共查询到20条相似文献,搜索用时 31 毫秒
1.
《Journal of Molecular Structure》2000,526(1-3):165-175
Crystallographic studies of (2:1) salts of picric acid with 1,5-diamino-3-oxapentane (1OPICR), 1,8-diamino-3,6-dioxaoctane (2OPICR) and 1,5-diamino-3-azapentane (1NPICR) showed significant conformational change of the picrate ion due to numerous electrostatic, H-bonding and π–π stacking interactions present in the crystal lattice. In particular, intermolecular N–HO H-bonds were found to cause significant twisting of the o-NO2 groups from the plane of the benzene ring, whereas overlapping of the picrate ions due to electrostatic interactions and π–π stacking caused flattening of the molecule. Analysis of the geometry of 74 picrate ions found in the Cambridge Crystallographic Database, in their various crystallochemical environments, showed that competition between essentially weak but numerous intermolecular interactions of different types led to systematic changes in geometric parameters within the picrate ion. In particular, relations found between the C1–C2–N–O (C1–C6–N–O) torsion angle and the endocyclic C1–C2–C3 (C1–C6–C5) valence angle can be explained on the basis of competition between resonance effects of the o-NO2 group and π–π stacking. 相似文献
2.
Yao Dong Huang Hai Tao Yu Ji Ben Meng Teruo Matsuura Yong Mei Wang 《Journal of Molecular Structure》2002,610(1-3):247-252
The title compound, 9,10-dihydro-9,10-etheno-1,8-dichloro-11-diphenylphosphinyl-12-(diphenylphosphinylethynyl)anthracene (1), has been synthesized and its crystal structure has been determined. The compound 1 crystallized into the triclinic space group P-1 with
=74.837(4)°, β=88.156(4)°, γ=65.398(4)°,
Z=2, Dc=1.352 gcm−3. In the crystal structure of 1a, one chloroform molecule was included by the compound 1 with a 1:1 ratio and the existence of non-classical intermolecular C–HO hydrogen bonds, intramolecular C–HCl and C–HO hydrogen bonds and π–π stacking were observed. 相似文献
3.
Zeev Goldschmidt Elisheva Genizi Hugo E. Gottlieb Dafna Hezroni-Langermann
Heinz Berke
H. William BoschJosef Takats
《Journal of organometallic chemistry》1991,420(3):419-429(η4-Cycloheptatriene)Ru(CO)3 reacts with tetracyanoethylene (TCNE), 4-phenyltriazoline-3,5-dione (PTAD) and (carbomethoxy)maleic anhydride (CMA) to give stable 3 + 2 σ,π-allylic adducts. The 3 + 2 adduct with TCNE equilibrates via a [4,4]-sigmahaptotropic rearrangement with the less stable 6 + 2 adduct, which decomposes under the reaction conditions to the demetallated 6 + 2 adduct. It is concluded that σ,π-allylic adducts are in general more stable than their isomeric η4-π counterparts. The structure of the 3 + 2 TCNE adduct was determined by a single-crystal X-ray diffraction study. 相似文献
4.
Yu-Jun Shi Shu-Jian Chen Bin Huang Xue-Tai Chen Yong Zhang Xiao-Zeng You 《Journal of Molecular Structure》2003,650(1-3):27-32
The mixed ligand mononuclear copper(I) complex of formula [CuI(PPh3)(DPPZ)]·DMF (DPPZ=dipyrido[3,2,-a:2′,3′-c]phenazine) has been synthesized and has been characterized by single-crystal X-ray diffraction method, FT-IR spectrum, the electrospray ionization mass spectrum and the thermogravimetric analysis. The pairwise π–π stacking between DPPZ ligands exists through the crystal lattice. 相似文献
5.
6.
