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In this chapter, we presented an analysis of the recent advances in the applications of boron clusters in biomedical fields such as the development of biosensors and drug delivery systems on the basis of quantum chemical calculations. Biosensors play an essential role in many sectors, e.g., law enforcement agencies for sensing illicit drugs, medical communities for detecting overdosed medications from human and animal bodies, etc. The drug delivery systems have theoretically been proposed for many years and subsequently implemented by experiments to deliver the drug to the targeted sites by reducing the harmful side effects significantly. Boron clusters form a rich and colorful family of atomic clusters due to their unconventional structures and bonding phenomena. Boron clusters and their complexes have various biological activities such as the drug delivery, imaging for diagnosis, treatment of cancer, and probe of protein-biomolecular interactions. For all of these reactivities, the interaction mechanisms and the corresponding energetics between biomaterials and boron clusters are of essential importance as a basic step in the understanding, and thereby design of relevant materials. During the past few years, attempts have been made to probe the nature of these interactions using quantum chemical calculations mainly with density functional theory (DFT) methods. This chapter provides a summary of the theoretical viewpoint on this issue.

First-principles calculations based on density functional theory were utilized to evaluate whether an iron atom decorated B

Systematic density functional theory (DFT) calculations using the TPSSh functional and the def2-TZVP basis set were carried out to identify the global energy minimum structure of the Li2FeB14 cluster. Keeping the double ring tubular shape of FeB14, capping of two Li atoms leads to a teetotum form at a low spin state, in which the Fe atom is endohedrally covered by two B7 strings, and both Li atoms are attached to Fe along the C7 axis at both sides. Calculated results show that strong electrostatic interactions between 2Li+ and Fe2− arising from Li electron transfer upon doping particularly provide a key driving force for stabilizing this charge-transfer structure. The bonding pattern of the teetotum can be understood from the hollow cylinder model (HCM). TD-DFT calculations demonstrate that this cluster can also be regarded as a useful material for transparent optoelectronic devices. Furthermore, the Li2FeB14 superatom can be used as a building block for making boron-based nanowires with metallic character. Replacement of Li atoms by Mg atoms was also found to lead to nanowires.

In the current research, density functional theory calculations were carried out to investigate the potential application of bare and functionalized olympicene molecules (C19H12) as anode materials for Li-ion batteries. The interactions of Li and Li+ were studied with these molecules and the cell voltages were calculated. The results reveal that the cell voltage of this molecule is greater than some well-known carbon based materials such as C32, C60, C70 fullerenes and carbon nanotubes. The functionalization of C19H12 with the electron-donating groups such as OCH3, NH2, OH enhances the cell voltage. The OCH3 substituted olympicene exhibits the maximum cell voltage of 1.60 V, which is even greater than that of a (10,10) carbon nanotube.

The potential application of a single Fe atom decorated C 24 N 24 fullerene (Fe@C 24 N 24 ) as a highly active catalyst for the CO oxidation is investigated through the dispersion-corrected DFT calculations. Three different CO oxidation reaction pathways, including the Eley-Rideal (ER), the Langmuir-Hinshelwood (LH) and the termolecular Eley-Rideal (TER) are investigated comparably. Our results indicate that the CO oxidation would like to occur via the TER mechanism owing to its small activation energies. The calculated energy barrier for the rate-determining step of the TER pathway is 0.35 eV. The results reveal that Fe@C 24 N 24 can be regarded as an innovative metal-free catalyst for the low temperature oxidation of toxic CO.

The potential application of porphyrin‐like porous C24N24 fullerene decorated with a single Si atom (Si@C24N24) as a highly active catalyst for the reduction of NO in the presence of CO is investigated through the dispersion-corrected DFT calculations. The results reveal that NO can be simply reduced into N2O through the dimer mechanism. This reaction also produces Oads species which is attached to the Si atom. Thereafter, the Oads is eliminated by an incoming CO by overcoming small activation energy of 6.68 kcal/mol. These results demonstrate that the novel Si@C24N24 can be regarded as a pioneering metal-free catalyst for NO reduction.

