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Using the density functional theory methods, we effectively tune the second-order nonlinear optical (NLO) properties in some chalcone derivatives. Various unique push–pull configurations are used to efficiently enhance the intramolecular charge transfer process over the designed derivatives, which result in significantly larger amplitudes of the first hyperpolarizability as compared to their parent molecule. The ground state molecular geometries have been optimized using B3LYP/6-311G** level of theory. A variety of methods including B3LYP, CAM-B3LYP, PBE0, M06, BHandHLYP and MP2 are tested with 6-311G** basis set to calculate the first hyperpolarizability of parent system 1 . The results of M06 are found closer to highly correlated MP2 method, which has been selected to calculate static and frequency dependent first hyperpolarizability amplitudes of all selected systems. At M06/6-311G** level of theory, the permanent electronic dipole moment (μ tot ), polarizability (α 0 ) and static first hyperpolarizability (β tot ) amplitudes for parent system 1 are found to be 5.139 Debye, 274 a. u. and 24.22 × 10 −30 esu, respectively. These amplitudes have been significantly enhanced in designed derivatives 2 and 3 . More importantly, the (β tot ) amplitudes of systems 2 and 3 mount to 75.78 × 10 −30 and 128.51 × 10 −30 esu, respectively, which are about 3 times and 5 times larger than that of their parent system 1 . Additionally, we have extended the structure-NLO property relationship to several newly synthesized chalcone derivatives. Interestingly, the amplitudes of dynamic frequency dependent hyperpolarizability μβ ω (SHG) are also significantly larger having values of 366.72 × 10 −48 , 856.32 × 10 −48 and 1913.46 × 10 −48 esu for systems 1 – 3 , respectively, at 1400 nm of incident laser wavelength. The dispersion behavior over a wide range of change in wavelength has also been studied adopting a range of wavelength from 1907 to 544 nm. Thus, the present work realizes the potential of designed derivatives as efficient NLO-phores for modern NLO applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] New multifunctional materials have been modeled. [•] Effect of EDGs and EWGs was investigated on charge transfer and optical properties. [•] The intra-molecular charge transfer was observed from donor to acceptor moieties. [•] By DFT and TDDFT, different properties were computed. [•] The modeled compounds would be efficient semiconductor materials for multipurpose. [Copyright &y& Elsevier]

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). • A computational framework is proposed by tailoring nitrogen/boron atoms in dihydrodibenzo-pentacene. • The designed compounds showed great variation of optical and NLO properties. • Compound 4-BN has achieved the highest γ amplitude of 1858 × 10−36 esu owing to its tailored push-pull design. • Calculated open circuit voltage observed between 0.14 eV and 1.82 eV, and. • Computed light harvesting efficiency is found from 0.425 to 0.909 for newly designed compounds. [ABSTRACT FROM AUTHOR]

Owing to their excellent electrochemical properties, graphenes found applications in several fields ranging from semiconductors, solar cells, field effect transistors, and nanoscale electronic devices as well as in nonlinear optical (NLO) applications. The structural features, electro-optical, charge transport and nonlinear optical properties of the boron-doped graphene (BG) compound 1 were studied using density functional theory methods The BG compound comprises a central electron deficient site of boron atoms, which can serve as electron acceptor while terminal alkoxy groups as donors leading to powerful donor-π-acceptor (D-π-A) configuration. The experimental crystal structure was successfully reproduced by optimized ground state geometry at PBE0/6-311G* level of theory for isolated molecule. The experimental lattice parameters, geometries, crystal presentation and alignment of molecules in the unit cells as well as their packing orientation of BG compound 1 was also efficiently reproduced by applying periodic boundary conditions (PBC) at PBE level. The comprehensive intramolecular charge transfer (CT) was realized from terminal rings of the HOMO to the electron deficient sites of boron atoms of the LUMO. The nature of BG compound 1 might be more towards hole transport even though its hole reorganization energy is twice than that of the electron one due to the significant higher hole transfer integral values. The superior hole transfer integrals and intrinsic mobility values of the BG compound 1 might lead remarkable hole transport contender as compared to many other organic materials. The narrow band gap, density of states profile, dielectric function, uniform conductivity functions and noteworthy electronic as well as CT properties revealed that the BG compound 1 might be proficient optoelectronic contestant having intermolecular CT as well as intramolecular CT with optimal stability. A comparison of static third-order polarizability <γ> of BG compound 1 , as calculated in present investigation, was also performed with some standard NLO molecules as well as graphene nanoflakes. Moreover, longitudinal component γ zzzz of parent compound has been found 12 and 4 times larger than those of previously reported open-shell poly aromatic hydrocarbons (PAH). Interestingly, by increasing the donor ability, i.e., introduction of C 2 H 2 PhNH 2 groups in place of OC 4 H 9 groups (BG compound 3 ) at terminal positions boosts the <γ> amplitude ∼ 8 times than that of its parent BG compound 1 . [ABSTRACT FROM AUTHOR]

The present study explores a series of novel donor-π-acceptor (D-π-A) molecules containing 4,4′-dimethyldiphenylamine moiety as donor, 4,4′-dinitrodiphenylborane as acceptor while different π-bridges as efficient linkers between them, which comprises of (− HC CH −) n , (− Ph −) n and (− Ph ̶ HC CH −) n combinations for compounds in series 1, 2 and 3, respectively. Quantum chemical computations are applied to calculate the linear polarizability (α), first (β) and second (γ) hyperpolarizabilities. A comparative analysis is performed considering an increase of NLO polarizabilities as a function of different π-linkers. Among the investigated compounds, 3c shows the largest first and second hyperpolarizabilities of 1378 × 10−30 and 34971 × 10−36 esu, respectively. Interestingly, an increase in NLO polarizability is observed by modifying the π-conjugated bridges and the largest NLO polarizability is observed for series 3 possessing (Ph ̶ HC CH −) n π-linker which is found due to its lower transition energy and higher oscillator strengths. Furthermore, TD-DFT investigations, frontier molecular orbitals (FMOs) and electron density difference (EDD) maps analysis have shown a more efficient intramolecular charge transfer character from donor to acceptor moieties through (Ph ̶ HC CH −) n π-linkers. The density of states (DOS) maps are showing explicit contributions of electronic states from different fragments of a molecular system where the partial contributions of (Ph ̶ HC CH −) n π-linkers is seen significant in HOMO-LUMO orbitals of all the systems in series number 3. Thus, we believe that our study will highlight the importance of different D-π-A chromophores having variant types of π-conjugation cores as discussed in the present investigation. Schematic and graphical description of the designed D-π-A molecules. Image 1 • Three series of novel D-π-A molecules consisting of (HC=CH) n , (Ph) n and (Ph ̶ HC=CH) n combinations • The NLO polarizabilities are calculated using DFT methods. • All the designed series of compounds show reasonably larger NLO responses. • A structure-NLO property relationship is examined using TD-DFT, FMOs and EDD maps. [ABSTRACT FROM AUTHOR]