Hai-Ying Bie Jie-Hui Yu Ji-Qing Xu Jing Lu Yong Li Xiao-Bing Cui Xiao Zhang Ying-Hua Sun Ling-Yun Pan 《Journal of Molecular Structure》2003,660(1-3):107-112
A novel copper(II) thiocyanate complex [Cu(im)2(NCS)2] 1 (im=imidazole) has been prepared and characterized by spectroscopic analysis and crystallographic method. This supramolecular compound exhibits a three-dimensional solid state structure constituted by N–HS hydrogen bonds and π–π stacking interactions. The compound in DMF solutions has a very strong third-order non-linear optical (NLO) behavior with absorption coefficient and refractive index 2=1.18×10−11 mw−1, n2=−9.00×10−16 m2w−1, respectively, and third-order NLO susceptibility χ(3) of 7.00×10−10 esu. 相似文献
7.
Xiao-Juan Liu Ji-Kang Feng Ai-Min Ren Xin Zhou 《Journal of Molecular Structure》2003,620(2-3):177-188
The two-photon absorption (TPA) cross-sections of a series of bifluorene molecules with different substituents (constructing three types of structures D–π–D, A–π–A and D–π–A) were calculated using ZINDO/SOS program. The results showed that the A–π–A structure with strong substituent-nitro had the largest TPA cross-section for these molecules. To verify the results, we analyzed the charge quantity of the ground and the main excited states as well as the frontier orbitals of the investigated molecules. The equilibrium geometries were obtained with AM1 method, and using ZINDO-SOS to calculate the third-order nonlinearities of the molecules, then gained the TPA cross-sections. We found that for the compounds with bifluorene as π center, the donor and acceptor strength are the important factor for the enhancement of the TPA properties, and compared with molecules with fluorene as π center, the large TPA cross-sections of bifluorene are caused by coupling effects between the two monomers. 相似文献
8.
Two Schiff bases N,N′-(bis(pyridin-2-yl)benzylidene)propane-1,3-diamine (pbpd) and N,N′-(bis(pyridin-2-yl)formylidene)butane-1,4-diamine (pfbd) have been prepared and used to synthesize copper(II) complexes. Four complexes of the type [Cu(L)(N3)]X (1–4) [L = pbpd; X = ClO4 (1); L = pbpd; X = PF6 (2); L = pfbd; X = ClO4 (3); L = pfbd; X = PF6 (4)] have been synthesized and characterized on the basis of microanalytical, spectroscopic, magnetic, electrochemical, luminescence and other physicochemical properties. Two representative complexes of the series, 2 and 3, have been characterized by single crystal X-ray diffraction measurements which reveal that in each complex the copper(II) ion assumes a distorted trigonal bipyramidal environment through coordination of the metal centre by two pyridine N atoms and two imine N atoms of the Schiff base with the fifth position occupied by a N atom of a terminal . They display intraligand 1(π–π*) fluorescence at room temperature and intraligand 3(π–π*) phosphorescence in glassy solutions (MeOH at 77 K). A band (492 nm) observed for the complexes in their solid-state emission spectra is an excimeric emission arising due to an aromatic π–π interaction. Electrochemical electron transfer study reveals CuII–CuI reduction in methanolic solutions. 相似文献
9.
A new electrochemical sensor for ATP with synthetic cyclophane stably attached onto single-walled carbon nanotubes (SWNTs) as the recognition elements is described. UV-vis and cyclic voltammetric results demonstrate that ATP may interact with the synthetic cyclophane recognition elements to form a stable adduct mainly through electrostatic, π-π stacking and donor-acceptor interactions. Such interactions eventually lead to a decrease in the peak currents of the cyclophane recognition elements attached onto t... 相似文献
10.
A. A. Pud S. P. Rogalsky G. S. Shapoval A. P. Kharitonov A. Kemperman 《Polymer Degradation and Stability》2000,70(3):409-415
Fluorination of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) leads to narrowing of its window of electrochemical stability in a cathodic range of potentials. It is found this is connected with appearance of both perfluorinated and incompletely fluorinated units in the polymer. The former units are liable to electrochemical reduction (at potentials <−2.0 V) followed by elimination of fluorine anions and the latter react with basic products (generated at potentials <−1.8 V) of electrochemical reduction of the background solution. In the both cases this results in appearance of conjugated multiple bonds in the fluorinated macromolecules. Quantities of these units in fluorinated PPO were determined with a help of direct and indirect electrochemical reductive degradation techniques. 相似文献
11.