This study focused on the theoretical viability of Ng

Systematic density functional theory (DFT) calculations using the TPSSh functional and the def2-TZVP basis set were carried out to identify the global energy minimum structure of the Li2FeB14 cluster. Keeping the double ring tubular shape of FeB14, capping of two Li atoms leads to a teetotum form at a low spin state, in which the Fe atom is endohedrally covered by two B7 strings, and both Li atoms are attached to Fe along the C7 axis at both sides. Calculated results show that strong electrostatic interactions between 2Li+ and Fe2- arising from Li electron transfer upon doping particularly provide a key driving force for stabilizing this charge-transfer structure. The bonding pattern of the teetotum can be understood from the hollow cylinder model (HCM). TD-DFT calculations demonstrate that this cluster can also be regarded as a useful material for transparent optoelectronic devices. Furthermore, the Li2FeB14 superatom can be used as a building block for making boron-based nanowires with metallic character. Replacement of Li atoms by Mg atoms was also found to lead to nanowires.

A systematic exploration of the potential energy surface through evolutionary search algorithms was carried out to identify the most stable B27Sc2+ structure. A nearly perfect boron box was found featuring a triple ring tubular shape with high D9h symmetry formed by three B9 strings connected with each other and the box is capped by an Sc-Sc dimer. Each Sc atom is placed at the centre of a B9 terminal string along the C9 axis. The shapes of the MOs of the B27+ triple ring are reproduced by eigenstates of a simple model of a particle on a hollow cylinder (HCM). The resulting MOs demonstrate that only the set of radial-MOs of the B27+ skeleton significantly interact with MOs of a stretched Sc2 dimer. This structure is representative of a new fruit can-type of shape in the family of doped boron clusters.

The adsorption, activation and possible dissociation of the glucose molecule on the magnetic [BN fullerene-B6]− system is performed by means of density functional theory calculations. Three models of magnetic nanocomposites were inspected: i) pristine BN fullerene, BN fullerene functionalized with a magnetic B6 cluster which generates two structures: ii) pyramidal (P) and iii) triangular (T). Chemical interactions of glucose appear for all these cases; however, for the BNF:B6(T)—glucose system, the interaction generates an effect of dissociation on glucose, due to the magnetic effects, since it has high spin multiplicity. The latter nanocomposite shows electronic behavior like-conductor and like-semi-conductor for the P and T geometries, respectively. Intrinsic magnetism associated to values of 1.0 magneton bohr (µB) for the pyramidal and 5.0 µB for the triangular structure, high polarity, and low-chemical reactivity are found for these systems. These interesting properties make these functionalized fullerenes a good option for being used as nano-vehicles for drug delivery. These quantum descriptors remain invariant when the [BN]−fullerene and [BNF:B6 (P) or (T)]− nanocomposites are interacting with the glucose molecule. According to the determined adsorption energy, chemisorption regimes occur in both the phases: gas and aqueous medium.

The influence of lithiation process on the HOMO–LUMO gap and the first hyperpolarizability values of corannulene (C20H10) and quadrannulene (C16H8) buckybowls are investigated using density functional theory (DFT) calculations. Lithiation is performed at the bridging position of the C–C bond of benzene rings of quadrannulene and corannulene. The HOMO–LUMO gap of lithiated buckybowls is reduced with respect to pristine ones. The results indicate that the lithiation process causes the remarkable enhancement of the first hyperpolarizability. The time-dependent density functional theory (TD-DFT) calculations are also performed to understand how lithiation affects the first hyperpolarizability values. The present results might be valuable for further theoretical and experimental studies on the electronic and nonlinear optical properties of buckybowl compounds.

The potential applicability of B 40 and Li@B 40 fullerenes as chemical sensors for NO 2 pollutant detection is investigated by employing DFT calculations. The results indicate that NO 2 molecule is remarkably chemisorbed on the surface of both B 40 and Li@B 40 fullerenes. It is found that electronic properties of B 40 and Li@B 40 fullerenes change after NO 2 chemisorption. Although the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies gap (HLG) of B 40 is considerably decreased after NO 2 chemisorption, the HLG of Li@B 40 are significantly enhanced after NO 2 adsorption. B 40 and Li@B 40 fullerenes are introduced as novel promising chemical sensor for NO 2 pollutant.

