共查询到20条相似文献,搜索用时 15 毫秒
1.
R.A. Illos 《Tetrahedron letters》2005,46(48):8427-8430
A three-component molecular system capable of switching fluorescence ON and OFF was designed and synthesized. The new redox-activator optical signal generator is an ‘all-organic’ system composed of 2-chloronaphthoquinone connected to 5-dimethylaminonaphthalene via a non-conjugating piperazine spacer. Both chemo- and electrophotoswitching capabilities were demonstrated. 相似文献
2.
Ana P. Esteves Lígia M. Rodrigues Sanjay Gupta Oldrich Machalicky 《Tetrahedron》2005,61(36):8625-8632
Novel fluorescent N-glycoconjugates containing d-glucose, glycine and coumarin or naphthalenetriazole derivatives were prepared by peptide synthesis type methods. The fluorescence properties (spectra, quantum yields) of the compounds were evaluated. 相似文献
3.
Quinolizinium salts are effective fluorescent reagents for the detection of amines. A series of carbamylquinolizinium salts was synthesized to take advantage of the influence of the carbamyl group on the fluorescence of the heterocyclic aromatic system. The native fluorescence of carbamylquinolizinium derivatives is described. The polycyclic compounds exhibit intense fluorescence which can be measured for 10?10?10?11 M solutions. With the diphenyl derivatives, it is not possible to establish correlations between the Hammett parameters from different substituents and the fluorescence emission. The fluorescence of reaction products with piperidine is described; the emission intensity observed is highest for the polycyclic quinolizinium derivatives, which can be considered as the most appropriate for the detection of amines. 相似文献
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5.
Miomandre F Meallet-Renault R Vachon JJ Pansu RB Audebert P 《Chemical communications (Cambridge, England)》2008,(16):1913-1915
The first-time coupling of fluorescence microscopy with a three-electrode electrochemical cell is described and applied to the investigation of a controlled-potential redox switch of organic fluorophores such as tetrazine derivatives. 相似文献
6.
Panchami Prabhakaran 《Tetrahedron letters》2007,48(10):1725-1727
In this Letter, we describe the unexpected reaction pattern of N,N′N″-tri-Boc-guanidine (TBG) with amines at room temperature and under reflux conditions affording N-substituted guanidines and amidinoureas, potentially important compounds with extensive applications in medicinal chemistry. This investigation shows that TBG is an excellent, readily available common starting material for the synthesis of various N-alkyl guanidines as well as N-alkyl-N′-substituted amidinoureas by simply manipulating the reaction conditions. 相似文献
7.
Hisanori Senboku Kazuo Nakahara Tsuyoshi Fukuhara Shoji Hara 《Tetrahedron letters》2010,51(2):435-2629
Hg cathode-free electrochemical detosylation of N,N-disubstituted p-toluenesulfonamides was successfully carried out by a constant current electrolysis using an undivided cell equipped with a platinum cathode and a magnesium anode in the presence of an arene mediator. The deprotection proceeded efficiently and selectively under neutral and mild conditions with a stoichiometric amount of electricity without the use of an Hg cathode to obtain the corresponding secondary amines in good to excellent yields. 相似文献
8.
Yasunori Yamamoto Kazuo Miyamoto Yasutaka Nakatani Norio Miyaura 《Journal of organometallic chemistry》2006,691(23):4909-4917
Hydroboration of terminal and internal alkenes with N,N′,N″-trimethyl- and N,N′,N″-triethylborazine was carried out at 50 °C in the presence of a rhodium(I) catalyst. Addition of dppb or DPEphos (1 equiv.) to RhH(CO)(PPh3)3 gave the best catalyst for hydroboration of ethylene at 50 °C, resulting in a quantitative yield of B,B′,B″-triethyl-N,N′,N″-trimethylborazine. On the other hand, a complex prepared from (t-Bu)3P (4 equiv.) and [Rh(coe)2Cl]2 gave the best yield for hydroboration of terminal or internal alkenes. 相似文献
9.
