DFT study on nonlinear optical properties of lithium-doped corannulene

Electronic, non-linear optical, optoelectronic, and thermodynamic properties of undoped and doped bis (ethylenedithio) tetraselenafulvalene (BETS) (C10H8S4Se4) molecule: first study using ab initio investigation

We have performed the ab initio calculation of the undoped and doped molecules bis (ethylenedithio) tetraselenafulvalene (BETS). Carbone (C) atoms have been substituted by Boron (B) to investigate their effects on the electronic structure and nonlinear optical, optoelectronic, and thermodynamic properties of BETS molecule. The RHF and hybrid density functional theories (WB97XD, B3PW91, and B3LYP) methods were applied, using the cc-pVDZ basis set. We found that the energy gap (Egap) of the doped molecules are respectively 2.476 eV and 2.569 eV for C₈B₂H₈S₄Se₄ and C₇B₃H₈S₄Se₄ with B3LYP/cc-pVDZ basis set, lower than one of the undoped molecule (3.316 eV). The significant increase values of polarizability (˂α˃) and first order hyperpolarizability (β) of the doped compounds, especially in C₈B₂H₈S₄Se₄ (< α >  = 4.5315 × 10^-23 esu, β = 22,672.27 × 10^-33 esu and < α >  = 4.518 × 10^-23 esu, β = 23,657.43 × 10^-33 esu respectively for B3LYP and B3PW91) compared to those of the undoped molecule (< α >  = 4.3602 × 10^-23 esu, β = 1290.38 × 10^-33 esu, and < α >  = 4.518 × 10^-23 esu) show that the new molecules have a good nonlinear optical property. Results suggest that these molecules doped with boron are a potential candidate as semiconductors compounds and nonlinear optical materials.

Deciphering the Role of Alkali Metals (Li, Na, K) Doping for Triggering Nonlinear Optical (NLO) Properties of T-Graphene Quantum Dots: Toward the Development of Giant NLO Response Materials

Nanoscale nonlinear optical (NLO) materials have received huge attention of the scientists in current decades because of their enormous applications in optics, electronics, and telecommunication. Different studies have been conducted to tune the nonlinear optical response of the nanomaterials. However, the role of alkali metal (Li, Na, K) doping on triggering the nonlinear optical response of nanomaterials by converting their centrosymmetric configuration into noncentrosymmetric configuration is rarely studied. Therefore, to find a novel of way of making NLO materials, we have employed density functional theory (DFT) calculations, which helped us to explore the effect of alkali metal (Li, Na, K) doping on the nonlinear optical response of tetragonal graphene quantum dots (TGQDs). Ten new complexes of alkali metal doped TGQDs are designed theoretically. The binding energy calculations revealed the stability of alkali metal doped TGQDs. The NLO responses of newly designed complexes are evaluated by their polarizability, first hyperpolarizability (β_o), and frequency dependent hyperpolarizabilities. The Li@r8a exhibited the highest first hyperpolarizability (β_o) value of 5.19 × 10⁵ au. All these complexes exhibited complete transparency in the UV region. The exceptionally high values of β_o of M@TGQDs are accredited to the generation of diffuse excess electrons, as indicated by NBO analysis and PDOS. NCI analysis is accomplished to examine the nature of bonding interactions among alkali metal atoms and TGQDs. Our results suggest alkali metal doped TGQD complexes as potential candidates for nanoscale NLO materials with sufficient stability and enhanced NLO response. This study will open new doors for making giant NLO response materials for modern hi-tech applications.

Designing and Encapsulation of Inorganic Al12N12 Nanoclusters with Be, Mg, and Ca Metals for Efficient Hydrogen Adsorption: A Step Forward Towards Hydrogen Storage Materials

