Binding affinity and permeation of X12Y12 nanoclusters for helium and neon

Rational Design, Stabilities and Nonlinear Optical Properties of Non-Conventional Transition Metalides; New Entry into Nonlinear Optical Materials

Electronic and nonlinear optical properties of endohedral metallofullerenes are presented. The endohedral metallofullerenes contain transition metal encapsulated in inorganic fullerenes X₁₂Y₁₂ (X = B, Al & Y = N, P). The endohedral metallofullerenes (endo-TM@X₁₂Y₁₂) possess quite interesting geometric and electronic properties, which are the function of the nature of the atom and the size of fullerene. NBO charge and frontier molecular orbital analyses reveal that the transition metal encapsulated Al₁₂N₁₂ fullerenes (endo-TM@Al₁₂N₁₂) are true metalides when the transition metals are Ni, Cu and Zn. Endo-Cr@Al₁₂N₁₂ and endo-Co@Al₁₂N₁₂ are at the borderline between metalides and electrides with predominantly electride characteristics. The other members of the series are excess electron systems, which offer interesting electronic and nonlinear optical properties. The diversity of nature possessed by endo-TM@Al₁₂N₁₂ is not prevalent for other fullerenes. Endo-TM@Al₁₂P₁₂ are true metalides when the transition metals are (Cr-Zn). HOMO-LUMO gaps (E_H-L) are reduced significantly for these endohedral metallofullerenes, with a maximum percent decrease in E_H-L of up to 70%. Many complexes show odd-even oscillating behavior for E_H-L and dipole moments. Odd electron species contain large dipole moments and small E_H-L, whereas even electron systems have the opposite behavior. Despite the decrease in E_H-L, these systems show high kinetic and thermodynamic stabilities. The encapsulation of transition metals is a highly exergonic process. These endo-TM@X₁₂Y₁₂ possess remarkable nonlinear optical response in which the first hyperpolarizability reaches up to 2.79 × 10⁵ au for endo-V@Al₁₂N₁₂. This study helps in the comparative analysis of the potential nonlinear optical responses of electrides, metalides and other excess electron systems. In general, the potential nonlinear optical response of electrides is higher than metalides but lower than those of simple excess electron compounds. The higher non-linear optical response and interesting electronic characteristics of endo-TM@Al₁₂N₁₂ complexes may be promising contenders for potential NLO applications.

Electrochemical sensing behavior of graphdiyne nanoflake towards uric acid: a quantum chemical approach

Though the gas sensing applications of graphdiyne have widely reported; however, the biosensing utility of graphdiyne needs to be explored. This study deals with the sensitivity of graphdiyne nanoflake (GDY) towards the uric acid (UA) within the density functional framework. The uric acid is allowed to interact with graphdiyne nanoflake from all the possible orientations. Based on these interacting geometries, the complexes are differentiated with naming, i.e., UA1@GDY, UA2@GDY, UA3@GDY, and UA4@GDY (Fig. 1). The essence of interface interactions of UA on GDY is derived by computing geometric, energetic, electronic, and optical properties. The adsorbing affinity of complexes is evaluated at ωB97XD/6-31 + G(d, p) level of theory. The stabilities of the complexes are quantified through the interaction energies (E_int) with reasonable accuracy. The calculated E_int of the UA1@GDY, UA2@GDY, UA3@GDY, and UA4@GDY complexes are - 31.13, - 25.87, - 20.59, and - 16.54 kcal/mol, respectively. In comparison with geometries, it is revealed that the higher stability of complexes is facilitated by π-π stacking. Other energetic analyses including symmetry adopted perturbation theory (SAPT), noncovalent interaction index (NCI), and quantum theory of atoms in molecule (QTAIM) provide the evidence of dominating dispersion energy in stabilizing the resultant complexes. The HOMO-LUMO energies, NBO charge transfer, and UV-vis analysis justify the higher electronic transition in UA1@GDY, plays a role of higher sensitivity of GDY towards the π-stacked geometries over all other possible interaction orientations. The present findings bestow the higher sensitivity of GDY towards uric acid via π-stacking interactions. Fig. 1 Optimized geometries (with interaction distances in Å) of UA@GDY complexes.

