Simple Molecular Structure Research Articles

Multiple crystal pathways and crystal polymorphs in protic ionic liquids

Multiple crystal pathways and crystal polymorphs were observed in protic ionic liquids (pILs), which are liquid or solid at room temperature. The pILs studied were methylammonium nitrate (MAN), dimethylammonium nitrate (DAN), ethylammonium nitrate (EAN), and propylammonium nitrate (PAN). MAN and DAN solidified as plastic crystals at room temperature, whereas EAN and PAN are liquids at room temperature. Solid MAN and DAN indicated crystal polymorphs. In spite of its simple molecular structure, complicated phase behaviors such as multiple crystal pathways and crystal polymorphs were observed in liquid EAN at low temperature [Abe et al., J. Mol. Liq. 241 (2017) 301]. Liquid PAN also possesses low-temperature anomalies in analogy with liquid EAN. Proton fluctuations, which disturb the crystal nucleation of liquid pILs at room temperature, cause multiple crystal pathways via a non-equilibrium state.

Structurally simple synthetic 1, 4-disubstituted piperidines with high selectivity for resistant Plasmodium falciparum

BackgroundEmergence of resistance to artemisinins and some of their combinations in chemotherapy of clinical malaria has intensified the search for novel safe efficacious antimalarial molecules. Fourteen synthetic 1, 4-disubstituted piperidines with simple molecular structures were evaluated in this study.MethodsAntiplasmodial activity were determined against cultured chloroquine-sensitive 3D7 and resistant Dd2 strains of P. falciparum by in vitro parasite growth inhibition. A primary screen was done to identify active compounds by fluorescence microscopy followed by a secondary screen to determine IC50 and IC90 values of active compounds by the parasite lactate dehydrogenase assay. Cytotoxicity of active compounds was assessed using the MTT/formazan assay and selectivity indices (SIs) determined. Optical densities were analysed to obtain experimental results.ResultsThe compounds produced 56 to 93% inhibition of parasite growth at 40 μg/mL. Eight compounds (2 ketone, 5 alcohol and one amine analogues) showed high activity (IC50s between 1 and 5 μg/mL). Nine compounds were highly selective for the parasite (SIs = 15 to 182). Three promising (alcohol) analogues were identified: [1-(4-fluorobenzyl) piperidin-4-yl] [4-fluorophenyl] methanol, (7), [1-(3, 4-dichlorobenzyl) piperidin-4-yl] [4- fluorophenyl] methanol (8) and [1-(4-bromobenzyl) piperidin-4-yl] [4- fluorophenyl] methanol (11) which were more active on the resistant strain (IC50 values between 1.03 to 2.52 μg/mL), than the sensitive strain (IC50 values between 2.51 to 4.43 μg/mL).ConclusionsThe alcohol analogues were the most active and most selective for the parasite with three promising hit molecules identified among them, suggesting the hydroxyl group at C-7’ in these alcohol analogues is contributing greatly to their antiplasmodial activity. Further exploration of the core structure using chemistry approaches and biological screening including in vivo studies in an animal model of malaria may yield important antimalarial leads.

Mechanofluorochromism of D-A typed phenothiazine derivative

A D-A typed phenothiazine derivative MPTPM has been designed and synthesized via a Friedel-Crafts reaction, which contains two benzoyl groups. It was found that MPTPM gave strong emission in solution and in solid state, and the solid fluorescence quantum yield was as high as 0.60. Moreover, an excellent reversible mechanofluorochromic behavior was realized upon the treatment of grinding/fuming with CH2Cl2 or heating in spite of a very simple molecular structure. The emission color of MPTPM changed from green to orange-yellow after grinding and could be restored via fuming with CH2Cl2 or heating with a spectra shift of ∼63 nm. Photophysical, XRD, DSC studies indicated the mechanofluorochromic properties of MPTPM originating from the transformation between crystalline phase and amorphous phase.

Umbelliferone as a Small Molecular Peroxidase Mimic towards Sensitive Detection of H2O2 and Glucose.

