Orbital Band Research Articles

Theoretical Analysis of Photo- and Electrochemical Properties of Anatase Nano-Particles

Oxide nanoparticles, like TiO2 nanoparticles are often applied in electrodes and photocatalytic systems. We studied the electronic states around the bandgap in anatase-type TiO2 nanoparticles of different shapes with (101) and (001) facets using Density Functional based Tight Binding (DFTB) method. Previous calculation has already shown that most orbitals of the valence and conduction bands forms delocalized band-like orbitals, however there are a significant number localized states at the lower at edge of conduction band, too.The energy and position of these unoccupied localized orbitals can be controlled by the shape of the nanoparticle and these orbitals can play important contribution to both electrochemical and photochemical properties. TD-DFTB calculations showed that the optical spectrum around the band gap is dominated by few transition with large oscillator strength (see Figure), while most of the transitions give only a weak contribution. Figure 1

Controlling the optical and mechanical properties of polyvinyl alcohol using Ag2S semiconductor for environmentally friendly applications

In this work, the optical and mechanical properties of polyvinyl alcohol (PVA) composite have been controlled using Ag2S semiconductor for environmentally friendly applications. Different weight (wt.) ratios percentages (0, 0.01, 0.1, 0.5, 1.0, 5.0 and 10.0%) of Ag2S/PVA composites were prepared using solution casting technique. The prepared composite films were analyzed using a scanning electron microscope (SEM), X-ray diffraction (XRD), spectrophotometry and dynamic mechanical analyzer techniques. XRD measurements ensure the semi-crystalline structure of plain PVA and Ag2S/PVA composites. The optical properties including the absorption, transmittance, reflectance, absorption coefficient, extinction coefficient, refractive index and dielectric constant as a function of wavelength are studied. The deduced transition energy between molecular orbital band edges (Eg) of Ag2S/PVA composite films decreases from 5.39 eV to 1.06 eV as the wt. % ratio of Ag2S/PVA composite increases from 0 to 10.0%. This decrease in Eg is mainly attributed to the formulation of new energy levels between the polymer's molecular orbital band edges. The mechanical properties including storage modulus, loss modulus, stiffness and loss factor (tan δ) as a function of swept temperature have been investigated. The estimated glass transition temperature (Tg) of the prepared films decreases from 54.5 °C to 34.7 °C as the wt. % ratio of Ag2S/PVA composite increases from 0 to 10.0%. These novel results present Ag2S/PVA composites as an active candidate in environmentally friendly applications.

Designing of benzothiazole based non-fullerene acceptor (NFA) molecules for highly efficient organic solar cells

To enhance the efficiency of organic solar cells (OSCs), five non-fullerene π-conjugated acceptor molecules namely BTM1, BTM2, BTM3, BTM4 and BTM5 are designed from recently reported 16.5% efficient acceptor molecule BTP-Cl. The molecules in the present quantum chemical investigation consist of benzothiazole (BT) core with different chemical species on the terminal side. The optoelectronic study of BTM1-BTM5 reveals that BTM3 and BTM4 molecules are superior with respect to absorption range found at the wavelengths of 780 and 791 nm as compared to 746 nm of reference molecule BTP-Cl. Frontier molecular orbital (FMO) and transition density matrix (TDM) analysis are performed that give basic information about the distribution of charges among investigated molecules. All investigated molecules exhibit charge density spread over the entire molecules. The BTM4 and BTM5 molecules efficiently transfer their electron densities from highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) with narrow bandgaps of 1.86 eV and 2.14 eV respectively. The electron mobility for BTM3 (0.00527), BTM4 (0.005820) and BTM5 (0.00539) are found less than BTP-Cl (0.00643). Similarly, BTM5 gives the least value of hole mobility (0.00558) as compared to BTP-Cl (0.00803). The binding energies of these molecules are also observed less (0.28 eV, 0.29 eV and 0.33 eV for BTM3, BTM4 and BTM5) in gas phase than BTP-Cl (0.35 eV). Also, BTM5 is tested with donor polymer PTB7-Th that provides further evidence for their interactions. It turned out that the structural tailoring at terminals can tune effectively the frontier molecular orbital energy levels, band gap, absorption spectra, open-circuit voltage, reorganization energy and binding energy value in investigated molecules. Our results suggest that the investigated molecules can serve as fine acceptor materials. Additionally, some investigated molecules can also be used as a hole and/or electron transport materials for OSCs.