Yoshikatsu Ito 《Tetrahedron》2007,63(15):3108-3114
Photocarboxylation of 1,1-diphenylethylene with N,N,N′,N′-tetramethylbenzidine (TMB) in MeCN under bubbling of CO2 proceeded with high catalytic efficiency, giving 3,3-diphenylacrylic acid (DPA) and 3-hydroxy-3,3-diphenylpropionic acid (20). The turnover number (TON=(DPA+20)/TMB) reached 17. Similarly, 1-phenyl-1-cyclohexene yielded cis-2-acetamido-2-phenylcyclohexanecarboxylic acid with TON 5.9. As compared with related N,N-dimethylaniline derivatives, TMB is more resistant to photodecomposition, has the much larger absorbance in the S0→S1 transition, and has the lower quenching efficiency by CO2. Probably these factors are partly responsible for the high TON observed for TMB. 相似文献
10.
A proton-triggered fluorescent switch was developed through direct connection of a proton sponge, 1,8-bis(dimethylamino)naphthalene to a fluorophore, 4-aminonaphthalimide. The molecular fluorescent switch was based on a photoinduced electron transfer (PET) mechanism. The fluorescent switch exhibited significant fluorescence enhancement upon binding the low-concentration protons in high pH aqueous solution. The high pKa value (around 11) of the fluorescent switch could be ascribed to the nature of the proton sponge. 相似文献
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Piotr M?ynarz Agata Rydzewska Ziemowit Pok?adek 《Journal of organometallic chemistry》2011,696(2):457-460
Two groups of new boronic acids containing aminophosphonate functions were synthesized and characterized by NMR spectroscopy and ESI-MS. Both groups of compounds were obtained by simple reactions of prepared in situ tris(trimethylsilyl) phosphite with a corresponding imine. The synthesized compounds may serve as a potential new class of building blocks, BNCT agents and supramolecular host molecules. 相似文献
13.
Lenka Dastychová Marie Sotolářová Dalibor Dastych Jan Taraba Marek Nečas Jiří Příhoda 《Polyhedron》2007
The reaction of P4S10 (1) with N,N′-diphenylurea (PhNH)2CO (2) results in new heterocyclic compounds: the pyridinium salt of 1,3-diphenyl-2-sulfido-2-thioxo-1,3-diaza-2λ5-phosphetidine (3) (with a P–N–C–N cycle) and the pyridinium salt of 1,4-diphenyl-2,5-disulfido-2,5-dithioxo-1,4-dithiadiaza-2λ5,5λ5-diphosphinane (4), containing the (P–S–N)2 cycle and the cyclic thiophosphates [pyH]2[P2S8] (5), [pyH]2[P2S7] (6) and [pyH]3[P3S9] (7). A similar reaction, but carried out with N,N′-diphenylthiourea (PhNH)2CS (8), leads to the formation of 4 and 6. pyPS2Cl (9), used as an alternative starting material, also yields compounds 3, 4, 5, and further [pyH][PS2Cl2] (10) and S8 after reaction with 2. Compound 3 reacts with Pd(CH3COO)2, with the formation of the complex [Pd(Ph2N2COPS2)2] (11). The crystal structures of 3 and 7 were determined by single-crystal X-ray diffraction. 相似文献
14.
A novel fluorescent molecular switch for the detection of nucleic acid hybridization has been explored in relation to the
development of a structure that would be amenable for operation when immobilized for solid-phase analyses. The structure was
prepared by self-assembly, and used Neutravidin as the central multivalent docking molecule, a newly synthesized biotinylated
long-chain linker for intercalating dye that was modified with thiazole orange (TO) at one end, and a biotinylated probe oligonucleotide.
Self-assembly of the biotinylated components on adjacent Neutravidin binding sites allowed for physical placement of an oligonucleotide
probe molecule next to tethered TO. The TO located at the end of the flexible linker chain was available to intercalate, and
could report if a duplex structure was formed by a probe–target interaction by means of fluorescence intensity. Subsequently,
regeneration of the single-stranded probe was possible without loss of the intercalator to solution. The switch constructs
were assembled in solution and subsequently immobilized onto biotin functionalized optical fibers to complete the sensor design.
Solution-phase fluorescence lifetime data showed a biexponential behavior for switch constructs, suggesting intercalation
as well as a significant secondary binding mode for the immobilized TO. It was found that the secondary binding mechanism
for the dye to DNA could be decreased, thus shifting the dye to intercalative binding modes, by adjusting the solution conditions
to a pH below the pI of Neutravidin, and by increasing the ionic strength of the buffer. Preliminary work demonstrated that
it was possible to achieve up to a fivefold increase in fluorescence intensity on hybridization to the target. 相似文献
15.
