高分子化8-羟基喹啉锂的合成和发光特性的研究

以LiOH与5(2甲基丙烯酰乙氧基甲基)8羟基喹啉反应合成8羟基喹啉锂(Liq)配合物单体,并与甲基丙烯酸甲酯共聚合成含有高分化的8羟基喹啉锂.1HNMR、TGA、元素分析确定了单体的组成为Li(C9H5NO)CH2OCH2CH2OOCC(CH3)CH2·H2O.与聚甲基丙烯酸甲酯比较,共聚物热稳定性高.Liq含量<15wt%时共聚物能够溶于普通溶剂.紫外吸收、激发光谱、光致(PL)发光谱说明单体和共聚物的发光来自于Liq基团.单体和共聚物发蓝光.同时对共聚物的二甲基甲酰胺、二甲亚砜和四氯乙烷溶液制备的薄膜的光致发光光谱进行了比较,证明溶剂影响Liq基团上共轭电子的离域程度,对发光光谱有调节作用.     

Studies on Some Nickel(II) and Cobalt(II) Mixed Ligand Complexes of Arylsalicyl-Aldimine and Other Ligands

Several new mixed ligand complexes of Ni(II) and Co(II) of p-tolylsalicylaldimine (Sal-TH) or p-anisylsalicylaldimine (Sal-AH) with 8-hydroxyquinoline (HOx), benzohydroxamic acid (BH₂) or α-picoline (α-pic) have been synthesized. The complexes have the general formulae: [M(Sal-T)L],[M(Sal-A)L]⋅H₂O or [Ni(Sal-T)₂(α-pic)₂]⋅H₂O where M=Ni(II) or Co(II), Sal-T=p-tolylsalicylaldiminate, Sal-A=p-anisylsalicylaldiminate, L=8-hydroxyquinolinate or benzohydroxamate and α-pic=α-picoline. Analytical, conductivity and spectral data support a square planar structure for Co(II) complexes and octahedral structure for Ni(II) complexes. The thermal behaviour of the complexes has been studied by TG and DTG techniques. It was proposed that the decomposition of the complexed Schiff base takes place via a radical mechanism while for 8-hydroxyquinolinate or benzohydroxamate via proton transfer. Kinetic parameters of the thermal decomposition process have been computed by means of Coats-Redfern and Horowitz-Metzger methods. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and photophysical characterization of the free‐radical copolymerization of metaloquinolate‐pendant monomers with methyl methacrylate

A series of novel metaloquinolate [aluminum quinolate (Alq₃), zinc quinolate (Znq₂), and lithium quinolate (Liq)]‐containing copolymers were prepared. This is the first report of the synthesis of metaloquinolate‐containing polymers by free‐radical copolymerization. The structures of the metaloquinolate monomers and copolymers were characterized by ¹H NMR and Fourier transform infrared techniques. The differential scanning calorimetry and thermogravimetric analysis results showed that the copolymers were more thermally stable than the methyl methacrylate homopolymer. The copolymers (<25 wt % Alq₃, <20 wt % Znq₂, or <15 wt % Liq) could be dissolved in common solvents without crosslinking. The ultraviolet–visible absorption and photoluminescence (PL) emission properties of the copolymers were consistent with the literature data of metaloquinolate complexes. The PL efficiencies of the metaloquinolate‐containing copolymers with 25 wt % Alq₃, 20 wt % Znq₂, or 15 wt % Liq were 19.89, 13.24, and 11.82%, respectively. The experimental results indicated that these kinds of materials could be used for practical applications in organic light‐emitting diodes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 397–406, 2005     

Stochastic search of the quantum conformational space of small lithium and bimetallic lithium-sodium clusters

