Guodong Tang

Synthesis, characteristic and theoretical investigation of the structure, electronic properties and second-order nonlinearity of salicylaldehyde Schiff base and their derivatives

A series of asymmetric donor-acceptor substituted salen-type Schiff-bases have been synthesized and their structures, electronic properties and second order nonlinearities were investigated by DFT methods. In order to verify the stable of these Schiff-base derivates, the IR spectrum of these Schiff-base derivates were calculated, the result showed that these compounds are stable. The results of TD-DFT calculation indicate that the derivatives with the electron-donating group (CH3, OCH3 or N(C2H5)2) have a red shift absorption compared to derivatives with the electron-withdrawing group (NO2). The analysis of MOS indicates that the CN group has contribution to the LUMO orbital while the groups of OCH3, N(C2H5)2 and NO2 have contribution to the HOMO orbital. OCH3, N(C2H5)2 as electron rich groups, made the derivates have a larger first static hyperpolarizability. However, the compound (II) with a NO2 substituent, also has a large first static hyperpolarizability. This is probably because of the special transition model, namely the values of two oscillator strength f (fHOMO-1-LUMO=0.405, fHOMO-LUMO=0.321) are almost equal. In order to understand the influence of the energy gap (ΔE) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (ΔE) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap is, the larger the first static hyperpolarizability is.

DFT and ab initio study on non-linear optical (NLO) properties of some organic complexes with different conjugate linker and substituent groups

A series of Schiff-bases chromophores containing imine or double C=C bond linkers between the donor and acceptor have been studied by first-principles calculations. The molecular structures, electronic properties and second order nonlinearities were investigated by DFT and ab initio methods. The optimized structural parameters of these Schiff-base derivates showed that these compounds are stable. The results of TD-DFT calculations indicate that the derivatives with the heterocyclic and imine linker have a red shift absorption compared to derivatives with the double C=C or N=N bonds. The analysis of the frontier molecular orbitals indicates that the CN group and the heterocycle linked by the CN or imine group has contribution to the LUMO orbital while the groups N(CH3)2 and the benzene ring linked by the double C=C or N=N bond have contribution to the HOMO orbital. The CN and the heterocyclic acceptors enable the derivatives to have a larger first static hyperpolarizability. However, the compounds 3-{4-[(4-Dimethylamino-phenylimino)-methyl]-pyridin-1-yl}-propanel-1-sulfonoperoxoic acid and 3-{4-[(4-Dimethylamino-phenylimino)-methyl]-quinolin-1-yl}propanel-1-sulfonoperoxoic acid with a substituent also have large first static hyperpolarizabilities due to the overwhelming contributions of electron density of the group to the HOMO orbital, that is, the HOMO orbital were constituted by the SO3− group only. In order to understand the influence of the energy gap (ΔE) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (ΔE) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap the larger the first static hyperpolarizability. The present study demonstrated that these compounds which have pure C=N double bond and heterocyclic substitution groups may have potential applications in the development of NLO materials.

Experimental and DFT studies on the vibrational and electronic spectra and NBO analysis of 2-amino-3-((E)-(9-p-tolyl-9H-carbazol-3-yl) methyleneamino) maleonitrile.

2-Amino-3-((E)-(9-p-tolyl-9H-carbazol-3-yl) methyleneamino) maleonitrile (ACMM) was synthesized and characterized by X-ray diffraction, FT-IR, FT-Raman and UV-Vis spectra. The X-ray diffraction study showed that ACMM has a Z-configuration, due to the intramolecular C18H18A⋯N2, N3H3A⋯N2 and C20H20A⋯N4 hydrogen bonds and intermolecular C10H10A⋯N4, N3H3B⋯N9 (2-x, 2-y, 2-z) and N3H8C⋯N4 (2-x, 1-y, 2-z) hydrogen bonds. The benzene ring including methyl is twisted from the mean plane of the carbazole group by 59.7(3)°. Vibrational spectra and electronic spectra measurements were made for the compound. Optimized geometrical structure and harmonic vibrational frequencies were computed with DFT (B3-based B3P86, B3LYP, B3PW91 and B-based BP86, BLYP, BPW91) methods and ab initio RHF method using 6-311++G(d, p) basis set. Assignments of the observed spectra were proposed. The equilibrium geometries computed by all of the methods were compared with X-ray diffraction results. The absorption spectra of the title compound were computed both in gas phase and in DMF solution using TD-B3LYP/6-311++G(d, p) and PCM-B3LYP/6-311++G(d, p) approaches, respectively. The calculated results provide a good description of positions of the bands maxima in the observed electronic spectrum. Temperature dependence of thermodynamic parameters in the range of 100-1000K were determined. The bond orbital occupancies, contribution from parent natural bond orbital (NBO), the natural atomic hybrids was calculated and discussed.