In this work, density functional theory (DFT) calculations are being made to investigate the interaction between the 5-fluorouracil (FU) anticancer drug with the bare and M−encapsulated (M = Na and Ca) all-boron B40 fullerenes. Our results reveal that the FU drug remarkably interacts with both bare and encapsulated fullerene. The electronic structure of the fullerenes is significantly affected via interaction with the FU drug molecule. The decrease of the energy gap of the stable complexes can be used as a chemical signal for determining the FU drug adsorption. The adsorption of six fluorouracil molecules on the top of the Na and Ca encapsulated B40 shows greater adsorption energy than bare fullerene in the gas and water phases. Also, the high dipole moments are found for the considered complexes in the water phase. Consequently, Na@B40 and Ca@B40 are introduced as promising innovative candidates for drug delivery of the Fu molecule due to their strong adsorption energies and great solubility in the polar medium. The results might open new windows in the nanomedicine domain.

This study focused on the theoretical viability of Ngn@C24N24 (Ng = Ne, Ar, Kr, Xe, and Rn; n = 1, 2) complexes using density functional theory at the computational level of ωB97X-D/def2-TZVP. Thermodynamic and kinetic stabilities of these complexes have been evaluated by calculating the interaction energy of Ng atoms encapsulated C24N24 cage ( Δ E i n t ), and the corresponding dissociation energy barrier ( Δ G ‡ ) , respectively. The obtained results predict that although these complexes are thermodynamically unstable compared to their dissociation into free Ng atoms and the bare C24N24 cage, but once formed, they are protected by the activation energy barrier of the corresponding dissociation process. Furthermore, natural population analysis (NPA) and topological analysis of the electron density have been employed to investigate the nature of Ng-Ng and Ng-cage interactions. The results demonstrate that these interactions are highly significant compared to similar cases in the free state; and the amounts of energy of the interaction gradually increases as the Ng atom becomes heavier. Surprisingly in the Kr2@C24N24 complex the Kr-Kr bond is somewhat covalent in nature relative to non-bonded interaction in Kr2 free dimer.

The electronic properties and NLO response of small LiBn (n = 4–11) nanoclusters are investigated by the MP2/6-311 + G(d) and CAM-B3LYP/6-311 + G(d) levels of theory. Pure boron clusters Bn (n = 5–12) are chosen as the starting point and the boron atom is replaced by Li atom. The results showed that the formation of some doped clusters is thermodynamically stable. The electronic properties of these clusters are strongly sensitive to Li doping. Moreover it is observed that the Li doping enhances the first hyperpolarizabilities of Bn nanoclusters. It is found that the lithiation of boron clusters is an efficient approach to enhance their NLO response and narrow their HOMO-LUMO gaps. The results might open new perspectives for further development of designing novel promising electro-optical boron-based nanomaterials.

The potential applicability of newly synthesized B36 nanosheet as a chemical sensor for formaldehyde (HCHO), acetaldehyde (CH3CHO) or propanal (CH3CH2CHO) pollutants detection is investigated by employing DFT calculations. The results indicate that although these pollutant molecules weakly interact with concave or convex sides of nanosheet, it remarkably adsorbed at the edge of B36 nanosheet. Indeed, the adsorption of one to six pollutant molecules at the edge of B36 nanosheet is considered to investigate adsorption capacity. The results reveal that the adsorption energies and electronic properties are affected by the number of adsorbed pollutant molecules. The B36 nanosheet is introduced as a chemical sensor for HCOH, CH3CHO or CH3CH2CHO detection due to producing an electrical signal which is sensitive to their concentration.