In this paper we report the results obtained by an implementation and application of the simulated annealing optimization procedure to the exploration of the conformational space of small neutral and charged lithium clusters (Li(n)(q), n = 5, 6, 7; q = 0, +/-1) and of the bimetallic lithium/sodium clusters (Li5Na) in their lowest spin states. Our methodology eliminates the structure guessing procedure in the process of generating cluster configurations. We evaluate the quantum energy, typically with the Hartree-Fock Hamiltonian, of randomly generated points in the conformational space and use a modified Metropolis test in the annealing algorithm to generate candidate structures for atomic clusters. The structures are further optimized by analytical methods (gradient following) at the M?ller-Plesset second order perturbation theory level (MP2), in conjunction with basis sets including polarization functions with and without diffuse functions. High accuracy ab initio energies at the coupled clusters level, with single, double, and triple substitutions from the Hartree-Fock determinant (CCSD(T)), on the MP2 geometries were calculated and used to establish the relative stability of the isomers within each potential energy surface. Various cluster properties were computed and compared to existing values in order to validate our methods. Our results show excellent agreement with previous experimental and theoretical reports. Even at these small sizes, evidence for 10 new structures never reported before for the lithium clusters and four new structures for the bimetallic clusters is presented.     

Cyclometallation reactions in complexes of the type Rh(oq)(CO)[P(o-BrC6F4)Ph2]. The molecular structure of F4)Ph2] (oq = 8-hydroxyquinolinate)

Cyclometallation occurs when a solution of the complex Rh(oq)(CO)(PCBr), (PCBr = 2-bromo-3,4,5,6-tetrafluorophenyldiphenylphosphine; OQ = 8-hydroxyquinolinate) in toluene is refluxed, giving ) (PC = P(C₆F₄)(C₆H₅)₂) and a dimeric compound, not yet completely characterized, formulated as Rh₂Br(oq)(PCBr)₂. ) was characterized by elemental analysis, by conductance measurements, and by ¹⁹F, ³¹P NMR and infrared spectroscopy. Its molecular structure was determined by single-crystal X-ray methods and refined by standard procedures to final agreement factors R and R_w of 0.067 and 0.060 for 5346 observed data. Lattice constants are 15.8494(6), 14.7188(5), 14.6675(5) Å and β 96.933(3)°, with monoclinic symmetry. The complex has a distorted octahedral geometry with a four atom metallocycle-ring (Rh---P---C---C) showing distorted angles of 69.8(2) and 84.8(2)° at Rh and P atoms, respectively. The analogous compound ), (5-moq = 5-methyl-8-hydroxyquinolinate), can be obtained by heating Rh(5-moq)(CO)(PCBr).     

Geometrical structures and dissociation channels of MP<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript><Superscript>+</Superscript> (M = Fe,Co or Ni; <Emphasis Type="Italic">n</Emphasis> = 2, 4, 6 or 8) binary cluster ions

A density functional theory study on the geometrical structures and dissociation channels of MP _n ⁺ (M = Fe, Co or Ni; n = 2, 4, 6 or 8) binary cluster ions has been performed. The tetrahedral P₄ structure and linear P₂ structure are found to be two relatively stable units in these ions. The lowest energy structures of MP _n ⁺ cluster ions are constructed by bonding a twofold or fourfold M atom with a P₄ or P₂ unit. The M–P bond is clearly weaker than the P–P bond. The most likely dissociation channel of the MP _n ⁺ cluster ions is the detachment of a P₄ or P₂ fragment. This conclusion is well consistent with the published experimental data and consistent with our previously reported theoretical study on the CrP _m ⁺ (m = 2, 4, 6 or 8) cluster ions.     

Experimental and theoretical studies on carbon-nitrogen clusters C2nN7-

C(2n)N7(-) cluster ions are produced by laser ablating on the K(3)[Fe(CN)6] sample. DFT calculations have been performed for these cluster anions. Various isomeric structures of these clusters are optimized and their energies are compared to find the most stable isomers. The most stable structure for C8N7(-) is similar to that of adenine by theoretical calculation, which is in agreement with the collision-induced dissociation (CID) experimental results. With the increasing even numbers of C atoms from 8 to 16, the N atoms in the double-ring structure are gradually substituted by C atoms from the six-membered ring to the five-membered ring. All these C(2n)N7(-) (n = 3-9) clusters exhibit planar aromatic characters. The energy difference and incremental binding energy analyses show that C(2n)N7(-) (n = 4-8) clusters are more stable than C6N7(-) and C18N7(-), which are consistent with the observed mass spectrum.     