Unprecedented saturation limit achieved by inorganic polycationic cluster (Sb7Te8)5+ for light noble gases (He & Ne)

Among noble gases, Helium and Neon have smaller size, high ionization potential and low polarizability due to which these two gases exhibit weak binding affinities toward any surface. Bartlet's discovery and subsequent similar successful discoveries of stable complexes of noble gases opened new avenues for the storage of noble gases particularly on the new surfaces and their interactions for the storage of these gases. Here, we report the adsorption of light noble gases on polycationic clusters. Our current work not only investigates the interaction behavior of He and Ne with (Sb7Te8)⁵⁺ cluster but also explores the saturation limit of the cluster for He and Ne. Stability of various complexes of He and Ne with cationic surfaces is determined by the calculation of their interaction energies which reveal that the adsorption of single and multiple atoms of noble gases at faces of double cubic cluster is comparatively more favorable than at the bond lengths. Electronic properties such as HOMO-LUMO gaps show that complexes of He and Ne are more stable electronically than that of pure cluster, because HOMO-LUMO gap of complexes are higher than the bare polycationic cluster. NCI analysis of iso-surfaces and RDG maps confirms the presence of van der Waals forces between light noble gases and polycationic clusters. Saturation studies reveal that cluster can adsorb eleven He and/or ten Ne atoms with no or minimum distortion in the geometry of cluster. The results showed that Ne has greater tendency to interact with polycationic clusters due to the large electronic cloud and polarizability value than He.

Outstanding Performance of Transition-Metal-Decorated Single-Layer Graphene-like BC6N Nanosheets for Disease Biomarker Detection in Human Breath

In the present work, we report highly sensitive and selective nanosensors constructed with metal-decorated graphene-like BC6N employing nonequilibrium Green's function (NEGF) formalism combined by density functional theory (DFT) toward multiple inorganic and sulfur-containing gas molecules (NO, NO2, NH3, CO, CO2, H2S, and SO2) as disease biomarkers from human breath. Monolayer sheets of pristine BC6N and Pd-decorated BC6N were evaluated for their gas adsorption properties, electronic property changes, sensitivity, and selectivity toward disease biomarkers. The pristine BC6N nanosheets exhibited sharp drops in the bandgap when interacted with gases such as NO2 while barely affected by other gases. However, the nanosecond recovery time and low adsorption energies limit the gas sensing applications of the pristine BC6N sheet. On the other hand, the Pd-decorated BC6N-based sensor underwent a semiconductor to metal transition upon the adsorption of NO x gas molecules. The conductance change of the sensor's material in terms of I-V characteristics revealed that the Pd-decorated BC6N sensor is highly sensitive (98.6-134%) and selective (12.3-74.4 times) toward NO x gas molecules with a recovery time of 270 s under UV radiation at 498 K while weakly interacting with interfering gases in exhaled breath such as CO2 and H2O. The gas adsorption behavior suggests that metal-decorated BC6N sensors are excellent candidates for analyzing pulmonary disease and cardiovascular biomarkers, among other ailments of the stomach, kidney, and intestine.

Efficient Cu Decorated Inorganic B12P12 Nanoclusters for Sensing Toxic COCl2 Gas: A Detailed DFT Study

Gas sensing materials have been widely explored recently owing to their versatile environmental and agriculture monitoring applications. Phosgene (COCl2) is a toxic and harmful gas, therefore, a reliable and sensitive technique is required for monitoring its quantity in the atmosphere. In this study, pure as well as copper decorated B[Formula: see text]P[Formula: see text](Cu-BP) nanoclusters were analyzed using DFT method to investigate their specific potential for phosgene gas adsorption. Cu interaction resulted in three optimized geometries S1, S2 and S3 with interaction energies of [Formula: see text]234.52[Formula: see text]kJ/mol, [Formula: see text]214.59[Formula: see text]kJ/mol and [Formula: see text]266.45[Formula: see text]kJ/mol, respectively. In all these three cases, the COCl2 prefers to interact at the top of the cage. The phosgene molecule (COCl2) interacts with bare nanocage at a distance of 3.22[Formula: see text]Å with interaction energy of [Formula: see text]6.22[Formula: see text]kJ/mol, while the observed interaction energies of phosgene at Cu decorated B[Formula: see text]P[Formula: see text] are [Formula: see text]76.90[Formula: see text]kJ/mol, [Formula: see text]119.03[Formula: see text]kJ/mol and [Formula: see text]29.60[Formula: see text]kJ/mol, respectively. To observe the variations in electronic structure, fermi level, molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs), natural bonding orbital ([Formula: see text]), softness, hardness, chemical potential and electrophilicity are calculated before and after phosgene adsorption. Energy gap reduce significantly after phosgene adsorption from 2.31[Formula: see text]eV, 2.05[Formula: see text]eV and 2.46[Formula: see text]eV to 1.54[Formula: see text]eV, 1.57[Formula: see text]eV and 2.45[Formula: see text]eV, respectively. Results of all analysis suggested that decoration of Cu significantly enhanced the adsorption power of B[Formula: see text]P[Formula: see text] nan-cluster for COCl2 molecule. Therefore, the Cu-decorated B[Formula: see text]P[Formula: see text] nanocages are considered as potential candidates for application in COCl2 sensors.

