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The structure and stability of the compounds MRg+ and MRgF (Rg=Ar, Kr, and Xe; M=Co, Rh, and Ir) were investigated using the B3LYP, MP2, MP4(SDQ) and CCSD(T) methods. We reported the geometry, vibrational frequencies and thermodynamics properties of these compounds. A series of theoretical methods on the basis of wavefunction analysis, including natural bond orbitals, atoms in molecules, electron localization function, and energy decomposition analysis, were performed to explore bonding nature of the M−Rg and Rg−F bonds. These bonds are mainly noncovalent, the metal weakly interacts with Rg in MRg+, but their interaction is much stronger in MRgF. The neutral molecule MRgF can be well described by the Lewis structure [MRg]+F−.

A model of reversible and quasi-reversible electrode reaction of dissolved redox couple is developed for the staircase voltammetry and the twin electrode thin layer cell. It is assumed that the neutral molecule is oxidized to a monovalent cation. The calculations were performed for the absence of supporting electrolyte and for its various concentrations. The influence of migration of cations and of IRΩ drop on the peak currents and peak potentials was investigated. Also, the kinetically controlled electrode reactions were simulated. These reactions can be distinguished from the reactions influenced by the resistance in the solution.

Regarding the relation of halitosis with oral infections and its effects on social relations between humans, the present study investigated the positive effects of probiotics on prevention or treatment of halitosis. The causative agents of halitosis are volatile sulphur compounds (VSCs), and halitosis is divided into oral and non-oral types according to the source of the VSCs. H2S and CH3SH are two main halitosis metabolites-produced following the degradation of proteins by bacteria in the mouth-however, CH3SCH3 has a non-oral origin, and is a blood neutral molecule. Just as much as halitosis is important in medicine, its psychological aspects are also considered, which can even lead to suicide. Today, the use of probiotics as a new therapeutic in many roles is in progress. Most probiotics are used for the treatment of gastrointestinal tract disorders, but various studies on the alleviation of halitosis by use of probiotics have reported satisfactory results. The genera Lactobacillus, Streptococcus and Weissella are among the most useful probiotics for the prevention or treatment of halitosis in the oral cavity.

It is widely accepted that solubility-pH profiles of ionizable compounds follow the Henderson-Hasselbalch equation. However, several studies point out that compounds often undergo additional processes in saturated solutions, such as sub-micellar oligomerization, micellar aggregation, or drug-buffer complexation among others, which make the experimental profiles deviate from the behavior predicted by the Henderson-Hasselbalch equation. Often, the presence of additional processes is supported by the analysis of experimental data through solubility computer programs. However, the purpose of this work is to experimentally prove the aggregation phenomena for a series of bases for which deviations from the theoretical profile have been observed. To this end, five monoprotic bases (lidocaine, maprotiline, cyproheptadine, bupivacaine, and mifepristone) susceptible to form ionic aggregates in solution have been selected, and mass spectrometry has been the technique of choice to prove the presence of aggregation. High declustering potentials have been applied to prevent aggregates from forming in the ionization source of the mass spectrometer. In addition, haloperidol has been used as a negative control since according to its profile, it is not suspected to form ionic aggregates. In all instances, except for haloperidol, the analysis of the saturated solutions revealed the presence of mixed-charged dimers (aggregates formed by a neutral molecule and a charged one) and even trimers in the case of mifepristone and bupivacaine. For lidocaine, the most soluble of the compounds, the presence of neutral aggregates was also detected. These experiments support the hypothesis that the simple Henderson-Hasselbalch equation may explain the solubility-pH behavior of certain compounds, but it can be somewhat inaccurate in describing the behavior of many other substances.

Plants accumulate silicon in their tissues as amorphous silica. The form of silicon taken up by plants is silicic acid, a neutral molecule that passes through membrane channels with water. After seminal work on rice identified an aquaporin that appeared to mediate the passage of silicic acid, several papers followed and classified similar channels (referred to as “transporters”) in a number of plant species. These channels have been described as essential for silicon uptake and specific for the metalloid. Herein, we critically review the published data on the characterisation of one channel in particular, Lsi1, and identify possible caveats in results and limitations in methods used. Our analysis does not support the suggestion that the identified channels are specific for silicic acid. Computational analyses of the size of the Lsi1 pore additionally suggest that it may not play a significant role in mediating the movement of silicic acid in planta. We suggest that to avoid further confusion, channels currently implicated in the transport of silicic acid in planta are not referred to as silicon-specific transporters. Future research including the use of molecular dynamics simulations will enable the unequivocal identification of channels involved in silicon transport in plants.