Ya-Pan Wu Cui-Juan Wang Yao-Yu Wang Ping Liu Wei-Ping Wu Qi-Zhen Shi Shie-Ming Peng 《Polyhedron》2006,25(18):3533-3542
Three new complexes {[Cu(dpdapt)(Hhbd)] · 6H2O}n (1) (dpdapt = N,N′-di(2-pyridyl)-2,4-diamino-6-phenyl-1,3,5-triazine, Hhbd = 2-hydroxybutanedioicate dianion), [Cu(dpdapt)(SO4)] · 2H2O (2) and [Cu(dpdapt)(oxa)] · H2O (3) (oxa = oxalate dianion) have been synthesized and structurally characterized. The non-covalent interactions of π–π stacking and hydrogen bonding extend complexes 1–3 into supramolecular architectures, where 1 self-assembles into a 1D polymeric chain by dicarboxylate bridges and exhibits a 3D framework with 1D open channels, while complexes 2 and 3 display 2D wavelike networks. Interestingly, in 1, the host framework encapsulates hexameric water clusters that are connected into 1D arrays by supramolecular association along the 1D open channels. The UV/vis, IR spectra, fluorescence and TG analysis for complexes 1, 2 and 3 are also discussed. 相似文献
12.
1-Phenyl-4-vinylpyrazole reacts with methyl propiolate and N-phenylmaleimide giving via the Diels-Alder 1:1 adducts, products (4) and (8), and also the 1:2 adducts (5), (6) and (9) resulting from an “ene” reaction of the initially forced cycloadducts. The obtention of the adducts (5) and (6) in equimolecular amounts is a good example of the non-regioselective character of the “ene” reaction. The reaction with tetracyanoethylene takes place through the olefinic substituent giving the π2 + π2 adduct (10). 相似文献
13.
Zhengang Guo Xiaoju Li Shuiying Gao Yafeng Li Rong Cao 《Journal of Molecular Structure》2007,846(1-3):123-127
A photoluminescent supramolecular compound [Cd(Hbic)2(H2O)]·(4,4′-bpy)·H2O, H2bic = 1-H-benzimidazole-5-carboxylic acid, has been synthesized and structurally characterized. With CH–π stacking and hydrogen bond, the 4,4′-bipyridine is used as template to construct the neighboring layers into a three-dimensional supramolecular architecture. Solid-state emission spectrum of compound 1 shows luminescence with emission peak at 565 nm. 相似文献
14.
Kitamura Y Kawata K Tanaka K Furuyashiki Y Mifune M Tsukamoto I Saito M Haginaka J Saito Y 《Talanta》2006,69(5):1260-1264
The effect of bromination of Cu-porphyrin-derivative-immobilized silica gels (Cu-TCPPD) was examined by comparing the retention behaviors of polyaromatic hydrocarbons (PAHs) on Cu-TCPPD and Cu-octabromotetrakis(4-carboxyphenyl)porphine-derivative-immobilized silica gels (Cu-OBTCPPD) columns. It was revealed that bromination affects strongly the π–π electron interactions caused from hydration energy in a polar eluent (80% methanol) possibly as a result of a destruction of planar structure of porphine-ring by bromination. It was also revealed that bromination enhances π–d interactions as well as the π–π electron interactions in a broad sense (e.g., dispersion forces) in a non-polar eluent (n-hexane). However, the bromination did not exert much influence on electrostatic interactions caused from polarization of mono-halogenated benzenes. 相似文献
15.