In this work, umbelliferone, a kind of coumarin derivative, was proved to exhibit peroxidase-like activity that could catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide to generate a blue-colored oxide (oxTMB). The catalytic mechanism is similar to that of native enzymes (e.g. horseradish peroxidase, HRP) and nanozymes, which follow the Michaelis-Menten kinetics behavior. Meanwhile, the 7-hydroxyl group of umbelliferone plays a significant role in the peroxidase-like activity. Compared with enzymes and nanozymes, this small molecular mimic enzyme possesses the advantages of low cost, simple molecular structures, small molecular weight and high stability against harsh conditions. Based on the favorable peroxidase mimetic activity of umbelliferone, a convenient, practical and sensitive H2O2 and glucose detection method was successfully established. This work not only opens some new inspirations into seeking for novel molecular enzyme mimetics with excellent catalytic activities, but also provides promising assays for clinical diagnosis.

Logical operations using phenyl ring

Exploiting the effects of quantum interference we put forward an idea of designing three primary logic gates, OR, AND and NOT, using a benzene molecule. Under a specific molecule-lead interface geometry, anti-resonant states appear which play the crucial role for AND and NOT operations, while for OR gate no such states are required. Our analysis leads to a possibility of designing logic gates using simple molecular structure which might be significant in the area of molecular electronics.

New atomistic model of pyrrole with improved liquid state properties and structure

AbstractStructural characterization of liquid pyrrole has been obtained by performing classical molecular dynamics simulations with a new parameterization of electrostatic interactions. Despite the relatively simple molecular structure of pyrrole, a correct and accurate representation of its intermolecular interactions in bulk phase is a challenging task, since these are affected at short range by the quadrupole–quadrupole term. This new parameterization permits not only to correctly describe the liquid structure but also to obtain macroscopic properties in excellent agreement with experiments.

Reduced interface losses in inverted perovskite solar cells by using a simple dual-functional phenanthroline derivative

Interface losses at metal/organic interface is a critical issue in organic electronic devices. The interfacial layers play a significant role in enhancing the device performance and the interfacial material design criteria are ongoing challenges to be faced in optimization the device performance. In this work, a simple Phenanthroline derivative Phen-I was synthesized through a quaternization reaction in a high yield without complicated purification process. Besides its good wettability and compatibility of the contact between metal electrode and organic layer, interestingly, Phen-I displays a dual functional property, i.e., it not only lowers the work function of the metallic cathode to increase electron extraction but also can be doped into electron transporting material to enhance the conductivity. The inverted perovskite solar cells (PSCs) with Phen-I as cathode interlayer (CIL) show superior performance both in power conversion efficiency, with a maximum PCE of 18.13%, and devices stability as compared with the control devices. Encouragingly, the best PCE of 19.27% was obtained when the perovskite layer based on FA0.3MA0.7PbI2.7Cl0.3 perovskite system. Meanwhile, the devices with Phen-I as CIL show low J-V hysteresis during the forward and reverse bias sweeping. Subsequent studies demonstrate that the performance of the inverted PSCs also improves to 15.25% using 5% Phen-I:PC61BM as electron transporting layer (ETL). Herein, the interface between the metal electrode and ETL is carefully investigated using a series of electrical and surface potential techniques. These results demonstrate that Phen-I is a dual-functional interlayer material to reduce interface losses, which, highlights the broad promise of this new class of materials for applications in organic electronic devices. Meanwhile, owing to the simple molecular structure, low-cost and solution processible, these intriguing features render Phen-I more suitable for efficient organic electronics in large area printing process.

Thiophene-Based Organic Semiconductors.

Thiophene-based π-conjugated organic small molecules and polymers are the research subject of significant current interest owing to their potential use as organic semiconductors in material chemistry. Despite simple and similar molecular structures, the hitherto reported properties of thiophene-based organic semiconductors are rather diverse. Design of high performance organic semiconducting materials requires a thorough understanding of inter- and intra-molecular interactions, solid-state packing, and the influence of both factors on the charge carrier transport. In this chapter, thiophene-based organic semiconductors, which are classified in terms of their chemical structures and their structure-property relationships, are addressed for the potential applications as organic photovoltaics (OPVs), organic field-effect transistors (OFETs) and organic light emitting diodes (OLEDs).

Structurally Simple and Easily Accessible Perylenes for Dye-Sensitized Solar Cells Applicable to Both 1 Sun and Dim-Light Environments.