The process of dissociative electron attachment (DEA) to molecules with several vibrational degrees of freedom is usually treated in the approximation of the local potential for the description of the nuclear motion. We develop the nonlocal complex potential theory to treat the dissociation dynamics when there is more than one vibrational mode in the neutral molecule. We demonstrate the application of the multimode nonlocal theory to a generic molecule of the type $\mathrm{C}{Y}_{3}X$, where Y denotes the H or F atom and X denotes the halogen atom, with the inclusion of symmetric C--X stretch and $\mathrm{C}{Y}_{3}$ deform (``umbrella'') vibrational modes. We present results for the dependence of DEA cross sections on the electron energy and vibrational energy for the ${\mathrm{CF}}_{3}\mathrm{Cl}$ molecule in the two-mode approximation. The 1.5 eV peak in the DEA cross section is well described in the one-mode approximation. However, inclusion of additional modes is required to explain the experimentally observed low-energy peak in the DEA cross section at the vibrational temperature ${T}_{v}=800$ K.

Complex formation of α-, β-, and γ-cyclodextrins with sulfasalazine in biologically relevant buffer solutions (pH 1.2 and 7.4) was studied. Formation of inclusion complexes of 1 : 1 stoichiometry between the drug and cyclodextrins was revealed. The ionization state of sulfasalazine more strongly affects the complex formation than does the structure of cyclodextrins. Compared with a neutral molecule, sulfasalazine anionic species forms with cyclodextrins more stable complexes, which are essentially stabilized by possible surface interactions.

H2 is the most abundant molecule in the universe. It is also the only neutral molecule whose energy levels can be precisely calculated based on quantum electrodynamics and fundamental physical constants without using any adjustable parameters. Precision spectroscopy of the hydrogen molecule is of great importance in astrophysical observation and in testing fundamental physics as well. Here we review the theoretical and experimental spectroscopy studies of the electronic ground state of the hydrogen molecule. The frequency of the R(1) transition in the V =2-0 band of HD is also determined with an accuracy of 5×10−10, which is the most precisely measured ro-vibrational transition of the hydrogen molecule to date. By comparing the calculated and experimental results, we present perspectives of the precision spectroscopy of the hydrogen molecule in the determination of fundamental physical constants such as the proton-electron mass ratio.

We demonstrate a proof of principle for a new approach in the development of a drug delivery system. A positively charged prodrug (phenol) can form a stable inclusion complex with CB[7], which enables more efficient delivery of the prodrug. After photochemical transformation (photoactivation) inside the complex, an active drug quinone methide (QM) is formed and released from the complex, since it is a neutral molecule and forms a less stable complex with CB[7].

Self-assembly post-modification has proven to be an efficient strategy to build higher-order supramolecular architectures and functional materials. In this study, we successfully realized the construction of a new family of neutral supramolecular polymeric films containing well-defined metallacycles as the main scaffolds through combination of coordination-driven self-assembly with post-electropolymerization. The obtained neutral polymeric materials were fully characterized by the cyclic voltammogram (CV), SEM, and TEM. The thickness of the films was able to be well regulated by the number of scanning cycles. Moreover, we found that the shape of the metallacycles and the number of triphenylamine moieties played important roles in the formation of the final polymer films. We believe that the introduction of the neutral metallacycles into the final polymer structures not only enriches the library of supramolecular polymeric films but also provides a new platform to study neutral molecule detection, separation, and capture.

