Spontaneous Curvature Induction in an Artificial Bilayer Membrane.

Maintaining lipid asymmetry across membrane leaflets is critical for functions like vesicular traffic and organelle homeostasis. However, a lack of molecular-level understanding of the mechanisms underlying membrane fission and fusion processes in synthetic systems precludes their development as artificial analogs. Here, we report asymmetry induction of a bilayer membrane formed by an extended π-conjugated molecule with oxyalkylene side chains bearing terminal tertiary amine moieties (BA1) in water. Autogenous protonation of the tertiary amines in the periphery of the bilayer by water induces anisotropic curvature, resulting in membrane fission to form vesicles and can be monitored using time-dependent spectroscopy and microscopy. Interestingly, upon loss of the induced asymmetry by extensive protonation using an organic acid restored bilayer membrane. The mechanism leading to the compositional asymmetry in the leaflet and curvature induction in the membrane is validated by density functional theory (DFT) calculations. Studies extended to control molecules having changes in hydrophilic (BA2) and hydrophobic (BA3) segments provide insight into the delicate nature of molecular scale interactions in the dynamic transformation of supramolecular structures. The synergic effect of hydrophobic interaction and the hydrated state of BA1 aggregates provide dynamicity and unusual stability. Our study unveils mechanistic insight into the dynamic transformation of bilayer membranes into vesicles.

Tuning the Electronic and Optical Properties of Phenoxaborin Based Thermally Activated Delayed Fluorescent Materials: A DFT Study.

The electronic and optoelectronic properties of molecules constituted by benzene as linker, phenoxaborin as acceptor coupled with different types of donor moieties are investigated using the density functional theoretical method. The energy gap between the first excited singlet and triplet states (ΔEST) of the designed molecules (1-9) is found to be less than 0.5 eV suggesting them as ideal candidates for thermally activated delayed fluorescence (TADF) emitters. The analysis of frontier molecular orbitals of the molecules revealed a minimum spatial overlap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in favor of the small values of ΔEST. Among the molecules studied, the one in which dihydrophenazine acts as the donor has the lowest value of ΔEST. All designed molecules are good electron transporters. The non-linear optical properties of the molecules are also examined.

Tuning of the Singlet-Triplet Energy Gap of Donor-Linker-Acceptor Based Thermally Activated Delayed Fluorescent Emitters.

Thermally activated delayed fluorescent emitters based on carbazole donor, benzonitrile acceptor with the linkers biphenyl, bipyridine and naphthalene are investigated using the density functional theoretical method. The molecule in which bipyridine acts as the linker with the least ΔEST is further selected for the designing of a series of D-L-A framework TADF molecules. Remarkably, the ΔEST is decreased successively by attaching the additional cyano groups at the acceptor site which is further reduced when the electron donating methoxy groups are attached at the donor site. To know the effect of substituents on ΔEST, the acceptor moiety of the D-L-A framework is modified with -F, -Cl and -CF3 substituents. The studies showed a relatively less decrement in the value of ΔEST compared to the cyano substituted molecules. However, ΔEST significantly reduced further on attaching methoxy groups at the donor site.

Probing the Interaction of NO with C60: Comparison between Endohedral and Exohedral Complexes.

Recent advances in synthetic methodologies have opened new strategies for synthesizing stable metal-free electron spin systems based on fullerenes. Introducing nitric oxide (NO) inside a fullerene cage is one of the methods to attain this goal. In the present study, dispersion corrected density functional theory (B3LYP-D3) has been used to evaluate the structure, stability, and electronic properties of NO encapsulated fullerene NO@C60 and compared those with its exohedral fullerene NO.C60 analog. The calculated stabilization energy for NO@C60 is appreciably higher than NO.C60, and this difference is comprehended via the Quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) topological analyses. The delocalization of electron density of NO and the C60 cage in NO@C60 is discussed using electrostatic potential analysis. In addition, an attempt has been made to understand the different locations and orientations involving the interaction of two NO radicals and the fullerene C60. It is shown that the encapsulation of the NO dimer inside the C60 cage is an energetically unfavorable process. On the other hand, stable structures are obtained upon the physisorption of other NO on the surface of NO@C60 and NO.C60. The present work provides an in-depth understanding of the interaction of NO and C60 fullerene, its preferable position, and its orientation in both endohedral and exohedral complexes.

