Modification of the luminescence properties of an Europium(III) Tris(β-diketonate) Complex by Inclusion in γ-cyclodextrin and 2,3,6-trimethyl-γ-cyclodextrin

A 1:1 inclusion compound between octakis(2,3,6-tri-O-methyl)-γ-cyclodextrin (TRIMEG) and the chelate complex Eu(NTA)₃·2H₂O (NTA=1-(2-naphthoyl)-3,3,3-trifluoroacetonate) was prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and photoluminescence spectroscopy. The results were compared with those obtained for the corresponding native γ-CD adduct. Excitation and emission spectra were measured, and the lifetimes were determined for the Eu³⁺ first excited state (⁵D₀). The results indicate the presence of only one low-symmetry environment for the Eu³⁺ cations in the inclusion compounds. Encapsulation of the Europium complex in the two CDs increases the quantum efficiency of the ligand-to-metal energy transfer pathway, but the efficiency of the Eu³⁺ sensitization was significantly higher with TRIMEG as the host molecule. This may be related with the observation that the two hosts appear to have different influences on the Eu³⁺ coordination environments for the guest molecule.     

Crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate. π stacking interactions and luminescence of boron difluoride acetyl acetonates

The crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate was determined. The relationship between the structure and luminescent properties is traced in the series of boron difluoride acetyl acetonates (acetyl acetonate, phenylacetyl acetonate, and phenylthioacetyl acetonate). The presence of the π stacking interactions in boron difluoride phenylthioacetyl acetonate crystals leads to increased intensity and bathochromic shift of the fluorescence band.     

Electronic structures of zinc and palladium tetraazaporphyrin derivatives controlled by fused benzo rings

Zinc and palladium tetracyclic aromatic complexes lying structurally between tetraazaporphyrin (TAP) and phthalocyanine (Pc), that is, monobenzo-, adjacently dibenzo-, oppositely dibenzo-, and tribenzo-fused TAPs, have been prepared, and their electronic structures investigated by electronic absorption, magnetic circular dichroism (MCD), fluorescence, phosphorescence, and time-resolved electron paramagnetic resonance (TREPR) spectroscopy, as well as cyclic voltammetry. The last-named indicated that the first oxidation potentials shift to more negative values with increasing number of the fused benzo rings, but also suggested that the first reduction potential apparently has no correlation with the size and symmetry of the pi-conjugated systems. However, this latter behavior is reasonably interpreted by the finding that the effect of the fused benzo rings on destabilization of the LUMO depends on the orbital to which they are fused (i.e., whether it is an egx or egy orbital), since the LUMOs of TAP complexes are degenerate with D4h symmetry. The energy splitting of the LUMOs, that is, DeltaLUMO, was evaluated experimentally for the first time by analyzing the relationship between the first reduction potential and the size and shape of the pi-conjugated system. Electronic absorption and MCD measurements indicate that the lowest excited singlet states are split in the case of the low-symmetry TAP derivatives, although these excited states are degenerate for Pc and TAP with D4h symmetry. These energy splittings DeltaE(SS) correlate well with the DeltaLUMO values. To investigate the electronic structures in the lowest excited triplet state, zero-field splitting (zfs) was analyzed by time-resolved EPR (TREPR) spectroscopy. The energy splitting in the lowest excited triplet state, DeltaE(TT) was quantitatively evaluated from the temperature dependence of the zfs or spin-orbit coupling of the Pd complexes. Consequently, it is demonstrated that DeltaLUMO, DeltaE(SS), and DeltaE(TT) values exhibiting a mutually good relationship can be determined experimentally.     

Europium-sensitized luminescence determination of oxytetracycline in catfish muscle

An europium-sensitized time-resolved luminescence (TRL) method was developed to determine oxytetracycline (OTC) in cultivated catfish muscle. Extraction of OTC from fish muscle was performed with pH 4.0 ethylenediaminetetraacetic acid (EDTA)-McIlvaine buffer and clean up with hydrophilic-lipophilic balanced copolymer solid phase extraction (SPE) cartridges. The eluate was used without further concentration for TRL measurement in pH 9.0 micellar tris(hydroxylmethyl)aminomethane (TRIS) buffer. Cetyltrimethylammonium chloride (CTACl) was used as surfactant and EDTA as a co-ligand. The excitation and emission wavelengths were set at 388 and 615 nm, respectively. The linear dynamic range was 0-1000 ng g⁻¹ (R²=0.9995). The recovery was 92-112% in the fortification range of 50-200 ng g⁻¹ and the limits of detection (LOD) ranged from 3 to 7 ng g⁻¹. Incurred catfish samples were used to demonstrate the performance of the method around 100 ng g⁻¹, the European Union maximum residue level.     