The need for low-cost and highly efficient dyes for dye-sensitized solar cells under both the sunlight and dim light environments is growing. We have devised GJ-series push-pull organic dyes which require only four synthesis steps. These dyes feature a linear molecular structure of donor-perylene-ethynylene-arylcarboxylic acid, where donor represents N,N-diarylamino group and arylcarboxylic groups represent benzoic, thienocarboxylic, 2-cyano-3-phenylacrylic, 2-cyano-3-thienoacrylic, and 4-benzo[c][1,2,5]thiadiazol-4-yl-benzoic groups. In this study, we demonstrated that a dye without tedious and time-consuming synthesis efforts can perform efficiently. Under the illumination of AM1.5G simulated sunlight, the benzothiadiazole-benzoic-containing GJ-BP dye shows the best power conversion efficiency (PCE) of 6.16% with VOC of 0.70 V and JSC of 11.88 mA cm-2 using liquid iodide-based electrolyte. It also shows high performance in converting light of 6000 lx light intensity, that is, incident power of ca. 1.75 mW cm-2, to power output of 0.28 mW cm-2 which equals a PCE of 15.79%. Interestingly, the benzoic-containing dye GJ-P with a simple molecular structure has comparable performance in generating power output of 0.26 mW cm-2 (PCE of 15.01%) under the same condition and is potentially viable toward future application.

Palmitoylated amino acids as low-molecular-weight gelators for ionic liquids

We report palmitoylated amino acids (glycine, l-valine, l-isoleucine, l-aspartic acid, l-glutamic acid, l-methionine, l-phenylalanine, l-lysine) as low-molecular-weight gelators for ionic liquids (ILs). The palmitoylated amino acids gelate ammonium- and imidazolium-based ILs, at gelation concentrations of 0.3–1.6 wt.%, despite their simple molecular structures. Eight types of gelators are synthesized, with palmitoylated methionine (Pal-Met) and palmitoylated phenylalanine (Pal-Phe) exhibiting high gelation ability toward the tested ILs. Scanning electron microscopy and confocal laser scanning microscopy observations suggest that the gelator molecules self-assemble into nanofibers within the ILs, which leads to gelation. The ionogels exhibit reversible thermal transition and viscoelastic properties, which are typical of gels. Fourier-transform infrared spectra recorded at various temperatures reveal that hydrogen bonding and van der Waals interactions between gelator molecules are important in the self-assembly. Incorporating gelators of varying concentrations do not affect the intrinsic conductivities of the ILs.

Lagrangian Mesh Model with Regridding for Planar Poiseuille Flow

AbstractMany biological settings involve complex fluids that have non-Newtonian mechanical responses that arise from suspended microstructures. In contrast, Newtonian fluids are liquids or mixtures of a simple molecular structure that exhibit a linear relationship between the shear stress and the rate of deformation. In modeling complex fluids, the extra stress from the non-Newtonian contribution must be included in the governing equations.In this study we compare Lagrangian mesh and Oldroyd-B formulations of fluid-structure interaction in an immersed boundary framework. The start-up phase of planar Poiseuille flow between two parallel plates is used as a test case for the fluid models. For Newtonian and Oldroyd-B fluids there exist analytical solutions which are used in the comparison of simulation and theoretical results. The Lagrangian mesh results are compared with Oldroyd-B using comparable parameters. A regridding algorithm is introduced for the Lagrangian mesh model. We show that the Lagrangian mesh model simulations with regridding produce results in close agreement with the Oldfoyd-B model.

Phase‐Transition and Photoluminescence Properties of a Hybrid Layered Perovskite: Bis[(cyclohexylmethyl)ammonium] Tetrabromidolead(II)

In addition to the appealing semiconducting properties displayed by layered SnII or PbII halidometallates, intriguing phase‐transition‐induced properties, such as dielectric and ferroelectric properties, have recently been found by us in (benzylammonium)2PbCl4 and (cyclohexylammonium)2PbBr4–4xI4x (x = 0–1). The simple molecular structures of the layered compounds allow further chemical design for the modification of the physical properties. Thus, we extended the study to layered compounds templated by structurally similar organic cations to achieve future functions. Here, we report the design of a layered perovskite templated by cyclohexylmethylammonium cations, namely, bis[(cyclohexylmethyl)ammonium] tetrabromidolead(II). We found that this compound exhibits not only photoluminescence with a remarkably high efficiency (quantum yield = 21 %) but also interesting phase‐transition‐related physical properties, such as striking dielectric responses. These results reveal the great application potential of organic–inorganic hybrid compounds in the field of phase‐transition multifunctional materials. More interesting phase‐transition crystals are expected to be tailored in the future by taking advantage of the richness of layered perovskites.

