Boron Nitride Cages Research Articles

A Series of Endohedral Metallo-BN Fullerene Superatomic Structures.

Superatoms are crucial in the assembly of functional and optoelectronic materials. This study investigates the endohedral metallo-boron nitride [boron nitride (BN)] fullerenes U@B12N12, Cm@B12N12, and U@B16N16 in theory. Our findings confirm that U@B12N12, Cm@B12N12, and U@B16N16 are superatoms and their electronic configurations are 1P61S21D101F142P62S22D102F123P6, 1P61S21D101F141G161H162S22P62D102F12, and 1P61S21D101F142P62S22D102F14, respectively. Notably, the orbital energy levels in these superatoms exhibit a flipping phenomenon, deviating from those of previous superatom studies. Further, the orbital composition analyses reveal that superatomic orbitals 1S, 1P, 1D, and 1F mainly originate from BN cages, whereas the 2S, 2P, 2D, 2F, and 3P superatomic orbitals arise from hybridizations between BN cage orbitals and the 7s, 7p, 6d, and 5f orbitals of actinide atoms. And the energy gap of endohedral metallo-BN fullerene superatoms is reduced by introducing actinide atoms. Additionally, the analyses of ionization potentials and electron affinities show that U@B12N12, Cm@B12N12, and U@B16N16 have lower ionization potentials and higher electron affinities, suggesting decreased stability compared to that of pure BN cages. This instability may be linked to the observed flipping of the superatomic orbital energy levels. These insights introduce new members to the superatom family and offer new building blocks for the design of nanoscale materials with tailored properties.

Density functional theory (DFT) study of non-linear optical properties of super salt doped boron nitride cage

The optical and nonlinear optical (NLO) properties of pure boron nitride (BN) cage and super salt (OLi3NO3) doped BN complexes were investigated in this research work utilizing the rB3LYP/6-31G(d,p) density functional theory (DFT) approach. The response mechanism is examined through geometric parameters, frontier molecular orbital (FMO), hyperpolarizabilities, dipole moments (μ), the density of states (DOS), and natural bonding orbital (NBO). Non-covalent interactions (NCl), and infrared spectroscopic (IR) study have been performed to evaluate the nature of interactions and vibrational frequencies of all complexes. As compared to the pure BN surface, the electron transport characteristics of doped complexes were significantly improved when bandgap energies Eg lowered from 6.84 eV to 5.33 eV. The [email protected] demonstrates a considerable increase in the linear polarizability (α0) (248.56 au), and first hyperpolarizability (β0) (553.87 au), because of lower excitations energies as compared to the BN surface (α0=143.01, and β0=29.49). The designed complex [email protected] demonstrated the outstanding NLO properties and observed to be beneficial for constructing future NLO materials.

DFT investigation on the application of pure and doped X12N12 (X = B and Al) fullerene-like nano-cages toward the adsorption of temozolomide.

The sensitivity of pure and doped X12N12 (X = B and Al) fullerene-like nano-cages (FLNs) toward the anti-cancer drug temozolomide (TMZ) is probed herein at DFT/M06-2X-D3/6-311G(d,p) theoretical level in both gas phase and water. A noticeable affinity of the FLNs toward TMZ was observed along with the negative gas-phase adsorption energies −1.37 and −2.09 eV for the most stable configurations of pure B12N12 and Al12N12 pristines, respectively. Considerable charge transfer from TMZ to the FLNs was also revealed via NBO analysis and the Hirshfeld atomic charges, making the dipole moment vector of the molecular complexes to be oriented from the nano-cages to the TMZ moiety. Furthermore, a percentage decrease in the HOMO-LUMO energy gap (ΔEg) of 38.09 and 17.72% was obtained for the B12N12 and Al12N12 nano-cages, respectively. The percentage change in ΔEg was found to be reduced upon doping and solvation of the FLNs. Finally, a recovery time in vacuum ultraviolet light of 1.06 s is found for the complex with pure B12N12, which in addition to the above-mentioned parameters make this boron nitride cage the best sensor for TMZ, among the FLNs considered in the present work.