An accurate yet computationally very efficient and formally well justified approach to calculate molecular ionization potentials is presented and tested. The first as well as higher ionization potentials are obtained as the negatives of the Kohn-Sham eigenvalues of the neutral molecule after adjusting the eigenvalues by a recently [Gorling Phys. Rev. B 2015, 91, 245120] introduced potential adjustor for exchange-correlation potentials. Technically the method is very simple. Besides a Kohn-Sham calculation of the neutral molecule, only a second Kohn-Sham calculation of the cation is required. The eigenvalue spectrum of the neutral molecule is shifted such that the negative of the eigenvalue of the highest occupied molecular orbital equals the energy difference of the total electronic energies of the cation minus the neutral molecule. For the first ionization potential this simply amounts to a Delta SCF calculation. Then, the higher ionization potentials are obtained as the negatives of the correspondingly shifted Kohn-Sham eigenvalues. Importantly, this shift of the Kohn-Sham eigenvalue spectrum is not just ad hoc. In fact, it is formally necessary for the physically correct energetic adjustment of the eigenvalue spectrum as it results from ensemble density-functional theory. An analogous approach for electron affinities is equally well obtained and justified. To illustrate the practical benefits of the approach, we calculate the valence ionization energies of test sets of small- and medium-sized molecules and photoelectron spectra of medium-sized electron acceptor molecules using a typical semilocal (PBE) and two typical global hybrid functionals (B3LYP and PBE0). The potential adjusted B3LYP and PBE0 eigenvalues yield valence ionization potentials that are in very good agreement with experimental values, reaching an accuracy that is as good as the best G(0)W(0) methods, however, at much lower computational costs. The potential adjusted PBE eigenvalues result in somewhat less accurate ionization energies, which, however, are almost as accurate as those obtained from the most commonly used G(0)W(0) variants.

Majority of the known interstellar cations are protonated species believed to be the natural precursors for their corresponding neutral analogues formed via the dissociative recombination process. The protonation of a neutral species can occur in more than one position on the molecular structure thus resulting in more than one proton binding energy value and different protonated species for the same neutral species. In the present work, ab initio quantum calculations are employed to calculate accurate proton binding energies for over 100 neutral interstellar molecules of which majority of the neutral molecules are protonated in more than one position. From the results, protonated species resulting from a high proton binding energy prefers to remain protonated rather than transferring a proton and returning to its neutral form as compared to its analogue that gives rise to a lower proton binding energy (PBE) from the same neutral species. For two protonated species resulting from the same neutral molecule, the one that results in a higher PBE is more stable as compared to its counterpart that is responsible for the lower PBE for the same neutral species. Here, the most stable species are highlighted for all the systems considered.

Biphenyls are an important intermediate in organic chemistry which constitutes the structural moiety of a wide range of compounds with profound pharmacological activity. Being a neutral molecule (due to absence of the active functional moiety on it), biphenyls are required to be functionalized i.e. introduction of active group on it. Thus, the substituted biphenyls can be used for synthesis or condensation of another active group with itself which are pharmacologically significant thereby forming the compounds with altogether new activity. Initially, biphenyls were widely used as intermediates in chemical synthesis and pesticides in the form of PCBs (polychlorinated biphenyls). But with the emerging trends in the synthetic chemistry, a number of derivatives are obtained which are of therapeutic significance. This review is summarized to know about synthesis of biphenyl and its derivatives as well as various biphenyl analogs that has potential to act against number of disease and disorders.

Two N-(2-(bis(pyridin-2-ylmethyl)amino)ethyl)quinoline-2-carboxamides and two N-(2-(bis(quinolin-2-ylmethyl)amino)ethyl)quinoline-2-carboxamides have been synthesized. These structures contain five nitrogen atoms that can form coordinate bonds with metal ions such as Mn(II) and Fe(II). An additional coordinating bond can be formed between the metal ion and a neutral molecule of nitric oxide (NO). The resultant complexes are potentially useful agents for targeted delivery of NO to in vivo biological sites such as tumors, where the NO is released upon irradiation with long-wavelength light. Initial work involving the synthesis and characterization of these analogues is reported here.

Enhancing the sensitivity of colorimetric detection in paper-devices is a quintessential step in achieving frugal diagnosis. Here, we demonstrate an effective way of improving the detection sensitivity of paper-based devices, as mediated by electro-kinetic mechanisms. By directly employing blood plasma, we investigate the electro-kinetic clustering of glucose, a neutral molecule in paper devices. Under the influence of uniform electric field, dispersed glucose gets accumulated in the paper strips. Due to the combination of electroosmotic flow and electrophoretic migration, we achieve two-fold increase in the colour intensity for both normal and diabetic samples. This approach is robust and possesses better sensitivity than conventional colorimetric assays and can be easily extended to other body fluid based diagnosis. These results may turn out to be of profound importance in improving the quality of pathological diagnosis in low-cost paper-based point-of-care devices deployed in resourcelimited settings

Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one-electron oxidation of redox-active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono- and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol-1 . While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device.