Switching the charge transfer characteristics of quaterthiophene from p-type to n-type via interactions with carbon nanotubes.

Carbon nanotube-based semiconductors are of great interest for optoelectronic applications at the nanoscale. The present study investigates the structural, optoelectronic and charge transport properties of non-covalent complexes formed between carbon nanotubes (CNTs) and quaterthiophene (4T) by employing dispersion-corrected density functional methods. The effect of different functionals viz., B97-D, B3LYP-GD3 and ωB97X-D on the properties of endo- and exohedral complexes is examined. The endohedral complex (4T@CNT) is found to be energetically more stable than the exohedral one (4T-CNT). Electronic properties such as the ionization energy, electron affinity and energy gap between the frontier molecular orbitals of the CNT are not significantly changed by the adsorption or the encapsulation of 4T. Contrary to the p-type characteristics of 4T, its complexes formed with CNTs exhibit n-type characteristics due to the higher electron mobility than the hole mobility. Among the endo- and exohedral complexes, the former one shows the highest electron mobility of 3.79 cm2 V-1 s-1. The absorption properties of all the systems were studied by time-dependent density functional theory (TD-DFT). It is found that the complexes undergo several charge transfer transitions in the visible region of the electromagnetic spectrum. The above results unequivocally suggest that the charge-transfer characteristics of 4T can be altered on forming complexes with CNTs.

A multifunctional triazine-based nanoporous polymer as a versatile organocatalyst for CO2 utilization and C-C bond formation.

A triazine-based nanoporous multifunctional polymer with a SABET of 304 m2 g-1 has shown versatile catalytic activity in the conversion of CO2 to cyclic carbonates at 4 bar with almost 100% yield and selectivity, and in the conversion of CO2 to methanol and methane electrochemically. Additionally, it also catalyzes C-C bond formation via the Knoevenagel reaction.

Nitrogen Amelioration-Driven Carbon Dioxide Capture by Nanoporous Polytriazine.

Nitrogen-enriched nanoporous polytriazines (NENPs) have been synthesized by ultrafast microwave-assisted condensation of melamine and cyanuric chloride. The experimental conditions have been optimized to tune the textural properties by synthesizing materials at different times, temperatures, microwave powers, and solvent contents. The maximum specific surface area (SABET) of 840 m2 g-1 was estimated in the sample (NENP-1) synthesized at 140 °C with a microwave power of 400 W and reaction time of 30 min. One of the major objectives of achieving a large nitrogen content as high as 52 wt % in the framework was realized. As predicted, the nitrogen amelioration has benefitted the application by capturing a very good amount of CO2 of 22.9 wt % at 273 K and 1 bar. Moreover, the CO2 storage capacity per unit specific surface area (per m2 g-1) is highest among the reported nanoporous organic frameworks. The interaction of the CO2 molecules with the polytriazine framework was theoretically investigated by using density functional theory. The experimental CO2 capture capacity was validated from the outcome of the theoretical calculations. The superior CO2 capture capability along with the theoretical investigation not only makes the nanoporous NENPs superior adsorbents for the energy and environmental applications but also provides a significant insight into the fundamental understanding of the interaction of CO2 molecules with the amine functionalities of the nanoporous frameworks.

Spin density transfer from guest to host in endohedral heterofullerene dimers.

