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1.
The dipole moments μ, static polarizabilities , and first hyperpolarizabilities β
vec of benzothiazole based push–pull chromophores have been theoretically investigated by means of SCF-HF and DFT (B3LYP, B3PW91) methods with cc-pVDZ basis sets at geometries optimized with 3-21G basis sets. The main attention has been paid to hyperpolarizability β
vec as a microscopic quantity directly linked with the nonlinear optical (NLO) response of materials with the aim to choose the most suitable candidate(s) for NLO materials from the set of 24 molecules. The 4-dimethylamino-4′-nitrostilbene (DANS) has also been included as a reference compound. The influence of various structural modifications of benzothiazole containing chromophores on μ,, and β
vec has been studied. These modifications involve the variation in unsaturated chain length connecting the aromatic units, different positions of electron withdrawing NO2 and CN group attached to four possible positions in benzothiazole fragment, addition of the second NO2 group, and the replacement of benzene by five-membered heteroaromatic rings (pyrrole, furan, thiophene) at N(CH3)2 site. The structural parameters, frontier orbitals and relative stabilities of these systems are also reported. The DFT scheme exaggerates the magnitude as well as the chain length dependence of β
vec with respect to the HF results. Both B3LYP and B3PW91 functionals give very close results. The DFT optimized structures are characterized by larger delocalization, planarity, and polarization of substituents. The best candidates for NLO materials have been identified from the studied series based on the β
vec values. 相似文献
2.
Niu HaiJun Wang Wen Huang YuDong Zhang YunDong Zhang YunJun Bai XuDuo Liu Yuan 《中国科学B辑(英文版)》2007,50(2):230-237
PolySchiff base containing triphenylamine has been synthesized by polycondensation and character-ized by FT-IR,NMR,UV-visible spectrometer. Measurements of the third-order optical nonlinear sus-ceptibility χ(3) by Z-scan technique have shown that the large nonlinearity is dominated by the two-photon absorption in PSB. The sign and size of real part Reχ(3) ,nonlinear refractive index n2 have been measured with the condition of 532 nm,8 ns-duration pulses to be -1.23×10-10 esu,-3.06×10-12 esu;nonlinear absorption index β and size of image part Imχ(3) to be 3.63×10-10 m/W,1.15×10-11 esu,respec-tively,so the third-order nonlinear susceptibility χ(3) is 1.19×10-11 esu. The value is larger than other polymers reported. PSB is self-focusing material and has potential application in nonlinear optic field. 相似文献
3.
Xiu-Xin Sun 《Journal of organometallic chemistry》2011,696(21):3384-3391
The second-order nonlinear optical (NLO) properties have been carried out on a series of Ru(II) complexes with different 4′-substituted terpyridine derivatives and the tridentate ligand 2,6-bis(benzimidazole-2-yl)pyridine by using density functional theory (DFT). The introduction of different substituents enhances the static first hyperpolarizabilities in various degrees. Time-dependent density functional theory (TD-DFT) calculations indicate that the additional metal-to-ligand charge transfer (MLCT) transition, which is vectorially opposite to the intraligand charge transfer (ILCT) transition, could contribute to the smaller βvec in species with electron-withdrawing groups compared to ones with electron-donating groups. The stepwise deprotonation brings about a change in electron density of the benzimidazole moiety and finally makes the moiety turn to be as donor, which subsequently leads to an efficient second-order NLO switching. For the species 3 with electron-donating group, the βvec value of the mono-deprotonated system is 49.9 and 11.1 times as small as that of its diprotonated and fully deprotonated ones. 相似文献
4.
We have studied the ground and excited states of the three dendritic polynuclear Pt(II) complexes 1-[Cl(PH3)2PtC≡≡ C]-3,5-[HC≡≡ C]C6H3 (1), 1,3-[Cl(PH3)2PtC≡≡ C]2-5-[HC≡≡ C]C6H3 (2), and 1,3,5-[Cl(PH3)2- PtC≡≡ C]3C6H3 (3), by using the B3LYP and UB3LYP methods, respectively. TDDFT approach with the PCM model was performed to predict the emission spectra properties of 1―3 in CH2Cl2 solution. We first predicted the excited-state geometries for the three complexes. With the change of the number of Pt(II) atom, 1―3 show the different geometry structures in both the ground and excited states; fur- thermore, the increase of the metal density from 1 to 3 results in the red shift of the lowest-energy emissions along the series. The luminescent properties of 1 are somewhat different from those of 2 and 3. The emission properties of 2 and 3 are richer than 1. Our conclusion can give a good support for designing the high efficient luminescent materials. 相似文献
5.