Permeation of second row neutral elements through Al12P12 and B12P12 nanocages; a first-principles study

Both exohedral and endohedral complexes of second row elements doped X₁₂Y₁₂ (X = B, Al and Y = P) nano-cages are evaluated for thermodynamic stabilities, electronic properties and kinetic barriers. Interaction energies are calculated to deeply perceive the stability of these complexes. Further, interconversion of exohedral and endohedral complexes is explored through an unprecedented approach, where 2nd row elements translate into nano-cages through boundary crossing. Subsequently, the kinetic barriers for encapsulation and decapsulation are also investigated through PES scanning of all elements by passing through hexagon of nano-cages. Systematic investigations revealed that due to larger diameter, AlP nanocage exhibits low encapsulation barriers in comparison to BP nano-cage. Such as; the encapsulation barrier of F@AlP (7.57 kcal mol^-1) is lower than that of F@BP (129.78 kcal mol^-1). Moreover, distortion of nano-cages due to translation of elements is also estimated by distortion energies. Large distortion energies of 113.81/118.39 kcal mol^-1 are noticed for exo-B@AlP/exo-C@BP complexes. In addition, the electronic properties for all the complexes are probed and depicted that the endohedral doping have remarkable influence on the electronic properties of the nanocage in comparison to exohedral doping. NBO charge analysis shows that Be metal delivers charges of 0.08 |e|/0.03 |e| to the AlP/BP nanocage, causing the later more electron rich. Contrary to Be, all other doped atoms show negative charges.

Confinement Effects of a Noble Gas Dimer Inside a Fullerene Cage: Can It Be Used as an Acceptor in a DSSC?

A detailed density functional theory investigation of He₂-encapsulated fullerene C₃₆ and C₄₀ has been presented here. When confinement takes place, He-He bond length shortens and a non-covalent type of interaction exists between two He atoms. Energy decomposition analysis shows that though an attractive interaction exists in free He₂, when it is confined inside the fullerenes, repulsive interaction is observed due to the presence of dominant repulsive energy term. Fullerene C₄₀, with greater size, makes the incorporation of He₂ much easier than C₃₆ as confirmed from the study of boundary crossing barrier. In addition, we have studied the possibility of using He₂-incorporated fullerene as acceptor material in dye-sensitized solar cell (DSSC). Based on the highest energy gap, He₂@C₄₀ and bare C₄₀ fullerenes are chosen for this purpose. Dye constructed with He₂@C₄₀ as an acceptor has the highest light-harvesting efficiency and correspondingly will possess the maximum short circuit current as compared to pure C₄₀ acceptor.

Designing Novel Zn-Decorated Inorganic B12P12 Nanoclusters with Promising Electronic Properties: A Step Forward toward Efficient CO2 Sensing Materials

Gas sensing materials have been widely explored recently owing to their versatile environmental and agriculture monitoring applications. The present study advocates the electronic response of Zn-decorated inorganic B12P12 nanoclusters to CO2 gas. Herein, a series of systems CO2-Zn-B12P12 (E1-E4) are designed by adsorption of CO2 on Zn-decorated B12P12 nanoclusters, and their electronic properties are explored by density functional theory. Initially, placement of Zn on B12P12 delivers four geometries named as D1-D4, with adsorption energy values of -57.12, -22.94, -21.03, and -14.07 kJ/mol, respectively, and CO2 adsorption on a pure B12P12 nanocage delivers one geometry with an adsorption energy of -4.88 kJ/mol. However, the interaction of CO2 with D1-D4 systems confers four geometries named as E1 (E ad = -75.12 kJ/mol), E2 (E ad = -25.89 kJ/mol), E3 (E ad = -42.43 kJ/mol), and E4 (E ad = -28.73 kJ/mol). Various electronic parameters such as dipole moment, molecular electrostatic potential analysis, frontier molecular orbital analysis, Q NBO, global descriptor of reactivity, and density of states are also estimated in order to understand the unique interaction mechanism. The results of these analyses suggested that Zn decoration on B12P12 significantly favors CO2 gas adsorption, and a maximum charge separation is also noted when CO2 is adsorbed on the Zn-B12P12 nanocages. Therefore, the Zn-decorated B12P12 nanocages are considered as potential candidates for application in CO2 sensors.