QM/MM investigation of the degradation mechanism of the electron-transporting layer

The mechanism of charge transfer among tris(8-hydroxyquinolinate)aluminum (Alq₃) molecules in the electron-transporting layer (ETL) under amorphous conditions was theoretically investigated using both quantum mechanical/molecular mechanical (QM/MM) calculations and molecular dynamics (MD) simulations. The rate constant of the electron transfer was estimated for the equilibrated structure taken from the QM/MM MD simulations, based on the hopping model and Marcus theory. It was found that the coordination of a (LiF)₄ cluster in ETL drastically lowers the energy of the lowest unoccupied molecular orbital in the Alq₃ molecule. The small rate constant, namely the slow charge mobility, in ETL is believed to be causally related to the low-lying delocalized unoccupied molecular orbital of Alq₃ coordinated by the (LiF)₄ cluster. The results suggest that their interaction has a considerable influence on efficiency and is attributed in part to ETL degradation in organic light-emitting diodes.     

Surface structure and stability of MoSx model clusters

Density functional theory (DFT) computations have been carried out to study the structure and stability of MoSx clusters with the change of sulfur coverage at both Mo and S edges. DFT shows that adding sulfur to the Mo edge is always exothermic. However, deleting corner sulfur from the S edge is exothermic for 67 and 50% sulfur coverages, while deleting edge sulfur from the S edge is endothermic for 33 and 0% sulfur coverages. On the basis of the computed free energies along a wide range of H2S/H2 ratios, it is found that there are two stable structures with 33 and 50% sulfur coverages on the Mo edge by having 100% sulfur coverage on the S edge and one stable structure with 67% sulfur coverage on the S edge by having 0% sulfur coverage on the Mo edge. Under fully sulfiding atmosphere or at a very high H2S/H2 ratio, triangle MoSx structures with 100% sulfur coverage on the Mo edge are computed to be more stable than those with 100% sulfur coverage on the S edge, in agreement with the observation of scanning tunneling microscopy. In addition, the effects of cluster sizes on the surface structures are discussed.     

The crystal structures of a chiral aminoalkoxide cluster and its adduct with benzyllithium

The crystal structures of the chiral aminoalkoxide cluster (S)-2 and its unexpected adduct with benzyllithium (S)-3 have been determined. For compound (S)-2, a hexameric cyclic ring-ladder is observed in the solid state, which leads to an unshielded coordination site in a chiral pocket that is only accessible from one direction. The presence of (S)-2 leads to the deprotonation of toluene by n-butyllithium, giving benzyllithium. In contrast to earlier studies on lithium alkoxides, the resulting adduct (S)-3 between benzyllithium and (S)-2 is not formed by the exchange of alkoxy groups for alkanide units, as has been observed for a multitude of examples. Compound (S)-3 therefore represents a thus far unconsidered type of structure: the unshielded "top side" of the aminoalkoxide cluster (S)-2 capped by the lithium center of benzyllithium via three Li-O interactions.     

Microhydration of NO3(-): a theoretical study on structure, stability and IR spectra

A systematic study on the structure and stability of nitrate anion hydrated clusters, NO3(-) x n H2O (n = 1-8) are carried out by applying first principle electronic structure methods. Several possible initial structures are considered for each size cluster to locate equilibrium geometry by applying a correlated hybrid density functional with 6-311++G(d,p) basis function. Three different types of arrangements, namely, symmetrical double hydrogen bonding, single hydrogen bonding and inter-water hydrogen bonding are obtained in these hydrated clusters. A structure having inter-water hydrogen bonding is more stable compared to other arrangements. Surface structures are predicted to be more stable over interior structures. Up to five solvent H2O molecules can stay around solute NO3(-) anion in structures having an inter-water hydrogen-bonded cyclic network. A linear correlation is obtained for weighted average solvent stabilization energy with the size (n) of the hydrated cluster. Distinctly different shifts of IR bands are observed in these hydrated clusters for different kinds of bonding environments of O-H and N=O stretching modes compared to isolated H2O and NO3(-) anion. Weighted average IR spectra are calculated on the basis of statistical population of individual configurations of each size cluster at 150 K.     