The endohedral heterofullerenes (B@C59B)2, (B@C59N)2, (N@C59B)2 and (B@C59N-N@C59B) are investigated using dispersion corrected density functional theory. Several spin states of these complexes are considered and their stable spin states are reported. For 1[(B@C59B)2] and 1[(B@C59N-N@C59B)], the encapsulated atoms are positioned near the surface of the host cages, in contrast to other spin states where they are positioned at the centre of the cages. In complexes 1[(B@C59N)2], 3[(B@C59N)2] and 7[(N@C59B)2], the guest atoms are found to be at the centre of the host cages. The spin polarization and the transfer of spin density between the components of the complexes for different stable spin states are analyzed. Based on the spin states of the complexes, the spin-spin interaction is found to be either ferromagnetic or anti-ferromagnetic. Unlike other complexes, in 1[(B@C59B)2] and 1[(B@C59N-N@C59B)] the spin density is transferred from the guest to the host followed by anti-ferromagnetic coupling between the monomers. The thermodynamic feasibility of formation of the complexes is also examined. The electron affinity, ionization potential and dipole moment of the above systems are determined. The singlet state of the heterodimer (B@C59N-N@C59B) showed high polarity due to the slight rotation along the dihedral angle φNCCB.

Practical consensus recommendations for gestational breast cancer.

This manuscript provides a practical and easy to use consensus recommendation to community oncologists on how to manage gestational breast cancer.

Structural, optoelectronic and charge transport properties of the complexes of indigo encapsulated in carbon nanotubes.

Using the dispersion-corrected density functional B97D and 6-31g(d,p) basis set, the structural, stability, electronic, optical and charge transport properties of the complexes formed by encapsulating indigo inside carbon nanotubes (CNTs) of varying diameters are investigated. Based on the stabilization energy of the complexes indigo@(n,n)CNT (where n = 6, 7 and 8), indigo@(7,7)CNT is shown to be the most stable owing to the ideal diameter of (7,7)CNT for encapsulating indigo. The nature of the interaction between the guest and the host is investigated by means of energy decomposition analysis employing the symmetry adapted perturbation theory. Electronic properties such as the ionization energy, the electron affinity and the energy gap between the highest occupied and lowest unoccupied molecular orbitals (ΔEH-L) of the complexes are determined. The low values of ΔEH-L (<1 eV) for the complexes suggest that they can act as narrow energy gap semiconductors. All the complexes exhibit high hole and electron mobilities which vary inversely with respect to the diameter of the CNT. Using the time-dependent density functional theoretical method, the absorption properties are predicted for the most stable complex indigo@(7,7)CNT. The presence of charge transfer peaks in the visible and near-infrared regions of the electromagnetic spectrum suggests that the complexes are suitable for optoelectronic devices such as solar cells.

Formation of a nanobubble and its effect on the structural ordering of water in a CH4-N2-CO2-H2O mixture.

The replacement of methane (CH4) from its hydrate by a mixture of nitrogen (N2) and carbon dioxide (CO2) involves the dissociation of methane hydrate leading to the formation of a CH4-N2-CO2-H2O mixture that can significantly influence the subsequent steps of the replacement process. In the present work, we study the evolution of dissolved gas molecules in this mixture by applying classical molecular dynamics simulations. Our study shows that a higher CO2 : N2 ratio in the mixture enhances the formation of nanobubbles composed of N2, CH4 and CO2 molecules. To understand how the CO2 : N2 ratio affects nanobubble nucleation, the distribution of molecules in the bubble formed is examined. It is observed that unlike N2 and CH4, the density of CO2 in the bubble reaches a maximum at the surface of the bubble. The accumulation of CO2 molecules at the surface makes the bubble more stable by decreasing the excess pressure inside the bubble as well as surface tension at its interface with water. It is found that a frequent exchange of gas molecules takes place between the bubble and the surrounding liquid and an increase in concentration of CO2 in the mixture leads to a decrease in the number of such exchanges. The effect of nanobubbles on the structural ordering of water molecules is examined by determining the number of water rings formed per unit volume in the mixture. The role of nanobubbles in water structuring is correlated to the dynamic nature of the bubble arising from the exchange of gas molecules between the bubble and the liquid.

Needs of exploring the burden of recent onset seizures due to neurocysticercosis and challenges in southeast Asia focusing on scenario in Malaysia.