2-芳基吲哚的敏化光氧化偶合反应

本文研究了十七种2-芳基吲哚(1a-1q)在甲醇-乙酸介质中的亚甲基蓝(MB)敏化光氧化反应, 发现有十五种吲哚(1a-1o)以85%-95%的产率给出2,2'-二芳基-[2,3'-联-1H-吲哚]-3(2H)-酮(2a-2o), 而2-(4-硝基苯基]吲哚(1p)和2-联苯基吲哚(1q)则分别生成2-甲氧基-2-(4-硝基苯基)-1,2-二氢-3H-吲哚-3-酮(7p)和2-联苯基-4H-3,1-苯并恶嗪-4-酮(11q), 其中7p在分离过程中失去甲醇分子给出2-(4-硝基苯基)-3H-吲哚-3-酮(10p)。     

Dissociation of photochromic spiroanthrooxazine dimers in the excited state

The influence of temperature and concentration on the spectral polarization properties of the luminescence and absorption of molecules of the original form of photochromic spiroanthrooxazine (SAO) in petroleum ether and polyethylene was investigated. It was shown that the long-wave part of the absorption spectra of the molecules is formed by at least two -*-type electronic transitions, the oscillators of which are mutually orthogonal. It is suggested that the SAO molecules form dimers in nonpolar media through dipole-dipole interaction, and at high concentrations they also form higher associates. Dimers stable in the ground state dissociate when excited to the second electronic transition with a rate constant of 10¹²–10¹³ s^–1.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Department of the Institute of Solid-State Physics and Semiconductors, Academy of Sciences of Belarus, 211177 Vitebsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 99–106, January, 1992.     

阴离子导向组装：两个具有不同阳离子的多维Ag(I)配合物的晶体结构

Assembly of [Ag（CN）2]^- units with M（Ⅱ）-diamine complex cations [Cu（LN-N）2]^2＋, where LN-N represents L2-diaminopropane （pn） and ethylenediamine （en）, afforded two complexes, [Cu（pn）2][Ag2（CN）4] （1） and [Cu（en）2][Ag3（CN）5] （2）, which were characterized by elemental analysis, IR, UV-Vis and ESR spectra. Single crystal X-ray analyses show that these complexes have 2D and 3D architectures through silver-silver interactions and other weak interactions. The luminescence behaviors of the two complexes were also studied by means of emission spectra.     

Photochromism of 1′,3′,3′-trimethyl-6-piperidinospiro [indoline-2′,3-3H-naphth [2,1-b][1,4]-oxazine]

The effect of the piperidine substituent on the spectral and photochromic properties of spiro(indoline-naphthoxazines) (SINO) in different solvents is studied. The introduction of this substituent into the naphthoxazine fragment of SINO results in the appearance of fluorescence of the initial formA of SINO at low temperatures. This fluorescence gradually disappears as the temperature increases. The temperature and concentration dependences of the spectral parameters of photoinduced formB of SINO make it possible to assume thatB molecules aggregate in non-polar solvents. In all solvents studied, form B, unlike the photoinduced form of the non-substituted spiro naphthoxazine, is stabilized as a bipolar ion with a positive charge on the nitrogen atom of the piperidine substituent. The increase in the rate of thermal decolorization as the medium polarity increases is explained.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 684–688, April, 1995.The authors are grateful to the Belarus' Foundation for Basic Research for financial support of this work.     

A Promising MgII‐Ion‐Selective Luminescent Probe: Structures and Properties of Dy–Mn Polymers with High Symmetry

Two Dy–Mn polymers, {[Dy(L¹)₃Mn_1.5(H₂O)₃]?3.125 H₂O}_n ( 1 , L¹=pyridine‐2,6‐dicarboxylic acid) and {[Dy(L²)₃Mn_1.5(H₂O)₆]?8.25 H₂O}_n ( 2 , L² = 4‐hydroxylpyridine‐2,6‐dicarboxylic acid), with high symmetry (S₆) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 Å diameter, while 2 has a honeycomb‐type 2D structure with the cavity of approximately 14.4 Å diameter. In the construction of multidimensional porous polymers with 3d–4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg²⁺, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg²⁺ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d–4f metal‐based nanoporous polymer to exhibit luminescent selectivity for Mg²⁺. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2 . Thermal gravimetric analyses and powder X‐ray diffraction investigations have also been performed, suggestive of high thermal stability of 1 .     

A bifunctional platinum(II) complex capable of intercalation and hydrogen-bonding interactions with DNA: binding studies and cytotoxicity

The interactions of [Pt(CNN)(4-dpt)]PF(6), (1; 4-dpt=2,4-diamino-6-(4-pyridyl)-1,3,5-triazine, HCNN=6-phenyl-2,2'-bipyridine) with double-stranded DNA, poly(dA-dT)(2), and poly(dG-dC)(2) were examined by spectroscopic, electrophoretic, and hydrodynamic methods. The spectroscopic data were analyzed with McGhee, van't Hoff, and Gibbs-Helmholtz equations. In a comparative study, [Pt(CNN)(py)]PF(6) (2; py=pyridine) was prepared and the nature of its binding towards DNA was investigated [preliminary results: ChemBioChem 2003, 4, 62-68]. For reactions with calf thymus DNA at 20 degrees C, the intrinsic binding constants for 1 and 2 are (4.6+/-0.2)x10(5) and (2.3+/-0.3)x10(4) mol(-1) dm(3), respectively. Results of DNA-binding reactions revealed that 1 and 2 preferentially bind to the AT sequence of duplex DNA. Intercalation is the preferred binding mode for 2, whereas both intercalation and minor-groove binding are observed for 1. Complex 1 is cytotoxic against a number of carcinoma cell lines, including KB-3-1, CNE-3, and HepG2, and remains potent against multidrug- or cisplatin-resistant KB-V-1 and CNE1 cell lines, for which the resistance ratios are 1.6 and 1.5, respectively. Importantly, 1 is almost an order of magnitude less toxic to the normal cell line CCD-19Lu (IC(50)=176+/-1.7 microM) and it selectively induced apoptosis leading to cancer cell death with less than 5 % detectable necrosis.