Investigation of the extraction of some copper(II) chelates using isotope64Cu

The extraction of copper(II) 8-hydroxyquinolinate, 5,7-dichloro-8-hydroxyquinolinate and 2-thenoyltrifluoroacetonate was investigated and the stability constants and distribution constants of the complexes were determined. The dependence of thepH values for 50% extraction and of the distribution constants of the copper complexes on the dissociation constants and distribution constants of the corresponding agents are discussed.     

Structures and electronic properties of small FeB n (n=1-10) clusters

The geometries, stabilities, electronic properties, and magnetism of FeB(n) clusters up to n=10 are systematically studied with density functional theory. We find that our optimized structures of FeB(2), FeB(3), FeB(4), and FeB(5) clusters are more stable than those proposed in previous literature. The results show that it is favorable for the Fe atom to locate at the surface, not at the center of the cluster, and that FeB(4) and FeB(9) clusters exhibit high stability. For all the FeB(n) clusters studied, we find the charge transfer from Fe to B site and the coexistence of ionic and covalent bonding characteristics. The computed total magnetic moments of the lowest-energy structures oscillate with the cluster size and are quenched at n=4, 6, 8, and 10.     

Quantum chemistry study of H+(H2O)8: a global search for its isomers by the scaled hypersphere search method, and its thermal behavior

The structures of the protonated water cluster H+(H2O)8 have been globally explored by the scaled hypersphere search method. On the Hartree-Fock potential energy surface 174 isomers were found, among which 168 were computed to be minima at the B3LYP/6-31+G** level, and their energies were further refined at the level of MP2/6-311++G(3df,2p). The global minimum on the potential energy surface computed at the B3LYP/6-31+G** level shows a cagelike structure with the "Eigen" motif, while the lowest-free-energy isomer has a five-membered-ring structure at 170 K and a chain form at 273 K. The present results are well in line with previous experimental findings. In addition, the ADMP (atom-centered density matrix propagation) simulation indicates that the extra proton in the lowest-free-energy isomer (170 K), which has a five-membered ring and the "Zundel" feature, is often in an asymmetrical hydrogen bond.     

Structure of molybdenum and tungsten sulfide M(x)S(y)+ clusters: experiment and DFT calculations

A combination of experiment and density functional theory was used to investigate the energetics of CO adsorption onto several small M(x)S(y)(+) (M = Mo, W; x/y = 2/6, 3/7, 5/7, 6/8) clusters as a probe of their atomic and electronic structure. Experimentally, tandem mass spectrometry was used to measure the relative yields of M(x)S(y)(+)(CO)(n) cluster adducts formed by collisions between a beam of mass-selected M(x)S(y)(+) cluster ions and CO molecules in a high-pressure collision cell (hexapole ion guide). The most probable M(x)S(y)(+)(CO)(n) adducts observed are those with n < or = x, that is, only one CO molecule bound to each metal site. The notable exception is the M(5)S(7)(+) cluster, for which the n = 6 adduct is found to have nearly the same intensity as the n = x = 5 adduct. Density functional calculations were used to search for the lowest energy structures of the bare M(x)S(y)(+) clusters and to obtain their relative stability for sequential CO binding. The calculated trends in CO binding energies were then compared to the experimental adduct distributions for assigning the ground-state structures. In this way, it was possible to distinguish between two nearly isoenergetic ground-state isomers for the M(2)S(6)(+) and M(3)S(7)(+) clusters, as only one isomer gave a calculated CO stabilization energy trend that was consistent with the experimental data. Similar comparisons of predicted and observed CO adsorption trends also provide evidence for assigning the ground-state structures of the M(5)S(7)(+) and M(6)S(8)(+) clusters. The latter contain metallic cores with most of the sulfur atoms bonded along the edges or in the faces of the metal core structure. The n = 6 and 7 adducts of M(5)S(7)(+) are predicted to be more stable than the n = x = 5 adduct, but only the n = 6 adduct is observed experimentally. The DFT calculations show that the n = 7 adduct undergoes internal bond breaking whereas the n = 6 framework is stable, albeit highly distorted. For the M(6)S(8)(+) cluster, the calculations predict that the two lowest energy isomers can bind more than six CO molecules without fragmentation; however, the apparent binding energy drops significantly for adducts with n > 6. In general, the ability of these small M(x)S(y)(+) clusters to bind more CO molecules than the number of metal atoms is a balance between the gain in CO adsorption energy versus the strain introduced into the cluster structure caused by CO crowding, the consequences of which can be fragmentation of the M(x)S(y)(+)(CO)(n) cluster adduct (n > x).     

