-Triazole Derivative of Pentacyclic Triterpene

The new 30-substituted triazole derivative of 3,28-O,O′-diacetylbetulin was obtained in the copper(I) catalyzed azide-alkyne cycloaddition (CuAAC). The title compound was characterized by NMR, IR, HR-MS, and X-ray diffraction techniques. The X-ray diffraction study showed that the 1,2,3-triazole derivative crystallizes in the orthorhombic space group P212121, Z = 4, and unit cell parameters are as follows a = 9.4860(10) Å, b = 13.9440(2) Å, and c = 30.2347(4) Å. The molecular packing is stabilized by intermolecular hydrogen interactions C-H…O. The Hirshfeld surface analysis showed the presence of the O…H interactions with a percentage of the 16.5% in the total Hirshfeld area. The MEP analysis showed that the nucleophilic regions are located near the oxygen atoms of the acyl and carbonyl groups of betulin moiety and the sulfur atom in the triazole linker. The HOMO and LUMO orbitals are located near the triazole moiety. The obtained results indicated that this new betulin derivative is more reactive with electrophilic than nucleophilic molecules.

Antimicrobial and antioxidant effect of lyophilized Fucus spiralis addition on gelatin film during refrigerated storage of mackerel

Lyophilized alga Fucus spiralis powder was incorporated into a gelatin-based film and employed as a packaging system for mackerel ( Scomber scombrus ) muscle portions throughout a 9-day refrigerated storage period at 4 °C. In global terms, a progressive loss of quality could be observed in fish muscle with increasing storage time. Comparisons between batches allowed us to conclude an inhibitory effect of F. spiralis -containing films on microbial activity (assessment of aerobes, psychrotrophs, and proteolytic bacteria) and on lipid hydrolysis (as determined by free fatty acid formation) in mackerel muscle. The presence of the lyophilized macroalga in the packaging film also led to a higher retention of primary (peroxides) and secondary (thiobarbituric acid reactive substances) lipid oxidation compounds, while the formation of fluorescent compounds (interaction compounds between lipid oxidation compounds and nucleophilic molecules present in the fish muscle) decreased. Both antimicrobial and antioxidant effects were more intense when the concentration of alga in the packaging film was increased. The preservative effect resulting from the presence of F. spiralis in gelatin-based films demonstrates the potential employment of such bioactive films to improve the retention of fish quality and enhance its commercial value. • Lyophilized Fucus spiralis was incorporated into a gelatin packaging film. • F. spiralis in the packaging film inhibited free fatty acid formation in mackerel. • F. spiralis inhibited aerobes, psychrotrophs, and proteolytic bacteria in fish muscle. • F. spiralis in the packaging film inhibited fluorescent compound formation. • Superior retention of primary and secondary lipid oxidation compounds was observed.

Sonochemical Reaction of Bifunctional Molecules on Silicon (111) Hydride Surface

While the sonochemical grafting of molecules on silicon hydride surface to form stable Si–C bond via hydrosilylation has been previously described, the susceptibility towards nucleophilic functional groups during the sonochemical reaction process remains unclear. In this work, a competitive study between a well-established thermal reaction and sonochemical reaction of nucleophilic molecules (cyclopropylamine and 3-Butyn-1-ol) was performed on p-type silicon hydride (111) surfaces. The nature of surface grafting from these reactions was examined through contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Cyclopropylamine, being a sensitive radical clock, did not experience any ring-opening events. This suggested that either the Si–H may not have undergone homolysis as reported previously under sonochemical reaction or that the interaction to the surface hydride via a lone-pair electron coordination bond was reversible during the process. On the other hand, silicon back-bond breakage and subsequent surface roughening were observed for 3-Butyn-1-ol at high-temperature grafting (≈150 °C). Interestingly, the sonochemical reaction did not produce appreciable topographical changes to surfaces at the nano scale and the further XPS analysis may suggest Si–C formation. This indicated that while a sonochemical reaction may be indifferent towards nucleophilic groups, the surface was more reactive towards unsaturated carbons. To the best of the author’s knowledge, this is the first attempt at elucidating the underlying reactivity mechanisms of nucleophilic groups and unsaturated carbon bonds during sonochemical reaction of silicon hydride surfaces.