DFT studies on nonlinear optical properties of neutral nest-shaped heterothiometallic [MOS3Py5Cu3X] (M = Mo, W; X = F, Cl, Br, I) clusters

Theoretical calculations were carried out on some neutral nest-shaped heterothiometallic cluster compounds [MOS(3)Py(5)Cu(3)X] (M=Mo, W; X=F, Cl, Br, I) with the high first static hyperpolarizabilities beta values. The geometries of these cluster compounds were optimized by the restricted DFT method at B3LYP level with LanL2DZ base set without any constrains. In order to understand the relationship between the first static hyperpolarizabilities and the compositions of these clusters, the frontier orbital compositions and energy gaps between the HOMO and LUMO orbitals were calculated and analysed. In these clusters the HOMO orbitals are mainly composed of halogen atoms and the first static hyperpolarizability increases from F to I atom. The LUMO orbitals of clusters [MoOS(3)Py(5)Cu(3)X] are comprised of Mo, O and S atoms while the LUMO orbitals of clusters [WOS(3)Py(5)Cu(3)X] composed of W atom and pyridine ring. The energy gaps between the HOMO and LUMO orbitals of the clusters [MoOS(3)Py(5)Cu(3)X] are smaller than those of the clusters [WOS(3)Py(5)Cu(3)X]. As a result the first static hyperpolarizability values of the clusters [MoOS(3)Py(5)Cu(3)X] are higher than those of the clusters [WOS(3)Py(5)Cu(3)X].

Experimental and DFT studies on the vibrational and electronic spectra of 9-anthracenemethanol.

Vibrational spectral measurements were made for 9-anthracenemethanol. Optimized geometrical structure and harmonic vibration frequencies were computed based on ab initio and density functional theory B3LYP methods using 6-311G(**) and LANL2DZ basis sets. The equilibrium geometries got from all of the methods and basis were compared with X-ray diffraction results. The IR and UV-vis spectra of the title compound were computed using all of the methods and choose the most appropriate way to discuss. And the absorption spectra were calculated both in gas phase and in CH(3)CH(2)OH and CH(3)CN solution. The calculated results matched well with the experimental values. On the basis, the first excited state electronic transition energy has been calculated using time-dependent density functional theory.

Experimental and DFT studies on the vibrational and electronic spectra of 1,5-dimethyl-2-phenyl-4-[(pyridin-4-ylmethylene)-amino]-1,2-dihydro-pyrazol-3-one

Vibrational spectral measurements were made for 1,5-dimethyl-2-phenyl-4-[(pyridin-4-ylmethylene)-amino]-1,2-dihydro-pyrazol-3-one (DPPDP). Optimized geometrical structure and harmonic vibrational frequencies were computed by ab initio RHF and DFT (B-based BP86, BLYP, BPW91, B3-based B3P86, B3LYP, B3PW91 and O3-based O3LYP) methods using 6-311++G(d,p) basis set. Complete assignments of the observed spectra were proposed. The equilibrium geometries computed by all of the methods, were compared with X-ray diffraction results. The absorption spectra of the title compound were computed both in gas phase and in CH(3)CN solution using TD-B3LYP/6-311++G(d,p) and PCM-B3LYP/6-311++G(d,p) approaches and the calculated results provide a good description of positions of the two band maxima in the observed electronic spectrum.

μ(3)-Iodo-tri-μ(3)-sulfido-sulfidotris[tris-(4-methoxy-phen-yl)phosphine-κP]tri-copper(I)tungsten(VI) N,N-dimethyl-formide solvate.