Fluorinated carbon and boron nitride fullerenes for drug Delivery: Computational study of structure and adsorption

We applied a genetic algorithm combined with the B3LYP/6-311G** approach to determine the structures of low-energy isomers of partially fluorinated fullerenes, the number of which is combinatorically huge. We found that the effective interaction of fluorine atoms on the fullerene surface can not be described within the pair approximation with sufficient accuracy. For the smallest C20 fullerene, the most robust bonding with fluorine was observed in the C20F2 isomer, whereas further fluorination was less feasible. For C60 fullerene, the most thermodynamically stable isomers were C60F2 and C60Fm with m about 40. Effective attraction energy of adsorbed fluorine atom with OH, NH2, and COOH functional groups on the C60 fullerene surface is about 1.24 eV. Vibration analysis of the stable C60Fm isomers clarified the frequencies shifts during the gradual fluorination. As to fluorinated derivatives of boron nitride cages, some of them possess extreme distortions under low fluorination. However, half- and fully-fluorinated BN fullerenes demonstrate moderate strain and strong van-der-Waals interaction with doxorubicin drug. Loading of doxorubicin on both carbon and boron nitride fullerenes with varying degrees of fluorination confirmed that fluorine concentration defines the energy of the fullerene-drug interaction. A half-fluorinated B12N12F12 cage provides the most substantial adsorption, as the fluorine atoms on its surface are more moveable and can “adjust” to the DOX molecule.

First-principles study of luminescence of fullerene-like clusters

Thermally activated delayed fluorescence (TADF), a unique molecular fluorescence mechanism, plays a key role in designing emitters of high efficiency. Carbon fullerenes such as C<sub>60</sub> and C<sub>70</sub> exhibit strong TADF with intensity even higher than that of the prompt fluorescence, owing to their long lifetimes of triplet state and modest singlet-triplet energy gaps. Thus, there arises the intriguing question whether other fullerene-like clusters can also have fluorescence and host the TADF effect. In this work, by time-dependent density functional theory (TD-DFT) calculations, we explore the excited-states of the experimentally reported boron nitride cage clusters B<sub>12</sub>N<sub>12</sub>, B<sub>24</sub>N<sub>24</sub> and B<sub>36</sub>N<sub>36</sub>, as well as compound clusters B<sub>12</sub>P<sub>12</sub>, Al<sub>12</sub>N<sub>12</sub> and Ga<sub>12</sub>N<sub>12</sub> with the same geometry as B<sub>12</sub>N<sub>12</sub>. Using the HSE06 hybrid functional, the predicted energy gaps of these fullerene-like clusters are obtained to range from 2.83 eV to 6.54 eV. They mainly absorb ultraviolet light, and their fluorescence spectra are all in the visible range from 405.36 nm to 706.93 nm, including red, orange, blue, and violet emission colors. For the boron nitride cages, the energy gap of excited states increases with the cluster size increasing, accompanied by a blue shift of emission wavelength. For the clusters with B<sub>12</sub>N<sub>12</sub> geometry and different elemental compositions, the excited energy gap decreases as the atomic radius increases, resulting in a red shift of emission wavelength. In addition, the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) of these compound cage clusters are distributed separately on different elements, resulting in small overlap between HOMO and LUMO wavefunctions. Consequently, these fullerene-like clusters exhibit small singlet-triplet energy differences below 0.29 eV, which is beneficial for the intersystem crossing between the excited singlet state and triplet state, and hence promoting the TADF process. Our theoretical results unveil the fluorescence characteristics of cage clusters other than carbon fullerenes, and provide important guidance for precisely modulating their emission colors by controlling the cluster sizes and elemental compositions. These experimentally feasible fullerene-like compound clusters possess many merits as fluorophors such as outstanding stabilities, non-toxicity, large energy gap, visible-light fluorescence, and small singlet-triplet energy gap. Therefore, they are promising luminescent materials for applications in display, sensors, biological detection and labelling, therapy, and medicine.

2 + 2] Cycloaddition and Bond Cleavage of Boron Nitride Cages with Iminoborane: A DFT Study

We have studied the addition of reaction between iminoborane HBNH with the BnNn cages (n = 12, 16, 28 and 36) for the chemoselectivity (BN bond cleavage and expansion ring vs [2 + 2] cycloaddition) and regioselectivity (square–hexagon junctions vs hexagon–hexagon) of the reaction. Based on our results, the iminoborane molecule can either selectively break a B–N bond of the BN cages, expanding the square ring of the BN cage to a larger one at the surface, or undergo a [2 + 2]-cycloaddition on the BNNT surface. These reactions exhibit a depending on the reactive site of the cages. The square–hexagon B–N bond of the cages prefer bond-cleavage-ring-expansion processes, while hexagon–hexagon B–N bonds follow [2 + 2] cycloaddition reaction. Overall, all reactions are is exothermic while bond-cleavage-ring-expansion processes are a bit more favorable than [2 + 2] cycloadditions with smaller barrier heights. While complexes of iminoborane with hexagon–hexagon bonds at the middle of the larger cages resemble [2 + 2]-cycloaddition, BN bond cleavage also occurred and HBNH acts as a bridge at the top of the decagon. The larger values of HOMO–LUMO gaps for the most stable configurations also indicate kinetically preference the BN bond cleavage and ring expansion processes than the [2 + 2]-cycloaddition reactions.