Effects of Substitution on Cytotoxicity of Diphenyl Ditelluride in Cultured Vascular Endothelial Cells

Among organic–inorganic hybrid molecules consisting of organic structure(s) and metal(s), only few studies are available on the cytotoxicity of nucleophilic molecules. In the present study, we investigated the cytotoxicity of a nucleophilic organotellurium compound, diphenyl ditelluride (DPDTe), using a cell culture system. DPDTe exhibited strong cytotoxicity against vascular endothelial cells and fibroblasts along with high intracellular accumulation but showed no cytotoxicity and had less accumulation in vascular smooth muscle cells and renal epithelial cells. The cytotoxicity of DPDTe decreased when intramolecular tellurium atoms were replaced with selenium or sulfur atoms. Electronic state analysis revealed that the electron density between tellurium atoms in DPDTe was much lower than those between selenium atoms of diphenyl diselenide and sulfur atoms of diphenyl disulfide. Moreover, diphenyl telluride did not accumulate and exhibit cytotoxicity. The cytotoxicity of DPDTe was also affected by substitution. p-Dimethoxy-DPDTe showed higher cytotoxicity, but p-dichloro-DPDTe and p-methyl-DPDTe showed lower cytotoxicity than that of DPDTe. The subcellular distribution of the compounds revealed that the compounds with stronger cytotoxicity showed higher accumulation rates in the mitochondria. Our findings suggest that the electronic state of tellurium atoms in DPDTe play an important role in accumulation and distribution of DPDTe in cultured cells. The present study supports the hypothesis that nucleophilic organometallic compounds, as well as electrophilic organometallic compounds, exhibit cytotoxicity by particular mechanisms.

Quantum Calculations of VX Ammonolysis and Hydrolysis Pathways via Hydrated Lithium Nitride.

Recently, lithium nitride (Li3N) has been proposed as a chemical warfare agent (CWA) neutralization reagent for its ability to produce nucleophilic ammonia molecules and hydroxide ions in aqueous solution. Quantum chemical calculations can provide insight into the Li3N neutralization process that has been studied experimentally. Here, we calculate reaction-free energies associated with the Li3N-based neutralization of the CWA VX using quantum chemical density functional theory and ab initio methods. We find that alkaline hydrolysis is more favorable to either ammonolysis or neutral hydrolysis for initial P-S and P-O bond cleavages. Reaction-free energies of subsequent reactions are calculated to determine the full reaction pathway. Notably, products predicted from favorable reactions have been identified in previous experiments.

Analysis and comparison of metal-doped on Graphene-Genistein using QM/MM calculations

Genistein (5,7,4′-trihydroxyisoflavone) is an isoflavone abundantly found in soy and other legumes and acts as a selective estrogen receptor modulator (SERM). When testing for similar abilities among other flavonoids, it has been found to be a strong topoisomerase inhibitor. Similar to some high-dose chemotherapy drugs, it was strongly toxic to normal cells. In this study, the adsorption of genistein on the surface of exclusive graphene and Ni, Ti, Cr, and Se-doped graphene was theoretically evaluated by means of density functional theory calculation. Initially, we varied the position of genistein from the surface of pristine and decorated graphene by changing the distances between (1-5 Å) and gained the Ead and Egap for each situation. Our calculation indicated that adsorption energies (Ead) of pristine genistein to graphene with Ni decorated graphene, Ti- decorated graphene, and Cr-decorated graphene and Se-decorated graphene are: 954.984, 318.168, 797.480, 946.725, 958.154 kcal/mole, respectively, and the calculated values of adsorption energy in the equilibrium distance (de=3.918OA.) of genistein to Ni-decorated graphene reveal that apparently genistein- Ni-decorated graphene as the most energetically favorable position was correctly selected in comparison with other atom -decorated graphene. In consequence, we explain the density of states (Doss) and frontier molecular orbitals HOMO and LUMO for Ni-decorated graphene and complexes with genistein; therefore, data confirmed that a positive charge of Ni-decorated graphene for nucleophile molecules could be achieved.