Nanoclusters such as [Formula: see text][Formula: see text] have received increased attention due to their diverse applications in the fields of optoelectronics and energy storage. In this paper, we have investigated a series of alkaline earth metal (AEM)-encapsulated [Formula: see text][Formula: see text] nanoclusters for hydrogen adsorption. Thermodynamic adsorption parameters, optical and nonlinear optical properties were investigated using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. Encapsulation of AEMs (Be, Mg and Ca) is an effective strategy to improve the NLO reaction and thermodynamic and adsorption properties of [Formula: see text][Formula: see text] nanoclusters. The adsorption energies ranging from [Formula: see text]26.57[Formula: see text]kJ/mol to [Formula: see text]213.33[Formula: see text]kJ/mol for the three guests (Be, Mg and Ca) capsulated [Formula: see text][Formula: see text] nanoclusters are observed. The adsorption energy is affected by the size of the nanocage. Therefore, Ca- and Mg-encapsulated cages show higher values of adsorption energy. Overall, an increase in adsorption energy ([Formula: see text][Formula: see text]kJ/mol to [Formula: see text]91.06[Formula: see text]kJ/mol) is observed for (Be, Mg and Ca) encapsulated [Formula: see text][Formula: see text] nanoclusters compared to untreated [Formula: see text][Formula: see text] and H2-[Formula: see text][Formula: see text] cages. Moreover, adsorption of hydrogen on AEMs encapsulated in [Formula: see text][Formula: see text] leads to a decrease in the HOMO-LUMO energy gap with an enhancement of linear and nonlinear hyperpolarizability. All hydrogen-adsorbed AEMs [Formula: see text][Formula: see text] nanocages exhibit large [Formula: see text] and [Formula: see text] values, suggesting that these systems are potential candidates for optical materials. Various geometrical parameters such as frontier molecular orbitals (FMOs), partial density of states, global quantum descriptor of reactivity, natural bond orbital testing and molecular electrostatic strength analyses were performed to investigate the thermodynamic stability of all the studied systems. The results obtained confirmed that the designed systems are suitable for hydrogen storage. Therefore, we recommend that these systems be investigated for their hydrogen storage and optical properties.

Surface functionalization of twisted graphene C32H15 and C104H52 derivatives with alkalis and superalkalis for NLO response; a DFT study

Herein, we present the detailed comparative study on geometric, electronic, optical and non-linear optical response of alkalis and superalkalis doped twisted graphene. The results illustrate that alkali metals and superalkalis interact with the central ring of the twisted graphene through non-covalent interactions which demonstrate the stability of the resultant complexes. NBO charges indicate the transfer of electrons from dopant (alkali metal atoms and superalkalis) towards twisted graphene sheet. Superalkalis doped twisted graphene complexes exhibit higher first hyperpolarizability values compared to alkali metals analogues. Among superalkalis doped complexes, K₃O@C₁₀₄H₅₂ shows the highest β_o value of 1.68 × 10⁵ au. In frequency dependent first hyperpolarizability analysis, strong second harmonic generation (SHG) response of K₃O@C₃₂H₁₅ complex is observed at both selected resonance frequency values (532 nm and1064 nm) whereas EOPE value of K₃O@C₃₂H₁₅ complex shows higher induced response at 1064 nm wavelength. The static hyperpolarizability (β_o) further increases under the influence of applied electric field. Among all complexes, Li₃O@C₃₂H₁₅ graphene complex has the highest β_o value (1.40 × 10⁵ au) under applied electric field along x axis when sheet is in y-z plane. This analysis will be an important guideline for future studies on twisted graphene based NLO materials.

Exploration of adsorption behavior, electronic nature and NLO response of hydrogen adsorbed Alkali metals (Li, Na and K) encapsulated Al12N12 nanocages

Due to the increasing demand of Al[Formula: see text]N[Formula: see text] in optoelectronics and sensing materials, we intended to investigate the adsorption behavior, electronic nature and NLO response of hydrogen and different metals decorated Al[Formula: see text]N[Formula: see text] nanocages. Different systems are designed by hydrogen adsorption and encapsulation of metals (Li, Na and K) in Al[Formula: see text]N[Formula: see text]. Density functional theory at B3LYP functional with conjunction of 6-31G([Formula: see text], [Formula: see text] basis set is utilized in order to gain optimized geometries. Different calculations including linear and first-order hyperpolarizability are conducted at same level of theory. Instead of chemiosorption, a phyisosorption phenomenon is seen in all hydrogen adsorbed metal encapsulated Al[Formula: see text]N[Formula: see text] nanoclusters. The [Formula: see text] analysis confirmed the charge separation in hydrogen adsorbed metal encapsulated nanocages. Molecular electrostatic potential (MEP) analysis cleared the different charge sites in all the systems. Similarly, frontier molecular orbitals analysis corroborated the charge densities shifting upon hydrogen adsorption on metal encapsulated AlN nanocages. HOMO–LUMO band gaps suggest effective use of H2-M-AlN in sensing materials. Global indices of reactivity also endorsed that all hydrogen adsorbed metal encapsulated systems are better materials than pure Al[Formula: see text]N[Formula: see text] nanocage for sensing applications. Lastly, linear and first hyperpolarizability of H2-M-AlN nanocages are found to be greater than M-AlN and pure AlN nanocages. Results of these parameters recommend metal encapsulated nanocages as efficient contributors for the applications in hydrogen sensing and optoelectronic devices.