Crystals of the cadmium(II) complexes of N,N-diisopropylthiourea and N,N-dicyclohexylthiourea were obtained and their X-ray single crystal structures determined. These complexes are air-stable, easy to prepare and inexpensive and decompose cleanly to give good quality crystalline CdS. The nanoparticles of CdS thus obtained showed quantum confinement effects in their optical spectra, with close to band-edge emission in luminescence experiments. The broad diffraction patterns observed are typical of nanodimensional particles. The variation of concentration of precursor-to-HDA ratio change the isolated materials from spheres to rod-shaped. TEM images showed agglomerates of needle-like plate of particles. 相似文献
16.
Michael J Sheehy Mashita Yamashita Jennifer White-Colangelo Ron Orlando 《Journal of organometallic chemistry》2004,689(9):1511-1520
The N-ferrocenoyl amino acid ester derivatives FcCOR {Fc=(η5-C5H5)Fe(η5-C5H4)} where R=Gly(OMe) 1, Gly(OEt) 2, Gly(OBn) 3, l-Ala(OMe) 4, l-Ala(OEt) 5, l-Leu(OMe) 6, l-Leu(OEt) 7, l-Leu(OBn) 8, l-Phe(OMe) 9 and l-Phe(OEt) 10, were prepared by coupling ferrocene carboxylic acid with the appropriate amino acid ester starting materials using the 1,3-dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBt) protocol and these have been characterised by spectroscopic techniques. The electrochemical anion sensing behaviour of compounds 1-10 with several anions using a platinum microdisk working electrode is described, together with 1H NMR anion complexation studies. The X-ray single crystal structure of N-ferrocenoyl-l-alanine methyl ester 4 has been determined and contains two molecules which differ slightly in conformation in the asymmetric unit of space group P21 (No. 4); principal dimensions are amide N(H)CO 1.224(6) and 1.231(6) Å, ester CO 1.220(10) and 1.190(7) Å, with N-H?OC(amide) as the primary intermolecular hydrogen bond, N?O 2.992(6) and 2.971(6) Å and with graph set C(4). 相似文献
17.
Aromatic ureas bearing N-(2-alkylaryl) groups may be laterally lithiated by treatment with sec-butyllithium. Quenching with a range of electrophiles yields functionalised aryl ureas in excellent yield. Lateral lithiation is favoured when the urea nitrogen adjacent to the aromatic ring in question is alkylated, and when competitive lithiations of such a ring are possible, lateral lithiation is more favourable than the alternative ortholithiation. 相似文献
18.
Laxhmaiah Alakonda 《Journal of organometallic chemistry》2009,694(24):3859-660
Chiral N,N′-diaryl C2-symmetric diamines and N-aryl,N′-formyl-trans-(1R,2R)-diaminocyclohexane are readily accessed by copper catalyzed N,N′-diarylation and N-aryl,N′-formylation of trans-(1R,2R)-diaminocyclohexane with aryl bromides. N,N′-diarylation using (R)-1,1′-binaphthyl-2,2′-diamine and iodobenzene gave the corresponding (R)-N,N′-diphenyl-1,1′-binaphthyl-2,2′-diamine derivative in 83% yield. 相似文献
19.
Maria Daoudi Abdelali Kerbal Jean-Pierre Launay Taibi Ben Hadda Pierre H. Dixneuf 《Tetrahedron》2006,62(13):3123-3127
A series of tridentate ligands N,N-bis-[(di-substituted-1-pyrazolyl)methyl]arylamines 2-3a,b and benzylamine 4a,b, tetradentate N,N′-bis-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 7a,b and hexadentate N,N,N′,N′-tetra-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 8a,b has been prepared in good yield by condensation of arylamines, benzylamine or para-phenylenediamine with N-hydroxymethyl disubstituted pyrazoles 1a,b. The synthesis and characterisation of these various polydentate ligands are described. 相似文献
20.
Issa Yavari Nargess Hosseini Loghman Moradi Anvar Mirzaei 《Tetrahedron letters》2008,49(27):4239-4241
A mild, convenient, and practical one-pot procedure for direct synthesis of N,N′-dialkyl-N″-dialkylaminocarbothioyl thioureas is described via three-component reaction of cyclic secondary amines, CS2, and N,N′-dialkyl carbodiimides in water at room temperature. 相似文献