Ultrafast molecular rotors (UMRs) are reported to be one of the best fluorescent sensors to study different microenvironments, including biomolecules. In the present work, we have explored the possibility of application of a julolidine-based neutral UMR, 9-(2,2-dicyano vinyl) julolidine (DCVJ), as a DNA sensor and studied its mode of binding with DNA in detail using spectroscopic and molecular docking techniques. Our spectroscopic studies indicate that association of DCVJ with DNA leads to a very large enhancement in its emission intensity. Detailed investigation reveals that, despite being a neutral molecule, binding of DCVJ with DNA is largely modulated in the presence of salt. Such an unusual salt effect has been explained by invoking the ion-dipole interaction between DCVJ and the phosphate backbone of DNA. The ion-dipole interaction has also been established by studying the interaction of DCVJ with nucleosides. Detailed time-resolved studies show that the twisting motion around the vinyl bond in DCVJ gets retarded to a great extent because of its association with DNA molecules. Through competitive binding studies, it has also been established that DCVJ also binds to DNA through intercalation. Finally, quantum chemical calculations and molecular docking studies have been performed to confirm the mode of binding of DCVJ with DNA.

Density functional theory (DFT) has been used to investigate the reaction pathways with steam reforming of glycerol under cold plasma conditions. Total energies, energy barriers, and reaction enthalpies at 298.15 K have been calculated at the GGA/PW91/DNP level. The calculation shows that, with the presence of steam, the energy barrier of glycerol conversion is reduced and the conversion from glycerol to H2 and CO is promoted under cold plasma conditions. The formation of syngas was through a multi-step pathway via the conversion of OHCH2CHOH, CH2OH, CH2O, HCO,·and CH3, while the recombination of H generated extra H2. The synthesis of hydrocarbons are from the recombination of·CH3,·CH2, and·CH, which could be primarily generated through glycerol dissociation. The structure of glycerol anion was also studied in this work, and it was less stable than the neutral molecule. The route for the formation of OHCH2CHOH·and CH2OH·from glycerol anion is thermodynamically favorable.

Synopsis The nonlocal complex potential theory is developed to treat the dissociative electron attachment to molecules when more than one vibrational mode is allowed in the neutral molecule. Temperature-averaged cross sections for electron attachment to CF3Cl are obtained assuming two vibrational degrees of freedom.

The chemical reduction of a [3]cumulene ([3]TrTol) has been explored using alkali metals. Mono- and doubly reduced forms of [3]TrTol were isolated as solvent-separated ion pairs with {Na(18-crown-6)THF2 }+ and {K(18-crown-6)THF2 }+ counterions and crystallographically characterized. This allowed analysis of structural parameters of the "naked" anions of [3]TrTol without interference from metal binding. The dianion of [3]TrTol was also isolated as a contact-ion complex with {Cs(18-crown-6)}+ cations, thereby adding the effect of metal coordination to the core. Structural comparisons of anions to the neutral molecule, [3]TrTol, outline monotonic increases in bond-length alternation (BLA) upon stepwise reduction. The greatest BLA value is found for the contact-ion complex, which shows an alternating sequence of short and long carbon-carbon bonds, consistent with the structure of an alkyne. In contrast to studies on tetraphenyl[3]cumulene, the cumulenic framework of [3]TrTol remains planar in all the derivatives.

In the present paper we analyze in detail several properties of the ${\mathrm{MgH}}^{\ensuremath{-}}$ anion and the MgH neutral molecule using accurate ab initio quantum computational methods in order to establish with a higher reliability specific molecular features like the gas-phase electron affinity, the Franck-Condon factors for excitation of the neutral and of its anion to their lower electronic states, and the general feasibility of employing the anion in photodetachment experiments after its confinement in cold ion traps. The calculations suggest that the electron affinity value is in agreement with an existing early experiment and, further, places on it an error bar smaller than that given before. Accurate zero-point-energy corrections are also included in our calculations and their effects discussed.

