Spectroscopic investigation, FMOs and NLO analyses of Zn(II) and Ni(II) phenanthroline complexes: A DFT approach

Substituent and redox effects on the second-order NLO response of Ru(ii) complexes with polypyridine ligands: a theoretical study

Modifying ligands in four studied Ru(II) complexes have slight influence on their static first hyperpolarizabilities (βtot) values. However, the βtot values of complexes 1+/−–4+/− are all enhanced and the largest βtot value is observed for complex 4−.

Theoretical study by DFT of organometallic complexes based on metallocenes active in NLO

This study is based on the valuation of a few model molecules. The objective of this research is focused on linear optical (LO) and nonlinear optical (NLO) enhancement of five organometallic molecules based on different metallocenes. These molecules were subjected to several calculations by different long-range functionals CAM-B3LYP, LC-BLYP, LC-wPBE, wB97X, M11, and the following three Minnesota functionals: M06-2X and M08-HX in comparison with the MP2 approach. Hence, the CAM-B3LYP functional gave the closest NLO values to the MP2 method. Second, molecule 3A based on nickelocene recorded the highest static (β_tot) value which is 76.46 Χ 10^-30 esu and 4803.4 Χ 10^-30 esu under the laser wavelength λ = 532 nm. Third, intramolecular charge transfers (ICTs) of the molecules studied are all directed in both directions (donor to acceptor and vice versa). Finally, the specific solvent for molecules 2A and 3A is acetonitrile, and the maximum wavelengths obtained for the isolated or solvated molecule are all located in the near UV; the corresponding interval is between 250 and 395 nm. Graphical abstract.

Crystal Structure, Topological and Hirshfeld Surface Analysis of a Zn(II) Zwitterionic Schiff Base Complex Exhibiting Nonlinear Optical (NLO) Properties Using Z-Scan Technique

A mononuclear Zn(II) complex of (Zn(H2L) (CH3OH) Cl2) (1) has been synthesized by using a nonlinear optically active Zwitterionic Schiff base which is 4-((2-hydroxy-3-methoxybenzylidene) amino) benzoic acid (H2L). Complex 1 has been structurally analyzed by FTIR and UV spectroscopy, TGA, Powder-XRD and single crystal X-ray diffraction. X-Ray crystallographic studies revealed Zn(II) complex crystallizes in a P21/c space group and exists in a distorted trigonal bipyramidal geometry (τ = 0.68). The topological analysis of complex 1 showed that the underlying net is characterized by an unknown topological type and point symbol {342.468.510}, and multilevel analysis of complex packing as dimer gives a 18-c uninodal net with unknown topological type and point symbol {348.499.56}. The calculation results of a Hirshfeld surface analysis have been investigated to explore the H-bonding within the crystal. Third-order non-linear properties were also studied, which revealed that the lower input power (5.0 mM) for the material shows full transparency; however, it becomes opaque for higher input power. Such limiting behavior of complex 1 suggests its potential for instrumental protective devices against high laser illuminations.

Theoretical study of new push–pull molecules based on transition metals for NLO applications and determination of ICT mechanisms by DFT calculations

This study is based on the valuation of a few model molecules. The objective of this research is focussed on the nonlinear optical (NLO) improvement of four organometallic molecules and one organic molecule. These molecules have been subjected to several calculations by different functionals: CAM–B3LYP, LC–BLYP, LC–wPBE, wB97X, M11, M06–2X, M08–HX and M08–SO. These functionals gave three orders of classification of the [Formula: see text] parameters. The CAM–B3LYP functional recorded very good agreement between [Formula: see text] parameters and gaps ([Formula: see text]. Significant first hyperpolarizabilities ([Formula: see text] have been obtained around 880 * 10[Formula: see text][Formula: see text]esu. The mechanisms of intramolecular charge transfer (ICT) have shown energetic passages from donor groups to acceptors and vice versa. The substitution of metals influences the location of [Formula: see text] electrons at the level of the chromophores. Finally, the lengthening of the aromatic chains between the acceptor and donor groups shows significant NLO improvements. The first and second hyperpolarizabilities ([Formula: see text] and ([Formula: see text] for a chain of several benzene rings are of the order of 21,663.16 * 10[Formula: see text][Formula: see text]esu and 16,464.65 * 10[Formula: see text][Formula: see text]esu, respectively.

A theoretical study on cyclometalated iridium (III) complexes by using a density functional theory

Cyclometalated iridium (III) complexes (Ir1–Ir4) are calculated in detail with computational chemistry methods. The calculated structural parameters of Ir3 are compared with experimental values and a good fit is obtained. IR spectra are calculated at B3LYP/LANL2DZ/6-31G(d) level in the gases phase. Calculated 1H-NMR chemical shift values of the mentioned complexes are compared with the experimental data and all chemical shifts are assigned to the respective atoms. The quantum chemical parameters such as absolute hardness ([Formula: see text]), absolute softness ([Formula: see text]) electronegativity ([Formula: see text]), chemical potential ([Formula: see text]) and electronic charges ([Formula: see text]) are calculated and are associated with the experimental anti-cancer properties of the related complexes. Nonlinear optic properties of the Ir1–Ir4 were investigated with the average linear polarizability ([Formula: see text]), the anisotropy of the polarizability ([Formula: see text]), first hyperpolarizability ([Formula: see text]) values. Hole transfer ([Formula: see text]), electron transfer integrals ([Formula: see text]), hole reorganization energies ([Formula: see text]) and electron reorganization energies ([Formula: see text]) are examined. In addition, molecular docking study was performed. It was found that the molecular docking results are similar to the experimental anti-cancer trend.

Investigation of anticancer properties of caffeinated complexes via computational chemistry methods

Computational investigations were performed for 1,3,7-trimethylpurine-2,6-dione, 3,7-dimethylpurine-2,6-dione, their Ru(II) and Os(III) complexes. B3LYP/6-311++G(d,p)(LANL2DZ) level was used in numerical calculations. Geometric parameters, IR spectrum, ¹H-, ¹³C and ¹⁵N NMR spectrum were examined in detail. Additionally, contour diagram of frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) maps, MEP contour and some quantum chemical descriptors were used in the determination of reactivity rankings and active sites. The electron density on the surface was similar to each other in studied complexes. Quantum chemical descriptors were investigated and the anticancer activity of complexes were more than cisplatin and their ligands. Additionally, molecular docking calculations were performed in water between related complexes and a protein (ID: 3WZE). The most interact complex was found as Os complex. The interaction energy was calculated as 342.9kJ/mol.

Performance of Hybrid DFT Compared to MP2 Methods in Calculating Nonlinear Optical Properties of Divinylpyrene Derivative Molecules

A series of divinyl-pyrene derivatives of the form D-vinyl-pyrene-vinyl-A, in which D corresponds to an electron donor group and A to an electron acceptor group, were studied in this work. The first purpose was to determine the optimal HF % exchange as incorporated in a range of hybrid functionals (M06HF, M062X, M06L, CAM-B3LYP, PBE0, BMK, and B3LYP) capable to produce, reliably and as close as possible to those obtained from MP2 calculations, NLO parameters and, in particular, first-order static hyperpolarizabilities. The CAM-B3LYP functional was revealed to be the most suitable one. The pair N(CH₃)₂/NO₂ was then determined as the most efficient pair of groups in producing appreciable NLO responses. The effect of the substitution position on the pyrene moiety was also investigated, whereby aligning the two substituents involving the D and A groups in the direction of the dipole moment as in the (1,6 DVP) derivatives was shown to be most favorable for increasing the NLO parameters.