Strain-induced majority carrier inversion in ferromagnetic epitaxial LaCoO3−δ thin films

Tensile-strained $\mathrm{LaCo}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ thin films are ferromagnetic, in sharp contrast to the zero-spin bulk, although no clear consensus has emerged as to the origin of this phenomenon. While magnetism has been heavily studied, relatively little attention has been paid to electronic transport, due to the insulating nature of the strain-stabilized ferromagnetic state. Here, structure, magnetism, and transport are studied in epitaxial $\mathrm{LaCo}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ films (10--22-nm thick) on various substrates (from 1.4% compressive to 2.5% tensile strain), using synchrotron x-ray diffraction, scanning probe and transmission electron microscopy, magnetometry, polarized neutron reflectometry, resistivity, and Hall effect. High quality, smooth films are obtained, exhibiting superstructures associated with both oxygen vacancy ordering and periodic in-plane ferroelastic domains. Consistent with prior work, ferromagnetism with an approximately 80--85 K Curie temperature is observed under tension; polarized neutron reflectometry confirms a relatively uniform magnetization depth profile, albeit with interfacial dead layer formation. Electrical transport is found to have similar semiconducting nature to bulk, but with reduced resistivity and activation energy. Hall effect measurements, however, reveal a striking inversion of the majority carrier type, from $p$-type in the bulk and under compression to n-type under tension. While thus far overlooked, ferromagnetism in epitaxial $\mathrm{LaCo}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ films is thus directly correlated with $n$-type behavior, providing important insight into the ferromagnetic state in this system. Aided by density functional theory calculations, these results are interpreted in terms of tensile-strain-induced orbital occupation and band structure changes, including a rapid decrease in effective mass at the ${e}_{g}$-derived conduction band minimum, and corresponding increase at the valence band maximum.

Enhanced valleytronic properties in germanene by direct proximity to heavy metal layer

Germanene, though with Dirac valleys, is not deemed as a good valleytronic material due to its minute band gap, negligible spin–orbit coupling and spatial inversion symmetry. In comparison of interfacing germanene with MoS2, we proposed that forming heterostructure with Tl2S, an anti-MoS2 material with two outer heavy metal layers, could be more effective in raising spin–orbit coupling and band gap in germanene due to the direct Ge-metal contact. By carrying out first-principles calculations, we studied the valleytronic properties of germanene enhanced by monolayer Tl2S. It is found that the Ge–Tl direct interaction is strong to a proper extent so that the valleys of germanene still persist and simultaneously the valley gap is drastically increased from 23 to 370 meV. The valley spin splitting, being zero in pristine germanene, become 45 meV, which is opposite at inequivalent valleys owing to the time reversal symmetry. The inversion symmetry of germanene is broken by Tl2S, resulting in large Berry curvature near the valleys and hence laying the ground for Berry phase physics in germanene, e.g., valley spin Hall effect and valley–spin locking, as revealed in our study. The calculations found a perfect valley-selective circular dichroism, by which the valley and spin degrees of freedom can be manipulated selectively and correlatively.

Electronic structure and x-ray magnetic circular dichroism in ferroelectric CaMnTi2O6

We study the electronic and magnetic properties of ferroelectric ${\mathrm{CaMnTi}}_{2}{\mathrm{O}}_{6}$ within density functional theory using the generalized gradient approximation (GGA) with the consideration of strong Coulomb correlations $(\mathrm{GGA}+U)$ in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band structure method. The x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism (XMCD) at the Mn, Ti ${L}_{2,3}$, and O $K$ edges have been investigated theoretically. The calculated results are in good agreement with experimental data. The core-hole effect in the final state as well as the effect of the electric quadrupole ${E}_{2}$ and magnetic dipole ${M}_{1}$ transitions have been investigated. The core-hole effect has improved the agreement with the experimental XAS and XMCD spectra at the Ti and Mn ${L}_{2,3}$ edges.