Interactions between a symmetrical tetramethyl-substituted cucurbit[6]uril (host: TMeQ[6]) and 1,ω-alkylenedipyridine (ω =
2, 4, 6, 8, 10) dicationic guests were investigated using 1H NMR spectroscopy and single crystal X-ray crystallography. In these inclusion complexes, combined cavity and portal binding
in TMeQ[6] were observed, and the length of the bridged alkylene was found to play an important role not only in balancing
the overall hydrophilic/hydrophobic interaction between the host and the guest, but also in defining the structure of the
resulting inclusion complexes. For the guest 1,2-ethylenedipyridine (Edpy), TMeQ[6] includes a positively charged pyridine
ring of Edpy to form an unsymmetrical inclusion complex; for the guest 1,4-butylenedipyridine (Bdpy), TMeQ[6] includes a positively
charged pyridine ring of Bdpy, but the different competitive interactions in and between the related inclusion complexes could
lead to a fast exchange between the hosts and guests. For the guests with longer bridge chains, such as 1,6-hexamethylenedipyridine
(Hdpy) or 1,8-octylenedipyridine (Odpy), a stable pseudorotaxane inclusion complex is formed by combining the hydrophobic
cavity and the outer portal dipole-ion interactions. However, for 1,10-decatylenedipyridine (Ddpy), the two TMeQ[6] host molecules
include the two end pyridine rings of Ddpy and form a dumbbell inclusion complex.
Supported by the National Natural Science Foundation of China (Grant Nos. 20662003 & 20767001), the International Collaborative
Project of Guizhou Province (Grant No. 2007400108), the Science Technology Fund of Guizhou Province (Grant No. J-2008-2012)
and the Natural Science Youth Foundation of Guizhou University (Grant No. 2007-005) 相似文献
6.
To analyze the effect of redox state changes on the second-order nonlinear optical (NLO) responses of organoimido-functionalized Keggin-type heteropolyanions, the excitation properties and static second-order polarizabilities of fully oxidized state, the first and second reduced states were calculated by means of the time-dependent density functional theory (TDDFT) method combined with the sum-over-states (SOS) formalism. The incorporation of extra electrons causes significant enhancement in the second-order NLO activity. The reduced complexes show more than three times the efficiency of fully oxidized state. Moreover, the NLO activities for PW11ReVNPh system can also be modified by controlling the spin multiplicity. The high spin state (3 3) has twice larger β vec value than the low spin state (1 3). The characteristic of the charge-transfer transition corresponding to the dominant contributions to the β vec values indicates that metal-centered redox processes influence the intramolecular donor or acceptor character, which accordingly leads to the variations in the computed β values. Owing to the reversible and manipulable redox processes, these kinds of the POM-based hybrid complexes could comprise a promising family of three-state redox-switchable molecular device combining chromic, magnetic, and NLO output. 相似文献
7.
Small crystal zeolites ZSM-5 with sizes of 150–300 nm were synthesized using the colloidal silicate precursors as the silica
source created by the acid-catalyzed hydrolysis of tetraethylorthosilicate with tetrapropylammonium bromide as the structure-directing
agent within a short crystallization time of 20–35 h. The precursors and final products were detected by XRD, SEM, ICP and
DLS.
Supported by the National Natural Science Foundation of China (Grant No. 20776069), Key Natural Science Foundation for Universities
of Jiangsu Province (Grant No. 06KJA53012), and Program for Changjiang Scholars and Innovative Research Team in University
(Grant No. PCSIRT 0732) 相似文献
8.
Solid complexes [REL(NO3)3]n with novel (10,3)-a type three-dimensional networks structure have been assembled using rare earth nitrates and an amide type semirigid tripodal bridging ligand, 1,3,5-tris {[(2′-benzylaminoformyl)phenoxyl]methyl}benzene (L), as building blocks. The complexes were crys- tallized in the orthorhombic system with chiral space group P212121. The whole structure consists of an infinite array of trigonal RE(III) ions bridged by tridentate ligands, and a novel (10,3)-a net is formed, which is very uncommon in the rare earth complexes. At room temperature, the Sm(III), Eu(III), Tb(III), Dy(III) complexes all exhibited characteristic luminescence emissions of central metal ions under UV light excitation. 相似文献
9.