A DFT Study on the Structure and Properties of Cu/Cr2O3 Catalyst

Using DFT method, the stable adsorption configurations of Cu₄ cluster on Cr₂O₃ (0001) surface were investigated. The regular tetrahedron structure and the planar structures were considered as the initial adsorption configuration of Cu₄ cluster, respectively. The adsorption energies of the two structures were also calculated. The simulation result indicated that the adsorption energy of the regular tetrahedron structure was higher than that of the planar structure, and thus the regular tetrahedron structure was confirmed to be the stable adsorption configuration for Cu₄ cluster on Cr₂O₃ (0001) surface. Moreover, it was observed that the Cu₄ cluster showed the definite stable adsorption sites on Cr₂O₃ (0001) surface, namely 3‐fold O sites. During the adsorption process of Cu₄ cluster onto Cr₂O₃ (0001) surface, the Cu₄ cluster could bond with more Cr or O atoms on the surface, and the apparent charge transfer also occurred correspondingly. Meanwhile, the Cu₄ cluster and Cr₂O₃ (0001) surface would bond in the form of local polarization to enhance the stability of adsorption configuration.     

Density functional study of 8- and 11-vertex polyhedral borane structures: comparison with bare germanium clusters

Density functional theory (DFT) at the hybrid B3LYP level has been applied to the polyhedral boranes B(n)H(n)(z) (n = 8 and 11, z = -2, -4, and -6) for comparison with isoelectronic germanium clusters Ge(n)(z). The energy differences between the global minima and other higher energy borane structures are much larger relative to the case of the corresponding bare germanium clusters. Furthermore, for both B(8)H(8)(2-) and B(11)H(11)(2-), the lowest energy computed structures are the corresponding experimentally observed most spherical deltahedra predicted by the Wade-Mingos rules, namely the D(2)(d) bisdisphenoid and the C(2)(v) edge-coalesced icosahedron, respectively. Only in the case of B(8)H(8)(2-) is there a second structure close (+2.6 kcal/mol) to the D(2)(d) bisdisphenoid global minimum, namely the C(2)(v) bicapped trigonal prism corresponding to the "square" intermediate in a single diamond-square-diamond process that can lead to the experimentally observed room temperature fluxionality of B(8)H(8)(2-). Stable borane structures with 3-fold symmetry (e.g., D(3)(h), C(3)(v), etc.) are not found for boranes with 8- and 11-vertices, in contrast to the corresponding germanium clusters where stable structures derived from the D(3)(d) bicapped octahedron and D(3)(h) pentacapped trigonal prism are found for the 8- and 11-vertex systems, respectively. The lowest energy structures found for the electron-rich boranes B(8)H(8)(4-) and B(11)H(11)(4-) are nido polyhedra derived from a closo deltahedron by removal of a relatively high degree vertex, as predicted by the Wade-Mingos rules. They relate to isoelectronic species found experimentally, e.g., B(8)H(12) and R(4)C(4)B(4)H(4) for B(8)H(8)(4-) and C(2)B(9)H(11)(2-) for B(11)H(11)(4-). Three structures were found for B(11)H(11)(6-) with arachno type geometry having two open faces in accord with the Wade-Mingos rules.     