New quaternary selenides Tl4Sb8Sn5Se24 and Tl5Sb2Sn4Se14−x (x=0.5)

Abstract Synthesis, structural characterization and chemical bonding peculiarities of two new quaternary selenides of the Tl4Sb8Sn5Se24 and Tl5Sb2Sn4Se14−x (x = 0.5) are reported. The crystal structures of these compounds were determined by single crystal X-ray diffraction analysis. The Tl4Sb8Sn5Se24 phase is a new structure type and crystallizes in the triclinic P 1̅ space group (a = 7.9061(13) Å, b = 13.9035(16) Å, c = 21.4665(17) Å, α = 80.058(8)°, β = 84.727(10)°, γ = 73.542(12)°, wR 2 = 0.0258, 8200 F 2 values, 373 variables). The Tl5Sb2Sn4Se14−x (x = 0.5) phase represents a new structure type with a tetragonal unit cell (P 4/mbm, a = 8.1570(10) Å, c = 21.946(3) Å, wR 2 = 0.0346, 1953 F 2 values, 44 variables). Crystallographic analysis together with linear muffin-tin orbital band structure calculations reveals that both structures we conform to the concept of Zintl-Klemm and exhibit semiconductor properties.

Gas sensing mechanism of dissolved gases in transformer oil on Ag–MoS2 monolayer: A DFT study

Abstract Based on the density functional theory (DFT), the adsorption capabilities and electronic properties of Ag–MoS2 monolayer were discussed to fully discover the gas sensing performance to transformer oil decomposed gases (H2, CO, CH4, C2H6, C2H4 and C2H2). Specifically, the adsorption structure, adsorption energy, Mulliken charge analysis, deformation charge density, density of state (DOS), frontier molecular orbital analysis and band structure were explored. The analysis results illustrate that the adsorption to CO, C2H4 and C2H2 is strong, which is superior to the adsorption of H2, CH4 and C2H6. The narrower band gaps and increased electrical conductivity in all adsorption structures indicate that Ag–MoS2 monolayer is promising for the detection of studied gases. Therefore, the present study proposes an effective gas-sensing material to estimate the working state and insulation level of power transformers.

Orbital hybridization-induced band offset phenomena in NixCd1-xO thin films.

Herein, we present the cationic impurity-assisted band offset phenomena in NixCd1-xO (x = 0, 0.02, 0.05, 0.1, 0.2, 0.4, 0.8, and 1) thin films and further discuss them based on orbital hybridization modification. The compositional and structural studies revealed that the cationic substitution of Cd2+ by Ni2+ ions leads to a monotonic shift in the (220) diffraction peak, indicating the suppression of lattice distortion, while the evolution of local strain with an increase in Ni concentration is mainly associated with the mismatch in the electronegativity of the Cd2+ and Ni2+ ions. In fact, Fermi level pinning towards the conduction band minimum takes place with an increase in the Ni concentration at the cost of electronically compensated oxygen vacancies, resulting in the modification of the distribution of carrier concentration, which eventually affects the band edge effective mass of the conduction band electrons and further endorses band gap renormalization. Besides, the appearance of a longitudinal optical (LO) mode at 477 cm-1, as manifested by Raman spectroscopy, also indicates the active involvement of electron-phonon scattering, whereas modification in the local coordination environment, particularly anti-crossing interaction in conjunction with the presence of satellite features and shake-up states with Ni doping, was confirmed by X-ray absorption near-edge and X-ray photoelectron spectroscopy studies. These results manifest the gradual reduction of orbital hybridization upon the incorporation of Ni, leading to a decrement in the band edge effective electron mass. Finally, the molecular dynamics simulation reflected a 13% reduction in the lattice parameter for the NiO thin film compared to the undoped film, while the projected density of states calculation further supports the experimental observation of reduced orbital hybridization with an increase in Ni concentration.

Density functional theory analysis of electronic properties correlated with the biological activities of naturally occurring biomolecular system: Isodihydrocadambine

The atomic charge distribution, dipole moment, highest occupied-lowest unoccupied molecular orbital energy band gap, molecular electrostatic potential surface (MESP), UV–Visible spectra and (1H, 13C) chemical shifts in NMR spectra using density functional theory at B3LYP/6–31 + G(d,p) hybrid functional-basis set combination have been calculated in the case of Isodihydrocadambine (C27H34N2O10) which is reportedly biologically active natural compound. The molecular docking has also been performed to predict the expected biological activities of this bio-molecule and an attempt has been made to correlate the investigated electronic properties with the spontaneously originated bioactivity within it. The total dipole moment ≈ 2.02debye; reasonably low HOMO−LUMO energy band gap (≈3.89 eV) and MESP surface to be a chemically reactive site suited for drug activity have been observed in this bio molecule. The theoretical NMR spectroscopic characteristics agree with their experimentally evaluated values. The highest peak in UV–visible spectra has been calculated to be occurred at 284 nm arising due to HOMO-2 → LUMO + 2, HOMO-1 → LUMO + 1, HOMO → LUMO + 1, HOMO → LUMO + 2 electronic transitions. This bio molecule has been screened for the binding with the variety of protein receptors (1GCN, 2NMO and 3I40) which reveals that it possesses multifarious biological activity correlated with the behavior of its MESP surface and HOMO−LUMO band gap.