Seizures due to neurocysticercosis (NCC) is a neglected human-to-human transmitted disorder and an emerging problem worldwide. A substantial portion of recent onset seizures is known to be attributed to NCC in Taenia solium (T. solium) endemic areas where populations which neither raise pigs nor eat pig meat are also at risk. High prevalence of NCC causing epilepsy has been reported in the underdeveloped areas of Southeast Asia (SEA) however, only fragmentary information on its incidence is available in countries like Malaysia. In Malaysia T. solium infection was previously thought to be infrequent due to Muslim population majority and the religious prohibition of consuming pork, but it is not totally absent. There is an evident lack of knowledge and awareness of the actual burden, routes of transmission, and the impact of NCC in this region. The problem is assumed to be more prevalent particularly in cities because of the frequent inflow of possibly T. solium infected individuals or carriers among those who migrate from neighboring endemic countries to Malaysia. The issue of imported cases that are likely to be emerging in Malaysia is highlighted here. An accurate quantification of regional burdens of epilepsy due to NCC in Malaysia is warranted considering the disease emergence in its neighboring countries. It is suggested that the importance of NCC be recognized through quantification of its burden, and also to collect epidemiological data for its subsequent elimination in line of World Health Organization's mission for control of cysticercosis as a neglected tropical disease. In this review the need as well as a strategy for neuro-care center screening of epilepsy cases, and various issues with possible explanations are discussed. It is also proposed that NCC be declared as a reportable disease which is one of the eradicable public health problems in SEA.

Structure, Stability, and Properties of Boron Encapsulated Complexes of C60, C59B, and C59N.

Density functional studies are performed for the boron atom encapsulated complexes of C60, C59B, and C59N using B3LYP and B3LYP-GD2 functionals with 6-311G* basis set. The study shows that the complexes B@C59B and B@C59N can exist in different forms which differ in their structure as well as electronic and magnetic properties. The nature of interaction between the guest and the host is analyzed based on the stabilization energies of complexes for their different spin states. The electronic properties such as vertical electron affinity (VEA), vertical ionization energy (VIE), and energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the complexes are calculated. The transfer of electron spin density and spin-spin coupling of electrons between the guest and the host are examined. The study reveals that ferromagnetic core@shell spin coupling occurs between the host and the guest species of the complexes B@C59B and B@C59N in their triplet state without any transfer of spin density. The values of hyperfine coupling constant (hfcc) for the heteroatom of the cage and for the encapsulated boron atom of the complexes are analyzed, and it indicates that the value of hfcc for the encapsulated boron decreases significantly due to confinement.

Self-Assembling and Luminescent Properties of Chiral Bisoxadiazole Derivatives in Solution and Liquid-Crystalline Phases.

Herein, we report the synthesis, self-assembly, and electroluminescence characteristics of a new green-emitting, pseudodiscoid chiral molecule, OXDC, containing an electron-donating stilbene core and an electron-accepting oxadiazole substituent. The helical organization and specific interaction of the chiral pseudodiscoid molecule resulted in the formation of self-assembled nanofibers with a columnar superstructure. Macroscopic chirality was observed in both the liquid-crystalline phases and the self-assembled nanofibers of OXDC, a feature which was absent in the analogous achiral oxadiazole derivative reported earlier [ Sivadas , A. P. ; Supergelation via Purely Aromatic π-π Driven Self-Assembly of Pseudodiscotic Oxadiazole Mesogens . J. Am. Chem. Soc. 2014 , 136 , 5416 - 5423 ]. A high-performance organic light-emitting device was demonstrated using OXDC as the emitting material, with a luminous intensity of 10 115 cd m-2 at 5 V and chromaticity coordinates of (0.32, 0.51).

Natural Gas Evolution in a Gas Hydrate Melt: Effect of Thermodynamic Hydrate Inhibitors.