S. B. Érenburg L. N. Mazalov N. V. Bausk M. K. Drozdova 《Journal of Structural Chemistry》1994,35(4):517-522
SKα, SKβ, ClKβ, ClKβ, and PdLβ2 X-ray fluorescent and PdK EXAFS spectra were obtained for some organic solutions of dialkyl sulfide complexes with palladium
chloride. Solvent effects on the electronic and spatial structure of complexes in solution are discussed. In the benzene solution
of [PdCl22(C6H13)2S], complex molecules interact with solvent molecules along a coordinate that is perpendicular to the plane of the complex
molecule.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 4, pp. 105c111, July–August, 1994.
Translated by L. Smolina 相似文献
10.
Chan Yao Li-Kai Yan Wei Guan Chun-Guang Liu Ping Song Zhong-Min Su 《Journal of Cluster Science》2010,21(2):69-80
The second-order nonlinear optical (NLO) properties of Keggin-type organosilicone derivatives [PW11O39(RSi)2O]3− are investigated by time-dependent density functional theory (TDDFT). Our results indicated that the length of conjugated
chain R has a crucial effect on the charge transfer (CT). The direction of CT alters with the end-cap-substituted electron
donating or accepting moieties (NH2 or NO2), until the chain length reach a certain length, as the CT originates from the heteropolyanion to organosilicone moiety along
the chain, further chain lengthening leaves this behavior invariant. The derivatives with long chain substitution and end-cap-substituted
electron acceptor (NO2) display excellent second-order NLO responses. The system 18 with the relevant long conjugated polyphenylethynyl chain and
end-cap-substituted electron acceptor (NO2) has the largest β
0 value, 4538.1 × 10−30 esu. The present investigation provides important insight into the characteristic of CT and NLO properties of Keggin-type
organosilicone derivatives. 相似文献
11.
XueQin Chang Shun Wang DaJie Lin WeiPeng Guan Huan Zhou ShaoMing Huang 《中国科学B辑(英文版)》2009,52(3):318-324
An indium tin oxide (ITO) electrode modified with monolayer clay/[Ru(phen)2(dC18bpy)]2+ (phen=1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′ bipyridyl) hybrid film has been fabricated by the Langmuir-Blodgett
(LB) method. Atomic force microscopy revealed that the single-layered hybrid film of clay/[Ru(phen)2(dC18bpy)]2+ (denoted as Clay-Ru) was closely packed at a surface pressure of 25 mN·m−1 and had a thickness of 3.4±0.5 nm. Cyclic voltammograms showed that the redox current of Ru(II) complex decreased when incorporated
into the clay film, suggesting that the clay layer acts as a barrier against electron transfer. When applied to oxidizing
the mononucleotide of guanosine 5′-monophosphate (GMP), a large catalytic oxidative current was achieved on the Clay-Ru(II)
modified ITO electrode at the external potential above 900 mV (vs. Ag|AgCl|KCl) and, more significantly, this response was
further enhanced by light irradiation (λ>360 nm), in which the photocurrent is increased about 11 times in comparison with
that of a bare ITO. Mechanism of the photoelectrocatalytic effect was proposed in terms of the reduction of the photoelectrochemically
generated Ru(III) complex in the Clay-Ru film by GMP.
Supported by the National Natural Science Foundation of China (Grant Nos. 20471043 and 20843007), Zhejiang Provincial Natural
Science Foundation (Grant Nos. Y404118 and Y408177), the “151” Distinguished Person Foundation of Zheji-ang Province of China,
Zhejiang Technology Project Foundation (Grant No. 2007C21134) and Wenzhou Technology Project Foundation (Grant No. N2004B040) 相似文献
12.
The magnetic exchange interactions between the dimanganese(II)-substituted complexes and the heteropolymolyanion, [MnII
2(X
n+Mo9O33)2]2(n−10)− (X = PV(I), AsV(II) and SeVI(III)), are investigated by using density functional theory combined with broken-symmetry approach (DFT-BS) method. The calculated
magnetic exchange coupling constant (J) of complex II is in reasonable agreement with the responding experimental value and the negative J values indicate that antiferromagnetic exchange interactions exist in these complexes. Furthermore, the influence of the
central heteroatom on the exchange coupling within the dimanganese core unit is studied from standpoints of geometry, spin
density and frontier orbitals. It demonstrates that the change of the heteroatom X via PV-AsV-SeVI elongates the distances of Mn1...Mn2 and shortens the distances of Ob...Ob, and reduces the effectiveness of the superexchange pathways, consequently, decreasing the magnitude of the antiferromagnetic
coupling constant, J, of these species.