Experimental realization of Mott insulator of ultracold <sup>87</sup>Rb atoms in two-dimensional optical lattice

Quantum phase transition of ultracold atomic gas is one of the core contents in the study of quantum correlational many-body systems. In this paper, two-dimensional (2D) optical lattices are generated by a single fold retroreflected laser beam, and this scheme is used to experimentally design and implement the 2D optical lattice of double wells suitable for isolating and manipulating an array of individual pairs of atoms and predict a topological semimetal in the high orbital bands in this 2D lattice. Two types of optical lattice structures are produced by controlling the laser polarization. One type is the usual 2D optical lattice, which is formed by two independent one-dimensional(1D) optical lattices in two directions and named in-plane lattice, and the other type is the lattice that is formed by the interference between two one-dimensional optical lattices in two directions and called out-plane lattice. When <sup>87</sup>Rb BEC (Bose-Einstein condensation) is loaded into the 2D optical lattice, the quantum phase transition between superfluid state and Mott insulator state is observed by controlling the tunneling and in-site interaction. And the phase transition from superfluid state to Mott insulator is judged by observing whether there are interferential lattice points in momentum space. The lattice depths of two cases can be calibrated by Kapitza-Dirac scattering in the ultracold atomic experiment through the time-of-flight absorption imaging. In the in-plane optical lattice, some incorrect points appear in the 45° direction, because the linear polarization degree of beam is impure after being reflected by mirrors and two direction of beam are not completely orthogonal to each other. It is obvious that the two cases have different phase transition points, which is due mainly to the difference in structure. For the in-plane lattice, there are two independent 1D optical lattices, and for the out-plane lattice, the two direction beams mutually interfere with each other, therefore, two optical lattices are not independent of each other. The atoms come back to BEC by reducing the potentials of optical lattice to zero; the temperature of system is slightly higher, because of the jitter of the light lattice. The different behaviors of quantum phase transition are analyzed for two types of optical lattices. This work will provide a platform for the future study of large spin system and strong correlation physics in optical lattices.

Structural, vibrational and electronic spectroscopic study of 6-hydroxycoumarin using experimental and theoretical methods.

Understanding the photochemical behavior of structural isomers of hydroxycoumarin (HC) having different properties of consequence in biological activities demand spectroscopic information of this class of compounds. Barring 6-hydroxycoumarin (6-HC), other isomers of HC's are well studied spectroscopically. To understand and compare the photochemical activity of 6-HC with other isomers, a detailed study of this molecule has been taken up. For this purpose, electronic, vibrational and structural properties of 6-HC have been studied using ultraviolet absorption and Infrared spectroscopy techniques. Quantum chemical calculations have been performed at DFT/B3LYP level of theory to get the optimized geometry and vibrational frequencies of normal modes to support and analyze experimental data. The detailed vibrational assignments were made on the basis of potential energy distributions. Chemical activity, molecular orbital energies, band gap and hyper-polarizability information have been computed from quantum chemical simulations. NBO analysis helped in understanding the stability of the molecule arising from hyper-conjugative interaction and charge delocalization. UV-Visible spectrum of the compound was recorded in the region 300-600nm helped in obtaining band gap data of the compound. Molecular Electrostatic Potentials (MESP) were plotted and the respective centers of electrophilic and nucleophilic attacks were predicted with the help of Fukui functions calculations. Further, it was observed that the negative electrostatic potential regions are mainly localized over the oxygen atoms and the positive regions are localized over the benzene ring. Details of the results and analysis of experimental and theoretical spectroscopy studies are presented in this paper.

