Quantum chemical framework for tailoring N/B doped phenalene derivatives to achieve high performance nonlinear optical materials.

Nonlinear optical (NLO) response materials are among the smartest materials of the era and are employed to modulate the phase and frequency of the laser. The present study presents a quantum chemical framework for tailoring nitrogen/boron doped derivatives of Dihydrodibenzo [de,op]pentacene through terminal and central core modifications. The derivatives of these compounds have been designed by introducing various π-conjugated connectors as well as B/N heteroatoms in the phenalene rings. Density functional theory (DFT) methods are used to optimize the ground state molecular geometries of designed compounds, represented as 1 to 4 (phenalene derivatives) and 1-BN to 4-BN (B/N doped phenalene derivatives) at the M06-2X/6-311G* level of theory. The highest value of 116.9 × 10-24 esu and 240.2 × 10-24 esu for isotropic and anisotropic linear polarizability is shown by compound 4. Among the designed compounds, 4-BN has achieved the highest γ amplitude of 1858 × 10-36 esu owing to its unique molecular structural design. Further analysis of electronic parameters, such as electron density difference (EDD) maps, the density of states, electrostatic potentials, transition density matrix (TDM) analysis, and frontier molecular orbitals analysis (FMOs), demonstrated the more effective intramolecular charge transfer (ICT) for the best compounds, resulting in a good NLO response. The compounds were also analyzed for their potential in photovoltaic applications based on factors such as open circuit voltage values determined to be between (0.14 eV and 1.82 eV), and light harvesting efficiency (0.425-0.909).

Chemically Modified Quinoidal Oligothiophenes for Enhanced Linear and Third-Order Nonlinear Optical Properties.

In the present investigation, quantum chemical calculations have been performed in a systematic way to explore the optoelectronic, charge transfer, and nonlinear optical (NLO) properties of different bis(dicyanomethylene) end-functionalized quinoidal oligothiophenes. The effect of different conformations (linking modes of thiophene rings) on conformational, optoelectronic, and NLO properties are studied from the best-performed dimer to octamer. The optical and NLO properties of all the selected systems (1-7) are calculated by means of density functional theory (DFT) methods. Among all the designed compounds, the largest linear isotropic (αiso) polarizability value of 603.1 × 10-24 esu is shown by compound 7 which is ∼12, ∼16, ∼9, ∼11, ∼10, and ∼4 times larger as compared to compounds 1-6, respectively. A relative investigation is performed considering the expansion in third-order NLO polarizability as a function of size and conformational modes. Among all the investigated systems, system 7 shows the highest value of static second hyperpolarizability ⟨γ⟩ with an amplitude of 7607 × 10-36 esu at the M06/6-311G** level of theory, which is ∼521, ∼505, ∼38, ∼884, ∼185, and ∼15 times more than that of compounds 1-6, respectively. The extensively larger ⟨γ⟩ amplitude of compound 7 with higher oscillator strength and lower transition energy indicates that NLO properties are remarkably dependent upon linking modes of thiophene rings and its chain length. Furthermore, to trace the origin of higher nonlinearities, TD-DFT calculations are also performed at the same TD-M06/6-311G** level of theory. Additionally, a comprehensive understanding of the effect of structure/property relationship on the NLO polarizabilities of these investigated quinoidal oligothiophenes is obtained through the inspection of Frontier molecular orbitals, the density of states (TDOS and PDOS), and molecular electrostatic potential diagrams including the transition density matrix. Hence, the current examination will not just feature the NLO capability of entitled compounds yet additionally incite the interest of experimentalists to adequately modify the structure of these oligothiophenes for efficient optical and NLO applications.

Metal doped fullerene complexes as promising drug delivery materials against COVID-19.

An outbreak of respiratory disorder caused by coronavirus has been named as coronavirus infection 2019 (COVID-19). To find a specific treatment against this disease researchers are at the frontline. To cure COVID-19, favipiravir (FPV) has been reported as an effective drug based on its high recovery rate. Among nanomaterials, fullerene C60 has achieved enormous attention as a drug delivery vehicle due to its good bioavailability and low toxicity. Hence, in this work, we have investigated the potential of metal-doped fullerene as a drug carrier, based on DFT calculations by using M06-2X functional and 6-31G(d) basis set in water media. In this research electronic parameters and adsorption energy of FPV on interaction with metal-doped (Cr, Fe, and Ni) fullerene is studied. The charge transfer between drug and doped fullerene has been studied through electrophilicity indexes. The structural and electronic properties are explored in terms of adsorption energy through frontier molecular orbital (FMO) and density of state (DOS). It is observed that doping of fullerene C60 with Cr, Fe, and Ni metals significantly enhances the drug delivery rate and provides numerous advantages including controlled drug release at specific target sites which minimize the generic collection in vivo and reduce the side effects. Thusly, it is suggested that our designed metal-doped complexes might be efficient candidates as drug delivery materials for COVID-19 infection. Supplementary Information: The online version contains supplementary material available at 10.1007/s11696-021-01815-4.