Abstract: NIR dyes have become popular for many applications, including biosensing and imaging. For this reason, the mol. switch mechanism of the xanthene dyes makes them useful for in vivo detection and imaging of bioanalytes. Our group has been designing NIR xanthene-based dyes by the donor-acceptor-donor approach; however, the equilibrium between their opened and closed forms varies depending on the donors and spacer. We synthesized donor-acceptor-donor NIR xanthene-based dyes with an alkyne spacer via the Sonogashira coupling reaction to investigate the effects of the alkyne spacer and the donors on the maximum absorption wavelength and the mol. switching (ring opening) process of the dyes. We evaluated the strength and nature of the donors and the presence and absence of the alkyne spacer on the properties of the dyes. It was shown that the alkyne spacer extended the conjugation of the dyes, leading to absorption wavelengths of longer values compared with the dyes without the alkyne group. In addition, strong charge transfer donors shifted the absorption wavelength towards the NIR region, while donors with strong π-donation resulted in xanthene dyes with a smaller equilibrium constant DFT/TDDFT calculations corroborated the exptl. data in most of the cases. Dye 2 containing the N,N-dimethylaniline group gave contrary results and is being further investigated.
Abstract: Commercially available and inexpensive potassium bis(trimethylsilyl)amide (KHMDS) serves as an efficient transition metal-free catalyst for the catalytic sp C?H silylation of several terminal alkynes including two pharmaceuticals. Overall, the presented system allows the synthesis of various attractive silylacetylenes under mild conditions, making this approach an environmentally benign and sustainable alternative to existing synthetic solutions.
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With bis-triphenylphosphine-palladium(II) chloride; copper(l) iodide; triethylamine; In toluene; at 20℃; for 18h;
According to general procedure N2, cmpd 3 (284.8 mg, 0.417 mmol), pmethoxyphenylacetylene(48.4 mg, 0.366 mmol, 0.88 equiv), [PdCl2(PPh3)2](8.7 mg, 3.0 mol%) and CuI (2.1 mg, 2.6 mol%) were stirred in a solution oftoluene (100 mL) and Et3N (10 mL) at rt for 18 h. The reaction medium was evaporated to dryness andpurified by column chromatography (SiO2, using a gradient of eluent EtOAc/petroleum ether/CH2Cl2(4/95/1 to 0/0/100). The desired mono-coupled product was obtained as a purple solid (111.5 mg, 42%),while the bis-coupled was obtained as a blue solid (40.2 mg, 12%) and a part of starting material (113.7 mg,40%) was recovered. Mono-coupled product
With potassium fluoride; sodium azide; silver carbonate; In N,N-dimethyl-formamide; at 50℃; for 6.0h;
General procedure: to a solution of phenylacetylene (1a)(0.055 mL, 0.5 mmol), 2,6-di-tert-butyl-4-methylphenol(BHT) (2a) (133 mg, 0.6 mmol), NaN3 (39 mg, 0.6 mmol)and KF (58 mg, 1.0 mmol) in DMF (1 mL) at 50 C, Ag2CO3(41 mg, 0.15 mmol) was added. The reaction mixture wasthen stirred for 6 h when TLC conformed that substrate 1a was consumed. The resulting reaction mixture was cooled toroom temperature and extracted by dichloromethane(3×15 mL). The organic layer was washed with brine(3×40 mL), dried over MgSO4 and concentrated. Purificationof the crude product via flash column chromatography (silicagel; petroleum ether) and concentratinon in vacuo affordedthe desired product of 3a-N2/3a-N1 in 91% yield.
With copper(l) iodide; tetrakis(triphenylphosphine) palladium(0); triethylamine; In tetrahydrofuran; at 70℃; under 7.50075e-05 Torr; for 10h;Inert atmosphere;
In this embodiment, a white light emitting material is synthesized, and the chemical structure formula of the white light emitting material is as follows:The preparation method includes the following steps:(1) 5.0 mmol of tris (4-iodophenyl) amine, 21.0 mmol of 4-methoxyphenylacetylene, 30.0 mL of tetrahydrofuran,7.0mL of triethylamine was placed in a 100mL double-necked flask equipped with a stir bar and connected to a reflux tube;(2) The above reaction mixture is evacuated with a vacuum pump so that the pressure reaches 1x10-2Pa, and then nitrogen is passed in,Repeat the evacuation and nitrogen flow three times to maintain the nitrogen atmosphere of the reaction system;(3) adding 0.125 mmol of tetra (triphenylphosphine) palladium and 0.8 mmol of cuprous iodide to the above reaction solution under a nitrogen environment;(4) The above reaction mixture was heated to 70 C. under the protection of nitrogen and kept at reflux for 10 hours.The solvent was then evaporated to dryness on a rotary evaporator and washed with a small amount of ethyl acetate to give a yellow powder.Purified by column chromatography (silica gel column model: Yantai Jiangyou F-254 200-300 mesh,The mobile phase is a mixed solvent of methylene chloride and n-hexane, and the volume ratio of methylene chloride to n-hexane is 1:30).A white solid powder was obtained, that is, the white light-emitting material.The obtained white solid powder was characterized by carbon spectrum and proton spectrum.
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