Interaction of fluorouracil, a conventional anticancer drug, with the B36 nanosheet is investigated systematically using the density functional theory (DFT) method. The results indicate that although fluorouracil weakly interacts with convex and concave sides of nanosheet, it is remarkably adsorbed at the edge of B36 nanosheet through its oxygen atoms. The interactions are also studied in terms of NBO charges and molecular electrostatic potential analysis. It is found that the interaction of this drug molecule with nanosheet significantly alters its electronic nature. The energy gap of the stable systems are reduced which could be applied as a chemical signal. Indeed, it is found that the adsorption of fluorouracil molecule at the edge of the B36 nanosheet is effective in aqueous medium. The relative high dipole moments are estimated for B36-FU systems, exhibiting that these systems could be solubilized or dispersed in polar mediums, like water. The obtained results introduce the B36 nanosheet as an efficient carrier for delivery of fluorouracil in nanomedicine domain.

The electro-optical features of functionalized sumanenes with BH, NH, O and S groups is studied theoretically. The effects of substitution on the sumanene CH 2 groups with hetero groups are studied using density functional theory computations. Thereafter the multilithiation effect of pristine and heterosubstituted sumanenes are studied to reveal the impact of these modifications on their electro-optical properties. The multilithiation of heterosubstituted sumanenes is an efficient approach to enhance their nonlinear optical response and narrow their highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies gaps. The results might open new perspectives for further development of designing novel electro-optical nanomaterials.

The binding of ozone molecule to the B36 bowl-shaped structure is scrutinized using the density functional theory (DFT) calculations. The interactions are investigated using B3LYP, B3LYP-D3, WB97XD, M06-2X and TPPSH methods. The ozone binding to the B36 structure is studied in terms of energetical, structural and electronic features. The results indicate that although ozone molecule weakly interacts with concave side of structure, it adds to the convex side and the edge of B36 structure. The ozone binding to the edge of B36 is more efficient than its convex side. The HOMO–LUMO gaps of the stable systems are reduced with respect to pure B36 sheet. This could be applied as a chemical signal. The obtained results introduce the B36 structure as an efficient ozone adsorbent.

A new silver complex [Ag(C4H6N2)2]2Cr2O7 (1) derived from Ag2[CrO4] and 2-methylimidazole has been synthesized and fully characterized by Single crystal X-ray diffraction, UV–Vis, FT-IR, elemental analysis, DFT and AIM calculations. The crystal structure of 1 shows that the discrete, ionic compound of [Ag(C4H6N2)2]2Cr2O7 consists of two [Ag(C4H6N2)2]+ cations bridged by a [Cr2O7]2− counter anion. In each of the [Ag(C4H6N2)2]+ complexes, the Ag center is coordinated by two N atoms from two distinct neutral monodentate 2-methylimidazole ligands in an almost linear geometry with Ag N distances between 2.068(4) A and 2.076(4) A and N Ag N bond angles of 179.4(2)° and 173.8(2)°. The N H⋯O and C H ⋯ O hydrogen bonds, π⋯π stacking, C H⋯ π and Ag⋯O interactions play an important role in the structural stabilization of the complex to generate a three-dimensional framework. The antibacterial activity and molecular docking studies of the free 2-methylimidazole ligand and the title complex show that these compounds have ability to inhibit the growth of the tested bacteria. A scanning probe microscopy (SPM) study of the treated bacteria was carried out to investigate the structural changes caused by the interactions between the complex and target bacteria. The interaction of the complex 1 with the E.coli DNA (E-DNA) has been studied by UV–Vis absorption, competitive DNA-binding studies with ethidium bromide by fluorescence and gel electrophoresis techniques. These experiments indicate that the complex interacts with DNA by intercalative binding.

Density functional theory calculations are carried out to investigate the interaction between the Nedaplatin anticancer drug and the bare and Li, Na encapsulated all-boron B40 fullerenes. The results indicate that this drug remarkably interacts with both bare and encapsulated fullerene. The electronic structure of the fullerenes significantly affected via interaction with drug molecule. The decrease of energy gap of the stable complexes is a chemical signal to determine drug adsorption. The adsorption of two NedaPt molecules on the top of the Li and Na encapsulated B40 shows greater adsorption energy than bare fullerene in the gas and water phases. The high dipole moments are found for the considered complexes in water phase. Consequently, Li@B40 and Na@B40 are introduced as promising innovative candidates for drug delivery of NedaPt molecule due to their strong adsorption energies and remarkable solubility in the polar medium. The results might open new windows in nanomedicine domain.