Supported by the National Natural Science Foundation of China (Grant No. 20703008) and Program for Changjiang Scholars and
Innovative Research Team in University (Grant No. IRT0714) 相似文献
13.
Six series of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin Co and Ni complexes (12 kinds) were reported. Nine of the compounds were found to exhibit liquid
crystal properties and display a hexagonal columnar discotic columnar (Colh) phase. Molecular structure of all synthesized compounds was confirmed by IR, UV, MS, 1H NIVR, and elemental analysis. These liquid crystalline compounds have been studied by cyclic voltammetry, luminescence,
and surface photovoltage spectroscopy.
Supported by the National Natural Science Foundation of China (Grant No. 59783001), the Natural Science Foundation of Shandong
Province (Grant No. Y2006B41), the Foundation of Shandong Provincial Education Department (Grant No. J06A53), the Natural
Science Foundation of Shandong University of Technology (Grant No. 2004KJM15) and Doctor Foundation of Shandong University
of Technology 相似文献
14.
An unnatural amino acid, β-[6′-(N, N-dimethyl)amino-2′-naphthoyl]alanine (Ald) showing polarity-sen sitive fluorescence characteristics, was synthesized. A thorough Ald-scan of dynorphin A (Dyn A), the putative endogenous ligand for κ opioid receptors, was then performed. Replacement of the amino acid residues in positions 5, 8, 10, 12 or 14 of Dyn A(1-13)-NH2 with Ald resulted in compounds that had almost equal κ binding affinity compared with that of the parent compound; on the other hand, substi-tution o... 相似文献
15.
Fe3O4 nanorods and Fe2O3 nanowires have been synthesized through a simple thermal oxide reaction of Fe with C2H2O4 solution at 200–600°C for 1 h in the air. The morphology and structure of Fe3O4 nanorods and Fe2O3 nanowires were detected with powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy.
The influence of temperature on the morphology development was experimentally investigated. The results show that the polycrystals
Fe3O4 nanorods with cubic structure and the average diameter of 0.5–0.8 μm grow after reaction at 200–500°C for 1 h in the air.
When the temperature was 600°C, the samples completely became Fe2O3 nanowires with hexagonal structure. It was found that C2H2O4 molecules had a significant effect on the formation of Fe3O4 nanorods. A possible mechanism was also proposed to account for the growth of these Fe3O4 nanorods.
Supported by the Fund of Weinan Teacher’s University (Grant No. 08YKZ008), the National Natural Science Foundation of China
(Grant No. 20573072) and the Doctoral Fund of Ministry of Education of China (Grant No. 20060718010) 相似文献
16.
Three chiral compounds were successfully separated in a short time with two enantiomer separation models on packed-capillary
electrochromatography (CEC). (i) 75 μm I.D. capillaries were packed with 5 μm β-cyclodextrin (βCD) chiral stationary phase
(CSP). Effects of voltage, pH and concentration of organic modifier on electroosmotic flow (EOF) and chiral separations were
investigated systematically. Enantiomers of a neutral compound (benzoin) and a neutral drug (mephenytoin) were separated within
a short time with high efficiency. Efficiency of 32 000 theoretical plates per meter and resolution (R8) of 1.42 were achieved for enantiomers of benzoin using a βCD packed column with 6.2crn packed length. Efficiency of 45 000
theoretical plates per meter andR8 of 3.40 were obtained for enantiomers of mephenytoin. Especially, the enantiomer separation of mephenytion was performed
in just 3.4 min with R8 of 2.60. (ii) 75 μm I.D. capillary was packed with octadecylsilica particles (ODs). Chiral separation of a basic drug, propranolol,
was studied with chiral agent, via addition of the dimethyl-β-cyclodextrin (DM β-CD) directly into the mobile phase on this
column. Baseline separation and efficiency of 81 000 theoretical plates per meter were achieved for propranolol.