Adsorption of Tetryl on the Surface of B12N12: A Comprehensive DFT Study

In this study, the adsorption of tetryl on the surface of boron nitride cage was evaluated by density functional theory. For this purpose, the structures of tetryl, B12N12, and the tetryl-B12N12 complexes were geometrically optimized. Then, IR and frontier molecular orbital calculations were performed on them. The calculated adsorption energies, Gibbs free energy changes (ΔGad), adsorption enthalpy changes (ΔHad) and thermodynamic equilibrium constants (Kth) revealed that the adsorption process of both explosives is experimentally feasible, spontaneous, exothermic and non-equilibrium. The specific heat capacity values (CV) showed that the heat sensitivity has been significantly reduced in the tetryl complexes with B12N12. The N-O and C-N bond lengths and the density values demonstrated that tetryl-derived products with boron nitride cage have higher explosive velocity and blasting pressure in comparison to the pure blasting materials without B12N12. The frontier molecular orbital parameters such as band gap, chemical hardness, electrophilicity, chemical potential and charge capacity were also studied and the results proved that boron nitride cage is an ideal electroactive sensing material in order to fabricate novel sensors for the determination of tetryl.

Stability, electronic and optical properties of the boron nitride cage (B47N53) from quantum mechanical calculations

The structural, electronic and optical properties of an isomer proposed for the boron nitride cage (BN; BxNy; x = 47, y = 53) in the gas phase were carried out by means of DFT calculations. The results of the quantum simulations indicate there is not magnetism associated to the stable structure with neutral charge. However, the system exhibits a high cohesion energy (−6.08 eV/atom), this feature is relating to its high chemical stability. The quantum descriptors indicate a moderate polarity, low chemical reactivity as well as low work function for this nano-cage. This system has electronic behavior like-conductor, opposite to others BN nanostructures. On the other hand, the electronic absorption spectrum was obtained using six density functionals under the formalism of the time-dependent DFT and show a good agreement with the experimental data, these calculations reveal a strong absorption band at ≈ 260 nm in the UV region. The natural transition orbitals suggest an intramolecular charge transfer inside of BN cage, and the laplacian of the electron density evaluated in the bond critical points confirms that the cage is stabilized by the presence of homo-nuclear bonds BB and NN.

Fullerene-like boron nitride cages BxNy (x + y = 28): stabilities and electronic properties from density functional theory computation.

Computations based on density functional theory (DFT) were performed to get insights into the structural stability, electronic, and magnetic properties of fullerene-like boron nitride cages (f-like BNCs) for different BxNy chemical stoichiometry (x + y = 28). The results reveal at least metastable nanostructures for anionic charge (Q = -1) and doublet state (M = 2); furthermore, a magnetic moment of 1.0 bohr magneton is associated with them. These systems, in general, have high chemical stability due to their large values of cohesion energy, and the structural stability was corroborated by means of vibrational calculations. According to quantum descriptors, they exhibit high polarity (except to B27N and B28 systems), low average chemical reactivity and average work function, and electronic behavior like semiconductors. Therefore, the properties of these systems are improved compared to the B28 system, and thus the nonstoichiometry fullerenes can be used for more applications than the pristine one.

Activation of CO and CO2 on homonuclear boron bonds of fullerene-like BN cages: first principles study.

Using density functional theory we investigate the electronic and atomic structure of fullerene-like boron nitride cage structures. The pentagonal ring leads to the formation of homonuclear bonds. The homonuclear bonds are also found in other BN structures having pentagon line defect. The calculated thermodynamics and vibrational spectra indicated that, among various stable configurations of BN-60 cages, the higher number of homonuclear N-N bonds and lower B:N ratio can result in the more stable structure. The homonuclear bonds bestow the system with salient catalytic properties that can be tuned by modifying the B atom bonding environment. We show that homonuclear B-B (B2) bonds can anchor both oxygen and CO molecules making the cage to be potential candidates as catalyst for CO oxidation via Langmuir–Hinshelwood (LH) mechanism. Moreover, the B-B-B (B3) bonds are reactive enough to capture, activate and hydrogenate CO2 molecules to formic acid. The observed trend in reactivity, viz B3 > B2 > B1 is explained in terms of the position of the boron defect state relative to the Fermi level.

ChemInform Abstract: Carbon Doped Boron Nitride Cages as Competitive Candidates for Hydrogen Storage Materials.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Carbon doped boron nitride cages as competitive candidates for hydrogen storage materials

By the incorporation of C atoms into (BN)(12) fullerene, our theoretical investigation shows that carbon doped boron nitride cages (BNC) can achieve a high hydrogen storage amount of 7.43 wt%, and dehydrogenation of the corresponding BNC hydrides (BNC(H)) is thermodynamically favored for practical applications of hydrogen energy, making BNC competitive candidates for hydrogen storage materials.