We have systematically investigated the structural features, electronic properties, thermally-induced structural phase transitions and absorption spectra depending on the solvent for ten Cu(II) complexes with 3,5-halogen-substituted Schiff base ligands. Structural characterization of two new complexes, bis(N-R-1-phenylethyl- and N-R,S-2-butyl-5-bromosalicydenaminato-κ2N,O)copper(II), reveals that they afford a compressed tetrahedral trans-[CuN2O2] coordination geometry with trans-N–Cu–N = 159.4(2)° and trans-O–Cu–O = 151.7(3)° for the 1-phenylethyl complex and trans-N–Cu–N = 157.9(3)° and trans-O–Cu–O = 151.0(3)° for the 2-butyl one. All the complexes exhibit a structural phase transition by heating in the solid state regardless of their structures at room temperature. The absorption spectra of a series of ten complexes exhibit a slight shift of the d–d band at 16 000–20 000 cm−1 and remarkable shift of the π–π* band at 24 000–28 000 cm−1, which suggests that the dipole moment of the solvents presumably affects the conformation of the π-conjugated moieties of the ligands rather than the coordination environment. We have also attempted ‘photochromic solute-induced solvatochromism’ by a system of bis(N-R-1-phenylethyl-3,5-dichlorosalicydenaminato-κ2N,O)copper(II) and photochromic 4-hydroxyazobenzene in chloroform solution. We successfully observed a change of the d–d and π–π* bands of the complex in the absorption spectra caused by cis–trans photoisomerization of 4-hydroxyazobenzene. 相似文献
16.
Xiaoming Ren Jingli Xie Youcun Chen Reinhard Karl Kremer 《Journal of Molecular Structure》2003,660(1-3):139-146
The two ion-pair complexes, [pyH]2[Zn(mnt)2] (1) and [4,4′-bipyH2]-[Zn(mnt)2] (2), were synthesized, where mnt2− denotes maleonitriledithiolate, and [pyH]+, [4,4′-bipyH2]2+ represent pyridinium and diprotonated 4,4′-bipyridinium, respectively. Their single crystal structures show that there are strong bifurcated H-bonding interactions between the cations of the pyridinium derivative and the [Zn(mnt)2]2− anions in both 1 and 2. The bifurcated H-bonding interactions between the N–H of the pyridiniums and the CN groups of the mnt2− ligands give rise to a 2D layered H-bonding network, the adjacent layers come together in such way as mutual embrace to give a tight pack, thus 2D hydrogen-bonding sheets further develop into 3D H-bonding networks through weak C–HS and ππ stacking interactions in 1. As for 2, the cations and anions connect into several types of H-bonding macrorings ([2+2], [3+3] and [4+4]), these H-bonding macrorings fuse to extend into 2D layered structure, the interpenetration between [3+3] and [4+4] type H-bonding macrorings in the adjacent layers give further rise to novel 3D extended H-bonding networks, in which there are clearly parallel stacks of cations and the chelate rings of anions. 相似文献
17.
Fan Shi Yijing Ai Baoli Wang Yucen Yao Zejun Zhang Juan Zhou Xianghui Wang Wei Sun 《Molecules (Basel, Switzerland)》2022,27(19)
To build a portable and sensitive method for monitoring the concentration of the flavonoid rutin, a new electrochemical sensing procedure was established. By using nitrogen-doped carbonized polymer dots (N-CPDs) anchoring few-layer black phosphorene (N-CPDs@FLBP) 0D-2D heterostructure and gold nanoparticles (AuNPs) as the modifiers, a carbon ionic liquid electrode and a screen-printed electrode (SPE) were used as the substrate electrodes to construct a conventional electrochemical sensor and a portable wireless intelligent electrochemical sensor, respectively. The electrochemical behavior of rutin on the fabricated electrochemical sensors was explored in detail, with the analytical performances investigated. Due to the electroactive groups of rutin, and the specific π-π stacking and cation–π interaction between the nanocomposite with rutin, the electrochemical responses of rutin were greatly enhanced on the AuNPs/N-CPDs@FLBP-modified electrodes. Under the optimal conditions, ultra-sensitive detection of rutin could be realized on AuNPs/N-CPDs@FLBP/SPE with the detection range of 1.0 nmol L−1 to 220.0 μmol L−1 and the detection limit of 0.33 nmol L−1 (S/N = 3). Finally, two kinds of sensors were applied to test the real samples with satisfactory results. 相似文献
18.