A new W/S/Cu cluster, [Cu3WIS4(C21H21O3P)3]·C3H7NO, was formed by the reaction of ammonium tetrathiotungstate(VI), cuprous iodide and tris(4-methoxyphenyl)phosphine in N,N-dimethylformamide. The title compound exhibits a heavily distorted cubane-like skeleton in which the average Cu—I, Cu—S and W—μ3-S distances are 2.934, 2.302 and 2.249u2005Å, respectively. The W atom exhibits tetrahedral geometry, formed by three μ3-S and one terminal S atom; the W—S(terminal) bond length is 2.1426u2005(13)u2005Å. Each Cu atom is coordinated by one P atom from a tris(4-methoxyphenyl)phosphine (mop), two μ3-S and one μ3-I atom, forming a distorted tetrahedral coordination geometry. Some of the mop ligand methyl groups have large librations. Together with the three neutral mop ligands, the title compound is neutral; this contrasts with the all-halogen-coordinated Mo/S/Ag clusters with the same structure, which carry negative charge.

Synthesis, structural characterization and theoretical approach of the tri(2-(2,6-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) cobalt(II).

The crystal structure of a new coordination compound tri(2-(2,6-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) Co(II) complex ([Co(dcpip)3]Cl2) was measured with X-ray diffraction measurements. The compound is crystallizes triclinic, Pī space group. The ligand, 2-(2,6-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline(dcpip), binds to Co(II) ions with a bis-dentate mode, and each Co(II) ion with a distorted octahedral coordination geometry. The calculated interaction energies of Co(II) with coordination atoms N are between 101.7-206.5 kJ/mol and 115.3-230.9 kJ/mol for B3LYP/6-31+G(∗) and PBE1PBE/6-31+G(∗) theoretical methods, respectively. The experimental Fourier transform infrared spectrum was assigned. The calculated IR based on B3LYP/6-31+G(∗) and PBE1PBE/6-31+G(∗) methods were performed and compared with experimental results. The UV-Vis experimental spectrum of [Co(dcpip)3]Cl2 was measured in methanol solution. The calculated electronic spectrum was performed with TD/B3LYP and TD/PBE1PBE methods with 6-31+G(∗) basis set. The first and second order hyperpolarizability for the compound was calculated. The calculated values of γtot are -1.5551344 × 10(-33) esu for B3LYP method and -1.3323259 × 10(-33) esu for PBE1PBE method. The nature bond orbital analysis and temperature dependence of the thermodynamic properties were calculated with the same methods.

Hexa-μ2-bromido-μ4-oxo-tetra­kis[(nicotine)copper(II)]

In the title compound, hexa-μ2-bromido-μ4-oxo-tetrakis{[3-(1-methyl-2-pyrrolidinyl)pyridine-κN]copper(II)}, [Cu4Br6O(C10H14N2)4], the four Cu atoms are tetrahedrally arranged around the O atom at the cluster center. The Cu and coordinated N atoms lie along directions which correspond to four of the eight threefold axial directions of a regular octahedron. Each Cu atom lies at the center of a trigonal bipyramid, with the O atom and the pyridine N atom of a nicotine ligand in the axial positions and three Br atoms in the equatorial positions. Average bond distances are: Cu—N = 1.979u2005(8), Cu—O = 1.931u2005(6), Cu—Br = 2.514u2005(14) and Cu⋯Cu = 3.154u2005(6)u2005ÅÅ. The configuration of the nicotine ligands is that of the trans diastereomer. In addition, the crystal structure contains five intramolecular C—H⋯Br hydrogen bonds, which determine (or support) the orientation of the nicotine molecules relative to their three equatorial Br atoms. One of the nicotine molecules has two C—H⋯Br contacts, while the other three nicotine molecules show only one C—H⋯Br bond each. Two other intermolecular C—H⋯Br hydrogen bonds connect the complex molecules, forming ribbons which extend in the b- and c-axis directions.

catena-Poly[[diiodidomercury(II)]-μ-nicotine-κ2N:N′]

The title polymeric complex, [HgI2(C10H14N2)]n, was prepared from a solution of nicotine, mercury(II) iodide and 4-cyanopyridine in dimethylformamide. Each nicotine molecule is bonded to two Hg atoms, one through the pyrrolidine N atom and the other through the pyridine N atom, forming infinite zigzag polymeric chains. The coordination around mercury is completed by two iodide ligands, resulting in a distorted tetrahedral arrangement.