Natural gas extraction from gas hydrate sediments by injection of hydrate inhibitors involves the decomposition of hydrates. The evolution of dissolved gas from the hydrate melt is an important step in the extraction process. Using classical molecular dynamics simulations, we study the evolution of dissolved methane from its hydrate melt in the presence of two thermodynamic hydrate inhibitors, NaCl and CH3OH. An increase in the concentration of hydrate inhibitors is found to promote the nucleation of methane nanobubbles in the hydrate melt. Whereas NaCl promotes bubble formation by enhancing the hydrophobic interaction between aqueous CH4 molecules, CH3OH molecules assist bubble formation by stabilizing CH4 bubble nuclei formed in the solution. The CH3OH molecules accumulate around the nuclei leading to a decrease in the surface tension at their interface with water. The nanobubbles formed are found to be highly dynamic with frequent exchange of CH4 molecules between the bubble and the surrounding liquid. A quantitative analysis of the dynamic behavior of the bubble is performed by introducing a unit step function whose value depends on the location of CH4 molecules with respect to the bubble. It is observed that an increase in the concentration of thermodynamic hydrate inhibitors reduces the exchange process, making the bubble less dynamic. It is also found that for a given concentration of the inhibitor, larger bubbles are less dynamic compared to smaller ones. The dependence of the dynamic nature of nanobubbles on bubble size and inhibitor concentration is correlated with the solubility of CH4 and the Laplace pressure within the bubble. The effect of CO2 on the formation of nanobubble in the CH4-CO2 mixed gas hydrate melt in the presence of inhibitors is also examined. The simulations show that the presence of CO2 molecules significantly reduces the induction time for methane nanobubble nucleation. The role of CO2 in the early nucleation of bubble is explained based on the interaction between the bubble and the dissolved CO2 molecules.

Spin-Spin Coupling in Nitrogen Atom Encapsulated C60, C59N, and Their Respective Dimers.

Density functional theoretical calculations were performed to study the stability and magnetic properties of nitrogen-encapsulated C60, C59N, and their respective dimers at B3LYP/6-311G* and B3LYP-GD2/6-311G* levels of theory. For the most stable spin state of each of the above complexes, spin density transfer and spin-spin coupling between different components are investigated. The nature of bonding between the guest and the host is analyzed based on the highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap and the respective molecular orbital diagrams. The analysis of spin density showed that the encapsulated nitrogen retained its atomic state in N@C60 and N@C59N. Depending on the multiplicity of N@C59N, the unpaired electrons of the encapsulated nitrogen are coupled with those of the cage anti-ferromagnetically or ferromagnetically. The present study also showed that the complex (N@C60)2 can exist in two isoenergetic spin states, namely, (7)[(N@C60)2] and (1)[(N@C60)2]. In the former, the encapsulated nitrogens are ferromagnetically coupled, whereas they are coupled anti-ferromagnetically in the latter. A similar coupling between the guest species occurs in the nitrogen analogues (7)[(N@C59N)2] and (1)[(N@C59N)2]. The stabilization energy of the endohedral nitrogen complexes indicated that the interaction between the guest and the host cage is purely noncovalent.

Charge transport and optical properties of the complexes of indigo wrapped over carbon nanotubes.

A new molecular system comprising the non-covalently functionalized complexes of single walled (6,6) carbon nanotubes (SWCNTs) of finite length with indigo is proposed based on the dispersion-corrected density functional theory calculations. In the complexes viz. the dyad and triad, indigo is wrapped over carbon nanotubes in the ratio of 1 : 1 and 2 : 1, respectively. A comprehensive study of stabilization energy, ionization energy, electron affinity, the energy gap between the highest occupied and lowest unoccupied molecular orbitals (ΔELUMO-HOMO), and absorption spectra unravels the structure-property relationship of the complexes. The energy gap of ∼1 eV between the HOMO and the LUMO of the complexes suggests that they can be semiconductive. The energy levels of the frontier molecular orbitals of indigo and CNT suggest the possibility of the photoinduced charge transfer between them. Using the charge hopping rate based on Marcus theory, a hole mobility as high as 8.77 cm(2) V(-1) s(-1) is obtained for the dyad. For both the dyad and triad, a higher value of hole mobility than electron mobility is observed, thereby suggesting them to be useful for p-type semiconductor devices. The time-dependent density functional theory (TD-DFT) calculations predict that the absorption of indigo-CNT complexes occurs in the visible and the near-infrared regions finding applications in organic light emitting diodes (OLEDs). Furthermore, the effects of the length and the capping of CNTs as well as the orientation of indigo over the CNTs on the charge transport properties are also discussed.

