Zhengjing Jiang

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.

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 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.

Experimental and DFT studies on the vibrational and electronic spectra of 4,5-dihydro-6-methyl-4-[(E)-(3-pyridinylmethylene)amino]-1,2,4-triazin-3(2H)-one

Vibrational and electronic spectral measurements were made for 4,5-dihydro-6-methyl-4-[(E)-(3-pyridinylmethylene)amino]-1,2,4-triazin-3(2H)-one (pymetrozine). Optimized geometrical structure and harmonic vibrational frequencies were computed by ab initio RHF, B-based DFT methods (BLYP, BP86 and BPW91) and B3-based DFT methods (B3LYP, B3P86 and B3PW91) using 6-311++G(d,p) basis set. Complete assignments of the observed spectra were proposed. The absorption spectra of the compound were computed both in gas-phase and in C(2)H(5)OH 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. The MEP calculation indicates that the most possible site for electrophilic attack is H23 and the most possible sites for nucleophilic attack are N5 and O19.

Theoretical studies on vibrational spectra of some aluminum halides: Effect of theoretical methods and basis sets

The vibrational spectra of aluminum halides, AlX(3) (X=F, Cl, Br and I) and their dimers, Al(2)X(6), have been systematically investigated by ab initio restricted Hartree-Fock (RHF) and density functional B3LYP and B3P86 methods with LanL2DZ, SDD, CEP-31G and DGDZVP basis sets. The optimized geometries, calculated vibrational frequencies were evaluated via comparing with the experimental data. The vibrational frequencies, calculated by these methods with different basis sets, were compared to each other. The effect of the methods and the basis sets used on the calculated vibrational frequencies was discussed. The best fittings values between the calculated and the measured vibrational frequencies were achieved by B3LYP/DGDZVP theoretical level, with this method, the deviations are less than 2% for Al-X stretching vibrational modes in AlX(3) and less than 4% for Al-X stretching vibrational modes in Al(2)X(6). Some vibrational frequencies of Al(III) halides were predicted.

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 = 1.979 (8), Cu—O = 1.931 (6), Cu—Br = 2.514 (14) and Cu⋯Cu = 3.154 (6) ÅÅ. 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.

Hexakis(2-amino-4-methyl-pyridine-κN)dioxidohexa-μ(4)-sulfido-hexa-copper(I)divanadium(V).

The title compound, [Cu6V2O2S6(C6H8N2)6], is constructed from six CuS3N and two VOS3 distorted tetrahedra, forming an octanuclear V/S/Cu cluster with C i symmetry. The geometry around the V atoms is slightly distorted tetrahedral, while there are large distortions from ideal tetrahedral geometry for the Cu atoms. Adjacent metal–metal distances range from 2.693 (1) to 2.772 (10) Å, indicating weak metal–metal interactions in the cluster.

catena-Poly[[[aqua­tripyridine­cobalt(II)]-μ-5-amino-2,4,6-triiodoisophthalato-κ2O1:O3] pyridine solvate]

The reaction of cobalt(II) nitrate with 5-amino-2,4,6-triiodoisophthalic acid (ATPA) in pyridine solution leads to the formation of the title compound, {[Co(C8H2I3NO4)(C5H5N)3(H2O)]·C5H5N}n. The Co2+ ion is six-coordinated by three N atoms, one water O atom and two O atoms from two ATPA ligands to form a distorted octahedral geometry. The two carboxylate groups of ATPA act as bridging ligands connecting the CoII metal centers to form one-dimensional zigzag chains along the c axis, with Co—O distances in the range 2.104 (4)–2.135 (4) Å. The average Co—N distance is 2.171 Å. A classical O—H⋯N hydrogen bond is formed by the coordinating water molecule and the pyridine solvent molecule. The structure was refined from a racemically twinned crystal with a twin ratio of approximately 8:1.

catena-Poly[[dibromidomercury(II)]-μ-3-(1-methyl-pyrrolidin-2-yl)pyridine-κN:N'].

In the title polymeric complex, [HgBr2(C10H14N2)]n, each nicotine molecule is bonded to two adjacent Hg atoms, one through the pyrrolidine N atom and the other through the pyridine N atom, forming zigzag chains along [010]. The coordination around mercury is completed by two bromido ligands resulting in a distorted tetrahedral arrangement.