Experimental and DFT Studies on Thermochromism Induced Binary HBLC Mixture

Novel linear double hydrogen-bonded liquid crystals (HBLCs) were derived from diglycolic acid (DGA, a non-mesogenic compound) and 4-n-alkoxybenzoic acids (nOBA, n = 7 and 8 mesogenic compounds). Hydrogen bond (H bond) formation and its vibrational stretching frequencies had been calculated by experimental and theoretical IR spectroscopy. The calculated band gap energy (4.96 eV) using a UV-Vis spectrum clearly reveals the coincidence of highest occupied molecular orbital-lowest unoccupied molecular orbital band energy of the present HBLC mixture. Further, X-ray diffraction (XRD) studies at room temperature confirm the monoclinic nature of the HBLC mixture. Mesophases and their transition temperature were studied by a polarized optical microscope (POM) and differential scanning calorimetry (DSC). The order of the phase transition was evaluated by the thermal analysis. Due to the rotary motion of molecules, nematic phase (threaded texture) with thermochromic effect was observed. The induced thermochromism in the present HBLC and its possible color recording applications were discussed. Molecular descriptors (using computational density functional theory (DFT)) of the present mixture indicate the hardness and softness of the HBLC mixture. Natural bond orbital (NBO) studies revealed the O–H…O stabilization energy in the present HBLC mixture. Also, the lone pair (LP)-to-π* transition confirms the existence of intermolecular hydrogen bonding in the HBLC mixture. The calculated band gap energy of the DGA + nOBA HBLC mixture is a more useful parameter to identify suitable hydrogen-bonded liquid crystal material for photonic applications. Mulliken analysis shows clear evidence of the charge distribution in different molecules of the HBLC system.

Synthesis and properties of bay unilaterally extended and mono-substituted perylene diimides

The synthesis of two sulfur-decorated perylene diimides, the five-membered S-heterocyclic annulated perylene diimide (1) and 1-propanethiol- N,N′-dicyclohexylperylene-3,4,9,10-tetracarboxylic diimide (2), and a novel sulfoxide-containing perylene diimide, 1-propyl sulfoxide- N,N′-dicyclohexylperylene-3,4,9,10-tetracarboxylic diimide (3), are reported. The photophysical, electrochemical, aggregation, and thermal properties of these compounds are investigated by ultraviolet visible absorption, fluorescence, cyclic voltammetric, X-ray diffraction, and thermogravimetric analysis techniques. The geometries of the compounds are optimized at the 6-31G* level of theory using density functional theory, and their potentials are correlated with molecular orbitals. The prepared perylene diimide derivatives exhibit narrow the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals band gaps, and they have quite different absorptions and emissions in dichloromethane solutions, which are in agreement with the density functional theory–calculated results.

Computational study on optoelectronic and charge transport properties of diketopyrrolopyrrole-based A-D-A-D-A structure molecules for organic solar cells.

Eight novel diketopyrrolopyrrole (DPP)-based A-D-A-D-A structure molecules were designed for organic solar cells (OSCs) applications. In these molecules, the electron-deficient DPP and dicyanovinyl groups were used as the acceptor groups and different planar electron-rich groups were employed as the donor π-bridges. Applying the B3LYP/6-31G (d,p) and TD-B3LYP/6-31G (d,p) methods, the optoelectronic and charge transport properties were investigated. It turned out that the different π-bridges can tune effectively the frontier molecular orbital energy levels, band gap, and absorption spectra. Furthermore, the different π-bridges also affect the charge transport properties of the designed molecules. Our results suggest that the investigated molecules can serve as donor materials. Additionally, some investigated molecules can also be used as hole and/or electron transport materials for OSCs. Graphical abstract A series of novel A-D-A-D-A molecules are investigated systematically. The optical and electronic properties can be tuned effectively by the π-bridges. All derivatives can be used as donor materials for OSCs. Some designed molecules can be used as hole and/or electron transport materials. The different π-bridges do not significantly affect the stability of the molecules.

Synthesis of Zr-coordinated amide porphyrin-based two-dimensional covalent organic framework at liquid-liquid interface for electrochemical sensing of tetracycline

Highly-conductive two-dimensional covalent organic framework (COF) displays prominent applications in various fields of science and technology. This paper reports the design and liquid-liquid interface synthesis of a novel Zr-coordinated amide porphyrin-based 2D COF (Zr-amide-Por-based 2D COF). The COF adopts a graphene-like multilayer structure with the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) band gap of 1.6 eV. The ordered multilayer structure of the amide COF was confirmed through a series of characterization techniques, including scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In particular, the inherent-ordered structure of Zr-amide-Por-based 2D COF with Zr as the catalytically active center confers several distinct advantages to the material, such as high conductivity and high electrocatalysis performance. A molecularly imprinted tetracycline electrochemiluminescence sensor was constructed based on the Zr-amide-Por-based 2D COF, and gate control effect was used as a signal-generation mechanism. Under optimal conditions, the sensor showed a good linear relationship with tetracycline in the concentration range of 5–60 pM, with a detection limit of 2.3 pM. Because the sensor is rapid, cost-efficient, highly sensitive, and specific, it can be considered as a viable platform for veterinary drug residue monitoring.