In this study, an attempt has been made to investigate alteration in electro-optical properties of bowl-shape B36 nanosheet due to interaction with one and two Li atoms. Our results reveal that the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gap of B36 nanosheet is decreased because of a high energy level which is formed under influence of interactions with Li atoms. Gigantic enhancement in the first hyperpolarizability (β0) of the studied nanosheet up to 4920.62 au is indicated owing to the effect of Li adsorption. The result of the present study may be eventuating to design and fabrication of a nanosheet with tunable electro-optical properties.

Density functional theory (DFT) calculations have been carried out to investigate the ozone addition process to both convex and concave sides of the pristine and functionalized sumanene structures using M06-2X/6-31 + G(d,p) level of theory. Although the ozone molecule only physisorbs on the concave side of the sumanene and its derivatives, it covalently adds to the convex side of them. The ozone addition to the convex side is investigated in details. It is found that the sumanene functionalization with BH and NH groups influence on the addition of ozone to sumanene by varying the energetical and electronic features. It is found that the BH-functionalization is slightly inducer of ozone addition while the NH-functionalization is modulator. Besides, the obtained HOMO-LUMO gap and electrophilicity values for these structures alter by ozone addition. The nature of the interactions is also scrutinized through Atoms in Molecules (AIM) theory. The results may provide novel insight for designing suitable materials for removal of O 3 pollutant.

Density functional theory (DFT) calculations have been carried out to study the electro-optical features of B 12 N 12 and B 16 N 16 nanoclusters by complexation via Li atom. The results reveal that the complexation process is energetically favorable. The electronic properties of these clusters are strongly sensitive to interaction with the Li atom. The HOMO–LUMO gaps of these nanoclusters are significantly narrowed due to the complexation via Li atom. Moreover it is observed that Li complexation enhances the first hyperpolarizabilities of B 12 N 12 and B 16 N 16 nanoclusters. The first hyperpolarizabilities remarkably increase in the range of 2975 to 130,837 a.u. Also the TD-DFT calculations are also performed to investigate the origin of first hyperpolarizabilities. To sum up, it is found that the Li atom complexation with these BN-clusters acts a key role in tuning their electronic and nonlinear optical properties. It seems that these systems could be introduced as promising innovative electro-optical BN-based materials.

The interaction of cyanogen molecule with Al 12 N 12 nanocage has been studied using density functional theory (DFT) at CAM-B3LYP/6-31+G(d) level. Geometric, electronic structure and natural bond orbitals (NBO) analysis display that adsorption of cyanogen onto exterior surface of Al 12 N 12 is physisorption with adsorption energy ( E ads ) equal to −55.36 kJ/mol. UV–vis study shows a high intensity peak in 388.9 nm due to interaction of gas with nanocage. It is expected that Al 12 N 12 will be used in designing novel materials for potential applications to detect toxic cyanogen molecule.

The structural, electronic, and nonlinear optical (NLO) properties of pristine dodecadehydrotribenzo[18]annulene ([18]DBA) functionalizing with the alkali metal atom (Li and Na), NH2 and NO2 functi...

Density functional theory (DFT) calculations have carried out to investigate the nonlinear optical response of the B 40 fullerene by interaction with the alkali metals (Li, Na, K). The results reveal that the interacted fullerenes are energetically favorable. The B 40 electronic properties are strongly sensitive to the interaction with the alkali metals. Furthermore, the adsorption of the alkali metals over the B 40 hexagonal ring remarkably enhances the first hyperpolarizability up to 23111.72 a.u. Therefore, the B 40 fullerene interacted with the alkali metals could be introduced as a promising innovative nonlinear optical boron-based nanomaterial.

The influence of increasing number and changing the sequence of nitrogen atoms on the local aromaticity of azacarbazole derivatives are investigated. The local aromatic characters of the considered compounds are probed using quantitative descriptors including the geometry-based (harmonic oscillator model of aromaticity (HOMA)), magnetic index (nucleus independent chemical shift (NICSs)) and electronic based index (fluctuation delocalization index (FLU)). The aromaticity of pyrrole-like ring of the studied compounds is also analyzed through AIM theory. Furthermore, the global aromaticity of the studied azacarbazole derivatives is scrutinized using the magnetic susceptibility and HOMA together with its EN and GEO components. The obtained results indicate that the aromatic characters of these compounds are not greatly sensitive to the increasing numbers of nitrogen atoms and their sequences.