The molecular structures of n-hexane were determined by RHF/4-21G ab initio geometry optimization at 30° grid points in its three-dimensional τ1(C11–C8–C5–C1), τ2(C14–C11–C8–C5), τ3(C17–C14–C11–C8) conformational space. Of the resulting 12×12×12=1728 grid structures, 468 are symmetrically non-equivalent and were optimized constraining the torsions τ1, τ2, and τ3 to the respective grid points, while all other structural parameters were relaxed without any constraints. From the results, complete parameter surfaces were constructed using natural cubic spline functions, which make it possible to calculate parameter gradients, |P|=[(∂P/∂τi)2+(∂P/∂τj)2]1/2, where P is a C–C bond length or C–C–C angle. The parameter gradients provide an effective measure of the torsional sensitivity of the system and indicate that dynamic activities in one part of the molecule can significantly affect the density of states, and thus the contributions to vibrational entropy, in another part. This opens the possibility of dynamic entropic conformational steering in complex molecules; i.e. the generation of free energy contributions from dynamic effects of one part of a molecule on another. When the conformational trends in the calculated C–C bond lengths and C–C–C angles are compared with average parameters taken from some 900 crystallographic structures containing n-hexyl fragments or longer C–C bond sequences, some correlation between calculated and experimental trends in angles is found, in contrast to the bond lengths for which the two sets of data are in complete disagreement. The results confirm experiences often made in crystallography. That is, effects of temperature, crystal structure and packing, and molecular volume effects are manifested more clearly in bond lengths than bond angles which depend mainly on intramolecular properties. Frequency analyses of the τ1, τ2 and τ3 torsional angles in the crystal structures show conformational steering in the sense that, if τ1 is trans peri-planar (170°≤τ1≤180°; −180°≤τ1≤−170°), the values of τ2 and τ3 are clustered closely around the ideal gauche (±60°) and trans (±180°) positions. In contrast, when τ1 is in the region (50°≤τ1≤70°), there is a definite increase in the populations of τ2 and τ3 at −90 and −150°. 相似文献
19.
Liming Wu Yongfan Zhang Jianming Hu Lixin Zhou Junqian Li 《Journal of Molecular Structure》1999,460(1-3):27-35
Using the ab initio method, the vibrational and electronic spectra of binuclear molybdenum clusters which contain Mo2OnS4−n(n=0–4) core were investigated. The main absorption bands in the IR spectra of these clusters are assigned and compared with each other, especially for the case of the trans isomers. The electronic spectra were studied by performing the CIS calculations. The ground state and the first excited state of the clusters were discussed by using the natural bond orbital method. It is shown that the band corresponding to the longest wavelength can be assigned to three kinds of transition types. Two transitions, σ(Mo–Mo)→π*(Mo–Xt)(X=S,O) and σ(Mo–Mo)→σ*(Mo–Mo), can be seen in most cases. 相似文献
20.
Toshiya Okazaki Takeshi Saito Koji Matsuura Satoshi Ohshima Motoo Yumura Yuji Oyama Riichiro Saito Sumio Iijima 《Chemical physics letters》2006,420(4-6):286-290
Band gap photoluminescence (PL) behaviors of single-walled carbon nanotubes (SWNTs) grown by the methods of chemical vapor deposition and pulsed-laser vaporization are investigated over the wide diameter range (≈0.8–1.4 nm). The peak intensity of the PL signals strongly depends on chirality and the ‘(2n + m) family type’ of SWNTs. Based on the PL results, a population analysis of these SWNTs is conducted by combining the calculated PL yields for each (n, m) tube. The results are directly compared with the histograms of diameter distributions estimated by the transmission electron microscope (TEM) observations to check the validity of the analysis. 相似文献