Adsorption of Phosgene Gas on Pristine and Copper-Decorated B12N12 Nanocages: A Comparative DFT Study

Nanostructured gas sensors find diverse applications in environmental and agricultural monitoring. Herein, adsorption of phosgene (COCl₂) on pure and copper-decorated B₁₂N₁₂ (Cu-BN) is analyzed through density functional theory (DFT) calculations. Adsorption of copper on B₁₂N₁₂ results in two optimized geometries, named Cu@b₆₆ and Cu@b₆₄, with adsorption energies of -193.81 and -198.45 kJ/mol, respectively. The adsorption/interaction energies of COCl₂ on pure BN nanocages are -9.30, -6.90, and -3.70 kJ/mol in G1, G2, and G3 geometries, respectively, whereas the interaction energies of COCl₂ on copper-decorated BN are -1.66 and -16.95 kJ/mol for B1 and B2, respectively. To examine the changes in the properties of pure and Cu-BN nanocages, geometric parameters, dipole moment, Q _NBO, frontier molecular orbitals, and partial density of states (PDOS) are analyzed to comprehensively illustrate the interaction mechanism. The results of these parameters reveal that COCl₂ binds more strongly onto copper-doped BN nanocages. Moreover, a higher charge separation is observed in COCl₂-Cu-BN geometries as compared to copper-decorated BN geometries. Therefore, these nanocages may be considered as potential candidates for application in phosgene sensors.

Zinc-Doped Boron Phosphide Nanocluster as Efficient Sensor for SO2

Adsorption of SO2 on pure B12P12 and Zn-doped B12P12 is investigated through density functional theory methods. Zn adsorption on BP delivers four optimized geometries: B-Top, P-top, b64, and ring-enlarged geometry with adsorption energies of −57.12 kJ/mol, −14.50 kJ/mol, −22.94 kJ/mol, and −14.83 kJ/mol, respectively. The adsorption energy of SO2 on pristine boron phosphide is −14.92 kJ/mol. Interaction of SO2 with Zn-doped boron phosphide gives four different geometries with adsorption energies of −69.76 kJ/mol, −9.82 kJ/mol, −104.92 kJ/mol, and −41.87 kJ/mol. Geometric parameters such as dipole moment, QNBO, frontier molecular orbital analysis, PDOS, and global indices of reactivity are performed to visualize the changes in electronic properties of B12P12 after Zn and SO2 adsorption.

Density functional theory study of palladium cluster adsorption on a graphene support

The geometric, thermodynamic and electronic properties of Pd–graphene nanocomposites are comprehensively studied through quantum mechanical methods. Geometries of these clusters are optimized with the well-calibrated Minnesota functional M06-2X. The adsorption energies calculated at the M06-2X/LANL2DZ level show better agreement with those calculated from MP2/ANO-RCC-VDZP. Two different representative models for graphene, coronene and hexabenzocoronene, are used. The adsorption energies analysis reveals that the interaction energies increase with the size of the adsorbed cluster. However, for Pd_n/hexabenzocoronene, the interaction energies show a sudden drop at Pd₈/hexabenzocoronene. The difference in behavior between the interaction energies of Pd_n/hexabenzocoronene and Pd_n/coronene is attributed to the edge effect present in coronene. The electronic properties, including highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), Fermi level, molecular electrostatic potential (MEP), dipole moment, vertical ionization potential (VIP), vertical electron affinity (VEA), chemical hardness (η), softness (S) and chemical potential (μ) are studied. The VIP and VEA reveal that Pd_n/coronene clusters are stable in nature with the least reactivity. The HOMO–LUMO energy gaps are reduced with the increase in cluster size. The electronic properties show irregular trends, where the most favorable electronic properties are obtained for Pd₇/coronene and Pd₁₀/coronene.

The geometric, thermodynamic and electronic properties of Pd–graphene nanocomposites are comprehensively studied through quantum mechanical methods.

A theoretical study of the geometries, and electronic and surface properties of sphere-like (SiB)2n (n = 6–27, 30) functional nanomaterials

The geometries and electronic properties of (SiB)_2n (n = 6–27, 30) clusters are systematically investigated based on the gradient corrected Perdew–Burke–Ernzerhof exchange–correlation functional.

Transition metal doping: a new and effective approach for remarkably high nonlinear optical response in aluminum nitride nanocages

NLO response of early transition metal (Sc)-doped aluminum nitride nanocages is comparable to those of their alkali-metal-doped analogues.