The interaction between formaldehyde monomer (H 2 CO) as well as dimer ((H 2 CO) 2 ) and pristine B 12 N 12 nanocluster is investigated at B3LYP/6-311++G(d,p) level of theory. It is found that in contrary to the pristine boron nitride nanotube and nanosheet, formaldehyde adsorption induce considerable variation in the electronic properties of the B 12 N 12 nanocluster. Also it is shown that the pristine B 12 N 12 cluster could adsorb up to four monomer and three dimer of formaldehyde molecules in which the HOMO–LUMO gap decreased about 38–55%. Since the conductivity of the B 12 N 12 nanocluster changes by the adsorption of formaldehyde molecules, the presence of this toxic gas could be detected. The Bader theory of atoms in molecules (AIM) is also applied to analyze the interaction of formaldehyde with nanocluster. It is suggested pristine B 12 N 12 nanocluster could be a promising candidate for detecting formaldehyde molecule. The results indicate that B 12 N 12 may be a promising chemical sensor for detection of formaldehyde molecule.

Density functional theory (DFT) calculations using the PBE0-D3 functional and the 6–31 + G(d) basis set were carried out to determine the potential application of newly experimentally observed B40 fullerene for the anode electrode for Mg-ion batteries (MIBs). Calculated results suggest the bare B40 fullerene as a promising anode material with remarkable average open-circuit voltage of 5.5 V and storage capacity of 744 mAhg−1. Furthermore, it was found that the halides (F–, Cl–, and Br–) encapsulation inside B40 fullerene with both remarkable thermodynamic and kinetic stability can markedly enhance average open-circuit voltage up to 8.8 V. This value is remarkable compared with previous reports in the literature. Additionally, we re-calculated the average open-circuit voltage with the TPPSh, M06-2X, and B3LYP-D3 functionals along with the 6–311 + G(d) basis set. The results are similar to those values obtained at PBE0-D3/6–31 + G(d). The nature of Mg and Mg2+ interaction with bare and halides encapsulated B40 were also analyzed through the quantum theory of atoms in molecules (QTAM). The current results in this study might open new windows for the design of promising boron-based anode materials for MIBs.

DFT calculations were carried out to determine the potential application of C24N24 cavernous nitride fullerene for the anode electrode for (Li/Na/K/Mg/Ca)-ion batteries (MIBs). Calculated results suggest the C24N24 fullerene as a promising anode material for all these metal-ion batteries. Furthermore, all six cavities of C24N24 fullerene can be decorated by metals, and the storage capacities of 516 and 258 mAh g−1 are obtained for this fullerene. Consequently, both high cell voltages an storage capacity suggest the C24N24 fullerene as an appropriate anode material for alkali and alkali earth metal-ion batteries.

We present calculations based on Density Functional Theory of the structural stability and electronic properties of graphene-like nanosheets substitutional doping with dehydrogenated hydrocarbons (C5, C6, C7 and C8) and with a linear boron nitride molecule. The results reveal that these nanosheets show high-stability (pristine and doped) according to their cohesion energy and vibrational analysis. The nanosheet-dehydrogenated hydrocarbons systems: exhibit high polarity, semiconductor behavior, and low chemical potential. The BC61NH21 doped system possess the lowest-work function values. Furthermore, the proposed BC43NH15, BC52NH18, BC61NH21, BC70NH24 models can be used in electronic devices or sensing applications.