Deep analysis of N-cadherin/ADH-1 interaction: a computational survey

Due to the considerable role of N-cadherin in cancer metastasis, tumor growth, and progression, inhibition of this protein has been highly regarded in recent years. Although ADH-1 has been known as an appropriate inhibitor of N-cadherin in clinical trials, its chemical nature and binding mode with N-cadherin have not been precisely specified yet. Accordingly, in this study, quantum mechanics calculations were used to investigate the chemical nature of ADH-1. These calculations clarify the molecular properties of ADH-1 and determine its reactive sites. Based on the results, the oxygen atoms are suitable for electrophilic reactivity, while the hydrogen atoms that are connected to nitrogen atoms are the favorite sites for nucleophilic reactivity. The higher electronegativity of the oxygen atoms makes them the most reactive portions in this molecule. Molecular docking and molecular dynamics (MD) simulation have also been applied to specify the binding mode of ADH-1 with N-cadherin and determine the important residues of N-cadherin involving in the interaction with ADH-1. Moreover, the verified model by MD simulation has been studied to extract the free energy value and find driving forces. These calculations and molecular electrostatic potential map of ADH-1 indicated that hydrophobic and electrostatic interactions are almost equally involved in the implantation of ADH-1 in the N-cadherin binding site. The presented results not only enable a closer examination of N-cadherin in complex with ADH-1 molecule, but also are very beneficial in designing new inhibitors for N-cadherin and can help to save time and cost in this field.

Density functional theory study of structural and electronic properties of trans and cis structures of thiothixene as a nano-drug

The geometrical structure, electronic and optical properties, electronic absorption spectra, vibrational frequencies, natural charge distribution, MEP analysis and thermodynamic properties of the trans and cis structures of the drug thiothixene were investigated using density functional theory (DFT) and time-dependent DFT (TDDFT) methods with the B3LYP hybrid functional and 6-311 + G(d,p) basis set. The results of the calculations demonstrate that the cis structure of thiothixene has appropriate quantum properties that can act as an active medicine. The relative energies of trans and cis structures of thiothixene shows that the cis structure is more stable than the trans structure, with a small energy difference. TDDFT calculations show that the cis structure of thiothixene has the best absorption properties. The calculated NLO properties show that the NLO properties of the cis structure of thiothixene are higher than the trans structure, and the fact that the chemical hardness of the cis structure is lower than that of the trans structure that indicates that the reactivity and charge transfer of the cis isomer of thiothixene is higher than that of trans thiothixene. The molecular electrostatic potential (MEP) maps of both structures of thiothixene demonstrate that the oxygen atoms of the molecule are appropriate areas for electrophilic reactions. The vibrational frequencies of the two conformations of thiothixene demonstrate that both structures of thiothixene have almost similar modes of vibrations. The calculated thermodynamic parameters show that these quantities increase with enhancing temperature due to the enhancement of molecular vibrational intensities with temperature. Graphical abstract Trans/Cis isomerization of thiothixene drug.

NBO, conformational, NLO, HOMO-LUMO, NMR and electronic spectral study on 1-phenyl-1-propanol by quantum computational methods

In this study, FT-IR, FT-Raman, NMR and UV spectra of 1-phenyl-1-propanol, an intermediate of anti-depressant drug fluoxetine, has been investigated. The theoretical vibrational frequencies and optimized geometric parameters have been calculated by using HF and density functional theory with the hybrid methods B3LYP, B3PW91 and 6-311+G(d,p)/6-311++G(d,p) basis sets. The theoretical vibrational frequencies have been found in good agreement with the corresponding experimental data. (1)H and (13)C NMR spectra were recorded and chemical shifts of the molecule were compared to TMS by using the Gauge-Independent Atomic Orbital (GIAO) method. A study on the electronic and optical properties, absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies are performed using HF and DFT methods. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The local reactivity of the molecule has been studied using the Fukui function. NLO properties related to polarizability and hyperpolarizability are also discussed.