Exploring the Multifunctionality of a Novel Long-Chain Amidoamine Amphiphile.

In this review, we demonstrate that the practical applications of a novel long-chain amidoamine derivative with a simple molecular structure (C18AA) are equivalent to or higher in number than those of supramolecules with complex molecular structures. Molecular assemblies of C18AA exhibit distinctive thermal responsiveness; namely, C18AA can form a gel with apolar organic solvents, while O/W emulsions of C18AA act as a heat-induced gelator that undergoes a phase transition from solution to gel upon heating. We also show that C18AA emulsions containing a quaternary ammonium salt develop an iridescent color over a specific temperature range. Further, molecular assemblies of C18AA serve as high-performance soft templates for the preparation of shape-controlled metal nanocrystals such as ultrathin Au nanowires and Pd nanowires.

Molecular Characterization of Mitochondrial D Loop of Indian Red Jungle Fowl

Mitochondrial DNA has the characteristic of quick evolution, matrilineal inheritance, and simple molecular structure, and it serves as the most used marker for molecular study. As an important role of genomics, studying it can help understand the origins, history, and adaptation of domestication. A 1325 bp fragment of the mtDNA D-loop region was amplified, sequenced and phylogenetic study was done. Out of 400 sites about 12 % were polymorphic between the Gallus gallus (G.g.) subspecies and most of them (60%) were transitions. Indian RJF showed very low genetic distances (0.008-0.013) with G.g. gallus birds from Thailand as compared to those from Japan and Indonesia. The G.g. murghi showed comparatively high genetic distance i.e. 031-0.034 with G.g. spadiceus and from 0.061-0.066 with G. gallus bankiva. The phylogenetic tree showed that G.g. banikva is well separated from the other three subspecies as it made a separate cluster. G.g. gallus makes two separate clusters i.e. one those from Thailand and other those from Japan and Indonesia. Within each chicken breed, there is an excess of homozygosity, but there is no significant reduction in the nucleotide diversity. Phenotypic modifications of chicken breeds as a result of artificial selection appear to stem from ancestral polymorphisms at a limited number of genetic loci.

Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory.

A simple molecular structure of ortho-derived perylene diimide diploid for non-fullerene organic solar cells with efficiency over 8%

A simple molecular structure of ortho-derived perylene diimides (PDI) diploid has been developed for non-fullerene organic solar cells (OSCs) with a high power conversion efficiency (PCE) of 8.3%, indicating that such a concise molecular structure with a high PCE has great potential for the practical applications in OSCs.

The hydrogen-bond collective dynamics in liquid methanol.

The relatively simple molecular structure of hydrogen-bonded (HB) systems is often belied by their exceptionally complex thermodynamic and microscopic behaviour. For this reason, after a thorough experimental, computational and theoretical scrutiny, the dynamics of molecules in HB systems still eludes a comprehensive understanding. Aiming at shedding some insight into this topic, we jointly used neutron Brillouin scattering and molecular dynamics simulations to probe the dynamics of a prototypical hydrogen-bonded alcohol, liquid methanol. The comparison with the most thoroughly investigated HB system, liquid water, pinpoints common behaviours of their THz microscopic dynamics, thereby providing additional information on the role of HB dynamics in these two systems. This study demonstrates that the dynamic behaviour of methanol is much richer than what so far known, and prompts us to establish striking analogies with the features of liquid and supercooled water. In particular, based on the strong differences between the structural properties of the two systems, our results suggest that the assignment of some dynamical properties to the tetrahedral character of water structure should be questioned. We finally highlight the similarities between the characteristic decay times of the time correlation function, as obtained from our data and the mean lifetime of hydrogen bond known in literature.