Investigations of the sodium and lithium D-lines in strong magnetic fields

Experimental and theoretical investigations of the splitting of the hyperfine structure of the sodium and lithium-D-lines in magnetic fields between 0 and 1 T were performed. In this magnetic field region the fine structure levelsJ=1/2 andJ=3/2 of the excited term² P begin to influence each other. In case of lithium crossings and anticrossings of hyperfine states stemming from different fine structure energy levelsJ=1/2 andJ=3/2 can be observed. The measurements were performed by laseratomic-beam spectroscopy in dependence on the applied external magnetic field strength. The experimental spectra were compared with computed spectra. Spectra were simulated by calculations using for the hyperfine hamiltonian two hyperfine constantsA andB in case of sodium and four hyperfine constantsa _c ,a _d ,a ₀ andb in case of lithium. Values for this constants could be derived by fitting the theoretical splittings to the experimental ones. For the first time theg _I — factor of sodium could be determined in a purely optical way.     

Red Phosphorescent Bis‐Cyclometalated Iridium Complexes with Fluorine‐, Phenyl‐, and Fluorophenyl‐Substituted 2‐Arylquinoline Ligands

Red phosphorescent iridium(III) complexes based on fluorine‐, phenyl‐, and fluorophenyl‐substituted 2‐arylquinoline ligands were designed and synthesized. To investigate their electrophosphorescent properties, devices were fabricated with the following structure: indium tin oxide (ITO)/4,4′,4′′‐tris[2‐naphthyl(phenyl)amino]triphenylamine (2‐TNATA)/4,4′‐bis[N‐(1‐naphthyl)‐N‐phenylamino]biphenyl (NPB)/4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl (CBP): 8 % iridium (III) complexes/bathocuproine (BCP)/tris(8‐hydroxyquinolinato)aluminum (Alq₃)/8‐hydroxyquinoline lithium (Liq)/Al. All devices, which use these materials showed efficient red emissions. In particular, a device exhibited a saturated red emission with a maximum luminance, external quantum efficiency, and luminous efficiency of 14200 cd m^?2, 8.44 %, and 6.58 cd A^?1 at 20 mA cm^?2, respectively. The CIE (x, y) coordinates of this device are (0.67, 0.33) at 12.0 V.     

Structure, stability, thermodynamic properties, and infrared spectra of the protonated water octamer H(+)(H2O)8

We investigated various two-dimensional (2D) and three-dimensional (3D) structures of H (+)(H 2O) 8, using density functional theory (DFT), Moller-Plesset second-order perturbation theory (MP2), and coupled cluster theory with single, double, and perturbative triple excitations (CCSD(T)). The 3D structure is more stable than the 2D structure at all levels of theory on the Born-Oppenheimer surface. With the zero-point energy (ZPE) correction, the predicted structure varies depending on the level of theory. The DFT employing Becke's three parameters with Lee-Yang-Parr functionals (B3LYP) favors the 2D structure. At the complete basis set (CBS) limit, the MP2 calculation favors the 3D structure by 0.29 kcal/mol, and the CCSD(T) calculation favors the 3D structure by 0.27 kcal/mol. It is thus expected that both 2D and 3D structures are nearly isoenergetic near 0 K. At 100 K, all the calculations show that the 2D structure is much more stable in free binding energy than the 3D structure. The DFT and MP2 vibrational spectra of the 2D structure are consistent with the experimental spectra. First-principles Car-Parrinello molecular dynamics (CPMD) simulations show that the 2D Zundel-type vibrational spectra are in good agreement with the experiment.