Purification of Single-Walled Boron Nitride Nanotubes and Boron Nitride Cages

Continuous laser vaporization of a BN target under N2 atmosphere is up to now the unique route to single-walled boron nitride nanotubes (BN-SWNTs). Although grams of product can be obtained by this technique, the raw material contains in addition to the BN-SWNTs, different by-products made of boron and nitrogen. Since these materials are undesirable for the studying of the intrinsic properties of the nanotubes, we have undertaken a purification process using chemical and physical methods to separate the different components. We show here that most impurities can be removed by successive cycles of washing, sonication, and centrifugation. Furthermore, the two different types of boron nitride nanostructures i.e., BN-SWNTs and BN-cages can be isolated. Efficiency of the separation was monitored by transmission electron microscopy (TEM) at the different steps of the process. Finally, we envisage the further purification of the nanotubes-enriched fraction by functionalizing the nanotubes in a non covalent manner by specific polymers as for carbon nanotubes and BN multi-walled nanotubes.

Theoretical Nitrogen NMR Chemical Shifts in Octahedral Boron Nitride Cages

We have calculated the geometrical structure, relative stability, and nitrogen chemical shifts of five boron nitride hollow octahedral cages using density functional theory. Our results show three typical ranges for nitrogen chemical shifts corresponding to each of the nonequivalent magnetic sites of the N atoms. The principal component of the electric field gradient tensor at each 14N site in boron nitride cages is predicted to be much smaller than the corresponding value in borazine, which should reflect in sharper spectral lines and much better resolution.

Boron nitride cages from B12N12 to B36N36: square–hexagon alternants vs boron nitride tubes

The structures and stabilities of square-hexagon alternant boron nitrides (Bx Nx , x=12-36) vs their tube isomers containing octagons, decagons and dodecagons have been computed at the B3LYP density functional level of theory with the correlation-consistent cc-pVDZ basis set of Dunning. It is found that octagonal B20N20 and B24N24 tube structures are more stable than their square-hexagon alternants by 18.6 and 2.4 kcal mol(-1), respectively, while the square-hexagon alternants of other cages are more stable. Trends in stability as a function of cluster size are discussed.

πelectronic structure of octahedral trivalent cages consisting of hexagons and squares

A zone-folding construction is applied to the honeycomb lattice band structure to yield explicit expressions for the H\"uckel $\ensuremath{\pi}$-molecular orbitals, energies and symmetries of trivalent polyhedra consisting of hexagons and squares [(4,6) cages] with octahedral symmetry. The ${A}_{1}$, ${A}_{2}$, and $E$ representations are accessible in this way, but not the ${T}_{1}$ and ${T}_{2}$ representations. Therefore, we have also performed numerical H\"uckel calculations on a large set of cages. A clear distinction in electronic structure between leapfrog, nonleapfrog type 1 and nonleapfrog type 2 cages is revealed. The results are relevant both for carbon cages and alternating boron-nitride cages. Quantum chemical calculations on ${\mathrm{C}}_{24}$, ${\mathrm{C}}_{56}$, ${\mathrm{C}}_{72}$, and ${\mathrm{B}}_{36}{\mathrm{N}}_{36}$ confirm the results.

Theoretical infrared, Raman, and optical spectra of theB36N36cage

The B36N36 fullerene-like cage structure was proposed as candidate structure for the single-shell boron-nitride cages observed in electron-beam irradiation experiment. We have performed all electron density functional calculations, with large polarized Gaussian basis sets, on the B36N36 cage. We show that the cage is energetically and vibrationally stable. The infra-red, Raman and optical spectra are calculated. The predicted spectra, in combination with experimentally measured spectra, will be useful in conclusive assignment of the proposed B36N36 cage. The vertical and adiabatic ionization potentials as well as static dipole polarizability are also reported.

Synthesis of huge boron nitride cages

Boron nitride (BN) cages were synthesized by annealing Fe 4N and B powders at 1000 °C for 1 h in nitrogen gas atmosphere. To remove non-BN clusters such as metal catalyst particles, purification of BN cages was carried out by acid treatment and centrifugation. Large amounts of BN cages were observed by high-resolution electron microscopy and energy-dispersive X-ray spectroscopy, and the cages showed photoluminescence peak at ∼3.8 eV.

Structure and stability of boron nitride cages

The structure and energy of boron nitrides (BN)n (n = 10−41), have been investigated theoretically. The most stable cages have been constructed on the basis of a simple design principle, and the predicated stability has been validated at the B3LYP/6-31G* level of theory. Among these, the Th, symmetrical (BN)12 cluster has been confirmed to be the most stable cage on the basis of the calculated disproportation energy and binding energy per BN unit.

Structure and stability of boron nitride cages

Structure and stability of boron nitride cages