In this work, quantum chemical calculations have been performed on the ionic liquids based on imidazolium, pyridinium, and pyrrolidinium cations with the dicyanamide anion. The dispersion-corrected B3LYP exchange-correlation functional was used to optimize geometries. Enthalpies of formation were calculated at the high-level G3(MP2) theory by employing both the atomization energy and reaction enthalpy approaches. There exists a very good agreement between the predicted enthalpies of formation and available experimental values. For the first time, the enthalpies of formation have been predicted for 21 ion pairs with no available experimental data. The calculated enthalpies of formation are decreased with increasing alkyl chain length. Linear correlations were observed between enthalpy of formation and number of carbon atoms in the alkyl side-chain for all of the studied series of cations. Regardless of the cation type, the contribution of each CH2 group in the alkyl chain to the enthalpy of formation was also determined.

Density functional theory (DFT) calculations have been carried out to study the influence of alkali metals (Li, Na and K) encapsulation within the group III nitrides (B 12 N 12 , Al 12 N 12 and Ga 12 N 12 ) and the group IV carbides (C 24 , Si 12 C 12 and Ge 12 C 12 ) nanoclusters. The encapsulation of Li, Na and K atoms is found to narrow the HOMO–LUMO gaps of the considered clusters. The electronic properties of these clusters, especially the group III nitrides nanoclusters, are strongly sensitive to interaction with the alkali metals. Moreover it is observed that the encapsulation of alkali metals enhances the first hyperpolarizabilities of B 12 N 12 nanocluster. Surprisingly, due to the alkali metals encapsulation within B 12 N 12 nanocluster, the first hyperpolarizability values are remarkably increased to 8505.49 and 122,503.76 a.u. for Na@B 12 N 12 and K@B 12 N 12 , respectively. Also the TD-DFT calculations at both CAM-B3LYP/6-311+G(d) and PBE0/6-311+G(d) levels of theory are also performed to investigate the origin of first hyperpolarizabilities.

Adsorption of O 3 molecule on the surface of zigzag [5,0] single-walled AlNNT is investigated using DFT calculation for investigating their potential use as nanosensors. The O 3 is favorably chemisorbed on the AlNNT, with adsorption energy in the range −0.60 to −1.88 eV at B3LYP/6-31G* level. The adsorption of O 3 molecule onto the AlNNT would influence the electronic conductance and mechanical properties, which could use as a signal of gas sensor. It was found that this sensor has a high sensitivity by reducing E g from 4.16 eV in the pristine tube to 0.87 eV in the C configuration. Also this sensor has short recovery time due to the adsorption energy of O 3 molecule is not so large. So based on the above results, it is expected that AlNNT can act as a sensor to detect O 3 molecule.

The adsorption of CO molecule onto the outer surfaces of pristine and functionalized AlNNT and SiCNT is investigated using density functional theory. It is found that the CO molecule in C-down mode can be physisorbed onto the AlNNT and SiCNT. Moreover the adsorption of the CO molecule onto Cu-functionalized nanotubes is also considered. The adsorption energies rise to − 167.93 and − 193.34 kJ mol − 1 for AlNNT–Cu–CO and SiCNT–Cu–CO respectively. It is shown that the CO molecule in C-down mode strongly chemisorbed onto Cu-functionalized nanotubes with considerable amount of charge transfer from Cu-functionalized nanotubes to the CO molecule. In addition, results indicate that functionalized SiCNT nanotube with Cu atom is more favorable than functionalized AlNNT for CO adsorption. Natural bond orbital analysis indicates that the adsorption of CO molecule onto the Cu-functionalized nanotubes is influenced by the electronic conductance and mechanical properties, which could serve as a signal of gas sensor.

The newly found B40 is the first experimentally observed all-boron fullerene. The electronic (energy gap and work function) as well as electrical properties (first hyperpolarizabilities) of first row transition metals decorated B40 fullerene were explored using DFT calculations. The transition metals are decorated above the hexagonal and heptagonal rings of B40 fullerene. The findings demonstrate that transition metals can remarkably decrease the HOMO-LUMO energy gap and work function values. The obtained interaction energy values indicate that the transition metals interaction with heptagonal ring is much stronger than hexagonal one. The greatest amount of first hyperpolarizability ( β 0 ) belongs to the interaction cobalt metal with heptagonal ring of B40 with β 0 = 1.35 × 105 au. The conventional two-level model through TD-DFT calculations is considered to get better insights into how transition metals decoration influences on the first hyperpolarizability of B40 fullerene.