161724-80-7Relevant academic research and scientific papers
Synthesis and infrared and fluorescence spectral properties of luminescent terbium and europium complexes with open-chain carboxylate crown ethers.
Qin, Wenwu,Zhang, Yanling,Liu, Weisheng,Tan, Minyu
, p. 3085 - 3092 (2003)
Two open-chain carboxylate crown ether ligands and their terbium(III) and europium(III) complexes were synthesized and characterized. The terbium and europium ions were found to coordinate to the carboxylate oxygens. The fluorescence properties of europium complexes in the solid state and terbium complexes in the solid state and in the organic solvent were studied in detail, respectively. Under the excitation of ultraviolet light, strong green fluorescence of solid terbium complexes and red fluorescence of solid europium complexes were observed. These observations show that the two ligands favor energy transfer to the emitting energy level of Tb(3+). Some factors that influencing the fluorescent intensity were also discussed.
Efficient synthesis of macrocyclic dilactam crown ethers by fast addition method
Rahimizadeh,Eshghi,Rostami,Faghihi
, p. 73 - 81 (2007/10/03)
A simple and convenient method for preparing macrocyclic dilactam crown ethers containing N2O5, N3O3, N 3O4, N3O5 and N2O 10 donor atoms with 18-32 membered
Crown Ethers as New Catalysts in the Highly Regioselective Halogenative Cleavage of Epoxides with Elemental Halogen
Sharghi, Hashem,Massah, Ahmad Reza,Eshghi, Hossein,Niknam, Khodabakhsh
, p. 1455 - 1461 (2007/10/03)
The regioselective ring opening halogenation of some epoxides using elemental iodine and bromine in the presence of a series of new synthetic macrocycle diamides and also dibenzo-18-crown -6, 18-crown-6, and aza-18-crown-6 has been studied. The epoxides were subject to cleavage by elemental halogen (I2 and Br2) in the presence of these catalysts under mild reaction conditions in various aprotic solvents. In this study, reagents and conditions have been discovered with which the individual halohydrins can be synthesized in high yield and with more than 95% regioselectivity. The results can be discussed in terms of a four-step mechanism: (1) formation of a charge-transfer complex between catalyst and halogen, (2) release of halogen nucleophile from the complex, (3) reaction of the active nucleophile at the less sterically-hindered site in the epoxide, and (4) regeneration of catalyst. The major advantages of this method are high regioselectivity, simple regeneration of catalyst and its reuse through several cycles without a decrease in activity, and ease of workup of the reaction.
New fluorimetric alkali and alkaline earth metal cation sensors based on noncyclic crown ethers by means of intramolecular excimer formation of pyrene
Suzuki, Yoshio,Morozumi, Tatsuya,Nakamura, Hiroshi,Shimomura, Masatsugu,Hayashita, Takashi,Bartsh, Richard A.
, p. 7910 - 7917 (2007/10/03)
New fluorescent reagents, 2,2′-[oxybis(3-oxapentamethyleneoxy)]-bis[N-(1-pyrenylmethyl)benzamide)] (4) and its analogues (2, 3, and 5) which have two pyrenes at the both terminals of polyoxyethylene compounds, were synthesized, and their complexation behavior with alkaline earth cations was investigated by fluorescence spectrometry, fluorescence lifetimes, and 1H NMR spectrometry. These reagents (3-5) showed strong intramolecular excimer emissions around at 480 nm in the fluorescence spectra. On the complexation with alkaline earth metal cations, the increase of monomer emission around at 400 nm accompanied by the disappearance of intramolecular excimer emission of free reagents was observed. These reagents formed a 1:1 complex, and the order of complex formation constants was Ca2+ ? Sr2+ > Ba2+ > Mg2+ > Li+ for all reagents. 1H NMR spectra of these complexes with alkaline earth cations suggested the helical structures of the complexes. Fluorescence spectral changes at the formation of complexes depended on the chain length of the oxyethylene moiety and metal cations. In all cases, the formation of helical structures at the complexation was supported by the 1H NMR spectra.
Efficient synthesis of macrocyclic diamides
Sharghi, Hashem,Eshghi, Hossein
, p. 913 - 922 (2007/10/02)
Some new macrocyclic dibenzotrioxadiamides, tribenzotrioxadiamides and tetrabenzohexaoxatetraamide (1-9) have been prepared. Compounds (2-9) were obtained in the macrocyclization step by reacting the dicarboxylic acid dichloride (13) with appropriate diam