A new inorganic-organic hybrid compound, [{Cu(phen)2}2(H4W12O40)], was synthesized, and its crystal structure was determined. The Keggin anion H4W12O404− was grafted with two coordination units {Cu(phen)2}, forming an electrically neutral molecule. The antibacterial activity of several polyoxometalate compounds with different anionic structures including the new compound was studied. The results show that the compound 1 can inhibit the growth of Enterococcus faecalis FA2 strains and that antibacterial activity of the polyoxometalate compounds is dependent with component elements of POM but is less relative with the anion structures.

Volume of distribution is one of the most important pharmacokinetic properties of a drug candidate. It is a major determinant of half-life and dosing frequency of a drug. For a similar log P, a basic molecule will tend to exhibit higher volume of distribution than a neutral molecule. Acids often exhibit low volumes of distribution. Although a design strategy against volume of distribution can be advantageous in achieving desirable dosing regimen, it must be well-directed in order to avoid detrimental effects to other important properties. Strategies to increase volume of distribution include adding lipophilicity and introducing basic functional groups in a way that does not increase metabolic clearance.

Recent laboratory experiments using a pulsed Laval nozzle apparatus have shown that reactions between a neutral molecule and the radical OH can occur efficiently at low temperatures despite activation energy barriers if there is a hydrogen-bonded complex in the entrance channel which allows the system to tunnel efficiently under the barrier. Since OH is a major radical in the interstellar medium, this class of reactions may well be important in the chemistry that occurs in the gas phase of interstellar clouds. Using a new gas-grain chemical network with both gas-phase reactions and reactions on the surfaces of dust particles, we studied the role of OH–neutral reactions in dense interstellar clouds at 10, 50, and 100 K. We determined that at least one of these reactions can be significant, especially at the lowest temperatures studied, where the rate constants are large. It was found in particular that the reaction between CH3OH and OH provides an effective and unambiguous gas-phase route to the production of the gaseous methoxy radical (CH3O), which has been recently detected in cold, dense interstsellar clouds. The role of other reactions in this class is explored.

The 100 K structures of two salts, namely 2-amino-1H-benzimidazolium 3-phenylpropynoate, C7H8N3+·C9H5O2−, (I), and 2-amino-1H-benzimidazolium oct-2-ynoate, C7H8N3+·C8H11O2−, (II), both have monoclinic symmetry (space groupP21/c) and display N—H...O hydrogen bonding. Both structures show packing with corrugated sheets of hydrogen-bonded molecules lying parallel to the [001] direction. Two hydrogen-bonded ring motifs can be identified and described with graph setsR22(8) andR44(16), respectively, in both (I) and (II). Computational chemistry calculations performed on both compounds show that the hydrogen-bonded ion pairs are more energetically favourable in the crystal structure than their hydrogen–bonded neutral molecule counterparts.

The crystal structures of four phosphorus-containing polyoxamacrocycles 2,4, 6,11,13-Pentachloro-dibenzo[d,g][1,3,9,2]trioxaphosphacycloundecan-2-thione (1),2,4,9,14, 16-Pentachloro-dibenzo[g,j][1,3,6,12,2]tetraoxaphosphacyclotetra-decan-2-thione (2), 2,4, 10,16,18-Pentachloro-dibenzo[h,k][1,3,7,12,2]tetraoxa-phosphacyclohexadecan-2-thione (3) and 2,4,6,12,14,18,20,28,30—Nona-chloro-tetrabenzo[d,g,p,s] [1,3,9,13,15,21,2,14]hexaoxa diphosphacyclotetracosan-2,14-dithione (4) have been determined by X-ray diffraction. The result shows that compound 4 has a center of symmetry, and compounds 1, 2, and 3 have no elements of symmetry. The molecules of compounds 2 and 4 form inclusion complex with neutral molecule guest (CHCl3) which is outside of the phosphorus-containing macrocycle in the ratio of 1:1, and compounds 1 and 3 do not form inclusion complexes with CHCl3. The result obtained in this paper lays a foundation for further research on the complexing properties of phosphorus-containing polyoxamac...