Carbon dioxide induced bubble formation in a CH4-CO2-H2O ternary system: a molecular dynamics simulation study.

The extraction of methane from its hydrates using carbon dioxide involves the decomposition of the hydrate resulting in a CH4-CO2-H2O ternary solution. Using classical molecular dynamics simulations, we investigate the evolution of dissolved gas molecules in the ternary system at different concentrations of CO2. Various compositions considered in the present study resemble the solution formed during the decomposition of methane hydrates at the initial stages of the extraction process. We find that the presence of CO2 aids the formation of CH4 bubbles by causing its early nucleation. Elucidation of the composition of the bubble revealed that in ternary solutions with high concentration of CO2, mixed gas bubbles composed of CO2 and CH4 are formed. To understand the role of CO2 in the nucleation of CH4 bubbles, the structure of the bubble formed was analyzed, which revealed that there is an accumulation of CO2 at the interface of the bubble and the surrounding water. The aggregation of CO2 at the bubble-water interface occurs predominantly when the concentration of CO2 is high. Radial distribution function for the CH4-CO2 pair indicates that there is an increasingly favorable direct contact between dissolved CH4 and CO2 molecules in the bubble-water interface. It is also observed that the presence of CO2 at the interface results in the decrease in surface tension. Thus, CO2 leads to greater stability of the bubble-water interface thereby bringing down the critical size of the bubble nuclei. The results suggest that a rise in concentration of CO2 helps in the removal of dissolved CH4 thereby preventing the accumulation of methane in the liquid phase. Thus, the presence of CO2 is predicted to assist the decomposition of methane hydrates in the initial stages of the replacement process.

Structure and properties of small aurocarbons: a selective study.

Gold clusters are versatile catalysts, and adding nonmetal dopants can allow tuning of their electronic properties via both shape and composition alteration. In the present work, mixed clusters of carbon and gold atoms are studied in terms of structure, stability, and the correlation between the shape and electronic properties by using a density functional theory approach. Four series of isomers (hydrocarbon analogues, carbon chains and cycles on gold surface, and carbon cores encapsulated by gold atoms) are investigated, exhibiting variation of the relative stability with the system size. Calculated vertical ionization energies, vertical electron affinities, and HOMO-LUMO energy gaps of the mixed clusters show a considerable change relative to the values for the pure gold clusters, the properties generally altering more strongly for the gold-encapsulated-carbon isomers. Also discussed are the structure, stability, and properties of larger clusters with a few such encapsulated-carbon units, with pronounced effects due to aggregation.

Protective and restorative effects of a Commiphora mukul gum resin and triheptanoin preparation on the CCL-110 skin fibroblast cell line.

Coenzyme Q10 (CoQ10) is a major ingredient in skin care products because of its anti-wrinkle effects, although it has some side effects especially at higher amounts. In this study, we compare the anti-wrinkle related properties of CoQ10 and a proprietary Commiphora mukul gum resin (guggul) and triheptanoin preparation (GU-TC7). GU-TC7 is prepared with a supercritical CO2-co-solvent extraction with ethanol, standardized to 2% guggulsterones and triheptanoin, a triglyceride composed of three 7-carbon fatty acids. Treatment of CCL-110 skin fibroblasts with GU-TC7 demonstrates a mild proliferative effect compared to CoQ10 and increased type I collagen synthesis. Additionally, GU-TC7 inhibited matrix metalloproteinase-1 (MMP-1) expression in a dose-dependent manner at 20-100 µg mL⁻¹ and inhibited human elastase expression by more than 50% as compared to no elastase inhibition with CoQ10 treatment. These results suggest that GU-TC7 possesses properties that are applicable to the treatment of wrinkles and may be considered for its further evaluation in skin care products.