Investigation of Sodium Plating and Stripping on a Bare Current Collector with Different Electrolytes and Cycling Protocols.

In the present study, stable sodium plating/stripping has been achieved on a bare aluminum current collector, without any surface modifications or artificial SEI deposition. The crucial role of predeposited sodium using cyclic voltammetry on bare aluminum as a matrix for plating/stripping has been highlighted using different protocols for cycling. The predeposition strategy ensures stable and efficient cycling of sodium in anode-free sodium batteries without dendritic formations. The study highlights the difference of sodium plating/stripping in carbonate and glyme solvent electrolytes on the bare aluminum current collector. Contrary to the carbonate solvent electrolyte, the cell with the tetraglyme solvent electrolyte and sodium loading of 1 mA h/cm2 has an overpotential under 20 mV during the sodium plating/stripping cycles at 0.5 mA/cm2 for a testing period of 650 h. Overpotentials under 40 and 100 mV have been achieved at current densities up to 1 and 2 mA/cm2 for loadings up to 5 and 10 mA h/cm2, respectively, for a testing time up to 1500 h. Density functional theory simulations have been performed to obtain the solvation energies, and the highest occupied molecular orbital-lowest unoccupied molecular orbital band gap of the solvent-sodium ion complexes for the glyme solvent electrolytes and their trends have been correlated with the experimental observations.

Computational and spectral studies of 3,3'-(propane-1,3-diyl)bis(7,8-dimethoxy-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one)

Detection and qualification of unknown impurities during commercial drug synthesis have been mandated by the regulatory authorities. 3,3'-(propane-1,3-diyl)bis(7,8-dimethoxy-1,3,4,5-tetrahydro-2H-benzo [d]azepin-2-one) in short IVA-9, is one such process-related impurity formed during the synthesis of cardiotonic drug Ivabradine. The structure and properties of this molecule have not been explored yet. A suggestive reaction route for the chance formation of IVA-9 during the commercial synthesis of parent drug molecule has been reported in this article. Further, the optimized geometry and vibrational studies have been computed using Gaussian 09. Experimental FTIR scan has also been performed and values show satisfactory consilience with the computational data. The frontier orbital energies and energy band gaps of the reaction fragments and products were computed. The evaluation of ADME parameters such as absorption, distribution, metabolism, and excretion are performed using SwissADME tool to assess the drug-likeness and medicinal chemistry friendliness. Six physiochemical parameters namely flexibility, lipophilicity, size, polarity, solubility and saturation and their critical limits are depicted using the bioavailability radar of the programme to provide insights into pharmacokinetic properties such as human gastrointestinal absorption (HIA), blood-brain-barrier (BBB) permeability, total polar surface area (TPSA) and inhibitor action to important cytochromes etc.

Histopathologic study of accessory orbital band in type I Duane syndrome

Histopathologic study of accessory orbital band in type I Duane syndrome

Realizing nearly-free-electron like conduction band in a molecular film through mediating intermolecular van der Waals interactions

Collective molecular physical properties can be enhanced from their intrinsic characteristics by templating at material interfaces. Here we report how a black phosphorous (BP) substrate concatenates a nearly-free-electron (NFE) like conduction band of a C60 monolayer. Scanning tunneling microscopy reveals the C60 lowest unoccupied molecular orbital (LUMO) band is strongly delocalized in two-dimensions, which is unprecedented for a molecular semiconductor. Experiment and theory show van der Waals forces between C60 and BP reduce the inter-C60 distance and cause mutual orientation, thereby optimizing the π-π wave function overlap and forming the NFE-like band. Electronic structure and carrier mobility calculations predict that the NFE band of C60 acquires an effective mass of 0.53–0.70 me (me is the mass of free electrons), and has carrier mobility of ~200 to 440 cm2V−1s−1. The substrate-mediated intermolecular van der Waals interactions provide a route to enhance charge delocalization in fullerenes and other organic semiconductors.