Synthesis of high-soluble and non-fluorescent perylene derivatives and their effect on the contrast ratio of LCD color filters

We designed and synthesized perylene-based dyes for dye-based LCD color filters that highly soluble in organic industrial solvents, exhibit very weak fluorescence, and can be easily synthesized due to their simple molecular structures. The synthesized dyes were designed containing methoxy groups in the terminal-, bay-, or both positions for developing fluorescence quenched dyes. And, dyes with strong fluorescence and similar molecular structures to the fluorescence quenched dyes were also synthesized to clearly compare and analyze the effect of fluorescence on the optical properties. Finally, we fabricated dye-based color filters using the synthesized dyes and analyzed the optical performances of the color filters. The methoxy group in the bay-substituents has an enormous effect on the fluorescence quenching without the conspicuous influences on molecular behavior or dye aggregation. And, the fluorescence quenched dyes have remarkable effects in minimizing the increment of minimum brightness and prohibiting the contrast ratio decrease.

Characterization of Dissolved Organic Matter in Lake Baiyangdian Using Spectroscopic Techniques and Multivariate Statistical Analysis

Dissolved organic matter (DOM) collected from the surface and overlying waters in different functional regions in Lake Baiyangdian were analyzed by spectroscopic techniques combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA), to interpret water quality, and sources of pollutants. The results showed that the deterioration of water quality has intensified at river estuary and aquaculture area. Meanwhile, these regions dominated by plants had relatively low dissolved oxygen concentrations. UV‐vis spectra showed lower humification degree and simpler molecular structure in the DOM collected from the pollutant‐receiving region. The analysis of PCA combined with synchronous fluorescence spectra yielded two principal components (PCs) that account for 99.44% of the variance. PC1 showed a dominant protein‐like fluorophore at 279 nm and PC2 was characterized by dominated fulvic‐like fluorophores (325 and 331 nm). The results of PCA indicated that DOM collected from the river estuary, the aquaculture region, and the eutrophication area exhibited a higher protein‐like fluorophore, and higher PC1 and lower PC2 loadings (PC1 > 0.7, PC2 < 0.4). Meanwhile, a higher fulvic‐like fluorophore existed in the DOM samples collected from a clean region (PC1 < 0.4, PC2 > 0.7). HCA identified four clusters that accorded with the PCA results. This study suggested that water quality and the sources, and spectral characteristics of DOM were influenced mainly by human activities (agriculture, industrial, and domestic wastewater from upstream, food and excrement from aquaculture) and natural processes (aquatic‐plant and microorganism activities).

Thymoquinone: An edible redox-active quinone for the pharmacotherapy of neurodegenerative conditions and glial brain tumors. A short review.

There exist few efficient agents in the neurological and neurosurgical armamentarium for treatment of neurotrauma, refractory seizures and high grade glial tumors. Pathophysiological conditions of diverse neural injuries have converging common pathways including oxidative stress and apoptosis. Targeted therapies have been throughly investigated, but limited success has been achieved until now. Phytochemical drugs may provide easily achievable and cheap adjunctive sources. Thymoquinone is an edible quinone obtained from Nigella sativa seed oil and exerts powerful antiinflammatory, antioxidant and antitumor activities in experimental models. Recently emerging studies conducted with animal models suggest that thymoquinone - bearing a very simple molecular structure - significantly crosses the blood brain barrier and exerts neuromodulatory activities. Indeed, in animal studies, the following actions of thymoquinone were demonstrated: 1-Protection against ischemic brain damage. 2-Reduction of epileptic seizures and associated cerebral oxidative injury. 3-Reduction of morphine tolerance and associated oxidative brain damage. 4-Anxiolytic effects and reduction of immobility stress-associated cerebral oxidative injury. 5-Reduction of diabetes-induced cerebral oxidative stress, 6-Reduction of cerebral oxidative injuries induced by noxious exposures including toluene, lead and ionizing radiation. Substantial in vitro data suggest that thymoquinone may be beneficial in treatment of glial tumors. However, there is no clinical study investigating its antitumor effects. In fact, thymoquinone suppresses growth and invasion, and induces apoptosis of glial tumor cells via degrading tubulins and inhibiting 20S proteasome, telomerase, autophagy, FAK and metalloproteinases. A simple and easily available agent may be a promising adjunctive treatment option in neurological and neurosurgical practice.