Project supported by the Natural Science Foundation of Liaoning Province, China, the National Natural Science Foundation of
China (Grant No.29875030), and the Excellent Young Scientist Award from the National Natural Science Foundation of China.
(Grant No.29725512). 相似文献
17.
Although humans have spent exactly 100 years combating Alzheimer's disease (AD), the molecular mechanisms of AD remain unclear. Owing to the rapid growth of the oldest age groups of the population and the continuous increase of the incidence of AD, it has become one of the crucial problems to modern sciences. It would be impossible to prevent or reverse AD at the root without elucidating its molecular mechanisms. From the point of view of metal-amyloid-β peptide (Aβ) interactions, we review the molecular mechanisms of AD, mainly including Cu2 and Zn2 inducing the aggregation of Aβ, catalysing the production of active oxygen species from Aβ, as well as interacting with the ion-channel-like structures of Aβ. Moreover, the development of therapeutic drugs on the basis of metal-Aβ interactions is also briefly introduced. With the increasingly rapid progress of the molecular mechanisms of AD, we are now entering a new dawn that promises the delivery of revolutionary developments for the control of dementias. 相似文献
18.
In this essay, some discussions and comments about the paper entitled “Can the decay rate of 32P be changed by mechanic motion?” (Ding et al., Science in China Series B: Chemistry (Chinese version), 2008, 38(11):1035–1037)
are given. It was strongly suggested that its experimental methods, data calculations and conclusion should be reconsidered.
After the data were recalculated, the new results supported that the chiral mechanic motion could induce the changes of radioactive
half life.
Supported by the National Natural Science Foundation of China (Grant Nos. 20571085, and 20877099), Fund of the President of
Chinese Academy of Sciences (Grant No. 0521021T04), 2005/2006 USA Li’s Foundation Merit Prize Fund, Fund of Graduate University
of Chinese Academy of Sciences (Grant No. 065101HM03), and Fund of the Key Laboratory of Nuclear Analysis of the Institute
of High Energy Physics of Chinese Academy of Sciences (Grant No. K129) 相似文献
19.
Yuan Ruo Cao ShuRui Chai YaQin Gao FengXian Zhao Qing Tang MingYu Tong ZhongQiang Xie Yi 《中国科学B辑(英文版)》2007,50(5):620-628
Alternate adsorption of positively charged colloid-Au nanoparticles (nano-Au⊕) and negatively charged hemoglobin (Hb) on L-cysteine (L-cys) modified gold electrode resulted in the assembly of {Hb/nano-Au⊕}n layer-by-layer films/L-cys modified gold electrode. The nano-Au⊕ was characterized by transmission electron micrograph (TEM) and microelectrophoresis. The modified electrode interface morphology was characterized by electrochemical impedance spectroscopy (EIS), atomic force mi- croscopy (AFM), cyclic voltammograms (CV) and chronoamperometry. Direct electron transfer between hemoglobin and gold electrodes was studied, and the apparent Michaelis-Menten constant ( km app) of the modified electrode was evaluated to be 0.10 mmol·L?1. Moreover, the higher activity of proteins in the nano-Au⊕ films could be retained compared with the electropolymerization membrane, since the pro- teins in nano-Au⊕ films retained their near-native structure. Direct electron transfer between hemoglo- bin and electrode and electrochemically catalyzed reduction of hydrogen peroxide on a modified elec- trode was studied, and the linear range was from 2.1×10-8 to 1.2 ×10?3 mol·L-1 (r = 0.994) with a detection limit of 1.1×10-8 mol·L-1 H2O2. 相似文献
20.
Multi-walled carbon nanotubes based catalyst plasmon resonance light scattering analysis of tetracycline hydrochloride 总被引:2,自引:2,他引:0
It was found that multi-walled carbon nanotubes (MWNTs) could catalyze the redox reaction between chlorauric acid (HAuCl4) and reductive drugs such as tetracycline hydrochloride (TC), producing gold nanoparticles (Au NPs). By measuring the plasmon resonance light scattering (PRLS) signals of the resulting Au NPs, tetracycline hydrochloride can be detected simply and rapidly with a linear range of 4―26 μmol/L, a correlated coefficient (r ) of 0.9955, and a limit of detection (3σ) of 6.0 nmol/L. This method has been successfully applied to the detection of tetracycline hydrochloride tablets in clinic with the recovery of 101.9% and that of fresh urine samples with the recovery of 98.3%―102.0%. 相似文献