Density functional study of spectroscopy, electronic structure, linear and nonlinear optical properties of l-proline lithium chloride and l-proline lithium bromide monohydrate: For laser applications

AbstractUsing density functional theory (DFT), a systematic study of structure, bonding, vibration, excitation energies and non-linear optical properties has been carried out for noncentrosymmetric l-proline lithium chloride monohydrate and l-proline lithium bromide monohydrate for the first time. The calculated vibrational frequencies and the S0→S1 transition energy were compared with the earlier reported experimental results and found in good agreement. HOMO–LUMO energy gap was calculated by CIS, B3LYP and CISD using 6-31G(d,p), 3-21G, 6-31++G respectively and the obtained results are compared. For the calculation of excitation energies we used time dependent DFT (TDDFT). Both the molecules show the considerably lower dipole moment in excited state in comparison with the ground state. Mulliken charge and molecular electrostatic potential were studied. The first order hyperpolarizability for LPLCM and LPLBM are 2.15675×10−30esu and 3.78984×10−30esu respectively which are 5 and 10 times higher than prototype urea (0.3728×10−30esu) molecule. The global chemical reactivity descriptors were also calculated. The calculated results of polarizability, first and second hyperpolarizability confirm that these molecules are good non-linear optical materials and can be used for laser device fabrications

High-performance visible light photodetectors based on inorganic CZT and InCZT single crystals

Herein, the optoelectrical investigation of cadmium zinc telluride (CZT) and indium (In) doped CZT (InCZT) single crystals-based photodetectors have been demonstrated. The grown crystals were configured into photodetector devices and recorded the current-voltage (I-V) and current-time (I-t) characteristics under different illumination intensities. It has been observed that the photocurrent generation mechanism in both photodetector devices is dominantly driven by a photogating effect. The CZT photodetector exhibits stable and reversible device performances to 632 nm light, including a promotable responsivity of 0.38 AW−1, a high photoswitch ratio of 152, specific detectivity of 6.30 × 1011 Jones, and fast switching time (rise time of 210 ms and decay time of 150 ms). When doped with In, the responsivity of device increases to 0.50 AW−1, photoswitch ratio decrease to 10, specific detectivity decrease to 1.80 × 1011 Jones, rise time decrease to 140 ms and decay time increase to 200 ms. Moreover, these devices show a very high external quantum efficiency of 200% for CZT and 250% for InCZT. These results demonstrate that the CZT based crystals have great potential for visible light photodetector applicationsAuthors from KKU express their appreciation to the Deanship of Scientifc Research at King Khalid University for funding this work through research groups program under grant number R.G.P. 2/42/4

In Silico Identification of Potential Inhibitors of the SARS‑CoV‑2 Nucleocapsid Through Molecular Docking‑Based Drug Repurposing

SARS-CoV-2 is the virus responsible for the COVID-19 pandemic, and its effects on people worldwide continue to grow. Protein-targeted therapeutics are currently unavailable for this virus. As with other coronaviruses, the nucleocapsid (N) protein is the most conserved RNA-binding structural protein of SARS-CoV-2. The N protein is an appealing target because of its functional role in viral transcription and replication. Therefore, molecular docking method for structure-based drug design was used to investigate the binding energy and binding modes of various anti-N inhibitors in depth. The inhibitors selected were originally developed to target stress granules and other molecules involved in RNA biology, and were either FDA-approved or in the process of clinical trials for COVID-19. We aimed at targeting the N-terminal RNA binding domain (NTD) for molecular docking-based screening, on the basis of the first resolved crystal structure of SARS-CoV-2 N protein (PDB ID: 6M3M) and C-terminal domain (CTD) dimerization of the nucleocapsid phosphoprotein of SARS-COV-2 (PDB ID: 6WJI). Silmitasertib, nintedanib, ternatin, luteolin, and fedratinib were found to interact with RNA binding sites and to form a predicted protein interface with high binding energy. Similarly, silmitasertib, sirolimus-rapamycin, dovitinib, nintedanib, and fedratinib were found to interact with the SARS-CoV-2 N protein at its CTD dimerization sites, according to previous studies. In addition, we investigated an information gap regarding the relationships among the energetic landscape and stability and drug binding of the SARS-CoV-2 N NTD and CTD. Our in silico results clearly indicated that several tested drugs as potent putative inhibitors for COVID-19 therapeutics, thus indicating that they should be further validated as treatments to slow the spread of SARS-CoV-2

Investigation on the key features of L-Histidinium 2-nitrobenzoate (LH2NB) for optoelectronic applications: A comparative study

The current work is to highlight the fundamental acumen about the molecular structure, photophysical and static first hyperpolarizability (β) of L-Histidinium 2-nitrobenzoate (LH2NB) organic molecule for the first time. Hartree–Fock (HF) and density functional theory (DFT) has been applied using different functional at 6-31G∗∗ basis set for the first time. The strong correlation has been observed between experimental and theoretical vibrational spectra. TD-DFT method has been used at different levels of theory to study the UV–Visible spectra. The analysis of HOMO and LUMO was done to explain the charge interaction taking place within the molecule and the energy gap was evaluated. The value of dipole moment is found to be lower in excited state than ground state as calculated from all applied methods. The value of total static first hyperpolarizability was found to be 7.447 × 10−30 esu at B3LYP/6-31G∗∗ level of theory, which is about 20 times higher than urea molecule. The current results indicate that the studied molecule may be a decent applicant for opto-electronic applications

Exploring single-layered SnSe honeycomb polymorphs for optoelectronic and photovoltaic applications

Single-layered tin selenide that shares the same structure with phosphorene and possesses intriguing optoelectronic properties has received great interest as a two-dimensional material beyond graphene and phosphorene. Herein, we explore the optoelectronic response of the newly discovered stable honeycomb derivatives (such as α, β, γ, δ, and ɛ) of single-layered SnSe in the framework of density functional theory. The α, β, γ, and δ derivatives of a SnSe monolayer have been found to exhibit an indirect band gap, however, the dispersion of their band-gap edges demonstrates multiple direct band gaps at a relatively high energy. The ɛ-SnSe, however, features an intrinsic direct band gap at the high-symmetry Γ point. Their energy band gaps (0.53, 2.32, 1.52, 1.56, and 1.76 eV for α-, β-, γ-, δ-, and ɛ-SnSe, respectively), calculated at the level of the Tran-Blaha modified Becke-Johnson approach, mostly fall right in the visible range of the electromagnetic spectrum and are in good agreement with the available literature. The optical spectra of these two-dimensional (2D) SnSe polymorphs (besides β-SnSe) are highly anisotropic and possess strictly different optical band gaps along independent diagonal components. They show high absorption in the visible and UV ranges. Similarly, the reflectivity, refraction, and optical conductivities inherit strong anisotropy from the dielectric functions as well and are highly visible-UV polarized along the cartesian coordinates, showing them to be suitable for optical filters, polarizers, and shields against UV radiation. Our investigations suggest these single-layered SnSe allotropes as a promising 2D material for next-generation nanoscale optoelectronic and photovoltaic applications beyond graphene and phosphorene